Chapter 12: Sustaining Aquatic Biodiversity. December 11, 2013

Transcription

1 Chapter 12: Sustaining Aquatic Biodiversity December 11, 2013

2 Case Study: Lake Victoria and decline of cichlids Cichlids: feed on detritus, algae, zooplankton 80% of 500 fish in Lake. Lost 200 species. 1. Nile perch: large, predatory fish. Introduced to lake to stimulate export to Europe. -Increased poverty and malnutrition by putting small-scale fisheries and and vendors out of business -Local forests depleted: Perch needed to be smoked not sun-dried

3 Case Study: Lake Victoria and decline of cichlids 2. Algal blooms because of nutrient runoff from farms, deforested land, untreated sewage, and declining population of cichlids. 3. Invasion by water hyacinth -Block sunlight, deprive fish and plankton of oxygen, reduce diversity of aquatic plants -Control?

4 Case Study: Lake Victoria and decline of cichlids 4. Nile perch population is declining: reduced its own food supply and overfishing -Allow cichlids population to recover?

5 3 patterns of marine biodiversity: 1. Greatest marine biodiversity occurs in coral reefs, estuaries, and deep-ocean floor. 2. Biodiversity is higher near coasts than in the open sea because of the greater variety of of producers in habitats in coastal areas. 3. Biodiversity is higher in the bottom region of the ocean than in the surface region because of the greater variety of habitats and food sources on the ocean floor.

6 Value of Aquatic Biodiversity Ecological Economic est. $21 trillion/year Others? Food source for 3.5 billion people. Antibiotic and anticancer chemicals Pharmaceuticals Others?

7 H Human Impacts on Aquatic Biodiversity I P HIPPO Habitat loss and degradation! > Coral reefs > Mangrove swamps > Coastal wetlands > Rivers *90% of fish living in ocean spawn in these areas. P O Why are these areas under most intense pressure from human activity?

8 Human Impacts on Aquatic Biodiversity 20% coral reefs destroyed, 20% damaged 15% seagrass beds disappeared Dying kelp beds

9 Human Impacts on Aquatic Biodiversity Rising sea level cm in last 100 years *global warming Destroy more coral reefs, swamp low-lying islands, cover wetlands

10 Human Impacts on Aquatic Biodiversity Mangrove forests shrimp farming timber recreation and ecotourism flooding

11 Trawler fishing boats "submerged bulldozers" Used to harvest bottom fish and shellfish Each year, disturb 150x clear cut forest area

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13 Freshwater habitat disruption *Dams holdback 3-6 times amount that flows in natural rivers. *Humans take twice as much water each year from rivers and lakes -agriculture -urban use

14 Aquatic Invasive Species accidental or deliberate introduction bioinvaders cause of about 2/3 fish extinction in US ( ) Where do they come from? > ballast water > floating plastic H I P P O

15 Aquatic Invasive Species Asian swamp eel > dumping of a home aquarium > eats anything > breathe air (not affected by waterborne poisons > can travel across land into other waters Purple loosestrife > ballast water and import for medicinal use from Europe > introduced predators to loosestrife to reduce population (biological control) Zebra mussel > Native distribution in Russia, spread to Western Europe, than in Great Lakes (probably from ballast water) > reproduce quickly > kill other mussel species > clog pipes

16 Population Growth and Pollution 2006: 45% of world's population lived along or near the coastal zone. pollution (nitrogen and phosphorous, run-off) recreational use of freshwater systems > input of sediment toxic pollutatns from industrial and urban areas plastic items > wildlife ingest, become entangled in, or are poisoned by them. H I P P O

17 Overfishing and Extinction 75% of world's commercially valuable marine fish species are overfished or fished near their sustainable limits. commercial extinction: no longer profitable to continue fishing modern industrial fishing can cause 80% depletion of a target fish species in only years. H I P P O

18 Overfishing and Extinction Overfishing is usually only a temporary depletion, as long as depleted areas are allowed to recover changed industry: fishing with large fleets (millions of boats), high profit overfishing --> economic and ecological loss Shift from larger fish (tuna, swordfish) to smaller fish bycatch

19 Overfishing and Extinction Fish threatened with biological extinction > overfishing > water pollution > wetland destruction > excessive removal of freshwater 34% marine and 71% of freshwater fish species face biological extinction within lifetime. *Most threatened by human activities with extinction

20 Why is it difficult to protect aquatic biodiversity? 1. Human ecological footprint is expanding so rapidly, difficult to monitor the impacts. 2. Much of the damage is not visible to most people 3. Many people incorrectly view the sea as an inexhaustible resource that can absorb an almost infinite amount of waste and pollution. 4. Most of world's ocean lies outside the legal jurisdiction of any country > *tragedy of the commons

21 Protecting and Sustaining Marine Biodiversity 1. National and international laws and treaties > CITES (Convention on International Trade in Endangered Species) > 1979 Global Treaty on Migratory Species > US Marine Mammal Protection Act of 1973 > US Endangered Species Act of 1973* > US Whale Conservation and Protection Act of 1976 > 1995 International Convention on Biological Diversity *For homework, look up the 2 (not ESA since we already looked at it) national and international laws and treaties. Write a paragraph that summarizes the goals, how it achieves the goals, and its enforcement. Also include some opinions or criticisms about the law/treaty.

22 Protecting and Sustaining Marine Biodiversity 1. National and international laws and treaties > Turtles: 6 of 7 species endangered because of human activity. Use of TED (turtle exclusion device) required for shrimp trawlers (US) Economic tools «Sea turtles worth more alive than dead (ecotourism v. selling meat, leather, eggs) «Manatees can help manage water hyacinth

23 Case Study: Commercial Whaling Cetaceans Easy to kill: large, need to surface to breath. Over-harvesting reduced 8 of 11 species to commercial extinction International Whaling Commission (IWC): mission to regulate whaling industry by setting quotas > not enough data to support quotas > no enforcement 1970: US stopped all whaling and banned imports of whale products Established moratorium on commercial whaling (government of countries in IWC) Japan, Norway, and Iceland continue to kill for "scientific purposes" > Commercial > economy and culture December 11, 2013

24 Case Study: Commercial Whaling Should whaling be allowed? Yes: > Proposed hunting levels too low to deplete stocks again > System to monitor and enforce whaling practices No: > Whales are peaceful, intelligent, sensitive, social mammals (ethical obligation?) > recovery? Estimation not as accurate > opening door for any commercial whaling lead to widespread > worth more alive than dead (whale watching) December 11, 2013

25 *Whales fit typical scenario of species that are very vulnerable to extinction -Economically valuable to humans (meat, oil, bones) -k-selected species (25 years to reach maturity, only reproduce 2-5 years) -HUGE: easy to spot -group together in feeding grounds

26 Protecting and Sustaining Marine Biodiversity 1. National and international laws and treaties 2. Marine Sanctuaries > International law: country's offshore fishing zone extends 370 km from shores Exclusive economic zones: foreign fishing vessels can take certain quotas of fish w/in zones (36% ocean surface, 90% fishstocks) high seas: ocean outside jurisdiction Instead of protecting, governments promote overfishing, subsidize new fishing fleets, failed to protect water and fish. *Profit!

27 Protecting and Sustaining Marine Biodiversity 1. National and international laws and treaties 2. Marine Sanctuaries > Marine protected areas (MPAs) 1300 MPA, 200 in US partially protected from human activity allow dredging, trawler fishing, recreation > Marine reserves fully protected: no extraction and alteration 20 nations Full protection works, and works fast (with in 2-4 years): «fish population x2 «fish size grows by 1/3 «fish reproduction x3 «species diversity increases by 1/4 Benefits fisheries: fish and larvae move out of reserves > zoning rules establish zones with in an area that allows for certain activities in areas and requires permits for others Great Barrier Reef Marine park

28 Protecting and Sustaining Marine Biodiversity 1. National and international laws and treaties 2. Marine Sanctuaries > 0.3% of world's ocean area is in marine reserve to increase to 30%, cost $12-14 billion/year US: G. W. Bush created Northwestern Hawaiian Marine National Monument. Protects 360,000 sq. km of federal water around Hawaiian islands > Future: how big do reserves have to be? how many do we need? where should they be? how can the reserves be connected? > Opposition to reserves: recreation fisheries

29 Protecting and Sustaining Marine Biodiversity 1. National and international laws and treaties 2. Marine Sanctuaries 3. Integrated coastal management > Community based effort to develop and use coastal resources more sustainably > gather scientists, conservationists, local, business groups, developers, politicians > *balance of preservation and economic/social needs Short term trade-offs for long-term ecological/ economic benefits Used in zoning in Great Barrier Reef Marine Park

30 Protecting and Sustaining Marine Biodiversity 1. National and international laws and treaties 2. Marine Sanctuaries 3. Integrated coastal management 4. Revamping US Ocean Policy > Need for greater protection of US coastal waters > National policy? > Ocean research > centralize fragmented management of oceans > marine reserves w/corridors > manage coastal development > reorient fisheries: sustain ecosystem rather than catch limits > program to increase public awareness

31 Managing and Sustaining Marine Fisheries

32 Managing and Sustaining Marine Fisheries December 11, 2013

33 Managing Marine Fisheries by improving estimate of fish population: maximum sustained yield (MSY): projects maximum # of fish that can be harvested annually w/o causing population to drop > difficult because population size hard to determine growth rate also difficult to estimate > can also cause effects in other organisms optimum sustained yield (OSY): takes into account interactions with other species, provide more room for error > OSY < MSY > economic, social, ecological factors > Greatest benefit for nation Multispecies management: takes into account interactions of species > manage multiple species under same plan instead of one at a time large marine systems: integrated computer model to manage multispecies fisheries

34 Uncertainty underlies all of these strategies: population size difficult to estimate can't predict effects of reducing population size Trend towards precautionary principle: reducing fish harvests, close overfished areas to allow recover *wait until more information tells them that they can take more fish sustainably*

35 Regulating fish harvest: Cooperation Historically, communities (not government) have established allotment and enforcement systems to sustain fisheries, jobs, and communities. Growth of fishing industry = need for regulation replace community management with comanagement: coastal community and government work together to manage fisheries > government sets quotas, seasons, type of fishing gear > community allocates and enforces quota among members

36 Protecting, sustaining, and restoring wetlands Examples of wetlands: Coastal wetlands (mangroves, estuaries) Marshes Peat Bogs

37 Wetland protection in the US Louisiana has 40% of nation's saltwater marshes. Lost to: reduced sediment flow by levees and dams global warming and rising sea levels Wetlands are filled in and destroyed to be used for: land for urban development land for crops rice fields reduce disease (mosquitos) extract minerals, oil, natural gas W/loss of wetlands, also lose biodiversity commercial values: fish, shellfish migratory paths of birds

38 Wetland protection in the US US policy: "Zero net loss" in function and value of coastal and inland wetlands. But people still want to use wetland areas. Compromise? Policy? mitigation banking: can destroy wetland as equal area of asme type is created or restored > Is restoration as good as protection? probably not not as complex not monitored well *developers can buy credits from private wetland banks > credit from restoring wetlands > $300 million

39 Restoring the Florida Everglades (p ) 1. What is the Everglades? 2. What factors contributed to the degradation and destruction of the Everglades? How much was destroyed? 3. Why was the Kissimmee River altered and what was its effect? 4. What was the initial solution in 1947 and why did this not work? 5. Where does all of the freshwater go!? 6. Wha are the goals of CERP? 7. Name 3 shortcomings of CERP 8. How do you see the interplay of politics and environmental science in this case study?

40 Managing Lakes *Look at Case Study on great Lakes and invasive species!

41 Managing River Basins Disrupted by: overfishing pollution dams water withdrawal for irrigation

42 Managing River Basins Dams: Columbia River Pros: provide hydroelectric power water for irrigation and urban areas Cons: reduces fish population (especially migratory fish like salmon: interrupt life cycle) Destroy habitat reduce flow of sediment and nutrients

43 Managing and Sustaining Freshwater Fisheries Strategies: encourage populations of commercial and sport fish species (why sport fish?) prevent overfishing reduce populations of less desirable specie How? > fishing season > regulate # and size of fish taken (why?) > build reservoirs and farm ponds > fertilize nutrient-poor lakes and ponds > create/protect spawning sites > manage sediment, aquatic plants, dams

44 Protecting Wild and Scenic Rivers in US National Wild and Scenic Rivers Act protects rivers and river segments w/ scenic, recreational, geological, wildlife, historical, or cultural value > wild rivers: inaccessible, untamed, not permitted to be widened, straightened dredged, filled, or dammed > scenic rivers: accessible in small areas, no dams, mostly undeveloped > recreational rivers: readily accessible, some dams or some development *only 0.2% river length included 2% free-flowing 17%: dams and reservoirs

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