Sessile Invertebrate Colonization of a Coral Patch Reef: A Study of Two Reefs in Kaneohe Bay, Hawaii

Abstract

Marine invertebrate colonization for a complete annual cycle was examined on two coral patch reefs in Kaneohe Bay, Oahu, Hawaii. Polyvinyl chloride panels provided the substratum for settlement and their placement on the reefs was along windward to leeward (upstream to downstream) transects. Counts of individual organisms and area covered by colonies provided data for site by site and inter-reef comparisons of temporal and spatial colonization trends. Over 80% of the total invertebrate settlements could be ascribed to five taxonomic groups: oysters, barnacles, serpulid worms, bryozoans, and tunicates. The patterns of colonization exhibited by these five groups are analyzed and discussed in detail. The greatest numbers of new settlements consistently occurred at the shallow windward site of each reef, whereas the least amount of colonization took place in the middle of the study reefs. These colonization phenomena are discussed with respect to the influence of various physical and biological factors. Five months into the study, all of the fishes were removed from the smaller of the two patch reefs, providing at least temporarily, a means of examining the effects of fish on invertebrate colonization. Visual transects were used prior to and after fish removal to assess the resident fish population. Due to the rapid recolonization of the reef, particularly by dominant herbivores, major effects on invertebrate colonization patterns were not detected.