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Ch. 11: Sustaining Aquatic Biodiversity
Terms in this set (37)
Protecting Whales: A Success Story... So Far (case study)
Whales are fairly easy to kill because of their large size in some cases and because of their need to come to the surface to breathe. Modern whaling methods have made this even easier. Whale harvesting, mostly in international waters, has followed the classic pattern of a tragedy of the commons, with whalers killing an estimated 1.5 million whales from 1925-1975. This overharvesting drove 8 of the 11 major species to commercial extinction
In 1946, the International Whaling C ommission (IWC) was established to regulate the whaling industry by setting annual quotas for various whale species to prevent overharvesting. But IWC quotas often were based on insufficient data or were ignored by whaling countries. Without enforcement powers, the IWC was not able to stop the decline of most commercially hunted whale species. In 1970, the US stopped all commercial whaling and banned all imports of whale products. Under pressure from conservationists and the governments of many nonwhaling nations, in 1986, the IWC began imposing a moratorium on commercial whaling. It worked. The estimated number of whales killed commercially worldwide dropped from 42,480 in 1970 --> 1,500 in 2009.
However, despite the moratorium, more than 33,000 whales were hunted and killed from 1986-2010, mostly by Japan and Norway, which had officially objected to and ignored the moratorium. In 2006, Iceland also stopped observing the moratorium. These three nations are pressuring the IWC to revise the moratorium and allow for resumed commercial hunting of some whale species.
Whales are just one part of the incredible diversity of aquatic species and their habitats that we must help to sustain. In this chapter, we discuss this important challenge.
What are the Major Threats to Aquatic Biodiversity?
...all made worse by the growth of the human population.
How Can We Protect and Sustain Marine Biodiversity?
We can help to sustain marine biodiversity by using laws and economic incentives to protect species, setting aside marine reserves to protect ecosystems, and using community-based integrated coastal management.
How Should We Manage and Sustain Marine Fisheries?
Sustaining marine fisheries will require improved monitoring of fish and shellfish populations, cooperative fisheries management among communities and nations, reduction of fishing subsidies, and careful consumer choices in seafood markets
Ways to sustain fisheries: (First, you need good estimates of the populations and growth rates to establish yield models)
- Regulate fish harvest
- Subsidies may encourage overfishing
- Consumer choices can help sustain fisheries
How Should We Protect and Sustain Wetlands?
To maintain the ecological and economic services of wetlands, we must maximize the preservation of remaining wetlands and the restoration of degraded wetlands.
How should we protect and sustain freshwater lakes, rivers, and fisheries?
Freshwater ecosystems are strongly affected by human activities on adjacent lands, and protecting these ecosystems must include protection of their watersheds.
What Should be our Priorities for Sustaining Aquatic Biodiversity?
Sustaining the world's aquatic biodiversity requires mapping it, protecting aquatic hotspots, creating large, fully protected marine reserves, protecting freshwater ecosystems, and carrying out ecological restoration of degraded coastal and inland wetlands.
Patterns of Marine Biodiversity:
Greatest biodiversity occurs in coral reefs, estuaries and the deep-ocean floor
Higher biodiversity along coasts than in open ocean
Higher biodiversity at the bottom of the ocean than on the surface
Coast habitat loss for development are 2-10x higher than tropical rainforests! :(
Sea level rise also threatens coastal habitats
Benthic habitats threatened by dredging and trawling
Dragging a funnel-shaped net held open at the neck along the ocean bottom, scraping up everything that lies on the ocean floor [to catch fishes and shellfish—especially cod, flounder, shrimp, and scallops] and often destroying bottom habitats. It's like clear-cutting the ocean floor.
Trawling --> MAJOR Habitat Destruction
These ocean floor communities could take decades or centuries to recover :((
"Bottom trawling is probably the largest human-caused disturbance to the biosphere."
An excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location. This technique is often used to keep waterways navigable.
Responsible for 2/3 of fish extinctions since 1990
Cost the US $16 million per HOUR!
Invasive Species: How do they get there?
Ship ballasts (where they store water to balance the ship)
Ship hulls (the main body of the vessel)
Deliberate introduction for sport
Alligators invading Long Island?
Invaders have Ravaged Lake Victoria (case study)
Lake Victoria = large lake in East Africa
invasive species: NILE PERCH:
the Nile perch is a fine food fish that can weigh more than 200 lbs.
Deliberately introduced in the 1950s&60s to stimulate the business of exporting fish from the lake to several European countries.
The population of the prolific Nile perch exploded, devoured the cichlids, and by 1986 had wiped out over 200 cichlid species. Reduced/eliminated many defenseless native fish species. Firewood depletion. Small scale fishers and vendors went out of business.
Played key role in MAJOR LOSS OF BIODIVERSITY in East Africa's Lake Victoria.
Algal Blooms and Water Hycinth
Invasive water hyacinths, supported by nutrient runoff, clogged a ferry terminal on the Kenyan part of Lake Victoria in 1997. Blocked sunlight, deprived fish
and plankton of oxygen, and reduced the diversity of important aquatic plant species.
Scientists reduced the problem at strategic locations by mechanical removal and by introducing two weevils for biological control of the hyacinth.
Similar to Algal Blooms (rapid increases or accumulations in the population of algae - opaque color)
Lake Wingra in Madison, WI
Lake Wingra has become eutrophic largely because of the introductions of invasive species, including the common carp, which now represents half of the fish biomass in the lake. Removal of carp in the experimental area shown here resulted in a dramatic improvement in the clarity of the water and subsequent regrowth of native plant species in shallow water.
What's the problem and what's being done (in terms of invasive species)?
Arrived in the Great Lakes via European ship ballast in 1986
It has become a major nuisance and a threat to commerce as well as to biodiversity in the Great Lakes: it outcompete native mussels and increases water clarity.
Native sponge may help control them
Pollution in Marine Ecosystems
Pollutants can be nutrients, toxins, "floatables"
In 2010 about 80% of the world's population was living along/near coasts
80% of the ocean pollution comes from terrestrial coastal activities (water runoff moves these pollutants from the land into the marine ecosystems)
% of the world's population living along/near coasts in 2010:
Combined Sewer Overflows (CSOs)
During wet weather, the system is overloaded due to excess stormwater --> Combine Sewer Overflow :( Majority of NYC is served by combined sewers that collect both sewage and runoff in a single pipe system.
- CSOs contribute nearly 27 billion gallons of untreated discharge to the city's waterways each year :(
These CSOs increase levels of bacteria, pathogens, solids, debris, and toxic pollutants to receiving waters.
They occur about once a week
The effects of CSOs in the city's waterways limit recreation, pose a threat to public health, and contribute to a chronic water quality problem.
Garbage patch in the Pacific Ocean
Ocean currents enable trash discarded in one country to land on the shores of another thousands of miles away
"The Great Pacific Garbage Patch" convergence zone
Climate Change's effects on Aquatic Biodiversity
Sea Level Rise - will affect coastal ecosystems (estuaries, wetlands, coral reefs)
Temperature Increase - coral can be very sensitive to warming
Overfishing - greatest threat to marine ecosystems, according to EPA
EPA considers this to be the greatest threat to marine ecosystems
Can lead to commercial and biological extinctions
Global fishprint (area of ocean needed to sustain fish consumption) 57% more than the sustainable yield
The area of ocean needed to sustain the fish consumption of an average person, a nation, or the world.
The global fishprint has become unsustainable.
All nations together are overfishing the world's global oceans taking 57% more than the sustainable yield. This means that we are harvesting more than half again as many wild fish as these species' populations can sustain in the long run. :(
Graph illustrating the collapse of the cod fishery in the northwest Atlantic off the Canadian coast
As industrialized fishing fleets vacuum up more and more of the world's available fish and shellfish, recovery times for severely depleted populations are increasing and can be 2 decades or more. In 1992, for example, off the coast of Newfoundland, Canada, the 500-year-old Atlantic cod fishery had collapsed and was closed to fishing. This put at least 20,000 fishers and fish processors out of work and severely damaged Newfoundland's economy. As the graph shows, this cod population has not recovered,
despite a total ban on fishing.
The collapse of the cod fishery in the northwest Atlantic off the Canadian coast. Beginning in the late 1950s, fishers used bottom trawlers to capture more of the stock, reflected in the sharp rise in this graph. This resulted in extreme overexploitation of the fishery, which began a steady fall throughout the 1970s, followed by a slight recovery in the 1980s and total collapse by 1992 when the site was closed to fishing. Canadian attempts to regulate fishing through a quota system had failed to stop the sharp decline. The fishery was reopened on a limited basis in 1998 but then closed indefinitely in 2003.
Major commercial fishing methods used to harvest various marine species (These methods have become so effective that many fish species have become commercially extinct):
These methods have become so effective that many fish species have become commercially extinct.
Fish farming in cage
Trawler fishing (Sonar at bottom of boat)
Drift-net fishing (Float/Buoy net) -> Fish caught by gills
Deep sea aquaculture cage
Long line fishing (lines with hooks)
What are some of the challenges to protecting Marine Biodiversity?
Population and need for marine resources is increasing so rapidly that it is difficult to monitor
Lack of visibility
Perception that marine resources are unlimited
What are some of the solutions to protecting Marine Biodiversity?
National and international laws and treaties
Economic incentives (tourism)
Marine sanctuaries (MPAs)
How to sustain fisheries?
(First, you need good estimates of the populations and growth rates to establish yield models)
- Regulate fish harvest
- Subsidies may encourage overfishing
- Consumer choices can help sustain fisheries
How can you protect wetlands?
Zoning Laws: Developing wetlands that are >3 acres requires a federal permit (this covers 6% of inland wetlands)
Mitigation Banking: Wetlands can only be destroyed if another wetland of equal area and same type is created (but at least half of the attempts to create new wetlands failed to replace lost ones, and most of the created wetlands did not provide the ecological functions of natural wetlands. Also, wetland creation projects often fail to meet the standards set for them and are not adequately monitored)
A concentration of a particular wild aquatic species suitable for commercial harvesting in a given ocean area or inland body of water
Commercial Extinction (a result of overfishing)
Occurs when it is no longer profitable to continue harvesting the affected species.
Overfishing usually results in only a temporary depletion of fish stocks,
as long as depleted areas and fisheries are allowed to recover. But as industrialized fishing fleets vacuum up more and more of the world's available fish and shellfish, recovery times for severely depleted populations are increasing and can be 2 decades or more. In 1992, for example, off the coast of Newfoundland, Canada, the 500-year-old Atlantic cod fishery had collapsed and was closed to fishing. This put at least 20,000 fishers and fish processors out of work and severely damaged Newfoundland's economy. As the graph shows, this cod population has not recovered, despite a total ban on fishing.
How can you protect freshwater ecosystems?
- HIPPCO applies to freshwater systems as well
- 40% of the world's rivers have been dammed or otherwise engineered (complex tradeoffs between energy, drinking water, irrigation, and species diversity)
TAKE A WATERSHED APPROACH: We can protect freshwater ecosystems by protecting Watersheds. To protect a stream or lake from excessive inputs of nutrients and pollutants, we must protect its watershed. We need an understanding of the land and water connections.
What should our priorities be in terms of protecting Marine ecosystems?
Mapping world's aquatic biodiversity
Identify hot spots
Create large and fully protected marine reserves
Protect and restore lakes
Worldwide restoration of coral reefs and wetlands