Timothy H. Bonner

Changes in the Canadian River fish assemblage associated with reservoir construction

ABSTRACT The fish assemblage of the Canadian River in Texas historically was dominated by Hybognathus placitus and Notropis girardi. These species represented > 90% of fishes collected from the Canadian River in 1954–1955. Construction of two reservoirs on the Canadian River in the 1960s (Ute Reservoir, New Mexico, 1962; Lake Meredith, Texas, 1965) altered hydrologic conditions in the river and affected the fish assemblage. Downstream from Ute Reservoir, mean annual discharge decreased by about 38% after impoundment, but H. placitus, N. girardi, and other mainstem species still dominate the assemblage. Downstream from Lake Meredith, mean annual discharge decreased by 76% and the historic mainstem fish assemblage has been almost completely replaced by species that formerly were restricted to tributary streams. The magnitude of post-impoundment changes in the fish assemblage of the Canadian River appears to be related to the degree that discharge has declined, especially during the spawning season.

Effects of Turbidity on Prey Consumption by Prairie Stream Fishes

Abstract Reduced suspended-sediment loads (i.e., turbidity) in many Midwestern prairie rivers have been hypothesized as contributing to the replacement of species that historically occupied highly turbid main-channel habitats by visually feeding species that are competitively superior in less-turbid waters. We examined the relationship between prey consumption and turbidity for six fish species from the Canadian River (New Mexico, Oklahoma, and Texas) and found experimental support for this hypothesis. Among species adapted to highly turbid main-channel habitats, we found that prey consumption by the peppered chub Macrhybopsis tetranema and flathead chub Platygobio gracilis was unaffected (P > 0.12) by elevated turbidity, whereas prey consumption by the Arkansas River shiner Notropis girardi was reduced (P < 0.01). Among species characteristic of less-turbid habitats, prey consumption by the emerald shiner N. atherinoides, red shiner Cyprinella lutrensis, and sand shiner N. stramineus was reduced (P < 0.0...

Relationships among Swimming Ability, Current Velocity Association, and Morphology for Freshwater Lotic Fishes

Abstract We determined swimming ability for 37 warmwater stream fishes in Texas and Louisiana and assessed relationships among swimming ability, habitat selection, and fish morphology. Mean absolute speeds (cm/s) were 17.8–81.9 cm/s for Cyprinidae, 50.9 cm/s for Characidae, 70.0 cm/s for Ictaluridae, 33.0 cm/s for Cichlidae, 40.0 cm/s for Percidae, 30.7–43.4 cm/s for Cyprinodontidae, 30.2 cm/s for Atherinidae, 15.7–18.6 cm/s for Poeciliidae, and 23.4–40.5 cm/s for Centrarchidae. Absolute swimming speeds were correlated (P < 0.01) to reported habitat descriptions (i.e., sloughs, lakes, streams, and rivers) of fishes. Absolute swimming speeds also were good predictors of spatial (i.e., runs, pools, and riffles) distributions of fishes from Independence Creek, Texas (P = 0.03), and Banita Creek, Texas (P = 0.06). Multivariate ordination of nine morphological attributes identified the linear combination of relative body depth, dorsal fin length, and caudal span width as an adequate predictor (P < 0.01) of swi...

Occurrence and amount of microplastic ingested by fishes in watersheds of the Gulf of Mexico.

Ingestion of microplastics by fishes could be an emerging environmental crisis because of the proliferation of plastic pollution in aquatic environments. Microplastics in marine ecosystems are well documented, however only one study has reported percent occurrence of microplastics in freshwater fishes. The purpose of this study was to quantify the occurrences and types of microplastics ingested by fishes within several freshwater drainages of the Gulf of Mexico and an estuary of the Gulf of Mexico. Among 535 fishes examined in this study, 8% of the freshwater fishes and 10% of the marine fishes had microplastics in their gut tract. Percentage occurrence of microplastics ingested by fishes in non-urbanized streams (5%) was less than that of one of the urbanized streams (Neches River; 29%). Percent occurrence of microplastics by habitat (i.e., benthic, pelagic) and trophic guilds (herbivore/omnivore, invertivore, carnivore) were similar. Low but widespread occurrences among drainages, habitat guilds, and trophic guilds indicate proliferation of plastic pollution within watersheds of the Gulf of Mexico, but consequences to fish health are unknown at this time.

Admixture Analysis of Florida Largemouth Bass and Northern Largemouth Bass using Microsatellite Loci

Abstract Microsatellite DNA variation was examined at 11 loci in five populations of Florida largemouth bass Micropterus salmoides floridanus (N = 175) and eight populations of northern largemouth bass M. s. salmoides (N = 249). Distinct allele frequencies with 33 private alleles between subspecies (threshold frequency, ≥0.05) and 19 private alleles among three geographic regions distinguished between Florida largemouth bass and northern largemouth bass as well as between northern largemouth bass from northern and southern latitudes in North America. Variation at microsatellite loci also provided sufficient resolution to discriminate among some populations within regions. Allele frequencies indicated that of 37 trophy bass (defined here as fish weighing 5.90 kg or more) donated to the Texas Parks and Wildlife Department (TPWD) between 2004 and 2005, all had more than 50% Florida largemouth bass influence with ancestry genetically similar to that of populations sampled in western Florida. Some fish (N = 24...

Interactive Effects of Environmental Variability and Military Training on Stream Biota of Three Headwater Drainages in Western Louisiana

Abstract We collected fishes and macroinvertebrates seasonally from eight headwater streams in three different drainage basins (the Red, Calcasieu, and Sabine rivers) crossing Peason Ridge Training Area in west-central Louisiana. Peason Ridge is part of the Fort Polk military training facility. We used multivariate analyses to test the effects of physical variables (i.e., current velocity, depth, and substrate), time (seasonal variability), drainage basin, and military training activities on assemblage structure. Tributaries of the Red River had the highest gradient and were predominated by shallow, swift-flowing runs with sandy substrates. Southern tributaries of the Calcasieu and Sabine rivers were of lower stream gradient and contained deep, sluggish runs and pools with large amounts of woody debris and silt. Fish assemblages were structured primarily by military training and drainage basin. Faunal differences among drainage basins probably reflect differences in stream gradient. Fish assemblages in tr...

Trophic ecology of a nonnative population of suckermouth catfish (Hypostomus plecostomus) in a central Texas spring-fed stream

Introduced suckermouth catfishes (Family Loricariidae) are now established in a number of spring-influenced streams in North America but their impacts on native biota are not well documented. Purposes of this study were to quantify gut contents of the loricariid Hypostomus plecostomus from the San Marcos River in central Texas and to evaluate the role of H. plecostomus in the San Marcos River food web using stable isotope analysis. Gut content analysis indicated that H. plecostomus (N = 36) primarily consumed amorphous detritus (87% in biovolume), filamentous red algae (5.4%), and picoplankton (4.1%). Macrophytes, macroinvertebrates, and fish eggs were not found in gut contents. Stable isotopes demonstrate that H. plecostomus occupies a trophic position indicative of an herbivore and likely utilizes detritus of algal origin. The results from our study suggest that large populations of H. plecostomus in the San Marcos River may directly compete with several native herbivorous fishes and may be disrupting trophic flows and nutrient cycling in spring-influenced streams of central and west Texas.

Effects of Temperature on Egg Production and Early Life Stages of the Fountain Darter

Abstract Studies were conducted to determine the effects of water temperature on egg and larval production, larval survival, and juvenile growth of the endangered fountain darter Etheostoma fonticola. Adult fish were exposed to water temperatures of 14, 17, 20, 23 (control), 25, 27, and 29°C for 33 d. Egg production was significantly higher (P ≤ 0.05) for fish held at 14, 17, 20, 23, and 25°C than for fish held at 27 and 29°C. Percent hatch was significantly higher (P ≤ 0.05) at 17, 20, and 23°C than at 14, 25, 27, and 29°C. Larval production was significantly higher (P ≤ 0.05) at 14, 17, 20, and 23°C than at 25, 27, and 29°C. Estimated low and high temperatures to produce 50% mortality of larvae (24–72 h old) over a 24-h period were 3.8 and 31.9°C, respectively. Low survival and substantial variation in growth of controls prevented a meaningful assessment of temperature effects on juvenile growth.

Status of an Introgressed Guadalupe Bass Population in a Central Texas Stream

Abstract Introductions of nonnative smallmouth bass Micropterus dolomieu into central Texas streams resulted in introgressive hybridization with an endemic allopatric congener, the Guadalupe bass M. treculii. The objectives of this study were to use the variation at 14 microsatellite DNA loci to examine the frequencies of Guadalupe bass, smallmouth bass, and their hybrids 10 years after supplemental stockings of Guadalupe bass in the Blanco River. Genetic analysis identified 40% of individuals as smallmouth bass, 51% as smallmouth bass × Guadalupe bass hybrids, and 9% as other Micropterus hybrids. Pure Guadalupe bass were not collected. Despite supplemental stocking, the frequency of pure Guadalupe bass appears to have declined in the Blanco River in the past 10 years. These results emphasize the need for a current survey of the genetic status of the species throughout its native range.

First Record of Bothriocephalus acheilognathi in the Rio Grande with Comparative Analysis of ITS2 and V4-18S rRNA Gene Sequences

Bothriocephalus acheilognathi is an introduced tapeworm in North America often reported as a serious ecological threat to native fishes. In this paper, we report the first record of B. acheilognathi in the Big Bend region of the Rio Grande in Texas (known as the Río Bravo del Norte in Mexico). Identification of B. acheilognathi was confirmed by morphologic and genetic techniques (sequences of ITS2 and V4-18S rRNA genes). Its prevalence was 27% and its intensity ranged from 1 to 5 individuals in a January 2006 collection of 115 red shiners Cyprinella lutrensis. In addition, it was found in the Tamaulipas shiner Notropis braytoni, a Rio Grande endemic and a new host record. The occurrence of B. acheilognathi might have negative ecological impacts on endemic fishes in the Rio Grande. Several of the fishes that could serve as definitive hosts are of conservation concern. Its occurrence also might affect the success of reintroducing the Rio Grande silvery minnow Hybognathus amarus, which is federally listed as endangered, in this portion of the Rio Grande.