Search

Temperature variation is affecting fish biodiversity worldwide, causing changes in geographic distribution, phenotypic structure, and even species extinction. Incubation is a critical stage for stenothermic species, which are vulnerable to large temperature fluctuations, and its effects on the phenotype at later developmental stages are understudied, despite the fact that the phenotype being essential for organism ecology and evolution. In this study, we tested the effects of heat shocks during the embryonic period on the phenotype of Arctic charr (Salvelinus alpinus). We repeatedly quantified multiple phenotypic traits, including morphology, development, and behavior, over a period of 4 months, from hatching to juvenile stage in individuals that had experienced heat shocks (+ 5°C on 24 h, seven times) during their embryonic stage and those that had not. We found that heat shocks led to smaller body size at hatching and a lower sociability. Interestingly, these effects weakened throughout the development of individuals and even reversed in the case of body size. We also found an accelerated growth rate and a higher body condition in the presence of heat shocks. Our study provides evidence that heat shocks experienced during incubation can have long‐lasting effects on an individual's phenotype. This highlights the importance of the incubation phase for the development of ectothermic organisms and suggests that temperature fluctuations may have significant ecological and evolutionary implications for Arctic charr. Given the predicted increase in extreme events and the unpredictability of temperature fluctuations, it is critical to further investigate their effects on development by examining fluctuations that vary in frequency and intensity. [ABSTRACT FROM AUTHOR]

This study examined the abiotic and biotic characteristics of ecosystems that allow expression of a life history called ferox trout, the colloquial name given to brown trout Salmo trutta adopting a piscivorous life history strategy, an apex predator in post-glacial lakes in northern Europe. One hundred and ninety-two lakes in Scotland show evidence of currently, or historically, supporting ferox S. trutta; their presence was predicted in logistic models by larger and deeper lakes with a large catchment that also support populations of Arctic charr Salvelinus alpinus. [ABSTRACT FROM AUTHOR]

The growth in captivity of a wild Welsh strain (Llyn Cowlyd) of Arctic charr Salvelinus alpinus was compared to that of a commercial Scottish strain over the course of a 12 month experiment. At the conclusion of the study, the Welsh strain had a lower mass and condition factor than the commercial fish, but a similar length. Aspects of the growth and population structure of the Welsh strain imply that it could be a subject for aquaculture development, but such practises will be dependant on further work on selection and broodstock development. [ABSTRACT FROM AUTHOR]

The association of genetic markers linked to the sex-determining locus (SEX) was investigated in five Arctic charr Salvelinus alpinus full sib families, all originating from the Fraser River strain, Labrador, Canada. Two distinct sex-linkage classes were identified: type I (two families), with previously reported markers on linkage group 4 (AC-4) linked with SEX; and type II (three families), with two unlinked segments of the AC-4 linkage group, but with markers in only one cluster associated with SEX. Large differences in recombination rates, pseudolinkage assembly or various chromosomal rearrangements may explain these findings. [ABSTRACT FROM AUTHOR]

Summer habitat use by sympatric Arctic charr Salvelinus alpinus, young Atlantic salmon Salmo salar and brown trout Salmo trutta was studied by two methods, direct underwater observation and electrofishing, across a range of habitats in two sub-arctic rivers. More Arctic charr and fewer Atlantic salmon parr were observed by electrofishing in comparison to direct underwater observation, perhaps suggesting a more cryptic behaviour by Arctic charr. The three species segregated in habitat use. Arctic charr, as found by direct underwater observation, most frequently used slow (mean ±s.d. water velocity 7·2 ± 16·6 cm s−1) or often stillwater and deep habitats (mean ±s.d. depth 170·1 ± 72·1 cm). The most frequently used mesohabitat type was a pool. Young Atlantic salmon favoured the faster flowing areas (mean ±s.d. water velocity 44·0 ± 16·8 cm s−1 and depth 57·1 ± 19·0 cm), while brown trout occupied intermediate habitats (mean ±s.d. water velocity 33·1 ± 18·6 cm s−1 and depth 50·2 ± 18·0 cm). Niche overlap was considerable. The Arctic charr observed were on average larger (total length) than Atlantic salmon and brown trout (mean ±s.d. 21·9 ± 8·0, 10·2 ± 3·1 and 13·4 ± 4·5 cm). Similar habitat segregation between Atlantic salmon and brown trout was found by electrofishing, but more fishes were observed in shallower habitats. Electrofishing suggested that Arctic charr occupied habitats similar to brown trout. These results, however, are biased because electrofishing was inefficient in the slow-deep habitat favoured by Arctic charr. Habitat use changed between day and night in a similar way for all three species. At night, fishes held positions closer to the bottom than in the day and were more often observed in shallower stream areas mostly with lower water velocities and finer substrata. The observed habitat segregation is probably the result of interference competition, but the influence of innate selective differences needs more study. [ABSTRACT FROM AUTHOR]

To evaluate whether paternal effects occur on offspring traits, eggs from Arctic charr Salvelinus alpinus were fertilized with similar amount of sperm from size-matched dominant and subordinate males, in a nested design. Eggs fertilized by subordinate fathers resulted in more offspring produced than eggs fertilized by the same amount of sperm from dominant fathers. Yet, paternal status showed no significant effect on measurements of larvae total length, yolk area and yolk red intensity. [ABSTRACT FROM AUTHOR]

The effects of formalin and ethanol preservation on the δ13C and δ15N isotope signatures of Arctic charr Salvelinus alpinus muscle tissue were examined. The lipid content of the tissue samples studied ranged from 3·6 to 6·1% and was not correlated with the magnitude of observed isotopic shifts in preserved samples. Ethanol and formalin significantly depleted and enriched, respectively, the δ13C isotope signatures of preserved tissues when compared to control samples. Ethanol did not significantly enrich δ15N signatures in comparison to controls, whereas formalin did. A meta-analysis of multiple species effects further demonstrated significant preservation effects in fish tissue. Statistical analysis of data obtained by correcting preserved tissue isotope signatures with literature, bootstrapped or meta-analysis derived correction factors demonstrated significant differences between corrected and control sample isotope signatures or failure to produce a unity slope when the data sets were regressed against one another. Species-specific, bootstrapped linear correction models resulted in no such errors. Results suggest that species-specific correction methods should be used for fishes because of the known wide variation in fish tissue lipid content and composition. Accordingly, the use of pilot studies will be required to develop correction factors that properly adjust for preservation effects when interpreting temporal patterns in historic analyses of food webs. [ABSTRACT FROM AUTHOR]

The relationship between parasite infection and breeding ornamentation in an Arctic charr Salvelinus alpinus population was examined. Interrelationships between the intensities of parasites with different dietary transmission routes suggested that hosts were segregated by habitat and diet preferences. That is, intensities of parasites transmitted through intermediate hosts that share habitat were, in both sexes, positively interrelated. Negative interrelationships in the intensities of parasites transmitted through different hosts were found only in females. The intensity of breeding colouration was positively correlated with intensities of amphipod-transmitted parasites in both sexes. Intensities of parasites transmitted through copepods showed no relationship to morphological or ornamental characters. Seen in the context of morphology and ornaments of previously described sympatric populations of Arctic charr, these relationships suggested that individual variation in niche background may provide a source for the initial variation in morphology and secondary sexual traits leading to sympatric speciation through sexual selection. [ABSTRACT FROM AUTHOR]

Food ingestion to assess dominance status, indicated that dominant Arctic charrSalvelinus alpinusdisplayed significantly higher white muscle pyruvate kinase(PK) and lactate dehydrogenase(LDH) activities compared to subordinate fish[PK = 429·57 ± 76·37v. 331·00 ± 61·73 U g−1 tissue( P = 0·022) and LDH = 929·33 ± 61·03v. 775·25 ± 110·96 U g−1 tissue;( P = 0·0007)]. [ABSTRACT FROM AUTHOR]

Differences in gonadal development and time of spawning were found in two coexisting morphotypes of Arctic charr Salvelinus alpinus in Kalandsvatnet, Norway. Spawning depth and some main life-history variables also differed. These observations suggest that the two morphotypes do not interbreed freely. [ABSTRACT FROM AUTHOR]

No difference in attraction was observed in sibling Artic charr Salvelinus alpinus between water scented by dominant or subordinate major histocompability complex (MHC) identical fish observed in a two-choice fluviarium. In a second experiment, MHC identical sibling donors were given different types of food pellets before the preference test. The test fish showed a significant attraction to the sibling given the same kind of food as the test fish itself during the first 6 h of the fluviarium tests. The results suggest that diet has an influence on the odours released and can, in addition to MHC related odours, be used for information relating to group member identity. [ABSTRACT FROM AUTHOR]

Like the spermatozoa of most other fish species spawning in fresh water, Arctic charr Salvelinus alpinus sperm were short-lived (mean 42 s) after activation and their swimming speed declined rapidly during this period, e.g. from a mean speed of 106 μm s−1 at 10 s after activation in fresh water to 21 μm s−1 only 20 s later. Ovarian fluid significantly influenced sperm longevity (duration of forward mobility), per cent motility, swimming speed and the linearity of sperm movement. All of these variables generally increased as the concentration of ovarian fluid increased from 0 to 50%, even though ovarian fluid is more than three times as viscous as fresh water. It is concluded that ovarian fluid enhances sperm movement in this species and thus has the potential to influence both fertilization success and the outcome of sperm competition. Copyright 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

Aggressive interactions were initially higher in groups comprised of equally sized large and intermediate Arctic charr Salvelinus alpinus than in groups of small sized individuals and in groups with a normal size distribution. Size composition had no effect on growth. Copyright 2002 The Fisheries Society of the British Isles. Published by Elsevier Science. All rights reserved. [Copyright &y& Elsevier]

Planktivorous and benthivorous morphs of wild Arctic charr Salvelinus alpinus from Loch Rannoch, Perthshire, Scotland, reared in the laboratory from artificially fertilized eggs under identical conditions, were morphologically distinct (based on a series of head measurements) from an early age. For some morphometric characters, these differences became more marked with increasing body size, reflecting differences in the allometric growth patterns of the two forms. These data show that the observed phenotypic differences between these two trophic variants were, to some extent at least, inherited. Thus it is concluded that the mechanisms regulating expression of phenotype in the sympatric morphs of Loch Rannoch are significantly different from the environmentally determined body size polymorphisms reported from Norway but are closer to the more completely divergent forms from Thingvalavatn, Iceland. [Copyright &y& Elsevier]

The growth of Arctic charr Salvelinus alpinus in five high altitude lakes differed between lakes during the first 2 years but was similar thereafter. The average temperature during the summer had a direct effect on growth and an indirect effect on the productivity level of the lakes, particularly on the abundance of planktonic crustaceans. The results highlight the importance of planktonic crustacea in the growth of Arctic charr. [Copyright &y& Elsevier]

Stable isotopes of carbon and nitrogen were used to examine differences in the feeding ecology of sympatric morphotypes of Arctic charr Salvelinus alpinus from Lake Hazen, Ellesmere Island, in the Canadian High Arctic. Large and small morphotypes possessed significantly different carbon and nitrogen signatures with large-form Arctic charr being more depleted in 13C and more enriched in 15N than the small-form. Isotope and stomach content analyses yielded consistent results and indicated short- and long-term reliance on fish as a food for large Arctic charr. Large-form individuals predate on juveniles but do not predate on small-form individuals ≥250 mm. The observed cannibalism by large-form individuals, therefore, does not act to maintain the bimodal length-frequency distribution in Lake Hazen. Bimodality is argued to arise for ecological reasons connected with differing habitat use by the morphotypes and the associated differences in resource consumption opportunities. [Copyright &y& Elsevier]

Smolt of anadromous Arctic charr Salvelinus alpinus (L.) migrating from Storvatn, northern Norway, had a similar feeding intensity as resident Arctic charr from the benthic- and pelagic zone in early summer in fresh water. While smolts fed mostly on surface insects, however, resident Arctic charr had a more broader diet consisting mostly of chironomids, Bosmina sp., benthic prey and surface insects. This indicates that Arctic charr smolts have adopted a surface oriented feeding behaviour prior to their sea migration. [Copyright &y& Elsevier]