||This study investigates the tempo-spatial distribution in species composition and abundance of planktonic pteropods in relation to hydrography in the waters around Liu-chiu Yu Island, southwestern Taiwan from February 2006 to October 2007. In total, we recognized 25 pteropod species belonging to 12 genera and six families, with a mean abundance of 7348 ± 994 ind./ 1000m3. The five most dominant species were Limacina inflata, Creseis virgula var. conica, Creseis acicula, Limacina trochiformis and Creseis clava, together they accounted for 78.7 % of the total pteropods.|
The surface sea water temperature, salinity, and phytoplankton concen- tration in the waters around Liu-chiu Yu Island were significantly higher in 2006 than in 2007. Pteropod abundance was higher in spring than in other seasons, and higher in deeper waters than in surface waters. Species number of pteropods was significantly higher in 2007 than in 2006, generally higher in summer and lower in autumn, and higher in deeper waters than in surface waters. Species diversity index of pteropods was generally higher in summer and lower in autumn. Cluster analysis of hydrography included 4 clusters (e.g., 2007 summer, summer and autumn, spring and winter, spring), the 2007 summer cluster was different from other seasons. Pteropod assemblage showed apparent difference between seasons, the variation of pteropod assemblages between stations in spring was higher than other seasons. Linear regression showed that the species number (p < 0.01) and diversity index (p < 0.05) were positively correlated with abundance of fish larvae. Abundance of most dominant species of pteropods was significantly and positively correlated with abundance of fish larvae (e.g., Limacina inflata; Creseis virgula var. conica and Limacina trochiformis) and significantly and negatively correlated with phytoplankton abundance (e.g., Limacina inflata, p < 0.001). In addition to the hydrographic factors, the distribution of pteropods might also be affected by predatory fish larvae and phytoplankton supplement.