Community analysis of reef habitats in the Marshall Islands

Between summer 2001 and 2003 three scientific expeditions were organized in four different atolls of the Marshall Islands as part of a research project aiming to assess marine resources in the whole country. Two atolls were explored in 2003, Rongelap in the north and Mili in the south of the country. Information on corals and fish abundances is presented here for a description of the coral reef communities and comparison of the ecological differences between the two locations. Clear variability of community composition inside an atoll is already evident from the first in situ observation, outer ocean sites being very different from lagoonal locations for both coral and fish composition. At a more detailed scale, the surveyed sites show differences in community composition, supported both through an a posteriori study based on their geographical location and exposure to the main current and surface wind, as well as through an CI priori multivariate analysis of the community. However. this latter analysis does not show a clear relationship between the fish species composition and the substrate or coral species composition. This is most probably due to other effects than just habitat and food availability in the constitution of a complex community such the one found in coral reefs.