Combined effects of salinity and temperature on survival and growth during the early life cycle of the rock oyster Saccostrea cuccullata (Born, 1778)

Abstract

Temperature and salinity are among the critical factors affecting the survival and growth of bivalve larvae. The combined effects of temperature and salinity on the embryonic and larval development of the rock oyster Saccostrea cuccullata (von Born, 1778) in culture conditions were investigated in a laboratory study on Inhaca Island, Mozambique. A factorial experimental design tested three temperatures (24, 30 and 34 ºC) and three salinities (30, 35 and 40 parts per thousand) over a seven-day period. Larval survival and growth (in height and length) were assessed by regular sampling by counting and measurement of larvae under an optical microscope equipped with a micrometric scale. Significantly higher larval survival was observed at the combination of 30 °C and 35 salinity. However, the mid-range temperature (30 ºC) and highest salinity (40) resulted in faster growth of the larvae. The lowest temperature (24 ºC) negatively affected growth regardless of salinity level and survival decreased linearly with increasing salinities. The present results will aid in the understanding of the environmental factors behind the natural recruitment of spat of S. cuccullata and contribute to the optimization of rearing protocols for the larval culture of this oyster species.