Osmotic and ionic hemolymph concentrations of bathyal and abyssal amphipods of Lake Baikal (Siberia) in relation to water depth |
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Authors: | I Zerbst-Boroffka T Grospietsch I Mekhanikova V Takhteev |
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Institution: | Institut für Biologie der Freien Universit?t Berlin, – Stoffwechsel- und Systemphysiologie, Grunewaldstr. 34, 12 165 Berlin, Germany e-mail: agsystem@zedat.fu-berlin.de Tel.: +49-30-83853989; Fax: +49-30-83854640, DE Limnological Institute Irkutsk, Ulan Batorskaja 3, 66 4033 Irkutsk, Russia, RU State University Irkutsk, Zoology of Invertebrates, Suche Batora ulitza 5, Irkutsk 66 4003, Russia, RU
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Abstract: | We studied the adaptive variations of the hemolymph concentrations in relation to water depth and pressure using deep-dwelling
amphipods from Lake Baikal. Hemolymph osmolality was determined in six bathyal and abyssal species immediately after capture
when values come closest to the habitat concentrations. In three species, hemolymph osmolalities correlated positively with
depth of capture. Prevalent ions in the hemolymph are sodium and chloride. Lactate, our indicator for capture stress, was
highest after trawling (2–6 mM) and lowest after retrieval from cages (0–0.6 mM). Acclimation to different pressure was studied
by exposing the specimens to different water depths over several days. Hemolymph concentrations did not change after acclimation
to surface pressure in the sublittoral Acanthogammarus albus, a native also to shallow water, but decreased by 30–80 mosmol/kg H2O in the bathyal and abyssal species Acanthogammarus grewingki, Acanthogammarus reicherti, and Parapallasea lagowskii. Similarly, hemolymph osmolality decreased in A. reicherti and P. lagowskii originating from deep water, when acclimated to reduced water depth, and, in A. reicherti hemolymph osmolality reached its original high value when returned to the depth of capture. Higher hemolymph osmolalities
and NaCl concentrations, demonstrated here for the first time, may provide selective advantages to abyssal species.
Accepted: 24 August 2000 |
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Keywords: | Lake Baikal Abyss Osmolality Ionic concentration Amphipods |
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