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University of Rhode Island — Marine Affairs
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Oil Spills and other Marine Pollutants
Marine Oil Spill

Exxon Valdez oil spill

A marine oil spill is the inadvertent release of crude oil (an unrefined liquid petroleum hydrocarbon) into the marine environment due to human intervention. Environmental disasters often follow significant marine oil spills. The following spills are the largest in American history:

  • March 24, 1989, the Exxon Valdez oil tanker struck Bligh Reef, spilling more than 11 million gallons of crude oil into Prince William Sound, Alaska. The environmental impacts were enormous, cleanup efforts were slow and inadequate, and the effects of the spill are still felt along the coast of Alaska.
  • April 20, 2010, the Deepwater Horizon, a deep sea oil drilling platform, exploded and released 204 million gallons of oil into the Gulf of Mexico. The spill impacted numerous habitats in the Gulf, affecting many marine organisms, the fishing industry, beaches, and the tourism industry in the area.

Damage to these delicate marine ecosystems, including both flora (plants) and fauna (animals), was profound in both spills, and the effects continue to this day. Marine biologists are involved in the cleanup of the spill and care for the sea life affected. After the Deepwater Horizon spill the Minerals Management Service, the government agency responsible for ensuring the safety of such rigs, was restructured and became the Bureau of Ocean Energy Management (BOEM) and the Bureau of Safety and Environmental Enforcement (BSEE). This restructuring should provide for more thorough oversight of such drilling operations.

Nutrient Loading, Dead Zones, and Harmful Algal Blooms

Stormwater overflow pipe and associated algal bloom

Nutrients are substances needed for growth. In the absence of nutrients, plants will stop growing and organisms higher up in the food chain will not have enough to eat to survive. Due to human impact, the nutrient cycle has been disrupted. Artificial nutrients (fertilizers produced by the chemical industry and phosphates used in cleaning products), along with nutrients resulting from burning fossil fuels, have substantially increased the quantity of nutrients on Earth. Due to the spatial difference between agricultural land and food consumption in cities, the distribution of nutrients is also disrupted.

Eventually most nutrients (mainly phosphorus and nitrogen) end up at "the end of the line" - in aquatic ecosystems. Loading aquatic ecosystems with these nutrients is called nutrient loading or eutrophication. Eutrophication causes uncontrolled reproduction of algae, resulting in an algal bloom. This can have two severe consequences: dead zones and harmful algal blooms.

A dead zone is an area where there is very little oxygen in the water column, seriously limiting the number and types of organisms that are able to survive. The rapid algal growth caused by eutrophication can lead to competition for sustenance between those organisms, and consequently results in the death of massive amounts of algae. As organisms decay after death, they use oxygen. This process depletes the oxygen from the water, resulting in hypoxic or anoxic conditions, where either most or all of the oxygen is depleted from the water. This creates a dead zone, where many organisms die as a result of the lack of oxygen, and many of those that survive have health defects. Grave examples include the seasonal dead zone in the Gulf of Mexico and the enormous permanent dead zone in the Baltic Sea. The number of such dead zones seems to double in number every 10 years.

Harmful algal blooms (HABs), known commonly as "red tides," are algal blooms where there are excessive amounts of certain types of phytoplankton. Certain types of phytoplankton produce toxins that are dangerous to other marine organisms and humans. HABs can have numerous impacts on marine organisms depending on various factors, but can result in problems with developmental, immunological, neurological, and reproductive systems. When humans ingest seafood that has come into contact with a HAB, the result can be illness or even death. When a HAB occurs, fishing is usually temporarily banned in the area, and people should stay out of the water if there is an obvious bloom.


A harmful algal bloom, commonly called "red tide" for the reddish appearance of the algae.
Source: Woods Hole Oceanographic Institution, www.whoi.edu.

The presence of nutrients can go largely undetected until it is too late. Nutrients are not visible and water probes must be analyzed to obtain data. Only with knowledge of the condition of an aquatic system can action be taken. Creating sustainable coastal environments requires skill in identifying pollution problems, understanding technical options, and integrating information to propose effective policy solutions. In the marine affairs program, you can learn more about oil spills, harmful algal blooms, and other marine pollutants by taking various classes. These are persistent marine problems that are highly relevant in the marine affairs field.