The collection of natural spat, which is performed in various aquaculture farms in Japan, is expected to be introduced in various regions in the future, as it would lead to the development of sustainable aquaculture method with low cost, low transfer risk of pathogens as well as of harmful microalgae (Lagarde et al., 2017). Oyster farmers in Hiroshima Bay put collectors, mostly made of scallop ( Mizuhopecten yessoensis) shells, in the sea and use the spat settled on them for the farming by the raft method (Fujiya, 1970). ![]() gigas eggs develop rapidly after fertilization, becoming D-shaped larvae after 24 h, umbo larvae after 4 days, pediveliger larvae after 10 days after a total 10–14 days of planktonic life, they settle on the substrate and metamorphose into spat (Fujiya, 1970). Here, almost all the spat required for oyster farming are obtained by collection of naturally spawned spat during the summer (Arakawa, 1990). gigas farming area in Japan, and about 60% of Japan's oyster are produced in this bay. Japan is one of the world's leading oyster-producing countries after China and Republic of Korea, and the production of C. gigas, one of the most important marine economic animals, is farmed in many coastal areas of North and South America, Europe, Australia and East Asia, and its global aquaculture production has exceeded 550,000 metric ton per year since 1980 ( ). The Pacific oyster Crassostrea gigas (Thunberg), is a species originally distributed in Japan, China, the Korean Peninsula, and Sakhalin Island, with the type specimen having been collected in Japan. sustain the recruitment of oyster spat as an essential food. choctawhatcheeana was abundantly detected in the digestive tract of oyster larvae collected in the field, suggesting that Cyclotella spp. in sea water led to a successful larval settlement in both 20. ![]() The results of metabarcoding analysis indicated that increase in <10 μm size diatom Cyclotella spp. We also examined the species composition of 26.9 ☌ and chlorophyll a concentrations for 5 μg L −1. In order to elucidate the favorable environmental window for oyster spat collection, we investigated water quality parameters (water temperature, salinity and nutrients), abundance of larval food and success of larval settlement during the period of spat collection in Hiroshima Bay. Rafted aquaculture using natural spat of the native oyster is conducted in this bay and spat collection during the spawning season in summer is a key process for sustainable farming. ![]() Hiroshima Bay, located in the western part of the Seto Inland Sea, is the largest Pacific oyster Crassostrea gigas farming area in Japan.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |