Phytoplankton Communities Impacted by Thermal Effluents Off Two Coastal Nuclear Power Plants in Subtropical Areas of Northern Taiwan

Wen-Tseng Lo,Tien-Hsi Fang,Hung-Yen Hsieh,Jian-Hwa Hu,Pei-Kai Hsu

doi:10.3319/tao.2015.09.24.01(oc)

Abstract

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.

Highlights

Phytoplankton are the most important primary producer in most marine food webs
NPP I faces the open ocean in the study area, while NPP II is located within semi-enclosed Kuosheng Bay (Fig. 1)
The highest sea surface temperatures (SSTs) and chlorophyll a (Chl a) concentrations were recorded in summer and the lowest SSTs and Chl a concentrations were recorded in winter and autumn (Figs. 2a, c)

Summary

Introduction

Phytoplankton are the most important primary producer in most marine food webs. Through photosynthesis, phytoplankton convert inorganic compounds into organic compounds using solar energy. The potential impact of thermal discharge from a coastal power plant cooling system on marine organisms and their ecosystem has been studied extensively in the last. The waters off the First (NPP I) and Second (NPP II) Nuclear Power Plants are located at the southern margin of the East China Sea (ECS). In summer the southwesterly monsoon prevails and makes the South China Sea Surface Current (SCSSC) flow northwards through the Taiwan Strait to the southern ECS. In winter the northeasterly monsoon usually drives the cold, low-saline, nutrient-rich China Coastal Current (CCC) southwards along the coast of mainland China into the northern and central Taiwan Strait, where it inhibits the northward intrusion of the SCSSC. The intrusion of the Kuroshio Current to the southern ECS shelf is year-round

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Conclusion