TY - JOUR
T1 - Fluid regulation and physiological adjustments in the winter skate, Leucoraja ocellata, following exposure to reduced environmental salinities
AU - Sulikowski, James A.
AU - Treberg, Jason R.
AU - Howell, W. Huntting
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2003/4/1
Y1 - 2003/4/1
N2 - Winter skates, Leucoraja ocellata, exposed to 80% and 50% seawater (SW) exhibited rapid and significant weight gains followed by a slight recovery to new steady state levels within 8 days. Skates were acclimated at each salinity (100% SW [N = 16], 80% SW [N = 8], 50% SW [N = 8]), anesthetized (MS222) and bled from the caudal vein. In 100% SW, skate plasma (930 mOsm/kg) was slightly hyperosmotic to the external medium (922 mOsm/kg). Plasma osmolality decreased with seawater dilution, but became increasingly hyperosmotic to the bathing media. The environmental dilutions resulted in significant, but disproportionate changes in plasma Cl-, P-, Na+, Ca+, Mg+, trimethylamine oxide (TMAO) and urea concentrations. Mean corpuscular [Hb] and milliliter RBC water measurements suggest that skate red cells swelled less at each dilution than predicted for a passive erythrocyte osmometer. Concentrations of the major RBC solutes K+, urea, TMAO and Cl- decreased by 8, 25, 5 and 21%, respectively in 80% SW. In 50% SW, K+, urea, TMAO and Cl- concentrations decreased by 9, 47, 36 and 15%, respectively. Quantitatively, the other measured intracellular electrolytes (Mg+, Na+, P- and Ca+) also exhibited disproportionate changes in concentration. Our results indicate that L. ocellata is a euryhaline elasmobranch that can tolerate significant reduction in the external salinity through the release of both ions and urea from the extracellular compartments while retaining electrolytes at the expense of urea in the intracellular compartment.
AB - Winter skates, Leucoraja ocellata, exposed to 80% and 50% seawater (SW) exhibited rapid and significant weight gains followed by a slight recovery to new steady state levels within 8 days. Skates were acclimated at each salinity (100% SW [N = 16], 80% SW [N = 8], 50% SW [N = 8]), anesthetized (MS222) and bled from the caudal vein. In 100% SW, skate plasma (930 mOsm/kg) was slightly hyperosmotic to the external medium (922 mOsm/kg). Plasma osmolality decreased with seawater dilution, but became increasingly hyperosmotic to the bathing media. The environmental dilutions resulted in significant, but disproportionate changes in plasma Cl-, P-, Na+, Ca+, Mg+, trimethylamine oxide (TMAO) and urea concentrations. Mean corpuscular [Hb] and milliliter RBC water measurements suggest that skate red cells swelled less at each dilution than predicted for a passive erythrocyte osmometer. Concentrations of the major RBC solutes K+, urea, TMAO and Cl- decreased by 8, 25, 5 and 21%, respectively in 80% SW. In 50% SW, K+, urea, TMAO and Cl- concentrations decreased by 9, 47, 36 and 15%, respectively. Quantitatively, the other measured intracellular electrolytes (Mg+, Na+, P- and Ca+) also exhibited disproportionate changes in concentration. Our results indicate that L. ocellata is a euryhaline elasmobranch that can tolerate significant reduction in the external salinity through the release of both ions and urea from the extracellular compartments while retaining electrolytes at the expense of urea in the intracellular compartment.
KW - Elasmobranch
KW - Erythrocyte
KW - Extracellular
KW - Hematologic properties
KW - Osmoregulation
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U2 - 10.1023/A:1023918231020
DO - 10.1023/A:1023918231020
M3 - Article
AN - SCOPUS:0038007827
SN - 0378-1909
VL - 66
SP - 339
EP - 348
JO - Environmental Biology of Fishes
JF - Environmental Biology of Fishes
IS - 4
ER -