Effects of development, temperature and salinity on metabolism in eggs and yolk-sac larvae of milkfish, Chanos chanos (Forsskål) |
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Authors: | W A Walsh C Swanson † C-S Lee |
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Institution: | The Oceanic Institute, P.O. Box 25280, Honolulu, HI 96825;Department of Biology, University of California, Los Angeles, CA 90024, U.S.A. |
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Abstract: | Oxygen uptake rates and yolk-inclusive dry weiGhts were measured during the egg and yolk-sac larval stages of milkfish, Chanos chanos (Forsskal). Oxygen uptake by eggs and yolk-sac larvae was measured to assess the effects of four salinities (20,25,30,35 ppt) at 28°C. The effects of three temperatures (23,28,33°C) on oxygen uptake by yolk-sac larvae were determined at a salinity of 35 ppt. Dry weights were measured throughout embryonic development at 28°C and the yolk-sac stage at 23.28 and 33°C. Oxygen uptake rates of eggs increased more than fivefold during embryogenesis (0.07±0.03 to 0.40 ± 03 μl O2 egg ?1 h ?1;blastula to prehatch stage). Larval oxygen uptake did not change with age but was affected by rearing temperature (0.33 ± 0.08, 0.44 ± 0.07 and 0.63 ± 0.13 μl O2 larva ?1 h?1 at 23, 28 and 33°C, respectively; Q10= 1.93). Acute temperature changes from 28 to 33°C caused significant increases in oxygen uptake by embryos (Q 10= 1.69–3.58) and yolk-sac larvae (Q 10=2.55). Salinity did not affect metabolic rates. Dry weight of eggs incubated at 28°C decreased 13% from fertilization to hatching. Incubation temperatures from 23–33°C did not affect dry weights at hatching. Rearing temperatures significantly affected the rate of larval yolk absorption (Q 10= 2.25). |
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Keywords: | Chanos chanos eggs yolk-sac larvae oxygen uptake rates dry weights |
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