The effect of temperature and salinity on the larval development of Stenorhynchus seticornis (Brachyura: Inachidae) reared in the laboratory

Larvae of Stenorhynchus seticornis were reared in the laboratory in a factorial experiment employing three temperatures (22, 25 and 28 degrees C) and three salinities (30, 35 and 40%) to determine the effects of these variables on the survival and duration of the larval stages. Larvae from five females were subdivided in six groups of 10 and reared in glass bowls containing 125 ml filtered and UV-irradiated seawater at different temperature-salinity combinations. Larvae were transferred daily to clean bowls with newly hatched Artemia nauplii, and the number of moults and mortality within each bowl was recorded. Complete larval development of S. seticornis occurred under all experimental conditions, except at temperature 28 degrees C and salinity 35%. Salinity affected percentage survival of the two zoeal stages, but not that of the megalopa. Survival of the second zoeal stage, the megalopa, and the complete development to the first crab was affected by temperature, with the greatest survival occurring at 25 degrees C. Duration of the two zoeal stages, the megalopa, and development to the first crab stage showed a gradual reduction with increasing temperature. Development from hatching to the first crab stage required 17 to 31 days and was inversely related to temperature, averaging 26.9 days at 22 degrees C, 21.0 days at 25 degrees C and 19.7 days at 28 degrees C. Salinity affected the duration of the first zoeal stage only.