Ecologic and precursor success criteria for south Florida ecosystem restoration

A Science Sub-Group Report to the Working Group of the South Florida Ecosystem Restoration Task Force

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CHAPTER 14:

SOUTH FLORIDA SUCCESS CRITERIA ESTUARINE AND INLAND FISH POPULATIONS AND COMMUNITIES

Ken Cummins
Ecosystem Restoration Department, South Florida Water Management District

TECHNICAL APPROACH

The primary technical approach involved a workshop sponsored by the Florida Center for Environmental Studies (CES), entitled " A Mini-Conference on fish. Coastal and Inland Fish Communities in South Florida: Past, Present, and Future Assessment of ConditionÓ. The Mini-Conference was held at CES on the North Campus of Florida Atlantic University. Although the majority of the material presented in this document was generated and/or discussed at the Mini-Conference, the participants, listed below, are not responsible for any errors or omissions in the document. Those are solely the responsibility of the author*.

Albrey Arrington - Kissimmee River Restoration Division, Ecosystem Restoration Department, South Florida Water Management District (SFWMD) (407-687- 6499)

Steve Bartone - Institute for Coastal and Estuarine Research, University of West Florida (904-474-3251)

*Ken Cummins - Ecosystem Restoration Department (ERD)t, South Florida Water Management District (407-624-6901) Don Fox - Okeechobee Office, Florida Game and Freshwater Fish Commission (941- 763-4666)

Nancy Gassman Department of Natural Resources Protection, Broward County (305- 519-1464)

Frank Jordan, Biology Department, Jacksonville University (904-744-3950 [ext. 7369])

Bill Loftus - National Biological Service, Everglades (305-242-7835)

Mike Schirripa - National Marine Fisheries Service, National Oceanic and Atmospheric Administration (305-361 -4221)

Joel Trexler - Department of Biology, Florida International University (305-348-1966)

Peggy Wilzbach - Department of Environmental Resources Management, Palm Beach County (407-233-2443 [Present position: CES, 561 -691 -8575.]

CES/SFWMD Staff

Todd Messenger - CES
Kim O'Dell CES
Barbara Welch ERD, SFWMD

The participants in the workshop also jointly prepared a list of other fish workers who had a significant interest in, and could potentially make, contributions to a data bank on coastal and inland fishes of South Florida (see Appendix 1 and networking discussion below).

RATIONALE

In a great many environmental issues, the basis for judging ecosystem health depends on the status of populations of specific harvestable fish species or communities of fish, for example the relative dominance of non-native fish species in the assemblage. In addition to these economic and ''charismatic" features of coastal and inland fishes of South Florida, fish serve as excellent integrators of environmental conditions of lower trophic levels and juveniles and small species are important food of wading birds and large reptiles. For all these reasons, it is difficult to imagine any meaningful environmental assessment of coastal and inland waters of south Florida that could be made without consideration of fishes.

RECOMMENDED CRITERIA

Unfortunately, except for some specific regions and/or habitats (e. g. Eliocharis beds in the Everglades), specific time spans for certain species in particular locations (e. g. about 20+ years data on spotted seatrout, Cynoscion nebulosa, in Florida Bay or 30 + years for large mouth bass, Micropterus salmoides, in Lake Okeechobee), it is not presently possible to provide extensive "report card" reviews for fish in the coastal and inland fisheries of the south Florida ecosystem (Kissimmee Lakes to Florida Bay plus east and west coast estuaries). Abundance data for populations of individual fish species or for fish communities are perhaps the most variable and difficult to interpret. Therefore, it is proposed that other attributes of fish populations and communities (i. e. assemblages of populations in a particular habitat) might at present constitute more reliable criteria for assessing the condition of fish in South Florida and to track changes as further land use alterations and restoration efforts proceed in the region.

The seatrout, Cynoscion nebulosa, is an excellent candidate for use in assessing the condition of coastal fish in South Florida because it is a species entirely confined to estuaries throughout its life cycle and along with the gray snapper (Lutjanus griseus ) constitute the most popular coastal sport fishes (as judged by angler hours) in South Florida. The common snook, Centopomus undecimalis is also limited to estuaries throughout its life cycle (although it now migrates to, and sumives for long periods in Lake Okeechobee. This has come about because connections to the lake by east and west coast estuaries has been engineered. Other coastal species for which some data exist are the gray snapper and the red drum (red fish, Sciaenops ocellatus ), but these are estuarine dependent species which recruit from offshore waters, making assessment of population characteristics all the more difficult.

The largemouth bass (Micropterus salmoides ) is one of the most popular game fishes of North America .The premiere largemouth fishing in the world is in Lake Okeechobee and very large individuals are caught in smaller bodies of water (including the canal system) throughout South Florida. This makes the largemouth almost a required subject of analysis in the evaluation of inland Florida fish populations. The black crappie (Pomoxis nigromauculatus ) and numerous other centrarchids are also heavily sought after as game fish, but the databases for these species are not as extensive. Because centrarchids are not common in the Everglades, other wetland candidate target species need to be designated. Candidates are bluefin killifish (Lucania goodei ) and the flag fish ( Jordanella f loridae ). The Florida gar (Lepisosteus platyrihincus ) would be useful as an indicator large predator.

Success Criteria

Taxa richness based on individuals in a large qualitative sample, again collections taken from the full suite of habitats available in the system.

Ratio of Exotic to Native Species would be used to evaluate the significance of introductions. This is a presence/absence ratio independent of abundance.

Condition of individuals in a population relative to regional and/or historical data for a given species. The analysis can be based on non-quantitative samples, providing all sub-habitats in the system are sampled (e. g. main river channel, backwaters and sloughs, side channels, floodplain in the Kissimmee River system) and all size classes are well represented in the samples. The analysis is independent of sample size over broad range if over 50 individuals are collected and the full size range of the population is well represented. A regression of individual lengths against biomass (or a correlation ellipse) for the sample population is statistically compared to that for a reference population - regional and/or historical. That is, are the slopes different in a positive or negative direction? Or, with a small sample size, are the individuals members of the statistical population of the reference regression? The statistical analysis is then used to determine if the population in question has declined or improved (e. g. p < 0.05 for slopes and + or - direction, or stayed the same, p > 0.05 for slopes).

Relative abundance of individuals of different native species of a community in a given system. For example, as the middle Kissimmee River is restored by de- channelization and re-establishing more normal hydrologic regimes, sandy-bottom habitats that are now rare in the remnant channels but were dominant in the pre- channelized river-floodplain system will be re-established. The black banded darter (Percina nigrofasciata ) that inhabits sandy bottoms would be predicted to significantly increase in relative abundance as restoration proceeds. This is an example of a native non-game species with a predicted high utility for success criteria in a known changing environment the gradually restored Kissimmee River-floodplain ecosystem.

Historic Condition

Condition of individuals in a population relative to regional and/or historical data for a given species. For example, the length and weight of a large mouth bass specimen collected from the restoration section of the Kissimmee River would be compared to a complete length-weight data set for the Kissimmee Lakes, Kissimmee River, Lake Okeechobee region or a separately collected data set from a site not influenced by the restoration (e. g. isolated wetland ponds on the Audubon Kissimmee Prairie Preserve). The analysis can be based on non-quantitative samples, providing all sub-habitats in the system are sampled (e. g. main river channel, backwaters and sloughs, side channels, floodplain in the Kissimmee River system) and all size classes are well represented in the samples. The analysis is independent of sample size over broad range if over 50 individuals are collected and the full size range of the population is well represented. A regression of individual lengths against biomass (or a correlation ellipse) for the sample population is statistically compared to that for a reference population - regional and/or historical. That is, are the slopes different in a positive or negative direction? Or, with a small sample size, are the individuals members of the statistical population of the reference regression? The statistical analysis is then used to determine if the population in question has declined or improved (e. g. p < 0.05 for slopes and + or - direction, or stayed the same, p > 0.05 for slopes). An additional population condition factor can be derived by comparing, over time, the mean annual size of a reproductive age individual in the population to the mean minimum size for reproduction for the species. As the mean size shows a trend toward the minimum reproductive size, the population can be evaluated as at risk.

Actual historic condition, here defined as prior to non-indigenous settlement, is always difficult to document around South Florida is no exception. The historic condition may be so removed from the present status (i. e. baseline conditions prior to initiation of restoration efforts) of some South Florida ecosystems, that only partial recovery is a feasible goal for restoration. An example is the Kissimmee River which had changed as much between 1850 and 1900 as between 1900 and the 1960s when it was channelized (Sedell, Hindle, Burnett, and Cummins, 1996. Historical changes in the geomorphology and riparian corridor of the Kissimmee River since 1850. South Florida Water Management District, Draft Manuscript in review) due largely to channel snagging and the removal of woody vegetation from the River Valley to support the wood-burning, paddle wheel steamer traffic. This major loss of large woody debris must have represented a significant loss of fish habitat (e. g. Maser and Sedell 1994) which may never be recoverable. Because data are absent or largely anecdotal, an operational historic condition needs to be used as the conceptual reference condition for some South Florida ecosystems such as the Kissimmee River In the case of fish populations and communities, this means conditions in the last 2 to 3 decades would form the basis of the conceptual reference.

Space for time substitution may be required when, as is most often the case, adequate historic information is not available. The strategy would be to use spatially extensive data as an alternative to a long term record at a given site. That is, use a large number of sites in an ecoregion evaluated over time (e. g. presence/absence, "creel census", etc. for common species ).

Baseline Condition

Baseline condition is defined here as present condition. To insure a productive future for the evaluation of trends in the condition South Florida ecosystems using the analysis of fish populations and communities, a standardized format for on-going and needed ("gap") data is essential.

Restoration Expectations

As detailed in the recent issue of the Journal Restoration Ecology devoted to the Kissimmee River restoration (e. g. Dahm et al. 1996), the pivotal question is "restore to what"? The evaluation that is recommended for coastal and inland fish populations and communities of South Florida is trend analysis from the actual historical condition (pre- settlement or aboriginal) through the operational historical condition (20 + years) and the present a "restored" condition. The restored condition would be viewed as some combination of the actual and operational historical condition as shaped by the extent of existing data and the realities of land use changes in South Florida (e. g. Trexler 1996).

Scoring

As evidenced in the description above, several types of scoring are recommended.

Taxa Richness: Scoring would be based on analysis of long term (10+ years) data sets on presence/absence of taxa in a given habitat would be indexed to the trend in long term variation in the record. The record up to the year to be evaluated would be considered the baseline trend. Changes equal to or greater than the range of maximum/minimum values for the baseline trend period would be considered sign)ficant. That is, if the max./min. range in richness over the baseline period was 10 taxa, a change of 20 taxa for the "report card" year would be considered significant. These calculations should be based on native species only, as a separate criterion for exotics is proposed.

Ratio of Exotic to Native Species: The ratio would be used to evaluate the significance of introductions. This is a presence/absence ratio independent of abundance. The same evaluation of significance as for taxa richness above would be used. However, a change of equal to or greater than the max./min. would be used to provide greater sensitivity to probable deleterious introductions.

Condition of individuals in a population relative to regional and/or historical data for a given species. The analysis can be based on non-quantitative samples, providing all sub-habitats in the system are sampled (e. g. main river channel, backwaters and sloughs, side channels, floodplain in the Kissimmee River system) and all size classes are well represented in the samples. The analysis is independent of sample size over broad range if over 50 individuals are collected and the full size range of the population is well represented. A regression of individual lengths against biomass (or a correlation ellipse) for the sample population is statistically compared to that for a reference population - regional and/or historical. That is, are the slopes different in a positive or negative direction? Or, with a small sample size, are the individuals members of the statistical population of the reference regression? The statistical analysis is then used to determine if the population in question has declined or improved (e. g. p < 0.05 for slopes and + or - direction, or stayed the same, p > 0.05 for slopes).

Relative abundance of individuals of different native species of a community in a given system. As for taxa richness, scoring would be based on analysis of long term (10+ years) data sets in a given habitat and indexed to variations (max./min.) in trends of abundance. A significant change would also be taken as >= the max./mint range in the baseline record. In addition, recurrence intervals for the data would be calculated to better index the information to variations in hydrology. This analysis assumes that hydroperiod is a major direct (seasonal water depth) or indirect (e. g. salinity, nutrient concentrations) controlling factor of fish abundance. Annual abundance data of a given species (or community) are ranked in descending order. and that ranking Taking the total years of record plus one as a fraction of the ranking of a given year yields the recurrence interval in years. These results can be expressed as a probability in the form of a one in x (i. e. calculated number)of years chance of having an abundance as high (or low) as the abundance of the year of observation. For example, using a 20 year record and observed abundance ranking of 8 would indicate that fish abundance would be of that order of magnitude every 2 to 3 years based on usual variation over 20 years, or have a probability of occurrence in any one year of about 38%. Any probabilities > or < 50% would be evaluated as potentials for significantchange (e. g. 10%). The data base for relative abundance could be relative ranking plots for dominat species, that is species in rank order plotted against number of individuals.

The most severe problem with abundance data is to insure that the catch per unit effort information is compatible from year to year and place to place. Unless the data are truly quantitative, such as block net or throw trap samples, they may be of very limited use.

SUPPORTING INFORMATION NEEDS

There is a clear need to establish standardized data bases to integrate available information on fish populations and communities in South Florida. The critical first task would be to produce a complete inventory of data bases on coastal and inland fishes in the South Florida Ecosystem. An important non-trivial component of this large task is to convert data bases to some inter-convertible format. This is especially critical for abundance data based on catch records such as commercial harvest or sport fishing "creel census" which are strongly influenced by changes in catch regulations. It is also noteworthy that very few studies have compared the efficiency of the various fish population sampling devices and counting techniques.

DEVELOPMENT OF OTHER SUCCESS CRITERIA

As indicated above, the most obvious need is for standard techniques of assessing abundance. If harvest data (e. g. creel census, commercial sport fishing logs) are to be legitimately used, significant effort at standardization is necessary.

Other criteria for assessing the condition of fish populations in coastal and inland waters need additional resources to allow development. Among these perhaps the most critical is recruitment. Quantitative estimates of young of the year abundance (strength of year class) are rare for most species of fish in South Florida. Because recruitment success is and excellent predictor of the condition of coastal and inland fish populations, resources need to be committed to collect abundance data. Other categories that need additional support are measures of gonadosomatic index for selected species and measures of parasite/disease levels ( or incidence of tumors as detailed in another criteria assessment document) in selected populations.

SCIENTIFIC SUPPORT REQUIRED

Improving and Testing Recommended Success Criteria

As detailed above, significantresources are urgently needed to develop integrated databases for the fish success criteria outlined above. As indicated, this is a two step process: 1) locating the data bases and establishing "ownership" and, 2) developing a standardized data base and establishing rules of accessibility. This effort would require the participation of all the "owners" (responsible parties) of the databases to be integrated. The new database also must be reflective of a consensus format for data collection in the future.

Interpretation of Results

The workshop on Fish co-sponsored by CES and SFWMD showed that the workshop format would be workable in interpreting data on coastal and inland fish populations and communities in South Florida. Such workshops would be likely to be successful only if the issue of compatible/comparable data bases had been resolved. For example, such concensus building workshops for the Florida Keys ecosystem monitoring form the basis for project integration in the area sponsored by NOAA's National Ocean Service and Florida DEP's Florida Marine Research Institute.

Development of Potential Success Criteria

Again, the workshop format could be used to examine existing and developing new criteria for fish population and community success in South Florida, such as new concepts in combined indicies and the analysis of fish communities by feeding or habitat guilds.

DISCUSSION

It is clear form the results of the Fish Criteria Workshop that separate criteria must be established for inland and estuarine fish species, populations or communities. For estuarine systems, species without a dominant estuarine component in their life cycle would be excluded.

Some examples of existing data sets on estuarine and inland fish populations and communities are summarized in Table 1 below. (FMRI = Florida Marine Research Institute; DEP = Florida Dept. Environmental Protection; CPUE = catch per unit effort; NMFS = National Marine Fisheries Service; FGFWFC = Florida Game and Freshwater Fish Commission; ENP = Everglades National Park; NBS = National Biological Service (now Biological Resources Division of the U. S. Geological Survey).

Population/
Community
Region/
Habitat
Time Span/
of Record
Source of
Data
Type of
Data
Present
Ownership
SeatroutTampa Bay10 yearsFMRICPUEDEP
SeatroutFlorida Bay33 years 1NMFS
and Open
Literature
CPUENMFS
and Open
Literature
Largemouth
Bass
Lake
Okeechobee
50 yearsFGFWFC Creel
Census
FGFWFC
Wetlands
Communities
Everglades National Park10 yearsENP
and
NBS
Quant.
Samples
ENP
and
NBS
Water
Conservation
Area Canals
and Marshes
Everglades National Park 10 years
(sampled annually)
FGFWFC Relative
Abundance
(electro-
fishing)
FGFWFC
1. 6 year gap, 1967-1990

The general trend in all the data sets is one of declining fish abundances and/or taxa richness. However, given the natural variation in the populations and communities it will be difficult to detect changes in the short term (i. e. annually)

SELECTED RELEVANT REFERENCES

Dahm, C. N., K. W. Cummins, H. M. Valett, and R. L. Coleman. 1995. An ecosystem view of the restoration of the Kissimmee River. J. Restoration Ecol. 3: 225-238.

Higman, J. B. 1967. Relationships between catch rates of sport fish and environmental conditions in Everglades National Park, Florida. Proc. Gulf Carib. Fish. Inst. 19: 129-140.

Rutherford, E. S., J. T. Tilmant, E. B. Thue, and T. W. Schmidt. 1989. Fishery harvest and population dynamics of spotted sea trout, Cynoscion nebulosa, in Florida Bay and adjacent waters. Bull. Mar. Sci. 44: 108-125.

Schirripa, M. J. and C. P. Goodyear. 1992. Simulation modeling and conservation standards for spotted seatrout (Cynoscion nebulosa ) in Everglades National Park. Bull. Mar. Sci. 54: 1019-1035.

Swift, C. C., C. R. Gilbert, S. A. Bortone, and R. W. Yeager. 1986. Zoogeography \ freshwater fishes of the Southeastern United States. Pp 213-265 in: Hocutt, C. H. and E. O. Wiley. (eds.). Zoogeography of North American Freshwater Fishes. John Wiley & Sons, N. Y.

Tilmant, J. T. 1989. A history and overview of recent trends in the fisheries of Florida Bay . Bull. Mar. Sci. 44: 3-22.

APPENDIX 1

(Listing alphabetical)

Jerry Ault - Rosenstiel School of Marine and Atmospheric Science, University of Miami (305-361-4884)

Dan Canfield - Department of Fisheries and Aquatic Science, University of Florida, Gainesville (904-392-9617)

Walt Courtney - Dept. biology, Florida Atlantic Univ.

Don DeAngelis - National Biological Service, Coral Gables

Don DeSilva - Rosenstiel School of Marine and Atmospheric Science, University of Miami

Jon Fury - FL Game and Freshwater Fish Commission

Carter Gilbert, Florida State Museum, Univ. Florida (904-392-1721)

Grant Gilmore - Harbor Branch Marine Institute

Todd Hopkins Rookery Bay National Estuary

Jerry Lorenz - National Audubon Society, Travernier (305-852-5092)

Bob Michaels, Independent Monitoring Program, Florida Marine Research Institute, Department of Environmental Protection.

Frank Morello - Fl Game and Freshwater Fish Commission

Mike Murphy - Independent Monitoring Program, Florida Marine Research Institute, Department of Environmental Protection.

Mindy Nelson - National Biological Service, Dept. Environmental Science, Univ. Miami

Leo Nico - National Biological Service (904-378-8181)

Mike Robblee, National biological Service, Fl International Univ. (305-348-1269)

Joe Serafy - Rosenstiel School of Marine and Atmospheric Science, University of Miami

Mike Schmale - Rosenstiel School of Marine and Atmospheric Science, University of Miami

Tom Smith - National Biological Service, Fl International Univ. (904-378-1267)

Buck Snelson - Univ. Central Florida

Ken Sulax - National Biological Service (904-378-8181)

Jim Williams - National Biological Service (904-378-8181)


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