Vulnerability of Pacific salmon to invasion of northern pike (Esox lucius) in Southcentral Alaska.
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ABSTRACT:
SUBMITTER: Jalbert CS
PROVIDER: S-EPMC8253411 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The microbiome of freshwater fish has important implications for both commercial and recreational fishing because it can have significant impacts on host heath, spoilage rates, and susceptibility to disease. The aqueous environment serves as a possible avenue for continuous introduction of microbes to an animal host, but little is known about how the surrounding microbiota contribute to piscine microbiomes. To better understand the composition of the fish microbiome exposed to the natural environment, we profiled the microbial composition of the gut and the skin mucosal surface (SMS) of northern pike (Esox lucius) and the surrounding river water. We collected fish samples from eight sites along a single river in southwestern Quebec, Canada and analyzed the microbial composition via 16S rRNA sequencing. Our results reveal robust taxonomic differences between the SMS and the gut, indicating a divergence between the microbiomes. The gut community was characterized by a lower alpha diversity compared to the SMS and a large proportion of Cetobacterium, a genus previously linked to carnivorous species. On the other hand, the SMS was more similar to the water than the gut at the family level but divergent at lower taxonomic levels, with fewer than 30% of amplicon sequence variants (ASVs) shared between the SMS and water. In total, our results suggest the establishment of distinct communities across the two fish sites, as well as a clear separation from the microbes in surrounding waters. These data indicate that despite continuous exposure to water, pike are able to establish and maintain unique microbial communities.
| S-EPMC6751255 | biostudies-literature
Project description:The northern pike (Esox lucius L.), an important predatory freshwater species, is undergoing significant population decline. In this study, 18 novel polymorphic microsatellite loci were isolated and used for assessing genetic variation in the Chinese Ulungur and Hungarian Balaton populations of the species. The number of alleles ranged from 2 to 13, observed heterozygosity from 0.154 to 0.920 and expected heterozygosity from 0.145 to 0.921, thereby indicating the specific usefulness of these suites of markers for investigating genetic variability.
| S-EPMC3085365 | biostudies-literature
Project description:Northern pike (Esox lucius) was widely distributed in the high latitudes of the northern hemisphere. In China, northern pike was originally distributed only in the upper reaches of the Irtysh River in Xinjiang and has appeared in many water bodies outside the Irtysh River Basin in Northern Xinjiang. A total of four populations were collected from north to south in Xinjiang, including Irtysh River (RIR), Ulungu Lake (LUL), a small lake nearby Ulungu River (LJD), and Bosten Lake (LBO). We estimated population genomic parameters, performed gene flow analysis, and estimated the effective population size of each population. The proportion of individuals with high inbreeding coefficient (F ≥ 0.0625) accounted for 36.4% (44/121) of all sequenced individuals, approximately 4.5% (1/22) in LUL, 25.9% (7/27) in LBO, 42.9% (18/42) in RIR, and 60% (18/30) in LJD. RIR had the highest mean of genomic relatedness (coancestry coefficient = 0.025 ± 0.040, IBD = 0.036 ± 0.078). Gene flow results showed that the population spreading was from RIR into two branches, one was LBO, and the other continued to split into LUL and LJD, and migration signal from LBO to LUL was detected. Our results suggested that the extinction risk of northern pike was very low in Xinjiang of China, and the controlled capture fishery of northern pike could be developed reasonably.
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Project description:Mercury (Hg) is a toxic environmental contaminant associated with oxidative stress in freshwater fish. A known antagonist to Hg, selenium (Se), may reduce the toxic effects of Hg. In this study, the relation among Se, methylmercury (MeHg), inorganic mercury (IHg), total mercury (THg), and the expression of biomarkers of oxidative stress and metal regulation in livers of northern pike were examined. Livers from northern pike were collected from 12 lakes in Isle Royale National Park, Pictured Rocks National Lakeshore, Sleeping Bear Dunes National Lakeshore, and Voyageurs National Park. The concentrations of MeHg, THg, and Se were measured in liver tissue, and the expression of superoxide dismutase (sod), catalase (cat), glutathione s-transferase (gst), and metallothionein (mt) was assessed. There was a positive relationship between the concentrations of THg and Se, with a Hg:Se molar ratio less than one in all livers examined. There was no significant relation between sod, cat, gst, or mt expression and Hg:Se molar ratios. cat and sod expression were significantly related to increases in percent MeHg, relative to THg; however, gst and mt expression were not significantly altered. This suggests that incorporating biomarkers containing Se may be a better indicator than non-selenium-containing proteins of assessing the long-term effect of Hg and the interactions between Hg and Se in the livers of fish, such as northern pike, especially when molar concentrations of Se are greater than Hg.
| S-EPMC10057176 | biostudies-literature
Project description:Teleost fishes, thanks to their rapid evolution of sex determination mechanisms, provide remarkable opportunities to study the formation of sex chromosomes and the mechanisms driving the birth of new master sex determining (MSD) genes. However, the evolutionary interplay between the sex chromosomes and the MSD genes they harbor is rather unexplored. We characterized a male-specific duplicate of the anti-Müllerian hormone (amh) as the MSD gene in Northern Pike (Esox lucius), using genomic and expression evidence as well as by loss-of-function and gain-of-function experiments. Using RAD-Sequencing from a family panel, we identified Linkage Group (LG) 24 as the sex chromosome and positioned the sex locus in its sub-telomeric region. Furthermore, we demonstrated that this MSD originated from an ancient duplication of the autosomal amh gene, which was subsequently translocated to LG24. Using sex-specific pooled genome sequencing and a new male genome sequence assembled using Nanopore long reads, we also characterized the differentiation of the X and Y chromosomes, revealing a small male-specific insertion containing the MSD gene and a limited region with reduced recombination. Our study reveals an unexpectedly low level of differentiation between a pair of sex chromosomes harboring an old MSD gene in a wild teleost fish population, and highlights both the pivotal role of genes from the amh pathway in sex determination, as well as the importance of gene duplication as a mechanism driving the turnover of sex chromosomes in this clade.
| S-EPMC6726246 | biostudies-literature
Project description:BackgroundPikes, members of genus Esox, are widespread freshwater predators of the northern hemisphere, and important sport fish also. From the Carpathian basin only one species, the northern pike (E. lucius) is noted. At the same time the pike stocks living in this area show high level of phenotypic variance (e.g. various body pattern) and its growth varies highly both among and within populations. These features usually explained by the environmental diversity of the area. Whereas we think that genetic reasons -e.g. the appearance of other/new pike species in the area- may also be responsible for these observed features. Since as no detailed information have been published from the pike populations of this area, so far; we conducted phylogenetic and morphological assay on 88 pike specimens, collected from 49 Middle Danubian sampling sites.ResultsOur phylogenetic surveys showed that the northern pike appear in the study area solely, but all the three of its major lineages (Northern, Circumpolar, Southern) were indicated. Only six specimens represent the Northern lineage, collected from the western part of the study area. The Circumpolar and Southern lineages were common in the Carpathian basin, but the Southern lineage showed higher levels of haplotype diversity than the Circumpolar clade. Which indicates that only the Southern lineage is native in the area, while the other two groups could have appeared in the Middle Danubian system either spontaneously or by human introduction. Moreover, the different clades appeared in the same populations, suggesting the opportunity of inter-lineage hybridisation. From the studied morphologicalal features, the number of scales on the lateral line and the head length showed significant differences among the lineages. At the same time the body pattern of the studied individuals seems to be rather influenced by the ontogenic changes than phylogeny.ConclusionsThe high phenotypic variability of Middle Danubian northern pike populations may be due that all of its three major clades appeared and came in secondary contact in the area. In the within watershed spread of the non-native lineages the human stocking/transfer may play a considerable role.
| S-EPMC10127386 | biostudies-literature
Project description:The aim of this sequencing experiment was to make available liver tissue expression for selected fish species, northern pike (Esox lucius, Eluc), coho salmon (Oncorhynchus kisutch, Okis) and Arctic charr (Salvelinus alpinus, Salp), for comparative expression studies between the species. Samples in replicate of four were sacrificed according to protocols at each of the facilities from where samples were obtained. RNA was extracted from samples and Illumina TruSeq Stranded mRNA libraries were built. Sequencing was performed in two passes on an Illumina HiSeq2500, paired-end 125bp reads. Processed count tables per species as raw counts, FPKM, or TPM, were generated from read alignment to the NCBI genomes of the respective species using STAR and gene level counting using RSEM and NCBI gene annotation.
2020-04-30 | E-MTAB-8962 | biostudies-arrayexpress
Project description:A growing number of studies have been investigating the influence of contemporary environmental factors on population genetic structure, but few have addressed the issue of spatial patterns in the variable intensity of factors influencing the extent of population structure, and particularly so in aquatic ecosystems. In this study, we document the landscape genetics of northern pike (Esox lucius), based on the analysis of nearly 3000 individuals from 40 sampling sites using 22 microsatellites along the Lake Ontario - St. Lawrence River system (750 km) that locally presents diverse degrees of interannual water level variation. Genetic structure was globally very weak (F ST = 0.0208) but spatially variable with mean level of differentiation in the upstream section of the studied area being threefold higher (F ST = 0.0297) than observed in the downstream sector (F ST = 0.0100). Beside interannual water level fluctuation, 19 additional variables were considered and a multiple regression on distance matrices model (R (2) = 0.6397, P < 0.001) revealed that water masses (b = 0.3617, P < 0.001) and man-made dams (b = 0.4852, P < 0.005) reduced genetic connectivity. Local level of interannual water level stability was positively associated to the extent of genetic differentiation (b = 0.3499, P < 0.05). As water level variation impacts on yearly quality and localization of spawning habitats, our study illustrates how temporal variation in local habitat availability, caused by interannual water level fluctuations, may locally decrease population genetic structure by forcing fish to move over longer distances to find suitable habitat. This study thus represents one of the rare examples of how environmental fluctuations may influence spatial variation in the extent of population genetic structure within a given species.
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Project description:Determining the success of invasive species eradication efforts is challenging because populations at very low abundance are difficult to detect. Environmental DNA (eDNA) sampling has recently emerged as a powerful tool for detecting rare aquatic animals; however, detectable fragments of DNA can persist over time despite absence of the targeted taxa and can therefore complicate eDNA sampling after an eradication event. This complication is a large concern for fish eradication efforts in lakes since killed fish can sink to the bottom and slowly decay. DNA released from these carcasses may remain detectable for long periods. Here, we evaluated the efficacy of eDNA sampling to detect invasive Northern pike (Esox lucius) following piscicide eradication efforts in southcentral Alaskan lakes. We used field observations and experiments to test the sensitivity of our Northern pike eDNA assay and to evaluate the persistence of detectable DNA emitted from Northern pike carcasses. We then used eDNA sampling and traditional sampling (i.e., gillnets) to test for presence of Northern pike in four lakes subjected to a piscicide-treatment designed to eradicate this species. We found that our assay could detect an abundant, free-roaming population of Northern pike and could also detect low-densities of Northern pike held in cages. For these caged Northern pike, probability of detection decreased with distance from the cage. We then stocked three lakes with Northern pike carcasses and collected eDNA samples 7, 35 and 70 days post-stocking. We detected DNA at 7 and 35 days, but not at 70 days. Finally, we collected eDNA samples ~ 230 days after four lakes were subjected to piscicide-treatments and detected Northern pike DNA in 3 of 179 samples, with a single detection at each of three lakes, though we did not catch any Northern pike in gillnets. Taken together, we found that eDNA can help to inform eradication efforts if used in conjunction with multiple lines of inquiry and sampling is delayed long enough to allow full degradation of DNA in the water.
| S-EPMC5023132 | biostudies-literature
Project description:Intraspecific genetic admixture occurs when previously separated populations within a species start interbreeding, and it can have either positive, negative, or neutral effects on reproductive performance. As there currently is no reliable predictor for the outcome of admixture, an increased knowledge about admixture effects in different species and populations is important to increase the understanding about what determines the response to admixture. We tested for effects of admixture on F1 offspring quality in three subpopulations of pike (Esox lucius). Gametes were collected in the field, and eggs from each female were experimentally fertilized with milt from a male from each population (one "pure" and two "admixed" treatments). Three offspring quality measures (hatching success, fry survival, and fry length) were determined and compared between (a) pure and admixed population combinations and (b) the sex-specific treatments within each admixed population combination (based on the origin of the male and female, respectively). The results suggested that although there were no overall effects of admixture on offspring quality, the consequences for a given population combination could be sex-specific and thus differ depending on which of the parents originated from one or the other population. All offspring quality traits were influenced by both maternal ID and paternal ID. Sex- and individual-specific effects can have implications for dispersal behavior and gene flow between natural populations, and are important to consider in conservation efforts.
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