Thermal limits of krill species from the high-Arctic Kongsfjord (Spitsbergen)
The high-Arctic Kongsfjord is influenced mainly by cold Arctic water but also by warmer Atlantic water masses. In recent years, the proportion of the Atlantic inflow from the south has increased. Concurrently, one temperate-boreal (Meganyctiphanes norvegica) and one subtropical-temperate (Nematoscel...
| Published in: | Marine Ecology Progress Series |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
Inter Research
2015
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| Subjects: | |
| Online Access: | https://epic.awi.de/id/eprint/38464/ http://www.int-res.com/abstracts/meps/v535/p89-98/ https://hdl.handle.net/10013/epic.46012 |
| Summary: | The high-Arctic Kongsfjord is influenced mainly by cold Arctic water but also by warmer Atlantic water masses. In recent years, the proportion of the Atlantic inflow from the south has increased. Concurrently, one temperate-boreal (Meganyctiphanes norvegica) and one subtropical-temperate (Nematoscelis megalops) krill species are now regularly found in the Kongsfjord, in addition to the previously prevailing arcto-boreal species Thysanoessa inermis and T. raschii. In view of the recent changes in these species’ biogeographic distributions, we compared their physiological tolerances. Using non-invasive optical oxygen sensors, respiration measurements served to characterize metabolic responses to temperature variations. Thysanoessa spp. appear more cold-stenotherm than the other 2 krill species: the upper level of respiratory capacity is reached at 12°C and they are less tolerant to decreasing oxygen concentrations. This finding is consistent with their arcto-boreal distribution. In contrast, M. norvegica and N. megalops showed a higher tolerance to temperature changes, a robust nutritional condition and sexual maturity. Such physiological plasticity may explain the recent northward expansion of their geographic range. |
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