SEASONALITY AND COMMUNITY STRUCTURE OF SUBTIDAL BENTHIC ALGAE FROM DAEDO ISLAND, SOUTHERN KOREA

Seasonal and spatial variations of subtidal algae are described from D aedo Island in southern Korea based on quantitative and qualitative es timates of species occurrence in three habitats: shelf, crest and drop off Maximum species diversity occurred during the winter. Perennial a lgae, including Gracilaria textorii, Ecklonia cava cmd Undaria pinnati fida became particularly abundant in spring. There was a dramatic incr ease in crustose red algae and Cyanobacteria in the summer. As autumn approached the cover of large perennial species decreased. In general, the number of species decreased with increasing depth. The subtidal s helf habitat showed an assemblage of bushy or thin-bladed forms such a s Ulva pertusa, Sargassum thunbergii and Corallina officinalis. Sargas sum horneri, S. confusum, Undaria pinnatifida and Mayagropsis myagroid es had high cover in the crest habitat. Gracilaria textorii and Ecklon ia cava occurred only on the crest and drop off habitats. Sampling at this site in the autumn of 1995 relative to the autumn of 1994 showed about a 50% decline in number of species, with a further decline by th e autumn of 1996. These changes are attributed to increased sediment l oad and scouring resulting from heavy construction in the area (coal-f ired power plant). Despite these perturbations, the basic pattern of s easonal cycling, as modeled with principal component analysis, was mai ntained during the 1995-1996 sampling period.