Chapter 13 Sustaining Aquatic Biodiversity AQUATIC BIODIVERSITY We

Chapter 13 Sustaining Aquatic Biodiversity

AQUATIC BIODIVERSITY Ø We know fairly little about the biodiversity of the world’s marine and freshwater systems. l l The greatest marine biodiversity occurs in coral reefs, estuaries and the deep ocean floor. Biodiversity is higher near the coast and surface because of habitat and food source variety. Ø The world’s marine and freshwater systems provide important ecological and economic services.

HUMAN IMPACTS ON AQUATIC BIODIVERSITY Ø Human activities have destroyed, disrupted or degraded a large proportion of the world’s coastal, marine and freshwater ecosystems. l l Approximately 20% of the world's coral reefs have been destroyed. We have destroyed more than 1/3 of the world’s mangrove forests for shipping lanes.

HUMAN IMPACTS ON AQUATIC BIODIVERSITY Ø Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Figure 12 -2

HUMAN IMPACTS ON AQUATIC BIODIVERSITY Ø Harmful invasive species are an increasing threat to marine and freshwater biodiversity. l Bioinvaders are blamed for about 2/3 of fish extinctions in the U. S. between 1900 -2000. Ø Almost half of the world’s people live on or near a coastal zone and 80% of ocean water pollution comes from land-based human activities.

Aquatic Invasive Species Zebra Mussels Water Hyacinth

Population Growth and Pollution Ø Each year plastic items dumped from ships and left as litter on beaches threaten marine life. Figure 12 -3

Overfishing and Extinction: Gone Fishing, Fish Gone Ø About 75% of the world’s commercially valuable marine fish species are over fished or fished near their sustainable limits. l l 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.

Fish farming in cage Trawl flap Trawler fishing Spotter airplane Sonar Purse-seine fishing Trawl lines Fish school Trawl bag Long line fishing Drift-net fishing Float Buoy Lines with hooks Deep sea aquaculture cage Fish caught by gills Fig. 12 -A, p. 255

Why is it Difficult to Protect Aquatic Biodiversity? Ø Rapid increasing human impacts, the invisibility of problems, citizen unawareness, and lack of legal jurisdiction hinder protection of aquatic biodiversity. l l l Human ecological footprint is expanding. Much of the damage to oceans is not visible to most people. Many people incorrectly view the oceans as an inexhaustible resource.

PROTECTING AND SUSTAINING MARINE BIODIVERSITY Ø Laws, international treaties, and education can help reduce the premature extinction of marine species. Ø Since 1989 the U. S. government has required offshore shrimp trawlers to use turtle exclusion devices. l Sea turtle tourism brings in almost three times as much money as the sale of turtle products.

PROTECTING AND SUSTAINING MARINE BIODIVERSITY Ø Six of the world’s seven major turtle species are threatened or endangered because of human activities. Loggerheads: The Epic Journey Figure 12 -4

PROTECTING AND SUSTAINING MARINE BIODIVERSITY Ø A "Turtle Excluder Device" is a grid of bars with an opening either at the top or the bottom of the trawl net. The grid is fitted into the neck of a shrimp trawl. Small animals such as shrimp pass through the bars and are caught in the bag end of the trawl. When larger animals, such as marine turtles and sharks, are captured in the trawl they strike the grid bars and are ejected through the opening. Turtle Excluder Devices (TEDs) - NOAA Fisheries

PROTECTING AND SUSTAINING MARINE BIODIVERSITY Ø Fully protected marine reserves make up less than 0. 3% of the world’s ocean area. l Studies show that fish populations double, fish size grows by almost a third, reproduction triples and species diversity increases by almost one fourth. Ø Some communities work together to develop integrated plans for managing their coastal areas.

Revamping Ocean Policy Ø Two recent studies called for an overhaul of U. S. ocean policy and management. l l l 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.

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

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

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

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

Case Study: Restoring the Florida Everglades Ø The world’s largest ecological restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities. l l l 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. Invasive snakes have greatly reduced biodiversity

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

Pythons Removed From The Everglades The chart below shows the number of pythons removed from the park and neighboring areas between 1995 and 2010. Researchers say the slight decrease in the number of pythons captured in 2010 might be the result of a severe freeze in January of that year. Source: Michael Dorcas/Davidson University http: //www. npr. org/2012/01/30/146088909/invasive-pythons-put-squeeze-on-everglades-animals

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

PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS Ø Dams can provide many human benefits but can also disrupt some of the ecological services that rivers provide. l l l 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.

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

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. 12 -11, p. 267