Marine Biology Essay, Research Paper

A major source of coastal pollutants, human sewage fouls bays and beaches with

both toxic and nontoxic pollutants. Although billions of dollars have been

invested in sewage treatment plants to treat wastewater, new and growing coastal

communities have increased the amount of discharge into oceans and estuaries.

The United States Office of Technology Assessment has identified thirteen

hundred major industries and six hundred municipal wastewater treatment plants

that discharge into coastal waters of the United States. Many toxic substances

enter the sea through the sewer systems, but others originate as industrial

discharges. For many toxic substances, we do not yet know how to determine their

extent or fate in the marine environment or to evaluate their effects on marine

life. Some of the better-known trace metals and toxic chemicals include mercury,

copper, lead, and chlorinated hydrocarbons. Chlorinated hydrocarbons, synthetic

chlorine-containing compounds, are created for use as pesticides or are

by-products of the manufacture of plastics. Oil is a very dangerous thing when

it comes to oil spills into the ocean. These catastrophic oil spills engender a

concern for the marine environment as no invisible containment can. Spilled oil

floats on seawater and provides a constant reminder of its presence until it is

washed ashore, sinks, or evaporates. Large volumes of oil suffocate benthic

organisms by clogging their gills and filtering structures or fouling their

digestive tracts. Marine birds and mammals suffer heavily as their feathers or

fur become oil soaked and matter, and they lose insulation and buoyancy. Until

recently, marine debris was considered to be of minor importance when compared

to other pollutants. Problems caused by marine debris, however may rival or

exceed those resulting from some better known pollutants, including oil. By

definition, marine debris is any manufactured object discarded in the marine

environment. When dumped, it may sink to the sea floor, remain suspended at

mid-depths, or float at the surface and eventually be carried ashore by winds

and waves. Plastics constitute as great an environmental threat as all the other

kinds of debris, combined. Although plastics may break up into smaller pieces,

they degrade much more slowly than most other kinds of debris, and most plastics

float. Concentrations of plastics tend to be highest in the Northern Hemisphere,

where vessel traffic is the heaviest, where most plastics manufacturers and

fabricators are located, and where more intensive recreational use is made of

beaches and coastal waters. Hopefully, as we approach the twenty-first century,

we can learn to leave some old and wasteful habits behind. It will not be easy

or simple, but each one of us must develop a sense of stewardship toward the

world ocean and its resources that is reflected in our personal as well as our

political decisions.