Abstract
Two types of handcorers with different internal diameters (MBARI type corer [MC] ; 7cm, KITAZATO type corer [KC] ; 8cm) were evaluated for their sampling efficiency and sampler bias on meiofauna, based on the samples collected with these corers during dives #820 ∼ 822 of ROV “Hyper Dolphin” at Myojin Knoll, which is about 150km south-southwest of Hachijo Island. It was suggested that the sampling efficiency became worse when overlying water above sediment is leaked from the core samples, regardless of corer type. Meiofauna in the sediments collected with KC showed the “general” vertical distribution pattern; meiofauna were concentrated in the surface layer of the sediments. On the other hand, in the sediments collected with MC, the vertical profiles of meiofauna were rather “uniform”. Furthermore, the community compositions at higher taxonomic level were different from those in the sediments collected with KC. These differences between the corers would be attributed to the differences in core diameter and the degree of disturbance to the edge and surface of the sediment samples. Handcorer-sampling with ROVs or submersibles is essential to the studies on meiofauna around hydrothermal vents. These results of this study, however, suggest that comparing meiofaunal data based on samples collected with different types of handcorers should be done carefully.
