A panel of 12 polymorphic microsatellite markers was developed for the population genetic studies of white-spotted char Salvelinus leucomaenis. The four population samples examined consisted of 48 individuals each, and were collected in different geographical regions, including Sakhalin Island, Kunashir Island, and Iturup Island (two samples). The total number of different-sized alleles at different loci varied in the range of 2-31. In the population of white-spotted char subjected to strong anthropogenic pressure allelic diversity and expected heterozygosity indices were found to be lower than in wild populations of this species. The considerable genetic subdivision of different insular populations of white-spotted char observed was consistent with isolation by the distance model.
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Zoolog Sci
April 2024
Graduate School of Environmental Science, Hokkaido University, Hokkaido 060-0810, Japan.
Assessing the impacts of parasites on wild fish populations is a fundamental and challenging aspect of the study of host-parasite relationships. , a genus of ectoparasitic copepods, mainly infects salmonid species. This genus, which is notorious in aquaculture, damages host fishes, but its impacts under natural conditions remain largely unknown or are often considered negligible.
View Article and Find Full Text PDFSci Rep
September 2023
Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Sapporo, Hokkaido, 062-0922, Japan.
Increases in prey population size can affect the physiology and ecology of upper-trophic level organisms. This phenomenon is known as a bottom-up effect. For example, the increased abundance of prey resources can trigger physiological (internal) changes in predators, such as improvements in nutritional status.
View Article and Find Full Text PDFJ Fish Biol
May 2023
Laboratory of Marine Biology, Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1, Minato-Cho, Hakodate, 041-8611, Japan.
Downstream displacement, the passive downstream dispersal of riverine organisms, can generate evolutionary pressures that selectively remove susceptible individuals from upstream habitats. These evolutionary pressures may accumulate over time in fish populations situated upstream of a tall check dam that displaced fish are unable to swim over and can be diluted by the homing of displaced individuals in the absence of such barriers. Here, we conducted interpopulation comparisons between above-dam and unrestricted open-stream populations of the juvenile white-spotted charr Salvelinus leucomaenis to test the hypothesis that above-dam juveniles possess more advantageous traits that reduce downstream displacement than open-stream juveniles.
View Article and Find Full Text PDFTerrestrial resource pulses can significantly affect the community dynamics of freshwater ecosystems. Previously, its effect on the river community is considered to be stronger in summer, whereas weaker in winter when terrestrial invertebrates are less abundant. The movement of the terrestrial earthworms is triggered in winter, so they may be supplied to winter rivers as terrestrial resource pulse, but little is known about it.
View Article and Find Full Text PDFFolia Parasitol (Praha)
November 2022
Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan.
Salmincola markewitschi Shedko et Shedko, 2002 (Copepoda: Lernaeopodidae) is an ectoparasitic copepod mainly infecting the buccal cavities of white-spotted charr Salvelinus leucomaenis (Pallas) (Salmonidae). This species has only been recorded from Northeast Asia, where a morphologically similar congener Salmincola carpionis (Krøyer, 1837) is also distributed, using the same host species. These copepods are hard to distinguish from each other because of their similarities.
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