Microplankton (including dinoflagellate and foraminifera) in the South China Sea, Area I: Gulf of Thailand and Peninsular Malaysia

Abstract

Joint collaborative research surveys in the Gulf of Thailand and the South China Sea around the east coast of Peninsular Malaysia during the pre northeast monsoon (4 September - 4 October, 1995) and the post northeast monsoon (24 April - 17 May, 1996) periods were carried out on board the MV SEAFDEC. The microplankton from the sampling stations consisted of more than 205 taxa consisting predominantly of blue green algae (2 species), diatoms (> 120 species), dinoflagellates (> 80 species) and microzooplankton (> 30 groups). The dominant diatom species comprised of Chaetoceros lorenzianum,C. coastatum, Thalassionema frauenfeldii, Skeletonema costatum, Pleurosigma elongatum, Bacteriastrum comosun, Bacillaria paxillifera, Coscinodiscus jonesianus and Rhizosolenia calcar-avis. The genera Chaetoceros, Rhizosolenia, Coscinodiscus, Bacteriastrum and Ceratium were found to contain a wide range of species. Skeletonema bloom (1.12 x 106/m³; 47% of the total cell count) occurred around the Johore waters of the South China Sea. Dinoflagellate was also present during the premonsoon period, especially in offshore waters of the Gulf of Thailand and Terengganu nearshore waters of the South China Sea. The microzooplankton consisted of more than 30 species dominated by copepod nauplii while the foraminifera consisted mainly of the Globigerina species. The diversity index (H) and evenness index (J) values were usually high at stations near to the coast.