A Perspective on Marine Pollution

With a large and growing portion of the world’s population living only a short distance from coasts, the potential for human impact is easily seen. Rivers and terrestrial run off are thought to transport perhaps 80 percent of the materials that are typically introduced into the coastal environment and which can be characterized as pollutants. Commonly included in this category are materials like plastics, toxins such as DDT, PCBs, PAHs, heavy metals, and petroleum. These materials, some of which have limited water solubility, are able to be incorporated in lower trophic levels and will be magnified up the food chain. More recently, with an increasing awareness of more subtle, nonpoint source introduction, inorganic nitrogen from wastewater or fertilizers, or endocrine disrupting materials has been documented. Release of excess nitrogen into coastal environments is associated with terrestrial practices utilizing the inorganic fertilizers used in agriculture and clearly causes nearshore eutrophication. These excesses are capable of establishing water columns that are categorized as “dead zones” owing to the near absence of oxygen in the water. The impacts of future coastal seabed mining are only beginning to be understood. While introduction of significant amounts of petroleum hydrocarbons through accidents still occurs, it has been declining; the greatest amount of petroleum contaminants released into marine environments is associated with nonpoint sources from rivers and the land, especially urban locations. Macroscale plastics are increasingly disposed of into the coastal environment and affect all trophic levels of the ecosystem. It is anticipated that within the next 25 years the amount of discarded plastic may exceed the amount of fish in the ocean. Only recently has the sheer volume of microplastic debris been given the increased awareness of its potential impact. The possibility also exists of even greater influence on coastal areas in locations like the High Arctic, a result of oil exploration and transport in locations with diminished ice cover. Together, heightened levels of pollutants will reduce coastal biodiversity and productivity and result in a reduction of food resources. Information and public awareness of the sources, and detrimental effects of these materials, has to be understood if this problem can be coherently addressed.