Habitat

Habitat Suitability Criteria Development and Improvement for Instream Habitat Assessments Conducted in Support of Environmental Flows in Florida

Florida’s regulatory framework requires the establishment of minimum flows and minimum levels to protect aquatic ecosystems from significant harm. One of the primary methods used by water resource managers to evaluate significant harm is by assessing instream habitat, which relies on Habitat Suitability Criteria (HSC) curves to evaluate the relationship between flow regimes and habitat availability for aquatic species. This study aimed to improve the scientific foundation and applicability of HSC curves used in Florida by compiling, reviewing, updating, and developing new curves tailored to the state’s unique hydrography. The primary product of Phase 1 was the development of the Florida Handbook of Habitat Suitability Criteria, which thoroughly reviewed HSC curves being used in Florida and provided guidance for their application in major the major Florida drainages to promote consistency among instream flow practitioners. Phase 2 updated the historical habitat classification system to a new habitat classification system of discrete and unambiguous habitat descriptions developed by the Florida Fish and Wildlife Conservation Commission (FWC). Updates were made by analyzing the FWC’s river monitoring database for freshwater fish communities, which contains primary cover and substate types associated with individual 100-m electrofishing transects used to sample fish communities throughout Florida. Updates to aquatic invertebrate species and groups were similarly made by evaluating FWC’s statewide aquatic invertebrate database and using literature review and best professional judgment to assist with the development of invertebrate habitat use functions.

The project involved a comprehensive review of existing HSC curves, modifications based on empirical data from Florida’s river monitoring programs, and the development of new curves through field studies and expert consensus using the Delphi technique. The resulting HSC library increases the transparency, defensibility, and ecological relevance of instream flow assessments in Florida. The HSC library and supporting guidance document provide water managers with a tool to support sustainable water resource planning and rulemaking across diverse freshwater systems in the state.