Clinostomus Elongatus Research Articles

Effects of acute hypoxia exposure and acclimation on the thermal tolerance of an imperiled Canadian minnow.

Elevated water temperatures and low dissolved oxygen (hypoxia) are pervasive stressors in aquatic systems that can be exacerbated by climate change and anthropogenic activities, and there is growing interest in their interactive effects. To explore this interaction, we quantified the effects of acute and long-term hypoxia exposure on the critical thermal maximum (CTmax) of Redside Dace (Clinostomus elongatus), a small-bodied freshwater minnow with sparse populations in the Great Lakes Basin of Canada and designated as Endangered under Canada's Species at Risk Act. Fish were held at 18°C and acclimated to four levels of dissolved oxygen (>90%, 60%, 40%, and 20% air saturation). CTmax was measured after 2 and 10 weeks of acclimation and after 3.5 weeks of reoxygenation, and agitation behavior was quantified during CTmax trials. Aquatic surface respiration behavior was also quantified at 14 weeks of acclimation to oxygen treatments. Acute hypoxia exposure decreased CTmax in fish acclimated to normoxia (>90% air saturation), but acclimation to hypoxia reduced this effect. There was no effect of acclimation oxygen level on CTmax when measured in normoxia, and there was no effect of exposure time to hypoxia on CTmax. Residual effects of hypoxia acclimation on CTmax were not seen after reoxygenation. Agitation behavior varied greatly among individuals and was not affected by oxygen conditions. Fish performed aquatic surface respiration with low frequency, but performed it earlier when acclimated to higher levels of oxygen. Overall, this work sheds light on the vulnerability of fish experiencing acute hypoxia and heat waves concurrently.

Effect of enrichment on gamete production, gamete quality, and spawning coloration in hormonally induced redside dace Clinostomus elongatus

Due to the alarming rates of freshwater fish extinctions, urgent action is needed to develop captive breeding programs for imperiled species and enhance existing practices to improve reproductive outcomes. Here, we investigated the effects of enrichment on gamete production, quality, and spawning coloration following hormone injection (i.e. carp pituitary, gonadotropin) in the endangered redside dace Clinostomus elongatus, a sexually dimorphic, presumably obligate nest parasite. C. elongatus were reared in either a non-enriched environment (i.e. barren) or an enriched environment (i.e. substrate, plants, and spawning nest-building hosts) for 1 yr prior to hormone induction. We found no differences in the proportion of free-flowing gamete expression between male and female C. elongatus in the non-enriched and enriched environments. However, males reared in enriched environments had higher sperm motility, while among females, there was no significant difference in egg diameter. Furthermore, enrichment was found to influence spawning coloration, with males and females reared in enriched environments displaying redder hues compared to those reared in non-enriched environments prior to hormone induction. However, post hormone injection, no significant differences in red coloration were observed between non-enriched and enriched males and females, indicating that hormone induction improved coloration in non-enriched fish. This study highlights the effect of enrichment on gamete production, quality, and spawning coloration and provides information for captive breeding C. elongatus. These findings provide valuable insights into the potential of enrichment and induction techniques to enhance reproductive outcomes when captively breeding endangered species of fishes.

Transport does not influence maximum metabolic rate or thermal tolerance of endangered redside dace (Clinostomus elongatus)

Reintroduction is an important tool in the conservation and recovery of aquatic species at risk. However, components of the reintroduction process such as transportation have the potential to induce physiological stress and the extent to which preparatory techniques can mitigate this stress is poorly understood in small-bodied fishes. To address this concern, we studied the effect of transport on two fitness-related performance measures: maximum metabolic rate and thermal tolerance in redside dace ( Clinostomus elongatus), an imperilled small-bodied stream fish native to eastern North America. Prior to transportation, we manipulated the body condition of redside dace over a 12-week period, by providing either low (1% of their total body mass) or high (2% of their total body mass) rations. The goal of this manipulation was to influence body condition, as higher body condition can enhance physiological performance. Subsequently, redside dace were transported for varying durations: 0, 3, and 6 h. Following transportation, we measured maximum metabolic rate (µmol/h) and thermal tolerance (CTmax, °C). Our results indicate that neither transport nor body condition had a significant effect on maximum metabolic rate or thermal tolerance (CTmax). These findings provide preliminary evidence that redside dace can physiologically tolerate transport based on the endpoints measured and this information may possibly be extended to other small-bodied fish, for which information is lacking.

Reproductive phenology and behaviour of endangered redside dace (Clinostomus elongatus) in urban streams.

Investigation of the reproductive phenology and spawning behaviour of imperilled species in relation to environmental variability is needed to understand a critical component of species life history. In this study, we used redside dace (Clinostomus elongatus), a freshwater leuciscid listed as Endangered under Canada's Species at Risk Act, to model spawning phenology and make predictions about spawning initiation using historical and climate change projected thermal cues (measured as cumulative growing degree days), and provide an ethological description of spawning behaviour. Logistic regression models applied to 4 years of average daily stream water temperature data and field behavioural observations of the onset of spawning activity indicated a 50% probability of spawning initiation when cumulative growing degree days reached 214°C days and a 95% probability of spawning initiation at 288°C days. Using two climate change scenarios (i.e., a mid-century 1.6°C increase and an end of century 3.6°C increase), spawning initiation was predicted to advance 3 days by the year 2050 and 7 days by the year 2100. Underwater video cameras placed at two sites within an urban stream captured 73 unique spawning events revealing that redside dace spawn in pairs as well as in dense, tightly packed groups (more than 20 individuals). Moreover, there is evidence of redside dace having a polygynandrous mating system, as female redside dace spawned with multiple males in 45.2% of the total spawning events recorded. Taken together, this study provides important insights into redside dace spawning initiation and behaviour, key life-history traits having conservation implications for future reproductive success and, ultimately, population dynamics.

Acute thermal stress elicits interactions between gene expression and alternative splicing in a fish of conservation concern.

Transcriptomic research provides a mechanistic understanding of an organism's response to environmental challenges such as increasing temperatures, which can provide key insights into the threats posed by thermal challenges associated with urbanization and climate change. Differential gene expression and alternative splicing are two elements of the transcriptomic stress response that may work in tandem, but relatively few studies have investigated these interactions in fishes of conservation concern. We studied the imperilled redside dace (Clinostomus elongatus) as thermal stress is hypothesized to be an important cause of population declines. We tested the hypothesis that gene expression-splicing interactions contribute to the thermal stress response. Wild fish exposed to acute thermal stress were compared with both handling controls and fish sampled directly from a river. Liver tissue was sampled to study the transcriptomic stress response. With a gene set enrichment analysis, we found that thermally stressed fish showed a transcriptional response related to transcription regulation and responses to unfolded proteins, and alternatively spliced genes related to gene expression regulation and metabolism. One splicing factor, prpf38b, was upregulated in the thermally stressed group compared with the other treatments. This splicing factor may have a role in the Jun/AP-1 cellular stress response, a pathway with wide-ranging and context-dependent effects. Given large gene interaction networks and the context-dependent nature of transcriptional responses, our results highlight the importance of understanding interactions between gene expression and splicing for understanding transcriptomic responses to thermal stress. Our results also reveal transcriptional pathways that can inform conservation breeding, translocation and reintroduction programs for redside dace and other imperilled species by identifying appropriate source populations.

Choosing source populations for conservation reintroductions: lessons from variation in thermal tolerance among populations of the imperilled redside dace1

Reintroduction is an increasingly common conservation tool used to recover populations of imperilled species, but its success depends on the suitability of the introduced animals’ phenotype for their new habitat. For fishes, thermal tolerance may be a key trait in urbanized habitats. We compared thermal tolerance (CTmax) among three lineages (western, central, eastern) of imperilled redside dace (Clinostomus elongatus). CTmax of eastern adults was 3–4 °C lower than that of the other lineages, but adults of each lineage had similar thermal acclimation responses. In contrast, the acclimation response of juveniles differed by ∼80% between the central and western lineages. Using these data, we predicted how each lineage would fare in a hypothetical reintroduction to relatively warm urbanized habitats. Owing to the differences in juvenile acclimation responses, predicted thermal safety margins for the central lineage were double those predicted for the western lineage. Overall, we suggest that CTmax is a useful trait to incorporate into the source population selection process; however, there is an urgent need for the establishment of captive experimental research populations of imperilled species to address remaining uncertainties.

Autumn electrofishing reduces harm to Ontario (Canada) stream fishes collected during watershed health monitoring

Electrofishing surveys provide important information on watershed health, and the status of imperiled and recreationally important stream fishes. Concerns about the harmful effects of electrofishing on the endangered redside dace Clinostomus elongatus have resulted in restrictions on its use in sampling activities in the province of Ontario, Canada. However, the effectiveness of these restrictions is unproven. We undertook a paired sampling gear study in 2018-2019 to test whether an alternate gear (seine nets) or a change in electrofishing timing (autumn rather than summer) reduced harm to stream fishes. The study took place in streams located in the Greater Toronto Area. We found large differences in the frequency and magnitude of sampling-related mortalities between sampling gear and seasons. During individual surveys, electrofishing mortality never exceeded 9% in the summer or 4% in the autumn, while seining-related mortality reached 60% at two stream sites. Overall, autumn electrofishing resulted in mortality rates that were 5.6 and 15 times lower than summer electrofishing and summer seining. These results indicate that survival of Ontario stream fishes can be improved by delaying electrofishing until early autumn.

Using occupancy models to assess the effectiveness of underwater cameras to detect rare stream fishes

Abstract Many conservation efforts for freshwater fishes have been undertaken; however, continuing the monitoring of both the distribution and the abundance of species to determine the effectiveness of these actions can be difficult. As species increase in rarity, they are more difficult to detect in the field, making inferences on occupancy less reliable. Conventional sampling methods, such as electrofishing and seining, require the physical handling of rare fishes, which may cause stress and mortality and, consequently, compromise conservation goals and limit monitoring programmes. Non‐invasive surveillance methods, including underwater video, are playing an increasingly important role. In this study, occupancy models were used to estimate the detection probability of underwater cameras as an alternative to the conventional sampling methods for rare stream fishes. Redside dace (Clinostomus elongatus), a small minnow listed as Endangered, was used as a model organism for rarity. A total of 69 historical redside dace sites were sampled using three sampling methods to determine the effect of gear type on detecting and identifying the habitat preferences of this rare minnow. On average, using multiple underwater cameras is as effective at detecting a rare minnow as conventional sampling methods (backpack electrofisher and seine) and causes no harm. The detection probability of both underwater cameras and backpack electrofishing were adversely affected by turbidity, whereas seining was positively affected by stream velocity. The probability of occupancy of redside dace is driven by open channels and sediment size, and this provides a strong basis for informing stream restoration projects. The use of multiple underwater cameras over conventional sampling methods is recommended when sampling for rare and endangered minnows in systems with low turbidity.

Thermal tolerance depends on season, age and body condition in imperilled redside dace Clinostomus elongatus.

Urbanization tends to increase water temperatures in streams and rivers and is hypothesized to be contributing to declines of many freshwater fishes. However, factors that influence individual variation in thermal tolerance, and how these may change seasonally, are not well understood. To address this knowledge gap, we studied redside dace Clinostomus elongatus, an imperilled stream fish native to rapidly urbanizing areas of eastern North America. In wild redside dace from rural Ohio, USA, acute upper thermal tolerance (i.e. critical thermal maximum, CTmax) ranged between ~34°C in summer (stream temperature ~22°C) and 27°C in winter (stream temperature ~2°C). Juveniles had higher CTmax than adults in spring and summer, but in winter, CTmax was higher in adults. Thermal safety margins (CTmax - ambient water temperature; ~11°C) were less than the increases in peak water temperature predicted for many redside dace streams due to the combined effects of climate change and urbanization. Furthermore, behavioural agitation occurred 5-6°C below CTmax. Safety margins were larger (>20°C) in autumn and winter. In addition, redside dace were more sensitive (2.5°C lower CTmax) than southern redbelly dace Chrosomus erythrogaster, a non-imperilled sympatric cyprinid. Body condition (Fulton's K) of adult redside dace was positively correlated with CTmax, but in juveniles, this relationship was significant only in one of two summers of experiments. Next, we measured CTmax of captive redside dace fed experimentally manipulated diets. In adults, but not juveniles, CTmax was higher in fish fed a high- vs. low-ration diet, indicating a causal link between nutrition and thermal tolerance. We conclude that redside dace will be challenged by predicted future summer temperatures, especially in urbanized habitats. Thus, habitat restoration that mitigates temperature increases is likely to benefit redside dace. We also suggest habitat restoration that improves food availability may increase thermal tolerance, and thus population resilience.

Seasonal variation in thermal tolerance of redside dace Clinostomus elongatus

Organisms living in environments with oscillating temperatures may rely on plastic traits to sustain thermal tolerance during high temperature periods. Phenotypic plasticity in critical thermal maximum (CTmax) is a powerful thermoregulative strategy that enables organisms to adjust CTmax when ambient temperatures do not match thermal preference. Given that global temperatures are increasing at an unprecedented rate, identifying factors that affect the plastic response in CTmax can help predict how organisms are likely to respond to changes in their thermal landscape. Using an experimental thermal chamber in the field, we investigated the effect of short-term acclimation on the CTmax and thermal safety margin (TSM) of wild-caught redside dace, Clinostomus elongatus, (n= 197) in a northern population in Two Tree River, Ontario. Streamside CTmax trials were used to identify the maximum temperature at which redside dace maintain equilibrium, providing a powerful tool for understanding how thermal stress affects individual performance. CTmax and TSM of redside dace were sensitive to changes in temperature, regardless of season, suggesting that temperature pulses caused by climate change or urban activities can impose negative fitness consequences year round. Interestingly, an individual's recent thermal history was more influential to its thermal tolerance than the current ambient water temperature. While the CTmax of redside dace increased with body size, the effect of body size on TSM remains unclear based on our models. The results provide insight into the thermal performance of redside dace that, to date, has been difficult to assess due to the species' rarity and lack of suitable streamside protocols.

Life History Traits and Status of a Peripheral Redside Dace (Clinostomus elongatus) Population in Minnesota

Abstract Redside dace Clinostomus elongatus in Minnesota represent genetically unique peripheral populations on the extreme western edge of their native range with uncertain population status. Electrofishing surveys were conducted in 2017 in the Little Cannon River watershed to ascertain life history traits (e.g., age, growth, reproductive traits) for comparison to core populations in eastern North America and to assess population status. Minnesota redside dace grew faster but lived shorter lives than their core populations/counterparts. Females matured at age-2 and about 80 mm total length and males at age-1 and 70 mm. Females produced up to 962 eggs. Estimated population size for age 1+ dace was 9251 (95% C.I. 8300–10,201) and for age 2+ was 6600 (95% C.I. 5789–7411). These values exceeded a demographic minimum viable population estimate of 3305 (nearly double) suggesting that redside dace should persist in this watershed for at least the next two decades (until ≈ 2040).

Pocket wetlands as additions to stormwater treatment train systems: a case study from a restored stream in Brampton, ON, Canada

Ontario urban development necessitates stream restoration projects for existing watercourses that flow through a property under development. This is part of the planning process, mandated by local conservation authorities to conserve the natural heritage and ecological function of natural areas identified under Ontario’s Ecological Land Classification. Stream restoration is commonly incorporated into larger stormwater management upgrades in the re-developed landscape. This study evaluates flow attenuation and water quality mitigation of a pocket wetland (PW), a shallow constructed wetland located at the outlet of a stormwater management system, within a major channel realignment and stream restoration project in Brampton, Ontario, Canada. The PW was incorporated into the floodplain of the natural channel design, between the outflow of the stormwater pond and a tributary of Churchville Creek. The latter contains habitat for redside dace (Clinostomus elongates), a designated species-at-risk under the Ontario Endangered Species Act. The addition of the PW to the stormwater treatment train was designed to mitigate the impacts that poor water quality has on local biota. Runoff, water temperature, total suspended solids and conductivity were monitored during 21 rainfall events between May and October 2014. Average PW event residence time was ~2 h and the overall changes in water quality between instream monitoring sites were negligible. Instream water temperature changes were minor (< 1°C) during flow events, with small increases in water temperature (< 0.5°C) observed during baseflow. The change in suspended sediment between the stream and PW flow was −22–31 mg/L. Suspended sediment inputs were greatest in the fall, which coincides with larger rainfall events. This study demonstrates PWs provide additional water storage time, and have added value in stormwater management. Although PWs are not formally included in current policy requirements, evidence from this study suggests the inclusion of PWs in future projects is worthwhile.

Conservation genetics of redside dace (Clinostomus elongatus): phylogeography and contemporary spatial structure

Redside dace Clinostomus elongatus (Teleostei: Cyprinidae) is a species of conservation concern that is declining throughout its range as a result of habitat fragmentation, degradation and loss. We characterized the genetic structure and diversity of redside dace populations across the species range using mitochondrial and microsatellite data to inform conservation efforts and assess how historical and recent events have shaped genetic structure and diversity within and among populations. Phylogeographic structure among 28 redside dace populations throughout southern Ontario (Canada) and the United States was assessed by sequence analysis of the mitochondrial cytochrome b and ATPase 6 and 8 genes. Populations were also genotyped using ten microsatellite loci to examine genetic diversity within and among populations as well as contemporary spatial structuring. Mitochondrial DNA sequence data revealed three geographically distinct lineages, which were highly concordant with groupings identified by microsatellite analysis. The combined genetic data refute published glacial refugia hypotheses of a single Mississippian refugium or of two lineages associated with Mississippian and Atlantic refugia. Secondary contact between the two eastern groups was documented in the Allegheny River drainage and tributaries to Lake Ontario. With the exception of several allopatric populations within the Allegheny watershed, high genetic structuring among populations suggests their isolation, indicating that recovery efforts should be population-based.

Establishing detection thresholds for environmental DNA using receiver operator characteristic (ROC) curves

Environmental DNA (eDNA) detection is increasingly being used to assess the potential presence of aquatic species. Setting defensible thresholds for qPCR assays are necessary to differentiate “detection” from “non-detection”, but threshold rationales are rarely reported in eDNA studies. Detection thresholds for data inclusion and exclusion have implications for downstream data analysis; uncritical acceptance could result in false positive results (Type I error), whereas overly conservative thresholds could result in high false negative interpretation (Type II error). We assessed the use of the receiver operator characteristics (ROC) framework to identify a detection threshold for balancing sensitivity and specificity of eDNA data. The ROC framework was tested using empirical eDNA data from redside dace (Clinostomus elongatus), an endangered freshwater fish in southwestern Ontario. Based on negative controls, positive controls, and quality assurance guidelines, a minimum concentration of 1 copy reaction−1 was identified as the most appropriate threshold for this study. Although optimal thresholds will likely vary between studies and labs based on empirical data, the ROC framework provides a statistical method for establishing defensible thresholds for data acceptance or rejection as well as tradeoffs between the sensitivity and specificity of eDNA data.

Physiological functions of osmolality and calcium ions on the initiation of sperm motility and swimming performance in redside dace, Clinostomus elongatus

Reproductive potential of fish stocks is critically dependent on sperm performance in an aquatic environment. The aim of this study is to test hypotheses, which govern the initiation of sperm motility and swimming performance, through physiological functions of osmolality and Ca2+ ion, in a threatened species of freshwater fish, the redside dace, Clinostomus elongatus. Spermatozoa motility was activated in either ionic or non-ionic media spanning a range of osmolalities. The role of Ca2+ channels on induction of spermatozoa motility and velocity was experimentally investigated by diluting sperm in media that contain various Ca2+ channel blockers. Results show that initiation of spermatozoa motility is a hypo-osmolality dependent mechanism. Inhibitors for L-type Ca2+ channels partially prohibited initiation of spermatozoa motility, while velocity was significantly reduced in both L-type and T-type Ca2+ channel blockers. Examination using W-7, an inhibitor for Ca2+-dependent calmodulin, showed significant decreases in spermatozoa motility and velocity. Involvement for Ca2+ in axonemal beating was confirmed by significant increases in velocity after adding Ca2+ into the activation media, while motility remained unchanged in Ca2+ supplemented activation media. Together, these findings suggest the involvement of Ca2+ in hypo-osmolality-dependent initiation of spermatozoa motility mediated by activation of Ca2+ binding protein in the axoneme of a freshwater fish sperm. Blocking Ca2+ exchange through L- or T-type Ca2+ channel influences flagellar beating force and leads to decrease in spermatozoa velocity.

Development of a Sperm Cryopreservation Protocol for Redside Dace: Implications for Genome Resource Banking

AbstractPopulations of Redside Dace Clinostomus elongatus have declined in many areas across the species’ North American range. Therefore, the development of sperm cryopreservation technology would provide an invaluable means of preserving genetic diversity in populations that are in imminent danger of extirpation. We developed cryopreservation protocols by testing the effects of diluent (buffered sperm motility‐inhibiting saline solution [BSMIS]; BSMIS + glycine; sucrose; and Hanks’ balanced salt solution [HBSS]), cryoprotectant (dimethyl sulfoxide [DMSO]; propylene glycol [PG]; N,N‐dimethylacetamide [DMA]; and methanol), freezing rate (1, 5, and 10°C/min), and male‐to‐male variation on sperm quality. Incubating sperm in extenders affected motility; BSMIS + glycine + methanol, BSMIS + glycine + PG, and HBSS + methanol were the only treatments for which motility was not significantly different from that of fresh sperm. Sperm frozen with sucrose had higher motility than sperm frozen with BSMIS + glycine, and sperm frozen with DMSO had higher motility than sperm frozen with methanol. Freezing rates were evaluated for BSMIS + glycine, HBSS, and sucrose; all diluents were frozen with DMSO. The effect of freezing rate was not significant for BSMIS + glycine or for HBSS, but an effect was detected for sucrose, with sperm frozen at 5°C/min or 10°C/min having higher motility than sperm frozen at 1°C/min. The effect of extender was not significant at 1°C/min or 5°C/min, but an effect was detected at 10°C/min such that sperm frozen with sucrose had the highest motility. Male‐to‐male variability was evaluated by using sucrose + DMSO and a freezing rate of 10°C/min. For these males, the sperm motility recovery index ranged from 6.67% to 79.27%, and the sperm velocity recovery index ranged from 21.37% to 57.33%. Our findings demonstrate that cryopreservation of Redside Dace sperm in a sucrose + DMSO extender at a freezing rate of 10°C/min is adequate for preserving genetic diversity via sperm banks.

Spawning coloration, female choice and sperm competition in the redside dace, Clinostomus elongatus

Understanding pre- and postcopulatory mechanisms of sexual selection (male–male competition and female choice) can provide insight into the evolution of male ornamentation. In this study, we use an integrative approach to study sexual selection by incorporating measures of both mechanisms using the redside dace, Clinostomus elongatus, a freshwater, externally fertilizing fish found in streams of eastern North America. We measured the success of individual male redside dace in both pre- and postspawning sexual selection and related the success of males to a range of traits, including spectral properties and the size of their red spawning coloration, body size metrics and sperm quality. We found significant sexual dimorphism in the relative amount and spectral properties (saturation and brightness) of the red spawning coloration, with males being more ornamented than females. Using dichotomous mate choice trials, we found that females did not favour males with relatively larger red spawning coloration area and more saturated or brighter red spawning coloration. Males with relatively more red spawning area would be favoured in male–male postspawning sperm competition because they possess sperm with higher velocity, and sperm velocity was determined to be the key predictor of sperm competition success as assessed by paternity analyses related to in vitro sperm competition trials. These results suggest that prespawning selection via female choice is not driving the evolution of red spawning coloration and that postspawning selection via male–male competition is primarily determined by sperm velocity, which was correlated with the relative amount of red spawning coloration.

Estimating local and regional population sizes for an endangered minnow, redside dace (Clinostomus elongatus), in Canada

ABSTRACTThe Laurentian Great Lakes have undergone drastic declines in freshwater fishes, with 22 species having become extinct in the past century and many more currently at risk. One such species is the endangered minnow, the redside dace (Clinostomus elongatus), which is undergoing severe declines across its entire range.Depletion and mark–recapture surveys were used to quantify population estimates of redside dace at several spatial scales (pool, reach and catchment) across several Great Lakes tributaries in Canada.There was large variation in the local population estimates and the rate of occurrence of redside dace populations. In some cases, such as Gully Creek, a Lake Huron tributary, redside dace were widespread (9/10 of pools) but in low abundances (13.5 individuals per pool ± 5.09 ). In other cases, such as in the Don River, redside dace were highly localized (2/27 pools) but in relatively high abundance (99.2 individuals/pool ± 18.1).Extrapolated population estimates at the catchment scale showed that three of the five study populations were below conservative estimates needed for long‐term population viability.Differences in redside dace populations were driven by adjacent land‐use. Post‐hoc analyses revealed strong negative associations between population estimates and impervious land‐use (i.e. urbanization) at both the pool and sub‐catchment level.Immediate recovery actions that will focus on eliminating chronic and episodic impacts of adjacent land‐use and improve connectivity are needed to help ensure redside dace, like many freshwater species in the Laurentian Great Lakes, remain a species at risk of – rather than facing – extinction.Copyright © 2012 John Wiley &amp; Sons, Ltd.

Impact of species-specific dispersal and regional stochasticity on estimates of population viability in stream metapopulations

Species dispersal is a central component of metapopulation models. Spatially realistic metapopulation models, such as stochastic patch-occupancy models (SPOMs), quantify species dispersal using estimates of colonization potential based on inter-patch distance (distance decay model). In this study we compare the parameterization of SPOMs with dispersal and patch dynamics quantified directly from empirical data. For this purpose we monitored two metapopulations of an endangered minnow, redside dace (Clinostomus elongatus), using mark-recapture techniques across 43 patches, re-sampled across a 1 year period. More than 2,000 fish were marked with visible implant elastomer tags coded for patch location and dispersal and patch dynamics were monitored. We found that species-specific dispersal and distance decay models provided qualitatively similar rankings of viable patches; however, there were differences of several orders of magnitude in the estimated intrinsic mean times to extinction, from 24 and 148 years to 362 and >100,000 years, depending on the population. We also found that the rate of regional stochasicity had a dramatic impact for the estimate of species viability, and in one case altered the trajectory of our metapopulation from viable to non-viable. The divergent estimates in time to extinction times were likely due to a combination species-specific behavior, the dendritic nature of stream metapopulations, and the rate of regional stochasticity. We demonstrate the importance of developing comparative analyses using species- and patch-specific data when determining quantitative estimates for mean time to extinction, which in the case of redside dace, were highly sensitive to different estimates of dispersal.

Isolation and characterization of microsatellite loci in the redside dace, Clinostomus elongatus

We isolated and characterized eight polymorphic microsatellite loci for redside dace (Clinostomus elongatus), a colorful North American cyprinid that is threatened or endangered throughout most of its range. The number of alleles per locus ranged from three to eighteen, with observed heterozygosity ranging from 0.31–0.92. Cross-amplification revealed that these markers will also be useful for examining closely related and more distantly related species, including the rosyside dace (Clinostomus funduloides), Lahontan redside shiner (Richardsonius egregius), hornyhead chub (Nocomis biguttatus), and central stoneroller (Campostoma anomalum). These microsatellite loci will provide a valuable set of tools for examining fine and coarse scale population structure, exploring reproductive success, and testing outcomes of proposed conservation initiatives (e.g. captive breeding and translocation of wild individuals) for redside dace.