In order to clarify the effects of drifting macrophyte wracks and other materials on benthic macrofaunal community in sandy beaches, species richness and abundance of small benthic macroinvertebrates and sediment conditions (median grain size, sediment moisture, penetration resistance and temperature) were compared among the macrophyte wrack area (MA), drifting material area (DM) and sand area (SA) in the reflective, intermediate and dissipative beach type zones in Fukiagehama Beach, southern Kyusyu island, in May and October, 2015. A total of 4,200 individuals, comprising 12 species (7 families) were collected by quantitative sampling. Talitridae was the most dominant family in species richness and abundance (5 species, 4,453 individuals). In May, Sinorchestia nipponensis was particularly dominant, comprising 41.4% of the total individual number, whereas Excirolana chiltoni was most dominant in October (35.7%). In addition, terrestrial beetles such as Staphylinidae sp. and Hydrophilidae sp. were also collected. Mean species and individual numbers were significantly higher in MA and DM compared to SA in May, suggesting such drifting wracks and materials may be important for Talitridae as food sources and low temperature- and moist-microhabitats. However, such tendencies did not observed in October, when Excirolana chiltoni was dominant. For such an infaunal species, macroalgal wrack and other materials on sediment surfaces may not be a determinant factor affecting their distributions.
sandy beach
macrophyte wrack
drifting material
benthic macrofaunal community
Talitridae