Environmental Biology: The Effects of Pollution in the Ocean
The oceans are being contaminated by pollution caused by oil spills, tanker discharges, untreated municipal wastes and agrochemical residues. Pollution is known to have destabilized many coastal ecosystems and is believed to be responsible for the decline in phytoplankton and consumable shellfish which usually thrive further out to sea. Medical wastes, beach visitors' garbage, waterfront businesses account for most of the toxic and most dangerous pollutants that lurk below the surface of the ocean. Oil spills and medical wastes only play a small part in ocean pollution (Energy Intelligence Group, 2002). Plants and factories spew over thirty-two billion gallons of poisonous chemicals and sewage into the sea every day. The Commerce Department's National Oceanic and Atmospheric Administration (2000) states that eighty percent of pollution to the marine environment comes from land-based sources, such as runoff pollution. Runoff pollution includes many small sources, like septic tanks, cars, trucks and boats, plus larger sources, such as farms, ranches and forest areas. Oceanographers contribute the loss of fish production and the choking of the coastal zone to the waste that is thrown into the ocean waters.
Pesticide residues affect the sea life habitats within the ocean. In many areas, consumers have been warned not to eat much shellfish because of the unacceptable levels of bacteria, viruses and toxic chemicals they contain. Ingestion of this food is not healthy for the person who consumes it.
An ocean organism's internal environment is highly influenced by many external factors. Many marine invertebrates are conformers and have the ability to thrive around the world. They have no need to control their internal environment since the external environment is fairly constant in terms of temperature, oxygen tension, and nutrients. However, with the threat of pollution, the marine invertebrates ability to live within the dirtied and toxic waters are compromised, therefore, resulting in fewer numbers for reproduction, production and harvest.
Industries in the United States discharge pollutants that include many toxic chemicals. Industries discharge much chemical waste directly into natural bodies of water. The burning of coal, oil, and other fuels by power plants, factories, and motor vehicles also release sulfur and nitrogen oxides into the air. These pollutants cause acid rain, which enters streams and lakes. High levels of mercury have been found in fish far from industrial areas. The main sources of the mercury appear to be emissions to the atmosphere from coal-fired boilers, municipal incinerators, and smelters. Some industries pollute water in yet another way. They use large quantities of water to cool certain equipment. Heat from the equipment makes the water hot. The industries then discharge the hot water into rivers and lakes, heating those bodies of water, thus causing thermal pollution.
The use of pesticides, herbicides and other poisons with agriculture is helpful for man to produce affordable food, but it also deprives people of marine food sources (Boukhari, 1998). Excessive use of these chemicals allows the product to wash off the land into rivers and reservoirs, thus affecting the growth and development of ocean life. This especially applies to crustacean larvae and young creatures. These chemicals also modify the structure of phytoplankton communities and disturb photosynthesis. The combination of phosphates and nitrates within the fertilizers also create large outbreaks of unicellular algae. These toxins remain within the organism and progress up the food chain into the bodies of their predators. This is harmful to the people who consume them as a food source. Organic pollutants can become increasingly concentrated as they move up food chain; a predator eats the amount accumulating as each carrier. Marine mammals top the oceans' predatory pyramids. Pesticides form a reservoir of poisons when they combine with fatty parts such as the blubber and liver of pinniped and cetacean bodies.
A severe problem currently found in water pollution is the need to modernize water treatment systems.
This is necessary in order to remove pharmaceutical waste that is destabilizing the food chain and polluting the environment. Keith Solomon (Society of Chemical Industry, 2002), director of the department of toxicology and professor in the department of environmental biology at the University of Guelph. Ontario, Canada feels this need should be made a high priority when looking at the overall picture to clean up the environment.
Human excrement must be treated in a more sophisticated manner to eliminate the mixture of pharmaceuticals such as Prozac and antibiotics that are finding their way into water. This combination is severely having dramatic effects on Daphnia, an important aquatic organism in the food chain. Pharmaceuticals may damage the environment, but it is unlikely their use will be reduced, as the population increases and ages. "If these compounds are causing adverse effects in the environment, the most appropriate approach would be to reduce exposures by sewage treatment," said Solomon (Society of Chemical Industry, 2002).
While some poison is eliminated, and can be metabolized, both mean danger to the environment. Metabolites are often more toxic and longer lasting than their original forms, which can stay in the environment up to fifty years. This process is thought to add to the migratory nature of many marine mammals and the slow buildup of toxins in large-bodied, long-lived top predators.
The use of these pesticides also creates problematic situations where these outbreaks are the danger of asphyxiation or lack of oxygen produced within the waters. Bacteria thrive on nutrients from dead phytoplankton and eventually use up the water's oxygen. Soon, when anoxia sets in, and only animals that don't require oxygen manage to thrive. This problem causes extreme dangers for ocean life.
Low levels of oxygen now are the cause of large numbers of fish deaths than any other single agent, including oil spills, and it ranks as a leading threat to commercial fisheries and the marine environment. Hypoxic water has less than two milliliters of oxygen per liter of water. It can occur seasonally or sporadically, or it can persist for a year or more (Adler, 1996). The tissues and body fluids of the marine animals are made more acidic as a result of the levels of carbon dioxide contained within the water.
Some marine life has the ability to switch from aerobic to anaerobic metabolism. This requires them to make use of different chemicals in their bodies to produce energy when threatened with low levels of oxygen while also making use of less energy. One type of sea life, the priapulid worm, can survive for ninety days by switching to anaerobic metabolism. About one third of atmospheric pollutants directly fall into the sea or with rainfall (Boukhari, 1998).
Harmful Algal Blooms or HABS are the growth and accumulation of microscopic marine plants that cause "red tides." These blooms are extremely toxic; both to the marine life feeding upon them and to people who eat contaminated shellfish. Over the past decade, the number of such single-celled algal species has soared from twenty-two to fifty-five around the world. Outbreaks once found only around certain coastal areas of Europe and the United States have spread to Asia and Latin America. Some of this is naturally occurring, as ocean currents deposit seed populations. Algie species are also transferred by the water blasted from ships, and appear to flourish when pollutants add excessive nutrients to the water.
More problems occur with the addition of pollutants to the water. The decay process uses oxygen, and with the use of more oxygen needed for this process, it eliminates what might be left to support living things in the water. Game fish such as salmon, trout, and whitefish cannot live with the reduced oxygen situation and will die. Fish that need less oxygen, such as carp and catfish, will replace them. If all the oxygen in a body of water were to be used up, most forms of life in the water would die.
The ocean receives two billion tons of carbon dioxide annually. The ocean creates a "recycling machine" for gases that are present in the atmosphere, however, with the problem of toxins in the ocean, "scientists wonder whether it will be able to adapt to the global warming induced by the greenhouse gases produced by human activities, without disturbing its equilibrium and its circulation." The waters are in danger of undergoing an extreme evolution if containment of dissolved oxygen is available to living marine organisms, especially of slow-growing demersal fish species.
Biodiversity is declining, and we must begin to implement a way to save this environment.
Another threat caused by ocean pollution is the ability of artificial organic chemicals to induce abortions in mammals, suppress their immune systems, and attack the normal functioning of vital organs exist in the tissues of sea creatures up and down food webs from the Arctic to the Antarctic. Evidence continues to mount implicating these compounds in marine mammal die-offs in Atlantic and Mediterranean coastal waters. Though few will claim a direct cause-and-effect relationship, many researchers see a chain of circumstantial factors linking chemical pollutants with animals' increased vulnerability to…