Session A7- Research

Improperly designed road crossings act as barriers to movement of aquatic organisms and can depress local abundance and reduce local species richness, with potential impacts on population viability and biotic diversity. However, because abundance and richness are highly spatially and temporally heterogeneous and the relative importance of immigration on demography is uncertain, population and community-level effects can be difficult to detect. In this study we tested the effects of barriers to upstream movements on the local abundance and species richness of a diverse assemblage of resident stream fishes in the Monongahela National Forest, West Virginia, USA. Fishes were sampled using simple standard techniques above- and below- road crossings that were either likely or unlikely to be barriers to upstream fish movements (based on physical dimensions of the crossing). We predicted that abundance of resident fishes would be lower in the upstream sections of streams with predicted impassable barriers, that the strength of the effect would vary among species, and that these variable effects on abundance would translate into lower species richness. Supporting these predictions, stream sections located above predicted impassable culverts had fewer than half the number of species and less than half the total fish abundance, while stream sections above and below passable culverts had essentially equivalent richness and abundance. Our results are consistent with the importance of immigration and population connectivity to local abundance and species richness of stream fishes. In tum, these results suggest that when measured at appropriate scales (multiple streams within watersheds), with simple protocols amenable to use by management agencies, differences in local abundance and species richness may serve as indicators of the extent to which road crossings are barriers to fish movement, and help determine whether road crossing improvements have restored connectivity to stream fish populations and communities

Dysregulation of CXC motif ligand 10 during aging and association with cognitive performance

Chronic low-grade inflammation during aging (inflammaging) is associated with cognitive decline and neurodegeneration, however, the mechanisms underlying inflammaging are unclear. We studied a population (n = 361) of healthy young and old adults from the MyoAge cohort. Peripheral levels of C-X-C motif chemokine 10 (CXCL10) was found to be higher in older adults, compared with young, and negatively associated with working memory performance. This coincided with an age-related reduction in blood DNA methylation at specific CpGs within the CXCL10 gene promoter. In vitro analysis supported the role of DNA methylation in regulating CXCL10 transcription. A polymorphism (rs56061981) that altered methylation at one of these CpG sites further associated with working memory performance in two independent aging cohorts. Studying prefrontal cortex samples, we found higher CXCL10 protein levels in those with Alzheimer’s disease, compared to aged controls. These findings support the association of peripheral inflammation, as demonstrated by CXCL10, in aging and cognitive decline. We reveal age-related epigenetic and genetic factors which contribute to the dysregulation of CXCL10

Evaluation of Six Strains of Rainbow Trout (Salmo gairdneri) Stocked as Fingerlings in Porcupine Reservoir, Utah

Different strains of rainbow trout (Salmo gairdneri), Ten Sleep, Sand Creek, Beitey, Shepherd-of-the-Hills, New Zealand, Fish Lake- Desmet, Desmet, were compared for survival to the creel, growth and catchability after being stocked in a fluctuating 80 ha Utah reservoir . Fish were stocked in the spring and fall as fingerlings and monitored by creel censusing, gill netting and electrofishing. Fish were tagged with coded wire snout tags prior to stocking . An angler opinion survey was conducted to determine angler satisfaction with numbers and size of fish caught. Regardless of strain, spring stocking was superior to fall stocking in survival to the creel. In the spring 78 stocking the Ten Sleep strain had the highest survival to the creel (33.7 percent), followed in order by Shepherd-of-the-Hills (11.0 percent), Beitey (5.5 percent), Sand Creek (5.4 percent), New Zealand (4.1 percent), and Fish Lake-Desmet (2 .9 percent). In the spring 79 stocking the Shepherd-of-the- Hills strain had the highest survival to the creel (7 .6 percent), followed in order by the Sand Creek (7.3 percent) and the Ten Sleep (6.5 percent). Similar trends in survival were found in gill netting and electrofishing samples. Migration out of the reservoir was negligible for each strain. There were no strain differences in catchability by different methods (shore, boat) or gear (bait, artificial lure). Differences in growth between the fastest growing strains (Ten Sleep, Sand Creek) and the slowest growing strains (New Zealand, Fish Lake-Desmet) averaged as great as 16 mm in length and 43 g in weight. Differences in growth and survival among strains were great enough to span the range of angler satisfaction with numbers caught and size of fish caught from satisfactory to unsatisfactory. Therefore, strain selection can be a useful tool to improve fingerling stocking programs and manipulate the number of anglers who are satisfied with the angling experience

Data from: Experimental test of genetic rescue in isolated populations of brook trout

Genetic rescue is an increasingly considered conservation measure to address genetic erosion associated with habitat loss and fragmentation. The resulting gene flow from facilitating migration may improve fitness and adaptive potential, but is not without risks (e.g., outbreeding depression). Here, we conducted a test of genetic rescue by translocating ten (five of each sex) brook trout (Salvelinus fontinalis) from a single source to four nearby and isolated stream populations. To control for the demographic contribution of translocated individuals, ten resident individuals (five of each sex) were removed from each recipient population. Prior to the introduction of translocated individuals, the two smallest above-barrier populations had substantially lower genetic diversity, and all populations had reduced effective number of breeders relative to adjacent below-barrier populations. In the first reproductive bout following translocation, 31 of 40 (78%) translocated individuals reproduced successfully. Translocated individuals contributed to more families than expected under random mating and generally produced larger full-sibling families. We observed relatively high (>20%) introgression in three of the four recipient populations. The translocations increased genetic diversity of recipient populations by 45% in allelic richness and 25% in expected heterozygosity. Additionally, strong evidence of hybrid vigour was observed through significantly larger body sizes of hybrid offspring relative to resident offspring in all recipient populations. Continued monitoring of these populations will test for negative fitness effects beyond the first generation. However, these results provide much-needed experimental data to inform the potential effectiveness of genetic rescue-motivated translocations

Concurrent Sessions A: Passage Effectiveness Monitoring in Small Streams I - Alternatives to Direct Detection for Assessing the Effectiveness of Aquatic Organism Passage

Direct detection of individuals is often considered the most reliable indicator of the effectiveness of aquatic organism passage efforts, but given spatial and temporal variation in movement along with other logistical constraints this detection can be difficult and expensive to obtain, with a high probability of false negatives (concluding no passage when passage is possible). However, the ultimate goal of these projects is to restore population connectivity and increase population resilience. Therefore, we expect that effective aquatic organism passage should be manifest in predictable changes in abundance and genetic structure, which can at the same time serve as indicators of individual movement. Towards this goal we focused on two approaches. First, we used patterns of abundance and diversity above and below road crossings to test whether these patterns could be used to infer passage and connectivity. Second we took advantage of the discrete spawning location strategy used by most stream-dwelling species combined with new tools to assess local genetic structure (via parentage and sibling assignment) to determine whether relatedness structure was consistent with movement and successful dispersal across a potential barrier. For each of these approaches we employed two methods 1) simulation models which define sensitivity, power, and accuracy and 2) field applications which directly test performance. These approaches have been rigorously evaluated in simulations and successfully tested in the field in several locations in the northeastern US and these efforts have helped to define which species, which situations, and which sampling regimes where these techniques will and will not be effective. We are currently working to incorporating these models into assessment frameworks at both site and landscape scales

Data from: Effective number of breeders provides a link between interannual variation in stream flow and individual reproductive contribution in a stream salmonid

The effective number of breeders that give rise to a cohort (Nb) is a promising metric for genetic monitoring of species with overlapping generations; however, more work is needed to understand factors that contribute to variation in this measure in natural populations. We tested hypotheses related to interannual variation in Nb in two long-term studies of brook trout populations. We found no supporting evidence for our initial hypothesis that inline image reflects inline image (defined as the number of adults in a population at the time of reproduction). inline image was stable relative to inline image and did not follow trends in abundance (one stream negative, the other positive). We used stream flow estimates to test the alternative hypothesis that environmental factors constrain Nb. We observed an intermediate optimum autumn stream flow for both inline image (R2 = 0.73, P = 0.02) and full-sibling family evenness (R2 = 0.77, P = 0.01) in one population and a negative correlation between autumn stream flow and full-sib family evenness in the other population (r = −0.95, P = 0.02). Evidence for greater reproductive skew at the lowest and highest autumn flow was consistent with suboptimal conditions at flow extremes. A series of additional tests provided no supporting evidence for a related hypothesis that density-dependent reproductive success was responsible for the lack of relationship between Nb and NC (so-called genetic compensation). This work provides evidence that Nb is a useful metric of population-specific individual reproductive contribution for genetic monitoring across populations and the link we provide between stream flow and Nb could be used to help predict population resilience to environmental change