Harmful Algal Blooms (HABs)
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Algae is a microscopic plant-like organism that is present in sea water in low amounts. These organisms are photosynthetic and are critical to life on Earth. They are the key primary producer in most marine food webs. By undergoing photosynthesis they produce oxygen--in fact, these single-celled organisms produce about 1/2 of the world's oxygen.
Not all algae are harmful--if the algae produces a toxic or harmful effect on people, marine animals, or birds it is considered "harmful". A Harmful Algal Bloom is when there is a population explosion. The huge amount of plankton can cause the water to change colors, which is why these events are often called "red tides". The color change may not actually be red, but rather yellow, orange, green or brown. |
These plankton can harm other organisms if ingested. Another issue with algal blooms is oxygen depletion. If a large amount of the algae dies, the decomposition process can consume enough oxygen to cause a "net depletion". (www.vims.edu/bridge).
The causes are not fully understood. Factors such as water temperature, the addition of extra nitrates and phosphates (from water pollution), and even water flow are thought to play a part in HABs.
The causes are not fully understood. Factors such as water temperature, the addition of extra nitrates and phosphates (from water pollution), and even water flow are thought to play a part in HABs.