Diurnal Cycling in Vertical Distribution of Ichthyoplankton at a Fixed Station off Northwestern Taiwan

臺灣西北外海－固定測站浮游魚類之日週垂直變異

丘臺生(Tai-Sheng Chiu) ； 張光瑢(Kwang-Zong Chang)

《Zoological Studies》 34卷3期 (1995/07) Pp. 183-192

摘要

1994年的五月21-22日，我們在25° 12'N，121° 20'E以固定測站的方式，進行浮游魚類的日週垂直變異之研究。這個固定測站約在淡水河口外的7公里處。現場的溫度和鹽度剖面變化顯示，此處中午時分有水溫分層之現象，且形成躍溫層；其餘時間則分布較均勻。浮游魚類之密度範圍為126至3,167個體/1000立方米。最大密度發生在0100時之底層水，次大者為1,787個體/1000立方米(1900的表層海)。中層水裏三個時段中，浮游魚類之密度約略相等，分別為1,148(0100)，1,288(0700)及1,311(1900)個體/1000立方米。本次實驗共採得5,860個標本，分別屬於82科222個種類。Sardinops melanostictus，佔7.28%為數目最多者。其餘主要為：Callionymus huguenini (5.1 %), Mene maculata (4.7%), Auxis spp. (4.3%)，及Therapon jarbua (3.8%)。聚類分析的結果顯示：浮游魚類群集在三個時間上有區別。此三個時間區別為：午夜(0100)、入夜(1900)及日間(0700及1300)。午夜及入夜有若干程度上的相似，可再歸併，合稱夜間群集。此群集的主要種類為：Leiognathus rivulatus，Setipinna tenuifilis，Ctenotrypauchen microcephalus，gobiid，ophichthid。日間群集則為Scomberoides Iysan，Therapon jarbua，Sardinops melanostictus，Upeneus nensasi, Holocentrus sp., Konosirus punctatus。大部好浮游魚類群集之組成在不同時間上用統計測驗其相關性，結果顯示其間並不相關。

關鍵字

仔稚魚 ； 歧異度 ； 體長組成

並列摘要

The diurnal vertical variation of ichthyoplanktonic abundance was investigated on May 21-22, 1994, at a 65 m deep fixed station (25°12'N, 121°20'E) situated 7 km offshore from the mouth of the Tanshui River, Taiwan. Temperature was stratified at noon but was homogeneously distributed during the remainder of the day. A similar distribution pattern was found also in salinity profiles. The density of ichthyoplankton ranged from 126 to 3167 ind/1000 m^3. The highest density occurred in bottom water at 0100 and a fairly even distribution occurred in mid-water. A total of 5,860 ichthyoplankton specimens was collected and 222 species, or species groups belonging to 82 families, were identified. Sardinops melanostictus was the most abundant, making up 7.2% of the total catch. The next four most abundant species were Callionymus huguenini (5.1%), Mene maculata (4.7%), Auxis spp. (4.3%) and Therapon jarbua (3.8%). The dendrogram from the clustering method of unweighted pair-group method using arithmetic averages (UPGMA) exhibited three assemblages: mid-night (0100), afterdark (1900) and daytime (0700 and 1300). The former two assemblages were grouped as the nighttime assemblage because they were similar, and the dominant species were Leiognathus rivulatus, Setipinna tenuifilis, Ctenotrypauchen microcephalus, gobiid and ophichthid. The daytime assemblage was primarily composed of Scomberoides Iysan, Therapon jarbua, Sardinops melanostictus, Upeneus bensasi, and Holocentrus sp.

並列關鍵字

Larval fish ； Diversity ； Length frequency