Orange Lake Research Articles

Nest Sites Used by Radio-Tagged Largemouth Bass in Orange Lake, Florida

The bottom substrates of many Florida lakes are predominantly unconsolidated organic matter with only limited areas of firm substrate typically used for spawning by largemouth bass Micropterus salmoides. The purpose of this study was to locate by radiotelemetry and describe the nest sites of male Florida largemouth bass Micropterus salmoides floridanus in a lake with essentially no firm inorganic substrate. We located 20 nests during the 1983 and 1984 spawning seasons: 13 in spatterdock Nuphar luteum (25% of the available habitat), 5 in emergent grasses Paspalidium geminatum and Panicum hemitomon (1% of the available habitat), and 2 in smartweed Polygonum hydropiperoides (10% of the available habitat). No nests were found in open water (64% of the available habitat). Observed nests were constructed on rhizomes in the spatterdock habitat or on firm detritus in the emergent grass and smartweed. Spatterdock, due to its abundance, was the most extensively used nesting habitat, but selectivity for nest sites was higher for the less abundant emergent grass. Although all nests were associated with vegetation, firm bottom or above-bottom substrate appeared to be important in nest-site selection.

Effects of Aquatic Macrophytes on Benthic Macroinvertebrates in Two Florida Lakes

Abstract Greater numbers of invertebrate taxa were collected in vegetated than open water (unvegetated) communities in two Florida lakes. Differences in macroinvertebrate density and biomass were found among communities and sampling periods for most prevalent taxa in both lakes. In Henderson Lake, density of benthos was highest in the open water community due to the abundance of Chaoborus, and biomass of benthos was highest in the Panicum and open water communities due to the abundance of molluscs. In Orange Lake, density and biomass of benthos were higher in the vegetated than in the open water communities. Bottom substrate was an important determinant of benthic invertebrate abundance; density and biomass of benthos were greater in communities with firm substrata than in communities with soft organic substrata. When communities with similar substrata were compared, benthic invertebrates were more abundant in vegetated than in open water communities.

Survival of Young American Alligators on a Florida Lake

A capture-recapture study was conducted on Orange Lake, Florida, from 1979 through 1984 to estimate survival rates of young in an American alligator (Alligator mississippiensis) population. Hatchlings remained together in sibling groups (pods) for at least their 1st year and then began to disperse during their 2nd spring and summer. Mortality through mid-November of their 1st year was negligible. Jolly-Seber (JS) survival estimates of hatchlings for 6 and 12 months were 76 and 41%, respectively. The 2-year JS estimate for the 1980 cohort was 8%. Minimum-Known-Alive (MKA) survival values were 72 and 46% of JS estimates for 6 months and 1 year of age. Survival during the 2nd 6 months of life (spring-summer) tended to be lower than survival during the 1st 6 months (fall-winter). J. WILDL. MANAGE. 51(4):931-937 Generally, crocodilians are secretive; they quickly learn to avoid humans and frequently inhabit areas that are difficult to access. These factors render them difficult subjects for survival studies. Therefore, most references to survival rates have been based on casual observations (Neill 1971), small samples (McIlhenny 1935, Modha 1967, Murphy 1977, Webb et al. 1977), or interpretation from population size structures (Chabreck 1966, Graham 1968, Nichols et al. 1976, Webb et al. 1983, Taylor and Neal 1984). Recent mark-recapture studies have attempted to estimate survival rates, using MKA estimates, for American alligators (Deitz 1979) and saltwater crocodiles (Crocodylus porosus) (Messel et al. 1981:390-394) <2 years of age. The MKA survival rate estimator is used extensively by crocodilian researchers because of its simplicity. However, as its name implies, MKA estimates are biased (Nichols and Pollock 1983). Survival rates are an important component of population models (Nichols 1987), especially when models are intended for use in predicting population responses to harvest strategies. Furthermore, growing emphasis on early age-class harvest will make juvenile survival rates increasingly important when evaluating the suitability of various alligator populations for egg or hatchling removal. Our work on Orange Lake, Florida, provided an opportunity to conduct long-term mark-recapture studies on a relatively abundant and accessible population of alligators. Our primary objectives were to estimate survival rates of juvenile alligators using the JS estimator (Jolly 1965, Seber 1965) and to determine the relationship between the JS and MKA estimators. We are grateful to D. C. Deitz, T. M. Goodwin, J. E. Thul, W. C. Maahs, M. L. Jennings, M. F. Delany, and H. F. Percival for field assistance in this study. We also thank H. F. Percival, M. F. Delany, T. G. O'Brien, C. T. Moore, nd M. L. Jennings for providing valuable comments and T. L. Steele for typing this manu-

Influence of Hydrilla on Harvestable Sport-Fish Populations, Angler Use, and Angler Expenditures at Orange Lake, Florida

Abstract An infestation of hydrilla Hydrilla verticillata caused an 85% reduction in angler effort at Orange Lake, Florida, in 1977 when plant coverage exceeded 80% of the lake. Nonlocal anglers were only 3% of the total number of anglers fishing the lake in 1977, but were 37% of the anglers during 1978 and 1979, when hydrilla coverage was less than 19%. Although angler use of Orange Lake was greatly reduced during the peak 1977 hydrilla infestation, the number of fish caught per hour during 1977 was equivalent to or greater than that of all other study years for all species of sport fish. The almost complete plant coverage did not lower the population of harvestable largemouth bass Micropterus salmoides or black crappie Pomoxis nigromaculatus. Numbers of harvestable bluegill Lepomis macrochirus and redear sunfish Lepomis microlophus were, however, negatively correlated with hydrilla coverage. Reduction in angling caused a 90% loss in revenue from the Orange Lake sport fishery that is valued at approximat...

A survey of Culicoides midges (Diptera: Ceratopogonidae) associated with cattle operations in Florida, USA.

Species composition and seasonal prevalence of Culicoides spp. associated with cattle at 5 sites in peninsular Florida, USA, were studied from April 1980 to April 1982. Based on light-trap data, C. insignis was the most common species occurring at Orange Lake, Ona, and Belle Glade, while C. variipennis was the predominant species at the site near Bell and also at Brooksville. Seasonal peaks of C. variipennis populations occurred in the spring and early summer, while C. insignis populations reached maximum levels in late summer and fall. During the 2-year study, 115,916 specimens representing 23 species were identified from the 5 peninsular sites. The fewest Culicoides species (6) were taken at Belle Glade and the most (17) were taken at Orange Lake.

Spacing Patterns in Alligator Nests

The pattern of alligator nest location is measured for four consecutive years across a set of quadrats on Orange Lake (Alachua County) Florida. The nests are clumped, and this clumping is evident even given controls for habitat heterogeneity. The recent recovery of Alligator mis- sissippiensis from endangered status has generated a significant renaissance of research into this reptile's biology. It is particularly important for biologists and management specialists alike to learn what factors might limit the density of alligator populations. For over 20 years workers in Louisiana have known that

Variable photosynthesis/photorespiration ratios in Hydrilla and other submersed aquatic macrophyte species

Hydrilla verticillata plants collected from Orange Lake in Florida during the summer exhibited higher net photosynthetic rates and lower photorespiratory and dark respiratory rates than plants collected during the winter when measured at a standard temperature of 25 °C. Similar seasonal shifts in the CO2 compensation point, ranging from 17 μL CO2/L in summer to 90 in winter, occurred in Hydrilla from three geographically distinct lakes in Florida. Incubation of Hydrilla and five other submersed angiosperms under a high temperature (27 °C day) and long photoperiod (14 h) reduced the CO2 compensation point to less than 20. A continuously high CO2 concentration of 5000 μL/L (gas phase) prevented the decline in the CO2 compensation point, whereas 300 μL/L induced it. Lake-grown and chamber-grown Hydrilla with low photorespiratory capacity, as determined by low CO2 compensation points, showed elevated phosphoenolpyruvate carboxylase activity (239 versus 33 μmol/mg Chl per hour). Diurnal gas-exchange measurements at 300 and 3000 μL CO2/L (gas phase) demonstrated that low photorespiration Hydrilla exhibited net CO2 fixation in the dark at the higher CO2 level, probably via the elevated phosphoenolpyruvate carboxylase activity. Only Hydrilla with low CO2 compensation points exhibited net dark fixation and then only during the night period. The excretion of 14C-organic compounds was only 3% of the 14CO2 light fixation rate and thus too low to account for the reduced photorespiration. The potential to alter the photosynthesis/photorespiration ratio appears ubiquitous among submersed freshwater macrophytes. This ratio change to a low photorespiratory capacity, and the induction of a dark fixation capacity, would aid the carbon economy under summer daytime conditions of low inorganic carbon and high O2, where photorespiratory CO2 loss would otherwise be substantial.

Efficiency of Rotenone Sampling with Large and Small Block Nets in Vegetated and Open-Water Habitats

Abstract The sampling effectiveness of rotenone applied within large (0.41 hectare) and small (0.08 hectare) blocknetted areas was compared at open-water and vegetated sites in Orange Lake, Florida. Eighteen fish species were collected within the large nets and 21 species within the small nets; 16 species were common to both nets. Total fish biomass (kg/hectare) and abundance (number/hectare) estimates did not differ significantly (P ≤ 0.10) between areas in either open-water or vegetated habitats; abundance estimates (number/hectare) did not differ between large and small open-water areas. Significantly higher abundance estimates were obtained in the smaller nets in vegetated habitats due to more efficient pickup of small fish. For larger size game fish, total abundance, biomass, and individual species estimates were not significantly different between sample areas in either habitat. The smaller experimental nets provided inventories of fish populations that were as accurate as those from large-area samp...

Fish Harvest Resulting from Mechanical Control of Hydrilla

Mechanical harvesting of the submersed weed hydrilla, Hydrilla verticillata (L.F.) Royle, in Orange Lake, Florida entangled fish in the cut vegetation resulting in their disposal with the weeds on shore. Three block-net samples in dense hydrilla indicated fish standing crops (mean ± SD) of 205,000 ± 35,000 fish/hectare and 460 ± 30 kg/hectare. The estimated loss of fish to mechanical harvesting represented 32% of fish numbers and 18% of fish biomass. Fish most susceptible to mechanical removal with hydrilla were juvenile sportfish and smaller species. The monetary replacement value of the fish lost was estimated at over $6,000/hectare.

Predicting fluxes of latent and sensible heat of lakes from surface water temperatures

Wind velocity, air temperature, and humidity fluctuations were measured over Orange Lake, Florida, using an ultrasonic anemometer‐thermometer and Lyman alpha humidity sensor. Latent and sensible heat fluxes were calculated from the data using the eddy correlation technique. Lake temperature at a 2.5‐cm depth was measured in order to compare eddy correlation results with fluxes and the Bowen ratio predicted by the formulae of Hicks (1975) and Priestley and Taylor (1972) in which temperature is the sole parameter. Bowen ratio results were in good agreement with the formulations of Hicks (1975) and Priestley and Taylor (1972) if property values were evaluated at a temperature intermediate to the lake and 10‐m air temperature. Disagreement with fluxes predicted by Hicks (1975) indicates that such formulations are inadequate for short‐term flux evaluations under the meteorological conditions in which surface water temperature is changing with time.

Origin and Hydrology of Orange Lake, Santa Fe Lake, and Levys Prairie Lakes of North-Central Peninsular Florida

The water table in the Ocala limestone is the local base level of erosion in southeastern Alachua County. The basin of Orange Lake has developed in that area as a result of the erosion of insoluble sediments of the plateau and solution of the Ocala limestone to that water plane. Usually, the lake fluctuates with the water table. The lake water sometimes becomes perched when impervious lake sediments prevent loss of water through the lake bottom and solution channels into the underlying permeable limestone. This situation may develop when the water table falls during periods of diminished rainfall. The recent low stand of water in Orange Lake was caused by factors in addition to the prevailing drought conditions. The regional water table in the limestone fell below the lake bottom. This resulted in sufficient hydrostatic pressure to unlodge sediments plugging a sinkhole. The lake level subsequently fell considerably, due in large part to the quantity of water discharged into the underlying limestone through the sink. Santa Fe Lake, located in northeastern Alachua County, is largely sealed off from the principal aquifer, the Ocala limestone, by Pleistocene clayey sands and relatively impervious sediments of the Hawthorne formation. Sufficient rain water from the youthful plateau of pine-palmetto flatlands, swamps, and marshes slowly drains and seeps into the lake to largely offset losses from evaporation, transpiration, and seepage even during drought periods. In addition to discharge by seepage in an eastward direction through surficial sands, overflow into a swampy area north of the lake occurs at times of unusually high water. These conditions result in a more stabilized lake level than that of Orange Lake. Even though the Hawthorne formation and surficial sands are superimposed on the Ocala limestone in the region of Levys Prairie lakes, that part of Putnam County is a recharge area of the Eocene limestones. In this region the upper part of the Hawthorne formation contains considerable carbonate. Solution of both Hawthorne sediments and the Ocala limestone has resulted in slumpage that breached the superimposed, relatively impervious sediments, thus facilitating and, in some cases, allowing free downward movement of water to the principal aquifer, the Ocala limestone. A sink is known to connect one Levys Prairie lake with underlying pervious sediments. The lakes fluctuate markedly with periods of drought and abundant rainfall. The lower parts of this prairie surface coincide approximately with the piezometric surface of the water in the Eocene limestones. It appears that the piezometric surface in this area of subsurface drainage is acting as a temporary base level of erosion despite the surficial insoluble sediments. The topography contrasts markedly with the area of Orange Lake from which most of the insoluble materials of the plateau have been eroded away.

Food of the Black Crappie Pomoxis Nigro-Maculatus (LeSueur), in Orange Lake, Florida

Orange Lake in north central Florida has an area of approximately 14,000 acres and is surrounded by extensive marshes. During a 12-month period, stomach contents of 902 black crappie (Pomoxis nigro-maculatus) ranging in size from 31 to 291 millimeters, standard length, were analyzed. The frequency of occurrence of various food organisms, seasonal trends in the consumption of food items, and the average volume of food per stomach are presented. Gizzard shad are the most important food item of the adult crappie except during the spring months of February, March, and April when their frequency is exceeded or equalled by Malacostraca. In summer and fall crappies feed largely upon fishes and, to a lesser extent, upon Malacostraca, dipterous larvae, pupae and adults, and Entomostraca. During the winter months fishes constitute the main food of the crappie, all other food items occurring in less than 50 percent of the stomachs. The chief food of young crappies is Entomostraca. The consumption of larger organisms increases as they attain larger size. During breeding season male crappies eat approximately 33 percent more malacostracans and 33 percent less fish than females.

Central Florida Farm Landscape

F oROM Tampa northward to the Georgia line stretches the pitted limestone backbone of Florida, the Florida karst. Long recognized as a region distinct from the Gulf hammocks (hardwood forests) to the west and from the flatwoods to the east, this area includes the highest points in peninsular Florida. The surface may be briefly described as a very subdued karst, in which the usual forms are shallow, concave basins and low, rounded hills, a thick cover of sand masking any irregularities which might otherwise appear. Small streams are almost entirely lacking, but there are a few larger streams, a number of small permanent lakes, and, in many of the solution depressions, a large number of intermittent ponds. Nearly all of the higher land is covered with long leaf pine and the lower parts of the basins are in savanna, hardwood, or swampy vegetation. In central Florida, south of Orange Lake (Figure 1), the region was settled less than a century ago. It was first used for grazing in the savannas or woodland pastures, later for the growing of cotton, sugar cane, and corn, and more recently for citrus fruits. Since the end of the last century it has produced turpentine, lumber, and phosphate. Most of these industries survive, having undergone many fluctuations, especially in certain localities, as indicated in the following descriptions. Three small areas, Lecanto, Blanton, and Citra will be described in detail to illustrate the development of farm types under varying natural conditions. LECANTO