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Helgol Mar Res (2009) 63:327337 DOI 10.1007/s10152-009-0162-y
ORIGINAL ARTICLE
Copepod feeding study in the upper layer of the tropical South China Sea
Li-Chun Tseng Hans-Uwe Dahms Qing-Chao Chen Jiang-Shiou Hwang
Received: 26 October 2008 / Revised: 30 April 2009 / Accepted: 11 May 2009 / Published online: 30 May 2009 Springer-Verlag and AWI 2009
Abstract The South China Sea (SCS) is the worlds largest marginal sea being notable for vertical mixing at various scales resulting in a sequence of chemical and biological dynamics in surface waters. We investigated the ingestion, gut content, evacuation and clearance rates of copepods collected from six stations (including a South East Asia Time Series station) along a transect line in the tropical of a SCS cruise during September 27, 1999 to October 2, 1999. The goal of the present study was to understand the feeding ecology of copepods in the upper water layers (05 m) of the northern SCS during autumn. We measured the gut pigment contents of 33 copepod species by the gut uorescence method. The gut chlorophyll a values of most small size copepods (\1 mm) were lower than 1.00 ng Chl a individual-1. The highest gut pigment content was recorded in Scolecithrix danae(7.07 ng Chl a individual-1). The gut pigment contents of 33 copepod species (including 70 samples and 1,290 individuals) estimated is negatively correlated with sea-water temperature (Pearson correlation r = -0.292, P = 0.014) and is positively correlated with the chlorophyll a concentration of ambient waters (Pearson correlation r = 0.243, P = 0.043). Mean gut pigment content, ingestion and clearance rates (from 80 samples and 1,468 individuals) show that larger copepods ([2 mm) had
signicantly higher values than medium sized copepods (12 mm) and smaller sized copepods. The present study shows that the performance of feeding on phytoplankton was variable in different sized copepod groups, suggesting that copepods obtained in the tropical area of the southeastern Taiwan Strait might be opportunistic feeders.
Keywords Copepod Gut content Feeding
Evacuation rate Ingestion rate South China Sea
Introduction
Planktonic copepods are key organisms in aquatic ecosystems, because they are the most important link between the primary productivity of microalgae and the production of many sh species in the oceans (Irigoien et al. 2002; Tseng et al. 2008a)....