Studies of algal and macroinvertebrate communities have been among DEP's most cost-effective and successful assessment tools of overall system health. Advantages of using algae and benthic invertebrates include their ease of sampling, their strategic positions in the food web, and their ability to respond quickly (within days or weeks) of a human physical or water quality disturbance.

Measures of Macroinvertebrate Community Health

Several different measurements of macroinvertebrate community health are routinely employed to determine the status of a system. These are:

• Taxa richness: the number of different types of organisms present in a system.
• Shannon-Weaver diversity: an index which is specified in the Florida Administrative Code as a measure of biological integrity.
• Percent contribution of the dominant taxon: related to diversity, used for analysis of qualitative samples.
• Numbers of pollution sensitive taxa: several different invertebrate indices based on this principle, including the Florida Index and the Lake Condition Index.
• Ephemeroptera/Plecoptera/Trichoptera Index: am index which sums the number of these kinds of organisms present. A related parameter, the Ephemeroptera/Plecoptera/Odonata Index, is also sometimes used.
• Community structure: measurements of shifts in proportions of major groups of organisms, compared to reference conditions.
• Trophic composition/feeding guilds: determination of shifts in the feeding strategies of invertebrates.
• The Stream Condition Index for Florida (SCI): a composite macroinvertebrate index made up of several of the measurements listed above.
• Habitat Assessment: quality of the local environment with respect to the needs of the organisms investigated.

The Standard Operating Procedures used in performing benthic macroinvertebrate analyses can be viewed or downloaded from the Biology Section SOPs.