Hobbies And Interests
Oil Spills
The oil from a spill bobs atop the surface of the ocean and soaks marine birds' feathers, causing breathing difficulties, impeding mobility and subjecting the birds to the cold. Ingested, the oil acts as a poison to their organs. Fish and shelled creatures contaminated with oil become inedible to consumers, disrupting local food chains. Oil spills carried by currents lap onto shores, coating shorelines with an unattractive black sheen. Cleanup can include leaving the oil for nature to disintegrate, gather as much of the oil as possible for disposal and breaking down the oil into less harmful substances.
Pollution
Biologists and conservationists consider a limited amount of ocean pollution to be natural. The ocean possesses an amazing ability for dispersing and dissolving pollutants; only when pollution becomes concentrated does the ocean suffer. To illustrate, years after the United States tested a hydrogen bomb on the Bikini Islands, the fruit and vegetation remain radioactive and inedible; however, people can safely fish in the waters surrounding the islands. When organisms higher up on the food chain consume contaminated prey, the concentration of pollutants may reach toxic levels in their bodies in a process called "bioaccumulation." Ocean pollutants include mercury, pesticides, plastic products, sewage and waste products.
Carbon Dioxide and Global Warming
Carbon dioxide constitutes one of the gases in the atmosphere that raises the global temperature. The warmer oceans slow the growth of phytoplankton -- tiny marine organisms able to produce their own food from sunlight. Less phytoplankton thus become available for subsequent levels in the food chain, and marine organisms such as fish begin to starve.
Carbon dioxide also combines with seawater to make carbonic acid, adding acidity to the water. This increased acidity depletes levels of calcium carbonate, a substance that shelled animals need to build their protective coverings. Fish may develop a condition called acidosis, an accumulation of carbonic acid in the fluids of the body; acidosis compromises fish immune systems and contributes to reproductive abnormalities.
Deterioration of the Coral Reefs
Coral reefs, which are very sensitive to changes in their environments, provide habitats for numerous ocean organisms and act as barriers against large waves. Although these reefs account for a mere 0.2 percent of the oceans, they contain 25 percent of the oceans' species. Corals, organisms that produce hard, calcium-carbonate shells around themselves, attach to island parts under water. When these creatures die, their shells remain, and newer corals attach to their remains. An algae species called zooxanthellae live within the soft coral bodies, producing food for both organisms. Warm waters kill zooxanthellae, depriving corals of their greenish color and nutrients; this "coral bleaching" also destroys the coral. The increase in carbon dioxide drains the water of the calcium carbonate used by the corals to manufacture their rigid shells.
Biodiversity Threat
Through overfishing, man has become the main culprit to the loss of ocean species. Fishermen deplete the oceans of certain types of fish and edible organisms, sometimes with utter disregard for the ecosystem or government regulations. The Food and Agriculture Association notes that 70 percent of all fish are threatened with extinction; some species such as cod and flounder have been reduced by 95 percent. With the decline in their food sources, animals that feed on fish go hungry.