Spatial and Temporal Variation in the Distribution of Fishes of the LaBranche Wetlands Area of the Lake Pontchartrain Estuary, Louisiana

The LaBranche Wetlands are located along the southwestern shore of Lake Pontchartrain. During early summer of 1989 and 1990, an electroflshing survey of 6 stations In Bayou LaBranche and Bayou Trepagnier, a tributary, yielded 10,644 specimens representing 38 species in 19 families. All fishes were typical of brackish to freshwater, low gradient systems of the Gulf Coastal Plain. Members of the Lepisosteidae, Clupeidae, Fundulidae, Poecillidae and Centrarchidae were numerical dominants. Results from rotenone samples at five of the same stations by Louisiana Department of Environmental Quality in 1986, and net samples at one common site by Thompson and Verret (1980) bring the total number of species for the LaBranche Wetlands to 52. Differences in the physicochemical characters of the two bayou systems were reflected in the dissimilar faunas between the two bayous. Results from detrended correspondence analysis (DCA) and community similarity indices indicate a high degree of variance at sites within the same bayou system over time

Aquatic Studies at the Proposed George Parkhouse I Reservoir Site on the South Sulphur River in Northeast Texas

In 1997, the Texas Water Development Board identified George Parkhouse I on the South Sulphur River in northeast Texas as a potential reservoir site. This aquatic survey of a future reservoir site is designed to provide information about stream fish upstream and downstream of the proposed dam for instream flow assessment. In addition, this information will be used to identify fish assemblages and habitat associations in unchannelized as well as channelized and diverted waters for consideration of mitigation. Instream flow assessment is habitat oriented to determine the relationship between habitat availability and habitat utilization at different flows within a normal flow regime of the stream. The goals of this study were: 1) map, photograph, and assess habitats, 2) measure ambient water quality parameters, 3) report the abundance of fish of each species collected in each habitat at each of three sample sites upstream (unchannelized reach) and three sample sites downstream (channelized reach) of the proposed reservoir, 4) evaluate the relative health of sites using an Index of Biotic Integrity (Karr et al. 1986) that was regionalized for use in Texas streams (Linam and Kleinsasser 2002), and 5) identify instream habitats based on the relative abundance of fish sampled using an indicator species analysis (Dufrêne and Legendre 1997)

MESOHABITAT USE AND COMMUNITY STRUCTURE OF BRAZOS RIVER FISHES IN THE VICINITY OF THE PROPOSED ALLENS CREEK RESERVOIR

To accommodate projected increases in the demand for water, the Texas Water Development Board (TWDB) adopted the Texas Water Plan in 1997. The Texas Water Plan identifies Allens Creek as a potential reservoir site to supply water for the growing populations of Fort Bend and Brazoria counties and central Texas. Water from the lower Brazos River will be diverted to the proposed 142,982 acre-feet reservoir. This project was designed to provide information concerning Brazos River fish communities. To assist in modeling reduced instream flows 15th, 30th, and 50th percentile discharges of the summer and winter seasons were targeted for fish collections. Previous studies documenting fishes occurring near our study reach can be found in Linam et al. (1994) and Winemiller et al. (2000). Studies reporting fish communities of tidal portions and upper reaches of the Brazos River can be found in Johnson (1977), Wilde and Ostrand (1999), Winemiller and Gelwick (1999), and Ostrand and Wilde (2002). McEachran and Fechhelm (1998) lists documented species occurrences in the Brazos River watershed. This report provides information on habitat characteristics and fish assemblages across 15th, 30th, and 50th percentile discharges in summer and winter. The objectives of this project were to: (1) delineate and photodocument riffle, run, and pool mesohabitats within our study reach; (2) characterize and quantify the fishes occurring in identified mesohabitats; (3) determine indicator species of mesohabitats based on fish distributions; and (4) calculate an Index of Biotic Integrity for the reach

Espectro trófico del bagre Ictalurus punctatus (Siluriformes: Ictaluridae), en la presa Lázaro Cárdenas, Indé, Durango, México

Having the objective of determining their trophic spectrum and their variations within a year, the contents of 240 stomachs of Ictalurus punctatus (Rafinesque, 1818) were analyzed from 2006 to 2007. The items of the stomach contents were determined to the order level. The data was analyzed by different quantitative and qualitative methods. The most frequent orders were Perciforms and Atheriniforms corresponding to forage fish, along with green algae of the Charales order. Also, seven orders of invertebrates were found:  Schizodonta, Odonata, Himenoptera, Orthoptera, Hemiptera, Homoptera and Scorpionida, and two orders of plants: Poales and Fabales. The Perciform order made up almost half of the total weight of the stomach contents, followed by the Atheriniform and the Charales orders. The greatest number of empty stomachs showed up during summer and winter, while the greatest number of filled-up stomachs was found during the spring season. The quantity of food consumed during winter time was significantly lower than the amount consumed during all other seasons. The kind of food consumed during the spring, summer and autumn was mainly fish, while algae were preferred during the winter season.Se analizó el contenido de 240 estómagos de Ictalurus punctatus (Rafinesque, 1818), colectados de 2006 a 2007, con el objetivo de determinar su espectro trófico, su variación por talla y época climática. Los contenidos estomacales se analizaron en laboratorio y los organismos se determinaron hasta nivel de orden. Los datos obtenidos fueron analizados por métodos cuantitativos y cualitativos. Los órdenes más frecuentes fueron Perciformes y Atheriniformes que corresponden a peces forraje, así como algas verdes del orden Charales. Además, se encontraron otros siete órdenes de invertebrados: Schizodonta, Odonata, Himenoptera, Orthoptera, Hemiptera, Homoptera y Scorpionida, además de dos órdenes de plantas: Poales y Fabales. El orden Perciforme constituyó casi la mitad del total del peso del contenido estomacal, seguido por los órdenes Atheriniforme y Charales. En las estaciones de verano e invierno se presentó el mayor número de estómagos vacíos, mientras que en primavera se encontró el mayor número de estómagos llenos. La cantidad de alimento ingerida en la estación de invierno fue significativamente menor que en las demás estaciones. El principal alimento en primavera, verano y otoño, fueron los peces, mientras que en invierno hubo mayor preferencia por las algas

Woody Plant Encroachment into Grasslands: Spatial Patterns of Functional Group Distribution and Community Development

Woody plant encroachment into grasslands has been globally widespread. The woody species invading grasslands represent a variety of contrasting plant functional groups and growth forms. Are some woody plant functional types (PFTs) better suited to invade grasslands than others? To what extent do local patterns of distribution and abundance of woody PFTs invading grasslands reflect intrinsic topoedaphic properties versus plant-induced changes in soil properties? We addressed these questions in the Southern Great Plains, United States at a subtropical grassland known to have been encroached upon by woody species over the past 50-100 years. A total of 20 woody species (9 tree-statured; 11 shrub-statured) were encountered along a transect extending from an upland into a playa basin. About half of the encroaching woody plants were potential N(2)-fixers (55% of species), but they contributed only 7% to 16 % of the total basal area. Most species and the PFTs they represent were ubiquitously distributed along the topoedaphic gradient, but with varying abundances. Overstory-understory comparisons suggest that while future species composition of these woody communities is likely to change, PFT composition is not. Canonical correspondence analysis (CCA) ordination and variance partitioning (Partial CCA) indicated that woody species and PFT composition in developing woody communities was primarily influenced by intrinsic landscape location variables (e.g., soil texture) and secondarily by plant-induced changes in soil organic carbon and total nitrogen content. The ubiquitous distribution of species and PFTs suggests that woody plants are generally well-suited to a broad range of grassland topoedaphic settings. However, here we only examined categorical and non-quantitative functional traits. Although intrinsic soil properties exerted more control over the floristics of grassland-to-woodland succession did plant modifications of soil carbon and nitrogen concentrations, the latter are likely to influence productivity and nutrient cycling and may, over longer time-frames, feed back to influence PFT distributions

Introgression of the Florida Largemouth Bass Genome into Stream Populations of Northern Largemouth Bass in Oklahoma

Oklahoma streams and reservoirs historically contained only the northern subspecies of largemouth bass Micropterus salmoides salmoides. From 1970 to 1991 Oklahoma reservoirs throughout the state were supplementally stocked with the Florida subspecies M. s. floridanus and various intergrades of the northern and Florida subspecies. To document the effect of such introductions on the genetic structure of largemouth bass stream populations, largemouth bass throughout Oklahoma were sampled by seining. Electrophoretic analysis was carried out for loci that code the enzymes isocitrate dehydrogenase (sIDHP), aspartate aminotransferase (sAAT‐B), and superoxide dismutase (sSOD). These three loci are diagnostic for Florida largemouth bass. Analysis was also carried out for loci that code the enzymes malate dehydrogenase (sMDH‐A and sMDH‐B), phosphoglucomutase (PGM), and glucose‐6‐phosphate isomerase (GPI‐A and GPI‐B). These five loci are known to be polymorphic in largemouth bass. Overall, Florida‐ subspecific alleles were found in 4% of fish collected and at 11 % of sites that held largemouth bass. Combined frequencies of Florida‐subspecific alleles ranged from 0.00 to 0.18; highest frequencies were in the southeastern half of Oklahoma. Overall genetic variability was highest among streams of the Red River basin, and sMDH‐B* was the most variable locus. Low mean Fst values (standardized variances of allele frequencies) around 0.08 indicated little differentiation among streams. Two distance matrices based on allele frequencies (one derived from the total data set and one from a subset that excluded individuals with Florida‐subspecific alleles) showed significant correlation (approximate Mantel t‐test, P < 0.0001). This indicated that the genetic relationships among all stream populations as a whole were not significantly influenced by individuals with Florida‐subspecific alleles. Allele frequencies that were not in Hardy–Weinberg equilibrium (HWE) and heterozygote deficiencies at the sIDHP* and sAAT‐B* loci in introgressed populations suggested that the main influence of introgression was localized within individual stream systems. However, the finding of HWE in the population with the highest rate of introgression may have indicated a freely interbreeding mixture in that stream system

Modular Experimental Riffle-Pool Stream System

We describe a modular method for building a large, outdoor experimental stream system that has great flexibility for research projects in fish ecology, behavior, conservation, or management. The system has been in use for more than a decade at the University of Oklahoma Biological Station (Kingston, Oklahoma) and has been used with modification at four other research facilities in the Midwest. Here, we document the system in detail, including specifications for construction of the original system and modifications or improvements at other sites. The system uses commercially available, customized fiberglass round tank and trough units that can be configured in many different ways to create flowing pool and riffle habitats. The system appears to be a good mimic of small natural streams based on system flow rates, establishment of natural substrates and cover, stream chemistry relative to that of a natural creek, and fish behaviors. At least 39 fish species have been used successfully in 1-14-month experiments in these systems and approximately half have reproduced. The system offers great flexibility of design to experimenters, is cost effective, and may be of interest at other facilities that research basic biology, conservation, or management of stream fishes