Zoological Studies

Vol. 47 No. 2, 2008

The Coupling of Copepod Assemblages and Hydrography in a Eutrophic Lagoon in Taiwan: Seasonal and Spatial Variations

Pei-Kai Hsu1, Wen-Tseng Lo1,*, and Chang-tai Shih1,2,3

1Department of Marine Biotechnology and Resources, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
2Department of Environmental Biology and Fisheries Science, National Taiwan Ocean University, Keelung 202, Taiwan
3Canadian Museum of Nature, Ottawa,  K1P 6P4, Canada

Pei-Kai Hsu, Wen-Tseng Lo, and Chang-tai Shih (2008) Seasonal and spatial variations in the species composition and abundances of copepods in relation to hydrographic conditions in Tapong Bay, a tropical eutrophic lagoon in southwestern Taiwan, were investigated bimonthly in 2003.  The water temperature, salinity, and chlorophyll a (Chl a) of the bay showed apparent seasonal changes, with cold, saline, low-Chl a water in the dry winter (Dec. and Feb.) in contrast to warm, fresh, and high-Chl a water in the rainy summer (June and Aug.).  In all, 84 copepod species belonging to 15 families and 23 genera were identified.  Parvocalanus crassirostris, Bestiolina amoyensis, Oithona oculata, Acartia sinjiensis, Acartia sp., and Temora turbinata were predominant, and together they comprised 86.4% of the total number of copepods.  Although copepod parameters showed no significant quantitative differences among seasons or sites, they showed apparent variations and succession in some months and at some stations, implying that different species may dominate different regions with different seasonal distribution patterns.  These variations in copepod assemblages can also be seen from results of a principal component analysis of station groups and cluster analysis of species groups.  The copepod assemblage showed larger variations in winter and in the inner bay than in other seasons and regions, and each station group displayed a distinctive distribution pattern.  Our results suggest that even though removal of oyster culture racks in 2002 resulted in an apparent increase in zooplankton number, multiple environmental variables, such as food sources, wastewater discharges, tidal flushing, and climate, are still interactively influencing the distribution patterns of copepods as they were previously shown to be doing in the bay.

Key words: Copepods, Distribution, Human impact, Lagoon.

*Correspondence: E-mail:lowen@mail.nsysu.edu.tw