. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Medium (mEq/1) E. Medium (mEq/1) Figure 3. Byihnitnu'ci thermydron. Variations in hemolymph osmola- lit\ (A: ) (osmotic pressure in mosm/kg) and ionic concentrations (B to F) (in mEq • 1~') after hemolymph osmolality stabilization (about 15-24 h), in relation to the osmolality or ionic concentration of the medium. Time of exposure to the different media was 24 h (A) or 15-24 h (B to F). Error bars: mean ± SD;;;: 3 to 12 individuals; isoconcentration lines are drawn. Discussion Salinity tolerance The limited number of ava
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Medium (mEq/1) E. Medium (mEq/1) Figure 3. Byihnitnu'ci thermydron. Variations in hemolymph osmola- lit\ (A: ) (osmotic pressure in mosm/kg) and ionic concentrations (B to F) (in mEq • 1~') after hemolymph osmolality stabilization (about 15-24 h), in relation to the osmolality or ionic concentration of the medium. Time of exposure to the different media was 24 h (A) or 15-24 h (B to F). Error bars: mean ± SD;;;: 3 to 12 individuals; isoconcentration lines are drawn. Discussion Salinity tolerance The limited number of available animals and lack of time and space on board the ship prevented long-term tolerance experiments. Specimens of Bythograen thermydron sur- vived for 24 h in a narrow range of salinities ranging from about 3 \7(( to 427cc. These crabs, unable to withstand a great extent of salinity fluctuations, are thus stenohaline animals. They share this feature with other species of decapods whose habitat is most often restricted to seawater, for ex- ample, the Majidae. the Cancridae. and the Calappidae (review in Mantel and Farmer, 1983: Pequeux, 1995). Acclimation time In B. thermydron, the time required to reach an osmotic steady-state after a sudden decrease in external salinity was about 15 to 24 h. This is short for a brachyuran crab, similar to the 15 h required for osmotic equilibration in osmocon- formers such as the Majidae Maja sp. and Hyas sp. trans- ferred to 75% seawater (Prosser and Brown, 1965). Osmotic- adaptation requires longer times in strongly osmoregulating species, such as 48 h in osmoregulating crabs (Charmantier, 1998) and up to 96 h in crayfish (Susanto and Charmantier, 2000). The short acclimation time found in B. thennvdron probably indicates a relatively high exchange of water and ions between the organism and the external medium and a high permeability of the body surface in this species; it also reflects the weak salinity stress applied. Hydromineral reg
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
