Document Type : Original Article
Seikai National Fisheries Research Institute, Japan Fisheries Research and Education Agency, 1551-8 Tairamachi, Nagasaki, 851-2213, Japan
National Research Institute of Fisheries and Environment of Inland Sea, Japan Fisheries Research and Education Agency, 1760 Momoshima, Onomichi, Hiroshima, 722-0061, Japan
In the inner area of the Sea of Ariake, rearing experiments were conducted to examine how the survival rates of juveniles of three bivalve species (Anadara kagoshimensis, Ruditapes philippinarum, Atrina sp.) vary among sea areas and heights above the seabed. In three runs of the experiment, replicate samples of the three bivalves were kept in trays set at various heights above the seabed (range 0–40 cm) at one to six stations for 15–16 days. Results were as follows. (1) Survival rates varied among heights and stations more markedly for Atrina sp. than for A. kagoshimensis and R. philippinarum; (2) Atrina sp. always showed higher survival rates at greater heights above the seabed, whereas the other species did not always show this pattern. (3) Survival rates of Atrina sp. showed a different station-to-station variation pattern between experimental runs. (4) In statistical model selection, the spatial variations in the survival rate were not associated for either A. kagoshimensis or R. philippinarum with any of the environmental factors recorded (density of suspended solids, density of chlorophyll a, water temperature). In contrast, for Atrina sp. they were strongly and negatively associated with the spatial variations in density of suspended solids.