MEPS 274:99-122 (2004)  -  doi:10.3354/meps274099

ABSTRACT: Copepod community structure and productivity was investigated off the west coast of Phuket, Thailand, along transects from the shallow coastal water across the shelf break to the deep oceanic stations in the Andaman Sea. Cruises were conducted during the 2 monsoons, the calm and dry NE monsoon (November to March), and the stormy and wet SW monsoon (May to September). The copepod community was sampled with a 50 µm net to include the smallest species characteristic of oligotrophic waters. The copepod community was characterized by high species diversity; high-resolution analysis of species composition at the coast, the shelf break and the deep off shore stations, however, revealed no differences in species composition between areas. Small copepods, mainly cyclopoids and poecilostomatoids (dominated by Oithona spp. and Oncaea spp.), made up half of the number and ca. 25% of the copepod biomass. Despite the presence of highly dynamic internal waves at the shelf break, no response in either copepod biomass or potential prey biomass (phytoplankton and protozooplankton) was observed at the shelf break. Egg production rates of 5 calanoid species (Acrocalanus gibber, Acartia australis, Centropages furcatus, Temora discaudata, Euchaeta marinella), 1 cyclopoid (Oithona plumifera) and 1 poecilostomatoid (Oncaea venusta) were measured and compared along transects and between seasons. No spatial or seasonal patterns in biomass or egg production rates of the investigated copepods were observed. Carbon flow budgets for the 3 areas investigated suggest that the production of the copepod community in this picoplankton-dominated environment is strongly dependent on protozooplankton as prey to fuel the measured egg production rates.

KEY WORDS: Tropical copepod community · Calanoids · Cyclopoids · Egg production · Secondary production · Andaman Sea