Call for Proposals under the IMOS (EIF) Five Year Strategy: Enhancement / Extension of IMOS July 2009 to June 2013

Transcription

1 Call for Proposals under the IMOS (EIF) Five Year Strategy: Enhancement / Extension of IMOS July 2009 to June 2013 Node Science and Implementation Plan (NSIP) template Proposals should be submitted by 30 October 2009 to: Tim Moltmann, IMOS Director, University of Tasmania tim.moltmann@imos.org.au Background: This template has been provided to allow Node Leaders, and regional representatives of new Nodes to prepare NSIP s following a call for proposals announced on 18 September 2009, with a closing date of 30 October Prior to completing this template, please read the IMOS Five Year Strategy (the Strategy ), and Detailed Guidelines for Proposal Development (the Guidelines ) see the IMOS website at: Also refer to the existing IMOS NSIPs see The NSIP must be in the following template and contain the information set out below: Overview: IMOS Node: Lead Institution: Node Leader: Collaborating Institutions: Western Australian IMOS University of Western Australia Prof. Charitha Pattiaratchi School of Environmental Systems Engineering The University of Western Australia 35 Stirling Highway, Crawley, 6009 Tel: (08) chari.pattiaratchi@uwa.edu.au CSIRO Marine and Atmospheric Research Australian Institute of Marine Science West Australian Marine Science Institution Curtin University of Technology Murdoch University Edith Cowan University Department of Environment and Conservation, WA Department of Fisheries, WA Intergovernmental Oceanographic Commission West Australian Global Ocean Observation System (wagoos) Northern Territory Government

2 1. Introduction: Socio-Economic Context: Overview South-west Australian waters North-west Australian waters Specific Decision Making Issues Uncertainties related to regional oceanography: Design criteria for offshore structures From socio-economic context to science challenges Scientific Background: Large Scale Context Oceanic drivers of marine and terrestrial climate in northwest Australia Regional Oceanography Shelf processes: Northwest Cape to Southwest Cape Leeuwin Current eddies and their interaction with the shelf waters Climate variability of the Leeuwin Current and eddy field Biogeochemistry off the west and southwest Western Australia coasts Impacts of physical processes on ecosystems and productivity Benthic Environment Shelf processes in the northwest region (Darwin to Northwest Cape) The Tidal regime Internal tides Wind driven circulation and upwelling Baroclinic (density driven) circulation The Biological Environment Science Questions to be addressed by the node How will the node activities fit within a national IMOS? Pre-existing observations: : Non-IMOS: National/State wide networks North-west Australian waters South-west Australian waters IMOS Observations HF radar (Australian Coastal Ocean Radar Network, ACORN) Shelf moorings (Australian National Mooring Network, ANMN) Passive Acoustic Observatory (ANMN) National reference stations (ANMN) Ocean gliders (Australian National Facility for Ocean Gliders, ANFOG) Rottnest Island Ferry temperature data (Ships of Opportunity, SOOP) Available Data Streams (emarine Information Infrastructure, emii) What observations does the Node require during , and how will they address the research questions? Observations required by the node; Northern Australian Waters Continuous Plankton Recorder survey between Carnarvon and Fremantle (SOOP) How Observations will address science questions Implementation Plan July 2009 to June 2013: Describe how data provided by IMOS will be taken up and used by the Node Describe what impact the IMOS observations will have regionally, nationally and globally: Governance, structure and funding: Scope of the WA IMOS Node s responsibilities Structure and frequency of meetings of the IMOS Nodes IMOS Steering Committee WAIMOS Committee Structure References

3 1. Introduction: This proposal has been prepared in response to the call by the IMOS office for Node science and implementation plans for the maintenance and enhancement of marine observation infrastructure in Western Australia. The aims of this proposal are to (1) expand the deployment of infrastructure to the unobserved areas of northern waters of Australia, including waters offshore Western Australia and the Northern Territory; and (2) to maintain/enhance existing NCRIS (National Collaborative Research Infrastructure Scheme) infrastructure along the south-west of Australia. Because of the mixture of new (northern Australia) and existing (south-west Australia) the proposal has been divided into the two marine regions. A greater emphasis is made in the proposal for northern Australia because of the pre-existing science plan and associated rationales for the south-west Australian region under the formative WAIMOS regime, and also the recent priority assigned to northern Australia by the Ministerial statements associated with the release of EIF (Education Infrastructure Fund) funds in May of 2009 (The Commonwealth budget provided funds for the extension of IMOS and the enhancement of observing systems focused in northern Australia and the Southern Ocean). The northern waters of Australia, particularly the Kimberley, are recognised as among the world s most pristine and ecologically diverse regions where the scientific knowledge on the marine environment is relatively poor. It one of the most unexplored regions of the Australian continent and is currently the focus of both intense marine biodiversity interest and large industrial activity associated with exploration and extraction of oil and gas. The two geographic regions are connected through the propagation of the boundary current signal around Australia as discussed below. Under the IMOS structure, the deployment of infrastructure will be undertaken through the IMOS facilities. Through this proposal, the node activities in both Western Australia and Northern Territory are proposed to be integrated and administered through the Western Australian node (WAIMOS). The strategic goals of IMOS are to assemble and provide free, open and timely access to streams of data that support research on: The role of the oceans in the climate system; and The impact of major boundary currents on continental shelf environments, ecosystems and biodiversity. The observing program is designed to: provide the long term context for research into environmental change in the ocean; allow specific research studies to be conducted in a global, national and regional context; and allow oceanographic and associated biological phenomena to be investigated at a geographic and temporal scale that has hitherto been extremely limited. This proposal is based on the above goals with a strong integration component. The major boundary currents around Australia include the East Australian Current (EAC) along the east coast, Leeuwin Current (LC) along the west and southern coasts and Flinders Current (FC) along the southern coast. Along the southern coast of Western Australia, the FC flows westward, offshore of the Leeuwin Current. There is no specific boundary current in the northern region, although arguably the poleward Indonesian Throughflow (ITF) may be considered as the boundary current as it impinges on the continental slope and likely interacts dynamically with nearshore domains. This proposal is concerned with the northern, west and south coasts of Australia where the Leeuwin Current is the dominant influence. Although Ridgway and Condie (2004) described the Leeuwin Current as the longest (~5500 km) boundary current in the world extending from North-West Cape to Tasmania, the LC signal originates from the northern region of Australia extending its influence to over 8000 km and influencing more than 2/3 of the continental slope and shelf regions of Australia (Figure 1). Thus we may conclude that the Leeuwin Current perhaps has the most dominant influence of all Australia s boundary currents on the nation s marine environment. The LC plays a dominant role in controlling the marine life and climate of the western and southern regions of Australia. For example, the presence of tropical marine organisms along the west coast of Australia has been attributed to the LC (Maxwell and Cresswell, 1981). The LC also plays an important role in the life cycle of the southern blue fin tuna (Thunnus maccoyii) with economic implications in Port Lincoln, South Australia; in the distribution of seagrass and algae; coral spawning and distribution; western rock lobster recruitment cycles; coastal scallop and fin fish stocks and sea bird distributions (see Pearce and Walker, 1991). Similarly, the higher winter air temperatures and rainfall in the region, compared to similar latitudes elsewhere, may to a certain extent be attributed to the LC 3

4 (Weaver, 1990; Telcik and Pattiaratchi, 1998). Telcik (2002) showed that ~30-35% of rainfall along the southern states of Australia (WA, SA and Victoria) is influenced by north-west cloudbands, which are in turn influenced by Sea surface temperature (SST) off the NW of Australia. The inter-annual variability of the LC is controlled by the ITF through the Pacific/Indian ocean wave guide. Here, El Niño-Southern Oscillation (ENSO) signals propagate from the western Pacific Ocean to the north of the Western Australia and are then transmitted along the west and southern coasts of Australia. This results in a stronger Leeuwin Current during La Niña events and a weaker current during El Niño years (Pattiaratchi and Buchan, 1991; Feng et al., 2003). The seasonal LC signal originates from the Gulf of Carpentaria/ Arafura Sea. Here, there is a seasonal increase in sea level (~40cm) resulting from the monsoon winds. This sea level elevation is released when the winds change to SE trades (K. Ridgway, pers. comm.). The proposed observation system has been designed to monitor the the Leeuwin Current and its influence on the continental shelf environments, ecosystems and biodiversity with a very strong integration component of IMOS which comprises also Bluewater and Climate, South Australia and Tasmanian nodes of IMOS. This integrated approach is reflected in the latitudinal sequence of monitoring locations along the path of the LC as follows: The mooring pair in the Arafura Sea (Figure 1) are designed to capture the seasonal signal originating from this region. The respective ITF line is designed monitor the Indonesian Throughflow (ITF) using a combination of shelf and deep moorings(together with the Bluewater and Climate Node) which controls most of the inter-annual signal. The Kimberley and Pilbara lines, located on contrasting physical environments, are designed to examine the influence of the ITF on the shelf environments, ecosystems and biodiversity. The Two Rocks transect, already established, is located approximately half-way (fortuitously) along the LC signal between the Arafura Sea and Tasmania. The Southern Australian node, already established, links the southern part of the signal. The proposed mooring line along the southern tip of Tasmania completes the monitoring line.(add to map). Figure 1: The influence of the north-west Australia in controlling the Leeuwin Current signal around Australia. The inter-annual variability is controlled by the Indonesian Throughflow whilst the seasonal signal orginates from the Gulf of Carpentaria (K. Ridgway, pers comm.). The white lines indicates the cross-shelf transect locations in the northern region (Arafura-Wessels Pair, Indonesian Throughflow Line (ITF), Kimberley and Pilbara); west coast (Two Rocks) and South Australia (Kangaroo Island). 4

5 The mooring line at Two Rocks is supplemented by cross-shore glider tracks and HF Radar systems. The Kimberley and Pilbara lines also includes Slocum glider tracks. 2. Socio-Economic Context: 2.1. Overview At the broadest level, the socio-economic context for the WAIMOS Node Science and Implementation Plan and the expansion into Northern Australian waters is described in the Australian Government s Oceans Policy Science Advisory Group stakeholder consultation paper A Marine Nation: National Framework for Marine Research and Innovation (November 2008): Australia is a marine nation, an island continent with more than seventy percent of its territory in the marine realm. The marine domain is crucial to our economy, through its resources and maritime transport supporting international trade, and is critical to our national security. Moreover, Australia s coasts and oceans host some of the most iconic marine life and marine habitats on the planet, and are a source of national pride and identity. The surrounding oceans play a vital role in Australia s highly variable climate, and its coasts and oceans are vulnerable to climate change. How Australia utilises, manages and conserves its marine industries and marine environmental assets for maximum economic, environmental and social outcomes is of critical value to its future wellbeing and prosperity. Recognition of the role played by sustained ocean observations in enabling the outcomes described in A Marine Nation has led the Australian Government to allocate an additional $52 million to enhance and extend the existing integrated marine observing system (IMOS) research infrastructure. 1, 2 This funding was provided in the Federal Budget in May 2009, under the Marine and Climate Super Science initiative, is for the period July 2009 to June The IMOS Board was required to invest the first $8 million by 30 June 2009, and is required to develop, by 28 February 2010, a final plan covering the full $52 million of Commonwealth funding, plus a similar amount of co-investment in the new infrastructure. In allocating the additional funding the Australian Government has placed specific emphasis on the Southern Ocean and northern Australian waters, particularly the region between North West Cape to Darwin. In addition to the expectation of co-investment from other parties, there is a particular restriction on the application of the Australian Government funding for IMOS in that it can only be used for research infrastructure, and is not applicable to research projects that use the infrastructure. IN addition, all IMOS data must be made publicly available. However, for the IMOS research infrastructure to fulfil its intended purpose, it is essential that the observations and data streams that it yields are used as inputs into productive research, the outputs of which will help achieve the economic, environmental and social outcomes identified in A Marine Nation. The process used in constructing this WAIMOS Node Science and Implementation Plan has therefore been to identify particular opportunities and challenges related to Australia s northwest waters where research based on IMOS observations would have a high potential for generating such outcomes. Referring specifically to economics, A Marine Nation states: The full economic, environmental and social value of Australia s coasts and oceans is indeterminate. However, in terms of tangible economic value it is known that Australia s marine sector contributes significantly to the national economy (at least 4% of GDP and growing faster than other sectors), through energy and food production, recreation and tourism. 1 IMOS was first funded in 2006 under the then current National Collaborative Research Infrastructure (NCRIS) strategy. IMOS is a collaborative organisation managing a distributed set of equipment and data-information services which collectively contribute to meeting the needs of marine climate research in Australia. The observing system provides data in the open oceans around Australia as well as the coastal waters. 2 Since the data streams primarily provide the long-term context for research into environmental change in the ocean, they are predominantly intended for research use. The data may be relevant to applied research directed at issues affecting industry, but are not expected to be applicable as direct inputs in short-term business decision-making. 3 The funding for this marine and Climate Super Science Initiative is to be administered under, but remains separate from, the Education Infrastructure Fund (EIF), the successor to the former NCRIS strategy. 5

6 Moreover, tangible economic value of coasts and oceans extends well beyond that of the major marinebased industry sectors, such as fishing, shipping and offshore petroleum. For example, in the report Economics of Australia s sustained ocean observation system, benefits and rationale for public funding (August 2006), the benefits to various sectors of the economy, where it could be demonstrated that more effective decisions could be derived from sustained ocean observations and related forecast systems has been estimated to show an annual benefit $616.9 million, for an annual cost $27.3 million for improved ocean observations (a benefit cost ratio 22.6). 4 A sensitivity analysis indicated that, under any likely scenario, the ratio of benefits to costs remains highly favourable. Considering the longer-term forecasting in relation to climate change, A Marine Nation refers to the critical link between oceans and Australia s climate: Droughts and floods, including the prolonged drought currently underway in parts of Australia, have a major impact on Australia s economic, social and environmental wellbeing. To respond to the challenges and opportunities of Australia s highly variable climate, better climate forecasts based on improved observations and understanding of the ocean are essential. The impacts of climate change will be felt both on land and in the oceans, with efficient and effective adaptation depending on knowledge of the future changes in temperature, rainfall and sea-level rise. At the national level, A Marine Nation identifies the major opportunities and challenges in exploration, exploitation and conservation of marine resources, noting that Although complex and interlinked, these opportunities and challenges can be grouped into five distinct categories: Opportunities for increased economic and energy security from marine and subsea resources; Conservation of marine biodiversity and ecosystem services; Management and protection of the marine coastal environment; Climate change; and National security and safety at sea. Part of the complexity in addressing these challenges is that responses are increasingly constrained by international treaties and conventions, often further constrained by national policies and priorities. The compounding difficulty that governments and industry sectors must confront in addressing these challenges and opportunities, especially when dealing with West Australian waters, is lack of sound knowledge on which to base their decisions South-west Australian waters In the first phase of IMOS, investment in Western Australia was focussed in the South West of the State. The main data streams from the WA IMOS west and southwest observation programs are centred adjacent to the coastline of Perth metropolitan, a city of over 1.5 million people many of whom are located close to the ocean. The ocean plays very important role in the society providing a recreational amenity as well as economy through marine based industries. The Australian Defence Forces conduct a range of military training, research and preparatory operations in the Region. Training occurs within Commonwealth waters at the Western Australia Exercise Area (WAXA) situated off the Perth canyon. Shipping is a vital industry for southern Australian economies and many ships transit through the region to and from the eastern seaboard of Australia. The Leeuwin current system and its climate variability have crucial impacts on most of the marine based industries, such as commercial and recreational fishing; defense, marine tourism and recreation, petroleum exploration and production, ship building, ports, and shipping. For example, the southward transport of water via the Leeuwin Current transports tropical and subtropical species which are mixed with temperate species to form diverse and unique biological communities. The region is home to the western rock lobster fishery, which is Australia s largest single species fishery with catches ranging between 8,000 and 15,000 and valued at more than $250 million. The Leeuwin Current also acts as a conduit to the migration of the southern bluefish tuna which is a very profitable aquaculture industry in Port Lincoln, South Australia. 4 This figure was estimated the Australian Bureau of Agricultural and Resource Economics (ABARE) for the Australian Academy of Technological Sciences and Engineering and the Western Australian Global Ocean Observing System Inc., and is described in the report Economics of Australia s sustained ocean observation system, benefits and rationale for public funding (August 2006). 6

7 This region also supports local, national and internationally important gazetted and prospective Marine Protected Areas and other forms of marine reserves (eg in and around the areas of Shark Bay, Cervantes- Jurien Bay, Rottnest Island, Marmion, Shoalwater Islands/Warnbro Sound, and the SW capes region). These State-based high conservation zones sit within areas identified for Australia's National Representative System of Marine Protected Areas (NRSMPA) under the IMCRA framework (IMCRA - Interim Marine and Coastal Regionalisation for Australia), consistent with Australia's national oceans policies. Australia's national Oceans Policy and its bio-regionalisations have identified large areas off S-SW Western Australia as important prospective areas for conservation at the national level. Boundary and coastal counter currents and the oceanographic processes within these various State and Commonwealth conservation zones, as monitored under WAIMOS, are key factors in the transport of waters, associated biomass and biota into and out of these areas and have a strong influence on their ecological characteristics. The establishment and maintenance of long-term oceanographic time series data sets within the current context remains a high priority at State and National institutional levels. With the advent of Ecosystem Based Fisheries Management (EBFM), the need to assess ecological change across a range of spatial scales has resulted in an intensification of research effort in search of cost effective design and indicators of environmental impacts. The WAMSI science program in Western Australia is focussed on understanding ecological change. Both WAMSI node 1 and 4 specifically address the underlying processes that structure temperate, kelp and sessile invertebrate -dominated benthic communities. WAMSI programs and focus on indicators of community shifts that may affect the sustainability of benthic fisheries, like the Western Rock Lobster and the abalone. These studies will direct state government through Fisheries WA and Department of Environment and Conservation in the design and implementation of long term monitoring programs, and the management of benthic fisheries 2.3 North-west Australian waters In response to the federal government directive to improve coverage in Northern Australian waters, WAIMOS interests will expand north to cover the region between the North West Cape and Darwin. This decision is in response to increased development in the Northwest; in particular, Oil and Gas exploration, and mining activities. The impact of paucity of knowledge on decision-making has been taken up in the report A turning of the tide: science for decisions in the Kimberley-Browse marine region (August 2008), commissioned by the Western Australian Marine Science Institution (WAMSI). 5 On a basis of wide consultation, the report presents the argument that it is essential to raise the level of marine science knowledge, because: 1. Its absence can impair decision-making by stakeholders to the serious detriment of the environmental, economic, social and cultural values of the region. The risks for decision-makers of not having sufficient and reliable data on which to consider their decisions can be substantial, particularly when the data are as sparse as they are in the Kimberley- Browse marine region. For example, the Environmental Protection Authority makes recommendations which, when adopted, may have legally-binding conditions. It needs to have a high level of confidence in the science about risks and impacts when assessing development proposals. 2. Without this level of confidence, there is a high probability that decisions will have short time horizons, be costly and iterative as previously unknown problems needing control emerge. The costs of unnecessary delays in development decisions, conflict, loss of confidence in public institutions and community dissatisfaction can be greatly assisted by all relevant stakeholders together contributing a higher level of science understanding to leaders and decision-makers. This research needs to be regional as well as location-specific to enable decision-makers to consider the regional significance of their decisions. A Marine Nation identifies the Kimberley Coast as one of the Australian ocean and coastal regions containing iconic treasures with stunning biodiversity, much of which is endemic to the region, and still largely unknown. However, this notable lack of knowledge extends well beyond the immediate region of the Kimberley Coast to apply to the whole region of Australia s northwest waters. 5 This report encapsulates nine months of stakeholder consultations including A Kimberley-Browse Marine Science policy summit, held at the University of Western Australia in March 2008, that drew together policy-makers, scientists, users, local communities and not-for-profit organisations, representatives from the Commonwealth and State governments, the private sector and the four public universities in WA. Related consultations held with over 50 people covered the same multi-jurisdictional and multidisciplinary landscape. 7

8 The particular concern engendered by this lack of knowledge is that the region is on the threshold of change. As noted in A turning of the tide, the Kimberley-Browse marine region currently supports a range of industries including marine-based tourism, commercial fishing, aquaculture (mainly pearling) and mining. The region s ports ship cattle and mineral products, support large cruise ships, charter, pearling and offshore supply vessels, and import commodities. However, dramatic changes are already taking place with very large reserves of natural gas and petroleum discovered at offshore locations in the Browse and Bonaparte basins and other offshore fields. Resource companies are seeking approvals for the exploitation of these oil and gas reserves. In addition, location of renewable energy sources such as tidal power has been proposed for the Kimberley region as well as strategic plans to protect and manage Indigenous heritage, environment and tourism values. All of these will lead to rapidly changing social and economic issues so that policy and management decisions will have to be made in the near future in order to maximise, in the words used in A Marine Nation, the dividends from Australia s coasts and oceans, including sustaining marine environmental assets. 2.4 Specific Decision Making Issues The problems caused by lack of data can be illustrated by concrete examples, which serve to give particular force to the more general arguments on the need for improved knowledge. The situation with decision-making for biodiversity conservation is particularly well exemplified in the workshop summary A Characterisation of the Marine Environment of the North-west Marine Region. 6 Some of the major uncertainties constraining decision-making at the regional level are listed below Uncertainties related to regional oceanography: While the importance of oceanography at a regional scale is broadly understood, more research is required to improve our understanding of the sources and pathways of currents in the North-west Marine Region. Participants broadly acknowledged the significant influence of the Indonesian Throughflow (ITF) on ecological processes in the North-west Marine Region but there are still very significant gaps in our understanding. More research is required to understand: how currents transport the ITF s waters through the Kimberley and Pilbara marine systems, how long it takes for water bodies to travel through the Region and the effects of the NW monsoon, tides, seasonal and inter-annual variability has upon these systems. Similarly, along the south-west the inter-annual variability in the western Rock lobster catch has been attributed to changes in the regional current systems, particularly the Leeuwin Current. The western Rock lobster fishery is the most valuable single-species fishery in Australia with an annual value up to $350 million. There is an inter-annual variability in the catch which is related to strength of the Leeuwin Current with stronger Leeuwin Current resulting in a higher catch. However, recent low catches have been related to the Indian Ocean Dipole as well as climate change. Thus understanding the different influences which control the Leeuwin Current dynamics are important, in particular: propagation of ENSO signals along the west, and south-west coasts of Australia relative roles of local and remote forcing driving the seasonal, inter-annual, and decadal variability of the Leeuwin Current and its eddy fields? role of topography in the generation of Leeuwin Current eddies? mechanism which the Leeuwin Current and its mesoscale eddies drive the alongshore, cross-shelf exchanges? 6 Summary of an expert workshop convened in Perth, 5-6 September 2007, by the North-west Marine Bioregional Planning section, Marine and Biodiversity Division, Department of the Environment, Water, Heritage and the Arts ( 8

9 2.4.2 Kimberly region: The region is an important area for humpback whales and several species of smaller cetaceans. The workshop highlighted the possibility of humpback whale feeding on tropical krill associated with upwelling around Browse Island, however this observation requires validation. Offshore waters once supported substantial populations of sperm whales and recent acoustic evidence (post-workshop) suggests that blue whales move between Scott Reef and Browse Island during July (moving north) and again in October/November (moving south The Joseph Bonaparte Gulf is an important part of the Northern Prawn Fishery. Significant by-catch is associated with the fishery. Our understanding of the Gulf s natural systems is very rudimentary. In the absence of better information it is difficult to determine what the effects of by-catch on the Gulf s ecology or long term sustainability of the fishery may be Design criteria for offshore structures Deficiencies in data and predictive models also impact on the growth of the oil and gas industry in northwest waters. With projected forward sales already of the order of $100 billion, development is increasingly focused on far-offshore reservoirs towards the edge of the continental shelf. These developments are taking place in waters subject to frequent cyclones, and are calling for the design of long pipelines through waters subject to intense tidal variation. The expenditure that offshore petroleum industry has already made on specific marine observations and data collection in northwest waters far exceeds the most that could be envisaged for an extension of the IMOS research infrastructure into this region. This is because, in contrast to IMOS observations, the data required for engineering design of offshore structures, including pipelines, tends to be three-dimensional and fine-scale. Nevertheless, the petroleum industry also requires broad-scale data in which IMOS observations could play a useful complementary role. There is certainly a pay-off for improving publicly accessible knowledge of the marine environment in this area. As the current large proprietary expenditure indicates, the lack of long-term ocean weather observations, and forecasting models, on which to base engineering design necessitates a more conservative, and therefore more expensive, approach to planning and design that adversely impacts on the region s global competitiveness. In recognition of the need for improving the coordination of oceanographic studies of the Timor Sea, in 2005 WAGOOS (Western Australian Global Ocean Observing System Inc.) hosted the second Timor Sea PIT Project (the Pacific to Indian Ocean Through-flow) Workshop (PIT Workshop, Perth, 18 February 2005). At this workshop, which drew an attendance of around 30, including WAGOOS members and representatives of oil and gas, defence, service industries, government agencies, issues of particular importance to industry operating in these northwest waters were canvassed, including the limited state of knowledge of: Drift along the continental shelf and shelf break Modelling of the hydrodynamics and dispersion of active and non active tracers Benthic boundary layers Internal waves Local eddies shed off reef structures and recirculation onto sensitive parts of the environment. Oceanic Rossby waves propagation westward from the shelf slope Addressing some of these knowledge gaps, such as that concerning local eddies, requires higher resolution data than the IMOS infrastructure is intended to yield. Similarly, data relevant to benthic boundary layers are unlikely to be generated from IMOS infrastructure since it is requires specialised equipment and is not classified as sustained observations. However, IMOS infrastructure could generate data relevant to drift, and dispersion of tracers, and in the monitoring of internal waves. 9

10 2.4.7 From socio-economic context to science challenges With this background, the research described in this plan can usefully be divided into three broad themes, each addressing the needs of a corresponding category of socio-economic activity: Boundary Currents Continental shelf processes Biological response Decision-making in each of these categories of activity is currently hampered by deficiencies in knowledge, and in particular long-term baseline data that could be remedied by the provision of IMOS observations as vital inputs to new research. Continuing the current infrastructure in the south-west and expansion of IMOS infrastructure to northwest waters will serve to remedy these deficiencies, and would provide a remarkable opportunity to make a real difference in the management and development of these regions. In the words used in A turning of the tide: It is rare for leaders to face decisions about the future as complex as those involving the cultural, environmental, economic and social values in the Kimberley. Current needs for energy and food and the development of existing uses challenge leadership to balance these within an awesome natural environment inhabited by Indigenous people for thousands of years. There are opportunities for governments and stakeholders to make exceptional decisions together that will leave an outstanding and unparalleled legacy for existing and future generations; for existing and potential users to contribute to an enduring knowledge of the environmental and social values of the region while seeking economic benefits from it; for Indigenous people, government agencies and stakeholders to build a shared and growing body of knowledge about the region and its sustainable management into the future. 3. Scientific Background: 3.1. Large Scale Context Oceanic drivers of marine and terrestrial climate in northwest Australia The strong seasonal, interannual and decadal variations of the current system off northwest Australia indicate that it is sensitive to climate change (Pattiaratchi et al., 2009). While we cannot say with certainty how the currents will change over the next few decades on the basis of present-day climate modelling, we can be sure that they will change. We already have some clues. There has been a rapid warming of the waters off Western Australia for several decades (Feng et al. 2005). A weakening of the ITF has been observed during the past 40 years (Wainwright et al. 2008) and there is preliminary evidence that the LC has weakened (M. Feng, personal communication). Also, the Trade Winds over the Pacific equator have weakened. We cannot say on the basis of the observations alone whether these are natural fluctuations of the climate system, or a human induced trend. We note however that they are consistent with models of climate change. In a seminal paper entitled, Global Warming and the Weakening of the Tropical Circulation, Vecchi and Soden (2007) state that, The strength of the atmospheric overturning circulation decreases as the climate warms in all IPCC AR4 models.the weakening occurs preferentially in the zonally asymmetric (i.e., Walker) rather than zonal-mean (i.e., Hadley) component of the tropical circulation and is shown to induce substantial changes to the thermal structure and circulation of the tropical oceans. The Indian Ocean generates several modes of climate and weather variation that have an impact on Australia as a whole and on the northwest marine and terrestrial environments in particular. The CLIVAR- GOOS Indian Ocean Panel (IOP) has identified these modes and specified the Indian Ocean Observing System (IndOOS) that can support relevant research. The implementation plan was published in 2006 (see and an update on implementation-status was the cover story in the Bulletin of the American Meteorological Society in 2009 (McPhaden et al, 2009). The modes include: Seasonal monsoon variability and its relationship to Indian Ocean currents Intraseasonal variability, including the Madden Julian Oscillation (MJO) Indian Ocean Dipole (IOD) and teleconnections from El Niño Southern Oscillation (ENSO) Decadal variation and warming trends in the upper Indian Ocean 10

11 Oceanic circulation and distribution of heat (Indonesian Throughflow (ITF, discussed below), shallow and deep overturning cells) Biogeochemical cycling These processes are discussed in detail in Appendix A Regional Oceanography The eastern, tropical Indian Ocean has a complex structure of surface and subsurface currents (Figure 1) together with temperature and salinity distribution that have direct impacts on marine ecosystems and climate of northwest Australia and the wider region. Historically, the region has been a focal point of international marine science since the 19 th century, motivated by documentation of the famous Wallace-line dividing the great diversity of species between Australia and south-east Asia. In the mid-20 th century the region was recognized as the so-called maritime continent, the energy source for much of the tropical, Indo-Pacific atmospheric circulation, the so called Bjerknes Cell.. And within the past 25 years oceanographers have identified it as a critical choke-point in the distribution of heat in the global oceans, and hence in the climate system. We know now that the off-shore oceanographic conditions have a large impact on the marine environment of north-northwest Australia in the nearshore coastal and shelf zones and in Australian EEZ. A case can be made that these are the strongest bluewater-impacts anywhere around the continent. This is due primarily to the influence of the Pacific Ocean and the transmission of its mean state and interannual variation through the channels of the Indonesian Archipelago, Timor Leste and the Australian northwest shelf. The system of ocean currents off the Kimberley and the northwest shelf is illustrated in Figure 1. All these current systems experience strong seasonal to interannual variation, which indicates that they also will experience climate change over decades. Indeed there already is evidence of decadal changes. South Java Current Sumatra Java South Equatorial Current LP Indonesian Throughflow OP Banda Sea TP Holloway Current Darwin Indonesia Indian Ocean Eastern Gyral Current Indo-Australian Basin North West Shelf Broome Exmouth Plateau Port Hedland North West Cape Timor- Leste NT South Indian Current West Australian Current Ningaloo Current Shark Bay Outflow Capes Current Leeuwin Current Shark Bay Perth WA Surface currents Seasonal currents LP Lombok Passage OP Ombai Passage TP Timor Passage ,200 Approximate Scale (km) Copyright Commonwealth of Australia, 2008 Figure 2. Major currents off the Kimberley coast and the northwest shelf (from DEWHA, 2007) A detailed background to the large scale processes which influence the oceanography of the region is presented in Appendix A and only a summary is provided here. The major ocean/shelf current systems in the region include the Indonesian Throughflow (ITF), Leeuwin Current (LC), Leeuwin Undercurrent (LUC), Holloway Current (HC), Ningaloo Current (NC) and Capes Current. 11

12 Indonesian Throughflow (ITF) The ITF is generated by the wind field over the Pacific Ocean, primarily the Trade Winds, which pile up water on the western side of the ocean creating a pressure gradient from the Pacific toward the Indian Ocean. The ITF is sensitive in particular to the easterly winds over the equator. It is a system of currents flowing through the passages between the Indonesian Archipelago, Timor Leste and northwest Australia (Wijffels et al. 2008). The largest single component of ITF flows in the narrow passage between Darwin and Timor Leste (Sprintall et al. 2009). While its net mass (volume) transport is moderate (~10 x 10 6 m 3 s -1 or 10 Sv), the current transports a significant amount of heat because it is the only location in the global ocean where warm tropical water flows from one basin to another, and ultimately has to be replaced by cold water at higher latitudes. The ITF establishes background, environmental conditions for the shelf ecosystems that are unique for eastern boundaries of the oceans, making this region distinct from California and Peru, for example. Firstly, the flow of water from the Pacific allows the spread of species into the eastern Indian Ocean. The thermocline in the region is deep due to the ITF (Wijffels et al. 2008), which limits the supply of nutrient rich waters to the surface. But the dynamics of regional nutrient supply associated with ocean circulation, in particular the role of vertical currents, is not known. The ITF is highly variable on seasonal, interannual and decadal time scales (Meyers et al. 1995; Meyers, 1996; Wijffels and Meyers 2004; Wainwright et al. 2008; Sprintall et al. 2009, and many more listed in Sprintall et al.). The largest and most persistent mode of variation is associated with the El Nino Southern Oscillation (ENSO) phenomenon. This signal, as far as it is observed at this stage, is largely consistent with linear dynamical theory. The coastal (Kelvin) wave guide off Western Australia runs northward (following the 200m depth contour) to a point off north-eastern Papua New Guinea where it joins the Pacific equatorial (Rossby) wave guide. The confluence of waveguides allows large perturbations in depth of the thermocline during the ENSO cycle to propagate into the Indian Ocean and down the West Australia coast. The heatcontent in the deep ocean off northwest Australia is highly predictable out to one year in advance as a consequence of this signal from the Pacific Ocean (Hendon, 2008). There are research challenges associated with this signal. The response of coastal ecosystems along southwest Australia to these perturbations is known, for example in the fish-catch records and other ecosystem indicators (Feng et al. 2009), but the mechanisms that connect the physical environment to the biological responses are not known. Is the seasonal to interannual predictability in the region useful in ecosystem management? Most important, many climate change models do not correctly simulate the confluence of wave guides and consequently do not simulate the observed variations on the Australian northwest coast. This has to be improved before multi-decadal climate predictions can be useful. 12

13 Figure 3: Diagram of Pacific to Indian Ocean Throughflow after Qiu et al. 1999, Northwest monsoon and Gulf circulation pattern during the Northwest Monsoon after Forbes and Church (1983). (sourced from White, 2003) Leeuwin Current (LC) The LC is generated by the formation of a high pressure ridge in the upper ocean near S, and associated eastward currents flowing toward northwest Australia. The current turns southward approaching the coast (under dynamic control of the poleward Kelvin wave guide) and, flows poleward down the pressure gradient along the whole length of Western Australia past Cape Leeuwin. It is the only subptropical poleward flowing boundary current on the eastern side of an ocean in the world. It is a shallow (< 300 m) narrow band (< 100 km wide) of relatively warm, lower salinity water of tropical origin that flows southward, mainly above the continental slope from Exmouth to Cape Leeuwin (Church et al., 1989; Smith et al., 1991; Ridgway & Condie, 2004). The maximum flow of the current is located at about the 500m isobath. At Cape Leeuwin it pivots eastward, spreads onto the continental shelf and flows towards the Great Australian Bight (Figure 1). It is now accepted that the Leeuwin Current signature extends from North West Cape to Tasmania as the longest boundary current in the world (Ridgway & Condie, 2004). The meridional pressure gradient in the southeast Indian Ocean, set up by the Indonesian Throughflow (ITF) in the tropics and by latent heat fluxes (cooling) in the mid-latitude, accounts for the existence of the LC. The source of the Leeuwin Current water is from the tropical/subtropical Indian Ocean from the west and a component from the North West continental shelf. The South East Trade Winds, in the Pacific Ocean, drive the South Equatorial Current westwards advecting warm surface waters towards Indonesia. This results in the flow of warm, low-salinity water from the western Pacific Ocean through the Indonesian Archipelago into tropical regions of the Indian Ocean. The lower density water (lower salinity, warmer) off the north-western Australia and higher density water (higher salinity, colder) off south-western Australia results in a surface slope between latitudes of 15 S and 35 S which is of the ~4 x 10 7 (from north to south), corresponding to a sea level difference of 0.55 m between North West Cape and Cape Leeuwin. 13

14 This first order explanation of the LC does not account for details of either the eastward flows or the Leeuwin Current. The linear theory generates broad currents but in fact both the eastward flows and the LC concentrate in narrow jets. Various hypotheses have been put forward to explain the detailed structure (J. McCreary, personal communication; J.S. Godfrey, personal communication), requiring research based on better observations, modelling and dynamical interpretation. The LC brings tropical waters and species to relatively high latitude along the West Australian coast (Domingues et al. 2007), and creates a unique coastal ecosystem with the central west coast marine ecosystem having been described as a special biodiversity area (Roberts et al. 2002). While this is qualitatively understood (Feng et al. 2009; Pattiaratchi and Woo, 2009), the ability to quantitatively understand and model it is in its infancy. The LC also is highly variable on seasonal and interannual timescales (Feng et al. 2003; Feng et al. 2008). The strong seasonal cycle enhances fresher and warmer tropical waters along the west Australian coast when its poleward flow is maximum (Cresswell and Golding 1980; Smith et al. 1991). The seasonal cycle of the Leeuwin current is driven by a combination of pressure gradient and wind stress, which reinforce one another (Godfrey and Ridgway 1985; Feng et al. 2003). During October to March the Leeuwin Current is weaker as it flows against the maximum southerly winds resulting in transports of +1.,5 Sv, whereas between April and August the Current is stronger as the southerly winds are weaker resulting in transports of up to 7cSv (Godfrey and Ridgway, 1985, Smith et al., 1991). The mean volume transport is estimated to be 3.4 Sv (Feng et al., 2003). The location of the core of the current also changes seasonally in winter the core of the current located close to 200m contour whilst under the action of the southerly wind stress, the Current is pushed offshore. The interannual variation in depth of the thermocline associated with ENSO described above propagates poleward in the coastal waveguide, affecting the entire West Australian coast and into the Great Australian Bight. (Pariwono et al. 1986; Pearce and Phillips 1988; Clarke 1991; Feng et al. 2003). Higher sea level anomalies, warmer sea surface temperatures, and deeper thermoclines are expected along the coast during La Niña years and vice versa during El Niños. The seasonal and interannual variability affect the regional marine ecosystems but the mechanisms that connect physical and biological processes are not well known. The variability of LC indicates that it will be sensitive to climate change in future decades. The LC has the strongest eddy energy among the mid-latitude eastern boundary current systems (Feng et al. 2005). The interannual variations of the LC and its eddy field respond to the El Nino/Southern Oscillation (ENSO) and many of the fisheries recruitments off WA are also associated with ENSO induced interannual variability (Caputi et al. 1995). The LC eddy field has vital influences on the marine pelagic production off the west coast of WA (e.g. Hanson et al. 2005a; Feng et al. 2007; Koslow et al. 2008). The seasonal and interannual variability implies that eddy-dynamics and the current s interaction with ecosystems will change with climate change. The Leeuwin Undercurrent (LU) Initial studies by Thompson (1984, 1987) indicated that there was an equatorward undercurrent flowing beneath the Leeuwin Current (Figure 2). Current meter data from the Leeuwin Current Interdisciplinary Experiment (LUCIE) (Smith et al., 1991) confirmed the observations of Thompson (1987) and indicated that the equatorward undercurrent was narrow and situated between 250 m and 450 m depth contours, adjacent to the continental slope. The LUC is driven by an equatorward geopotential gradient located at the depth of the Undercurrent (Thompson, 1984; Woo and Pattiaratchi, 2008). The LUC is closely associated with the subantarctic mode water (SAMW) formed in the region to the south of Australia. A feature of this water mass, resulting from convection, is high, dissolved oxygen concentration; thus the core of the LUC can be identified from the dissolved oxygen distribution: a dissolved oxygen maximum (252 μm/l) centered at a depth of approximately 400 m (Woo and Pattiaratchi, 2008). Holloway Current (HC) HC is a surface layer poleward flowing ocean current that brings water perhaps from as faraway north as the Banda and Arafura seas, southward over the continental shelf of northwest Australia at the end of the northwest monsoon (D Adamo et al. 2009). A simple view of the generating mechanism is the seasonal south-westerly wind piles up water in the Arafura Sea and Gulf of Carpentaria during the peak monsoon, and 14

15 the current flows southward as the wind relaxes during the monsoon transition. This is seen clearly in satellite altimetry data (Ridgway, personal communication). However, detailed analysis and modelling indicates that the impact of seasonal heating on sea level adds to the overall force balance to generate the full strength of the current (Godfrey and Mansbridge 2000; Kronberg 2004; D Adamo et al. 2009). The HC is particularly important because of its proximity to coastal ecosystems and its potential to provide a mechanism of along-shore bio-physical connectivity along a region of the world that has both high biodiversity conservation value (largely to be explored) and strong economic claims in oil and gas exploration/production. Climate models will have to get this complex generating mechanism right before predictions of the future impact of climate change can be used in regional marine management. The strong seasonal, interannual and decadal variations of the current system off northwest Australia indicate that it is sensitive to climate change (Pattiaratchi et al., 2009). While we cannot say with certainty how the currents will change over the next few decades on the basis of present-day climate modelling, we can be sure that they will change. We already have some clues. There has been a rapid warming of the waters off Western Australia for several decades (Feng et al. 2005). A weakening of the ITF has been observed during the past 40 years (Wainwright et al. 2008) and there is preliminary evidence that the LC has weakened (M. Feng, personal communication). Also, the Trade Winds over the Pacific equator have weakened. We cannot say on the basis of the observations alone whether these are natural fluctuations of the climate system, or a human induced trend. We note however that they are consistent with models of climate change. In a seminal paper entitled, Global Warming and the Weakening of the Tropical Circulation, Vecchi and Soden (2007) state that, The strength of the atmospheric overturning circulation decreases as the climate warms in all IPCC AR4 models.the weakening occurs preferentially in the zonally asymmetric (i.e., Walker) rather than zonal-mean (i.e., Hadley) component of the tropical circulation and is shown to induce substantial changes to the thermal structure and circulation of the tropical oceans. Figure 4: Schematic diagram illustrating the general flow patterns at the continental margin of south-western Australia (Woo and Pattiaratchi, 2008). Ningaloo Current (HC) The Ningaloo current flows north along the inner continental shelf between the Leeuwin Current and the coast. A strong, southerly wind stress drives the current (Taylor & Pearce 1999; Woo et al. 2006a), similar to the Capes current along the south-west Australian coast. Taylor and Pearce (1999) used aerial surveys and satellite imagery to observe the Ningaloo current moving north along the Ningaloo reef front, forming a distinct line in the water and separating the coastal waters from the southward flowing LC some 2 km offshore. Studies using field data (Hanson et al. 2005b; Woo et al. 2006b) and numerical modelling (Woo et al. 2006a) found the Ningaloo current inshore of the 50-m isobath, extending from Shark Bay to North West Cape and past Barrow Island. The Capes Current Pearce and Pattiaratchi (1999) defined the Capes current as a cool inner shelf current, originating from the region between Capes Leeuwin (34 S) and Naturaliste, which flows equatorward along the south-western Australian coast in summer and extends northwards past the Abrolhos Islands. The Capes current seems to be well established around November, when winds in the region become mostly southerly because of the 15

16 strong sea breezes (Pattiaratchi et al. 1997), and continues until about March when the sea breezes weaken. Gersbach et al. (1999) showed the Capes current source water was from upwelling between Capes Leeuwin and Naturaliste, which was augmented by water from the south to the east of Cape Leeuwin. Gersbach et al. (1999) described the dynamics of the Capes current, off Cape Mentelle. The continental shelf in Australia s south-west comprises a step structure, with an inner shelf break at 50 m and an outer shelf break at 200 m (Pearce and Pattiaratchi 1999). This bathymetry influences the circulation, especially in the summer. In the summer, the alongshore wind stress overwhelms the alongshore pressure gradient on the inner shelf (depths < 50 m), moving surface layers offshore, upwelling colder water onto the continental shelf, and pushing the Leeuwin current offshore (Figures 5,6). Here, the Capes current is present on the inner shelf and bounded offshore by the Leeuwin current on the lower shelf, with upwelling occurring over the inner shelf break (Gersbach et al. 1999). Numerical model results showed a wind speed of 7.5 ms 1 was sufficient to overcome the alongshore pressure gradient on the inner continental shelf (Gersbach et al., 1999). The Leeuwin current strengthens in the winter, and, in the absence of wind stress, migrate closer inshore, flooding upper and lower terraces (Pearce and Pattiaratchi 1999). Capes Current Figure 5: Ocean colour images off south-western Australia showing the sea surface temperature and the upwelling of cold water onto the Capes current with the associated high chlorophyll concentration. 3.2 Shelf processes: Northwest Cape to Southwest Cape Leeuwin Current eddies and their interaction with the shelf waters Meanders and mesoscale eddies are intrinsic features of the Leeuwin Current. From satellite observations and numerical model simulations, the Leeuwin current is generally associated with mesoscale eddies and meanders (Pearce and Griffiths 1991; Fang and Morrow 2003; Morrow et al. 2003; Feng et al. 2005; Fieux et al. 2005; Meuleners et al. 2007; Rennie et al. 2007; Waite et al., 2007). The LC has the strongest eddy energy among the mid-latitude eastern boundary current systems (Figure 7; Feng et al. 2005). The Leeuwin current becomes unstable as it interacts with changes in the bathymetry and offshore water of different densities, to generate eddies which propagate offshore in particular, off Shark Bay, the Abrolhos Islands, Jurien Bay, Rottnest Island, and Cape Leeuwin (Figure 8). On the seasonal cycle, the LC eddy field is strong during the austral winter and weak during the austral summer, such that the peak eddy energy occurs about 1 month later (July) compared to that of the peak LC transport. This would be expected since 16

17 the eddy field draws its energy from the instability of the LC (Figure 8). Mesoscale eddies form the LC can drive significant cross-shelf nutrient exchanges off the west coast of WA (Paterson et al., 1008), and enhanced concentration of surface chlorophyll a tend to be observed in the warm-core eddies off the west coast (Figure 5), associated with increases in primary production (Waite et al., 2007b; Thompson et al., 2007) and larval transport (Waite et al., 2007; Muhling et al., 2007). Once they detach from the shelf, the LC eddies tend to have deep expression through the water column to depths of 2500 m (Fieux et al. 2005; Meuleners et al. 2007). Figure 9: Long-term mean surface eddy kinetic energy derived from satellite altimeter data (left panel). The right panels (from top to bottom) are seasonal cycle of the Fremantle sea level, Leeuwin Current transport (Geostrophic and Ekman), and surface eddy kinetic energy between Abrolhos and Perth (derived from Feng et al. 2003, 2005, and 2009). 17

18 Figure 8: Ocean colour image showing the eddy structure of the Leeuwin current. The higher chlorophyll water is located on the shelf and is entrained into the Leeuwin current. Figure 9: Time series of Southern oscillation Index (SOI), Fremantle Sea level and Puerulus settlement Index (from Nick Caputi) Climate variability of the Leeuwin Current and eddy field The ENSO related upper ocean variations propagate poleward as coastal Kelvin waves along the northwest to west WA coasts (Meyers 1996; Feng et al. 2003). The waves transmit high coastal sea levels (deep 18

19 thermocline) and induce strong LC transports (4.2 Sv) during the La Niña years, and transmit low sea levels (shallow thermocline) and induce weak LC transports (3 Sv) during the El Niño years (Feng et al., 2003). A significant linear relationship between the Fremantle sea level and the volume transport of the LC across 32 S on the annual and interannual time scales can be derived. There is also a strong association between ENSO and the altimeter derived eddy energetics, ½(u 2 +v 2 ), averaged between Abrolhos and Perth (Fig. 4). Strong eddy energetics occurred during the La Niña years, e.g. 1996, 1999, and 2000, while weak LC eddy energetics were observed during the El Nino years, e.g. 1994, 1997, and During , the linear correlation between the annual mean Southern Oscillation Index (SOI) and the eddy energy is 0.94, demonstrating the strong sensitivity of the LC system to ENSO. Another important feature of the physical environment in the LC is the strong surface heat loss along the southward flowing warm current. The heat loss is mostly due to the evaporative cooling (latent heat flux) when warm sea surface temperature in the LC meets the cold air temperature in the south and the frequent occurrence of winter storms originated from the Southern Ocean. The evaporative cooling is strong during austral winter, when the LC transport is strong. There are also consistent ENSO-related interannual variations in the surface heat loss the heat loss is stronger during the La Nina years and weaker during the El Nino years. Surface cooling can induce strong vertical mixing which affects stratification in the water column and thus is important in nutrient cycling in the mixed layer of the LC (Greenwood et al. 2007). The region between Geraldton and Fremantle encompasses main fishery region of the Western Rock Lobster which involves some 500 commercial boats and 45,000 recreational fishers. The annual catch varies between 8,000 and 15,000 tonnes and is the biggest single specie fishery in Australia with a total value up to AU$250 million. The lobsters are generally found in water depths < 150 m, with juveniles aged up to 3 years predominating in shallow coastal lagoons <12 m deep, adolescents 4-5 years present in coastal lagoons and deeper offshore waters (0-150 m), whilst mature adults 6 years are more abundant at depths of m (MacArthur et al., 2007). The lobster larvae, known as phyllosoma, hatch in February-March and are transported offshore by ocean currents and are usually located between 300 and 1000 km offshore beyond the Leeuwin Current (Gray 1992). Between August and December (9-11 months after hatching) late-stage phyllosoma larvae undergo a final larval moult into the morphologically distinct puerulus larva and are settled on the reef systems in depths < 35 m. The settlement of puerulus has strong links to the oceanic conditions, and particular, the strength of the Leeuwin Current. Pearce and Phillips (1988) showed that there is a strong correlation between the Southern Oscillation Index (SOI), Fremantle sea level (a measure of the Leeuwin Current strength and the puerulus settlement (Figure 9) Biogeochemistry off the west and southwest Western Australia coasts The LC is a downwelling current which suppresses coastal upwelling off the Western Australia coasts and causes the oligotrophic marine environment. In the oligotrophic marine environment off the west coast of WA, there are surface chlorophyll a concentrations compared to other eastern boundary current systems (with typical value of ~1 mg m -3 ). There has been a recent discovery of late-autumn to early-winter chlorophyll a enhancement in the LC system south of Abrolhos from in situ observations (Koslow et al. 2008), which is also captured by the satellite measurements (Lourey et al., 2006; Feng et al. 2007; Moore et al., 2007). Averaged over the shelf (approximately in the m depth range), consistent late-autumn to early-winter (May-June) peaks of upper ocean chlorophyll a concentrations are observed south of Abrolhos, with peak values of about 0.4 mg m -3 (Figure 7). Offshore of the LC and within about 500 km off the coast, late-winter (July-September) phytoplankton enhancements are generally observed, with winter values of about mg m -3. Further offshore in the oligotrophic, subtropical open-ocean, the chlorophyll a concentration is very low and there is a winter peak of less than 0.2 mg m -3. The September-October chlorophyll a peaks south of 32 S are likely due to the northward migration of the subtropical front, with peak values of about 0.3 mg m -3. On the continental shelf north of Shark Bay, there is the summer (January) chlorophyll a peak, which is driven by upwelling favourable winds (Hanson et al. 2005a). The broad winter (June-October) peak in Figure 7 is likely due to that the box for average is relatively large so that winter peak in the offshore region may contaminate the results. Most of the seasonal cycles are significant compared with the 30% accuracy range. The mechanisms that could drive the seasonal nutrient dynamics in the LC are hypothesized as (Feng et al. 2009): Meridional erosion of seasonal thermocline drives nutrient injection into surface layers; The 19

20 lifting/dropping of the nitrocline can increase/decrease primary production; Both the horizontal and vertical advection related the eddy activities are important in enhancing ocean production in the LC system; In situ nitrification can increase localized production (Paterson et al., 2008); Benthic-pelagic coupling may be an important process on the seasonal cycle. The dynamics and primary productivity of eddies off the Western Australian coast has been studied over the past few years. Some of the earlier results are presented as a special issue of Deep-Sea Research Part II: Topical Studies in Oceanography (Waite et al., 2007a). Here, the physical structure, primary production, and larval fish assemblages in warm-core and cold-core eddy are examined. In general, the warm-core eddies are seen as a crucible for localized nitrate-drive new production, which has a significant impact on offshore production patterns. The cold-core eddies are often upwelling only at depth (e.g., m; Waite et al., 2007a), and at the surface remain largely indistinguishable from the surface oligotrophic ocean. Although the Capes current extends from Cape Leeuwin to past the Abrolhos Islands, the most intense upwelling, and therefore the highest concentration of surface chlorophyll a (Figure 3), occurs between Capes Naturaliste and Leeuwin, as the winds are strongest along this section of the coast compared with the north. Gersbach et al. (1999) found water upwelled from the base of the Leeuwin current contained only slightly elevated nutrients (0.4 μm NO 3 ), compared with the bulk of the Leeuwin current (0.2 μm NO 3 ). In contrast, Hanson et al. (2005) upwelling in the Capes region transported higher nitrate concentrations (> 1.0 μm) into the upper euphotic zone (< 50 m). The nutrients were sourced from the nutricline at the base of the mixed layer beneath the Leeuwin current. Hanson et al. (2005) found that because of the upwelling of higher nutrient water, seasonal upwelling in the Capes region supported high primary production rates. Maximum production rates were 945 mg C m 2 d 1, with the higher depth averages produced at the 50-m contour. Hanson et al (2005) also found that in winter, the stronger Leeuwin current flow, and its interaction with the shelf water upstream of the Capes region, increased the nutrient levels (nitrate levels of ~2 3 μm) in the Capes region; however, compared with summer, the lower subsurface light conditions (lower solar angle and higher attenuation due to storm action) in winter lowered the primary production. Nutrient Dynamics of the Deep Chlorophyll Maximum One feature of note throughout the region is the common dissociation of surface primary production and biomass indices from processes at the pycnocline often controlling the bulk of production (Hanson et al., 2007a). This means that satellite ocean colour data can often be misleading in terms of assessing the mechanisms driving production. Twomey et al (2007) documented significant nitrate-driven production at depth (i.e., in the deep chlorophyll a maximum) off the west and south coasts respectively, which was not identifiable from satellite, and occasionally did not even result in an increase in local nutrient concentrations, due to the rapid rates of uptake by phytoplankton. It is this scale of event, termed cryptic upwelling (Twomey et al., 2007) which may control production patterns on the WA coast, but such processes may remain inaccessible without vertically stratified measurements. In contrast to the west coast, the south coast of WA has had very little oceanographic field data collected. Twomey et al (submitted) identified wind-driven cryptic upwelling as a key process driving vertical nitrate fluxes and productivity pulses, especially at the shelf break, but also in deep shelf waters. Neither of these signals was in any way evident in satellite data, suggesting a significant discontinuity between deep processes and ocean colour measured at the surface. One other issue that remains largely unaddressed throughout the region is the critically important light-driven process of fluorescence quenching of phytoplankton pigments, which imposes an apparent diurnal and depth-cycle on the interpolated chlorophyll a signal. Any time-of-day bias in sampling, either from ships or satellites, is likely to be biased by such processes. Both cryptic upwelling and fluorescence quenching are likely to be examined in great detail through the IMOS data sets, a critical calibration facilitating the linkage between physical and biogeochemical analyses. 20

21 Figure 10: Seasonally-averaged sea surface chlorophyll a concentrations in the southeast Indian Ocean calculated from SeaWIFS monthly climatology data ( ). The bottom bathymetry is denoted for the 50, 200, and 1000 m isobaths (adapted from Feng and Wild-Allen 2007) Impacts of physical processes on ecosystems and productivity. Interaction between Leeuwin Current, Capes Current and coastal currents during the summer The Leeuwin Current and Capes current creates a frontal system. Here, the warmer, lower salinity southward flowing Leeuwin Current interacts with the cooler, higher saline northward flowing Capes Current creating region of high horizontal shear and thus intense mixing (Figure 8). Figure 11: Sea surface temperature image overlain by currents measured by a shipborne ADCP in November The northward flowing Capes current is shown in black arrows and the southward Leeuwin Current by red arrows. The HF Radar coverage of the CODAR and WERA systems are also shown. 21

22 Higher density plumes transporting nearshore and shelf water offshore along the continental shelf The region experiences a Mediterranean climate with hot summers and cold winters. During the summer months the inner continental shelf waters increases in salinity due to evaporation. In winter as this higher salinity waters cool its density is higher than offshore waters and a gravitational circulation is set-up where the inner shelf water are transported as higher salinity plumes into deeper waters (Figure 12). Temperature Salinity Figure 12: CTD transects offshore Ocean reef showing cooler, higher salinity flowing offshore as higher density plumes. Rottnest Island wake The redistribution of nutrients, pollutants, and sediments in the wake of islands or headlands has important implications in fisheries, pollutant dispersal, and sediment transport. During the past few decades, special attention has been given to wake structures, and many studies have attempted to achieve a better understanding of the flow structure within the island wake regions (e.g. Wolanski et al., 1984; Pattiaratchi et al., 1987; Tomczak, 1988; Alaee et al., 2007). Field and numerical model studies in the summer wake of Rottnest Island by Alaee et al. (2007) indicated that secondary circulation, induced by flow curvature along the western end of the island was responsible for the generation of upwelling of cold water onto the shelf which was advected northwards by the prevailing currents resulting in a dome structure to the north of the island (Figure 15). Figure 13: The doming of isotherms to the north of Rottnest Island due upwelling generated by flow curvature (Alaee et al., 2007). 22

23 The Perth Canyon, upwelling and Whale aggregations The interaction between shelf and slope current systems causes localised flow patterns, which influence the ecology in the canyon vicinity. Compared with their nearby surroundings, submarine canyons have higher biodiversity and biological productivity (Hickey 1995). This is often attributed to upwelling at the canyon site enriching the photic zone with nutrients. The Perth Canyon is an extension of the Swan River system, and cuts into the continental shelf west of Perth and Rottnest Island within the Mentelle sub basin. The Perth Canyon, which starts at the 50-m contour, is ~100 km long and ~10 km wide near the canyon head, and reaches depths more than 1000 m. It is 3 km deep at the shelf slope, and cuts 4 km deep into the continental slope. The canyon head refers to the canyon s shoreward section, and the tip refers to the head s closest point to the coast. The canyon bends at 10 km and 50 km from the tip, and branches south at 40 km and 50 km. At the canyon head, the depth plunges from 200 m to 1000 m, with the canyon mouth opening onto the abyssal plain at a depth of 4000 m. Hence the Perth Canyon can be described as long, deep, narrow, steep-sided, and intruding into the continental shelf. Rennie et al. (2007) have demonstrated that the Leeuwin undercurrent interacting with the canyon generated clockwise eddies (upwelling favourable) within the canyon (Figure 13). As a result of these circulation patterns within the canyon, the canyon supports a high primary and secondary production resulting in the whale (pygmy blue whales) aggregation during the summer months (Rennie et al., 2008). Eddies caused regions of upwelling or downwelling, with deep upwelling stronger in the canyon than elsewhere on the shelf. Upwelling alone was insufficient to transport nutrients to the euphotic zone because the canyon rims are deep. Increased upwelling, combined with entrapment within eddies and strong, upwelling-favourable winds caused the high primary productivity in the canyon. The Leeuwin current formed a strong barrier to the water upwelling to the surface. The model results also suggested upwelling at the canyon head occurred when a clockwise surface eddy was centered over the south rim, whereas an eddy (either clockwise or anticlockwise) centered on the north rim caused net downwelling. Figure 14: Example flow patterns in the Perth Canyon at the surface, 200 m, and 500-m depths. Shading indicates temperature, with lighter shades showing the upwelling regions (from Rennie et al., 2008). The results from the boat surveys (Figure 14) revealed whales were found in a water depth range of m along the canyon rim, but were more concentrated along the northern plateau (Figure 2.8). The mean whale resighting period (from boat surveys) was 21.3 ± 8.3 days (± 95% CI), which suggested the whales stayed within or near the canyon for between two and four weeks. Satellite tags gave additional information on several whales movements (Jenner and Gales, unpublished data). Of four whales that were tagged, one stayed in the canyon for eight days in March 2002, foraging around the rims and the canyon head. A whale tagged in Geographe Bay around 1.5 south of the canyon in December 2002 was found 43 days later in the subtropical convergence zone at 122 E. The whale tagged in late March 2004 spent 16 days traversing a region between the canyon (32 S) and the shelf break at 31 S. The whale tagged in late March 2004 traversed the shelf north to the Abrolhos Islands, but farther offshore, travelling about 425 km in seven days. Many dolphins were also seen in the canyon, as well as other whales, including beaked, sperm, minke, Risso s, humpback, and southern right whales. Acoustic detections implied true (Antarctic, B. musculus intermedia) blue whales overwintered around the canyon and headed south in mid-october. 23

24 Figure 15: Sightings of pygmy blue whales from boat surveys (from Rennie et al., 2008) Benthic Environment At regional scales, the distribution of species and the structure of benthic marine assemblages vary with latitude. The oligotrophic coastal waters of Western Australia (WA) support highly speciose and endemic benthic assemblages, yet spatial and temporal patterns in benthic structure are currently poorly known. We recently examined benthic assemblage composition along a latitudinal gradient of 28.5 to 33.5 S and a depth gradient of 14 to 62 m, on subtidal reefs in warm-temperate WA (Smale et al. in press). In the last decade or so, quantitative information on the distributions and ecologies of macroalgae (Wernberg et al. 2003), echinoderms (Vanderklift and Kendrick 2004), molluscs (Vanderklift and Kendrick 2004, Wernberg et al. 2008), historical and extant reef corals (Greenstein and Pandolfi 2008) and fish (Ayvazian and Hyndes 1995b, Tuya et al. 2008) have been collected from various locations along the temperate latitudinal gradient (~35-28 S). While these studies have substantially contributed to our knowledge of the benthic system, they are spatially limited as they were all conducted by SCUBA divers in shallow water (i.e. < 20 m depth). However, only ~5 % of the total area of WA s continental shelf lies at depths of < 20 m, whereas ~70% of the entire shelf lies in depths of m (Kendrick, unpublished data). Thus, the majority of the shelf habitat has been greatly under-sampled. We propose to address this major limitation through the use of the AUV facility at University of Sydney and through targeted transects in deeper waters (20-80 m) from the west coast of Western Australia. We intend to sample Cape Naturaliste, Rottnest Island/ Whitford transect, and the Houtmans Abrolhos. The transects would focus on the kelp-coral transitions in these regions Also the WAIMOS benthic monitoring program is part of a larger IMOS focus on the effects of climate change and climate variability on benthic communities on the continental shelf, with a particular focus on rocky reefs. The strong focus on benthic reef systems is justified because: much of Australia s marine biodiversity is vested in benthic reef assemblages; reefs are among those ecological systems most sensitive to environmental change because they support sessile and sedentary individuals that are unable to relocate once established; dominant species on reefs are largely long-lived species whose dynamics integrate ocean conditions over periods of time from several months to several years; they have a disproportionate contribution to marine economic activity in supporting key fisheries and offering great potential for bioprospecting; they have been much understudied give difficulties of access and obtaining highly resolved georeferenced data beyond diving depths; 24

25 reefs have prominent physical features that make them ideal for precision monitoring using exactly matching image mosaics through time, as can be generated by state-of-the-art AUV technology. The proposed work both within WAIMOS and as a coordinated national IMOS focus has a heavy reliance on AUV technology. The application of this technology and related image processing and analysis are maturing and clearly have the potential to reduce the cost per observation, especially when fully operationalised in a long-term program. Initial pilot work with the AUV through IMOS has strongly delivered the proof of concept, and the proposed work develops from the strengths of the initial outcomes Shelf processes in the northwest region (Darwin to Northwest Cape) Physical characteristics of the systems in the region The northern region of Australia may be divided into 4 different regions based on their physical characteristics and thus may be considered to be distinct bioregions, with distinct links to the structure of the offshore (Bluewater) currents. System Summary of system characteristics Pilbara: Broome to North-west Cape tropical arid climate, transition between ITF and Leeuwin Current dominated areas, Main region of Holloway and Ningaloo current influence predominantly tropical species, high cyclone activity with frequent crossing of the coast, transitional tidal zone, high internal tide activity, large areas of shelf and slope, high evaporation rates dry coast with ephemeral freshwater inputs. Kimberley: Broome to Cape Londonderry tropical monsoonal climate, strong influence from Indonesian Throughflow, predominantly tropical Indo-Pacific species, moderate off-shore tropical cyclone activity, large tides, freshwater input from terrestrial run-off, turbid coastal waters (i.e. light limited systems), dominated by shelf environments, predominantly hard substrates in inner to mid-shelf environments, has a number of shelf-edge atolls (i.e. Scott Reef, Rowley Shoals). Bonarparte: Cape Londonderry to Darwin tropical monsoonal climate, strong influence from ITF predominantly tropical Indo-Pacific species, moderate off-shore tropical cyclone activity, medium tides in amphidromic system, freshwater input from terrestrial monsoonal run-off, particularly from Joseph Bonaparte Gulf (Ord river) turbid coastal waters (i.e. light limited systems) Carpentaria: Darwin to Torres Strait tropical climate, moderate off-shore tropical cyclone activity, lower tides, diurnal in Gulf of Carpentaria reduced freshwater input, mainly shallow water regions. 25

26 The Kimberley region is generally considered to be a source region of the Leeuwin Current and is a region of energetic tides (largest tides in the world adjacent to an open coastline) and associated nonlinear internal waves (Holloway, 1995), weak wind forcing in the absence of tropical cyclones (Church and Craig, 1998), low surface wave energy (neglecting those generated by tropical cyclones) and strong wintertime evaporative fluxes (Holloway, 1995). The region experiences a tropical monsoonal climate with a wet season lasting from November to March and a dry from April to October. Annual rainfall ranges from 1500 mm in the sub-humid north-west to 350 mm in the semi-arid south. Monthly temperatures average between 25ºC and 35ºC (Masini et al., 2009) The Tidal regime In contrast to southern Australia which is characterised by relatively small tidal range, northern Australia experiences a macro-tidal environment, particularly in the north-west which has the largest tidal range for a coastline facing an open ocean (Figure 2). This is mainly due to the fact that the continental shelf width is such that tidal resonance occurs resulting in amplification of the tidal wave propagating from the Indian Ocean (Figure 3). Although the region experiences high tides there are large changes across the region. For example, the tidal range is relatively small off North-west Cape (~ 2m) and then increases eastward reaching a maximum in the Kimberley region (Figure 2). There is a marked decrease in the tidal range off Cape Londonderry due to the presence of a M 2 tidal amphidromic system (Figure 3a). The tidal range then increases in Joseph Bonaparte Gulf. These changes in tidal range are also reflected in the tidal current ellipses with indicate regions of strong currents and regions of relatively weaker currents (Figure 3b). These variations in current amplitudes have significant influence on bottom stress which influences the coastal ecosystem. Regions of strong currents have high sediment transport capacity resulting in turbid waters and also high bottom stress. The turbid water influences the phytoplankton production whilst the bottom stress controls the benthic habitats. Thus a precise understanding of the tidal dynamics, which is currently lacking, is one of the basic requirements for defining the characteristics of the marine environment of this region. Figure 6 Maximum tidal range around the Australian continent (from Peter Harris). Another major feature of the macro-tidal systems is the generation of tidal fronts. Fronts are distinctive oceanographic features that mark the boundaries between water bodies with different characteristics. They are lateral zones above or below which there is localised and sometimes vigorous vertical movement of water. The temperature differences between water masses which cause tidal fronts are related to the amount of mixing that takes place within shallow and deeper waters. In shallow water, the turbulence generated by the sea bed is sufficient to mix the vertical water column in contrast in deeper waters the tidal currents usually weaker and the bottom stress is unable to vertically mix the water column resulting in a 26

27 stratified water column, particularly during periods of high solar radiation. The location of the tidal fronts may 3 be defined by the Simpson-Hunter criterion h u o where h is the water depth and u o is the velocity. At tidal fronts, strong vertical mixing and transport release nutrients into the surface waters which in combination with higher light levels increases phytoplankton production along the front. Increased zooplankton and larval fish concentrations have also been observed in these areas. These concentrations are exploited by fishes and marine mammals are also known to exploit the biota of tidal and other fronts. The localised enrichment at fronts may also affect the benthos. Thus the formation, persistence and location of fronts has important ecological implications the enhanced productivity and concentration of marine life in these areas makes the associated communities particularly vulnerable to exploitation as well as impacts which might be focused in these areas such as pollution incidents which may have a disproportionate impact because of the focus of marine life around fronts. (a) (b) Figure 7 (a) the M 2 tidal amplitude and (b) M 2 tidal ellipses for northern Australia through the application of the ROMS model (courtesy of Matt Rayson and Michael Meuleners, respectively). 27

28 The importance of tidal mixing in the NWS in the generation of the Leeuwin Current was described by Godfrey and Mansbridge (2000). Within the NWS, the shelf waters receive heat from the atmosphere, which, due to tidal mixing, is mixed throughout the water column. This heat flux does not usually penetrate into the deeper water, as it is exported from the shelf via an offshore Ekman transport (Godfrey and Mansbridge, 2000). However, during the autumn months (April, May, June), when the (Australian) monsoon conditions are in transition, the shelf circulation changes, with the additional heat input remaining within the shelf region. Thus the water column warms, which in turn increases the sea surface height. The enhanced sea surface level along the coast results in the generation of a geostrophic southward alongshore current, which, at the southern end of the shelf, reinforces the Leeuwin Current (Godfrey and Mansbridge, 2000) Internal tides Internal tides are generated by the action of tides in the presence of vertical stratification. They are generated at the continental shelf edge and propagate across the continental shelf. There has been considerable amount of work undertaken in the region due to their effects on offshore platforms and sub-sea pipelines (Holloway, 1987, 1994; Smyth and Holloway, 1988; Holloway et al. 1999; Pelinovsky et al, 1995; van Gestel et al., 2009). The waters of the NWS are density stratified particularly in summer due to the intense heating and low precipitation in the region. The region consists of non-uniform bottom topography with a shelf break at 200 m to 400 m depth with relatively deep water further offshore. The tide induces horizontal motion offshore, in turn pushing density stratified water up and across the shelf break and thus generating an internal tide. For example, early observations by Holloway (1983) showed existence of a semidiurnal internal with a wavelength of ~20 km and propagating onshore with a phase velocity of ~ 0.4 ms 1. On the North West Shelf, the tidal ellipses are aligned such that at least part of the tidal oscillation crosses the bathymetry. A variety of internal wave forms have been observed inshore, and the most dramatic features that have been observed are the trains of solitary waves seen in shallow waters and described in series of publications by Holloway (1983, 1987, 1997). Recent field observations on the North West Shelf in 125 m indicated a two layer density stratification with rapid variation in depth of the density contours separating the upper and lower layers, with vertical excursions of contours of O(80 m). These excursions typically consisting of a rapid step like change associated with the passage of a bore-like feature and are followed by a train of solitary waves with decreasing amplitude with successive waves in the train. Being forced by vigorous tides, large amounts of internal wave energy can then propagate into the shallower region. On the North West Shelf, the velocities and turbulent mixing induced by these waves must be known in order to properly design offshore structures. Failure to estimate these effects can have potential serious implications for oil and gas structures and pipelines in the shallower regions, as well as for consequent environmental damage associated with failure and hence spillage Wind driven circulation and upwelling Circulation on the North-west shelf is influenced by the broader scale circulation of the Indonesian Throughflow to the north and Leeuwin Current to the west (see above). These flows transport warmer low salinity water south-west ward along the outer NWS from February to June. However, strong winds from the southwest cause intermittent reversals of these currents over the remainder of the year, with occasional weak upwelling of cold deep water onto the shelf. Wind forced currents only become dominant around the neap tide, when the cross-shelf momentum balance is approximately geostrophic and the dominant subinertial motions are continental shelf waves (Webster, 1985; Holloway and Nye, 1985). Recirculation of ITF waters into the Region via these pathways largely contributes to surface flows off the shelf break, the slope and over the abyss. The origin and movement of shelf waters is not well understood, but it is believed that ITF waters flood the shelf via the offshore pathway (the Eastern Gyral Current) and the Holloway Current. It is also likely that local eddies and internal tides affect cross-shelf transport and modify water properties through vertical mixing. The existence of coastal upwelling along the NWS was first suggested by Schott (1933) and Wyrtki (1962), and Rochford (1977) suggested that upwelling along the NWS was weak. This contrasted with the earlier suggestion (Wyrtki, 1961) that upwelling occurred during the winter months under the action of the southeast trade winds. Holloway and Nye (1985) showed that weak upwelling events occurred, both in the summer and winter months, along the NWS when the currents were flowing north-east and suggested that this north-east flow resulted when the south-west winds were sufficiently strong to overcome the steric height gradient and thus to reverse the dominant south-west flow. These observations reflect the differences in the 28

29 wind regimes along the south and west coasts of Western Australia, where the prevailing summer winds are always upwelling-favourable easterlies along the south coast and southerlies along the west coast. Along the NWS, although upwelling-favourable south-west winds occur, they are not the prevailing winds during either summer or winter. At the time of the upwelling studies, the strong interannual variability in depth of the thermocline associated with El Nino Southern Oscillation was not known. The depth of the thermocline also affects the strength of upwelling and may account for some of the differences in strength noted above. Upwelling needs to be observed as one of the processes that links the physical environment to ecosystems. Ocean colour imagery of the region indicates that during the summer months, when the Leeuwin Current is weakest and upwelling is most likely, phytoplankton biomass on the shelf is much higher compared with deeper waters (Figure 4). The estimated chlorophyll concentrations appear to have strong horizontal gradients and appear to be controlled by the depth contours. It is likely these are location shelf sea fronts. The colour imagery has not been used to our knowledge to study interannual variation of upwelling and links to the internal, physical environment Baroclinic (density driven) circulation The high evaporation along the Pilbara coast and the high freshwater input along the Kimberley coast result in cross-shelf density gradients which are capable of influencing cross-shore exchange. High evaporation together with winter cooling results in higher density water (cooler more saline water) along the coast which results in a high density gravity current along the sea bed this is termed shelf dense water cascade and results in nearshore waters being advected offshore. The dynamics of such flows were documented by Brink et al. (2008) along the Pilbara coast. Along the Kimberley coast, freshwater discharge results in lower density water closer to the coast. This region is defined as ROFI regions of freshwater influence globally and well known similar regions include Liverpool Bay (UK) and the Rhine outflow (Dutch coastline). In ROFI regions the alongshore density gradients together with the tidal action results in a residual circulation similar to that of estuaries where the lower density surface water flows offshore with the higher density water flows onshore near the sea bed (gravitational circulation). Tidal straining may result in the de-stratification during the flood tide which is modulated by the spring-neap cycle. Detailed observations of this complex process will be needed to validate models of the region, particularly as the BLUElink model moves progressively inshore by downscaling. Figure 8 A MODIS satellite image of surface chlorophyll concentration obtained on 29 July 2009 showing the sharp gradients indicative of tidal fronts. 29

30 The Biological Environment Biologically, the nearshore and coastal environments support a diverse array of habitats of high ecological value including coral reefs, seagrass meadows, mangrove forests and sponge gardens. These communities in turn provide critical habitat shelter and food resources for an extremely diverse fish community (Fox and Beckley 2005), especially protected and culturally and commercially important species including marine turtles, cetaceans, dugongs, birds, fishes, and invertebrates. At the broadest level there are two key management issues relevant to the Kimberley: (1) biodiversity conservation and (2) environmental impact assessment (EIA) of development proposals. Controls on Biogeochemistry and Primary Productivity Although detailed biological oceanographic studies off the region along the southern NWS, off North West Cape, have been undertaken by the Australian Institute of Marine Science (AIMS), processes that regulate phytoplankton growth and transfer of productivity to higher trophic levels are relatively unknown in the wider NWS region. The influence of tropical cyclones on the primary productivity was demonstrated by Holloway et al. (1985) and McKinnon et al. (2003). The NWS from North West Cape to Broome is one of the most productive fishing areas in Australia, with extraordinarily high biodiversity, yet the source of nutrients remains poorly explained (Holloway et al., 1985; Tranter & Leech, 1987). It is clear that neither river runoff nor persistent upwelling is the source. The existence of upwelling on the NWS, however, has been under speculation since it was first suggested by Schott (1933). Wyrtki (1962) thought that weak upwelling might occur during the winter months under active SE trade winds and cause nutrient enrichment of the surface water. However, it appears that the source of the nutrients are from the deeper ocean due to episodic events resulting from the Leeuwin Current weakening during El Nino events and cold, nutrient-rich slope waters from the Indian Ocean moving onto the shelf. These waters are then mixed by the strong tides. Thus primary productivity tends to be concentrated below the shallow surface layer, but still within the photic zone, and perhaps supported by nutrients from below (Condie et al., 2003). Brewer et al. (2007) in a review of trophic systems in the North-West shelf marine region concluded that key information gaps exist in the continental slope and shelf break region on the mechanisms, and variability, of nutrient delivery mechanisms onto the continental shelf region. Further, the ecology and connectivity of planktonic larval stages of biota such as fishes remain undescribed for this oceanographically complex region. Benthic ecosystems. Coral reefs in the region fall into two general, though distinct groups the fringing reefs around coastal islands and the mainland shore, and large platform reefs, banks and shelf-edge atolls offshore Seagrasses are biologically important for four reasons: (1) as sources of primary production, (2) as habitat for juvenile and adult fauna such as invertebrates and fish, (3) as a food resource, and (4) for their ability to attenuate water movement (waves and currents) and trap sediment. Distribution and movements of large pelagic species A number of cetacean (whale and dolphin) species are known to occur in the Kimberley region including humpback whales, the snubfin dolphin as well as several other species of delphinid. These species are important because of their iconic status and public appeal and also for their conservation value. Humpback whales are specially protected species in WA due to their threatened status. On the basis of data collected over a 10 year period, there is an important humpback whale calving and resting area between the Lacepede Islands Beagle Bay in the south and Camden Sound in the north. While some cows will calve and rest outside this area, most whales outside the area are migrating animals. The northern migration peaks in July but occurs through July to September. The southern migration peaks for cows with calves at the end of September. Other whale species observed inshore and offshore in the region include pygmy blue whales, false killer whales, pygmy killer whales and blue whales. Six species of marine turtle occur in the Kimberley and all are listed as specially protected species under WA and Commonwealth legislation (Waples 2007). There are coastal beaches and offshore islands in the region that support marine turtle rookeries. Confirmation of this is provided by data from aerial surveys by INPEX covering much of the west Kimberley coast and islands which show some levels of nesting on nearly all islands supporting suitable beach habitat. 30

31 3.4 Science Questions to be addressed by the node A Boundary Currents Factors influencing the Leeuwin Current, where the signal extends from Arafura Sea to Tasmania, in particular: A-1 How does the ENSO signals propagate along the NW, west, and SW coasts of Australia? A-2 What are the relative roles of local and remote forcing driving the seasonal, inter-annual, and decadal variability of the Leeuwin Current and its eddy fields? A-3 What is the role of topography in the generation of Leeuwin Current eddies? A-4 What are the mechanism which the Leeuwin Current and its mesoscale eddies drive the alongshore, cross-shelf exchanges? B Continental shelf processes B-1 the influence of the Indonesian Throughflow (ITF) (i) What is the influence of ITF waters on continental shelf and coastal regions of the Kimberley and Pilbara? B-2 Continental shelf currents (i) Is the Holloway Current a major feature of the regional circulation in north-west Australia and if present, is it driven by alongshore and/or cross-shore pressure gradients?. (ii) What is the northward extent of the Ningaloo Current and the response of the regional currents? (iii) What are main the interactions between Capes and Leeuwin Current? (iv) What is the hydraulic connectivity and variability between the different regions in the northern, north-west and south-west of Australia? B-3 Barotropic dynamics (i) What are the main driving forces (seasonal?) of shelf currents in the region? (ii) What is the relative importance of Coastally Trapped Waves on driving continental shelf circulation? (iii) What is the tidal regime in the region?. In particular, the tides in deeper water in the northern region of Australia B-4 Cross-shelf exchange (i) What is the role of alongshore density gradients generated by (1) freshwater inputs and (2) evaporation in cross shore exchange through baroclinic forcing? (ii) What is the role of wind on cross-shore exchange? B-5 Key processes linking forecasting models for the deep ocean at 10 km resolution (Bluelink) to finer-scale near-shore models. (i) What are the key processes in the region which needs to be included in numerical models? (ii) What data streams are required for model forcing, validation, and assimilation? (iii) How can we facilitate the use of Bluelink and in particular, improve accuracy and resolution? (iv) How can we develop data assimilating hydrodynamic models (ultimately) to as to extrapolate observations and improve observing system design? 31

32 C Biological response C-1 Large-scale ocean drivers of variability of water quality (temperature salinity, turbidity, chlorophyll, primary productivity). (i) What is the natural variability of water quality (particularly under water light, TSS, temperature, Chlorophyll, primary productivity) in the region? (ii) What is the influence of water quality on ecosystems? (iii) What are the dynamics of regional nutrient supply associated with production? C-2 Effects of tidal and wave dynamics on marine habitats. (i) What is the role of tidal fronts in controlling the biological productivity? (ii) What is the role of internal waves on biological productivity? (iii) What is the influence of tidal and wave stress on bottom habitats? C-3 Water column processes. (i) What are the mechanisms of alongshore and cross-shelf dispersals of fish larvae and other biota? (ii) What is the nature and variability of planktonic ecosystems supported by cross-shelf exchange C-4 Natural variability of populations and pathways of large marine fauna. (i) What are the migration pathways of mega-fauna in the region? (ii) Can seasonal patterns of use be determined, or precisely when are they present and what controls this? (iii) How can we monitor over the long term, trends in mega-fauna populations and link these to physical factors? (iv) How can we use marine vertebrates as platforms to collect oceanographic data? 3.5. How will the node activities fit within a national IMOS? The proposed observation system has been designed to monitor the the Leeuwin Current and its influence on the continental shelf environments, ecosystems and biodiversity as stated in the IMOS strategic goals. As described in section 1, the Leeuwin current is the major boundary current in Australia influencing almost 2/3 of the continents shelf and slope water extending from Arafura Sea to Tasmania (Figure 1). This proposal has a very strong integration component with the Bluewater and Climate, South Australia and Tasmanian nodes of IMOS. This integrated approach is reflected in the latitudinal sequence of monitoring locations along the path of the Leeuwin Current as proposed by each of the respective nodes. Bluewater and Climate provides the signal from the Indonesian Through Flow, WAIMOS provides information from the LC along the NW and W coasts of Australia inputting into the South Australia and Tasmania nodes. 4. Pre-existing observations: 4.1: Non-IMOS: National/State wide networks Surface Meterorological Data (Bureau of Meteorology): ( Sea level Data (Department of Planning and infrastructure, WA and National Tidal centre) ( 32

33 Wave data (Department of Planning and Infrastructure, WA) ( The above data have records of ranging from 15 (waves) to over 100 years (sea level at Fremantle) North-west Australian waters In addition to above there has been a large number of physical oceanographic observations (mainly of timeseries of currents, temperature and waves) undertaken throughout the region by resource companies, particularly by Woodside Energy Ltd. These observations have generally being of 1-2 year duration and located in regions of interest to the resource companies. A long-term (> 12 year) time series of currents and temperature has been collected from the vicinity of North Rankin A platform by Woodside Energy. In general, these data sets are not available to researchers except through agreement with the resource company South-west Australian waters Pre-IMOS, in addition to the National/State wide networks above, Rottnest Island Coast station provides a 60 continuous data set off the southwest coast of WA. All these observations are clustered around the Perth metropolitan region (Figure 16). Figure 16: Locations of Pre-IMOS and on-going data available near the Perth metropolitan region. Many are available in near-real time. Over the past 20 years there also has been extensive CTD, current meter and biological data which have been collected as part of either major multi-disciplinary programs; National Research Facility Vessel voyages; and, individual research projects (including PhD projects). These include: Leeuwin Current Interdisciplinary Experiment, LUCIE ( ) Perth Coastal Water Study funded by Water Authority of WA ( ) Southern Metropolitan Coastal Water Study funded by EPA ( ) Perth Long term Ocean Outfall Monitoring Study Strategic Research Fund for the Marine Environment (SRFME) Two Rocks transect ( ) Southern Surveyor voyages in 2003, 2004, 2006 and WAXA pigmy blue whale project funded by Royal Australian Navy PhD projects: Majid Alaee (Rottnest Island wake, UWA); Nasser Zaker (Whitfords lagoon, UWA); Susan Rennie (Perth canyon, Curtin/UWA); Barbara Muhling (ichytoplankton off Two Rocks, Murdoch); David Holliday (fish larvae in Leeuwin Current eddies, Murdoch); Cecile Rousseaux, Saskia Hinrichs (Ningaloo Reef, UWA); Thisara Welhena (Rottnest Shelf, UWA) Western Australia Marine Science Institution surveys in Perth/Marmion region, Esperance/Albany, and Ningaloo during

34 A number of instrument systems have been allocated to west and southwest Western Australia under the NCRIS funds both in the coastal and offshore waters. In the following sections the various data streams available from the south-west Australian waters are summarised. 4.2 IMOS Observations A number of instrument systems have been allocated to west and southwest Western Australia under the NCRIS funds both in the coastal and offshore waters. In the following sections the various data streams available from the south-west Australian waters are summarised HF radar (Australian Coastal Ocean Radar Network, ACORN) WAIMOS has installed two types of HF radars: CODAR Ocean Sensors SeaSonde and a high resolution WERA radar. The CODAR ( SeaSonde long range monitors currents up to 150 km from shore during daytime, less during night time when environmental noise levels increase, providing 6 km resolution surface velocity maps at hourly intervals. The WERA system will provide, in addition to surface currents, surface wave information (wave height, period and direction) and the wind direction at hourly intervals (wave direction at 3 hourly intervals). The coverage of the WAIMOS radar systems are given in Figure 17. The purple region will be covered by the CODAR data with stations at Seabird and Cervantes. The second HF Radar system WERA will have stations at Guilderton and Leighton Beach and will cover the region outlined in green. The CODAR Seasonde stations were installed by the ACORN Facility at Cervantes and Seabird and started operating at the end of March The WERA systems have been delivered but there has been a delay in grant of planning permission by the Fremantle Council for the shore station at Leighton Beach, so it is expected that this system will become operational in late Currently, routine data collection from both the CODAR and WERA systems are planned to start by December 2009 as provided by ACORN. Initial data plot of currents measured by the SeaSonde stations clearly identifies the Leeuwin Current signature flowing southwards at surface speeds over 0.60 ms -1 (Figure 18) Figure 17: Schematic of the 2 long range radar shore stations and WERA medium range radar and their expected coverage. 34

35 Figure 18: Example data from the SeaSonde stations at Cervantes and Seabird showing the Leeuwin Current Shelf moorings (Australian National Mooring Network, ANMN) Five shelf moorings off Two Rocks were deployed in July 2009 and the first recovery is planned in December 2009 (Figures 19 and 20). The moorings consist of a combination of thermistor strings, ADCP current measurements and water quality parameters. There has been some delay in deploying the moorings in the Perth Canyon due to weather conditions and these moorings are planned to be deployed late this year after CSIRO recruits technicians based in Floreat, WA. Figure 19: NCRIS funded shelf mooring arrays off Two Rocks and in Perth Canyon. The red dots denote the thermistor moorings, black dots denote thermistor/bgc/adcp moorings, and the green dot denote thermistor/adcp mooring. The co-located Rottnest NRS (yellow dot) and AATAMS moorings (squares) are also shown. The Slocum gliders (to 200m) will be released at Two Rocks and will undertake transects across the shelf and returning through the Perth Canyon). Note glider tracks are indicative and dependent on the local conditions at the time of deployment. 35

36 Figure 20: Instrumentation of the Two Rocks mooring array Passive Acoustic Observatory (ANMN) Three acoustic noise loggers have been deployed in the Perth Canyon (Figure 19) since February 2009 and began to collect data in non real time. The stations will provide baseline data on ambient oceanic noise, detection of fish and mammal vocalizations linked to ocean productivity and whale migration patterns and detection of underwater events National reference stations (ANMN) In IMOS, three of the nine NRS stations are being established in Western Australia: Ningaloo reef, Rottnest Island and Esperance (Figure 21). The Rottnest Island NRS station continues the CSIRO Rottnest station which has been collecting temperature and salinity data over a period of several decades, and the Ningaloo NRS station has been selected to be close to the AIMS ADCP mooring which has been collecting velocity profile for the last decade. The Rottnest and Esperance NRS stations have been implemented by the CSIRO ANMN team. Each station has a mooring deployed at about 50 m water depth, with 2 WQM and 2 thermistor sensors to measure conductivity, temperature, depth, dissolved oxygen, photosynthetically available radiation (PAR), fluorescence and turbidity. The moorings are being serviced every 3 months. As an example time series of temperature, salinity and chlorophyll (fluorescence) during one deployment from the Rottnest NRS station is shown in Figure 22. Full physical sampling have also started at the two NRS stations, with a monthly sampling rate for Rottnest and quarterly sampling rate for Esperance. The physical samples will be analysed for nutrients and plankton species (both visibly and genetically). The Ningaloo NRS Station will be established in early

37 Figure 21 Location of National Reference Stations in Western Australia Figure 22: Time series of temperature, salinity and chlorophyll fluorescence from the Rottnest Island National reference station for the period 20 Nov 2008 to 18 Feb

38 4.2.5 Ocean gliders (Australian National Facility for Ocean Gliders, ANFOG) For WAIMOS, two different types of gliders are proposed. The Slocum glider is designed to operate to a maximum depth of 200m and a maximum endurance of 30 days, whilst the Seaglider is able to operate to a maximum depth of 1000m and a maximum endurance time of up to 6 months. Both gliders will have the same suite of sensors to measure conductivity (for salinity), temperature, dissolved oxygen, fluorescence, turbidity and CDOM (dissolved organic matter) with depth. The Slocum shelf gliders were deployed almost continuous along the Two Rocks transect since January 2009 (Figure 23). A summary of deployments are presented on Table 1 and tracks in Figure 20. During the period January to June 2009, the Slocum gliders travelled almost 3000km and performed over vertical dives (casts). Table 1 Slocum glider deployments along the Two Rocks transect Glider Project Deployed Recovered Distance Duration Casts unit130 WAIMOS 03 Jun 2009 on going 315 km* 15 days* 2293* unit109 WAIMOS 15 May Jun km 19 days 4300 unit104 WAIMOS 02 Apr Apr km 25 days 3939 unit104 WAIMOS 13 Mar Mar km 14 days 2232 unit106 WAIMOS 20 Feb Mar km 21 days 3225 unit106 WAIMOS 20 Jan Feb km 21 days 2937 unit104 WAIMOS 21 Jun /07/ km 14 days 3350 As an example, salinity data collected along the Two Rocks repeatedly between 24 January and 20 April 2009 are shown on Figure 23. The region of glider deployments experiences a Mediterranean climate with hot summers and cold winters. During the summer months the inner continental shelf waters increases in salinity due to evaporation. This results higher density water closer to the shore when compared to offshore waters and a gravitational circulation is set-up where the inner shelf water are transported as higher salinity plumes into deeper waters (Figure 23). Previous data indicated that this is mainly a winter phenomena however, glider transects shown on Figure 23 indicates that the higher salinity plumes are set-up in summer (February) and continues into the winter months (June). The Seaglider will be deployed offshore Dampier and then recovered off Rottnest Island (Figure 24). As the Seaglider has a 6 month endurance, it will be able to do many cross-shore transects - but it will be dependent on the strength of the Leeuwin Current, presence of eddies etc. It is possible, depending on the availability of gliders to release gliders at 3 monthly intervals (e.g. release one and 3 months later release the next one), resulting in two Seagliders in the water - so that we get 3 monthly transects. 38

39 Figure 23: Slocum glider tracks along the Two Rocks transects over the period January to June

40 (a) (b) (c) (d) (e) (f) Figure 24: Slocum glider tracks showing the salinity variation along the Two Rocks transects over the period January to April (a) 24/01/09; (b) 22/02/09; (c) 14/03/09; (d) 21/03/09; (e) 10/04/09; (f) 20/04/09\ 40

41 Figure 25: Proposed Seaglider glider tracks. The Seagliders (to 1000m) will be released at Dampier and recovered off Rottnest Island. Note glider tracks are indicative and dependent on the local conditions at the time of deployment Ningaloo Reef ecosystem tracking array (Australian Acoustic Tracking and Monitoring System, AATAMS) Acoustic monitoring is a powerful tool for observing animals in coastal and continental shelf ecosystems with networks of receivers, allowing animals to be monitored over scales of 100s of metres to 100s of kilometres. Tracking animals using these tags has been invaluable for monitoring habitat use, home range size, timing of long term movements, migratory patterns, etc. as well as examining biotic and abiotic factors in animal distribution and movements. A permanent acoustic array is being established on Ningaloo Reef the Ningaloo Reef Ecosystem Tracking Array (NRETA). Ningaloo Reef within the Ningaloo Marine Park in Western Australia abuts the narrowest part of Australia s continental shelf. In this relatively small area there are a variety of habitats with high biodiversity, and the reef experiences seasonal pulses of productivity. It is also a region free from commercial trawling. There are a number of very pressing ecological questions in relation to the Ningaloo Marine Park regarding: assessing the effectiveness of recently created MPA s as a refuge for commercial species, ecotourism with iconic megafauna, and a need to increase knowledge of trophic linkages and key top predators in this ecosystem. Ninety-six receivers have been deployed as three arrays and three lines: 50 receivers in Mangrove Bay (to track reef fishes, reef sharks, and rays); 8 receivers off Skeleton Beach (to track reef sharks); 10 receivers in Stanley Pool (to track mantra rays); 7 receivers along the north line; 13 receivers along the central line; and 12 receivers along the south line. Marine animals tagged include 103 reef fishes and 80 sharks and rays. A report on the status of the Ningaloo Reef ecosystem tracking array has been submitted to the WA Department of Environment and Conservation. 41

42 Figure 26: Map of Mangrove Bay receiver array (red waypoints) and movements of a single tagged Spangled Emperor over a 12 month period (pink line). The individual remained in nearshore homerange habitat for most of the year, apart from an excursion to a spawning area outside the reef. Several other tagged fish also displayed this type of behaviour Proportion < >10 50% kernel area (km2) Figure 27:. Cumulative proportion of 50% kernel area for 40 L. nebulosus. For those animals that moved outside of the array, the area was assumed to be greater than 10 km Rottnest Island Ferry temperature data (Ships of Opportunity, SOOP) Sea surface temperature sensors together with data modems will be established on a Rottnest Island ferry to provide real-time data between Fremantle and Rottnest Island Available Data Streams (emarine Information Infrastructure, emii) The following data streams are currently available on-line through emii: National Reference Station time series from Rottnest and Esperance Slocum Ocean Glider transects along Two Rocks transect Rottnest Ferry temperature data AATAMS moorings in Ningaloo and along the south coast of WA 42

43 5. What observations does the Node require during , and how will they address the research questions? 5.1. Observations required by the node; 5.1. Northern Australian Waters Figure 28: Proposed infrastructure in Northern Australia Mooring lines: The mooring lines have been selected so that they cover the different regions of northern Australia (Table 1) and their requirements to address the science challengers (section 3.1.3) and as an overall integrative component of monitoring the Leeuwin Current signal from Arafura Sea to Tasmania (Figure 1). Arafura-Wessels Pair Two fixed moorings are located in the Arafura sea to define the seasonal cycle of the Leeuwin current signal. each mooring will consist of a bottom mounted ADCP, 10 thermistor string, surface and bottom CTD, WQM, pressure sensor, PAR. ITF line Here, WAIMOS will instrument the Australian North West Shelf (3 moorings), the Bluewater and Climate Node will instrument Timor and Ombai Passages, while the remaining major passages will be instrumented by US NOAA and Korea s KORDI (Lombok, Makassar, Lifamatola). Fixed moorings along the continental shelf, each consisting of bottom mounted ADCP, 10 thermistor string, surface and bottom CTD, WQM, pressure sensor, PAR. Kimberley line: fixed moorings along the continental shelf. The first 3 is located along the continental shelf whilst the deepest at 1000m is along the continental slope. The moorings will consist of bottom mounted ADCP (in the upward and downward looking ADCP s will be mounted at ~200m depth to cover the entire water column) 10 thermistor string, surface and bottom CTD, WQM, pressure sensor, PAR. The deepest station will include passive acoustic receivers. The fixed moorings will be complemented by quarterly Slocum glider tracks Surface temperature/salinity data obtained through the mounting of a ferry box on a supply vessel. 43

44 Surface drifter releases using the supply vessel. Pilbara line fixed moorings along the continental shelf, each consisting of bottom mounted ADCP, 10 thermistor string, surface and bottom CTD, WQM, pressure sensor, PAR. The deepest station will include passive acoustic receivers. The fixed moorings will be complemented by quarterly Slocum glider tracks Surface temperature/salinity data obtained through the mounting of a ferry box on a supply vessel. AUV transects off northern Australia It is planned to undertake a number of repeated transects in Ningaloo reef and Scott Reef to: Sustained quantified measures to link density and distribution of key sessile benthos particularly reef building scleractinian corals, Halimeda, and filter-feeding communities (sponges and soft corals), Measure and monitor reef acidity over environmental gradients found on these benthic systems. Monitoring of metapopulation level data (size frequency distribution info) and measurement of drivers for key benthic groups over environmental gradients (including estimates of recruitment) Monitoring of fine and broader scale three dimensional reef structure and biomass of sessile primary producers. Monitor the presence of coral disease and sponge disease, which are increasing in frequency globally, in deeper water habitats. Broad transects will be used to monitor broad community structure and integrity, community boundaries and transitions Dense grids (Figure 28 b) are designed to i) collect meta-population measures for major benthic communities (Figure 28 c-e) ii)estimate changes in three dimensional reef structure and ii) Estimate change in biomass of sessile benthic primary producers iii) Detect and monitor any signs of coral disease Fine scale full cover grids (Figure 28 f-g) will be used to i) facility highly accurate fine scale monitoring of reef structure ii) estimate recruitment of corals and sponge groups iii) monitor boundaries between major sessile benthic groups. 44

45 Figure 28. Proposed cross-shelf benthic survey sites at Ningaloo Marine Park, Western Australia. These sites contain contrasting benthic communities set within differing shelf width contexts adjacent to the Ningaloo Reef. 45

46 Figure 29 - (a) Scott Reef AUV dive tracks overlaid on the bathymetry. The dive profiles are coloured by inferring depth of seafloor to illustrate the extent of coverage and design of survey profiles. (b) Details of grid survey overlain on the detailed bathymetry. This method was targets a particular seafloor reef feature located near the centre of the lagoon. (c)-(e) Examples of the imagery collected from this illustrating the variety of coral communities imaged by the vehicle. (f) Reconstruction of seafloor at the edge of a coral reef community. The site was targeted as the interface between reef and sandy habitats. Revisiting sites such as these will allow monitor rates of change and turnover in these environments (g) Fine scale multibeam bathymetry collected by the AUV in the sampling method multibeam data is gridded at 10 cm resolution. 46