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Seasonal dynamics of Atlantic herring (Clupea harengus L.) populations spawning in the vicinity of marginal habitats.

Eggers F, Slotte A, Libungan LA, Johannessen A, Kvamme C, Moland E, Olsen EM, Nash RD - PLoS ONE (2014)

Bottom Line: In comparison, spawning of Landvik herring peaked in May-June with high proportions found inside the lake, which could be explained by local adaptations to the environmental conditions and seasonal changes of this marginal habitat.In comparison, outside the 3 km long narrow channel connecting the lake with the neighboring fjord, no anoxic conditions were found.Temperature at 0-5 m depth increased significantly over the season in both habitats, from 7 to 14 °C outside and 5 to 17 °C inside the lake.

View Article: PubMed Central - PubMed

Affiliation: Institute of Marine Research, Bergen, Norway; Department of Biology, University of Bergen, Bergen, Norway.

ABSTRACT
Gillnet sampling and analyses of otolith shape, vertebral count and growth indicated the presence of three putative Atlantic herring (Clupea harengus L.) populations mixing together over the spawning season February-June inside and outside an inland brackish water lake (Landvikvannet) in southern Norway. Peak spawning of oceanic Norwegian spring spawners and coastal Skagerrak spring spawners occurred in March-April with small proportions of spawners entering the lake. In comparison, spawning of Landvik herring peaked in May-June with high proportions found inside the lake, which could be explained by local adaptations to the environmental conditions and seasonal changes of this marginal habitat. The 1.85 km(2) lake was characterized by oxygen depletion occurring between 2.5 and 5 m depth between March and June. This was followed by changes in salinity from 1-7‰ in the 0-1 m surface layer to levels of 20-25‰ deeper than 10 m. In comparison, outside the 3 km long narrow channel connecting the lake with the neighboring fjord, no anoxic conditions were found. Here salinity in the surface layer increased over the season from 10 to 25‰, whereas deeper than 5 m it was stable at around 35‰. Temperature at 0-5 m depth increased significantly over the season in both habitats, from 7 to 14 °C outside and 5 to 17 °C inside the lake. Despite differences in peak spawning and utilization of the lake habitat between the three putative populations, there was an apparent temporal and spatial overlap in spawning stages suggesting potential interbreeding in accordance with the metapopulation concept.

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Distribution of length, age and vertebral counts of different herring populations.Comparison between Norwegian spring spawning (NSS), Coastal Skagerrak spring spawning (CSS) and Landvik (LV) herring. Shaded areas are NSS herring inside Landvikvannet. The mean values are included.
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pone-0111985-g004: Distribution of length, age and vertebral counts of different herring populations.Comparison between Norwegian spring spawning (NSS), Coastal Skagerrak spring spawning (CSS) and Landvik (LV) herring. Shaded areas are NSS herring inside Landvikvannet. The mean values are included.

Mentions: Mean length, age and vertebral count (VS) differed significantly among the three herring populations (p<0.001, Figure 4). For age and length, pairwise comparisons were also significant (p<0.001), with the exception of CSS versus LV for age (p>0.05). The vertebral count differed significantly (p<0.001) for all pairwise comparisons. The main tendency was a significant increase in mean body length and VS when moving from LV to CSS to NSS, whereas men age decreased. The most common age was 3 years for NSS, CSS and LV herring. The 4 year olds were also abundant in CSS and LV herring, but hardly present among NSS herring.


Seasonal dynamics of Atlantic herring (Clupea harengus L.) populations spawning in the vicinity of marginal habitats.

Eggers F, Slotte A, Libungan LA, Johannessen A, Kvamme C, Moland E, Olsen EM, Nash RD - PLoS ONE (2014)

Distribution of length, age and vertebral counts of different herring populations.Comparison between Norwegian spring spawning (NSS), Coastal Skagerrak spring spawning (CSS) and Landvik (LV) herring. Shaded areas are NSS herring inside Landvikvannet. The mean values are included.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4221434&req=5

pone-0111985-g004: Distribution of length, age and vertebral counts of different herring populations.Comparison between Norwegian spring spawning (NSS), Coastal Skagerrak spring spawning (CSS) and Landvik (LV) herring. Shaded areas are NSS herring inside Landvikvannet. The mean values are included.
Mentions: Mean length, age and vertebral count (VS) differed significantly among the three herring populations (p<0.001, Figure 4). For age and length, pairwise comparisons were also significant (p<0.001), with the exception of CSS versus LV for age (p>0.05). The vertebral count differed significantly (p<0.001) for all pairwise comparisons. The main tendency was a significant increase in mean body length and VS when moving from LV to CSS to NSS, whereas men age decreased. The most common age was 3 years for NSS, CSS and LV herring. The 4 year olds were also abundant in CSS and LV herring, but hardly present among NSS herring.

Bottom Line: In comparison, spawning of Landvik herring peaked in May-June with high proportions found inside the lake, which could be explained by local adaptations to the environmental conditions and seasonal changes of this marginal habitat.In comparison, outside the 3 km long narrow channel connecting the lake with the neighboring fjord, no anoxic conditions were found.Temperature at 0-5 m depth increased significantly over the season in both habitats, from 7 to 14 °C outside and 5 to 17 °C inside the lake.

View Article: PubMed Central - PubMed

Affiliation: Institute of Marine Research, Bergen, Norway; Department of Biology, University of Bergen, Bergen, Norway.

ABSTRACT
Gillnet sampling and analyses of otolith shape, vertebral count and growth indicated the presence of three putative Atlantic herring (Clupea harengus L.) populations mixing together over the spawning season February-June inside and outside an inland brackish water lake (Landvikvannet) in southern Norway. Peak spawning of oceanic Norwegian spring spawners and coastal Skagerrak spring spawners occurred in March-April with small proportions of spawners entering the lake. In comparison, spawning of Landvik herring peaked in May-June with high proportions found inside the lake, which could be explained by local adaptations to the environmental conditions and seasonal changes of this marginal habitat. The 1.85 km(2) lake was characterized by oxygen depletion occurring between 2.5 and 5 m depth between March and June. This was followed by changes in salinity from 1-7‰ in the 0-1 m surface layer to levels of 20-25‰ deeper than 10 m. In comparison, outside the 3 km long narrow channel connecting the lake with the neighboring fjord, no anoxic conditions were found. Here salinity in the surface layer increased over the season from 10 to 25‰, whereas deeper than 5 m it was stable at around 35‰. Temperature at 0-5 m depth increased significantly over the season in both habitats, from 7 to 14 °C outside and 5 to 17 °C inside the lake. Despite differences in peak spawning and utilization of the lake habitat between the three putative populations, there was an apparent temporal and spatial overlap in spawning stages suggesting potential interbreeding in accordance with the metapopulation concept.

Show MeSH