Chapter 12 Sustaining Aquatic Biodiversity. Aquatic Biodiversity What do we know? Only have explored 5% of the oceans Greatest marine biodiversity occurs

Chapter 12

Sustaining Aquatic Biodiversity

Aquatic Biodiversity

What do we know? Only have explored 5% of the oceans Greatest marine biodiversity occurs in coral reefs,

estuaries and deep ocean floor. Biodiversity is higher by the coast then the open

sea Biodiversity is greater in the bottom region of the

ocean then the surface region

Aquatic Biodiversity

Values of Aquatic Biodiversity Provide us with an estimated $21 trillion a year At least 3.5 billion people depend on the oceans

for survival Many marine organisms have chemicals used in

medicines Freshwater systems provide services worth $1.7

trillion.

Human Impacts on Aquatic Biodiversity

Loss and degradation 90% of fish living in the oceans spawn in coral reefs,

mangroves, coastal wetlands or rivers. 20% of coral reefs have been destroyed. Up to 58% could

be lost by 2050. 15% of worlds seagrass beds have disappeared since

1995 Sea level is rising- over the past 100 years level has risen

by 10-25 cm Mangroves and wetlands have been lost to development Trawlers are destroying bottom ecosystems


Invasive Species Blamed for about 2/3 of fish extinctions in the US

between 1900 and 2000 and cost an average of $16 million per HOUR.

Most arrive in ballast water Examples:

Asian swamp eel eats many types of fish. It can withstand cold weather, drought, fires and predators because it can burrow. It can also breath air.


Population Growth and Pollution 2006 45% of the worlds population lives on or

near a coast. Estimated that 80% of ocean pollution comes

from land based activities Amount of nitrate fertilizers has doubled since 1860.

Excess nutrients can cause eutrophication which can lead to algae blooms and then fish die offs.

Toxic pollutants from industrial and urban areas Plastic pollution kills 1 million seabirds and 100,000

sea turtles.


Overfishing and Extinction Modern industrialized fishing can deplete marine life very

rapidly. Can cause 80% depletion of a target fish species in only 10-15 years.

Usually leads to commercial extinction. In 1992 Canada’s cod fishery collapsed. Still has not

recovered. 90% of the large open ocean fish have disappeared since

1950 Can cause bycatch – organisms caught unintentionally in

nets.


Why is it difficult to protect? Human ecological footprint is expanding so

rapidly that it is difficult to monitor the impacts. Damage to oceans is not visible to humans People view the sea as an inexhaustible resource

that can absorb an infinite number of pollutants Most oceans lie outside the legal jurisdiction of

any country.

Protecting and Sustaining Marine Biodiversity

Legal and economic approaches 1975 CITES 1979 Global Treaty on Migratory Species US Marine Mammal Protection Act of 1972 US Endangered Species Act of 1973 US Whale and Conservation and Protection Act of

1973 1995 International Convention on Biological

Diversity

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-BFigure 12-B

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 12-6Figure 12-6

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.



Marine sanctuaries International law states that a country’s offshore

fishing zone extends to 370km (200 miles) from its shores. Exclusive economic zones: High seas: Marine protected areas (MPAs): Marine reserves:

Works and works fast – fish populations double, fish size grows by a third, fish reproduction triples, species diversity increases by a fourth.


Less than 0.3% of the world’s ocean area consists of fully protected marine reserves.

Scientist call for 30% of the ocean to become protected marine reserves.

World’s largest marine reserve was created in 2006. 360,000 sq km (140,000 sq miles) surrounding

some Hawaiian island.


Integrated coastal management Community based effort to develop and use coastal

resources more sustainably. Revamping US Ocean Policy

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

Make better estimates of fish populations. Traditional approach is to use a maximum

sustainable yield (MSY):

Hasn’t been very successful

Optimum sustainable yield (OSY):

Multispecies management:

Fig. 12-7, p. 261

SolutionsManaging Fisheries

Fishery Regulations

Set catch limits well below the maximum sustainable yield

Improve monitoring and enforcement of regulationsEconomic Approaches

Sharply reduce or eliminate fishing subsidies

Charge fees for harvesting fish and shellfish from publicly owned offshore waters

Certify sustainable fisheriesProtected 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

PROTECTING, SUSTAINING, AND RESTORING WETLANDS

US has lost more then ½ of its wetlands since 1900 Louisiana has 40% of US salt marshes. Much is

lost due to sinking. Dams and levees block sediment from flowing down Mississippi River that would normally be deposited. Plus, sea level is rising due to climate change.

Federal permits are required now to fill or dredge a wetland. This has help cut he average annual wetland lost by 80% since 1969.

Mitigation banking:

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.


Fig. 12-9, p. 264

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

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.

Restoring the Florida Everglades

The project has been attempting to restore the Everglades and Florida water supplies.


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 ($15 million/yr for chemical to kill

young), zebra mussel ($140 million a year), quagga mussel, Asian carp.


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.


We can help sustain freshwater fisheries by building and protecting populations of desirable species, preventing over-fishing, 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).

Fig. 12-11, p. 267

• Deliver nutrients to sea to help sustain coastal fisheries

• Deposit silt that maintains deltas

• Purify water

• Renew and renourish wetlands

• Provide habitats for wildlife

Natural Capital

Ecological Services of Rivers

Documents

Chapter 12 Sustaining Aquatic Biodiversity. Aquatic Biodiversity What do we know? Only have explored 5% of the oceans Greatest marine biodiversity occurs