Diversity in Intertidal Habitats: An Assessment of the Marine Algae of Select High Islands in the Hawaiian Archipelago

Abstract

Quantitative and qualitative sampling of intertidal algal assemblages on a limestone bench (O'ahu) and basalt benches (O'ahu and Hawai'i) resulted in enumeration of more than 100 species of macrophytic and turf species on O'ahu and over 60 species of primarily turf algae on Hawai'i. These assemblages are diverse and of a mosaic type and represent subcosmopolitan species, pantropical species, West Pacific species, and apparent endemic species. The algal community on Hawai'i shares 40 to 75% similarity with O'ahu populations that in one case shared only 66% similarity with adjacent sites for the same substrate type. It is suggested that the differences in species distributions are associated with age-related substrate effects and possibly settlement shadow effects.