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Abstract

Identification of discrete stocks of Greenland halibut is an important aspect of proper fisheries exploitation. Available literature data indicated a lack of significant inter‑area differences between Greenland halibut populations from the Northeast Atlantic. To define the population diversity, two aspects were taken into account: enzyme‑genetic diversity and the concentration of heavy metals in tissues. Seven allozyme loci variations were used to characterize the genetic structure of four populations of Greenland halibut from the Western Barents Sea region. The samples were collected from the spawning area in the period when this species took migration to spawn. The sample RH4 was significantly different from the other samples collected from the same location (RH2 and RH3) and depth for over two days. Another sample (RH8), collected from the nearby area 6 days later was similar to the samples RH2, RH3. We noticed a significant divergence between the sample RH4 and the three remaining samples, where the value of the index FST fluctuated about 0.40 and approximately 0.01 between three similar populations. This genetic fluctuation negates the thesis of a panmictic character of the Western Atlantic population. Feeding groups of Greenland halibut are moving along the Barents Sea shelf and they are exposed to different heavy metals concentrations according to the food preferences or the exact place of feeding. We identified similar concentrations of heavy metals, i.e., Zn, Cu, Cd, and Pb in all samples. Trace metal analysis of aquatic organisms from the Barents Sea can provide important information on the degree of environmental contamination, and the potential impact of seafood consumption.
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Authors and Affiliations

Barbara Wojtasik
1
Agnieszka Kijewska
2
Monika Mioduchowska
1 3
Barbara Mikuła
4
Jerzy Sell
1

  1. University of Gdansk, Department of Genetics and Biosystematics, Gdansk, Poland
  2. Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland
  3. University of Gdansk, Department of Marine Plankton Research, Gdynia, Poland
  4. University of Silesia, Department of Analytical Chemistry, Faculty of Chemistry, Katowice, Poland
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Abstract

Genetic variability of two populations of Arctic freshwater crustacean Lepidurus arcticus (Crustacea, Notostraca) occuring in small tundra reservoirs near the Polish Polar Sta− tion in Hornsund (Spitsbergen) was studied. The allozyme polimorphism analysis of 11 en− zyme systems indicates a considerable distinctness and genetically heterogeneous character of the populations of L. arcticus inhabiting freshwater reservoirs of similar hydrological con− ditions situated close to each other (2 km). Our research revealed a complicated and geneti− cally heterogeneous character of the populations. Three hypotheses about genetic structure and type of reproduction were tested: hypothesis M – the free transfer without assigning a clone for particular reservoir and the lack of doublemutations; hypothesis I – separation of in− dividuals between reservoirs and the possibility of doublemutations; hypothesis S – presence of partial sexual reproduction in the population, probably with males. In conclusion participa− tion ofmales in reproduction is probable, despite their presence was not recorded in our study. Males usually occur in low numbers or not every year. The populations' clonal structure as well as the genetic diversity typical of species reproducing sexually was observed. The Hardy−Weinberg genetic equilibrium is maintained as new clonal lines appear due to the ge− netic diversity increasing incidentally as a result of sexual reproduction.

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Authors and Affiliations

Barbara Wojtasik
Magdalena Bryłka-Wołk

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