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According to the EPA, lakes can be classified by biological productivity, or the amount of living materials (primarily algae) supported within them. Oligotrophic is the term we use for the least productive lakes, mesotrophic for moderately productive, and eutrophic for the most productive. Before the Great Lakes area was populated, the waters were oligotrophic, remaining clear and cool. Now, however, these lakes are showing increased turbidity (murkiness) and greater populations of algae are evident. These are signs of eutrophication.
According to the EPA, lakes can be classified by biological productivity, or the amount of living materials (primarily algae) supported within them. Oligotrophic is the term we use for the least productive lakes, mesotrophic for moderately productive, and eutrophic for the most productive. Before the Great Lakes area was populated, the waters were oligotrophic, remaining clear and cool. Now, however, these lakes are showing increased turbidity (murkiness) and greater populations of algae are evident. These are signs of eutrophication.
While an increase in algae may not seem to be a serious threat, it does indeed pose serious hidden dangers to a lake. When these large numbers of algae die, they sink to the bottom and decompose. The organisms that break down the plants deplete the dissolved oxygen near the bottom. When this occurs, entire species of bottom-dwelling organisms can be killed due to lack of oxygen, thus disrupting the food chain.
While an increase in algae may not seem to be a serious threat, it does indeed pose serious hidden dangers to a lake. When these large numbers of algae die, they sink to the bottom and decompose. The organisms that break down the plants deplete the dissolved oxygen near the bottom. When this occurs, entire species of bottom-dwelling organisms can be killed due to lack of oxygen, thus disrupting the food chain.
Several variables control the productivity of a lake: temperature, light, depth and volume, and amount of nutrients received from the environment. When scientists looked at the eutrophication occurring in the Great Lakes, they determined excess nutrients to be the cause. Two major factors were found to be phosphate detergents (high in phosphorus) and inorganic fertilizers (containing nitrogen, phosphorus, and potassium). Although there has been some progress in regulating the use of these two culprits, excess nutrients are still seeping into our lakes.
Several variables control the productivity of a lake: temperature, light, depth and volume, and amount of nutrients received from the environment. When scientists looked at the eutrophication occurring in the Great Lakes, they determined excess nutrients to be the cause. Two major factors were found to be phosphate detergents (high in phosphorus) and inorganic fertilizers (containing nitrogen, phosphorus, and potassium). Although there has been some progress in regulating the use of these two culprits, excess nutrients are still seeping into our lakes.
oligotrophic
oligotrophic
oligo = few or little
troph = nourishment
ic = adjective form
oligotrophic = little nourishment (having little phytoplankton or algae)
mesotrophic
mesotrophic
meso = middle
troph = nourishment
ic = adjective form
mesotrophic = average nourishment (having average phytoplankton or algae)
eutrophic
eutrophic
eu = good
troph = nourishment
ic = adjective form
eutrophic = good nourishment (having lots of phytoplankton or algae)
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