Chapter 11
Sustaining Aquatic Biodiversity
Key Questions and Concepts
11-1 What are the major threats to aquatic biodiversity?
CORE CASE STUDY: The introduction of the large predatory Nile __________ into Lake Victoria in East
Africa has led to the _____________________ of some 200 cichlid species. The lake was once home to about
500 ________________ species. In a __________ time, many have been driven to extinction, and many more
are currently at risk. The introduction of the Nile perch served to satisfy a market in ____________, but has
had ____________________ consequences, such as changes in the local economy and widespread
________________________.
We know very little about the earth’s aquatic biodiversity because there has been so little exploration of the
water on this “__________ planet.”
A. Three patterns of marine biodiversity are:
1. The greatest marine biodiversity occurs in coral reefs, ________________, and on the deep-sea ocean
floor.
2. Biodiversity is higher near the coasts because of great variety of producers, habitats, and
_______________ areas.
3. Biodiversity is higher in the ____________ region than in the surface region of the ocean.
B. The greatest threat to the biodiversity of oceans is loss and degradation of ________________.
1. Coral reefs, _________________ forests, and coastal wetlands are under great ________________
from human activities.
2. ________________ and ________________ are major threats to sea bottom habitats.
3. Dams and excessive water _________________________ are destroying freshwater habitats.
C. Harmful _________________ species increasingly threaten marine biodiversity.
D. By 2020, ____% of the world’s population will live near coasts. Population growth and
__________________ have drastic effects on ocean systems.
1. Pollutants such as nitrogen from ____________________ can cause algal ____________ and
eutrophication.
2. __________ pollutants can kill some aquatic life forms.
SCIENCE FOCUS: Lake Wingra in Wisconsin receives excessive ___________________ from runoff and
is populated by invasive species, including ________ and purple loosestrife. The carp devour the
__________ that would normally stabilize ___________________ on the lake bottom. Scientific
experiments that involved excluding carp from a study area showed that algae ____________________ and
the lake water became noticeably _______________. There is now an effort to _____________ the carp
from the rest of the lake to alleviate the _____________ of this invasive species.
E. Climate ____________ threatens aquatic biodiversity and ecosystems services.
F. Overfishing can have drastic effects on biodiversity.
1. Modern ___________________ fishing can deplete 80% of target fish species in just 10–____ years.
2. Overfishing can lead to ____________________ extinction, which occurs when it is no longer
___________________ to continue fishing the affected species.
3. Nearly one-__________ of annual fish catch consists of ______________—non-target species that are
thrown __________________.
4. Marine and freshwater fishes are threatened with ____________________ by human activities more
than any other group of species.
SCIENCE FOCUS: __________________ provide important ecological services. They reduce the
impacts of ____________ and rising sea levels. Due to coastal _____________________ in Indonesia,
about ____% of that nation’s mangroves have been degraded or _________________. There are now
efforts to protect these areas. The economic __________________ and ecological services provided by
mangroves should be considered in all coastal development __________.
CASE STUDY: Industrial fishing __________________ the global fishing industry. 75% of the
world’s fisheries are fished _________________________. ______________ fishing extracts fish and
shellfish from the ocean floor. Purse-__________ fishing is used to catch surface dwelling species.
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____________________ strings out thousands of baited hooks as much as ____ miles long. Finally,
__________ netting involves massive nets up to 2 miles long that can lead to overfishing. In 1992, the
UN limited the _______ of driftnets that could be used in international waters, but compliance is
_____________________.
11-2 How can we protect and sustain marine biodiversity?
A. Protecting marine biodiversity is difficult because it is difficult to ______________ the impact of the
human ecological footprint, oceans are unseen by most people, oceans are often thought to be ____________________________ resources, and most of the ocean area lies outside of the
_________________________ of any nation.
CASE STUDY: Overharvesting of whale species has driven some __________________________
valuable species to the brink of extinction. ________ whales were once numerous, but today only a small
portion of their original population remains. Despite ____________________, it is uncertain whether their
population will make a comeback. Several _______________ continue to harvest whales, and are
attempting to overthrow ________ on commercial whaling. At the same time, some communities have
prospered by offering whale ________________ excursions to tourists.
B. Biodiversity can be valuable to local communities that develop eco-________________ markets.
CASE STUDY: Six of the seven species of marine ______________ are endangered. ________________
turtles are being heavily impacted by human activities. _______________ practices, pollution, and climate
change all threaten their survival. However, there has been progress. Some local communities are reducing
their impacts on _______________ where turtles lay their eggs, Turtle _________________ Devices are
now required on _________________ by the U.S. government, and some communities are focusing on the
__________________ advantages of protecting these species
C. A country’s offshore fishing zone extends 370 ______________________ from its shores.
1. Ocean areas beyond these Exclusive Economic Zones, called the _______ seas, are difficult to monitor.
2. The World ____________________ Union helped establish a global system of marine _____________
areas (MPAs).
3. There are about 4,000 MPAs, almost ______ in U.S. waters; however, most MPAs __________
ecologically harmful activities like trawling, ________________, and resource extraction.
D. Scientists are advocating an _____________________ approach to sustaining marine biodiversity.
1. This would entail a ______________ of protected marine reserves, closed to ____________________
activities.
2. Studies show that within as few as ___ years after establishing a reserve the fish are larger,
____________________more often, and are in greater ______________ than previously.
3. Less that __% of the world’s ocean area is closed to fishing in marine _________________.
E. ____________________ coastal management is a ___________________-based effort to develop and use
coastal resources more sustainably.
1. The idea is to find ________-effective, _________________ solutions to preserve biodiversity while
meeting economic and ____________ needs.
11-3 How should we ______________ and sustain marine fisheries?
A. One way to prevent _______________________ is to develop better ways to protect fish populations. The
maximum sustained __________ mathematical model is used, but indications are that it has hastened the
_________________ of most commercially valuable stocks for several reasons.
B. O_____________ sustained yield is a concept that takes into account interactions with other ____________
and allows more room for ___________. Another approach is multi-_______________ management of a
number of interacting species, which accounts for ____________________ and predator-prey interactions.
1. There has been ________________ management of several large marine systems, such as the
_______________________ Sea.
2. Many fisheries scientists and environmentalists are interested in using the ________________________
principle for management of fisheries and marine systems.
C. Some fishing communities regulate fish harvests on their ______ and others work with the government to
_______________ them. Influx of large modern fishing boats and ____________ has weakened the ability
to regulate and sustain __________ fisheries. Many community management systems are now ____________________, where community and government work together to manage fisheries.
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Sustaining Aquatic Biodiversity
1. Central government sets ____________ for various species and _____________ the quotas among
communities.
2. Government may also limit fishing ______________ and regulate ________ to be used.
3. Each community then __________________ its quota among members.
D. Government __________________ that are intended to keep businesses afloat can encourage
__________________________.
E. Individual _______________ rights (ITRs) are assigned to each fisherman, and these can then be bought,
sold, or ____________ like private property. This has resulted in some ___________________ of
overfishing, but it is hard to _______________, and wasteful ______________ has not been reduced.
F. Problems with the ITQ system are:
1. It transfers public ownership to _______________ fishers, but still makes the public responsible for
cost of management and _____________________.
2. Small fishing vessels and companies may be ________________ out if they can’t ____________ to buy
ITQs from others.
3. Fishing quotas are often set too ________, so they leave 10–50% of the estimated MSY as a
____________ to protect the fishery from decline.
G. Individuals can help sustain aquatic diversity by demanding sustainably harvested ______________.
1. ________________ seafood would inform consumers.
11-4 How should we protect and sustain wetlands?
A. Coastal and inland wetlands are important _____________________ of aquatic biodiversity; they provide
ecological and economic __________________.
1. Despite their value, the U.S. has lost more than ________ of its coastal and inland wetlands since 1900.
2. Wetland loss in the U.S. will get worse as global warming leads to ____________ sea levels, which will
put many coastal wetlands ___________ water.
B. In the U.S., a federal permit is required to fill or deposit ____________ material into many wetlands.
1. The U.S. federal policy is a ________ net loss goal; ___________________ banking allows destruction
of some wetlands as long as the same type of wetland is ______________ elsewhere.
CASE STUDY: An ambitious ____________________ project is trying to undo the human damage in
South ______________’s Everglades. The natural Everglades is ________ its original size and is drying
out, leaving it vulnerable to ________ and invasion by nonnative species. Everglades National Park was set
up in the lower part of the Everglades, but __________ didn’t flow into it and human activity caused
disturbances. ____________ percent of the wading __________ are gone and other vertebrates are reduced
in number by ___________%. Florida Bay has become _______________ and warmer due to lack of water
flow from the Everglades and the Kissimmee ___________. Loss of water flow and input from _________
fields and cities has caused large ___________ blooms on the bay.
These blooms threaten coral ___________ and hinder diving, fishing, and the tourist ________________ of
the bay and the Florida Keys. The U.S. Army Corp of __________________ has begun a restoration project
funded by the state and the _______________ government to restore the __________________ river and
_________ of water to the Everglades. It has several ambitious goals, which include restoring
_______________ flow of more than half of the Kissimmee River, removing 250 miles of canals and
_____________ south of Lake Okeechobee, buying 93 square miles of farmland and allowing it to
___________ to create artificial marshes, creating a _______________ of artificial marshes, creating 18 large
_____________________ to ensure water for south Florida’s present and future ____________________ and
the lower Everglades, and building new canals, reservoirs, and pumping stations to capture and ____________
to the Everglades ____% of the water flowing out to sea.
11-5 How can we protect and sustain freshwater lakes, rivers, and fisheries?
A. There are many threats to freshwater ecosystems, including habitat _______________________, invasive
species, and pollution.
CASE STUDY: Invasions by ____________________ species have upset the ecological functioning of the
Great Lakes for decades, with more invaders coming. At least ______ nonnative species have invaded the
Great Lakes since the 1920s. Measures have been taken to control a number of these species. Sea
_________________ are one of the biggest threats and have depleted a number of the ___________ fish
species in the lakes. Zebra _______________ were brought into the lakes in ______________ and have
become very aggressive pests since they have no known natural _______________. They have
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B.
C.
D.
E.
F.
G.
________________ native mussel species, clogged __________ and piers, fouled beaches, and have
___________ to other parts of the U.S. _____________ mussels invaded the Great Lakes in 1991 and
Asian ________ may be the next invader.
Rivers/streams are important ecological and economic resources, but they can be degraded by overfishing,
pollution, dams, and water _____________________.
The _____________________ River has been altered by 119 dams and withdrawal of water for
_____________________.
To protect rivers and lakes from excess pollutants, ____________________ need to be protected.
The National Wild and _____________ Rivers Act was passed in 1968 to protect rivers and river segments
with outstanding scenic, recreational, geological, wildlife, historical, or ________________ values.
Congress established a three-tiered _________________________ scheme:
1. ________ rivers are relatively inaccessible; they are not permitted to be widened, _________________,
dredged, filled or dammed.
2. ____________ rivers are free from dams, mostly undeveloped, of great scenic value, and accessible in
some places by ___________.
3. _______________________ rivers are readily accessible by roads and may have some ________ or
development along their shores.
4. Only 0.__% of the 3.5 million miles of rivers are protected under the act.
Sustainable _____________________ of freshwater fish involves encouraging ______________________
of commercial/sport fish species, prevents overfishing, and reduces or ______________________ less
desirable fish populations.
11-6 What should our _____________________ be for sustaining biodiversity and ecosystem services?
A. There is evidence that the harmful effects of human activities on biodiversity can be _______________
over the next two decades.
1. This must entail an ecosystem _________________ to protecting biodiversity.
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Sustaining Aquatic Biodiversity