The Inter-annual Variability of Microplankton Community Structures in the Coastal Waters of the Gulf of Thailand

Abstract

The inter-annual variations of the microplankton community structures were studied in the coastal waters of the Gulf of Thailand during June 2012 to March 2013. Since phototrophs are basis of marine pelagic food webs, while heterotrophs are major consumers of primary productions and are also intermediaries between primary producers and higher consumers, the microplankton taxonomic classify was made with respect to the trophic structures. The samples were collected using a filtering technique and a 20 μm plankton mesh size. The results showed that centric diatom phototrophs dominated the waters, while the major heterotrophs were loricate ciliates and copepod nauplii. The changing hydrological variations affected the species compositions and abundances of microplankton, which showed the highest values
during the post Southwest monsoon season in December 2012. Furthermore, the low diversity index values were recorded during the study period, implying that the area exhibited less diverse food items. This might in turn lead to short and simple food web, and also loose pelagic trophic structure.