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Human activity can put non-game fishes at higher risk of extinction because of inappropriate management action. Eastern sand darter (Ammocrypta pellucida), a small benthic fish classified as threatened across much of its northern range, inhabits increasingly fragmented sandy habitats and, as a non-game fish, may be easily overlooked in conservation efforts. In this study, the authors use genotype data from nine microsatellite loci and cytochrome oxidase I (COI) sequencing data across its northern native range to re-assess genetic structure and to characterize a newly discovered, geographically disjunct population. Previous microsatellite marker analyses had identified seven distinct population genetic clusters across the region sampled; the analysis of this study showed that the newly discovered population (West Lake, Ontario) exhibits a divergent structure. COI haplotype analysis suggests that a single haplotype recolonized the Great Lakes and surrounding water bodies after the Wisconsinan glacial period, and subsequent fluctuation in water levels and habitat fragmentation resulted in divergence of genetic clusters. Although the novel West Lake population has a common ancestral source with other populations in the broader region, its divergent genetic signature merits its consideration as a separate conservation unit. The analyses of this study highlight the potential conservation implications of the discovery of new populations, particularly those of at-risk species, even within a region that has been genetically well characterized.

The use of translocations to recover populations requires a sufficiently large number of individuals from source populations, but removing too many individuals could lead to source population collapse. To understand the trade-off between the probabilities of source population extirpation and translocation success, matrix population models that incorporate Allee effects, density dependence, and demographic and environmental stochasticity were combined with a model that simulates removals from source populations. We apply these models to eastern sand darter (Ammocrypta pellucida; Species at Risk Act status: Threatened) translocation scenarios in Canada. The results suggest that translocations most often require source populations >20 000 individuals, as source population extirpation probability increased with the number and frequency of removals. Transport mortality or losses immediately following introduction further affected translocation success. Uncertainty around life-history parameters and the strength of Allee effects led to additional uncertainty about the required source population size. Although stochastic processes affected the probability of translocation success, factors such as stocking density and frequency can be controlled, and translocation may therefore be a viable strategy for eastern sand darter recovery, even when applying cautious thresholds to guard against uncertainty.

The dragonfly Leucorrhinia pectoralis was recorded in Slovakia at 38 sites in 112 findings and there were 707 imagoes. Reproduction was confirmed in seven sites by finding of 35 larvae and exuviae. The highest number of sites with the occurrence of L. pectoralis is located in the Záhorská nížina lowland; most sites in Slovakia are located at an altitude of 213–351 m. L. pectoralis was recorded together with 49 species of dragonflies, and the average number of L. pectoralis was 9.56 individuals per site. It occurs in the communities as a dominant species (9.5%) together with eudominants Coenagrion puella, C. hastulatum and Libellula quadrimaculata. By non-metric multidimensional scaling (NMDS), we found a coenotic correlation to peat species Libellula quadrimaculata, Leucorrhinia rubicunda, L. dubia and Sympetrum danae. By redundancy linear analysis (RDA), we found a Monte Carlo permutation test to make a non-random contribution to the explained variability of seven factors (p = 0.012–0.034). L. pectoralis statistically significantly prefers habitats in the forest landscape (r = 0.62, p = 0.0063), the presence of vegetation (r = 0.94, p = 0.0003) and peatbogs (r = 0.61, p = 0.0058). We did not confirm a significant correlation to altitude. Based on easy determination, territoriality (especially males) and bioindicative sensitivity of larvae, L. pectoralis is accepted as an umbrella species. L. pectoralis has a high dispersion potential and is suitable for creating the meta-population character of local populations, which is important for the conservation management of the species.

Translocation, the movement of organisms for conservation purposes, can result in unintended introgression if genetic material flows between populations in new ways. The Bluemask Darter Etheostoma akatulo is a federally endangered species of freshwater fish inhabiting the Caney Fork River system and three of its tributaries (Collins River, Rocky River, and Cane Creek) in Tennessee. The current conservation strategy for Bluemask Darters involves translocating the progeny of broodstock from the Collins River (in the west) to the Calfkiller River (in the east) where the species had been extirpated. In this study, we use ddRAD sequence data from across the extant range to assess this translocation strategy in light of population structure, phylogeny, and demography. We also include museum specimen data to assess morphological variation among extant and extirpated populations. Our analyses reveal substantial genetic and phenotypic disparities between a western population in the Collins River and an eastern population encompassing the Rocky River, Cane Creek, and upper Caney Fork, the two of which shared common ancestry more than 100,000 years ago. Furthermore, morphological analyses classify 12 of 13 Calfkiller River specimens with phenotypes consistent with the eastern population. These results suggest that current translocations perturb the evolutionary boundaries between two delimited populations. Instead, we suggest that repopulating the Calfkiller River using juveniles from the Rocky River could balance conflicting signatures of demography, diversity, and divergence. Beyond conservation, the microgeographic structure of Bluemask Darter populations adds another puzzle to the phylogeography of the hyperdiverse freshwater fishes in eastern North America.

The Pearl Darter Percina aurora is an imperiled species of fish currently only found in the Pascagoula River drainage in southern Mississippi. We tested 60 microsatellite loci identified by Illumina pair-ended sequencing. Forty of these loci were polymorphic in Pearl Darters with a mean number of alleles per locus of 11.5 and mean observed and expected heterozygosity values of 0.818 and 0.805, respectively. Eleven to 17 of these loci were also polymorphic in the closely related Channel Darter P. copelandi and Coal Darter P. brevicauda. These loci should prove useful in genetic studies associated with informing future management decisions for Pearl Darters and conservation efforts in other species of darter.

Round Goby (Neogobius melanostomus) has invaded high diversity tributaries of the Laurentian Great Lakes, including those supporting multiple species of conservation concern. The extent and magnitude of ecological impacts on benthic riverine fishes is poorly understood, especially changes in diet overlap and feeding strategy. We used a before-after study design to examine the impact of Round Goby on native benthic riverine fishes, including the Threatened Eastern Sand Darter (Ammocrypta pellucida) in the Sydenham River, Ontario, Canada. To evaluate shifts in diet overlap and feeding strategy, fishes were collected with multiple gears and the direct (diet overlap with Round Goby) and indirect (diet overlap among native benthic fishes) impacts of Round Goby were assessed. Prior to the arrival of Round Goby, six ecologically significant diet overlaps occurred among the studied native benthic fishes; whereas, following arrival, 20 ecologically significant diet overlaps occurred, with 6 out of 8 species, including Eastern Sand Darter, showing significant, direct diet overlap with Round Goby. Fishes exhibiting significant diet overlap with Round Goby shifted feeding strategies to become more specialized, a change in feeding consistent with potential competitive effects. Although the long-term consequences of invasion-induced diet and feeding shifts remain poorly understood, increased competitive interactions suggested by diet overlap may be occurring between Round Goby and native benthic riverine fishes and may exacerbate the observed decline of native species.

Movement is a fundamental aspect of fish ecology, and it therefore represents an important trait to monitor for the management and conservation of fish populations. This is especially true for small benthic fish, as they often inhabit part of the catchment where their movement may be restricted by alterations to river connectivity due to human activity. Still, the movement of these small benthic fish remains poorly understood, partly because of their small size and their cryptic nature. This applies to Percilia irwini, an endangered small darter native to the south-central region of Chile. Its habitat has been affected by the presence of large hydroelectric dams and is currently threatened by the construction of several others. In this study, the authors investigated movement patterns of P. irwini from populations inhabiting different parts of the Biobío catchment, with different levels of connectivity due to natural and/or human-induced features. The authors combined chronological clustering with random forest classification to reconstruct lifelong movements from multi-elemental otolith microchemistry transects. The majority of the movements detected occurred in an undisturbed part of the catchment. These were directional upstream movements occurring between capture sites from the lower and the middle reaches of the river, representing a distance of nearly 30 km, a distance much larger than previously thought. Nonetheless, in the part of the catchment where connectivity was affected by human activity, no such movements were identified. This study shows that connectivity alteration could impede naturally occurring movement and further threaten the resilience of populations of P. irwini. Furthermore, the results presented are used to discuss advantages and disadvantages of microchemistry analysis for studying movement of small benthic fish.

Darters represent one of the most diverse groups of freshwater fishes in North America, but approximately 33% of the 215 recognized species are considered imperiled on the IUCN Red List. Discovery and description of new darter species continue at a relatively rapid pace, with many exhibiting microendemic geographic distributions and little baseline data for conservation decisions. The blueface darter Etheostoma cyanoprosopum is a newly described species that occupies

Niche specificity can predispose species to population declines during periods of resource limitation, yet trophic niche specificity is poorly known for many small-bodied freshwater fishes. Applying a two-tiered approach involving stomach content and stable isotope analyses, we examined the diet and trophic niche of the threatened eastern sand darter (Ammocrypta pellucida (Putnam, 1863)) and co-occurring fishes in the Thames River, Ontario, Canada. As with previous studies, stomach content analysis revealed that eastern sand darter consumed a variety of benthic organisms including Chironomidae, Cladocera, Ostracoda, Oligochaeta, and Ephemeroptera; however, proportional contributions of prey groups differed based on stable isotope analysis, highlighting the potential for seasonal variation in prey consumption. Despite evidence of a generalist strategy, stable isotope analysis indicated eastern sand darter exhibited a relatively narrow trophic niche relative to co-occurring fishes. Trophic niche overlap was relatively minor between eastern sand darter and drift-feeding fishes (spotfin shiner (Cyprinella spiloptera (Cope, 1867)), emerald shiner (Notropis atherinoides Rafinesque, 1818), and buffalo sp. (genus Ictiobus Rafinesque, 1820)), but was more evident between eastern sand darter and benthic and benthopelagic fishes (johnny darter (Etheostoma nigrum Rafinesque, 1820) and blackside darter (Percina maculata (Girard, 1859))), indicating that competition with these species may be more likely during periods of prey scarcity.

While population genetic structuring is easily identified, the causes of the structure can be difficult to determine. Habitat fragmentation in aquatic systems has often been identified as a major source of increased population structure and decreased genetic diversity in fish, including benthic resident species such as darters. However, these findings are often not replicated across natural and manmade barriers and come from endangered or threatened populations where the genetic structure is likely already compromised due to small population size. To evaluate the factors involved in structuring a healthy darter population, we genotyped 506 tessellated darters from 18 sites in three different river drainages and one large lake. Sites were all in the same watershed but separated from one another by one or more of three different types of barriers: dams, natural fall lines and causeways. We found that while diversity and allele frequency varied largely by drainage, within drainage variation was minimal even across multiple barriers. No single barrier type appeared to be more formidable than any other. Our results indicate that healthy populations of darters may naturally be structured by drainage, but likely disperse across barriers enough to retain drainage-wide homogeneity.

Variation in habitat across the landscape can limit dispersal between populations and influence the diversity and degree of genetic structure of populations. This effect may be larger in small aquatic species with low vagility, specific habitat requirements, and that inhabit lotic systems where dispersal may be biased by the unidirectional movement of water downstream. Darters offer a unique perspective to understand these influences because they have variable life histories and habitat requirements, and evidence suggests that certain life history characters may affect gene flow. Data were collected from a combination of microsatellite loci from 825 individuals to compare genetic structure and differentiation of three species of darters (Ammocrypta beanii, Etheostoma swaini, and Percina nigrofasciata) with differences in life histories and habitat requirements in the Pearl River basin. Our analyses reveal low, but interesting, patterns of population subdivision. Genetic subdivision among populations was highest for E. swaini, intermediate for P. nigrofasciata, and lowest for A. beanii. This pattern suggests a difference in dispersal, influenced by the variation in available habitat required for each species. Further investigations are warranted for small, benthic, and especially threatened species in the Pearl River basin as the main channel has undergone a significant shift in geomorphology and habitat diversity since the construction of reservoirs and low-head dams along its course.

The southeastern United States represents one of the richest collections of aquatic biodiversity worldwide; however, many of these taxa are under an increasing threat of imperilment, local extirpation, or extinction. The pearl darter Percina aurora is a small-bodied freshwater fish endemic to the Pearl and Pascagoula river systems of Mississippi and Louisiana (USA). The last collected specimen from the Pearl River drainage was taken in 1973, and it now appears that populations in this system are likely extirpated. This reduced the historical range of this species by approximately 50%, ultimately resulting in federal protection under the US Endangered Species Act in 2017. To better understand the current distribution and general biology of extant populations, we analyzed data collected from a series of surveys conducted in the Pascagoula River drainage from 2000 to 2016. Pearl darters were captured at relatively low abundance (2.4 ± 4.0 ind. per collection) from 57% of 308 collections. We identified strong relationships between local habitat variables and occurrence and catch-per-unit-effort (CPUE) of pearl darters. Pearl darters were frequently encountered and in greater abundance in depositional areas characterized by low-velocity habitats and finer substrates. Patterns of occurrence and CPUE were spatiotemporally variable across years; however, repeated collections from a subset of localities collected across a decade or more indicated long-term persistence and stability, suggesting population resilience throughout the Pascagoula River drainage.

North American watersheds contain a high diversity of freshwater mussels (Unionoida). During the long-lived, benthic phase of their life cycle, up to 40 species can co-occur in a single riffle and there is typically little evidence for major differences in their feeding ecology or microhabitat partitioning. In contrast, their brief parasitic larval phase involves the infection of a wide diversity of fish hosts and female mussels have evolved a spectrum of adaptations for infecting host fish with their offspring. Many species use a passive broadcast strategy: placing high numbers of larvae in the water column and relying on chance encounters with potential hosts. Many other species, including most members of the Lampsilini, have a proactive strategy that entails the use of prey-mimetic lures to change the behavior of the hosts,i.e., eliciting a feeding response through which they become infected. Two main lure types are collectively produced: mantle tissue lures (on the female’s body) and brood lures, containing infective larvae, that are released into the external environment. In this study, we used a phylogenomic approach (ddRAD-seq) to place the diversity of infection strategies used by 54 North American lampsiline mussels into an evolutionary context. Ancestral state reconstruction recovered evidence for the early evolution of mantle lures in this clade, with brood lures and broadcast infection strategies both being independently derived twice. The most common infection strategy, occurring in our largest ingroup clade, is a mixed one in which mimetic mantle lures are apparently the predominant infection mechanism, but gravid females also release simple, non-mimetic brood lures at the end of the season. This mixed infection strategy clade shows some evidence of an increase in diversification rate and most members use centrarchids (Micropterus&Lepomisspp.) as their predominant fish hosts. Broad linkage between infection strategies and predominant fish host genera is also seen in other lampsiline clades: worm-like mantle lures ofToxolasmaspp. with sunfish (Lepomisspp.); insect larvae-like brood lures (Ptychobranchusspp.), or mantle lures (Medionidusspp.,Obovariaspp.), or mantle lures combined with host capture (Epioblasmaspp.) with a spectrum of darter (Etheostoma&Percinaspp.) and sculpin (Cottusspp.) hosts, and tethered brood lures (Hamiotaspp.) with bass (Micropterusspp.). Our phylogenetic results confirm that discrete lampsiline mussel clades exhibit considerable specialization in the primary fish host clades their larvae parasitize, and in the host infection strategies they employ to do so. They are also consistent with the hypothesis that larval resource partitioning of fish hosts is an important factor in maintaining species diversity in mussel assemblages. We conclude that, taking their larval ecology and host-infection mechanisms into account, lampsiline mussels may be legitimately viewed as an adaptive radiation.

We provide a description of the Blueface Darter, Etheostoma cyanoprosopum, which is distributed in the upper Sipsey Fork of the Mobile Basin and the upper portion of the Bear Creek system in the Tennessee River Drainage. The distinctiveness of Etheostoma cyanoprosopum is assessed through analysis of morphological variation and molecular phylogenetic diversity within the Etheostoma zonistium species complex. In addition to analyzing disparity of morphometric and meristic traits, we present phylogenetic analyses of a mitochondrial gene and two nuclear genes and identify genetic clusters through analysis of 25 microsatellite loci. In the mitochondrial DNA (mtDNA) gene tree, Etheostoma cyanoprosopumis resolved as the sister lineage to a clade containing all other species of the Etheostoma zonistium complex. Etheostoma zonistium is paraphyletic with respect to both Etheostoma pyrrhogaster and Etheostoma cervus, which do not resolve as sister species in the mtDNA gene tree. The two nuclear gene trees a...

In 1932, the Tuckasegee Darter was originally described as Poecilichthys gutselli, from the Tuckasegee River (Little Tennessee River system), North Carolina. In 1968, Miller, citing perceived areas of intergradation, relegated it to a subspecies of Etheostoma blennioides. Recent authors, however, re-elevated E. gutselli to the species level without providing any supporting data. We present morphological, meristic, and nuptial male pigmentation data that support the distinctiveness of E. gutselli. Etheostoma gutselli can be distinguished from proximal populations E. blennioides newmanii in the Tennessee River system by lower lateral-line (49–63 vs. 63–81) and caudal-peduncle (18–24 vs. 23–29) scale counts and differences in nuptial male pigmentation. Etheostoma gutselli primarily is restricted to the upper (Blue Ridge) portions of the Little Tennessee and Pigeon river drainages, generally upstream of the Tennessee-North Carolina state line.

Behavioural isolation between closely related species with exaggerated male mating traits is traditionally thought to be mediated by female preference for conspecific male ornaments. The role of male mate choice in maintaining boundaries between highly sexually dimorphic species is therefore comparatively neglected. However, mounting theoretical and empirical evidence supports the existence of male mate choice both within, and increasingly, between species with exaggerated male ornaments. We therefore tested the role of male mate choice in the maintenance of species boundaries for two sexually dimorphic species of darters (Percidae: Etheostoma). Using dichotomous choice assays, we measured male preferences of sympatric species Etheosotma barrenense and Etheosotma zonale for size-matched conspecific and heterospecific females, thus reducing the possibility that males would select for general indicators of fecundity. Our results show that males of both species strongly prefer conspecific females. A comparison with published data showed that the strength of preference for conspecific mates is just as strong for males as it is for females in E. barrenense. We also estimated the relative contribution of male mate choice, female mate choice and male–male competition to behavioural isolation. We found that male mate choice contributes as much as female mate choice to total behavioural isolation and thus likely plays an important role in behavioural isolation in these sexually dimorphic species. Our results suggest that the contribution of male choice to behavioural isolation should be studied in a larger variety of animal species to appreciate the relative roles of the sexes in the maintenance of species boundaries.

Headwater fishes in the southeastern United States make up much of the fish biodiversity of the region yet many are imperiled. Despite this, the specific habitat requirements of imperiled headwater fishes in lowland Coastal Plain streams have rarely been quantified. Using data collected over three years of seasonal sampling we provide estimates of the microhabitat requirements of the imperiled Yazoo darter (Etheostoma raneyi Suttkus and Bart), a small benthic insectivore. Our results indicate that the species is a microhabitat specialist and that optimum microhabitat within degraded contemporary streams consists of a narrow range of water depths (about 20–30 cm), current velocity ≥ 0.25 m·s−1, complex stable debris piles, rooted macrophytes, and likely coarse substrate. No pronounced or generalized seasonal shifts in microhabitat use occurs, and no evidence exists for intraspecific partitioning of microhabitat. Though stable and complex instream cover is one of the most important variables explaining variation in microhabitat use by Yazoo darters, such cover is rare in the degraded streams within the range of the species. Current conservation classifications of the Yazoo darter by governmental agencies and nongovernmental organizations as well as associated management plans that are based on the assumption that Yazoo darters are habitat generalists should be reviewed in recognition of the increased risk of decline because Yazoo darters are microhabitat specialists. These considerations should also be extended to other closely related imperiled species of snubnose darters.

Population monitoring is an essential component of endangered species recovery programs. The federally endangered Diamond Darter Crystallaria cincotta is in need of an effective monitoring design to improve our understanding of its distribution and track population trends. Because of their small size, cryptic coloration, and nocturnal behavior, along with limitations associated with current sampling methods, individuals are difficult to detect at known occupied sites. Therefore, research is needed to determine if survey efforts can be improved by increasing probability of individual detection. The primary objective of this study was to determine if there are seasonal and diel patterns in Diamond Darter detectability during population surveys. In addition to temporal factors, we also assessed five habitat variables that might influence individual detection. We used N-mixture models to estimate site abundances and relationships between covariates and individual detectability and ranked models using...

In the Central United States, the Arkansas darter (Etheostoma cragini) is listed as a threatened fish species by the State of Kansas. Survival of the darter is threatened by loss of habitat caused by changing streamflow conditions, in particular flow depletion. Future management of darter populations and habitats requires an understanding of streamflow conditions and how those conditions may have changed over time in response to natural and anthropogenic factors. In Kansas, streamflow alteration was assessed at 9 U.S. Geological Survey streamgages in 6 priority basins with no pronounced long-term trends in precipitation. The assessment was based on a comparison of observed (O) and predicted expected (E) reference conditions for 29 flow metrics. The O/E results indicated a likely or possible diminished flow condition in 2 basins; the primary cause of which is groundwater-level declines resulting from groundwater pumping for irrigated agriculture. In these 2 basins, habitat characteristics adversely affected by flow depletion may include stream connectivity, pools, and water temperature. The other 4 basins were minimally affected, or unaffected, by flow depletion and therefore may provide the best opportunity for preservation of darter habitat. Through the O/E analysis, anthropogenic streamflow alteration was quantified and the results will enable better-informed decisions pertaining to the future management of darters in Kansas.

Increased turbidity and the resulting decreases in water clarity have been shown to alter fish foraging behaviors in potentially detrimental ways. Given the ecological importance of darters of the genus Etheostoma and their dependence on visual cues, we examined the impact of a range of turbidity levels (3.5, 6, 10, 20, 22, and 25 nephelometric turbidity units [NTU]) on the number of prey consumed by the Tessellated Darter Etheostoma olmstedi. While a study of the Fountain Darter E. fonticola found that turbidity affected prey consumption at slightly elevated levels (≥8.7 NTU), we found no significant differences in consumption by the Tessellated Darter across turbidity levels. While there may be intragenus variation in the use of olfactory cues, another and perhaps more likely explanation is the difference in long-term exposure to a range of turbidities. The Fountain Darter is endemic to clear, primarily spring-fed rivers, whereas the Tessellated Darter is, comparatively speaking, a generalist th...

An increasing body of research shows the ability of parasites to alter the reproductive condition of their hosts, and the hosts' capacity to shift resources allocated to reproduction in response to parasitism. Here we compare host reproductive condition to gill parasite infection load in Fantail Darters (Etheostoma flabellare) of Mill Creek, Tennessee, USA, over the course of a year. We sought to determine whether host reproductive season or condition correlated with parasite load, whether parasite load differed between host sexes, and whether parasite load correlated with clutch size in females. We sampled the host population bimonthly and measured host physical and reproductive characteristics and gill parasite load. Infection levels significantly decreased when host reproductive activity ceased. Parasite load did not correlate strongly with body size in either sex. Male hosts were significantly more heavily infected than female hosts. No negative relationship was found between reproductive condition an...

The western sand darter, Ammocrypta clara, and the eastern sand darter, A. pellucida, are sand-dwelling fishes that have undergone range-wide population declines, presumably owing to habitat loss. Habitat use studies have been conducted for the eastern sand darter, but literature on the western sand darter remains sparse. To evaluate substrate selection and preference, western and eastern sand darters were collected from the Elk River, West Virginia, one of the few remaining rivers where both species occur sympatrically. In the laboratory, individuals were given the choice to bury into five equally available and randomly positioned substrates ranging from fine sand to granule gravel (0.12–4.0 mm). The western sand darter selected for coarse and medium sand, while the eastern sand darter was more of a generalist selecting for fine, medium, and coarse sand. Substrate selection was significantly different (p = 0.02) between species in the same environment, where the western sand darter preferred coarser substrate more often compared to the eastern sand darter. Habitat degradation is often a limiting factor for many species of rare freshwater fish, and results from this study suggest that western and eastern sand darters may respond differently to variations in benthic substrate composition.

For many imperiled fishes in the Laurentian Great Lakes basin, detection protocols and population monitoring programs are lacking. In this study, we used a repeat-sampling approach to compare the effectiveness of two seines (bag and beach) to detect and characterize the abundance of lake-dwelling populations of Eastern Sand Darter (Ammocrypta pellucida); a threatened species in Canada. Compared to the bag seine, the larger beach seine collected a greater number of Eastern Sand Darter and detected the species at more sampling sites. Model-averaged estimates of detection probability were also greater for the beach seine (p = 0.72) than bag seine (p = 0.48). A decline in catch over repeated seine hauls occurred at less than a third of the sample units. Mean capture probabilities were 0.41 in units sampled by beach seine, and 0.37 in units sampled by bag seine, when depletion occurred. Sizes of Eastern Sand Darter collected by each seine were significantly different, with fewer small (

Larval fish ecology is poorly characterized because sampling is difficult and tools for phenotypically identifying larvae are poorly developed. While DNA barcoding can help address the latter problem, &lsquo, universal&rsquo, primers do not work for all fish species. The Roanoke River in the southeastern United States includes seven darters (Family Percide: Tribe Etheostomatini). We made 393 collections of larval fishes in 2015 and 2018, examined darter larvae for morphometric and pigmentation traits, developed PCR primers amplifying darter DNA, and evaluated three gear types for collecting larval darters. Amplified DNA sequences for 1351 larvae matched archived mitochondrial cytochrome oxidase I sequences for darters occurring in the ecosystem. Larval darters were classified to genus with 100% accuracy using the ratio of pectoral fin length to body length, however, identification to species using morphometrics alone was subject to a misclassification rate of 11.8%, which can be resolved by considering pigmentation patterns. Gear-types varied considerably in their capture efficacy for larval darters, most Percina larvae were collected in drift nets. Larval Percina species appeared in the drift before Etheostoma species in both study years. Application of molecular genetic and phenotypic tools to larval fish identification can advance understanding of larval darter ecology.

Understanding how biotic and abiotic processes influence community assembly is a fundamental aim in ecology. Although spatial scales at which communities are studied may affect the relative importance of such assembly processes, spatial influences on community assembly have not been thoroughly addressed. We tested how spatial scale affects inferences of habitat filtering and competitive exclusion assembly processes in darter (Percidae: Etheostomatinae) assemblages across four temperate stream systems. We predicted competitive exclusion would influence assembly in fine-scale assemblages, and habitat filtering would be more influential as spatial scale increased. Moreover, we assumed that habitat heterogeneity would increase with scale, and consequently alleviate direct competitive exclusion acting at finer scales. Using a framework that incorporated genetic relatedness, morphological traits, and habitat use among co-occurring darter species, we identified ecological and evolutionary patterns of structure, which allowed us to elucidate processes of assembly. Based on phylogenetic structure, assemblages showed an increase in habitat filtering (i.e., increased phylogenetic clustering) as we scaled up from fine to intermediate assemblages; however, we found mixed signals for habitat filtering and competitive exclusion at the broadest spatial scale. While habitat filtering was found to have an overall high relative importance during assembly, we also found influence of competitive exclusion processes based on limited morphological similarity among co-occurring species. Our results generally support an increased influence of habitat filtering processes in broader scale assemblages. Moreover, we suggest that habitat filtering and competitive exclusion processes act simultaneously during assembly, although the relative influence of each process may be spatial-scale dependent.

Sixteen darter species, including the federally endangered Boulder Darter Etheostoma wapiti, are known to occur in the Elk River, a large, flow-regulated tributary of the Tennessee River, Tennessee–Alabama. Since the construction of Tims Ford Dam (TFD) in 1970, habitat modification caused by cold, hypolimnetic water releases and peak-demand hydropower generation has contributed to population declines and range reductions for numerous aquatic species in the main-stem Elk River. We developed Bayesian hierarchical multispecies occupancy models to determine the influence of site- and species-level characteristics on darter occurrence by using presence–absence data for 15 species collected from 39 study sites. Modeling results indicated that large-river obligate species, such as the Boulder Darter, were 6.92 times more likely to occur for every 37-km increase in the distance downstream from TFD. In contrast, small-stream species were 2.35 times less likely and cosmopolitan species were 1.88 times less ...

Ichthyoplankton can be difficult to identify due to a lack of morphological differences among closely-related species. Traditional visual identification of ichthyoplankton requires special knowledge to employ morphological keys. Accurate species-level identification is often required to support monitoring programs for those taxa that are considered valued ecosystem components in environmental assessments. DNA-based methods are gaining in popularity as an alternative to visual identification techniques, but direct comparisons of methodological performance between identification techniques are lacking. The goal of this study was to evaluate and explore the consistency between visual and DNA barcoding species-level identification methods, using a case study of larval fish caught in plankton tows at Stokes Bay, Lake Huron during the spring of 2011. Four participants served as Identifiers (3 Novice, 1 Expert) for visual identification of this multi-species set of larval fishes; including Lake Whitefish, Lake Herring, Yellow Perch, Iowa Darter, Ghost Shiner, and Rainbow Smelt. Barcoding successfully identified 51/55 (92.7%) of the larval fishes, while visual identification using a dichotomous key showed substantial variation between observers, and across family/species. There was a 93.7% consistency between visual and barcoding identification at the family level, and a 71.5% consistency level between visual and barcoding at the species level. Potential sources of error are discussed for both identification methods, leading to a recommendation for the coordinated use of both visual and barcoding identification methods to improve species-level assessments for wild ichthyoplankton samples.

Despite Alabama's exceptionally diverse freshwater fish fauna, many of its fish species face extinction. Some of the state's most imperiled species dwell within coldwater springs, but a deficit of knowledge about their ecology hampers protection efforts. The watercress darter Etheostoma nuchale is a species confined to five springs in the greater Birmingham metropolitan area. Roebuck Spring likely harbors the largest population. Its pool has been surveyed occasionally, but there had been no survey of its run, a shallow stream flowing from the pool. We investigated the darter's use of the run, its habitat preferences, and characteristics of the habitats where it is most abundant. We quantified the abundance of stream microhabitats, then estimated darter density in the stream's five most common habitats using a throw trap, a high-walled metal frame dropped in the habitat. We found darters at densities vastly exceeding typical estimates derived using seine nets. We estimated the run harbored 116,932 (79,358–155,965) darters, two-thirds of which were juveniles. The most preferred habitat was coontail Ceratophyllum demersum, a submergent plant not previously known to provide darter habitat. Coontail grew prolifically in swift currents, which was surprising given that darter habitats described previously had little to no current. Coontail provided a more structurally complex habitat than the plants of the other microhabitats studied. Our results suggest that spring runs can support substantial densities of the watercress darter if dense submergent vegetation is present.

Elaborate, sexually dimorphic traits are widely thought to evolve under sexual selection through female preference, male-male competition, or both. The orangethroat darter (Etheostoma spectabile) is a sexually dichromatic fish in which females exhibit no preferences for male size or coloration. We tested whether these traits affect individual reproductive success in E. spectabile when multiple males are allowed to freely compete for a female. The quality and quantity of male coloration were associated with greater success in maintaining access to the female and in spawning as the primary male (first male to participate). On the other hand, sneaking behavior showed little correlation with coloration. Male breeding coloration in E. spectabile may therefore demonstrate how intrasexual competition can be a predominant factor underlying the evolution of male ornaments.

Closely related animal lineages often vary in male coloration, and ecological selection is hypothesized to shape this variation. The role of ecological selection in inhibiting male color has been documented extensively at the population level, but relatively few studies have investigated the evolution of male coloration across a clade of closely related species. Darters are a diverse group of fishes that vary in the presence of elaborate male nuptial coloration, with some species exhibiting vivid color patterns and others mostly or entirely achromatic. We used phylogenetic logistic regression to test for correlations between the presence/absence of color traits across darter species and the ecological conditions in which these species occur. Environmental variables were correlated with the presence of nuptial color in darters with colorful species tending to inhabit environments that would support fewer predators and potentially transmit a broader spectrum of natural light compared to species lacking male coloration. We also tested the color preferences of a common darter predator, largemouth bass, and found that it exhibits a strong preference for red, providing further evidence of predation as a source of selection on color evolution in darters. Ecological selection therefore appears to be an important factor in dictating the presence or absence of male coloration in this group of fishes.

Small sized, man-made, perennial and primarily rain-fed ponds occur widely in the rural landscape of India. These wetlands provide suitable habitats and food resources for a wide variety of resident and migratory wetland birds. Wetland birds in six rural ponds of Kurukshetra District, Haryana, in northern India were surveyed from April 2011 to May 2014 to determine status. Point counts and direct observations were used to record bird species. Sixty-nine species of wetland birds belonging to 47 genera and 20 families were identified. Family Anatidae dominated the avifauna with 20% (n = 14) of the species found. Of the species documented, 54% (n = 37) were winter migrants, 7% (n = 5) were summer migrants and 39% (n = 27) were residents. Among recorded species, Darter (Anhinga melanogaster), Painted Stork (Mycteria leucocephala), Oriental White Ibis (Threskiornis melanocephalus) and River Tern (Sterna aurantia) are considered as near threatened; Comb Duck (Sarkidiornis melanotos), Brahminy Kite (Ha...

The importance of competition among stream salamanders and other stream vertebrates in headwater systems is understudied. We conducted a replicated artificial stream experiment to evaluate competitive interactions among three common vertebrates. In this experiment, we measured change in body condition of salamanders in the black-bellied dusky complex (Desmognathus quadramaculatus/folkertsi) in the presence of two different fish species, Common Creek Chub (Semotilus atromaculatus) and Coosa Darter (Etheostoma coosae). There was no statistically significant change in body condition between the control and darter present treatments. However, salamander body condition was significantly reduced in the presence of the creek chubs suggesting an asymmetric competitive interaction between those two species. While predation is often cited as a potential mechanism limiting the distribution of stream species, the role of interspecific competition may be just as vital. Overall, our results highlight that competition, and not solely predation, may explain why some stream salamanders are restricted to headwater reaches.

This study contrasted the influence of tertiary treated municipal wastewater effluent (MWWE) exposure on the abundance, food selection (stomach contents), and carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope signatures of Rainbow Darter ( Etheostoma caeruleum ) and Greenside Darter ( Etheostoma blennioides ) in a small receiving stream in southern Ontario, Canada. Despite tertiary treatment resulting in relatively high effluent quality, there is continued concern for environmental degradation downstream of the effluent outfall because of the relatively small size of the receiving environment and recent studies that have indicated changes occurring in relative fish abundance and stable isotope signatures. In July and August of 2009 fish and benthic invertebrate communities were examined along with analysis of δ 13 C and δ 15 N of the most common species to determine the effects of effluent exposure on the food web. Rainbow Darter increased in abundance and their δ 15 N values were enriched immediately downstream of the effluent outfall throughout the summer (July and August). In contrast, while δ 15 N of Greenside Darter followed a similar pattern in July, they were not enriched in August. The benthic community was changed immediately downstream of the outfall and the δ 15 N of invertebrates was enriched, similar to that observed in Rainbow Darter. Stomach contents of the two darter species diverged the most in the summer possibly explaining some of the changes in δ 13 C and δ 15 N among sites. It is possible that Greenside Darter fed on less enriched food downstream of the outfall, or fed outside of the effluent plume during the summer. Rainbow Darter may be able to exploit the changes in habitat and prey composition, resulting in differences in relative abundance of darters immediately downstream of the effluent outfall.

Land-use change and habitat loss are important drivers of biodiversity decline at both global and local scales. To protect species from the impacts of land-use change it is important to understand the population dynamics and habitat associations across these scales. Here we present an investigation into the survival and habitat preferences of White-faced Darter (Leucorrhinia dubia) at the local scale at Fenn’s and Whixall Moss, Shropshire, UK. We used capture-mark-recapture methods to investigate survival and used sightings of individual dragonflies along with habitat data to investigate habitat preference. We found that survival between capture-visits was very low and that White-faced Darter show a clear preference for the open moss habitat on this site. In both cases, we found that the detectability either through sightings or recaptures was potentially very low and suggest that this should be taken into account in future analyses. We suggest that this could be achieved by encouraging recorders to submit complete lists and to repeat visits to sites.

What a pleasant irony that a raptor traditionally regarded as a forest species and deemed to be headed for extinction in the last century due to loss of woodlands is now perhaps the most common backyard breeding raptor in (nonforested) cities throughout North America. Indeed, city residents commonly recount to us the dazzling flying speed of the “blue darter” in its pursuit of birds at feeders. Who would have guessed that city planners and the pervasive urban bird-feeding public conceivably (and unwittingly) contributed to the recovery of this red-eyed, blue-backed predator that is so boldly tolerant of the myriad of human activities in cities?

Percina aurolineata (Percidae: subgenus Hadropterus) (Goldline Darter) is a federally threatened species that currently exists in disjunct populations in the Coosawattee River, GA, and Cahaba River, AL. These 2 Mobile Basin drainages are home to considerable endemism, and these disjunctions may actually represent cryptic diversity within Goldline Darter. We examined sequence data from the mitochondrial cytochrome b gene (cyt b) and nuclear recombination-activation gene exon 1 (RAG1) from specimens (n = 34) collected from 4 streams in the Coosawattee River drainage and 4 streams in the Cahaba River drainage for the purpose of assessing phylogenetic structure and genetic divergence to test the hypothesis that the disjunct populations of Goldline Darter represent a single species. Specimens from each of the rivers sampled were not resolved as a clade in any analysis. For cyt b, divergence within the Coosawattee was 0.8%, divergence within the Cahaba was 0.3%, and net divergence between populations w...

Etheostoma nebra, the Buck Darter, is described as a new species endemic to the Buck Creek system of the Cumberland River drainage in Kentucky, USA. The earliest collection records of Etheostoma nebra date to 1955 and were considered a population of Etheostoma virgatum. Etheostoma nebra is delimited through morphological comparisons with Etheostoma virgatum and phylogenetic analyses using DNA sequences from a mitochondrial gene and five nuclear genes. Etheostoma nebra is distinguished from Etheostoma virgatum by a lower number of total lateral scales, fewer pored lateral scales and modally 13 compared with 12 pectoral fin rays. The two species also differ in patterns of pigmentation and nuptial male coloration. In the molecular phylogenies, Etheostoma nebra is not resolved as the sister species of Etheostoma virgatum. A review of all museum collection records of Etheostoma nebra and extensive field surveys in the Buck Creek system demonstrate a dramatic decline of the species over the past 30 yea...

Diederle, J.M., 1.8.2015. Systematic status of the Miocene darter ‘Liptornis’ hesternus Ameghino, 1895 (Aves, Suliformes, Anhingidae) from Patagonia, Argentina. Alcheringa 39, 589–594. ISSN 0311-5518.Liptornis hesternus was established by Ameghino in the late 1800s on the basis of a cervical vertebra (NHMUK-A599) from the Santa Cruz Formation (Santacrucian, South American Land Mammal Age, early Miocene, Burdigalian Stage) of Patagonia, Argentina. Although taxonomic attributions were controversial, the specimen is now confidently assigned to Anhingidae. Recently, however, L. hesternus was designated a nomen dubium because of its uninformative diagnostic characters and apparent loss of the holotype. Nevertheless, NHMUK-A599 has been relocated and is redescribed here prompting referral to Anhinga. A combination of traits are shared with the extant Anhinga anhinga and A. melanogaster, and the material is dimensionally compatible with A. anhinga. The estimated body size of NHMUK-A599 would have been larger tha...

Habitat partitioning among syntopic darter species (Percidae: Etheostomatini) was examined in the Flint River and Estill Fork of the Paint Rock River in northeast Alabama from September 2010 to September 2011. Substrate composition, depth, and water velocity were important variables by which species segregated. Niche overlap values also indicated a high degree of habitat partitioning among species at both study sites, although a substantial amount of overlap was seen between Etheostoma simoterum and Etheostoma caeruleum at the Estill Fork site. Segregation among species was present throughout the year, but the significance of differences in habitat preferences did vary seasonally, especially during the post-spawn period when habitat heterogeneity was reduced. Intra-specific variation in habitat utilization was present among some species, with males generally preferring higher flow and coarser substrates than females. Habitat segregation was a well-structured mechanism allowing the coexistence of ecologically similar species. Copyright © 2015 John Wiley & Sons, Ltd.

Environmental variation can shape phenotypic variation in organisms, but most evidence for trait differentiation comes from analyses of dichotomous habitat types that differ in only one or few key environmental factors. In reality, environmental variation is often more subtle, gradual and multifarious. Here, we investigated geographic variation in body shape of two darter species (Etheostoma spectabile and Etheostoma flabellare; Percidae) that occur along river gradients. This study addressed three specific questions: Is there intraspecific geographic variation in the two species across different sites in the Ozark Highlands of Oklahoma (USA)? Is phenotypic variation across sites correlated with abiotic environmental conditions? Do the two species share site-specific (i.e. convergent) phenotypic variation in areas where they occur together? Our results indicated significant body shape variation in both species. Population differences in body shape were particularly correlated with variation in substrate composition. The combined analysis of both species indicated a small but significant effect of convergence on body shape wherever they are sympatric; shared variation, however, was not related to any environmental variables included in the analysis. While it remains unclear whether phenotypic variation in these species is due to heritable differentiation or environmentally induced plasticity, our results indicate that even subtle and gradual environmental variation can induce substantial variation in phenotypes on a relatively small spatial scale.

It is not known how environmental pressures and sexual selection interact to influence the evolution of extravagant male traits. Sexual and natural selection are often viewed as antagonistic forces shaping the evolution of visual signals, where conspicuousness is favored by sexual selection and crypsis is favored by natural selection. Although typically investigated independently, the interaction between natural and sexual selection remains poorly understood. Here, we investigate whether sexual dichromatism evolves stochastically, independent from, or in concert with habitat use in darters, a species-rich lineage of North American freshwater fish. We find the evolution of sexual dichromatism is coupled to habitat use in darter species. Comparative analyses reveal that mid-water darter lineages exhibit a narrow distribution of dichromatism trait space surrounding a low optimum, suggesting a constraint imposed on the evolution of dichromatism, potentially through predator-mediated selection. Alternatively, the transition to benthic habitats coincides with greater variability in the levels of dichromatism that surround a higher optimum, likely due to relaxation of the predator-mediated selection and heterogeneous microhabitat dependent selection regimes. These results suggest a complex interaction of sexual selection with potentially two mechanisms of natural selection, predation and sensory drive, that influence the evolution of diverse male nuptial coloration in darters.

Quantifying spatial genetic structure can reveal the relative influences of contemporary and historic factors underlying localized and regional patterns of genetic diversity and gene flow – important considerations for the development of effective conservation efforts. Using 10 polymorphic microsatellite loci, we characterize genetic variation among populations across the range of the Eastern Sand Darter (Ammocrypta pellucida), a small riverine percid that is highly dependent on sandy substrate microhabitats. We tested for fine scale, regional, and historic patterns of genetic structure. As expected, significant differentiation was detected among rivers within drainages and among drainages. At finer scales, an unexpected lack of within-river genetic structure among fragmented sandy microhabitats suggests that stratified dispersal resulting from unstable sand bar habitat degradation (natural and anthropogenic) may preclude substantial genetic differentiation within rivers. Among-drainage genetic structure indicates that postglacial (14 kya) drainage connectivity continues to influence contemporary genetic structure among Eastern Sand Darter populations in southern Ontario. These results provide an unexpected contrast to other benthic riverine fish in the Great Lakes drainage and suggest that habitat-specific fishes, such as the Eastern Sand Darter, can evolve dispersal strategies that overcome fragmented and temporally unstable habitats.

Understanding linkages among fluvial geomorphology, habitat, and aquatic biota is critical for effective stream ecosystem conservation. However, composite effects of hydrogeomorphic adjustment and condition, which collectively represent channel stability, on freshwater mussel and stream fish assemblages remain unresolved. Associations between stream hydrogeomorphic characteristics (channel geometry, substrate composition, stream flow) and mussel and stream fish assemblages were explored at 20 study reaches characterized by riffle–pool interfaces (RPIs) in Ohio, USA. At a coarse resolution using categorical classifications of equilibrium (i.e. stable) vs. adjusting (i.e. unstable) RPIs, overall fish and darter density was greater at adjusting RPIs (P = 0.048 and P = 0.024, respectively). Conversely, fish species richness was 1.2× greater at equilibrium than adjusting RPIs (P = 0.047). Analysis of quantitative hydrogeomorphic data collected with fine-resolution surveys showed that hydrogeomorphic parameters explained from 20% (darter assemblage evenness) to 55% (density of mussels known to use darters as hosts) of the variation observed in all assemblages. Drainage area was significant in most models with variable influence: R2 = 0.10 for darter species richness to R2 = 0.41 for Simpson's diversity index of mussels with darter hosts. Other important predictor variables included embeddedness, velocity, shear stress, roughness, channel dimensions, and sediment size. Whereas coarse-level fluvial geomorphic classifications may be meaningful for fish, they appear less so for mussels. Fine-resolution quantitative hydrogeomorphic variables provided substantially more information for both assemblages, although hydrogeomorphology–fish and hydrogeomorphology–mussel relationships were not consistent. Some of the strongest relationships related to mussels that use darters as hosts, suggesting that these species are particularly sensitive to hydrogeomorphic conditions. Collectively, these results indicate that fluvial geomorphic condition and characteristics can simultaneously influence co-dependent stream biota. Stream conservation and management plans that include explicit hydrogeomorphic surveys may appreciably benefit cohabitating freshwater fish and mussel assemblages. Copyright © 2014 John Wiley & Sons, Ltd.

Percina brucethompsoni, the Ouachita Darter, is described as a new species endemic to the Ouachita River system in the Ouachita Highlands of Arkansas. Bruce Thompson first noted the distinctiveness of the new species from the nominal P. nasuta distributed in the White River and Arkansas River basins in his 1977 doctoral dissertation. The new species is delimited through morphological comparisons with P. nasuta and a phylogenetic analysis of the Percina subclade Swainia using two mitochondrial genes. More than 385 specimens were examined for the morphological comparisons, and 54 specimens were sampled for mitochondrial DNA sequencing. Percina brucethompsoni is distinguished from P. nasuta by a shorter snout, a broader and deeper head, six versus seven branchiostegal rays and specific patterns of lateral pigmentation on the side of the body. Phylogenetic analysis of DNA sequences sampled from two regions of the mitochondrial genome indicate that P. brucethompsoni is the sister species of P. nasuta populations in the White River drainage. Neither P. nasuta nor P. phoxocephala are monophyletic in the mitochondrial DNA gene tree. Specimens of P. phoxocephala from the Red River drainage are resolved as the sister lineage of a clade containing all other sampled populations of P. phoxocephala, P. brucethompsoni and P. nasuta. Percina nasuta and P. phoxocephala sampled from the Arkansas River drainage form a clade that is the sister lineage of a clade containing P. brucethompsoni and P. nasuta from the White River drainage.

The dispersal ecology of most stream fishes is poorly characterised, complicating conservation efforts for these species. We used microsatellite DNA marker data to characterise dispersal patterns and effective population size (Ne) for a population of Roanoke logperch Percina rex, an endangered darter (Percidae). Juveniles and candidate parents were sampled for 2 years at sites throughout the Roanoke River watershed. Dispersal was inferred via genetic assignment tests (ATs), pedigree reconstruction (PR) and estimation of lifetime dispersal distance under a genetic isolation-by-distance model. Estimates of Ne varied from 105 to 1218 individuals, depending on the estimation method. Based on PR, polygamy was frequent in parents of both sexes, with individuals spawning with an average of 2.4 mates. The sample contained 61 half-sibling pairs, but only one parent–offspring pair and no full-sib pairs, which limited our ability to discriminate natal dispersal of juveniles from breeding dispersal of their parents between spawning events. Nonetheless, all methods indicated extensive dispersal. The AT indicated unrestricted dispersal among sites ≤15 km apart, while siblings inferred by the PR were captured an average of 14 km and up to 55 km apart. Model-based estimates of median lifetime dispersal distance (6–24 km, depending on assumptions) bracketed AT and PR estimates, indicating that widely dispersed individuals do, on average, contribute to gene flow. Extensive dispersal of P. rex suggests that darters and other small benthic stream fishes may be unexpectedly mobile. Monitoring and management activities for such populations should encompass entire watersheds to fully capture population dynamics.