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Length‐weight relationships (LWR) of eight fish species, Lepomis auritus (Linnaeus, 1758), Amphilophus labiatus (Gunther, 1864), Oreochromis mossambicus (Peters, 1852), Cichla ocellaris Bloch & Schneider, 1801, Parachromis managuensis (Gunther, 1867), Vieja melanura (Gunther, 1862), Pterygoplichthys pardalis (Castelnau, 1855), and Gobiomorus dormitor Lacepede, 1800, collected by electrofishing and gillnetting from ten reservoirs in Puerto Rico were determined using 3,557 individual fish records collected between 1998 and 2014. All LWRs were significant with r² values ranged from 0.900 for A. labiatus (Gunther, 1864) to 0.996 for C. ocellaris Bloch & Schneider, 1801. The LWR parameter b ranged from 2.807 for P. pardalis (Castelnau, 1855) to 3.180 for C. ocellaris Bloch & Schneider, 1801. Data presented herein expand the knowledge base for these species as they have limited or no LWR data available. Also, our samples provide a new maximum length data for P. pardalis (Castelnau, 1855).

A total of 71 stream sites representing a gradient of urban land use were sampled across the Piedmont of the south‐eastern United States in 2014. Fish data collected (observed) at each site were compared to an expected community based on georeferenced historical (~1950 ‐ ~1990) species occurrence records for stream segments (1:100,000 scale) containing the sampled stream sites. Loss of expected fish species (per cent of fish species expected to occur but not observed) and homogenization (difference in Jaccard's similarity of the fish community among sites observed and expected) were determined. On average, there was a 13.2% increase in the similarity of fish communities across sites, demonstrating evidence of community homogenization. Occurrence of Redbreast Sunfish (Lepomis auritus), Green Sunfish (L. cyanellus) and Bluegill (L. macrochirus) increased more than 50% over time (between observed and expected). Species loss increased significantly with urbanization, whereas homogenization was not related to urbanization. Random forest analysis indicated that herbicides, insecticides and centrarchid species richness were significant predictors of species loss. Of these, generalized additive model regression indicated that herbicides represented the most parsimonious model based on a single predictor. Stream base flow, elevation and total nitrogen were significant predictors of homogenization. Generalized additive model regression indicated that decreased stream base flow was the single most important factor associated with increased homogenization. Chemical contaminants and associated ecosystem alteration and changes in streamflow may represent important regional influences on changes in fish communities in urban streams in the south‐eastern United States.

The isotopic (δ13 C and δ15 N) and stoichiometric (C:N:P) compositions of four fish species (Family Centrarchidae: Lepomis auritus, Lepomis cyanellus; Family Cyprinidae: Nocomis leptocephalus, Semotilus atromaculatus) were examined across four North Carolina Piedmont streams arrayed along an urbanization gradient. Both isotopic and stoichiometric composition of fishes appeared to track changes occurring in basal resource availability. Values of δ13 C of basal resources and consumers were more enriched at the most urbanized streams. Similarly, basal resources and consumers were δ15 N-enriched at more urbanized streams. Basal resource stoichiometry varied across streams, with periphyton being the most variable. Primary consumers stoichiometry also differed across streams. Intraspecific variation in fish stoichiometry correlated with the degree of urbanization, as the two cyprinids had higher N content and L. cyanellus had higher P content in more urbanized streams, probably due to enrichment of basal resources. Intrinsic factors, specifically species identity and body size also affected stoichiometric variation. Phosphorus (P) content increased significantly with body size in centrarchids, but not in cyprinids. These results suggest that although species identity and body size are important predictors of elemental stoichiometry, the complex nature of altered urban streams may yield imbalances in the elemental composition of consumers via their food resources.

One pervasive outcome in the urbanization of an ecosystem is the proliferation and numerical dominance of select tolerant organisms that are often native to the system yet with reduced relative abundances in less-disturbed conditions. As a result of high variation in environmental conditions between urbanized and non-urbanized systems, it is possible that the functional role of a ubiquitous organism is context dependent. Such is the case for redbreast sunfish (Lepomis auritus) in small streams in many parts of the Piedmont of the southeastern USA. To investigate this hypothesis, we evaluated the feeding, growth, and trophic position of redbreast sunfish in 3 streams of increasing levels of watershed urbanization (forested, suburban, urban) in the Lower Piedmont of western Georgia, USA. Through gut contents analysis, we found that sunfish consumed primarily Chironomidae (Diptera) larvae across all streams. However, fish in the suburban stream consumed more terrestrial prey than fish in the forest and urban streams, which corresponded to lower aquatic prey abundances in the suburban stream. Although there was no difference in mean fish age among streams, otolith analysis revealed that fish in the urban stream were larger at age than those in the forest stream. Last, stable isotope analysis revealed that fish in the urban stream occupied a lower trophic position than the other 2 streams. These results suggest that despite the fact that the primary prey resource was similar for sunfish in each stream, their potential functional role, as evidenced by size at age and trophic position, is context dependent.

The gross morphology and electrical activity of the muscles of the pharyngeal apparatus of centrarchid sunfishes (Lepomis) are analyzed within a monophyletic clade containing species specialized for snail-eating. Outgroup comparisons of both structure and activity patterns of muscles permit examination of the relationship between specialized diet and function of the trophic apparatus. In most sunfish species, electrical activity in the pharyngocleithralis internus muscle significantly overlaps that in the retractor dorsalis muscle during pharyngeal transport, indicating that the upper and lower pharyngeal jaws retract together. Activity in the pharyngohyoideus, levatores externi, and levator posterior also significantly overlaps activity of the retractor dorsalis. Snail-eating is associated with derived morphological, behavioral, and functional features. The shell is crushed before pharyngeal transport, correlated with extensive overlap in activity periods of muscles. One species, Lepomis microlophus, possesses a highly stereotyped neuromuscular repertoire that does not vary with prey type. All prey, even fish and worms, are subjected to crushing. Lepomis gibbosus exhibits the crushing pattern of muscle activity only when feeding on snails. L. microlophus has a hypertrophied levator posterior muscle, but the lines of action of the pharyngeal muscles are similar to the primitive condition. Pharyngeal transport in this species is unique in that activity of the pharyngocleithralis internus alternates with that of the retractor dorsalis. In sunfishes, alterations in the central control of peripheral structures have produced major changes in the sequence in which homologous components of the structural network are activated.

The availability of water is becoming more variable as flow regime alterations intensify both locally and on a global scale. This pattern has been observed in the tributaries of the central Chattahoochee River System as water withdrawal and natural drought have caused flows to diminish. Stream discharge has steadily decreased in the study area by 31% over the last 50 years, and during this time, fish assemblage homogenization has occurred throughout the system. Our primary objective was to assess whether spawning mode and water availability are catalysts for fish assemblage change in tributaries of the Chattahoochee River System. We found that species which prefer or have adapted to low flow conditions (e.g. blacktail shiner Cyprinella venusta, redbreast sunfish Lepomis auritus and blackbanded darter Percina nigrofasciata) are becoming dominant and replacing historically dominant fluvial specialists. When examining short-term changes between a dry year (2009) and a wet year (2010), some species preferring higher flows such as the highscale shiner Notropis hypsilepis were detected during the wet year, suggesting that the amount of water is important for the presence of these species in upstream reaches where they were historically abundant. Species that can reproduce successfully in low flow conditions are thriving and expanding their native ranges as more habitat becomes suitable. Species that require higher flows for part of their life cycle, however, appear to be declining from upstream areas as water availability continues to decrease, despite temporary recovery from downstream refugia during wet years.

The freshwater fish parasite Leptorhynchoides thecatus contains several cryptic species that vary morphologically, molecularly, and in host use. This study investigated 404 individual fish for the presence of Leptorhynchoides, representing 24 species of fish from Otsego Lake, a glacially formed lake in New York, U.S.A. Of the 24 fish species represented, 12 species were infected with adult Leptorhynchoides in the digestive tract, including 4 species that were infected with gravid female worms: largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu), rock bass (Ambloplites rupestris), and redbreast sunfish (Lepomis auritus). Individuals from 5 fish species were infected with both adult worms in the digestive tract and with cystacanths in the body cavity. Measurements taken from specimens of the trunks, proboscides, and hooks, along with genetic sequences obtained from specimens at the mitochondrial gene cytochrome oxidase I (Cox1), suggest that the specimens encountered he...

The city of Greenville, SC is a rapidly expanding urban area located on the Reedy River in the upstate of South Carolina. Historical and current point-source pollutants and runoff from impermeable surfaces have resulted in a contaminated river environment, which through previous studies was demonstrated to be reflected in biological effects in fish species in the river. Because it was not known how much smaller tributaries in the urbanized area were contributing to the pollution of the main stem of the Reedy River, we collected fish (bluehead chub (Nocomis leptocephalus), creek chub (Semotilus atromaculatus), bluegill (Lepomis macrochirus), and redbreast sunfish (Lepomis auritus)) from five smaller urban creeks in the Greenville area and measured several biomarkers of exposure in these animals. Enzymatic activities of cytochrome P450-1A (CYP1A) and glutathione S-transferase (GST) were measured, and bile samples were analyzed for fluorescence caused by polynuclear aromatic hydrocarbons (PAHs) and for excreted estrogenic compounds. The results show that some creeks triggered significant biomarker responses in collected fish, while others were relatively clean. In particular, PAHs appear to be prevalent and caused biochemical effects, while estrogenic compounds were not significantly increased in the bile of fish from these urban creeks. A striking observation was the difference in enzyme activities in chub species compared to sunfish species; sunfish had up to five times higher CYP1A activities than chubs, while the chubs had significantly higher GST activity than sunfish. These species differences should be taken into account when they are incorporated in environmental risk assessment and biological effect monitoring programs.

A two-year electrofishing study was initiated in the Tallapoosa River, Alabama, to identify an optimal standardized sampling program for three principal resident sportfish: Alabama bass Micropterus henshalli, redbreast sunfish Lepomis auritus, and redeye bass Micropterus coosae. Samples were conducted in spring (May), summer (July), and fall (October) in 2010 and 2011 from seven 1-h transects. Spring samples of Alabama bass had lower catch per effort (CPE) and were more skewed towards fish between 200 and 300 mm total length (TL) than samples in other seasons; whereas, fall samples collected more redeye bass >200 mm TL but CPE was similar among seasons. Fewer, but larger, redbreast sunfish were sampled during fall compared with other seasons. Mean CPE of all three species was independent of transect duration. The total time spent electrofishing and processing fish in order to estimate a mean CPE with a specified precision was a function of transect duration and CPE. More effort was needed as CPE decreased for most species, but the relations between transect duration and total effort were parabolic. A precision of within 10% of the mean CPE was unattainable for most species as a result of logistic considerations. Based on the results of this study, it appears that fall is the optimal sampling time for these species in the Tallapoosa River and the optimal transect duration is likely 10 min. At a precision level of 20% of the mean, the number of 10-min transects required ranged from 5 to 40, with a total sample time for each individual species of 0.82–7.16 h. Copyright © 2014 John Wiley & Sons, Ltd.

Thermal tolerances have been studied for individual fish species but few have investigated how stream fish assemblages respond along a temperature gradient and which thermal ranges act as a threshold, triggering discernible community change. The purpose of this study was to define summer temperature thresholds of fish community transitions in Connecticut streams. The program Threshold Indicator Taxa Analysis suggested that the coldwater class had a June–August mean water temperature 21.70°C. Significant indicator species of coldwater streams were Slimy Sculpin Cottus cognatus and Brook Trout Salvelinus fontinalis. Significant indicator species of warmwater streams were Cutlip Minnow Exoglossum maxillingua, Smallmouth Bass Micropterus dolomieu, Rock Bass Ambloplites rupestris, Brown Bullhead Ameiurus nebulosus, Redbreast Sunfish Lepomis auritus and Yellow Bullhead A. natalis. The narrow 3.41°C temperature range between the coldwa...

Predation is a dominant and influential factor in most ecological communities. However, little is known about how the federally endangered Barton Springs Salamander, Eurycea sosorum, responds to predators. Using captive-hatched (predator-nasalamanders, we examined the antipredator response of E. sosorum to chemical cues from (1) native Western Mosquitofish (Gambusia affinis), (2) introduced Redbreast Sunfish (Lepomis auritus), (3) native Largemouth Bass (Micropterus salmoides), and (4) a blank water control. Salamanders decreased activity (antipredator behavior) in response to all fish treatments but not to the blank water control. There was no difference between the response to the G. affinis and L. auritus, but salamanders responded less to these treatments than to M. salmoides. The antipredator response to G. affinis may be an ontogenetic hold over as G. affinis has been found to consume amphibian larvae and eggs. In an additional study to test whether antipredator behavior was a generalized response to all fish species, we found that E. sosorum did not respond to small, nonnative, nonpredatory Guppies (Poecilia reticulata). This suggests that the observed behavior in our first experiment represents antipredator behavior specific to the species tested. Overall, these results indicate that E. sosorum has innate recognition of predatory fish, and that the stronger antipredator response to M. salmoides over the other fish species may be an outcome of risk assessment. The antipredator response to G. affinis has management implications as G. affinis is sympatric with the largest population of E. sosorum, and may be consuming both eggs and larvae of these salamanders.

This survey of parasites in 2 adjacent lakes is the first of its kind in the Adirondack Park of New York State. Wolf Lake is designated as a heritage lake whereas nearby Deer Lake is limnologically similar but has at least 5 introduced fish species. Both lakes have 2 native species, i.e., white sucker (Catostomus commersoni) and redbreast sunfish (Lepomis auritus), which were the focus of this study. Parasite communities of both hosts were surveyed and compared between each lake and were statistically evaluated for differences in species similarity, prevalence, mean intensity, and mean abundance. Between lakes, white suckers had significant differences in the prevalence of 4 parasite species (Myxobolus sp. 2, Myxobolus bibulatus, Octospinifer macilentis, and Pomphorhynchus bulbocoli) and mean abundances of 4 parasites (neascus larvae, Octospinifer macilentis, Pomphorhynchus bulbocoli, and Glaridacris confusus). Redbreast sunfish had significant differences in the prevalence of 3 species (Myxobolus uvuliferis, a coccidian species, and Spinitectus carolini) and differences in parasite mean abundance of 5 species (neascus larvae, Clinostomum marginatum , Leptorhynchoides thecatus, Spinitectus carolini, and Eustrongylides sp.). Differences in component communities between lakes were found and, although the exact causes cannot be determined by this study, we speculate on several possible explanations.

Observations in a previous study on biomarker responses in fish collected from urban creeks in Greenville, SC, indicated that there might be considerable differences in the expression of biotransformation enzymes in chub and sunfish species. To further investigate these species differences a dosing experiment was performed in which bluehead and creek chub (Nocomis leptocephalus and Semotilus atromaculatus), and redbreast sunfish, pumpkinseed, and bluegill (Lepomis auritus, L. gibbosus, and L. macrochirus) were injected with benzo[a]pyrene (BaP) as a model compound for common pollutants in urban creeks. Fish were injected with BaP doses of 0, 25 and 50mg/kg, and after 3days BaP metabolites in bile, and enzymatic activities of cytochrome P450-1A (CYP1A), UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST) were measured. CYP1A activity was significantly increased after BaP dosing in both species groups, but chubs had significantly lower levels than were observed in the dosed sunfish. The UGT activity in unexposed animals was comparable in both species groups, and significantly increased in both groups as a result of BaP dosage. Finally, GST activity was significantly higher in chubs, but did not change in either species group as a result of BaP exposure. There were no significant differences between species within each species group, and the results confirmed that unexposed chubs have much lower CYP1A activity, but a much higher GST activity than unexposed sunfish. The metabolized BaP was excreted in both species groups, but at the time of sampling there were no differences in the amount of BaP metabolites in the bile of dosed animals. The differences in baseline enzyme activity and induction capacity between both species groups are an example of phylogenetically determined differences between fish families, and may explain why chubs are in general more sensitive to exposure to environmental pollutants than sunfish. This conclusion was corroborated by the observation that the highest BaP dose of 50mg/kg was close to the apparent LC50 for chub, while no mortality was observed in the sunfish at this dose.

Deviations in bilateral symmetry or fluctuating asymmetry of an organism may result under environmental stressors that reduce developmental homeostasis and stability. Anthropogenic stressors such as increased urbanization can negatively impact environmental quality of aquatic ecosystems. Researchers have stressed the value in finding easy, accurate and inexpensive methods for assessing potential stress within ecosystems. Here we use fluctuating asymmetry (FA) as a useful quantitative tool in assessing the environmental quality and potential urban-based stressors within eight creeks of the Bull and Upatoi Creeks Watershed within the larger watershed of the Middle Chattahoochee. Using Geographic Information System (GIS), we characterize land-use patterns and a decreasing urbanization gradient as related to each creek’s eastward position from Columbus, Georgia. We collected two common fishes (redbreast sunfish; Lepomis auritus and bluegill; Lepomis macrochirus), measured both metric and meristic traits and investigated if the degree of FA in these two common fishes correlated with the urbanization gradient across creeks. We found significant differences in FA among creeks with one of the highest FA measures for the most urban creek. Principal component analysis (PCA) scores of urbanization and water chemistry were regressed against FA scores. We found no significant relationship between urbanization and FA nor environmental water chemistry and FA among creeks. We comment on the use of FA as a potential response variable and biological indicator of environmental stress within this watershed.

In Canada, Lepomis auritus (Redbreast Sunfish) is only found in southwestern New Brunswick, which is the northern limit for the species. In 1989, The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) listed it as a species of special concern due to its limited distribution, and changed the status to data deficient in 2008. The purpose of our study is to begin to build a database of ecological information for the Redbreast Sunfish in New Brunswick. The most northern population occurs in Yoho Lake. Population estimates averaged 386 from 2005 to 2007. The average total length and weight were 12.5 ± 3.1 cm and 42.6 ± 27.3 g, respectively. The length-frequency distributions were consistent over the years, suggesting a stable population structure. Most adult and juvenile sunfish were observed in areas of dense vegetation and large woody debris. Snorkeling surveys were conducted from late June to early July 2005–2007 to assess timing and habitat preference of spawning Redbreast Sunfish. The nests averaged 52.4 ± 10.1 cm in diameter and were 43.9 ± 12.2 cm deep. Nest substrate was sandy with small gravel, and only 33% of the nests were associated with a physical structure in the water column. Overall, the population of Redbreast Sunfish in Yoho Lake appears to be healthy and stable.

The introduction of novel predators into an environment can have detri- mental consequences on prey species, especially if these species lack the ability to recognize these predators. One such species that may be nega- tively affected by introduced predators is the federally threatened San Mar- cos salamander (Eurycea nana). Previous research found that predator-naive (captive-hatched) salamanders showed decreased activity in response to the chemical cues of both a native fish predator (Micropterus salmoides )a nd an introduced fish predator (Lepomis auritus), but not to a non-predatory fish (Gambusia geiseri). We tested the hypothesis that E. nana recognized the introduced Lepomis (and other non-native Lepomis) because they share chemical cues with other native congeneric Lepomis predators in the San Marcos River. We examined the antipredator response of predator-naive E. nana to chemical cues from (1) a sympatric native sunfish (Lepomis cyanellus; Perciformes: Centrarchidae); (2) a sympatric introduced sunfish (L. auritus); (3) an allopatric sunfish (Lepomis gibbosus); (4) a sympatric non-native, non-centrarchid cichlid (Herichthys cyanoguttatum; Perciformes: Cichlidae); and (5) a blank water control to determine whether individuals make generalizations about novel predators within a genus and across a family. Exposure to chemical cues from all fish predator treatments caused a reduction in salamander activity (antipredator response). Additionally, there were no differences in the antipredator responses to each predatory fish treatment. The similar responses to all sunfish treatments indicate that E. nana shows predator generalization in response to novel predators that are similar to recognized predators. Additionally, the antipredator response to H. cyanoguttatum indicates that predator generalization can occur among perciform families.

Concerns over the recent introduction of Micropterus punctulatus (Spotted Bass) on native M. salmoides (Largemouth Bass) and M. cataractae (Shoal Bass) prompted a one-year investigation into the food habits of these three congeneric species to determine diet overlap and potential for trophic competition in the Flint River, GA. Diet analyses among species were conducted for two size classes offish: juvenile ( 300 mm were collected; thus, diet overlap was not compared among species for larger fish. Juvenile and subadult Largemouth Bass diets were dominated by fish in all seasons, mainly sunfishes (e.g., Lepomis auritus, L. macrochirus). In contrast, Shoal Bass diets were generally dominated by insects and crayfish in the juvenile and subadult size classes, respectively. Juvenile Spotted Bass diets were variable and dominated by fish and in...

We designed a digital underwater video camera system to monitor nesting centrarchid behavior in the Tallapoosa River, Alabama, 20 km below a peaking hydropower dam with a highly variable flow regime. Major components of the system included a digital video recorder, multiple underwater cameras, and specially fabricated substrate stakes. The innovative design of the substrate stakes allowed us to effectively observe nesting redbreast sunfish Lepomis auritus in a highly regulated river. Substrate stakes, which were constructed for the specific substratum complex (i.e., sand, gravel, and cobble) identified at our study site, were able to withstand a discharge level of approximately 300 m3/s and allowed us to simultaneously record 10 active nests before and during water releases from the dam. We believe our technique will be valuable for other researchers that work in regulated rivers to quantify behavior of aquatic fauna in response to a discharge disturbance.

Summary 1. Hyper-successful exotic species can both displace the native prey that formerly made up a native predator’s diet and represent an abundant potential prey resource for native predators. Little is known about how this drastic change affects native predators, or their short- and long term potential to regulate the exotic species. 2. We compared zebra mussel consumption by pumpkinseed sunfish (Lepomis gibbosus), redbreast sunfish (Lepomis auritus) and rock bass (Ambloplites rupestris) from populations that were either previously exposed to zebra mussels or naive to them. 3. Fish from populations with longer exposure to zebra mussels consumed many more zebra mussels than fish from populations with shorter or no previous exposure to zebra mussels. 4. Our experiment does not allow us to identify the mechanisms that underlie the patterns we found, but we discuss several plausible scenarios and their ecological implications. 5. Predator adaptation to exotic prey may be an important but overlooked factor in invasion biology. The initial response to exotic prey by a native predator may be a poor estimate of its ability to present biotic resistance to the invasion over the long term.

The following 3 new species of the Philometridae (Nematoda: Dracunculoidea) are described from freshwater centrarchid fishes (Centrarchidae: Perciformes) from eastern North America on the basis of museum and newly collected specimens: Philometra orbitalensis n. sp. and Philometroides aphanonaris n. sp. from the oculo-orbits and subcutaneous tissues of the head, respectively, of the largemouth bass Micropterus salmoides, and Philometroides wellborni n. sp. from the oculo-orbits of the bluegill Lepomis macrochirus (type host) and the redbreast sunfish Lepomis auritus. Whereas P. wellborni is described from both males and gravid females, the males of P. aphanonaris and P. orbitalensis remain unknown. The type locality of all 3 species is the West Point Reservoir, Alabama-Georgia; P. aphanonaris and P. wellborni have also been recorded from the Santee River in South Carolina. In contrast to other Philometra spp. parasitizing North American freshwater fishes, the gravid females of P. orbitalensis are characterized by large cephalic papillae of the external circle, yellowish body color, location (oculo-orbits) in the host, and by the host type (Centrarchidae). Philometroides aphanonaris and P. wellborni differ from North American congeners from freshwater fishes in the absence of esophageal teeth or a different embossment of the caudal end in gravid females; P. wellborni differs from P. aphanonaris in the absence of cuticular bosses from the caudal end of gravid females and in some other features (extent of embossment, body color, location, and host type).

The effects of minimum length limits (MLLs) on bluegill, Lepomis macrochirus Rafinesque, redbreast sunfish, Lepomis auritus (Linnaeus), and redear sunfish, L. microlophus (Gunther), fisheries in 13 river sections located across Georgia were evaluated. A Beverton–Holt equilibrium yield model was used to predict and compare the response of these fisheries to three MLL scenarios: 100 (i.e. no size limit), 125 and 150 mm. Model results indicated that natural mortality rates of all sunfish species examined in this study were low enough to allow harvest restrictions to be effective if growth was fast. If sunfish reached 203 mm in

To determine effects of pulp mill effluent on population genetic structure, redbreast sunfish (Lepomis auritus) were collected from several sites along the Pigeon River, NC, as well as from reference sites. Previous studies found effects on molecular, biochemical, physiological, population, and community level endpoints in these populations. The population genetic structure of these fish was determined using the randomly amplified polymorphic DNA (RAPD) technique. The level of genetic diversity was higher in the Pigeon River populations than in the reference populations. Genetic distances among populations could not be explained by drainage patterns and may have been altered by contaminant exposure. Phylogeographic analysis, maximum likelihood analysis, and assignment tests suggested that there were fewer emigrants and more immigrants in the contaminated sites than in the reference sites, suggesting that the contaminated sites may harbor "sinklike" populations. Finally, a "terminal branch amplitype" analysis (neighbor-joining and minimum-spanning trees) and maximum likelihood analysis indicated that there may be an elevated mutation rate in the polluted sites. Thus, the genetic diversity (within and among populations) in the Pigeon River populations may have been affected by altered gene flow and mutational processes as a result of pulp mill effluent discharge.

Radiocesium ({sup 137}Cs) concentrations were determined during 1974, 1981 and 1998 for seven species of fish inhabiting a stream (Steel Creek) contaminated by effluents from a nuclear reactor to examine the decline of this radionuclide in a natural ecosystem. Median {sup 137}Cs concentrations were highest in Micropterus salmoides (largemouth bass) during each year of the investigation (1974 = 6.67 Bq g{sup -1} dry wt. of whole body; 1981 = 3.72 Bq g{sup -1}; 1998 = 0.35 Bq g{sup -1}), but no patterns of differences were observed among Aphredoderus sayanus (pirate perch), Esox americanus (redfin pickerel), Lepomis auritus (redbreast sunfish), L. gulosus (warmouth), L. punctatus (spotted sunfish), and Notropis cummingsae (dusky shiner). Results demonstrated a rapid decline in {sup 137}Cs within fish from Steel Creek during the 24-year period. For example, {sup 137}Cs concentrations in all fish species declined significantly among years, even after accounting for radioactive decay. The observed percent declines in {sup 137}Cs concentrations of individual species were 3-4 times greater between 1974 and 1981 compared to that expected by physical decay alone, and 2-3 times greater during 1981-1998. Ecological half-lives (EHLs) of {sup 137}Cs in fish ranged from 4.43 years in A. sayanus to 6.53 years in L.more » gulosus. The EHL for {sup 137}Cs in all fish species combined was 5.54 years. Current levels of {sup 137}Cs in fish from Steel Creek (1.16 Bq g{sup -1} dry wt. of whole body to below detection limits) indicate that the consumption of fish from this ecosystem poses little risk to humans and sensitive wildlife species. These results demonstrate the importance of incorporating the concept of ecological half-life into determinations concerning the length and severity of potential risks associated with radiocontaminants.« less

Despite a great diversity of reproductive behaviors in fishes, few studies have examined the genetic consequences of alternative reproductive tactics. Here we develop and employ microsatellite markers to assess genetic paternity and maternity of progeny cohorts in a population of redbreast sunfish (Lepomis auritus), a species in which males build and tend nests. Nearly 1000 progeny from 25 nests, plus nest-attendant males and nearby adults, were genotyped at microsatellite loci that displayed more than 18 alleles each. The genetic data demonstrate that multiple females (at least two to six) spawned in each nest, their offspring were spatially dispersed across a nest, and more than 90% of the young were sired by the attendant male. However, about 40% of the nests also showed genetic evidence of low-level reproductive parasitism, and two nests were tended by males that had fathered none of the sampled offspring. Genetically deduced reproductive behaviors in this population of redbreast sunfish contrast with those reported previously in bluegill sunfish (L. macrochirus) wherein heteromorphic males specialized for parasitism or for parental care coexist in high frequency. Thus, nest-parasitic reproductive behaviors in fishes appear to be evolutionary labile.

Bioindicators of pollutant exposure can be more sensitive and ecologically relevant than simply measuring levels of pollutants in the environment and are applied here as a tool for assessing environmental stress on aquatic organisms. DNA polymorphisms, detected by using the randomly amplified polymorphic DNA (RAPD) technique, are used as biomarkers to assess genetic diversity and genetic distance among populations of redbreast sunfish (Lepomis auritus) residing in reference streams and a contaminated stream (East Fork Poplar Creek, EFPC). The RAPD technique uses the polymerase chain reaction (PCR) with short oligonucleotide primers under reduced stringency to produce DNA fragments which, when analyzed by gel electrophoresis, form banding patterns similar to DNA fingerprints. A total of 13 primers were used which produced 45 polymorphic bands among all populations of fish tested. Using this technique, only slight differences in genetic diversity were detected among populations of sunfish within EFPC although the diversity of all EFPC populations analyzed together did differ from the reference populations. Fish populations in EFPC were consistently less genetically distant from each other than they were from each of the reference sites. Differences in genetic distance between populations may be due to selection pressure of pollutants on fish in EFPC which is supported by the finding that frequencies of certain unique genotypes in EFPC sunfish were correlated with the downstream pollutant gradient. These results are discussed in relation to implications of RAPD assays and recent remediation efforts within EFPC.

Bioindicators of fish health were measured from 1989 through 1994 in populations of redbreast sunfish (Lepomis auritus) at three sites within a stream receiving inputs of mixed contaminants from an industrial facility, and at two reference sites. Bioindicator responses differed for fish from contaminated and reference sites throughout the study period, but temporal trends at contaminated sites reflected improved water quality associated with pollution-control efforts. Temporal variability unrelated to contaminant exposure strongly influenced the response of bioindicators at both reference and contaminated sites, but spatial variability rarely influenced these responses. Temporal variability was less influential on slower responding indicators at higher levels of biological organization. The diverse response characteristics of indicators increased the ability to differentiate natural from anthropogenic sources of variability. Integrated bioindicator responses were compared among site-year groups by multivariate canonical analysis. The primary canonical variable, associated with differences in growth, exhibited trends consistent with the timing of pollution-control efforts. Two indicators of contaminant exposure (7-ethoxyresorufin O-deethylase activity and polychlorinated biphenyls in fish muscle) also exhibited trends consistent with the timing of pollution-control efforts, but the likelihood of possible mechanistic linkages cannot be assessed with available data.

Histopathologic alterations of gill, liver, and spleen were studied in feral fish from three freshwater ecosystems that experience different types of contaminant stress. East Fork Poplar Creek (EFPC), a third-order stream in East Tennessee, receives point source discharges of mixed contaminants from a nuclear weapons facility located near its headwater. The Pigeon River (PR), a high-gradient fifth order stream, is impacted by bleached kraft mill effluent (BKME). Hartwell Reservoir (HR), a US Army Corp of Engineers impoundment of the Savannah River, contains high levels of PCBs in sediment and biota. Brushy Fork Creek (BFC), the Little River (LR), and the Tugaloo River (TR) are relatively free of contaminants, and served as reference sites for the three respective ecosystems of this study. Certain organ and tissue lesions, detected microscopically, were common to fish from both reference and contaminated sites. These included parasites, inflammation, glycogen deficiency, macrophage aggregates (MA), and diffuse fatty change in the liver; parasites and MA in the spleen; and parasites, secondary lamellar fusion, and variable epithelial cell hyperplasia in the gills. Lesions found only in fish from contaminated sites were: (1) cholangiomas in liver of redbreast sunfish (Lepomis auratus) collected from EFPC; (2) amphophilic and eosinophilic foci of cellular alteration, diffuse biliary preductular and ductular hyperplasia with islands of hyperplastic basophilic hepatocytes, and two metastatic thyroidal carcinomas in spleen of redbreast sunfish from PR; (3) severe lipidosis, vacuolated and basophilic foci in largemouth bass (Micropterus salmoides) from HR; (4) splenic lymphoid cell depletion and vascular congestion, with necrosis of reticuloendothelial cells in fish collected from EFPC and HR; (5) hyperplasia of mucous and chloride cells, deformed branchial cartilage, severe and diffuse aneurysms of lamellae, and edema at the base of the secondary lamellae were in gill of fish from all three sites. The finding of specific lesions only in fish from contaminated sites suggests a contaminant etiology. Histopathology biomarker lesions identified in this study are similar to those observed in laboratory exposures of fishes to specific pollutants. Further refinement of these biomarker approaches will be discussed in light of multiple stressors and their effects.

1. Inputs of terrestrial arthropods (number and mass m–2 d–1) from riparian corridors to three streams representing different orders were highly variable among seasons and sites, with significantly greater (P < 0.05) inputs at the headwater stream during summer months, compared with other sites and seasons. 2. No significant differences in estimates of stream retention of terrestrial arthropods (number and mass m–2 d–1) were observed among sites; however, retention of terrestrial arthropods at all sites was significantly greater during summer months, compared with other periods. 3. The gravimetric proportion of terrestrial arthropods present in the stomachs of redbreast sunfish (Lepomis auritus) and bluegill (L. macrochirus) was equivalent among sites. However, estimates of the dietary importance of terrestrial arthropods at all study sites were significantly greater in the summer, compared with other seasons. 4. Estimates of the potential annual energetic contribution (kJ m–2 d–1) of terrestrial arthropod inputs to the stream system were comparable with published rates of total annual production of aquatic macroinvertebrates in other Virginia headwater streams. 5. Results of this study supported the hypothesis that terrestrial arthropods represented an important energetic subsidy to stream fish during periods of low aquatic macroinvertebrate availability, and suggest that this component of allochthonous input is a potentially significant, but poorly understood energetic linkage between riparian landscapes and stream ecosystems.

The ecological risk assessment of East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee, investigated the nature and magnitude of the observed or expected adverse effects of the site's organic and inorganic contaminants on the ecosystem structure and function. Aquatic biota such as benthic macroinvertebrates, crayfish (Astacidae), redbreast sunfish (Lepomis auritus), and stonerollers (Campostoma anomalum), representative of various habitats, were sampled for whole-body contaminant analysis. The whole-body residue analysis of the representative aquatic organisms revealed the presence of over 50 contaminants in varying proportions. The relative whole-body distribution of organic contaminants such as mixtures of polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and pesticides was comparable among the indicator organisms. The relative whole-body distribution of inorganic contaminants was, however, less consistent. Physicochemical variables characteristic of organic contaminants—such as long octanol/water partition coefficient (logKow), log aqueous solubility, and log bioconcentration factors (log BCF), and chemical uptake efficiency (E) unique for the organisms sampled for chemical analysis—were used to explain the observed whole-body distribution of contaminants in the aquatic organisms from EFPC.

We examined diel feeding chronology of six fish species in the Juniata River, Pennsylvania. Ephemeropteran nymphs were the major prey of redbreast sunfish (Lepomis auritus; 70.5%) and smallmouth bass (Micropterus dolomieu; 59.7%) during each of six 4-h intervals over a 24-h period. The main dietary component of mimic shiner (Notropis volucellus) was chironomids (42.3%), whereas spotfin shiner (Cyprinella spiloptera) mainly ate terrestrial invertebrates (50.2%). Juvenile white sucker (Catostomus commersoni) exhibited substantial diel variation in diet composition with some prey taxa composing the entire diet during some 4-h intervals and being completely absent from the diet during other periods. Bluntnose minnow (Pimephales notatus) contained mostly detritus (75.5%). Interspecific diel diet overlap (Cγ) was low among the six species except for smallmouth bass-redbreast sunfish (0.735). Mimic shiner ([xbar] = 0.302) had the highest diet overlap with other species and bluntnose minnow ([xbar] = 0.1...

The form of mercury predominating in mercury-contaminated fish from both pristine and industrialized waters in North America and Europe has almost universally been methylmercury. Sunfish (Lepomis auritus) living in a stream contaminated with 0.5-1 micrograms/L dissolved inorganic mercury accumulated greater concentrations of total mercury at headwater sites, where the dissolved mercury concentrations were greatest, than they did at downstream sites. However, despite evidence from laboratory studies that dissolved inorganic mercury is rapidly accumulated by fish without transformation to methylmercury, methylmercury constituted 85% or more of the total mercury concentration in fish at all sites.

We studied the movements of redbreast sunfish (Lepomis auritus), bluegill (Lepomis macrochirus), rock bass (Ambloplites rupestris), largemouth brass (Micropterus salmoides), and warmouth (Lepomis gulosus) by tagging fishes with individually numbered tags. We sampled quarterly over a 3-year period (1985–1988) at six 800- to 2300-m-long sites in 2 streams near Oak Ridge, Tennessee. Overall, distances between successive captures were 10 km. In general, all species were highly sedentary in both streams, with rock bass and redbreast sunfish being the most sedentary and bluegill and largemouth bass being the least. In most instances, redbreast sunfish showed the same distribution of distances between captures regardless of the interval between captures (1 week, 3 months, 6 months or more). This species also tended to be more mobile in the spring and less mobile in the winter, with large fish exibiting the greatest distances between captures. Some redbreast sunfish showed a very restricted home range, being captured 3 or more times over ≥ 6 months in the same 50-m section of stream. A few individuals moved 4-9 km only to return to their original location, but most fish exhibited behaviors intermediate between these extremes. For all species, upstream and downstream movements were equally common, although movements in one direction predominated at some sites for limited periods of time. Knowledge of movement patterns and differences in behavior among species is important not only in understanding the basic ecology of the species but also in designing, conducting and interpreting environmental monitoring studies.

In North Anna River, Virginia, redbreast sunfish Lepomis auritus began spawning in late May, 1992, when water temperatures exceeded 20°C. Spawning occurred in pool habitat with low velocities (

In a field study, DNA damage, hematological parameters, and liver somatic index were measured in fish collected from freshwater creeks contaminated with polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs) (East Tennessee) and from estuarine and marine waters contaminated with PAHs and cadmium (Mississippi Sound). For comparison, specimens were examined from two pristine reference sites near the impacted Tennessee and Mississippi sites. Significantly more strand-breaks were found in DNA isolated from liver tissue of redbreast sunfish (Lepomis auritus) from contaminated creeks than in DNA from sunfish from two pristine creeks. Hemoglobin concentration (CHb) and mean corpuscular hemoglobin concentration (MCHC) were significantly higher in both male and female sunfish from the pristine creeks. Furthermore, the liver somatic index (LSI) of sunfish from contaminated creeks was higher than that of specimens from reference sites. In adult male, female, and juvenile hardhead catfish (Arius felis) from suspected contaminated sites in the Mississippi Sound, high LSI and lowered CHb and MCHC were found. A higher percentage of double-stranded DNA was measured in specimens from the pristine reference sites. Individual differences in responses of the biological markers, however, were large, as reflected by high standard deviations. The biological responses measured were obviously valuable to indicate differences in the environmental quality expressed in molecular and physiological terms.

Effects of river discharge on growth of redbreast sunfish Lepomis auritus were investigated in nine rivers in Georgia, U.S.A. Fish were aged and annular total length increments (L(Tinc)) estimated from measurements from sectioned sagittal otoliths using the generalized regression model that held for the effects of decreasing L(Tinc) from annual age (X): L(Tinc)=b(o)-b(1)(X) +/-b(i)(D), where b(o), b(1) and b(i) were the regression coefficients for the intercept and slopes and D, discharge, was either a single or multiple measurements of annular or seasonal flow volume or variation in flow volume. For eight of nine rivers, higher or greater variation in flows from April to June was associated with greater L. auritus growth; in the last river, higher flows from January to March were associated with greater fish growth. Across all rivers, L. auritus growth increments were 22, 45 and 36% greater in a wet year v. a dry year at ages 1, 2 and 3 years, respectively. Based on the results of this study, increasing water withdrawals by an additional 30% in five Georgia rivers would reduce the predicted number of L. auritus recruiting to 203 mm (angler preferred size) by 19-62%.

Relationships between toxicant exposure, physiological effects, and population-level responses were investigated in redbreast sunfish (Lepomis auritus) from a stream receiving chronic inputs of mixed contaminants. Elevated levels of detoxification enzymes, which provided evidence of direct toxicant exposure, were associated with low lipid levels, histopathological damage, and reduced growth for fish at the upper three sites in the contaminated stream. Decreased fecundity, exhibited by fish at the upper site, might have been due to the reduced capacity of the liver to manufacture yolk proteins. Reduction in lipid pools due to metabolic drains might have decreased the amount of physiological useful energy needed for growth resulting in smaller age-specific sizes of fish at the upper three sites. This approach for investigating relationships between contaminant exposure, physiological effects, and population-level responses such as growth and size distributions could serve as a model for designing biomonitoring studies and for stimulating further research to improve our ability to evaluate the ecological significance of chronic contaminant stressors on aquatic ecosystems.

Sunfish (Lepomis auritus and L. macrochirus) were used to monitor polychlorinated biphenyl (PCB) contamination in a group of small streams flowing into a larger stream/reservoir system. Mean PCB concentrations in sunfish appeared to reflect exposure conditions at the site of capture. Fish from uncontaminated sites 1 to 2 km distant from PCB-contaminated sites did not exhibit PCB contamination, and PCB concentrations in fish downstream from a discrete source decreased at a rate greater than or equal to downstream dilution of the point source. Mean PCB concentrations in fish near the source exhibited relatively large (-40%) fluctuations between semi-annual sampling periods, suggesting that PCB concentrations in sunfish populations may respond rapidly to changes in exposure. Sunfish were not sensitive enough indicators of contamination to use in assessing whether or not problematic levels of contamination may occur in other species. Although the presence of PCB contamination in sunfish can be used to infer that PCBs are elevated in other species, the absence of PCB contamination in sunfish cannot be used to infer that older, fattier fish higher up the food chain are uncontaminated.

Both federal and state governments have regulations requiring road crossings to facilitate Aquatic Organism Passage (AOP). Due to a current inability to prove that AOP will not be inhibited, acquiring permits for the design and construction of culverts has become difficult. Often, bridges costing up to three times as much must be built in their place. To improve the design of culverts and the feasibility of obtaining a permit, this study determined the maximum swimming speed that can be sustained by a fish for a period of ten minutes. This speed, known as the critical velocity, is equivalent to traversing a 100m culvert. The critical velocities were determined for the following fish species native to the piedmont of North Carolina: Nocomis leptocephalus, Lepomis auritus, Etheostoma nigrum, Lepomis macrochirus, Noturus insignis, Notropisprocne. The fish were collected by electrofishing from local streams. After resting for 12 to 18 hours the fish were placed in a flume and allowed to accommodate at a resting velocity of 20cm/s. The velocity was then increased by 10cm/s every ten minutes, while returning to the resting velocity for five minutes between each step. The critical velocities for each species were 85.56cm/s, 43.89cm/s, 67.76cm/s, 37.05cm/s, 48.67cm/s, 61.42cm/s respectively. Based on the data collected in this experiment, it is recommended that the maximum velocity in a culvert be kept under 55cm/s for 90% of the fish migration period.

A one hectare pond on the headwaters of a mercury-contaminated creek in Oak Ridge, Tennessee acted as a biochemical reactor for the production of methylmercury, increasing waterborne methylmercury concentrations in the stream below the pond discharge. The flow of the creek was diverted around the pond in order to eliminate this input. Waterborne total mercury, methylmercury, and mercury in fish, were monitored in the pond and stream before and after bypass. Waterborne methylmercury concentration in the creek downstream from the pond decreased over 800% following diversion of streamflow around the pond, but mercury in redbreast sunfish in the pond tailwater did not decline similarly. Within the pond, now isolated from fresh waterborne mercury inputs from the stream, methylmercury concentrations in the water column remained similar to levels present before bypass. However, mercury concentrations in sunfish in the pond decreased approximately 75% following bypass, despite the continued presence of highly contaminated sediments (approximately 50 mg Hg/kg dry weight). We concluded that a decrease in the fraction of 'dissolved methylmercury' in the isolated pond relative to pre-bypass conditions explained the decrease in mercury in fish within the pond. That observation also indicates that mercury associated with pond sediments was relatively unavailable for eventual bioaccumulation when compared to 'fresh' mercury contributed by upstream sources. The lack of a post-bypass decrease in mercury concentrations in tailwater fish was also likely to be associated with the particle-associated nature of waterborne methylmercury exported from the pond.

Levels of contaminants in fish are of considerable interest because of potential effects on the fish themselves, as well as on other organisms that consume them. In this article we compare the mercury levels in muscle tissue of 11 fish species from the Savannah River, as well as selenium levels because of its known protective effect against mercury toxicity. We sampled fish from three stretches of the river: upstream, along, and downstream the Department of Energy's Savannah River Site, a former nuclear material production facility. We test the null hypothesis that there were no differences in mercury and selenium levels in fish tissue as a function of species, trophic level, and location along the river. There were significant interspecific differences in mercury levels, with bowfin (Amia calva) having the highest levels, followed by largemouth bass (Micropterus salmoides) and pickerel (Esox niger). Sunfish (Lepomis spp.) had the lowest levels of mercury. As expected, these differences generally reflected trophic levels. There were few significant locational differences in mercury levels, and existing differences were not great, presumably reflecting local movements of fish between the sites examined. Selenium and mercury concentrations were positively correlated only for bass, perch (Perca flavescens), and red-breasted sunfish (Lepomis auritus). Mercury levels were positively correlated with body mass of the fish for all species except American eel (Anguilla rostrata) and bluegill sunfish (L. macrochirus). The mercury and selenium levels in fish tissue from the Savannah River are similar to or lower than those reported in many other studies, and in most cases pose little risk to the fish themselves or to other aquatic consumers, although levels in bowfin and bass are sufficiently high to pose a potential threat to high-level consumers.

Sunfish and a minnow species were used as indicators of anthropogenic mercury contamination in an east Tennessee stream system receiving multiple point and non-point discharges. The monitoring of bluegill (Lepomis macrochirus) and redbreast sunfish (Lepomis auritus) identified bioavailable mercury near three geographically separate industrial facilities, and was able to detect decreases in contamination with distance away from these facilities. In general, total mercury concentrations in the tissue of sunfish in this study were low in comparison to the most commonly cited human health threshold limits, although concentrations at some sites exceeded 1 μg/g. Caged blacknose dace (Rhinichthys atratulus) were monitored in conjunction with resident fish as an indicator of more discrete sources in selected headwater streams where fish movement was deemed a potential factor affecting mercury body burdens. Mercury concentrations in muscle tissue of caged dace after 12 weeks exposure were generally low (

A study of hydrologic conditions, vegetation, and fishes was made in the Ochlockonee River and flood plain in northwest Florida from 1987 to 1989. The study was conducted by the U.S. Geological Survey in cooperation with the Florida Game and Fresh Water Fish Commission to document the importance of the flood-plain environment to fishes. A total of 8,225 fish belonging to 15 families and 48 species was collected during the study in flood-plain, backwater, and main channel habitats by five different sampling methods. During floods, three-quarters of the fish species known to occur in the main channel were collected in the flood plain. The most frequently collected species in the flood plain during floods were weed shiner (Notropis texanus), redbreast sunfish (Lepomis auritus), brown bullhead (Ictalurus nebulosus), bluegill (Lepomis macrochirus), gizzard shad (Dorosoma cepedianum), mosquitofish (Gambusia affinis), and redear sunfish (Lepomis microlophus). The study period included a drought during which flood-plain ponds were isolated from the river for 10 to 14 months. Thirteen species found in isolated flood-plain ponds had survived low dissolved-oxygen concentrations the preceding fall. Flier (Centrarchus macropterus), pirate perch (Aphredoderus sayanus), mosquitofish, and warmouth (Lepomis gulosus) were the most frequently collected drought pond species. Seven common flood-plain species that were rare or absent in the main channel apparently depend on flood-plain, backwater, and tributary habitats for their survival in this river system: flier, banded pygmy sunfish (Elassoma zonatum), bluespotted sunfish (Enneacanthus gloriosus), least killifish (Heterandria formosa), taillight shiner (Notropis maculatus), redfin pickerel (Esox americanus americanus}, and brown bullhead. The annual flood season of the Ochlockonee River typically occurs in January, February, March, and April. Summer floods are common but usually of shorter duration than winter-spring floods. Typical range in stage is 16 feet from the low to the high for the year. Alluvial flood-plain processes such as erosion and sediment deposition create topographic relief on the flood-plain surface that allows diverse habitats to develop. Riverbank levees and terraces serve as berms during low and medium river stages, separating still-water habitats in ponds and depressions from the flowing waters of the main channel. During high river stage, all areas of the flood plain are covered with flowing water. Tree communities were distinctly different in each topographic zone, reflecting the varied hydrologic conditions existing within the flood plain. High terraces supported a mixture of canopy species including spruce pine (Pinus glabra), sweetgum (Liquidambarstyraciflua), live oak (Quercus virginiana), and water oak (Quercus nigra), and were flooded an average of 2 to 3 weeks a year from 1931 to 1989. Low terraces, dominated by a canopy of swamp laurel oak (Quercus laurifolia), were normally flooded a total of 2 to 4 months a year. The dominant canopy species in depressions was Ogeechee tupelo (Nyssa ogeche), with bald-cypress (Taxodium distichum) the most common associate. Depressions were typically flooded by the river a total of 3 to 5 months a year, but water was often trapped in these areas long after floods receded. Live and dead vegetative structure in the flood plain, and the amount of time it was flooded, varied with topographic zone and season. The fluctuating hydrologic conditions of the river-flood-plain system, along with the variety of alluvial features and tree communities, contribute to diversity in the fish community. During low water, flood-plain ponds support a fish community distinctly different from that of flowing waters of the main channel. During high water, flood-plain ponds mix with flood waters, and all river-flood-plain fishes gain access to diverse forest habitats.

Myxobolus paralintoni Li and Desser, 1985, is redescribed from infected cardiac tissue of redbreast sunfish. Lepomis auritus Linnaeus, from the Potomac River in Montgomery County, Maryland. Mature and developing spores were contained within trophozoites from the collagenous connective tissues of the bulbus arteriosus. Two distinct trophozoites types were found; a thick-walled cyst and a relatively thin-walled "compartmentalized" cyst. Mature spores measure 11.7 13.5 microns in length and 9.0-10.6 microns in width. Polar capsule length and width are 4.5-6.5 microns and 2.7-3.8 microns, respectively, with no intercapsular process present. The sutural ridge had 8-11 triangular folds and the sporoplasm contained a large iodinophilous vacuole. Spores of M. paralintoni are compared with other morphologically similar species of Myxobolus reported from North America.

Two types of third-stage nematode larvae (most of which were encapsulated) were collected from the abdominal cavity and liver of the freshwater fishes Etheostoma fonticola, Etheostoma lepidotum, Cichlasoma cyanoguttatum, Lepomis auritus, Lepomis sp., and Gambusia affinis in Texas and are referred to the genus Falcaustra. This is the first record of Falcaustra larvae from fishes, and their presence may reflect the importance of fishes as paratenic hosts of turtle parasites in this genus.

Movements by adult Percina nigrofasciata and juvenile Lepomis auritus were examined in a large Coastal Plain stream in the southeastern United States. I marked fishes with subcutaneous injections of acrylic paints to indicate capture location within a 550-m long study site. Recaptures over an 18-month period primarily occurred within 33 m of the original capture location, suggesting longterm residence in relatively small areas. However, 11 Percina and three Lepomis moved at least 100 m (maximum distance moved = 200 m for Lepomis, 420 m for Percina), and individuals of both species shifted between distinctly different mesohabitats (boulder riffle, sand pool, and gravel riffle). Distance moved did not strongly relate to time between captures. Long-distance movements (> 33 m) by Percina mostly occurred from Nov. through June. The winter and springtime movements by darters occurred in upstream and downstream directions and into all three mesohabitats, and at least 40% of these movements were unassociated with periods of extreme high flow. Periodic long-range movements may allow small fishes to respond to variation in resources over a large area and across a variety of stream habitats.

Age-specific habitat segregation and localized migrations to spawning grounds were noted in Notropis cummingsae (dusky shiner) in the Savannah River drainage, South Carolina. Notropis cummingsae spent most of their adult lives associated with noticeable current, usually in scour pools or eddies. Slow, still pools were used for spawning and larval rearing. The young N. cummingsae remained in the pools until juveniles, then joined the adults in faster water. Within pools, N. cummingsae spawned in the nests of Lepomis auritus (redbreast sunfish). The L. auritus defended their nests from N. cummingsae, but the symbionts accessed the nest primarily when the guarding male host was away from the nest or preoccupied with another centrarchid. While on the spawning grounds, N. cummingsae fed voraciously on eggs within the centrarchid nests. Gut content analysis of these N. cummingsae indicated that they ate almost exclusively centrarchid eggs/larvae even though eggs/larvae of both species were in the nest. A mean of up to 9.2 larvae was eaten per N. cummingsae, and from 15 to over 100 individuals were observed in a nest at one time. Predation of eggs/larvae by N. cummingsae appears to reduce the reproductive success of the host, resulting in a parasitic nest association, but more detailed research is necessary to determine this unequivocally.