溫度對台灣東北與西南海岸白帶魚Trichiurus japonicus仔稚成長的影響

Temperature effects on juvenile growth of cutlassfish Trichiurus japonicus between the northeast and southwest coasts of Taiwan

孫瑞雯(Margaret Scholten)

指導教授 ： 王慧瑜

國立臺灣大學/理學院/海洋研究所/碩士(2020年)

https://doi.org/10.6342/NTU202004133

摘要

魚類的成長受到溫度的直接影響，但這過程在仔稚階段依然不明，而因爲仔稚階段對成體階段有關鍵影響，在逐漸惡化的海洋暖化下，解決這知識缺乏是十分急迫的。在台灣海岸的熱帶到亞熱帶的過渡帶，仔稚Trichiurus japonicus 將近整年都有，因此可以用它們來探討溫度對仔稚魚成長的影響。台灣的西南海岸月平均海表溫比東北海岸高，況且西南海岸溫度變異度比較低。在此研究中，我們評估仔稚T. japonicus的成長率是否對溫度有典型的非線性反應。我們預測西南海岸的仔稚成長率會比東北海岸高，且西南海岸的仔稚成長率季節性的變異會比較低。根據從耳石所估計的日齡及體長，我們發現西南海岸的仔稚成長率比東北海岸稍微高一點（分別為1.02 mm/d、0.95 mm/d）。海表溫跟早期仔稚成長的非線性關係只有在西南海岸能觀察到。出生季節對成長變化沒有顯著的影響。我們的數據顯示溫度情況雖然不同，T. japonicus 在東北與西南海岸之間有類似的仔稚成長率。此外，中度的海洋暖化可能不會降低仔稚T. japonicus的成長率，但海表溫過度增加可能會危害西南海岸魚群。

關鍵字

白帶魚 ； 仔稚魚 ； 成長率 ； 耳石 ； 溫度 ； 熱帶 ； 亞熱帶

並列摘要

Fish growth is directly affected by temperature, but relatively little is known about this process during the juvenile stage, which has a crucial influence on adult size and population dynamics. Under ocean warming, it is urgent to address this knowledge gap. Juvenile Trichiurus japonicus are present nearly year-round and span the tropical–subtropical transition zone along the coasts of Taiwan, providing a model system for exploring the effects of temperature on juvenile fish. Monthly mean sea surface temperature (SST) is generally higher and less variable on the tropical southwest coast than on the subtropical northeast coast. In this study, we evaluated if the typical nonlinear response to temperature was present in juvenile T. japonicus growth rates. We predicted that the southwest population would be experiencing a faster but less seasonal variation in juvenile growth rate than the northeast population. Based on individual otolith-derived ages and lengths and monthly mean SST data for Kengfang (northeast coast) and Tsukuan (southwest coast), we found that the overall juvenile growth rate was slightly higher for the southwest than the northeast population (1.02 mm/day and 0.95 mm/day, respectively). Nonlinear relationships between SST and early juvenile growth were only present in the southwest. Birth season did not exert significant effects on growth at either location. Despite different thermal conditions, our data indicate similar juvenile growth rates for T. japonicus between the northeast and southwest coasts of Taiwan. These results suggest that moderate ocean warming may not decrease growth rates for juvenile T. japonicus, but large increases in SST are potentially harmful to the population on the southwest coast.

並列關鍵字

cutlassfish ； juvenile fish ； growth rate ； otolith ； temperature ； tropical ； subtropical

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