| Summary: | 碩士 === 國立臺灣海洋大學 === 環境生物與漁業科學學系 === 99 === This study was carried out in three cruise in June , December 2009 and December 2010 on the board of the “ Ocean Research II ” for understanding the factual distribution of the fish larvae assemblage during the winter and summer time in the Southern East China Sea.
The range of water temperature was varied from 17.08℃ to 27.86℃ in June 2009 , from 14.64℃ to 22.74℃ in December 2009, and from 16.21℃ to 23.60℃ in December 2010. The range of water salinity was from 32.39psu to 34.63psu in June 2009, from 30.08psu to 34.64psu in December 2009, and from 29.92psu to 34.66psu in December 2010.
Total numbers of 2,317 larvae were collected from 27 stations, and 145 taxa contributing to 74 families were identified. The most dominant species in summer were Decapterus spp. (26.7%), SCIAENIDAE spp. (11.3%), and Auxis spp. (6.7%). The most dominant species in winter 2009 were Trichiurus lepturus (17.1%), Gonostoma gracile (12.4%), and Lampadena spp. (8.6%), and the most dominant species of winter in 2010 were Trichiurus lepturus (12.3%), Bregmaceros spp. (7.2%), and Gonostoma gracile (5.1%). In addition, the abundances of larval fish were 1279.57 ± 380.78 inds./1000m3, higher during summer than 234.56 ± 261.76 inds./1000m3 and 224.42 ± 216.71 inds./1000m3 during winter. By the ANOVA test, the species composition and abundances of larval fish in both season and mesh size were significant difference(p<0.05).
For the diversity, Shannon diversity and richness index were higher in summer, while evenness index were higher in winter. For the difference in the mesh size, Shannon diversity and richness index were highest in the mesh of 330μm, and evenness index were highest in the mesh of 1000μm.
All the stations could be divided into summer and winter group. Four groups(A~D) were divided by the two-way cluster analysis. The A group species were included Schindleria spp., Trichiurus lepturus and Bregmaceros spp. while is dominated in winter, but fewer in summer. The B and D group species dominated in winter and summer, respectively were included Lampadena spp., Myctophum asperum and Gonostoma gracile, and SCIAENIDAE spp., Decapterus spp., Cynoglossus joyneri and Auxis spp.. The C group species were widely distributed included SCORPAENIDAE spp., Diaphus A group, MUGILIDAE spp. and Benthosema pterotum in summer and winter.
It suggested that the spatial distribution of larval fish in summer was widely distributed, while it was aggregated and possibly influenced by Kuroshio current in winter.
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