Macrofouling community structure in Kanayama Bay, Kii Peninsula (Japan)

Abstract

An investigation on the macrofouling community in Kanayama Bay, Kii Penin­ sula, Japan was undertaken from June 1994 to May 1995 by exposing fiber reinforced plastic (FRP) panels at subsurface and bottom (2.2 m) depths. The composition and abundance of fouling organisms were monitored at monthly intervals. Fortnightly variations in hydrogra­ phic parameters were also noted simultaneously. The fouling community at this bay was a complex assemblage of bryozoans, ascidians, polychaetes and barnacles comprising more than 40 species. The faunal elements exhibited distinct seasonal trends in abundance closely associated with fluctuations in temperature, i.e. maximum abundance was recorded in summer and the reverse in winter. Greater faunal abundance was generally observed on the subsurface panels. Significant depth wise variation in abundance seems to be the result of predation, competition and the effect of residents on recruits. Succession in the community was divided into three stages by dendrogram analysis. First stage was characterized by polychaetes (Protohydroides elegans and Dexiospira foraminosa) on panels from both depths. The encrusting bryozoan, W atersipora subtorquata dominated on the subsurface panels and a mixed dominance of W. subtorquata, barnacles, P. elegans and the ascidian, Polyclinum constellatum, on bottom panels in second stage. Third stage was characterized by a mixed dominance of W. subtorquata, Bugula neritina (an erect bryozoan) and P. constellatum at the subsurface and B. neritina at bottom depths.