William F. Loftus (retired) Leo Nico; Joel trexler, 2005, Influence of Hydrology on Life-History Parameters of Common Freshwater Fishes from Southern Florida.Online Links:
Quinn, J. F., Jr.; Bogan, A. E.; Coan, E. V.; Hochberg, F. G.; Lyons, W. G.; Mikkelsen, P. M.; Neves, R. J.; Roper, C. F. E.; Rosenberg, G.; Roth, B.; Scheltema, A.; Thompson, F. G.; Vecchione, M.; Williams, J. D.
The diversity of habitat types in Big Cypress presents considerable challenges to the development of a comprehensive sampling regime, as the effectiveness of any given methodology varies between habitats. To compensate for this, numerous techniques were employed during this study. A variety of fish traps have been used extensively, as well as electrofishing gear, gill nets, cast nets, dip nets, and angling.
The location of each sampling site was recorded as universal transverse mercator (UTM) coordinates using a Garmin Etrex Vista GPS.
Project personnel collected and curated representative vouchers for all captured species whenever practical. Specimens too large to effectively preserve have been documented photographically using a digital camera. Vouchers have been collected independently for each habitat type sampled. Additionally, to ensure complete spatial coverage of the preserve, vouchers of each species have been collected from the north, central, and southern regions of Big Cypress. Information regarding each voucher was entered into the project Access database, and each was assigned a unique identifier to link with related sampling information. Voucher collection is an ongoing process and will continue for the duration of the study. Upon completion of this project, vouchers will be transferred to an NPS-identified repository.
Personnel from The National Audubon Society are collaborators in this project.
305 348-1966 (voice)
305 348-4032 (FAX)
trexlerj@fiu.edu
The objectives of this project are to establish age-size relationships for 11 species of fishes, construct life-tables, study reproductive phenology and fecundity, and apply the data to simulation models and to field data time-series. Work on this project began in late 1999 and is divided into large-fish and small-fish segments.
A variety of fish traps were used extensively as well as electrofishing gear, gill nets, cast nets, dip nets, and angling.
Non-indigenous species: Spotted tilapia (Tilapia mariae) - an abundant and widespread species;
Native species: Florida gar (Lepisosteus platyrhincus) ÷ abundant predator on other fish and crustaceans; Yellow bullhead (Ameiurus natalis) ÷ most abundant catfish, and also a predator; Warmouth (Lepomis gulosus) - Common sunfish that preys o1i-vrayfish, shrimp, and fish; Spotted sunfish (Lepomis punctatus) ÷ Abundant sunfish that feeds on invertebrates.
Samples of these species from canal habitats, where they are very abundant at drier times of year, will be preserved in formalin for gonadal examination, with another sample saved in ethanol to avoid damage to the calcium-rich hard tissues used for aging. We anticipate that it will be more difficult to collect adequate sample sizes of large fish at high-water times when they disperse from canals into wetlands. Dr. Nico plans to put in more effort at those times, and to supplement his collections with previously preserved specimens in our collections. Collections will be made quarterly throughout the year.
For the small-bodied species, Dr. Trexler and I plan to concentrate on the following species that inhabit marsh habitats, and about which little life-history information is known. Age and growth information has been collected for some of the species (Haake and Dean 1983), but reproductive characteristics require study. These species, in total, represent the most numerous species in the marshes:
Age and Growth data ÷ Sailfin molly (Poecilia latipinna); Flagfish (Jordanella floridae); and Spotted sunfish (Information specifically on marsh populations of spotted sunfish is needed).
Reproduction/phenology ÷ Least killifish (Heterandria formosa); Bluefin killifish (Lucania goodei); Golden topminnow (Fundulus chrysotus); Eastern mosquitofish (Gambusia hoibrooki); Sailfin molly; and Flagfish.
We plan to use existing archived collections of fishes from our extensive spatial and temporal marsh studies for reproductive analyses of fecundity, size of maturity, seasonality of reproduction, and sex ratios. A companion effort to sample larval fish in the wetlands will provide data for recruitment patterns and effort. The preserved collections will be supplemented during routine sampling five times per year by fresh collections of fishes, which will be frozen or preserved in alcohol for otolith (earbone) analysis. The proposed work will include counts of daily rings on otoliths, and size-frequency analyses to create an age-at-size table for each species, and to estimate growth in different seasons and along the hydroperiod gradient. These studies will allow us to construct life-tables for the species under different conditions in the Everglades. Data from several years are needed because each year in the Everglades can be idiosyncratic. We plan to collect field data from at least two years, and supplement those data with previously collected samples to expand the temporal scope of the study.
Small-Bodied Species
For the small-bodied species, Dr. Joel Trexler of Florida International University and his students will concentrate on the following species that inhabit marsh habitats and, about which, little life-history information is known. Age and growth information has been collected for some of the species (Haake and Dean 1983), but reproductive characteristics require study. These species, in total, represent the most numerous species in the marshes.
Age and Size Relationships to Estimate Growth Rate - We will establish age-to-size relationships for three marsh fish species: sailfin molly (Poecilia latipinna); flagfish (Jordanella floridae); and spotted sunfish (Information specifically on marsh populations of spotted sunfish is needed). These relationships will be estimated at one representative short (at Shark Valley) and one representative long hydroperiod location (at Shark River Slough). The proposed work will include counts of daily rings on otoliths, and size-frequency analyses to create an age-at-size table for each species, and to estimate growth in two different seasons. These studies will allow us to construct life-tables for the species under different conditions in the Everglades.
We will conduct experimental rearing of these fishes to a known age in field cages in anticipation of otolith removal and interpretation. In past efforts, this approach has demonstrated a very high fidelity of daily ring deposition in sailfin mollies up to the age of 21 days. This result needs to be repeated and expanded to other species. For several reasons, ring deposition becomes less easily interpreted as fish age. These include that the thickness of ring width decreases with age making them increasingly difficult to discriminate, disease and physiological stress unrelated to age also affect deposition. With livebearing fishes it is possible to place neonates into the cages and raise fishes of known age. However, with spotted sunfish and flagfish it may be necessary to take fish of unknown age and mark their otoliths with tetracycline. This is accomplished by emersing the fish in a tetracycline solution that intercalates with the calcium deposited at that time. The rings deposited under these conditions glow under ultraviolet light. The fish is maintained in a cage for a period of time after marking and prior to otolith removal and analysis. The number of rings deposited after the tetracycline dip may then be callibrated with the time known to have passed. This is especially useful to calibrate aging in adult fishes.
Reproduction/phenology - We will document reproductive phenology and output in six marsh fish species: least killifish (Heterandria formosa); bluefin killifish (Lucania goodei); golden topminnow (Fundulus chrysotus); eastern mosquitofish (Gambusia holbrooki); sailfin molly; and flagfish. We will attempt to use existing archived collections of fishes from the extensive spatial and temporal marsh study collections for reproductive analyses of fecundity, size of maturity, seasonality of reproduction, and sex ratios. If sample sizes are inadequate, supplemental samples will be collected. A companion effort to sample larval fish in the wetlands will provide data for recruitment patterns and effort. The preserved collections will be supplemented during routine sampling five times per year by fresh collections of fishes, which will be frozen or preserved in alcohol for otolith (earbone) analysis. Estimates of reproductive biology will follow Trexler (1985) for livebearing species, and Heins et al. (1986) and Heins (1995) for egg-laying species.
Data from several years are needed because each year in the Everglades can be idiosyncratic. Field data will be collected for a minimum of two years, and supplemented with previously collected samples to expand the temporal scope of the study.
Large-Bodied Species
Non-indigenous species: Spotted tilapia (Tilapia mariae) - an abundant and widespread species. Native species: Florida gar (Lepisosteus platyrhincus) - abundant predator on other fish and crustaceans; Yellow bullhead (Ameiurus natalis) - most abundant catfish, and also a predator; Warmouth (Chaetobryttus gulosus) - Common sunfish that preys on crayfish, shrimp, and fish; and Spotted sunfish (Lepomis punctatus) - Abundant sunfish that feeds on invertebrates.
Samples of these species from canal habitats, where they are very abundant at drier times of year, will be made by Nico during periodic electrofishing trips to south Florida from Gainesville. Specimens will be preserved in formalin for gonadal examination, with a second sample will be saved in ethanol to avoid damage to the calcium-rich hard tissues used for aging. We anticipate that it will be more difficult to collect adequate sample sizes of large fish at high-water times when they disperse from canals into wetlands. Dr. Nico plans to put in more effort at those times, and to supplement his collections with previously preserved specimens from archived existing collections. Collections will be made quarterly throughout the year. The analytical procedures will be similar to those described for the small-bodied species, except that none of the large species appear to be fractional spawners. This makes the estimate of lifetime fecundity somewhat less problematic. For these long-lived species, we do not think it feasible to use daily otolith rings for aging because it becomes difficult to do so because the rings become indistinct. We will investigate this further in the pilot study, but may follow the usual procedure for large fishes of reading annular rings. With that, of course, we will have to validate the timing and frequency of "annualar" ring formation through marking of captive fishes.
1. Inventory of Freshwater Fish Species within the Big Cypress National Preserve, with emphasis on methods testing to design a long-term aquatic biota sampling program
The goal of this project in FY03 is to inventory the freshwater fish in the Big Cypress National Preserve, and simultaneously test sampling methods and designs for a long-term aquatic biota research program for the Preserve. A major ecosystem of the South Florida area, the Big Cypress Swamp, is poorly understood in biological terms. The Department of Interior is responsible for management of most of this system, which is part of the Everglades Restoration Program (CERP). We propose to describe large and small fish and macro-invertebrate ecology in representative habitats of the Swamp in a multiyear study to provide basic inventory information on Swamp communities and ecological data for use in simulation models. The models will be used to plan and evaluate restoration actions during CERP. Presently, inappropriate data from the Everglades are used in the Swamp model.
2. Life-History Characteristics of Common Everglades Fishes
In the final year of this task, we will complete the laboratory analysis of additional and existing samples to assess the biology of the flagfish (Jordanella floridae) and bluefin killifish (Lucania goodei). The life-histories of the flagfish and bluefin killifish will be characterized from existing samples collected at two sites in Everglades National Park that represent different hydroperiod conditions. The analysis of previously collected samples of other large- and small-bodied species will be completed and the results written for publication Because we were unable to collect adequate samples of yellow bullhead catfish (Ameiurus natalis) from the canal sites, we plan to work with our cooperator, Dr. Trexler, to collect samples from marsh habitats for analysis. Dr. Trexler has an ongoing sampling program in the Everglades marsh during which he can collect the samples we need to finish this study component. He can collect samples five times during the year to provide samples from different seasons.
Age-Size relationship: Small fishes collected the hydroperiod study sites in the Everglades marsh are being analyzed for otolith annular counts. The number of fish examined has been determined by the pilot study and is consistent with standard methods for this kind of work. Maximum life expectancy is being estimated by the estimating the ages of large specimens of the two species from our collections. In the large-fish segment, we are analyzing the results of our work with Florida gar and warmouth sunfish, while completing the work begun with spotted tilapia aging. Statistical analysis of the data has begun now that all data have been collected and error-checked. We have done preliminary work with yellow bullhead aging to determine the best tissue for this purpose and we proceed with this work once we have specimens in hand.
Reproductive Biology. Our estimates of reproductive phenology and fecundity in egg-laying fishes have required the dissection of female fish to determine the number and developmental stage of ova. In addition, we have been recording the weight of female fish and of their ovaries for calculations of reproductive allocation. Female flagfish are batch spawners that produce a brood of eggs in discrete spawning events, while bluefin killifish are fractional spawners that release a small number of eggs on a routine basis. These two different modes of reproduction have posed challenges to life-history description. The time interval between breeding bouts and the relationship between egg counts from preserved females and actual number of eggs laid must be determined for flagfish. For bluefin killifish, we must estimate the daily egg production, and the distribution of female reproductive lifespans. To satisfactorily obtain these parameters for these two fishes, we have reared these fishes in mesocosm tanks and aquaria, and harvested eggs from nests (flagfish) or artificial spawning substrates (bluefin killifish
In the large-fish segment, we will complete analysis of reproduction in Florida gar and other large-bodied species by dissection, gonadal examination, and preparation of a gonadal-somatic index for each species. We have also performed a literature review to determine reproductive parameters from other populations of these species. We will perform reproductive analyses with yellow bullheads once we receive specimens.
Person who carried out this activity:
305 348-1966 (voice)
305 348-4032 (FAX)
trexlerj@fiu.edu
Loftus, William F., 2000, Inventory of the fishes in Everglades National Park: Florida Scientist v. 63, n.1, Florida Academy of Sciences, Orlando, FL.
Lorenz, J. J. McIvor, C. C.; Powell , G. , 1997, A drop net and removable walkway used to quantitatively sample fishes over wetland surfaces in the dwarf mangroves of the southern Everglades: Wetlands v. 17, n. 3, p. 346-359, Society of Wetlands Scientists, McLean, VA.Online Links:
The full article is available via journal subscription or single article purchase. The abstract may be viewed on the website below.
Duever, M. J. Carlson, J. E.; Meeder, J. , 1979, Resource inventory and analysis of the Big Cypress National Preserve: Center for Wetlands, UF-Gainesville and National Audubon Society, Naples, FL.
Loftus, W. F. Eklund, A. M., 1994, Long-term dynamics of an Everglades fish community: St. Lucie Press, Delray Beach, FL.
S. Davis and J. C. Ogden, editors
Trexler, J. C. Loftus, W. F., 2001, Analysis of relationships of Everglades fish with hydrology using long-term databases from Everglades National Park: Florida International University, Miami, FL.
Trexler, J. C. Loftus, W. F.; Jordan, F.; , 2001, Ecological scale and its implications for freshwater fishes in the Florida Everglades: CRC Press, Boca Raton, FL.
J. W. Porter and K. G. Porter, editors
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Big Cypress National Preserve Fish Inventory & Monitoring Data
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