鹽寮海域浮游動物群聚組成的時空變異

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2014

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鹽寮灣位處台灣東北角,受到黑潮、東海及南海三大海洋系統影響,生物多樣性高,為龍門核能發電廠所在海域,因此備受關注。本研究時間自2009年至2012年,於鹽寮灣海域進行每季一次浮游動物的豐度、組成及各種環境因子調查,並進行分析研究,以期瞭解影響該海域浮游動物時空分布之變化與因素。結果顯示,本海域表水溫度呈現夏高、冬低的季節性變化,表水鹽度在近岸處較低,且表水冬季營養鹽濃度高、葉綠素濃度低,但夏季呈相反現象。以溫度、鹽度、亞硝酸鹽、硝酸鹽、磷酸鹽、矽酸鹽及葉綠素甲等環境因子之水層積分平均值進行分析,顯示環境因子組成具有年間與季節間差異,但其組成在測站間並無差異存在。研究期間浮游動物豐度介於2.34×103-1.4×107ind./1000m3間,研究前期 (2009~2010年)具有高平均豐度且橈足類比例高,優勢類群以哲水蚤、劍水蚤或無節幼體等橈足類為主;研究後期 (2011~2012年)平均豐度低且橈足類比例低,優勢類群以哲水蚤、尾蟲與夜光蟲為主;推測造成後期橈足類比例下降之原因,可能因夜光蟲大量攝食橈足類卵所導致。同樣的,浮游動物組成具有年間、季節間差異,但無空間差異,其組成變化主要與溫度有關。綜觀本研究認為浮游動物組成除與當地水文環境有關,亦反應出該海域水團的季節性變化,以及可能因聖嬰與反聖嬰現象等大規模海洋環境變動的影響。
The Yan-Liao Bay, northeast coast of Taiwan, has high biodiversity caused by the influence of complexity of water masses including the Kuroshio Waters, East China Sea, and South China Sea. This Bay has also been draw a lot attention since it locates next to the Lungmen Nuclear Power Plant. The purpose of this study was to understand the temporal and spatial variations of zooplankton of this Bay based on seasonal data of abundance and community structure of zooplankton as well as hydrographic variable during 2009 to 2012. Results show that the sea surface temperature was higher in summer and lower in winter. Spatially, the sea surface salinity was lower along the coast. Seasonally, concentrations of nutrients and Chl a were high and low in winter, respectively. However, the inverse pattern was observed in summer. Further analyses show that the averaged values of environment factors integrated over depth were significantly different among years or seasons, but they were not different among stations in the same sampling period. The zooplankton abundance was in the range of 2.34×103-1.4×107ind./1000m3. In 2009 to 2010, the zooplankton abundance and the percentage of copepods were higher than that of 2011 to 2012, and the dominant taxonomic groups were Calanoida, Cyclopoida, and Nauplius. In 2011 to 2012, the dominant taxonomic groups were Calanoida, Appendicularia, and Noctiluca. One of the potential reasons for decreasing percentage of copepods in 2011 to 2012 might be due to grazing of Noctiluca on eggs of copepods. As for zooplankton community structure, it was also significantly different among years or seasons, but it was not different among stations. The changes of zooplankton community structure was more related to temperature variation. Overall, the results suggest that the variation of zooplankton community structure in the Yan-Liao Bay was associated with hydrographic environment influenced by different water masses. It also needs to be noted that the climate events, e.g., El Niño or La Niña, might also have effect on zooplankton community structure, however, longer time scale data is needed to prove it.

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浮游動物, 群聚組成, 橈足類, 水文環境, zooplankton, community structure, copepod, hydrographic factors

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