Abundance, distribution and community structure of planktonic copepods in surface waters of a semi-enclosed embayment of Taiwan during transitions of monsoons.

Abstract

In coastal waters around the island of Taiwan, oceanic currents are mainly influenced by the prevailing East Asian monsoonal winds: the northeasterly (NE) monsoon during winter and the southwesterly (SW) monsoon during summer. We identified 101 copepod species (including 27 species solely identified to generic level) belonging to 44 genera and 31 families in Nan-Wan Bay, southern Taiwan. Corycaeus (Onychocorycaeus) catus (15.00%), Oncaea venusta (11.97%), and Clausocalanus furcatus (5.93%) were predominant in Apr., and together they comprised 32.9% of the total number of copepods. Paracalanus parvus (10.08%), Par. aculeatus (9.12%), and Cor. (O.) catus (8.01%) were predominant in Sept. and together contributed to 27.3% of the total copepod abundance. The average copepod abundance was significantly higher in Sept. samples than in Apr. samples. Copepod community parameters showed apparent variations and succession between the 2 sampling months, implying that different species may dominate in different regions with different seasonal distribution patterns. Our results indicate that the copepod assemblages changed with water conditions at the northeastern margin of the South China Sea where water masses of the Kuroshio Current and those of the South China Sea mix.