Sustaining Aquatic Biodiversity. Chapter 12

Transcription

1 Sustaining Aquatic Biodiversity Chapter 12

2 Oceans cover most of the Earth s surface The oceans influence global climate, team with biodiversity, facilitate transportation and commerce, and provide resources for us They cover 71% of Earth s surface and contain 97% of Earth s surface water Oceans influence the atmosphere, lithosphere, and biosphere

3 The oceans contain more than water Ocean water is 96.5% water Plus, ions of dissolved salts Evaporation removes pure water and leaves a higher concentration of salt Nutrients (nitrogen and phosphorus) Dissolved gas Oxygen is added by plants, bacteria, and atmospheric diffusion

4 Ocean water is vertically structured Temperature declines with depth Heavier (colder saltier) water sinks Light (warmer and less salty) water remains near the surface Temperatures are more stable than land temperatures Water s high heat capacity It takes much more heat to warm water than air Oceans regulate the earth s climate They absorb and release heat Ocean s surface circulation

5 Surface zone The ocean has several layers Warmed by sunlight and stirred by wind Consistent water density Pycnocline = below the surface zone Density increases rapidly with depth Deep Zone = below the pycnocline Dense, sluggish water Unaffected by winds, storms, sunlight, and temperature

6 Ocean water flows horizontally in currents Currents = the ocean is composed of vast riverlike flows Driven by density differences, heating and cooling, gravity, and wind Influence global climate and El Niño and La Niña Transport heat, nutrients, pollution, and the larvae of many marine species Some currents such as the Gulf Stream are rapid and powerful The warm water moderates Europe s climate

7 The upper waters of the oceans flow in currents

8 Surface winds and heating create vertical currents Upwelling = the vertical flow of cold, deep water towards the surface High primary productivity and lucrative fisheries Also occurs where strong winds blow away from, or parallel to, coastlines Downwellings = oxygen-rich water sinks where surface currents come together

9 Salinity of the Oceans Mapping the Trends

10 Salinity Map

11 Distribution of Sea Salinity 1. Using colored pencils, create a legend by choosing a different color for each salinity value on your isohaline map. (ppt) 2. Name the continents and countries. 3. Using your color key, fill in the regions of the ocean that correspond to the different surface water salinity values 4. Answer the accompanying questions. This lab will be graded on ACCURACY, not completion.

12 Questions 1. List the ocean regions with the highest sea surface salinity. 2. List the ocean regions with lowest sea surface salinity. 3. Describe the distribution of sea surface salinity patterns as a function of latitude. 4. Describe the distribution of sea surface salinity patterns as a function of surface currents.

13 Questions (continued) 5. What are the major ions contributing to ocean salinity and their relative abundances? 6. What is the impact from rising ocean surface temperatures to the organisms in the euphotic zone? Be detailed and relate your answer to salinity.

14 Review: Principles of Sustainability 1. Reliance on solar energy 2. Biodiversity 3. Population Control 4. Nutrient Recycling

15 Economic Importance of Aquatic Ecosystems The economic importance of aquatic diversity is the estimate of the value of their ecological services which is $21 trillion a year. At least 3.5 billion people depend on the seas for their primary source of food; this number could double to 7 billion in 2025.

16 What is aquatic biodiversity? Aquatic biodiversity refers to the composition of plants and animals in the fresh and salt waters of the planet. Freshwater Saltwater Wetlands, Estuaries

17 Ocean Biodiversity We have only explored only 5% of our oceans and know very little about it s biodiversity Human activities are undermining aquatic biodiversity by destroying and degrading coastal wetlands, coral reefs, seagrass beds, kelp beds, mangroves and the ocean bottom.

18 Marine Ecological Services Many medicines have been developed from sea organisms: sponges, anemones, puffer fish, porcupine fish, seaweeds, etc. The waters are used for extensive recreational activities, and mention commercial transportation.

19 Oceans provide transportation routes Humans have interacted with oceans for thousands of years Moving people and products over vast distances Accelerated global reach of cultures Has substantial impact on the environment Moves resources around the world Ballast water transplants organisms, which may become invasive

20 We extract energy from oceans Crude oil and natural gas Oil spills damage fisheries Methane hydrate = a potential energy source Ice-like solid methane embedded in water crystals Renewable energy sources, such as waves, tides, heat

21 We extract minerals from oceans Minerals such as sand, gravel, sulfur, calcium carbonate, and silica Rich deposits of copper, zinc, silver, and gold Manganese nodules are scattered along the ocean s floor But, they are too hard to currently mine

22 Human Impact on Aquatic Biodiversity Human impact on aquatic biodiversity can be summarized as: H: Habitat Loss I: Invasive Species P: Population Growth P: Pollution O: Overfishing (extinction)

23 Loss of Habitat Loss of habitat can be intentional such as the destruction of wetlands or estuarine environments, it can also be an effect from pollution

24 Invasive Species Invasive species are introduced to water in ports and off-shore from ballast water zebra mussels

25 Marine pollution threatens resources Even into the mid-20th century, coastal U.S. cities dumped trash and untreated sewage along their shores Oil, plastic, chemicals, excess nutrients make their way from land into oceans Raw sewage and trash from cruise ships Abandoned fishing gear from fishing boats

26 Nets and plastic debris endangers marine life Plastic items dumped into the sea harm or kill wildlife Plastic is non-biodegradable Drifts for decades Washes up on beaches Wildlife eat it or get entangled Marine debris affects people Equipment damage The 2006 Marine Debris Research, Prevention and Reduction Act

27 Oil pollution comes from spills of all sizes Major oils spills make headlines and cause serious environmental problems Most pollution comes from small sources Boat leakage and runoff from land Naturally occurring leaks from the seabed

28 Oil pollution has decreased Governments have implemented more stringent regulations The U.S. Oil Pollution Act of 1990 Creates a $1 bil prevention and cleanup fund Requires all ships have double hulls by 2015 Recently, oil spills have decreased even though the oil industry resists such safeguards

29 Toxic pollutants contaminate seafood Mercury contamination From coal combustion and other sources Bioaccumulates and biomagnifies Dangerous to young children and pregnant or nursing mothers Avoid eating swordfish, shark, and albacore tuna Eat seafood low in mercury (catfish, salmon, canned light tuna) Avoid seafood from areas where health advisories have been issued

30 Excess nutrients cause algal blooms Harmful algal blooms = nutrients increase populations of algae that produce powerful toxins Red tide = algal species produce reddish pigments that discolor water Illness and death to wildlife and humans Economic losses to fishing industries and beach tourism

31 Emptying the oceans We are placing unprecedented pressure on marine resources Half the world s marine fish populations are fully exploited 25% of fish population are overexploited and heading to extinction Total fisheries catch leveled off after 1998, despite increased fishing effort It is predicted that populations of all ocean species we fish for today will collapse by the year 2048

32 The total global fisheries catch has increased

33 We have long overfished People began depleting sea life centuries ago Some species hunted to extinction: Steller s sea cow, Atlantic gray whale, Caribbean monk seal Overharvesting of Chesapeake Bay oyster beds led to the collapse of its fishery, eutrophication, and hypoxia Decreased sea turtle populations causes overgrowth of sea grass and can cause sea grass wasting disease

34 Fishing has industrialized Factory fishing = highly industrialized, huge vessels use powerful technologies to capture fish in huge volumes Even process and freeze their catches while at sea

35 Driftnets for schools of herring, sardines, mackerel, sharks Longline fishing for tuna and swordfish Trawling for pelagic fish and groundfish

36 Fishing practices kill nontarget animals By-catch = the accidental capture of animals Driftnetting drowns dolphins, turtles, and seals Fish die from air exposure on deck Banned or restricted by many nations Longline fishing kills turtles, sharks, and albatrosses 300,000 seabirds die each year

37 Trawling Bottom-trawling destroys communities Likened to clear-cutting and strip mining

38 Modern fishing fleets deplete marine life rapidly Grand Banks cod have been fished for centuries Catches more than doubled with immense industrial trawlers Record-high catches lasted only 10 years

39 Industrialized fishing depletes populations Catch rates drop precipitously with industrialized fishing 90% of large-bodied fish and sharks are eliminated within 10 years Populations stabilize at 10% of their former levels Marine communities may have been very different before industrial fishing Removing animals at higher trophic levels allows prey to proliferate and change communities

40 Oceans today contain only one-tenth of the large-bodied animals they once did

41 Several factors mask declines Industrialized fishing has depleted stocks, global catch has remained stable for the past 20 years Fishing fleets travel longer distances to reach less-fished portions of the ocean Fleets spend more time fishing and have been setting out more nets and lines, increasing effort to catch the same number of fish Improved technologies: faster ships, sonar mapping, satellite navigation, thermal sensing, aerial spotting Data supplied to international monitoring agencies may be false

42 We are fishing down the food chain Figures on total global catch do not relate the species, age, and size of fish harvested As fishing increases, the size and age of fish caught decline 10-year-old cod, once common, are now rare As species become too rare to fish, fleets target other species Shifting from large, desirable species to smaller, less desirable ones Entails catching species at lower trophic levels

43 Consumer choices influence fishing practices Buy ecolabeled seafood Dolphin-safe tuna Consumers don t know how their seafood was caught Nonprofit organizations have devised guides for consumers Best choices: farmed catfish and caviar, sardines, Canadian snow crab Avoid: Atlantic cod, wildcaught caviar, sharks, farmed salmon

44 Overfishing and Extinction: Gone Fishing, Fish Gone About 75% of the world s commercially valuable marine fish species are over fished or fished near their sustainable limits. Big fish are becoming scarce. Smaller fish are next. We throw away 30% of the fish we catch. We needlessly kill sea mammals and birds.

45 Cod are groundfish They live or feed along the bottom Halibut, pollock, flounder Cod eat small fish and invertebrates They grow to cm long and can live 20 years Inhabit cool waters on both sides of the Atlantic There are 24 stocks (populations) of cod

46 Central Case: collapse of the cod fisheries No fish has more impact on human civilization than the Atlantic cod Eastern Canadians and U.S. fishermen have fished for cod for centuries Large ships and technology have destroyed the cod fishery Even protected stocks are not recovering

47 PROTECTING AND SUSTAINING MARINE BIODIVERSITY Six of the world s seven major turtle species are threatened or endangered because o human activities. Figure 12-4

48 Case Study: The Florida Manatee and Water Hyacinths Manatee can eat unwanted Water Hyacinths. Endangered due to: Habitat loss. Entanglement from fishing lines and nets. Hit by speed boats. Stress from cold. Low reproductive rate Figure 12-B

49 Case Study: Commercial Whaling After many of the world s whale species were overharvested, commercial whaling was banned in 1960, but the ban may be overturned. Figure 12-6

50 Case Study: Commercial Whaling Despite ban, Japan, Norway, and Iceland kill about 1,300 whales of certain species for scientific purposes. Although meat is still sold commercially. Figure 12-5

51 Based on maximum sustained yield Fisheries management Maximal harvest while keeping fish available for the future Managers may limit the harvested or restrict gear used Despite management, stocks have plummeted It is time to rethink fisheries management Ecosystem-based management Shift away from species and toward the larger ecosystem Consider the impacts of fishing on habitat

52 To Protect and Serve We can protect and sustain marine biodiversity by using laws, international treaties, and education. First identify and protect species that are endangered and/or threatened. Clean up aquatic environments

53 Why is it so hard? 1. Our human footprint is so large and is growing exponentially; 2. Damage to the ocean is not usually visible to the naked eye; 3. People view the ocean as an inexhaustable resource; 4. The ocean is outside the legal jurisdiction of any one country.

54 We can protect areas in the ocean Marine protected areas (MPAs) = established along the coastlines of developed countries Still allow fishing or other extractive activities Marine reserves = areas where fishing is prohibited (less than 0.3% of the ocean) Leave ecosystems intact, without human interference Improve fisheries, because young fish will disperse into surrounding areas

55 Reserves work for both fish and fisheries Found that reserves do work as win-win solutions Overall benefits included Boosting fish biomass Boosting total catch Increasing fish size Benefits inside reserve boundaries included Rapid and long-term increases in marine organisms and decrease mortality and habitat

56 How should reserves be designed? 20-50% of the ocean should be protected in no-take reserves How large? How many? Where? Involving fishers is crucial fisheries in coming with these answers

57 Areas outside reserves also Benefits included benefit A spillover effect when individuals of protected species spread outside reserves Larvae of species protected within reserves seed the seas outside reserves Improved fishing and ecotourism

58 Marine Management There are a number of ways to manage marine fisheries more sustainably and protect marine biodiversity. A country has jurisdiction over the ocean up to 200 miles from it s coast. Rather than protecting the marine environment, countries tend to promote fishing.

59 Integrated Coastal Management Integrated Coastal Management (ICM) is an idea or management policy based on a community approach. Private sector as well as the public sector work together to identify problems and share the burden of restoration or management.

60 Managing Fisheries Fishery Regulations: set catch limits well beyond maximum sustainable yield improve monitoring and enforcement Economic Approach: reduce or eliminate subsidies charge fees for harvesting fish and shellfish from public areas certify sustainable fisheries

61 More Management Protected Areas: establish no-fishing zones establish more reserves rely on integrated coastal management Consumer Education: label sustainably harvested fish educate about overfished and endangered species

62 Bycatch: Management (cont.) streamline fishing techniques and tools Aquaculture: restrict coastal locations for fish farms control pollution (CWA) depend on herbivorous fish species Non-native Invasions: kill organisms in ship ballast water, filter ballast water or dump in open sea

63 Legislation: Each group will discuss the event and the impact International Convention of the Regulation of Whaling US ban on whaling and importation of whale products US Marine Mammel Protection Act US Endangered Species Act Convention on International Trade in Endangered Species (CITES) Global Treaty on Migratory Species

64 Freshwater Freshwater fisheries, lakes and rivers can be protected, sustained, and even restored by building and protecting populations of desirable species, by prevention of overfishing, and by decreasing populations of less desirable species. Laws must be enacted and funded to protect scenic rivers; they must be protected from development and dam construction projects.

65 Case Study: Lake Victoria Lake Victoria is a shallow lake in East Africa Before 1980, the lake had 500 species of unique fish. 80% of the fish population was a small fish known as cichlids which feed on detritus, zooplankton and algae Since 1980, more than 200 species have become extinct

66 Cause and Effect of Loss of Biodiversity First: Nile perch, a predatory fish, was introduced to the lake to stimulate exports and the population exploded Second: The nutrient runoff from nearby fields, deforested land and untreated sewage, as well as a decline in the cichlids has lead to frequent algal blooms.

67 More Factors Third: An invasive species of water living plants has blocked the photic zone which has lead to lower D.O. Fourth: The populations of Nile Perch are decreasing because of a reduction in the smaller feeder fish.

68 PROTECTING AND SUSTAINING MARINE BIODIVERSITY Fully protected marine reserves make up less than 0.3% of the world s ocean area. Studies show that fish populations double, size grows by almost a third, reproduction triples and species diversity increases by almost one fourth. Some communities work together to develop integrated plans for managing their coastal areas.

69 Revamping Ocean Policy Two recent studies called for an overhaul of U.S. ocean policy and management. Develop unified national policy. Double federal budget for ocean research. Centralize the National Oceans Agency. Set up network of marine reserves. Reorient fisheries management towards ecosystem function. Increase public awareness.

70 MANAGING AND SUSTAINING MARINE FISHERIES There are a number of ways to manage marine fisheries more sustainably and protect marine biodiversity. Some fishing communities regulate fish harvests on their own and others work with the government to regulate them. Modern fisheries have weakened the ability of many coastal communities to regulate their own fisheries.

71 Solutions Managing Fisheries Fishery Regulations Set catch limits well below the maximum sustainable yield Improve monitoring and enforcement of regulations Economic Approaches Sharply reduce or eliminate fishing subsidies Charge fees for harvesting fish and shellfish from publicly owned offshore waters Certify sustainable fisheries Protected Areas Establish no-fishing areas Establish more marine protected areas Rely more on integrated coastal management Consumer Information Label sustainably harvested fish Publicize overfished and threatened species Bycatch Use wide-meshed nets to allow escape of smaller fish Use net escape devices for sea birds and sea turtles Ban throwing edible and marketable fish back into the sea Aquaculture Restrict coastal locations for fish farms Control pollution more strictly Depend more on herbivorous fish species Nonnative Invasions Kill organisms in ship ballast water Filter organisms from ship ballast water Dump ballast water far at sea and replace with deep-sea water Fig. 12-7, p. 261

72 Wetlands Wetlands can be protected, sustained, and restored by government regulations which prevent wetland loss. Destroyed wetlands can, also, be restored and adequately monitored for their protection. Development can be kept away from wetland areas and control of nonnative species needs to be instituted to prevent invasion into wetlands.

73 Enforcement Options Conservation means management of resources Preservation means management but you cannot disturb the area Restoration means you return area to the original condition (not very realistic) Remediation is a general term that means cleaning up (most common term used) Mitigation means repairing an affected area, usually by replacing it somewhere else (wetlands) Reclamation means you are recovering resources or land from contaminated sites (recovering metal from electronics)

74 PROTECTING, SUSTAINING, AND RESTORING WETLANDS Requiring government permits for filling or destroying U.S. wetlands has slowed their loss, but attempts to weaken this protection continue. Figure 12-8

75 Solutions Protecting Wetlands Legally protect existing wetlands Steer development away from existing wetlands Use mitigation banking only as a last resort Require creation and evaluation of a new wetland before destroying an existing wetland Restore degraded wetlands Try to prevent and control invasions by nonnative species Fig. 12-9, p. 264

76 Case Study: Restoring the Florida Everglades The world s largest ecological restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities. 90% of park s wading birds have vanished. Other vertebrate populations down 75-95%. Large volumes of water that once flowed through the park have been diverted for crops and cities. Runoff has caused noxious algal blooms.

77 Restoring the Florida Everglades The project has been attempting to restore the Everglades and Florida water supplies. Figure 12-10

78 PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS Lakes are difficult to manage and are vulnerable to planned or unplanned introductions of nonnative species. For decades, invasions by nonnative species have caused major ecological and economic damage to North America s Great lakes. Sea lamprey, zebra mussel, quagga mussel, Asian carp.

79 PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS Dams can provide many human benefits but can also disrupt some of the ecological services that rivers provide. 119 dams on Columbia River have sharply reduced (94% drop) populations of wild salmon. U.S. government has spent $3 billion in unsuccessful efforts to save the salmon. Removing hydroelectric dams will restore native spawning grounds.

80 PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS We can help sustain freshwater fisheries by building and protecting populations of desirable species, preventing overfishing, and decreasing populations of less desirable species. A federal law helps protect a tiny fraction of U.S. wild and scenic rivers from dams and other forms of development. National Wild and Scenic Rivers Act (1968).

81 Natural Capital Ecological Services of Rivers Deliver nutrients to sea to help sustain coastal fisheries Deposit silt that maintains deltas Purify water Renew and renourish wetlands Provide habitats for wildlife Fig , p. 267