The Environmental Dangers of Giant Algae Slicks

We’ve all heard of man-made slicks covering our ocean surfaces such as oil slicks, but what about the slicks that mother nature creates without our help? Giant algae slicks are a major environmental problem. These algae slicks or “algae blooms” can occur in fresh or oceanic waters, can cover a massive area of water, and cause many problems for the organisms that live in that area. In fact, most of the places where these algae slicks occur are considered “dead zones”. The algae use up so much of the oxygen and other resources in the area that a portion of the body of water is no longer able to support any other life.

Algae is quite common and is an important part of the marine ecosystem. These single-celled, plant-like organisms can be found on the surface of water that is well lit. They are an important part of the food chain that many species depend upon for survival. Only about two percent of algae form harmful slicks worldwide. In addition to exhausting the area’s resources, they have also been known to cause contamination throughout the food chain, even as far up as the humans who eat contaminated sea food. Some harmful forms of algae also produce neurotoxins that cause massive mortality rates in marine life.

These harmful slicks can occur anywhere in the world. Sometimes, these algae blooms appear to be a product of natural circumstances, but other times, they are clearly influenced by human activity and pollution. A recent example occurred on China’s eastern coast, near the city of Jiaonan in the Shandong province, which was threatened by a massive algae bloom covering 200 sq km (80 sq miles). Algae blooms could have a major effect on marine life and the tourism industry in the area. China frequently has possible coastal algae bloom issues due to the pollution.

Chemicals released into the waters are a major cause of these dangerous algae slicks, nitrogen and phosphorous being two of the main chemicals. The increase in nitrogen and phosphorous in the water is known as eutrophication and a large part of the algae’s composition involves these two chemicals. If they are not abundant in the water, the growth of the algae would be limited and would not result in a “bloom”. Under normal circumstances, the amount of oxygen needed by the algae during non-light hours would not drastically affect the oxygen in the water, but when an algae bloom occurs, a large amount of oxygen is needed both at night (when sunlight isn’t available for photosynthesis) and during the bacterial decomposition of dead cells. Algae drains the oxygen from the water, depriving all other organisms of the ability to survive in the area.

There are many algae blooms like the one near China’s coastline throughout the world that are threatening the natural marine ecosystems. One of the most well-known is the giant algae slick in the Gulf of Mexico. This dead zone is over 22,126 sq km large (8,543 sq miles). The pollution comes from the run-off of the Mississippi River that carries massive amounts of run-off from the Midwestern region of the United States, the heart of the US agricultural business. These farms use fertilizers to boost their crop yield and it is the chemicals in these fertilizers (phosphorous and nitrogen) that eventually make it into the Gulf.
Washed up algae bloomPhoto: Emily Nauman

What can we do to help stop these harmful forms of algae forming in our waters? Supporting organic agriculture, for example. Organic agriculture does not use the super nutrient style fertilizers that end up creating pollution in the water. Or getting involved with organizations such as Florida Red Tide Solutions ( and encouraging our local representatives to pass legislation to promote more environmentally friendly farming and manufacturing processes to keep our land and oceans clean and safe for all.