Mesozooplankton community in the Chuuk lagoon of the Federated States of Micronesia

Abstract

Mesozooplankton samples were collected to investigate the spatial distribution in the Chuuk lagoon of the Federated States of Micronesia through three surveys from 2002 to 2004. Average temperature was 28.70°C in August 2002, 30.17°C in October 2003 and 29.18°C in July 2004 at a water depth of 2 m. Average salinity was 33.95 psu in August 2002, 33.56 psu in October 2003 and 33.77 psu in July 2004. Total mesozooplankton consisted of 70 taxa during the study period, among which copepods were the most diverse group. Foraminiferans, radiolarians, copepods and appendicularians, which comprised about 70% of total zooplankton abundance, were important components in the zooplankton community. Within the copepod group, Acartia spp., Centropages spp. and Undinula spp. were dominant in August 2002, Acartia spp., Centropage spp., and Oithona spp. in October 2003, and Acartia spp., Undinula spp., and Oithona spp. in July 2004. Total zooplankton abundance was high around Weno Island, while low in stations located in the northern part of Weno Island. High abundances of appendicularians were found in the southern part of Weno Island as well as around Weno Island. Appendicularians, foraminiferans, radiolarians, Sagitta spp. and immature copepods accounted for most of the distribution pattern of the mesozooplankton community throughout the study area. These results suggest that appendicularians may be potential food items for fish larvae around Weno Island in the Chuuk lagoon states.