Role of external factors for cultivation of pacific oyster <i>Crassostrea gigas</i> at a hatchery in Primorye. 1. The influence of temperature on development, growth and survival of embryos and larvae

Abstract

The influence of temperature on development, growth and survival of pacific oyster Crassostrea gigas embryos and larvae is investigated in controlled conditions at a hatchery located in Peter the Great Bay (Japan Sea) — the TINRO subdivision for mariculture on Popov Island in July-August, 2019. The oyster embryos and larvae obtained from natural producers in the process of artificial spawning were grown under temperature of 21–22 оC (close to natural conditions in the coastal waters of Primorye) and 24–25 оC. The higher temperature had a positive effect on development and growth rate of embryos and larvae. Under the temperature of 24–25 оC, the embryogenesis was completed earlier by 2 hours, the transition to the D-veliger stage — by 8 hours, the stage of veliconch was reached in 1 day earlier, the stage of pediveliger — in 4 days earlier than under the temperature of 21–22 оC. The daily size increments were larger under the higher temperature, with the most significant differences at the stages of veliger (6.4 vs 4.2 µm day–1) and veliconch (14.3 vs 10.9 µm day–1), with no difference at the stage of pediveliger. The greatest average daily increment was reached with exotrophic nutrition (at the veliconch stage) in both cases. The larval mortality was higher under the higher temperature in 1.3 times at the stages from fertilized egg to D-veliger and in 1.4 times at the stages from D-veliger to pediveliger because of intensification of metabolic processes and the water pollution in the tanks for growing, with the largest difference at the stages of veliger and veliconch, as well, as the longest ones. There is concluded that the temperature of 24–25 оC lays within the range of optimal conditions for embryonic and larval development of pacific oyster (within the biokinetic zone) and this temperature is recommended for cultivation of this species in Primorye hatcheries, with selection of optimal parameters for the rearing.