Lo, W-T., Purcell, J. E., Hung, J-J., Su, H-M., and Hsu, P-K. 2008. Enhancement of jellyfish (Aurelia aurita) populations by extensive aquaculture rafts in a coastal lagoon in Taiwan. – ICES Journal of Marine Science, 65: 453–461. Blooms of the moon jellyfish, Aurelia aurita, often occur in coastal waters that are heavily affected by human construction, such as harbours. Tapong Bay is a hypertrophic lagoon in southwestern Taiwan that was studied between August 1999 and September 2004. The removal of extensive oyster-culture rafts in June 2002 provided a “natural” experiment to examine the effects of aquaculture on processes and communities in the lagoon. The removal caused many changes in the ecosystem, including increases in flushing, light penetration, dissolved oxygen, salinity, chlorophyll a, primary production, and zooplankton, but decreases in nutrients, periphyton, and dramatically reduced populations of bivalves, zooplanktivorous fish, and jellyfish (A. aurita). We conclude that environmental and trophic conditions were favourable for jellyfish throughout the study period. Therefore, we believe that aquaculture rafts enhanced jellyfish populations by three probable mechanisms: the rafts provided substrate and shading for the larval settlement and polyp colony formation, and the rafts restricted water exchange in the lagoon. Aquaculture is increasing rapidly in Asia, and the problems associated with jellyfish may also increase.

The aim of this study was to investigate the species composition and distribution of fish larvae in relation to hydrographic conditions in the waters surrounding Taiwan Island (TI) in February 2003. In total, 242 kinds of fish larvae belonging to 127 genera and 75 families were recognized. Among these, 109 taxa were identified to the family or genus level, others to the species level. The 12 predominant types, which constituted 71% of the total fish larvae, were Engraulis japonica, Scomber sp., Diaphus spp., Benthosema pterotum, Carangoides ferdau, Embolichthys mitsukurii, Maurolicus sp., unidentified Myctophidae, Gonostoma gracile, Trichiurus lepturus, unidentified Gobiidae, and Myctophum asperum. The distribution of fish larvae showed a clear association with water masses around TI, with higher abundances and lower species richness northwest of TI where the China Coastal Current prevails, and lower abundances and higher species diversity east of TI where the Kuroshio Current dominates. Cluster analysis distinguished three station groups and four species groups, and the distribution patterns of fish larvae also corresponded to hydrographic conditions. The total abundances of fish larvae and eight of the 12 predominant taxa showed significant and positive correlations with zooplankton abundance, which suggests that food source might be a key factor determining the abundance and distribution of fish larvae during the winter.

This study investigates the seasonal and spatial differences in phytoplankton communities in the coastal waters off two nuclear power plants in northern Taiwan in 2009. We identified 144 phytoplankton taxa in our samples, including 127 diatoms, 16 dinoflagellates, and one cyanobacteria. Four diatoms, namely, Thalassionema nitzschioides (T. nitzschioides), Pseudo-nitzschia delicatissima (P. delicatissima), Paralia sulcate (P. sulcata), and Chaetoceros curvisetus (C. curvisetus) and one dinoflagellate Prorocentrum micans (P. micans) were predominant during the study period. Clear seasonal and spatial differences in phytoplankton abundance and species composition were evident in the study area. Generally, a higher mean phytoplankton abundance was observed in the waters off the First Nuclear Power Plant (NPP I) than at the Second Nuclear Power Plant (NPP II). The phytoplankton abundance was usually high in the coastal waters during warm periods and in the offshore waters in winter. The phytoplankton species composition was different in the NPP intake and outlet. An abundant phytoplankton increase in the outlet was frequently detected, probably due to the difference in phytoplankton species suitability to thermal stress. Our results suggest that thermal discharge may affect the phytoplankton communities by altering its species composition within a restricted area close to the NPP. This study provides basic knowledge on phytoplankton distribution patterns, essential information required to further understand the ecological impact caused by thermal effluents.

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