Chapter 1 Minimum Flows and Levels - Southwest Florida Water ...

can respond with sufficient detail to allow development of appropriate
mathematical models of habitat use.
Type II curves are based upon frequency distributions for use of certain variables
(e.g., flow), which are measured at locations utilized by the target species.
Curves for numerous species have been published by the U.S. Fish and Wildlife
Service or the U.S. Geological Survey and are commonly referred to as “blue
book” criteria.
Type III curves are derived from direct observation of the utilization and/or
preference of target organisms for a range of environmental variables (Manly et
al. 1993). These curves are weighted by actual distribution of available
environmental conditions in the stream (Bovee et al. 1998). Type III curves
assume that the optimal conditions will be “preferred” over all others if individuals
are presented equal proportions of less favorable conditions (Johnson 1980).
Based on dominance of the spotted sunfish (Lepomis punctatus) in rivers within
the District, a habitat suitability curve was created for this species. Since most of
the regional experts in fish ecology were unfamiliar with development of habitat
suitability criteria, a hybrid of the roundtable and Delphi techniques was used to
develop a Type I curve. For this effort, a proposed working model of habitat
suitability criteria was provided to 14 experts for initial evaluation. The proposed
suitability curves were based on flow criteria for redbreast sunfish (Lepomis
auritus) (Aho and Terrell 1986) modified according to published literature on the
biology of spotted sunfish. Respondents were given approximately 30 days to
review the proposed habitat suitability criteria and to suggest modifications. Six
of the 14 experts provided comments. In accordance with Delphi techniques, the
suggested modifications were incorporated into the proposed curves. Suggested
modifications that fell outside of the median and 25% interquartile range of
responses were not considered unless suitable justification could be provided.
Modified Type II habitat suitability criteria for the largemouth bass (Micropterus
salmoides) and bluegill (Lepomis macrochirus), two other common fish species in
the Braden River, were established using USFWS/USGS “blue book” criteria
(Stuber et al. 1982). Curves for these species have been widely used in
PHABSIM applications.
Type III habitat suitability criteria for macroinvertebrate community diversity were
established based on suitability curves published by Gore et al. (2001). Modified
substrate and cover codes used for criteria development were established
through consultation with District and Florida Fish and Wildlife Conservation
Commission staff. For this effort, emphasis was placed on invertebrate
preference for macrophytes, inundated woody snags and exposed root habitats.
Per recommendation of the peer review panel for the middle Peace River, the
District intends to evaluate and develop additional habitat suitability curves for
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