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Louis Bernatchez - One of the best experts on this subject based on the ideXlab platform.
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adaptation and acclimation of traits associated with swimming capacity in lake whitefish Coregonus clupeaformis ecotypes
BMC Evolutionary Biology, 2016Co-Authors: Nicolas Martin, Anne C Dalziel, Martin Laporte, Louis BernatchezAbstract:Improved performance in a given ecological niche can occur through local adaptation, phenotypic plasticity, or a combination of these mechanisms. Evaluating the relative importance of these two mechanisms is needed to better understand the cause of intra specific polymorphism. In this study, we reared populations of Lake Whitefish (Coregonus clupeaformis) representing the’normal’ (benthic form) and the ‘dwarf’ (derived limnetic form) ecotypes in two different conditions (control and swim-training) to test the relative importance of adaptation and acclimation in the differentiation of traits related to swimming capacity. The dwarf whitefish is a more active swimmer than the normal ecotype, and also has a higher capacity for aerobic energy production in the swimming musculature. We hypothesized that dwarf fish would show changes in morphological and physiological traits consistent with reductions in the energetic costs of swimming and maintenance metabolism. We found differences in traits predicted to decrease the costs of prolonged swimming and standard metabolic rate and allow for a more active lifestyle in dwarf whitefish. Dwarf whitefish evolved a more streamlined body shape, predicted to lead to a decreased drag, and a smaller brain, which may decrease their standard metabolic rate. Contrary to predictions, we also found evidence of acclimation in liver size and metabolic enzyme activities. Results support the view that local adaptation has contributed to the genetically-based divergence of traits associated with swimming activity. Presence of post-zygotic barriers limiting gene flow between these ecotype pairs may have favoured repeated local adaptation to the limnetic niches.
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genetic structure and within generation genome scan analysis of fisheries induced evolution in a lake whitefish Coregonus clupeaformis population
Conservation Genetics, 2016Co-Authors: Jobran Chebib, Louis Bernatchez, Sebastien Renaut, Sean M. RogersAbstract:Size-selective harvest may lead to over-exploitation of commercial fisheries, but the population genetic and evolutionary consequences of such practices remain poorly understood. We investigated the role of within-generation selection in a historically over-exploited Lake Whitefish (Coregonus clupeaformis) population associated with fisheries-induced evolution in Lesser Slave Lake, Alberta, Canada. DNA from archived scales of Lake Whitefish collected between 1986 and 1999 were genotyped at 20 microsatellites and 51 gene-coding SNPs associated with growth and reproduction. We found that the Lake Whitefish in Lesser Slave Lake consisted of a single genetic stock, with microsatellites revealing more temporal than spatial variation in allele frequencies. A comparative genome scan among replicate cohorts from commercially harvested versus random survey samples identified one candidate SNP under divergent selection. This SNP localized within a gene encoding nucleoside diphosphate kinase A, a protein associated with differential growth. Collectively, the results highlight the utility of within-generation genome scans towards investigating the evolutionary consequences of harvest in the wild.
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adaptation and acclimation of aerobic exercise physiology in lake whitefish ecotypes Coregonus clupeaformis
Evolution, 2015Co-Authors: Anne C Dalziel, Nicolas Martin, Martin Laporte, Helga Guderley, Louis BernatchezAbstract:The physiological mechanisms underlying local adaptation in natural populations of animals, and whether the same mechanisms contribute to adaptation and acclimation, are largely unknown. Therefore, we tested for evolutionary divergence in aerobic exercise physiology in laboratory bred, size-matched crosses of ancestral, benthic, normal Lake Whitefish (Coregonus clupeaformis) and derived, limnetic, more actively swimming "dwarf" ecotypes. We acclimated fish to constant swimming (emulating limnetic foraging) and control conditions (emulating normal activity levels) to simultaneously study phenotypic plasticity. We found extensive divergence between ecotypes: dwarf fish generally had constitutively higher values of traits related to oxygen transport (ventricle size) and use by skeletal muscle (percent oxidative muscle, mitochondrial content), and also evolved differential plasticity of mitochondrial function (Complex I activity and flux through Complexes I-IV and IV). The effects of swim training were less pronounced than differences among ecotypes and the traits which had a significant training effect (ventricle protein content, ventricle malate dehydrogenase activity, and muscle Complex V activity) did not differ among ecotypes. Only one trait, ventricle mass, varied in a similar manner with acclimation and adaptation and followed a pattern consistent with genetic accommodation. Overall, the physiological and biochemical mechanisms underlying acclimation and adaptation to swimming activity in Lake Whitefish differ.
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mapping phenotypic expression and transmission ratio distortion qtl using rad markers in the lake whitefish Coregonus clupeaformis
Molecular Ecology, 2013Co-Authors: Pierrealexandre Gagnaire, Eric Normandeau, Scott A Pavey, Louis BernatchezAbstract:The evolution of reproductive isolation in an ecological context may involve multiple facets of species divergence on which divergent selection may operate. These include variation in quantitative phenotypic traits, regulation of gene expression, and differential transmission of particular allelic combinations. Thus, an integrative approach to the speciation process involves identifying the genetic basis of these traits, in order to understand how they are affected by divergent selection in nature and how they ultimately contribute to reproductive isolation. In the Lake Whitefish (Coregonus clupeaformis), dwarf and normal species pairs sympatrically occur in several North American postglacial lakes. The limnetic dwarf whitefish distinguishes from its normal benthic relative by numerous life history, behavioural, morphological and gene expression traits, in relation with the exploitation of distinct ecological niches. Here, we have applied the RAD-Sequencing method to a hybrid backcross family to reconstruct a high-density genetic linkage map and perform QTL mapping in the Lake Whitefish. The 3061 cM map encompassed 3438 segregating RAD markers distributed over 40 linkage groups, for an average resolution of 0.89 cM. We mapped phenotypic and expression QTL underlying ecologically important traits as well as transmission ratio distortion QTL, and identified genomic regions harbouring clusters of such QTL. A narrow genomic region strongly associated with sex determination was also evidenced. Positional and functional information revealed in this study will be useful in ongoing population genomic studies to illuminate our understanding of the genomic architecture of reproductive isolation between whitefish species pairs.
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bac library construction screening and clone sequencing of lake whitefish Coregonus clupeaformis salmonidae towards the elucidation of adaptive species divergence
Molecular Ecology Resources, 2011Co-Authors: Julie Jeukens, Brian Boyle, Irena Kukavicaibrulj, Jerome Stcyr, Roger C Levesque, Louis BernatchezAbstract:Genomic DNA sequences and other genomic resources are essential towards the elucidation of the genomic bases of adaptive divergence and reproductive isolation. Here, we describe the construction, characterization and screening of a nonarrayed BAC library for lake whitefish (Coregonus clupeaformis). We then show how the combined use of BAC library screening and next-generation sequencing can lead to efficient full-length assembly of candidate genes. The lake whitefish BAC library consists of 181,050 clones derived from a single heterozygous fish. The mean insert size is 92 Kb, representing 5.2 haploid genome equivalents. Ten BAC clones were isolated following a quantitative real-time PCR screening approach that targeted five previously identified candidate genes. Sequencing of these clones on a 454 GS FLX system yielded 178,000 reads with a mean length of 358 bp, for a total of 63.8 Mb. De novo assembly and annotation then allowed retrieval of contigs corresponding to each candidate gene, which also contained up- and/or downstream noncoding sequences. These results suggest that the lake whitefish BAC library combined with next-generation sequencing technologies will be key resources to achieve a better understanding of both adaptive divergence and reproductive isolation in lake whitefish species pairs as well as salmonid evolution in general.
J F Klaverkamp - One of the best experts on this subject based on the ideXlab platform.
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toxicology of dietary nickel in lake whitefish Coregonus clupeaformis
Aquatic Toxicology, 2002Co-Authors: M D Ptashynski, Robert E Evans, J F Klaverkamp, R M Pedlar, C L BaronAbstract:The sublethal toxicity associated with exposure of adult lake whitefish (Coregonus clupeaformis) to diets containing 0, 10, 100, and 1000 μg Ni per g for 10, 31, and 104 days was assessed through the measurement of responses, through a range of levels of biological organization. The accumulation and distribution of Ni in these fish are described in the previous manuscript (Ptashynski and Klaverkamp, 2001. Aquat. Toxicol. in press). Hematological parameters, including concentrations of glucose and hemoglobin and hematocrit, were not different between control and treated fish. Organ and whole organism parameters, including LSI, growth, and condition factor, were also unaffected. Histopathological lesions in kidney and liver proved to be the most sensitive and reliable indicators of Ni exposure. In livers of treated fish, areas of focal necrosis and altered bile ducts were observed. Histological alterations were observed throughout the posterior kidneys, in glomeruli, tubules, collecting ducts, and hematopoietic tissue, in fish fed medium and high dose diets. In whitefish kidneys, the frequency (%) of altered distal tubules and fields of views with alterations increased with the dose and duration of exposure. Significant increases in metallothionein concentrations were observed in intestine of whitefish fed the high dose diet on day 10, but these increases were not sustained. Significant increases in lipid peroxide concentrations were also observed in plasma of whitefish fed the high dose diet on day 31, but were not observed on day 104. These biochemical responses to dietary Ni require further evaluation. To evaluate exposure of natural populations of fish to Ni, analysis of Ni in kidney and liver and assessment of renal and hepatic histopathology are recommended for use in field bio-monitoring programs.
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accumulation and distribution of dietary uranium in lake whitefish Coregonus clupeaformis
Aquatic Toxicology, 2002Co-Authors: H M Cooley, J F KlaverkampAbstract:Adult lake whitefish (Coregonus clupeaformis) were fed As contaminated diets at nominal concentrations of 0, 1, 10 and 100 μg As/g food (d.w.) for 10, 30 and 64 days. Liver, kidney, stomach, intestine, pyloric caeca, gallbladder, skin and scales were analyzed for As content. The pattern of As accumulation in fish tissues was influenced by reduced feed consumption beginning on day 45 by fish fed the 100 μg As/g food. Significant As accumulation occurred in all tissues examined from fish exposed to the 100 μg As/g food for 30 days, with the exception of gallbladder. After 30 days of exposure, the highest concentration of As was observed in pyloric caeca of fish fed the 100 μg As/g food. Significant accumulation of As occurred in livers and scales of fish fed concentrations of As as low as 10 μg/g for 30 and 64 days. Muscle, gonad, spleen, gills and bone of lake whitefish fed a control diet for 10 days and 100 μg As/g food for 10, 30 and 64 days were also analyzed for As content. As concentrations increased in gonads, spleen and gills of fish fed the 100 μg As/g food for 30 days. Increased concentrations of As were observed in bone of fish fed the high dose food after each duration of exposure. As concentrations did not increase in muscle of fish after 10, 30 or 64 days of exposure. The following manuscript (Pedlar et al., 2001) documents toxicological effects observed in these fish. Analyses of As in pyloric caeca, intestine, liver and scales are recommended to evaluate the bioavailability of As to freshwater fish in environmental monitoring programs.
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toxicological effects of dietary arsenic exposure in lake whitefish Coregonus clupeaformis
Aquatic Toxicology, 2002Co-Authors: R M Pedlar, Robert E Evans, J F Klaverkamp, M D PtashynskiAbstract:Abstract Adult lake whitefish were fed As contaminated diets at nominal concentrations of 0, 1, 10, and 100 μg As/g food (dry weight) for 10, 30, and 64 days. Reduced feed consumption was observed in lake whitefish fed the 100 μg As/g food, beginning on day 45 of exposure. The accumulation and distribution of As in these fish are described in the previous manuscript [Pedlar, R.M., Klaverkamp, J.F., 2001. The accumulation and distribution of dietary arsenic in lake whitefish ( Coregonus clupeaformis ). Aquat. Toxicol., in press]. At the molecular level of organization, metallothionein (MT) induction occurred in lake whitefish fed the 100 μg As/g food after 10 and 30 days, and in fish fed the 1 and 10 μg As/g diets for 64 days. Dietary As exposure did not have a significant effect on plasma lipid peroxide (LPO) concentrations. At the tissue and organ level, mean liver somatic index decreased significantly in lake whitefish fed the 100 μg As/g food for 64 days. Blood parameters (hematocrit, hemoglobin concentration, red blood cell count, mean cell volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration) were not affected by exposure to As contaminated diets. Liver and gallbladder histopathologies were observed in lake whitefish fed all As contaminated diets after each duration of exposure. Histopathology observed in liver included nuclear, architectural and structural alterations, areas of inflammation, and focal necrosis. Sloughing of the epithelium, dilation of vascular elements, inflammation, edema, fibrosis, and increased width of the submucosa were some of the alterations observed in gallbladders of lake whitefish fed As contaminated diets. Both organs were sensitive to As exposure, as damage occurred with exposure to dietary concentrations of As as low as 1 μg/g. Whole organism parameters were unaltered by dietary As exposure. Based on the results of this study, histopathological alterations in liver and gallbladder, and hepatic MT induction may be useful indicators of As toxicity in environmental monitoring programs that also measure As concentrations in those tissues.
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the accumulation distribution and toxicological effects of dietary arsenic exposure in lake whitefish Coregonus clupeaformis and lake trout salvelinus namaycush
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2002Co-Authors: R M Pedlar, Robert E Evans, M D Ptashynski, C L Baron, Kerry Wautier, J F KlaverkampAbstract:Abstract A 20-day experiment was conducted to compare the accumulation, distribution, and toxicological effects of dietary As, as arsenate, in lake whitefish (LWF, Coregonus clupeaformis) and lake trout (LT, Salvelinus namaycush). Results of this experiment were used to design an experiment of longer duration in which one of the fish species was selected and exposed three times per week to lower dietary As doses. In the present study each treatment group was exposed to a combination of one of three doses of As (0, 100, or 1000 μg As/g) and one of two types of diet, no brine shrimp (NS) or with brine shrimp (WS) for a total of eight dosing events. Brine shrimp were added to determine whether their presence enhanced consumption of As-contaminated food. Modified feeding behavior occurred in both fish species fed As contaminated diets, with the exception of the 100 μg As/g NS food. Brine shrimp addition did not affect feed consumption of the As contaminated diets. Significant As accumulation occurred in stomach, pyloric caeca, intestine, liver, kidney, and gallbladder, but not in bile or muscle. As exposure did not have a significant effect on hepatic and renal metallothionein concentrations. Concentrations of lipid peroxides were only significantly elevated in the plasma of LT fed the 1000 μg As/g WS food. Liver somatic indices decreased significantly in both species, whereas hematological parameters were not affected in either species. Histological lesions occurred in gallbladder, liver, kidney, pyloric caeca and intestine from LWF. These lesions were not observed in LT; however, gallbladders were not examined in this species. Weight gain was lower in both species fed As contaminated diets, however, condition factors were not affected.
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accumulation distribution and toxicology of dietary nickel in lake whitefish Coregonus clupeaformis and lake trout salvelinus namaycush
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2001Co-Authors: M D Ptashynski, Robert E Evans, R M Pedlar, C L Baron, Kerry Wautier, J F KlaverkampAbstract:Abstract An 18-day experiment was conducted to investigate the uptake and sublethal toxicity of dietary Ni in adult lake whitefish (LWF, Coregonus clupeaformis) and lake trout (LT, Salvelinus namaycush) fed diets containing 0, 1000 and 10 000 μg Ni/g, prepared with and without brine shrimp. The results of this experiment were used to design an experiment of longer duration in which one of the fish species was selected and exposed to lower dietary Ni doses. In the present study feed refusal was observed in LT and LWF fed 10 000 μg Ni/g, after three and 4–5 feedings, respectively. LT fed Ni-contaminated diets exhibited different patterns of Ni accumulation than LWF. Increased Ni concentrations in all LWF tissues, except the intestine, were associated with increased doses of Ni. Copper and Zn concentrations in kidney and liver of LWF were altered. Metallothionein concentrations in kidneys of LT fed 1000 μg Ni/g and 10 000 μg Ni/g and LWF fed 10 000 μg Ni/g and in livers of LWF fed 10 000 μg Ni/g (diet without shrimp only) increased significantly. Increased lipid peroxide production in the plasma of LT fed 10 000 μg Ni/g was observed. Blood glucose and electrolytes were affected by Ni exposure. Histopathological alterations were observed in kidneys of LWF fed low and high dose diets, livers of whitefish fed high dose diets, and intestines of LWF fed high dose diets and LT fed low and high dose diets. LT fed high dose diets exhibited significant decreases in weight.
Sean M. Rogers - One of the best experts on this subject based on the ideXlab platform.
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genetic structure and within generation genome scan analysis of fisheries induced evolution in a lake whitefish Coregonus clupeaformis population
Conservation Genetics, 2016Co-Authors: Jobran Chebib, Louis Bernatchez, Sebastien Renaut, Sean M. RogersAbstract:Size-selective harvest may lead to over-exploitation of commercial fisheries, but the population genetic and evolutionary consequences of such practices remain poorly understood. We investigated the role of within-generation selection in a historically over-exploited Lake Whitefish (Coregonus clupeaformis) population associated with fisheries-induced evolution in Lesser Slave Lake, Alberta, Canada. DNA from archived scales of Lake Whitefish collected between 1986 and 1999 were genotyped at 20 microsatellites and 51 gene-coding SNPs associated with growth and reproduction. We found that the Lake Whitefish in Lesser Slave Lake consisted of a single genetic stock, with microsatellites revealing more temporal than spatial variation in allele frequencies. A comparative genome scan among replicate cohorts from commercially harvested versus random survey samples identified one candidate SNP under divergent selection. This SNP localized within a gene encoding nucleoside diphosphate kinase A, a protein associated with differential growth. Collectively, the results highlight the utility of within-generation genome scans towards investigating the evolutionary consequences of harvest in the wild.
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integrating qtl mapping and genome scans towards the characterization of candidate loci under parallel selection in the lake whitefish Coregonus clupeaformis
Molecular Ecology, 2004Co-Authors: Sean M. Rogers, Louis BernatchezAbstract:As natural selection must act on underlying genetic variation, discovering the number and location of loci under the influence of selection is imperative towards understanding adaptive divergence in evolving populations. Studies employing genome scans have hypothesized that the action of divergent selection should reduce gene flow at the genomic locations implicated in adaptation and speciation among natural populations, yet once ‘outlier’ patterns of variation have been identified the function and role of such loci needs to be confirmed. We integrated adaptive QTL mapping and genomic scans among diverging sympatric pairs of the lake whitefish (Coregonus clupeaformis) species complex in order to test the hypothesis that differentiation between dwarf and normal ecotypes at growth-associated QTL was maintained by directional selection. We found evidence of significantly high levels of molecular divergence among eight growth QTL where two of the strongest candidate loci under the influence of directional selection exhibited parallel reductions of gene flow over multiple populations.
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Isolation, characterization and cross-salmonid amplification of 31 microsatellite loci in the lake whitefish (Coregonus clupeaformis, Mitchill)
Molecular Ecology Notes, 2004Co-Authors: Sean M. Rogers, Marie‐hélène Marchand, Louis BernatchezAbstract:Coregonine fish represent the most successful evolutionary lineage of salmonids with Coregonus as the most speciose salmonid genus inhabiting numerous postglacial lakes across the northern hemisphere. We isolated and characterized 31 polymorphic microsatellite loci in Coregonus clupeaformis with an average number of 5.3 alleles per locus (range three to eight) and an overall expected heterozygosity of 0.74 ± 0.11. Two loci revealed significant linkage associations through analyses of mapping families. Six additional salmonid taxa assessed for cross-species amplification revealed between 18 and 26 positive amplifications and between two and 12 polymorphic loci per species.
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genetically based phenotype environment association for swimming behavior in lake whitefish ecotypes Coregonus clupeaformis mitchill
Evolution, 2002Co-Authors: Sean M. Rogers, V Gagnon, Louis BernatchezAbstract:Abstract Studies of phenotype-environment associations in adaptive radiation have focused largely on morphological traits related to resource-based phenotypic differences. The genetic basis of adaptive behaviors implicated in population divergence remains poorly understood, as few studies have tested the hypothesis of behavioral phenotype-environment associations. We provide evidence of a phenotype-environment association for differential adaptive swimming behaviors through experiments conducted on dwarf, normal, and hybrid lake whitefish (Coregonus clupeaformis). Highly significant differences were observed for depth selection, directional changes, and burst swimming, implicating a genetic basis for these behaviors. Hybrid crosses revealed that depth selection is under additive genetic control, while dominance effects were suggested for directional changes and burst swimming. Estimates for the genetic basis of behavioral differentiation from an animal model were consistent with these observations. Compar...
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combining the analyses of introgressive hybridisation and linkage mapping to investigate the genetic architecture of population divergence in the lake whitefish Coregonus clupeaformis mitchill
Genetica, 2001Co-Authors: Sean M. Rogers, David I Campbell, S J E Baird, Roy G Danzmann, Louis BernatchezAbstract:Adaptation and reproductive isolation, the engines of biological diversity, are still elusive when discussing the genetic bases of speciation. Namely, the number of genes and magnitude of selection acting positively or negatively on genomic traits implicated in speciation is contentious. Here, we describe the first steps of an ongoing research program aimed at understanding the genetic bases of population divergence and reproductive isolation in the lake whitefish (Coregonus clupeaformis). A preliminary linkage map originating from a hybrid cross between dwarf and normal ecotypes is presented, whereby some of the segregating AFLP markers were found to be conserved among natural populations. Maximum-likelihood was used to estimate hybrid indices from non-diagnostic markers at 998 AFLP loci. This allowed identification of the most likely candidate loci that have been under the influence of selection during the natural hybridisation of whitefish originating from different glacial races. As some of these loci could be identified on the linkage map, the possibility that selection of traits in natural populations may eventually be correlated to specific chromosomal regions was demonstrated. The future prospects and potential of these approaches to elucidate the genetic bases of adaptation and reproductive isolation among sympatric ecotypes of lake whitefish is discussed.
Steven A. Pothoven - One of the best experts on this subject based on the ideXlab platform.
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Spatial variation in feeding ecology of age-0 lake whitefish Coregonus clupeaformis in Lake Huron
Journal of Freshwater Ecology, 2020Co-Authors: Steven A. Pothoven, Chris OldsAbstract:Age-0 lake whitefish Coregonus clupeaformis stomachs from western Lake Huron were examined in 2018 to evaluate spatial variation in feeding ecology. Overall, age-0 lake whitefish had narrow diet ni...
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the influence of ontogeny and prey abundance on feeding ecology of age 0 lake whitefish Coregonus clupeaformis in southeastern lake michigan
Ecology of Freshwater Fish, 2020Co-Authors: Steven A. PothovenAbstract:A shift towards oligotrophic conditions in Lake Michigan has led to concern that altered trophic pathways are leading to lower early life survival and recruitment for Lake Whitefish (Coregonus clupeaformis). This study evaluated ontogenetic shifts in age‐0 Lake Whitefish diets and evaluated how feeding ecology and the amount of food eaten varied with prey abundance and composition at a site in southeastern Lake Michigan during 2014–2017. Although prey densities varied among years, cyclopoid copepods were overall the most abundant prey available. In turn, cyclopoids were the predominant prey item in diets each year, particularly for the smallest larval Lake Whitefish. However, there was a tendency for the importance of cyclopoids to decline somewhat in each diet index as fish grew and other prey such as calanoid copepods, Bosminidae, Daphniidae and/or chironomids increased in importance. High zooplankton abundance, especially high cyclopoid abundance, available to the small size groups of Lake Whitefish (<21 mm) in 2014 was associated with high food mass/fish, high number of zooplankton eaten/fish, and low incidence of empty stomachs compared with 2015–2017. As fish grew, the impact of food abundance on prey consumption diminished somewhat, indicating that the relationship between fish feeding ecology and the prey environment can change quickly with fish size during the early life period.
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net trophic transfer efficiencies of polychlorinated biphenyl congeners to lake whitefish Coregonus clupeaformis from their food
Environmental Toxicology and Chemistry, 2007Co-Authors: Charles P Madenjian, D V Oconnor, Richard R Rediske, James P Okeefe, Steven A. PothovenAbstract:Lake whitefish (Coregonus clupeaformis) were fed rainbow smelt (Osmerus mordax) in four laboratory tanks over a 133-d experiment. At the start of the experiment, 10 to 14 of the fish in each tank were sacrificed, and the concentrations of 40 polychlorinated biphenyl (PCB) congeners within these fish were determined. Polychlorinated biphenyl congener concentrations were also determined in the 15 lake whitefish remaining in each of the four tanks at the end of the experiment as well as in the rainbow smelt fed to the lake whitefish. Each lake whitefish was weighed at the start and the end of the experiment, and the amount of food eaten by the lake whitefish during the experiment was tracked. Using these measurements, net trophic transfer efficiency (γ) from the rainbow smelt to the lake whitefish in each of the four tanks was calculated for each of the 40 PCB congeners. Results showed that γ decreased exponentially as log KOW for the congeners increased from 6 to 8. Further, γ averaged 0.70 for the tetrachloro congeners but averaged only 0.45 for the higher chlorinated congeners.
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energy density of lake whitefish Coregonus clupeaformis in lakes huron and michigan
Environmental Biology of Fishes, 2006Co-Authors: Steven A. Pothoven, Charles P Madenjian, Thomas F Nalepa, Richard R Rediske, Philip J SchneebergerAbstract:We collected lake whitefish Coregonus clupeaformis off Alpena and Tawas City, Michigan, USA in Lake Huron and off Muskegon, Michigan USA in Lake Michigan during 2002–2004. We determined energy density and percent dry weight for lake whitefish from both lakes and lipid content for Lake Michigan fish. Energy density increased with increasing fish weight up to 800 g, and then remained relatively constant with further increases in fish weight. Energy density, adjusted for weight, was lower in Lake Huron than in Lake Michigan for both small (≤800 g) and large fish (>800 g). Energy density did not differ seasonally for small or large lake whitefish or between adult male and female fish. Energy density was strongly correlated with percent dry weight and percent lipid content. Based on data from commercially caught lake whitefish, body condition was lower in Lake Huron than Lake Michigan during 1981–2003, indicating that the dissimilarity in body condition between the lakes could be long standing. Energy density and lipid content in 2002–2004 in Lake Michigan were lower than data for comparable sized fish collected in 1969–1971. Differences in energy density between lakes were attributed to variation in diet and prey energy content as well as factors that affect feeding rates such as lake whitefish density and prey abundance.
Mohamed Faisal - One of the best experts on this subject based on the ideXlab platform.
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spatio temporal dynamics of gastrointestinal helminths infecting four lake whitefish Coregonus clupeaformis stocks in northern lakes michigan and huron u s a
Journal of Parasitology, 2011Co-Authors: Mohamed Faisal, Walied Fayed, Abdelaziz Nour, Travis O BrendenAbstract:abstract: This study was undertaken to identify the community composition, structure, and dynamics of helminths infecting the gastrointestinal tract (GIT) of lake whitefish (Coregonus clupeaformis) collected from 4 sites in northern lakes Huron (Cheboygan and De Tour Village) and Michigan (Big Bay de Noc and Naubinway) from fall 2003 through summer 2006. A total of 21,203 helminths was retrieved from the GITs of 1,284 lake whitefish. Approximately 42% (SE = 1.4%) of the examined lake whitefish were infected with at least 1 helminth species in their GIT, with a mean intensity of 39.4 worms/fish (SE = 0.3) and a mean abundance of 16.4 worms/fish (SE = 0.1). Collected helminths appeared to be generalists and consisted of 2 phyla (Acanthocephala and Cestoda) and 5 species (Acanthocephalus dirus, Neoechinorhynchus tumidus, Echinorhynchus salmonis, Cyathocephalus truncatus, and Bothriocephalus sp.). Lake whitefish from Lake Huron on average had greater infection prevalences, abundances, and intensities t...
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isolation of aeromonas salmonicida subspecies salmonicida from lake whitefish Coregonus clupeaformis inhabiting lakes michigan and huron
Journal of Great Lakes Research, 2010Co-Authors: Thomas P Loch, Mohamed FaisalAbstract:Herein we describe the first report of Aeromonas salmonicida subspecies salmonicida infections in lake whitefish (Coregonus clupeaformis) collected from four sites in lakes Michigan and Huron, Michigan, USA. The bacterium was isolated from the kidneys of four out of 1286 lake whitefish that were tested over a three-year period. The four isolates were phenotypically similar to one another and exhibited the morphological, colonial, and biochemical traits typical of A. salmonicida subspecies salmonicida. Amplification of 16S rRNA genes specific to A. salmonicida subspecies salmonicida via polymerase chain reaction and subsequent gel electrophoresis analyses confirmed the identity of the four lake whitefish isolates. Clinical signs associated with infection included extensive external hemorrhaging, exophthalmia, splenomegaly, splenic and renal congestion, fibrinous adhesions of the spleen and liver, and hemorrhagic enteritis. Histopathological examination of infected fish revealed multi-focal hemorrhage and infiltration of lymphocytes and histiocytes in subdermal adipose tissues and musculature. A low infection incidence of A. salmonicida salmonicida in Great Lakes lake whitefish does not preclude the fact that overt signs of disease were observed in infected individuals and that lake whitefish may act as a reservoir for this bacterium that is highly pathogenic to numerous fish species.
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widespread infection of lake whitefish Coregonus clupeaformis with the swimbladder nematode cystidicola farionis in northern lakes michigan and huron
Journal of Great Lakes Research, 2010Co-Authors: Mohamed Faisal, Mark P Ebener, Walied Fayed, Travis O Brenden, Abdelaziz Noor, Gregory M Wright, Michael L JonesAbstract:We estimated the prevalence, intensity, and abundance of swimbladder nematode infection in 1281 lake whitefish (Coregonus clupeaformis) collected from four sites in northern lakes Huron (Cheboygan and DeTour Village) and Michigan (Big Bay de Noc and Naubinway) from fall 2003 through summer 2006. Morphological examination of nematode egg, larval, and mature stages through light and scanning electron microscopy revealed characteristics consistent with that of Cystidicola farionis Fischer 1798. Total C. farionis prevalence was 26.94%, while the mean intensity and abundance of infection was 26.72 and 7.21 nematodes/fish, respectively. Although we detected C. farionis in all four stocks that were examined, Lake Huron stocks generally had higher prevalence, intensity, and abundance of infection than Lake Michigan stocks. A distinct seasonal fluctuation in prevalence, abundance, and intensity of C. farionis was observed, which does not coincide with reported C. farionis development in other fish species. Lake whitefish that were heavily infected with C. farionis were found to have thickened swimbladder walls with deteriorated mucosa lining, which could affect swimbladder function. Whether C. farionis infection may be negatively impacting lake whitefish stocks in the Great Lakes is unclear; continued monitoring of C. farionis infection should be conducted to measure responses of lake whitefish stocks to infection levels.
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assessment of renibacterium salmoninarum infections in four lake whitefish Coregonus clupeaformis stocks from northern lakes huron and michigan
Journal of Great Lakes Research, 2010Co-Authors: Mohamed Faisal, Mark P Ebener, Thomas P Loch, Travis O Brenden, Gregory M Wright, Alaa Eldin Eissa, Michael L JonesAbstract:Lake whitefish (Coregonus clupeaformis) from four stocks in northern Lakes Michigan and Huron were collected seasonally from fall 2003 through summer 2006 and examined for the presence of Renibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD), using culture techniques on modified kidney disease medium (MKDM) and the quantitative enzyme-linked immunosorbent assay (Q-ELISA). R. salmoninarum was detected in 62.31% (according to Q-ELISA) of the 1284 examined lake whitefish, with some fish displaying the typical signs of BKD, such as renal congestion, swelling, and whitish nodules. Kidney cultures on MKDM yielded bacteria with morphological and biochemical characteristics identical to those of R. salmoninarum recovered from other Great Lakes fish species, as well as those from other parts of the world. Isolate identification was confirmed via nested polymerase chain reaction. Antibiograms demonstrated high sensitivity to enrofloxacin and ciprofloxacin, sensitivity to oxytetracycline, erythromycin, azithromycin, chloramphenicol, novobiocin, and carbenicillin, and resistance to polymyxin B, clindamycin, and kanamycin. Statistical analysis of R. salmoninarum prevalence and intensities revealed significant interactions among stocks, years and sampling seasons, with highest prevalence generally in fall and frequent wide variation in prevalence and intensity from one season to the next for a particular stock. It was surprising to find that the prevalence of R. salmoninarum exceeded 50% in the four stocks, much higher than originally thought. Moreover, a positive association between R. salmoninarum intensity and the abundance of the swimbladder nematode, Cystidicola farionis, was identified. Our findings suggest that Great Lakes lake whitefish are vulnerable to serious fish pathogens.
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spatial and temporal dynamics of lake whitefish Coregonus clupeaformis health indicators linking individual based indicators to a management relevant endpoint
Journal of Great Lakes Research, 2010Co-Authors: Tyler Wagner, Michael T Arts, Mark P Ebener, Mohamed Faisal, Travis O Brenden, Gregory M Wright, Michael L Jones, Dale C HoneyfieldAbstract:We examined the spatial and temporal dynamics of health indicators in four lake whitefish (Coregonus clupeaformis) stocks located in northern lakes Michigan and Huron from 2003 to 2006. The specific objectives were to (1) quantify spatial and temporal variability in health indicators; (2) examine relationships among nutritional indicators and stock-specific spatial and temporal dynamics of pathogen prevalence and intensity of infection; and (3) examine relationships between indicators measured on individual fish and stock-specific estimates of natural mortality. The percent of the total variation attributed to spatial and temporal sources varied greatly depending on the health indicator examined. The most notable pattern was a downward trend in the concentration of highly unsaturated fatty acids (HUFAs), observed in all stocks, in the polar lipid fraction of lake whitefish dorsal muscle tissue over the three study years. Variation among stocks and years for some indicators were correlated with the prevalence and intensity of the swimbladder nematode Cystidicola farionis, suggesting that our measures of fish health were related, at some level, with disease dynamics. We did not find relationships between spatial patterns in fish health indicators and estimates of natural mortality rates for the stocks. Our research highlights the complexity of the interactions between fish nutritional status, disease dynamics, and natural mortality in wild fish populations. Additional research that identifies thresholds of health indicators, below (or above) which survival may be reduced, will greatly help in understanding the relationship between indicators measured on individual fish and potential population-level effects.