Chapter 12 Review Questions
1. Ecological problems: 1.large increase in the population of the Nile perch. This huge predatory fish will reduce or eliminate many defenseless native fish species. It puts small-scale fishers ad fish vendors out of business, and local forests were depleted for firewood because of the perch’s oily flesh that must be preserved by smoking. 2. lake began experienceng alfal blooms because of nutrient runoff from surrounding farms, deforested land, untreated sewage, and declines in the populations of the algae eating cichlids. 3. The nutrient-rich lake has been invaded by the water hyacinth. 4. Nile perch population is decreasing because it severely reduced its own food supply of smaller fishes.
2. 1. greatest marine biodiversity occurs in coral reefs, estuaries, and the deep ocean floor. 2. biodiversity is higher near coasts than in the open sea because of the greater variety of producers and habitats in coastal areas. 2. Biodiversity is higher in the bottom region of the ocean than in the surface region.
3. It helps us stay alive and it helps support our economies, marine systems provide important ecological and economical service activities.
4. Habitat loss and degradation, the greatest threat to the biodiversity of the worlds oceans and freshwater system..Dams currently hold three to six times the amount that flows into natural rivers and humans take twice as much water from each year from rivers and lakes. This destroys aquatic habitats and water flows and disrupts freshwater diversity.Population growth and overfishing are other problems which harm aquatic zones.
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6. the coastal population growth will add to the intense pressure on the worlds coastal zones. in 2004, the UNEP estimated that 80% of the oceans pollution comes from land-based coastal activities. So humans have doubled the flow of nitrogen, mostly from nitrate fertilizers, into the oceans since 1860, and the 2005 Millennium Ecosystem Assessment estiates this flow will increase by another two-thirds by 2050
7. Overfishing has affected the populations of many marine and freshwater aquatic species, because when they over fish the fish cant reproduced fast enough
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11. Four Factors that threaten the florida Manatee are that they usually die from habitat loss, cold weather, getting caught in fishing lines and nets, and when they’re slashed by propellers.
12. Toothed whales bite and chew their food and feed mostly on squid,octopus, and other marine animals.Toothed whales include Sperm whale and squid, Killer Whale, Narwhal, and a Bottlenose dolphin. Baleen whales use plates made of baleen, or whalebone that hang down from their upper jaw filter plankton from the seawater,especially tiny shrimplike krill. Baleen Whales include Blue,gray,humpback,and finback whales.
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16. a. The traditional approach to the estimation and management of fish populations is called maximum sustained yield, and it is used to project the maximum number of fish that can be harvested annually from a fish stock without causing population drop.
16. b. In recent years, some fishery biologists and managers have begun using the optimum sustained yield. It attempts to take into account interactions with other species and to provide more room for error.
16. c. Another approach is multispecies management of a number of interacting species ,
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18.Describe the regulation of fish harvests through comanagement.
19.Describe the status of wetland protection in the United States and list six ways to improve wetlands protection.
20.Describe the ecological and water supply problems of south Florida’s Everglades and efforts to deal with these problems.
21. The Quagga Mussel,sea lamprey,larvae of zebra mussel, and the Asian corp, that all invaded the Great Lakes, are very destructive and cost Canada and the United States millions of dollars .
22. The effort that has been made is the $3 billion that has been spent to help save the salmon although it hasn’t been effective.
