Zooplankton from the inshore waters of Christmas Island (Indian Ocean) with reference to larvae of the red land crab, Gecarcoidea natalis

摘要

The red land crab, Gecarcoidea natalis, which is endemic to Christmas Island in the Indian Ocean, has an obligate marine larval phase. Surface plankton tows, using a 500 μm mesh net, were completed monthly at three sites on the north coast of Christmas Island to determine the composition, abundance and seasonal variation of the macro-zooplankton and detect the presence of red crab zoea larvae. The highest plankton concentrations were found at the end of the southeast monsoon period and, at all other times of the year, plankton settled volumes were very low, typically <0.1 ml/m~3 of water sampled. Despite rearing red crab zoea obtained from spawning females, it was not possible to definitively identify them from among the wide diversity of brachyuran zoea found in the plankton samples.