Potential Hazards and Aquatic Ecosystems

An aquatic ecosystem is an interdependent community of plants, animals and organisms located under water. Found in both marine and freshwater regions, aquatic ecosystems provide many valuable functions, such as nutrient recycling, water regeneration and providing habitats for wildlife. The health of an aquatic ecosystem depends on a careful balance of species and resources, and as a result, they are highly vulnerable to potential man-made and environmental hazards.

Overfishing

• Overfishing poses a grave hazard to aquatic ecosystems. The environmental organization Greenpeace estimates that as of 2011 more than 70 percent of the world's fisheries are either exploited or significantly depleted. Overfishing disrupts the balance of species, and causes negative changes to fish feeding and reproductive habits. One consequence of human appetites for particular fish is a massive drop off in the populations of larger species, such as tuna, swordfish and marlin, and a subsequent rise in the number of plankton-eating fish. Globally there has been a rise in the number of jellyfish in the seas. As traditional predators die off, their populations flourish.

Pesticides

• Chemical runoff and contamination from agricultural production poses a serious hazard to aquatic ecosystems. Pesticides contain substances harmful to plant and animal life, and can cause neurological and reproductive harm, as well as alter the pH levels of sensitive climates. Researchers from Virginia State University estimate that the U.S. uses more than one billion pounds of pesticides per year, much of which finds its way into water sources. They further maintain that pesticides are responsible for mass kill offs among thousands of species, including not only fish, but frogs, turtles and water birds.

Acid Rain

• Acid rain is caused when the combustion of chemicals and fossil fuels produces harmful particulate matter that returns to the earth in the form of precipitation. According to the Environmental Protection Agency, acid rain can devastate aquatic ecosystems by changing water pH levels and also introducing toxic chemicals into underwater environments. The agency describes acid rain as causing "a cascade of effects that harm or kill individual fish, reduce fish population numbers, completely eliminate fish species from a water body and decrease biodiversity."

Global Warming

• Perhaps the largest hazard to aquatic ecosystems are the environmental effects of man-made global warming. Global warming elevates the temperature of the oceans, and also causes altered weather patterns that bring severe storms to some regions and drought to others. The resulting changes in temperature along with drought and flooding damages the balance of aquatic life and threatens the viability of sensitive species. A 2002 report from the Pew Center on Global Change cautions that critical coastal systems, such as wetlands, marshes and coral reefs, are the most severely affected. These ecosystems are among the most bio-diverse on the planet, and their deterioration impacts the human populations who use them for food and recreation.