Macroinvertebrates

Many different animals live in lakes and streams and macroinvertebrates make up a large portion of the population.  Macroinvertebrates are animals without backbones that are large enough to see with the naked eye.  These include organisms such as snails, mussels, worms, insects, and crayfish.  Macroinvertebrates are sensitive to environmental conditions affecting habitat such as water chemistry, water flow, temperature, suspended solids, and dissolved oxygen.  The effects of different water quality conditions on aquatic insect numbers and kinds present are particularly well known.  Aquatic insects are widely used in biomonitoring programs for assessing water quality.  Different metrics or ratings describing insect community structure are calculated for the evaluation of inflow and tailwater quality associated with each of the 20 lake projects as well as the Ohio River.

Macroinvertebrate sampling. Photos by Louisville District Water Quality Team.

Phytoplankton

Phytoplankton are free-floating microscopic organisms in aquatic ecosystems and are photosynthetic (convert light energy into chemical energy, like plants). This includes several species of algae and cyanobacteria (blue-green algae). Because phytoplankton compose much of the bottom of the food chain, lake and river ecosystems depend heavily on phytoplankton. Also, phytoplankton are very sensitive to water quality conditions and make excellent indicators of water quality. Because of these reasons, we monitor and assess phytoplankton communities to improve our understanding of a lake’s water quality. Phytoplankton can effectively indicate certain types of pollution (notably nutrient overloading) and can be used to track trends in pollution. We also conduct special phytoplankton analyses when monitoring a harmful algal bloom (HAB) to evaluate cell counts, types of species, and other community metrics.

Various species of cyanobacteria. Photos by Louisville District Water Quality Team.