This study investigates the distribution in species composition and abundance of pteropods in relation to temperature, salinity, and water masses in the waters of southern Taiwan from February 2004 to October 2005. In total, 25 pteropod species belonging to 13 genera and 6 families were recognized. The mean abundance of pteropods in the study area was 77.3 ¡Ó 32.3 ind. / 100m3. The five most dominant species were Limacina inflata, Creseis virgula var. conica, C. acicula, L. bulimoides, and L. trochiformis, and together they contributed 81.0% of the total number of pteropods, among them, L. inflata occupied 46.7% and was the most dominant species in all seasons. In general , the composition of dominant species of pteropods in each season were similar but ranked different in abundance. The abundance and species number of pteropods changed seasonally. The abundance of pteropods was higher in 2004 than in 2005, and higher in summer than in winter. The species number was lower in autumn(9 ¡Ó 1) and higher in summer(13 ¡Ó 1). The abundance and the species diversity of pteropods were generally higher in the western site(the northern South China Sea) than in the eastern site(Kuroshio Current). In the waters of southern Taiwan, the abundance and diversity index of pteropods and the abundance of the five most dominant species showed no significant correlation with the sea surface temperature and salinity, except the species number that was negatively correlated with salinity.

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 ¡Ó 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.

Recent concern over the effects of ocean acidification upon calcifying organisms in the modern ocean has highlighted the aragonitic shelled thecosomatous pteropods as being at a high risk. Laboratory studies have shown that increased pCO2, leading to decreased pH and low carbonate concentrations, has a negative impact on the ability of pteropods to calcify and maintain their shells. This study presents the micropalaeontological analysis of marine cores from the Caribbean Sea, Mediterranean Sea and Indian Ocean. Pteropods, heteropods and planktic foraminifera were picked from samples to provide palaeoenvironmental data for each core. Determination of pteropod calcification was made using the Limacina Dissolution Index (LDX) and the average shell size of Limacina inflata specimens. Pteropod calcification indices were compared to global ice volume and Vostok atmospheric CO2 concentrations to determine any associations between climate and calcification. Results show that changes in surface ocean carbonate concentrations throughout the Late Pleistocene did affect the calcification of thecosomatous pteropods. These effects can be detected in shells from marine sediments that are located well above the aragonite lysocline and have not undergone post-depositional dissolution. The results of this study confirm the findings of laboratory studies, showing a decrease in calcification during interglacial periods, when surface ocean carbonate concentrations were lower. During glacial periods, calcification was enhanced due to the increased availability of carbonate. This trend was found in all sediments studied, indicating that the response of pteropods to past climate change is of global significance. These results demonstrate that pteropods have been negatively affected by oceanic pH levels relatively higher and changing at a lesser rate than those predicted for the 21st Century. Results also establish the use of pteropods and heteropods in reconstructing surface ocean conditions. The LDX is a fast and appropriate way of determining variations in surface water carbonate saturation. Abundances of key species were also found to constrain palaeotemperatures better than planktic foraminifera, a use which could be further developed.