Seasonal changes in biomass of macrophytes stranded on Yoro Beach along a sargassacean forest in Wakasa Bay,Sea of Japan

ABSTRACT:   Macrophytes stranded on a beach provide food and habitat for many kinds of animals and play important roles in coastal ecosystems. Macrophytes stranded on a sampling beach (56 m long) along a sargassacean forest (400 m long and 88 m wide) were collected every 10 days from late April 2003 to late May 2004. The weight of macrophytes stranded per meter of beach amounted to 1733 g dry wt/m per year. Sargassacean plants were dominant and constituted 72.9% (1263 g dry wt/m per year) of whole stranded macrophytes. Large numbers of macrophytes were stranded just after heavy winter storms and the maximum weight of stranded macrophytes in winter was 407 g dry wt/m. Stranded macrophytes also increased in May to July; the deterioration period of sargassacean species in this region, and the maximum weight in this period was 233 g dry wt/m. The number of sargassacean plants stranded with holdfast increased only in winter. These results suggest that winter storms have an important role in stranding sargassacean plants at Yoro Beach.