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Water What-ifs

Reasons to Assess Macroinvertebrate Populations

Reasons to Assess Macroinvertebrate Populations
  • Aquatic macroinvertebrates are an important part of the food chain found in and around a body of water. 

Aquatic macroinvertebrates are a link in the aquatic food chain. In most streams, the energy stored by plants is available to animal life either in the form of leaves that fall in the water or in the form of algae that grows on the stream bottom. The algae and leaves are eaten by macroinvertebrates. The macroinvertebrates are a source of energy for larger animals such as fish, which in turn, are a source of energy for other animals and even man. 

  • Aquatic macroinvertebrates differ in their sensitivity to water pollution.

Some aquatic macroinvertebrates cannot survive in polluted water. Others can survive or even thrive in polluted water. In a healthy stream, the macroinvertebrate community will include a variety of pollution-sensitive macroinvertebrates. In an unhealthy stream, there may be only a few types of non-sensitve macroinvertebrates present.

  • Aquatic macroinvertebrates provide information about the quality of a stream over long periods of time.

It may be difficult to identify stream pollution with water analysis such as pH and dissolved oxygen which can only provide information at the time of sampling. Even the presence of fish may not provide information about a pollution problem because fish can move away to avoid polluted water and then return when conditions improve. However, most aquatic macroinvertebrates cannot move to avoid pollution. A macroinvertebrate sample may provide information about pollution that is not present at the time of sample collection.

  • Aquatic macroinvertebrates are relatively easy to collect.

Useful aquatic macroinvertebrate data is easy to collect without expensive equipment. The data obtained by taking a macroinvertebrate survey can serve to indicate the need for additional data collection on water samples.

Water What-ifs Home | Macroinvertebrate Lessons

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©1998 April J. Cleveland for Science Junction, NC State University.
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