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algal bloom
 |
An algal bloom leaves a green scum-like substance
on the waters of the Indian River Lagoon, Florida, in the mid-1990s
|
A sudden spurt of algal growth that may be due to an abnormal amount of
sunlight over a lengthy period or greatly increased amounts of phosphorus
or nitrogen entering the aquatic ecosystem from sewage systems and agricultural
fertilizers. Excessive growth of the algae
causes destruction of many of the higher links of the food web. Algae that
die and sink to the bottom at the end of the growing season stimulate massive
growth of bacteria the following year, resulting in depletion of oxygen
in the deeper water layers. This may result in fish kills and replacement
with less valuable species who may be more tolerant of increased phosphorus
levels. Deoxygenation also may cause chemical changes in the mud on the
bottom, producing increased quantities of chemicals and toxic gases. All
these changes further accelerate the eutrophication (aging) of the aquatic
ecosystem.
Related category
• ECOLOGY
AND THE ENVIRONMENT
Source: NASA
Goddard Space Flight Center
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