Exposure to a common urban pollutant affects the survival and swimming behaviour of creek chub (Semotilus atromaculatus)

Anthropogenic effects on the aquatic environment are ever present and ever increasing and while a plethora of aquatic contaminants are known to affect fishes, one ubiquitous and increasingly prevalent world-wide urban runoff pollutant is frequently disregarded, and that is pet waste. While dog waste has been identified as a significant factor contributing to bacteria and nutrient loading within receiving waters and the associated water quality changes are known to affect fishes, the impact of uncollected dog faeces on urban fish populations has never been directly investigated. In this study we exposed creek chub (Semotilus atromaculatus), a widespread tolerant stream minnow, to various realistic concentrations of dog waste as simulated urban park runoff testing both fresh and dried dog faeces in both stagnant and aerated water for 96 h to investigate the impact on fish survival and behaviour. Creek chub percentage mortality increased significantly relative to controls and across an exposure gradient and was likely caused by anoxic conditions. Survivors were initially smaller while those that died were initially larger and presented with abnormal abdominal subdermal lesions post-exposure. Additional indicators of physiological stress included significantly increased rates of aquatic surface respiration and changes in flume test derived swimming motivation metrics with increased exposure concentrations. Both mortality and behavioural responses were alleviated by aeration. Furthermore, trials with fresh and dried faeces differed only in time-to-death and swimming metrics where results from dried trials were similar to those from aerated experiments. Results demonstrated the impact that the global dog waste management problem can have on aquatic communities with effects on creek chub likely to be more severe for less pollution-tolerant species and also likely to be exacerbated under future scenarios that consider climate change and increased urbanization.     

Multi‐scale effects of impoundments on genetic structure of creek chub (Semotilus atromaculatus) in the Kansas River basin

1. Habitat fragmentation has been implicated as a primary cause for the ongoing erosion of global biodiversity, yet our understanding of the consequences in lotic systems is limited for many species and regions. Because of harsh environmental conditions that select for high colonisation rates, prairie stream fishes may be particularly vulnerable to the effects of fragmentation. Hence, there is urgent need for broader understanding of fragmentation in prairie streams such that meaningful conservation strategies can be developed. Further, examination at large spatial scales, including multiple impoundments and un‐impounded catchments, will help identify the spatial extent of species movement through the landscape. 2. Our study used data from 10 microsatellite loci to describe the genetic structure of creek chub (Semotilus atromaculatus) populations across four catchments (three impounded and one un‐impounded) in the Kansas River basin. We investigated whether genetic diversity was eroded in response to habitat fragmentation imposed by reservoirs and whether intervening lentic habitat increased resistance to dispersal among sites within a catchment. 3. Our analyses revealed that genetic diversity estimates were consistent with large populations regardless of the location of the sampled tributaries, and there was little evidence of recent population reductions. Nevertheless, we found a high degree of spatial genetic structure, suggesting that catchments comprise a set of isolated genetic units and that sample sites within catchments are subdivided into groups largely defined by intervening habitat type. Our data therefore suggest that lentic habitat is a barrier to dispersal among tributaries, thus reducing the opportunity for genetic rescue of populations in tributaries draining into reservoirs. Isolation by a reservoir, however, may not be immediately deleterious if the isolated tributary basin supports a large population.     

Age structure and growth of Semotilus atromaculatus(Mitchill) in PCB‐contaminated streams

Creek chub Semotilus atromaculatus from two PCB contaminated streams (Clear Creek and Richland Creek) at three locations and a reference stream (Little Indian Creek), Indiana, U.S.A., were examined to determine if age class structure and growth variables were correlated with in‐situ PCB exposure. Approximately five to 15 fish were captured weekly during the spring spawning season and monthly thereafter for a 12 month period. Fish collected ranged from 25 to 267 mm total length (L_T). Throughout the course of this study, no spawning activity was observed at either location in Clear Creek, although some very small young‐of‐the‐year (YOY) creek chub fry were observed at the downstream location by late summer. Creek chub nests were observed in both Richland Creek and Little Indian Creek but YOY were common only in Little Indian Creek. Exposure to PCBs was shown to both enhance and decrease growth in varied laboratory tests; subtle but significant gender‐specific differences in the growth of creek chub populations between the sites were observed. Creek chub up to 24 months in age from Clear Creek and Richland Creek were significantly larger (both L_T and mass for males and L_T for females) than reference site creek chub. This trend was reversed for creek chub aged ≥24 months as the reference site fish were consistently larger with reference males weighing significantly more. Older age classes of creek chub were missing in areas of higher PCB contamination. Female population growth rates and individual instantaneous growth rates were consistently higher at the reference site in comparison to the PCB‐contaminated sites. Calculation of ‘functional b’(as a condition factor) did indicate that growth enhancement in young males did occur at the most contaminated site and reductions in growth (mass relative to L_T) occurred in females from all contaminated sites. Furthermore, long‐term survivorship for females was reduced in the PCB‐contaminated streams. All of these subtle alterations in growth would not have been observed if males and females had not been analysed separately.     

Characterization of 16 highly variable tetranucleotide microsatellite loci for Oregon chub (Oregonichthys crameri) and cross amplification in Umpqua chub (O. kalawatseti)

We describe the isolation and development of 16 polymorphic tetranucleotide microsatellite loci for the endangered Oregon chub (Oregonichthys crameri). Two loci appear to be duplicated. For the remaining 14 loci, we observed between three and 19 alleles per locus in a sample of 42 fish. Thirteen of these loci were also polymorphic in the closely related Umpqua chub (O. kalawatseti). These loci will aid in our understanding of the molecular ecology and conservation of these two species.     

Spatial heterogeneity in the parasite communities of creek chub (Semotilus atromaculatus) in southeastern Nebraska

The intestinal helminth communities of creek chub (Semotilus atromaculatus) were studied in the streams of southeastern Nebraska to characterize spatial variation, to determine whether drainages act as regional species pools, and to examine the spatial patterning of individual parasite species within and among drainages. Creek chub were sampled in the summer of 2003 and the spring of 2004 at each of 12 sites distributed evenly among 3 drainages in the Big Nemaha River watershed. Four intestinal helminths were recovered: Allocreadium lobatum, Proteocephalus sp., Rhabdochona canadensis, and Paulisentis missouriensis. Host size had little or no effect on the composition of the parasite communities of creek chub, either among individual fish or among samples. In contrast, drainage and sample date explained 82% of the variation in mean infracommunity species richness among samples, and 62% of the variation in mean infracommunity abundance among samples. Drainage differences were determined by the distributions of P. missouriensis and R. canadensis; whereas, A. lobatum and Proteocephalus sp. were more uniformly distributed among drainages. Each drainage was characterized by a unique pattern of species diversity at infracommunity, component community, and drainage levels of organization.     

Effects of dynamic landscape elements on fish dispersal: the example of creek chub (Semotilus atromaculatus)

Barriers along a watercourse and interconnections between drainage systems are dynamic landscape elements that are expected to play major roles in the dispersal and genetic structure of fish species. The objective of this study was to assess the role of these elements using creek chub ( Semotilus atromaculatus ) in the Mastigouche Wildlife Reserve (Québec, Canada) as model. Numerous impassable waterfalls and interconnections among drainage systems were inferred with geographic information systems and confirmed de visu . The analysis of 32 populations using seven nuclear microsatellites revealed the presence of three genetically distinct groups. Some groups were found upstream of impassable barriers and in adjacent portions of distinct drainage systems. Admixture among groups was also detected in some populations. Constraining phylogenetic procedures as well as Mantel correlation tests confirmed that the genetic structure is more likely to result from interconnections between the drainage systems than from the permanent network. This study indicates that landscape elements such as interconnections are of major importance for circumventing impassable barriers and colonizing lakes that are otherwise inaccessible. Such an approach could be relevant for determining the origins of fish species (i.e. native vs. introduced) in the context of conservation.     

Microsatellite loci in the Lahontan tui chub,Gila bicolor obesa,and their utilization in other chub species

Primers were developed for 17 microsatellite loci from an enriched (GATA)_n library from DNA from Gila bicolor obesa. These primers were tested for cross‐species amplification in Gila bicolor snyderi, Gila orcutti and Gila coerulea.     

Characterization of 32 novel microsatellite loci for population and mating system studies using Campostoma anomalum (central stoneroller)

The central stoneroller (Campostoma anomalum) is an abundant, widespread and sexually dimorphic stream minnow that is a useful model for mating system studies as well as a sentinel species for understanding population-level processes for fishes in headwater communities. We developed one genomic library enriched for dinucleotide repeats and isolated 48 putative, novel microsatellite loci. Of those, we present 32 polymorphic and independent microsatellite markers with 3 to 16 alleles per locus and heterozygosity ranging from 0.23 to 0.95. Hence, these markers will be useful for future behavioural, ecological and evolutionary studies using C. anomalum.     

Shifting thermal regimes influence competitive feeding and aggression dynamics of brook trout (Salvelinus fontinalis) and creek chub (Semotilus atromaculatus)

The natural distributions of freshwater fish species are limited by their thermal tolerances via physiological constraints and increased interspecific competition as temperatures shift toward the thermal optima of other syntopic species. Species may mediate stress from temperature change physiologically, behaviorally, or both; but these changes may compromise competitive advantages through effects on feeding and social behavior. In the Appalachian Mountains of North America, creek chub (Semotilus atromaculatus) are found in warm‐water and cold‐water streams and overlap in range with brook trout (Salvelinus fontinalis) across lower thermal maxima, where they compete for food and space. As stream temperatures continue to increase due to climate change, brook trout are under increasing thermal stress which may negatively affect their ability to compete with creek chub. To examine the influences of temperature on competitive interactions between these species, we observed feeding behavior, aggression, and habitat use differences at three temperatures approaching brook trout thermal maxima (18°C, 20°C, and 22°C) among dyad pairs for all combinations of species in experimental flow‐through tanks. We also examined feeding and habitat use of both species under solitary conditions. We found as temperature increased, feeding and aggression of brook trout were significantly reduced in the presence of creek chub. Creek chub pairs were more likely to occupy benthic areas and refugia while brook trout pairs used surface water more. Space use patterns significantly changed by pairing treatment. Aggression and space use shifts allowed increased exploitative and interference competition from creek chub when paired with brook trout that was not present in conspecific pairs. The decreased dominance of a top predator may lead to diverse impacts on stream community dynamics with implications for the future range restriction of brook trout and demonstrate possible mechanisms to facilitate competitive advantages of warm water generalist species under thermal stress.     

Characterization of microsatellite loci in longnose dace (Rhinichthys cataractae) and interspecific amplification in five other Leuciscinae species

The longnose dace (Rhinichthys cataractae) appears as a relevant model to address environmental and ecological issues in an evolutionary perspective. Eleven microsatellite markers were characterized for this species. Eight of these loci were highly polymorphic for populations of this species. Between four to 10 loci were also successfully amplified in five closely related species. These markers are believed to be valuable tools for genetic analysis of populations of longnose dace and other Leuciscinae species.     

Characterization of 35 novel microsatellite loci for ecological and evolutionary studies of the bluntnose minnow (Pimephales notatus)

The bluntnose minnow (Pimephales notatus) is abundant and widespread with a broad ecological niche. This species is also sexually dimorphic with strong competition between males during the mating season. We developed two genomic libraries enriched for microsatellite repeats - one dinucleotide and one tetranucleotide - and isolated 48 putative, novel microsatellite loci. Of those, we present 35 polymorphic and statistically independent microsatellite markers with two to 18 alleles per locus and heterozygosities ranging from 0.04 to 1. These markers will be useful for future behavioural, ecological, evolutionary and mating system studies using P. notatus.     

Ontogenetic changes in diel activity,food habits and spatial distribution of juvenile and adult creek chub,Semotilus atromaculatus

Synopsis Juvenile creek chub, Semotilus atromaculatus, differed ecologically from adults. They were essentially diurnal, fed on small prey (adult diptera and aquatic adult coleoptera) and were found mainly in shallow littoral water (0.8 m depth) of a Québec oligotrophic lake. In contrast, adults were principally nocturnal, fed on larger prey (Gammaridae, diptera larvae, diptera pupae and ephemeroptera larvae) and were found in deeper water (1.2, 2.0 and 2.9 m depth). The overlap in diet between juvenile and adult fish was 10 percent. We found that predation by brook charr, Salvelinus fontinalis, upon creek chub was low, as only 5 chart stomachs of the 302 examined contained a total of 16 juvenile chub and none contained adult chub. Laboratory observations revealed that under low light intensity (0.17 lux) adult creek chub fed as efficiently as under high light intensity (22 lux). Several possible hypotheses to explain the evolution of the two different strategies exhibed by adult and juvenile creek chub are discussed.     

Isolation of microsatellite loci in the freshwater fish,the bitterling Rhodeus sericeus (Teleostei: Cyprinidae)

We isolated 30 microsatellites from the freshwater fish, the bitterling Rhodeus sericeus. Twenty‐three microsatellite sequences possessed sufficient flanking DNA from which to design primers. Twelve loci were characterized and all were found to be polymorphic. These loci were isolated and characterized as part of a project to investigate the consequences of male alternative mating tactics and sperm competition using the bitterling as a model species.     

The photic environment and scotopic visual pigments of the creek chub,Semotilus atromaculatus and white sucker,Catostomus commersoni

Summary Scotopic visual pigments measured in the creek chub and the white sucker are porphyropsins with mean _max values located at 538.3 and 536.5 nm, respectively. There is a shift of the _max towards shorter wavelengths during the winter in both of these species coinciding with similar changes in the quality of downwelling light. _max is significantly correlated to the P₅₀ and spectrum width of the downwelling light and dissolved oxygen. An analysis of variance shows that there are significant differences between the _max values of: fish in the two lakes, fish at different times, the two species at different times and fish in different lakes at different seasons. The offset visual pigments of both species appear to be well adapted to their photic environment in terms of the contrast hypothesis. This improvement of contrast detection is discussed in relation to their feeding habits.Abbreviations _max wavelength at which absorbance is maximum - P₅₀ wavelength which halves the total number of photons between 400 and 700 nm, a measure of spectral quality - PAR photosynthetically active radiation - MSP microspectrophotometric - SE standard error     

Characterization of nine microsatellite loci in impala (Aepyceros melampus)

Nine microsatellite loci were isolated from a genomic DNA library created from impala (Aepyceros melampus). Observed and expected levels of heterozygosity were computed utilizing 25 individuals from a population in central Kenya. Tests for Hardy–Weinberg equilibria were conducted and found that three of the nine loci deviated from equilibrium in this population. These markers were developed to analyse the genetic effects of culling and isolation on a game preserve in Kenya.     

Characterization of microsatellite loci in the lesser dawn bat (Eonycteris spelaea)

We constructed a genomic DNA library enriched for CA repeat motifs in Eonycteris spelaea. Nine microsatellite loci were isolated and tested on a population of 39 samples from Yunnan Province, China. These nine loci had three to 22 alleles per locus. Observed and expected heterozygosity values ranged from 0.079 to 0.963 and from 0.078 to 0.959. Two loci revealed significant departure from Hardy-Weinberg equilibrium and no linkage disequilibrium was found between loci pairs. These microsatellites can be a powerful molecular tool for population-level studies of E. spelaea.     

Characterization of microsatellite loci isolated in trumpeter swan (Cygnus buccinator)

Primers for 16 microsatellite loci were developed for the trumpeter swan (Cygnus buccinator), a species recovering from a recent population bottleneck. In a screen of 158 individuals, the 16 loci were found to have levels of variability ranging from two to seven alleles. No loci were found to be linked, although two loci repeatedly revealed significant departures from Hardy–Weinberg equilibrium. Amplification in the closely related tundra swan (Cygnus columbianus) was successful for all except one locus. These microsatellite loci will be applicable for population genetic analyses and ultimately aid in management efforts.     

Characterization of microsatellite loci isolated in Mountain Plover (Charadrius montanus)

Primers for 15 microsatellite loci were developed for Mountain Plover, a species whose distribution and abundance have been reduced drastically in the past 30 years. In a screen of 126 individuals collected from four breeding locales across the species’ range, levels of polymorphism ranged from two to 13 alleles per locus. No two loci were found to be linked, although one locus revealed significant departures from Hardy–Weinberg equilibrium. These microsatellite loci can be used in population genetic studies, ultimately aiding in management efforts for Mountain Plover. Additionally, these markers can potentially be used in studies investigating the mating system of Mountain Plover.     

Effects of an experimental short‐term cortisol challenge on the behaviour of wild creek chub Semotilus atromaculatus in mesocosm and stream environments

The consequences of stress on the behaviour of wild creek chub Semotilus atromaculatus outside the reproductive period were studied using a single intra‐coelomic injection of cortisol, suspended in coconut butter, to experimentally raise plasma cortisol levels. Behaviour between cortisol‐treated, sham‐treated (injected with coconut butter) and control S. atromaculatus was compared in a mesocosm system, using a passive integrated transponder array, and in a natural stream system (excluding shams), using surgically implanted radio transmitters. While laboratory time‐course studies revealed that the cortisol injection provided a physiologically relevant challenge, causing prolonged (c. 3 days) elevations of plasma cortisol similar to that achieved with a standardized chasing protocol, no differences in fine‐scale movements were observed between cortisol‐treated, sham‐treated and control S. atromaculatus nor in the large‐scale movements of cortisol‐treated and control S. atromaculatus. Moreover, no differences were observed in diel activity patterns among treatments. Differential mortality, however, occurred starting 10 days after treatment where cortisol‐treated S. atromaculatus exhibited nearly twice as many mortalities as shams and controls. These results suggest that, although the experimental manipulation of cortisol titres was sufficient to cause mortality in some individuals, there were compensatory mechanisms that maintained behaviours (i.e. including activity and movement) prior to death. This study is one of the first to use experimental cortisol implants outside a laboratory environment and during the non‐reproductive period and yields insight into how wild animals respond to additional challenges (in this case elevated cortisol) using ecologically meaningful endpoints.     

Characterization of 11 new microsatellite loci in taro (Colocasia esculenta)

Eleven new microsatellite markers were isolated from taro, Colocasia esculenta (L.) Schott, a root crop widely distributed all over the world. Forty-eight primer pairs were designed from a microsatellite-enriched genomic library, of which 11 primer pairs have polymorphisms in 30 individuals tested from a population in China, which revealed two to six alleles per locus with the observed and expected heterozygosity levels ranging from 0 to 0.733 and from 0.381 to 0.731, respectively. These new genetic markers will be useful for the study of taro germplasm management and population evolution in the future.