Alafia River Minimum Flows and Levels - Southwest Florida Water ...

Bryant (1990) have demonstrated that different macroinvertebrate life stages also
require different hydraulic conditions to achieve completion of life cycles, just as
fish species have very different spawning, incubation, and maintenance
requirements. Recently, Gore et al. (2001) demonstrated that inclusion of
macroinvertebrate criteria often dramatically altered decisions on flow allocations
versus those based upon analysis of fish species alone. By the same token, we
recommend that the District evaluate whether additional habitat suitability curves
should be developed and PHABSIM analyses be conducted for other species
that may be more sensitive to hydrological change than the three common
centrarchid fishes identified in the Middle Peace report. These other species
might include key invertebrates in the rivers of the District.
Changes in velocity distribution and substrate/cover characteristics at regular
intervals, combined with stage/discharge relationships, provide the calibration data
for PHABSIM. Habitat suitability curves were developed for spotted sunfish
(Lepomis punctatus), largemouth bass (Micropterus salmoides), bluegill (Lepomis
macrochirus), and macroinvertebrate community diversity (Gore et al. 2001, Stuber
et al. 1982). These are appropriate species for consideration in rivers of the
southern Florida peninsula and their selection is validated by data presented on fish
abundance in the appendices to the MFL reports. Helpful information on the
methods used for aquatic invertebrate and fish community assessment was
included in Chapter 4 of the Alafia report, but was absent from the Myakka report. It
is not clear whether such assessments were only conducted for the Alafia or
whether the same assessments were carried out for the Myakka but the information
was left out of the Myakka report. The need for continued development and
refinement of habitat suitability curves for these species and other species of
concern remains a necessary long-term goal (as noted below), but the peer review
panel affirms that the best available information was used in the PHABSIM
modeling for the Alafia and Myakka rivers. This strengthens the specific
recommendations for MFLs made in the report.
Over the long term, we recommend that the District focus research on evaluating
and potentially developing habitat suitability information on additional species or
groups of species that may be more sensitive to changes in hydrological regimes.
Of particular concern would be any listed, imperiled, or endemic species, species
tracked by the Florida Natural Areas Inventory (FNAI) (e.g., ironcolor shiner,
present in both the Alafia and upper Myakka rivers), wading birds and fish
species with preferences for stream edges or banks that might be the first places
to feel the effects of reduced flows. Similarly, it may be useful to develop better
habitat suitability information for certain exotic species present in these rivers
(e.g., blue tilapia (Oreochromis aureus)) to ensure that reduced flows do not
improve habitat conditions for such species or facilitate their invasion of new
habitat. Additional species of concern in the Alafia and Myakka rivers that may
not be directly amenable to the PHABSIM approach include several species of
rare plants inhabiting the floodplain (FNAI Element Occurrence Database, 2005).
Appendix A XI