緑川河口干潟におけるホトトギスガイの二次生産量の特徴

抄録

The Asian mussel, Arcuatula (Musculista) senhousia, forms dense population patches on sandy tidal flats. However, few studies have investigated its secondary production. Therefore, we investigated secondary production of the Asian mussel, as well as the temperature and salinity of water on the Midori river tidal flats, Kyushu, Japan, from April 2012 to July 2013. In this study, we discuss the characteristics of secondary production of A. senhousia and the influence of the mussel on primary producers. The juvenile mussels settled on the sediment in early August 2012 and formed a single cohort. The mean shell length of the cohort was greater than 20 mm over the course of one year. The highest daily secondary production was 2.4 g C m⁻² day⁻¹ after the settlement period(from August 31 to October 2, 2012), and accounted for 24% of the total yearly secondary production. Although the yearly secondary production was much higher than that in previous studies, P/B_max (1.7)was comparable to that in earlier studies; P and B_max are secondary production and maximum biomass of A. senhousia, respectively. Thus, the high secondary production in this study was sustained by a large mussel biomass. Maximum secondary production of the mussel population reached approximately one-half of the highest primary production in Ariake Bay. Thus, feeding by this bivalve greatly affects both primary producers and circulation of material in their habitats.