Community structure of demersal fishes from continental shelf to lower continental slope around Taiwan

• Main Authors: Chun Liao, 廖竣
• Other Authors: 蕭仁傑
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/48403065915190782584

碩士 === 國立臺灣大學 === 漁業科學研究所 === 104 === Community structure of demersal fish around Taiwan were examined from bottom trawl surveys between 2000 and 2014. A total of 888 fish species were recorded from 196 sampling sites extending from 10 to 2580-m depth and spanning the northeast (NE) and southwest (SW) shelves and slopes, as well as the western (W) shelf off the island of Taiwan. Cluster analysis and multi-dimensional scaling (MDS) show that the fish fauna changes were gradual and continum along the depth gradient. On the continental shelf, the demersal fish can be separated into W and NE-SW assemblages, with the W assemblage being further divided into several significant subgroups. Along the shelves and slopes, the fish assemblage compositions were significantly different between the NE and SW regions, but the difference became smaller with depths.The assemblage composition was significantly correlated with depth, temperature, roughness, mean primary production and particlulate organic carbon flux (POC flux) on the shelves, where the Lizardfish (Saurida wanieso) most frequently occurred on the shelf north of the Penghu island and Dragonet (Callionymus planus) characterized (by occurrence) the shelf south of the Penghu island. At upper bathyal depths (201 – 1000 m), the assemblage composition was significantly correlated with depth, roughness, mean primary production, seasonal variation of mean primary production and POC flux. The SW upper bathyal zone was characterized by demersal rattail fish (macrouridae) but the NE characterized by mesoplagic lantem fish (myctophidae). The frequent occurrence of lantemfish fish in the NE upper bathyal zone is presumably related to upwelling and abundant zooplankton in the region, in which the environmental conditions may favor the lantemfish with strong vertical-migration ability to optimize their foraging strategy. At the lower bathyal depths (>1000 m), the assemblage composition was siginificantly correlated with depth, temperature, roughness, mean primary production, seasonal variation of primary production and POC flux; however, delining food supplies and the bottom terrain characteristic appears to be the main controls of the assemblage composition. The brislemouths (gonostomatidae) were the most frequently occurred fish species, suggesting that the habitats lokely become more similar between the NE and SW lower bathyal zones. In conclusion, the delineation of demersal fish assemblages off Taiwan were influenced by large-scale environmental forcing (e.g. depth and water masses) but the small-scale habitat heterogeneity may also contribute to small-scale regional variations (e.g. bottom type and terrain roughness).