Signs of Eutrophication in an Area

More Algae

• One of the major signs of eutrophication is an increase of algae growing on the surface of the lake. This is caused by phytoplankton receiving excessive nutrients. The phytoplankton in the water is the first link in the food chain. They begin reproducing more rapidly, which causes algae blooms. Algae blooms are a common occurrence on many lakes. However, excessive algae blooms can cause a series of problems such as red tides.

Red Tides

• According to the Chemgapedia website, eutrophication can affect oceans in shallow and sheltered coastal areas. These coastal regions often suffer from a condition called red tide. Red tides are large-scale blooms of algae, which may be brown, red or pink in color. These algae blooms move with the tides; therefore, they appear and disappear throughout the day. Thicker algae levels during red tide movements indicate an increase in eutrophication.

Decreased Light

• Eutrophication can also cause a decrease in available sunlight. The chemicals that cause eutrophication often float on the surface of the lake, blocking out sunlight. Blocked sunlight leads to an increase in algae blooms, murky water that is hard to navigate and the death of marine plant life. Plants need sunlight to photosynthesize. Dying plants can lead to a serious disruption in the food cycle which, when serious enough, according to the U.N. Environmental Programme website, can lead to a complete collapse of the ecosystem.

Fish Deaths

• Algae need oxygen to survive. Normal levels of algae don't cause a problem in the oxygen supply in a body of water. However, above-normal levels of algae will use above-normal levels of the lake's oxygen. Fish may begin suffocating due to a lack of oxygen. Eutrophication can also cause the death of plant life in the lake. Some breeds of algae actually produce toxins that can kill fish. These toxins aren't harmful when algae levels are normal. Contaminated fish can pass these toxins onto any animal that consumes them.