Water intake, gut absorption and sodium fluxes in amphibious and aquatic fishes
1969; Pergamon Press; Volume: 30; Issue: 2 Linguagem: Inglês
10.1016/0010-406x(69)90808-1
ISSN1879-3029
Autores Tópico(s)Aquaculture Nutrition and Growth
Resumo1. With lowered external salinity, the drinking rates of the marine fish, Pelates quadrilineatus, decreased significantly from 9·57 ± 0·46 to 5·76 ± 0·87 μl/g per hr, whereas those of the almost terrestrial mud skipper, Periophthalmus vulgaris, increased from 3·55 ± 0·61 to 10·83 ± 2·15. Rates in three other species of marine or fresh-water fish were not related to external salinity. 2. Gross 22Na effluxes of both Periophthalmus and Pelates were similar, and linearly related to external salinity. 3. The adaptation of Periophthalmus appears to be behavioural rather than physiological. 4. Pelates gut ions, at two different external salinites, were highly variable, and indicated that water absorption is probably regulated at the gut wall rather than by drinking rate. Calcium appears to be excreted into the gut. 5. It is concluded that water drinking may also serve for elimination of substances, such as Ca, excreted into the gut.
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