Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 18 Lecture Slides

Chapter 18 The Impacts of Human on the Marine Environment

Modification and Destruction of Habitats Most habitat destruction occurs close to shore (due to the greater number of humans nearby) Most habitat destruction occurs close to shore (due to the greater number of humans nearby) Much of this destruction results from unplanned or poorly planned development Much of this destruction results from unplanned or poorly planned development This destruction is more pronounced in developing countries, but it is not restricted to these areas This destruction is more pronounced in developing countries, but it is not restricted to these areas

Coral Reefs Approximately one-fourth of all coral reefs have already been lost or are at risk Approximately one-fourth of all coral reefs have already been lost or are at risk Pollution from sewage, sedimentation, and rising temperatures have caused some of this damage Pollution from sewage, sedimentation, and rising temperatures have caused some of this damage Corals are also lost due to collection for the aquarium trade and for sale as souvenirs Corals are also lost due to collection for the aquarium trade and for sale as souvenirs

Coral Reefs One-third of reef-building corals currently face extinction One-third of reef-building corals currently face extinction

Problems Caused by Trawling Trawl nets are a major threat to subtidal habitats Trawl nets are a major threat to subtidal habitats These nets, which drag along the bottom, cause resuspension of sediments which can kill suspension feeders These nets, which drag along the bottom, cause resuspension of sediments which can kill suspension feeders The trawls can also break off attached organisms The trawls can also break off attached organisms

Pollution Pollution is described as the human introduction of a substance that reduces the quality of the environment Pollution is described as the human introduction of a substance that reduces the quality of the environment Some pollutants are liberated by human activities such as the release of heavy metals from mining Some pollutants are liberated by human activities such as the release of heavy metals from mining Most pollutants come from land-based substances Most pollutants come from land-based substances

Sources of Pollution 1. Fertilizers 2. Sewage 3. Oil 4. Persistent toxic substances

Sources of Pollution Fertilizers Fertilizers –Land-based fertilizers wash into streams and rivers and are carried into coastal waters –This influx of nutrients causes phytoplankton numbers to rise rapidly (called a “bloom”) resulting in eutrophification –These blooms can cause several problems including reducing the amount of light available to organisms attached to the bottom such as seagrasses and corals

Sources of Pollution Fertilizers Fertilizers –Other problems with these blooms occur after the phytoplankton die –As cells die and drop to the bottom, the influx of massive amounts of organic matter means decomposing bacteria begin to work –As a result of this breakdown, oxygen is consumed and anoxic conditions may occur

Sources of Pollution

Sewage Sewage –Domestic sewage comes from homes and city buildings as well as stormwater runoff –Industrial sewage comes from factories, etc. and may contain a variety of substances –This sewage may contain disease-causing organisms –It may also contain heavy metals or other toxic substances even if treated

Sources of Pollution

Oil Oil –Organisms can accumulate components, many of which are toxic –These components can affect reproduction, growth, development and behavior –Organisms may also die of their feathers or fur is coated with oil (remember the Exxon Valdez and other accidents) –Estuarine organisms, seagrasses and corals are also at risk if coated with oil

Sources of Pollution

Persistent Toxic Substances Persistent Toxic Substances –Examples are chlorinated hydrocarbons and polychlorinated biphenyls (PCB’s) and heavy metals –In the case of chlorinated hydrocarbons, these substances are dissolved in the fats of organisms and are passed from prey to predator –As predators eat more prey, they continue to accumulate in their tissues (known as biological magnification)

Sources of Pollution Some fishes may not be safe to eat due to these levels Some fishes may not be safe to eat due to these levels Fortunately, the levels of chlorinated hydrocarbons is not as high as it once was Fortunately, the levels of chlorinated hydrocarbons is not as high as it once was The levels of PCBs and heavy metals in the ocean continues to be a problem as well The levels of PCBs and heavy metals in the ocean continues to be a problem as well

Other Dangers to the Marine Environment Solid wastes Solid wastes Thermal pollution Thermal pollution Saline brines from desalination plants Saline brines from desalination plants

Threatened and Endangered Species Organisms normally adapt to changing conditions through a process known as natural selection Organisms normally adapt to changing conditions through a process known as natural selection If they cannot adapt, they go extinct If they cannot adapt, they go extinct Human-induced extinctions can be called exterminations Human-induced extinctions can be called exterminations

Threatened and Endangered Species Threatened status – numbers of a species are low and a species is in danger of becoming endangered Threatened status – numbers of a species are low and a species is in danger of becoming endangered Endangered status – species is in immediate danger of extinction Endangered status – species is in immediate danger of extinction

Threatened and Endangered Species

Example of an Extermination Example of an Extermination Stellar’s sea cow Stellar’s sea cow Extermination by overfishing Extermination by overfishing The species became known to science in 1741; the last known live individual was taken in 1768 The species became known to science in 1741; the last known live individual was taken in 1768

Threatened and Endangered Species Examples of other species imperiled today: Examples of other species imperiled today: –Whales – due to overfishing –Giant clams – for food and shells (collectors) –Cowries and cone shells – for shells (collectors) –Sharks – due to overfishing –Sea turtles – for food, jewelry, shells and other purposes

Conservation Methods Used to Protect Marine Organisms and Habitats Efforts to keep development at sustainable levels Efforts to keep development at sustainable levels These are on local, national and international efforts These are on local, national and international efforts Fisheries management with EEZ’s Fisheries management with EEZ’s Marine protected areas Marine protected areas Habitat restoration Habitat restoration Artificial reefs Artificial reefs