Infaunal benthic communities include bivalves (clams), worms
(polychaetes and oligochaetes), amphipod crustaceans, insect larvae, etc., that live
within the marine substrate, in other words, these are the tiny critters that live in the mud on the sea floor. They are heavily preyed upon by crabs and fish.
Community composition and structure differ with habitat, salinity, and dissolved oxygen.
Community composition is sensitive to changes in water quality, particularly
contaminants (e.g., pesticides, heavy metals), changing salinity, and dissolved oxygen
(related to nutrient and organics enrichment). Infaunal benthic communities are
indicators of overall estuarine health in FL Bay and Biscayne Bay, and can be valuable
indicators in ecotonal areas or areas of suspected contaminant input. They respond to
the general water quality and contaminant levels at a site through time. A South Florida
index for biological integrity has yet to be developed.