Duffins Creek State of the Watershed Report
Aquatic Habitat and Species June 2002 Other topics in this series for both the Duffins Creek and the Carruthers Creek include: Introduction Study Area Human Heritage Greenspace, Trails and Recreation Land Use Air Quality Climate Surface Water Quality Surface Water Quantity Stormwater Management Fluvial Geomorphology Hydrogeology Terrestrial Natural Heritage Cover image: Rainbow trout. Image credit: Bowen, Rae This document is intended to be shared for non-commercial use. We are promoting the electronic use of this document to minimize the consumption of paper resources. Toronto and Region Conservation, 5 Shoreham Drive, Downsview, Ontario M3N 1S4 Telephone: (416) 661-6600 Fax: (416) 661-6898 www.trca.on.ca
Table of Contents Introduction to Aquatic Habitat and Species....................2 Riverine Habitat..............................................3 Lacustrine Habitat...........................................10 Estuarine Habitat............................................10 Data Gaps..................................................11 Summary...................................................12 References..................................................13 Tables and Figures Table 1: Duffins Creek Cumulative Species List............................................5 Table 2: Duffins Creek Estuarine Marsh Cumulative Species List...............................11 Figure 1: An Index of Biological Integrity (IBI).............................................7 Figure 2: The 2000 Survey of 32 Sites in the Duffins.........................................9 1
Introduction to Aquatic Habitat and Species The health of the aquatic environment and the condition of the Duffins Creek watershed are interconnected. This is because the aquatic environment is directly affected by the quality and quantity of water that flows over or through the land. The health of the aquatic habitat, therefore, is an indicator of the health of the watershed. The aquatic ecosystem is most often described as fish habitat since fish communities are important resources, and as such, have a long history of being used as indicators of aquatic ecosystem health. Aquatic habitat is an integral part of the watershed s ecosystem as it provides feeding, breeding and rearing areas for resident and migratory fish and invertebrate species. Within the watershed, aquatic habitats can be divided into several different habitat categories, on the basis of suitability for differentiating aquatic communities. These habitat categories fall into three broad groups: riverine habitat (creeks and rivers), lacustrine habitat (ponds and lakes) and estuarine habitat (coastal marsh). In the following sections each habitat category is identified and its significance, condition and any changes in condition over time are described. In 2000, a survey of fish communities and habitat was conducted to provide a benchmark of our current knowledge of the watershed, allowing for the identification of significant management issues as well as gaps in our knowledge. A comprehensive analysis of the fish community, aquatic habitat and a management plan for the aquatic ecosystem will be completed early in 2002. 2
Riverine Habitat Riverine habitat is found in rivers and creeks and can be divided into coldwater and warmwater habitat categories. The determinants of which type of habitat exists in a particular location is a result of a number of watershed and more local level characteristics that affect fundamental components of the habitat such as flow regime and water temperature. The underlying geology, in conjunction with riparian vegetation (i.e. vegetation adjacent to streams) and land use, produce the flow, water temperature, water quality and associated aquatic community that we see today. To understand the current health of fish communities and their potential, it is necessary to interpret these communities in the context of these three factors. Duffins Creek begins on the extensive sand and gravel deposits of the Oak Ridges Moraine, which forms the height of land in the northern part of the watershed. To the south, the river crosses the silt and clay till plains of glacial Lake Markham and the slightly sandier Halton Till. Even farther downstream, the creek crosses the sands and gravels of the Lake Iroquois Shoreline and then the silt and clay deposits of the old lake bed. Below the deposits at the surface, the geology alternates between the layers of lacustrine silt and clay and fluvial deposits (i.e. associated with streams or rivers) of sand and gravel. Many of these deeper deposits reach the surface within the deep valleys in the lower part of the watershed. Each of the geologic deposits the creek drains from or crosses, influences the characteristics of the creek and thus the conditions that support the aquatic communities. For further details refer to the Hydrogeology chapter in this series. The principal way in which the geology of the watershed influences the fish community is by moderating flow and water temperature. The coarse surficial deposits encourage infiltration of surface water across the landscape on which they occur and thus reduce overland surface flows to local streams. As a result, streams draining from areas with coarse soils such as the Oak Ridges Moraine or the Iroquois Shoreline tend to have less frequent storm flow conditions and a significant baseflow component due to groundwater discharge. This combination results in an overall more stable flow regime, which is characteristic of streams in the Duffins Creek watershed. Groundwater, a characteristic related to geology, is another important factor that determines the type of habitat and associated fish community that can be sustained. Groundwater seeps or flows into the creek where the aquifers (the subsurface water-bearing deposits) are exposed. The more groundwater discharge into the watercourse, the greater the potential for coldwater habitat. At 8-10 C year round, groundwater is the source of cold water to watercourses. The addition of warm flow from parking lots or streets moderates the cold water and reduces the area of coldwater habitat. A good way to understand and measure whether groundwater inputs are significant for aquatic habitat is to examine the ratio of baseflow, a measure of groundwater input, relative to the annual flow. Research indicates that a ratio of greater than 20 per cent groundwater discharge to average annual flow is required to support trout species. This occurs when roughly 20 per cent of the total average annual flow is derived from groundwater discharge into the creek. Current estimates of base flows in the watershed range from 50 per cent for Duffins Creek south of Highway 2, to 37 per cent for the West Duffins at Green River, 61 per cent for the East Duffins above Pickering, and up to 50-60 per cent for Ganatsekiagon Creek and Urfe Creek (Eyles et al., 1997; Sibul et al., 1977). Currently, Duffins Creek contains 380 kilometres of watercourses. They are in relatively good condition and are dominated by cold water aquatic communities that include sculpin, trout and numerous other fish species. Based on the database of fish collections at the Royal Ontario Museum s Ichthyology Department, there have been 45 riverine species of fish found in the 3
4 Duffins watershed (Table 1). Included in this list are nine non-native species: sea lamprey, rainbow trout, brown trout, coho salmon, chinook salmon, alewife, goldfish, white perch and common carp. Although non-native, the trout and salmon species are considered by some to be desirable from a recreation standpoint. At one time trout and salmon were stocked in the creek; presently only brown trout are still being stocked. Atlantic salmon is the only known extirpated species once found in Duffins Creek (ODPD, 1956). The creek is currently being used by the Ministry of Natural Resources to research the habitat requirements and to evaluate the feasibility of restoring Atlantic salmon to Lake Ontario tributaries. In the 2000 survey of the Duffins fish community, 28 species were encountered (Table 1). This included three non-native species: chinook salmon, rainbow trout and brown trout. The fewer species found in the 2000 survey is likely a reflection of the decreased extent of sampling, the sites selected for sampling and possibly some species losses. Coldwater streams in the upper and middle reaches of the Duffins Creek watershed provide habitat for species such as brook trout, and slimy and mottled sculpin. They also provide habitat for species at risk such as redside dace (Clinostomus elongatus). In the lower reaches of the west and east Duffins Creek there is coldwater habitat that supports a healthy, self-sustaining, rainbow trout population. It is also likely that chinook and coho salmon spawn successfully in the lower reaches. These species of salmon and trout are separated from the native brook trout populations by several instream barriers that prevent the upstream movement of migratory species. Previous studies have shown that the non-native salmon and trout would out-compete the native brook trout if their distributions were allowed to overlap. According to the MNR District Fisheries Management Plan 1989-2000, the Duffins Creek watershed supports primarily brook and brown trout in the headwaters and migratory salmonids below Highway 7. Most of the watershed is considered coldwater habitat with the exception of Stouffville Creek, and the lower Duffins below Highway 401. Stouffville Creek once was coldwater habitat, but now it is warmwater because of the presence of the Stouffville reservoir, an online pond, and a lack of woody riparian vegetation to shade the stream. Conversely, the lower Duffins Creek is a natural warmwater reach. This a consequence of the size of the creek and the low quantities of groundwater input into the creek at this location in the watershed. The lower Duffins and associated marsh provide good habitat for a number of warmwater species such as smallmouth bass, northern pike and pumpkinseed. The ecological health of a fish community can be quantified through the calculation of an index of biological integrity (IBI). The IBI figures quantifies the health of the fish community by incorporating species richness, trophic balance, the abundance of fish, and the presence of indicator species into one index. This method was first proposed by Karr (1981) and was further modified and calibrated for southern Ontario streams by Steedman (1988). Interestingly, fisheries information from the Duffins watershed was used by Steedman to calibrate the IBI for southern Ontario streams. More importantly, he found that many (77 per cent) locations in the watershed had good to excellent fish communities (Figure 1). Surveys from the 1990s found similar conditions, which is expected, because there have been few changes in the watershed that would impact the fish community. Overall, analysis of the watershed from the 1950s to the 1990s has demonstrated a general increase in the number of species and the distribution of trout species (Jones and Guy, 1997). The 2000 survey of 32 sites in the Duffins resulted in IBI scores from fair to excellent, with a median score of good (Figure 2). This is a good result given that a high percentage of the sites scored good (53 per cent), three were excellent (9 per cent) and no sites were in poor condition or had no fish present (Figure 2).
Table 1: Duffins Creek Cumulative Species List COMMON NAME SCIENTIFIC NAME PRESENT IN 2000 SURVEY LAMPREY FAMILY American brook lamprey Lampetra appendix ü northern brook lamprey 5 Ichthyomyzon fossor ü sea lamprey 1, 4 Petromyzon marinus SALMON FAMILY chinook salmon 1 Oncorhynchus tshawytscha ü coho salmon 1 Oncorhynchus kisutch rainbow trout 1 Oncorhynchus mykiss ü Atlantic salmon 3 Salmo salar brown trout 6 Salmo trutta ü brook trout Salvelinus fontinalis ü SUCKER FAMILY white sucker Catostomus commersoni ü northern hog sucker Hypentelium nigricans MINNOW FAMILY goldfish 2 Carassius auratus northern redbelly dace Phoxinus eos ü finescale dace Phoxinus neogaeus redside dace 5 Clinostomus elongatus common carp 2 Cyprinus carpio brassy minnow Hybognathus hankinsoni hornyhead chub Nocomis biguttatus river chub Nocomis micropogon common shiner Notropis cornutus ü spotfin shiner Cyprinella spilopterus ü sand shiner Notropis stramineus common shiner x Luxilus cornutus x creek chub Semotilus atromaculatus ü bluntnose minnow Pimephales notatus ü fathead minnow Pimephales promelas ü blacknose dace Rhinichthys atratulus ü longnose dace Rhinichthys cataractae ü creek chub Semotilus atromaculatus ü pearl dace Margariscus margarita central stoneroller Campostoma anomalum Continues on page six. 5
Table 1: Continued from page five COMMON NAME SCIENTIFIC NAME PRESENT IN 2000 SURVEY CATFISH FAMILY yellow bullhead Ameiurus natalis brown bullhead Ictalurus nebulosus ü channel catfish 4 Ictalurus punctatus stonecat Noturus flavus FRESHWATER EEL FAMILY American eel 4 Anguilla rostra STICKLEBACK FAMILY brook stickleback Culea inconstans ü three-spine stickleback Gosterosteus aculeatus TEMPERATE BASS FAMILY white perch 1, 2 Morone americana SUNFISH FAMILY rock bass Ambloplites rupestris ü pumpkinseed Lepomis gibbosus ü smallmouth bass Micropterus dolomieui ü largemouth bass Micropterus salmoides ü PERCH FAMILY yellow perch Perca flavescens rainbow darter Etheostoma caeruleum ü Iowa darter Etheostoma exile ü johnny darter Etheostoma nigrum ü logperch 4 Percina caproides ü least darter Etheostoma microperca SCULPIN FAMILY mottled sculpin Cottus bairdi ü slimy sculpin Cottus cognatus ü 1 introduced species; 2 naturalized species; 3 extirpated species; 4 found only in estuarine habitat; 5 Species at Risk, classified as special concern COSEWIC; 6 resident brown trout are naturalized while migratory brown trout are introduced. 6 Invertebrate samples are also used to assess habitat condition and water quality because they are a food source for many fish species and respond quickly to environmental perturbations. In general, mayflies (Ephemeroptera) and stoneflies (Plecoptera) are considered the most sensitive benthic taxa because they depend on clean and well-oxygenated water. An overview of the invertebrate communities in the Seaton lands (Ganatsekiagon, Urfe, Whitevale and West Duffins creeks) found that most sampling stations were characterized as having a high proportion of pollution-sensitive species (HBT AGRA, 1994). The only sites where pollution-tolerant groups were
Figure 1: An index of biological integrity (IBI), figures quantifies the health of the fish community by incorporating species richness, trophic balance and the abundance of fish, and the presence of indicator species. Data from Steedman s 1988 study. 7
8 found were in West Duffins Creek at the Brock landfill and at Whitevale, yet in these samples there were still many pollution-sensitive species. Recent studies from headwater areas in the West Duffins and East Duffins subwatersheds similarly found high proportion of sensitive species (TRCA, 1999). These results are a strong indicator that Duffins Creek has a healthy invertebrate community. The Duffins Creek watershed has experienced a number of changes over the years. Historically the watershed was dominated by vast forests that had a tremendous influence on the hydrology of the watershed. With settlement came deforestation and a variety of agricultural practices that impacted the system but, due in part to the large amounts of groundwater discharging to the stream, the sensitive species such as brook trout were not lost. Other changes, such as transportation, urbanization, water taking, barriers and ponds, have impacted the watershed, however, their extent within the watershed is limited and as such the impact to aquatic habitat and species has not been substantive. In the past 50 or so years the condition within some areas of the watershed has been improving. For example, in some of the headwater areas where the glacial soils are poor for agriculture and in the provincial Seaton and federal airport lands, there has been significant amounts of regeneration of table land and riparian forests. This increase in forest cover has led to a reduction in surface flows and a stabilization of the overall flow regime, better aquatic habitat and an overall improvement in the condition of some fish communities. In fact, the fish community in the West Duffins Creek has improved since the 1950s. In the 1950s first extensive fish survey of the Duffins Creek watershed, sensitive species such as brook trout and sculpin were largely restricted to the headwater areas. Since the 1950s the conditions have improved and these species have extended their range to other areas (Jones and Guy, 1997). With many areas still requiring woody riparian vegetation, there is room for further improvements in the fish community and the aquatic system in general. Improvements have not occurred with respect to the mitigation or removal of in-stream barriers. Structures that act as barriers include dams, weirs, level crossings and some culverts. Many of the large structures were created historically to produce power for grist or saw mills. In more recent years they were built to create recreational ponds. Other barriers may include structures that increase water velocities. These velocity barriers may be created through incorrectly sized culverts that increase water velocities to the point where they do not allow for fish passage. Generally these structures serve as barriers to migratory fish movement upstream and may bar fish access to important spawning or rearing areas. Barriers also fragment resident fish populations by limiting their movement within the watershed. The presence of barriers in the watershed can have a positive or negative effect. In the Duffins, some of these barriers are helping to protect native brook trout populations from migratory salmonids or prevent sea lamprey from accessing potential areas. Other barriers fragment brook trout habitat, limiting access to summer refugia or fall spawning habitat. Managing the effects of instream barriers is an important issue that must be addressed in the development of a watershed fisheries management plan. Future land use activities and developments within the watershed should address the decreased ability of urbanized areas to infiltrate water and their ability to speed up the movement of water towards the creek. These alter the hydrologic cycle toward less groundwater infiltration and greater surface runoff. If the changes in the surface and groundwater regimes are large enough, they can significantly impact both coldwater and warmwater habitat, making preservation of the current regime important.
Figure 2: The 2000 survey of 32 sites in the Duffins resulted in IBI scores from fair to excellent, with a median score of good. 9
10 Lacustrine Habitat Lacustrine habitat is characterized by the presence of standing water. Two types of lacustrine habitat found in the Duffins Creek watershed are online and offline ponds and lakes. In total, these ponds and lakes cover an area of more than 2.5 km 2 in the watershed. There are approximately 172 online ponds in the watershed averaging 0.5 ha in size. These ponds are directly connected to the creek with the creek passing directly through the waterbody. Offline ponds may be completely isolated from the creek with little or no connection, or indirectly connected through a pipe that directs some flow from the creek to the pond. There are approximately 746 offline ponds in the watershed. Ponds can also be created through a variety of acts of nature. Many ponds are created as a result of beaver building dams with wood and other debris. These structures are generally not a concern as they are natural and tend to be transient in nature. Ponds may also be formed through the normal migration of the creek, which can create oxbow lakes or ponds. Kettle lakes were also formed by nature through the melting of trapped ice on the Oak Ridges Moraine during the last ice age. Kettle lakes are common in the headwater areas, with the greatest density found in the Township of Uxbridge. There are a large number of human-made ponds in the watershed that were created to power mills, water livestock or to provide aesthetic or recreational values. Many of these and other ponds are capable of supporting small populations of brook trout. Some ponds were created to enhance brook trout populations. One such pond is the 8 ha Secord Pond located in the upper west Duffins Creek southeast of Goodwood. Although there was recreational benefit from the creation of this pond, it also prevented trout from accessing spawning habitat on significant groundwater discharge zones upstream/downstream of the pond. Most of the kettle lakes and ponds in the watershed are much smaller and support correspondingly smaller fish and fish communities. Online ponds are depositional areas that accumulate sediments and tend to evolve into wetlands and eventually uplands over time. The accumulated sediments can pose a risk to downstream fish communities if released from the pond or reservoir. Online ponds may also contribute to warming of the creek because large ponds and lakes, such as the Stouffville Reservoir, slow the water and allow the surface temperatures to rise. This results in increased temperatures downstream and may make the habitat less suitable for coldwater species. In some cases this warming effect can be mitigated if the water is released from the bottom of the pond where it is usually cooler. Estuarine Habitat The coastal marsh located at the confluence of Duffins Creek and Lake Ontario covers 41 ha. This area is of critical importance to many fish species. A total of 27 species have been recorded from the marsh area (Table 2). Species found here include creek species, but also typically lake resident species such as northern pike, yellow perch, gizzard shad, alewife, white bass and white perch. Of importance is that the area provides spawning and rearing habitat for 18 of these species. In total, 81 per cent of the 27 species found in the marsh area use it for either spawning or rearing purposes (Stephenson, 1988). Four species found in the marsh the common carp, alewife, rainbow trout and white perch are introduced species. This area is designated as an environmentally significant area (ESA), an area of natural and scientific interest (ANSI), as well as a provincially significant wetland because of its importance to fish, plants and other wildlife species. There are several attributes that make the marsh an important area for fish. First, this area serves as a transition zone between the creek and lake. The
marsh is affected by changes in the watershed as well as the water levels that occur in the lake. This transition provides ideal spawning and rearing conditions. Second, the marsh is a very productive area. This occurs because of the low gradient that serves as a depositional area for upstream sediments. The low gradient in this part of the watershed and sediments create a wide flood plain that is seasonally inundated with water. The sediments also provide nutrients to the system, while the nutrients support a dense weed growth that provide excellent cover for growing fish and also provide a resource base/ food source for the growing fish and prey. These estuarine marshes are under threat throughout the Great Lakes region (Stephenson, 1988). Given the marsh s importance to the fish population in the creek as well as to lake fish species, it is of critical importance to protect this area. Data gaps One non-specific management concern is to fill data gaps. The current aquatic information on Duffins Creek is by no means complete and there are a number of data gaps that will influence our ability to effectively manage the fisheries resources and track changes over time. These gaps include the following: A lack of a good hydrology model for baseflow and frequent flows in the watershed. Management of the flow regime within the watershed is critical to the protection of its resources, especially the aquatic ecosystem. Creation of a continuous simulation model to allow prediction of baseflows and frequent flows is critical to developing an understanding of what will be necessary to protect the watershed. Table 2: Duffins Creek Estuarine Marsh Cumulative Species List COMMON NAME SCIENTIFIC NAME alewife Alosa pseudoharengus gizzard shad Dorosoma cepedianum rainbow trout Oncorhynchus mykiss rainbow smelt Osmerus mordax northern pike Esox lucius white sucker Catostomus commersoni carp Cyprinus carpio golden shiner Notemigonus crysoleucas emerald shiner Notropis antherinoides common shiner Luxilus cornutus spottail shiner Notropis hudsonius spotfin shiner Notropis spilopterus bluntnose minnow Pimephales notatus fathead minnow Pimephales promelas blacknose dace Rhinichthys atratulus longnose dace Rhinichthys cataractae creek chub Semotilus atromaculatus brown bullhead Ameiurus nebulosus white perch Moreone americana white bass Morone chrysops rock bass Ambloplites rupestris pumpkinseed Lepomis gibbosus smallmouth bass Micopterus dolomieui largemouth bass Micropterus salmoides yellow perch Perca flaveseens johnny darter Etheostoma nigrum logperch Percina caprodes Source: TRCA, OMNR Understanding and managing angling pressure to determine if it is impacting fish communities is critical. To answer this question, spring and summer creek surveys are needed to quantify angling pressure. 11
Summary Of all the watersheds within the TRCA jurisdiction, Duffins Creek has one of the most intact fish communities and may have the potential for successful reintroduction of Atlantic salmon. Since initial settlement, many riparian areas that were once deforested have been left to regenerate. Much of this regeneration was not planned but occurred ostensibly because many areas in the watershed were unsuitable for agriculture and were subsequently abandoned. Now, because there has been little development in the mid- to upper reaches, the stream community is in relatively good condition. Nevertheless, there are several measures that can be implemented to better manage the aquatic ecosystem including improving fish passage where appropriate, planting woody riparian vegetation and reforestation of table lands. 12
References Eyles, N., J. Boyce and R. Gerber, 1997. Hydrogeological Study of the North Pickering Development Corporation Lands and the Duffins Creek Watershed. Prepared for the North Pickering Development Corporation. (CD Rom available from TRCA) HBT AGRA Ltd., 1994. Seaton Lands as a Natural Ecosystem. Report to the Seaton Interim Planning Team. 139pp and Appendix. Jones, M. and M. Guy, 1997. Seaton Lands Stream Assessment: Aquatic Habitat and Fisheries. Prepared for the North Pickering Development Corporation. (CD Rom available from TRCA) Karr, J.R., 1981. Assessment of Biotic Integrity Using Fish Communities. Fisheries 6:21-27. Ontario Department of Planning and Development (ODPD), 1956. Rouge, Duffin, Highland, Petticoat Valley Conservation Report. Toronto, Ontario. Sibul, U., K.T. Wong and D. Vallery, 1977. Groundwater Resources of the Duffins Creek-Rouge River Drainage Basins. Water Resources Report: 8. Ministry of the Environment, Water Resources Branch. Toronto, Ontario. Steedman, R.J., 1988. Modification and Assessment of an Index of Biotic Integrity to Quantify Streams in Southern Ontario. Canadian Journal of Fisheries and Aquatic Science 54: 492-501. Stephenson, T., 1988. Fish Utilization of Toronto Area Costal Marsh Areas. M.Sc. Thesis, Department of Zoology, University of Toronto, Toronto ON, Canada. 222p. Toronto and Region Conservation Authority (TRCA), 1999. Glen Major Complex Management Plan: Phase 1-Background Report. Downsview, Ontario. 13