东海毛颚动物夏季垂直分布

VERTICAL DISTRIBUTION OF CHAETOGNATHS IN THE EAST CHINA SEA IN SUMMER OF 1978

本文材料取自范围为123°—129°E,26°30′—32°30′N的东海。主要在水深超过80米的测站进行垂直分层采集。采集层次为0—50米,50—100米,100—250米,250—500米,500—1000米,1000米—底。网具用附闭锬装置的大型浮游生物网。资料的整理系沿200米等深线划分为两部分(A区和B区)进行计算和分析。经鉴定的毛腭类计4属21种,它他大多数分布子100米上层,数量和种类随着深度的增加而减少。优势种肥胖箭虫分布于0—250米,少数能分布更深,但数量集中于100米上层。2个近似种——海龙箭虫与百陶箭虫的垂直分布有所不同,前者几乎只在A区,主要在50—100米;后者A、B区皆有,50米上层居多。微箭虫的分布有避开表面的趋势。第一次采到大头箭虫、拟漂移箭虫和钩剌真(?)虫等个别标本。钩剌真(?)虫是冷水种,分布深度随纬度而异。

The study was conducted in the East China Sea,located about 123°-129°E, 26°30'N-32°30'N. Vertical hauls were mainly made at depths greater than 80 meters and samples were taken through a water column at layers 0-50,50-100. 100-250,250-500,500-1,000, 1,000-bottom.A Nansentype conical net with closing mechanism was used. For convenience of notation, the area shallower than 200m and deeper than 200m will be referred to as the area "A" and "B" respectively in this paper.Chaetognaths were identified and counted,21 species of 4 genera of maturing and matured ones were found. Most of them appeared to be more abundant in the upper 100m and decreased rapidly with increasing depth.Sagitta enflata-the most common and abundant species,mostly found between 0-250m with some caught in the lower strata, extending into deeper waters even down to 500m.However,most concentrated layer was the upper 100m.There were differences found in the vertical distributional patterns of twoallied species--Sagitta nagae and Sagitta bedoti. The former inhabited almostonly area "A",with its maximum occurrence between the 50 and the 100m level, while the latter was distributed from area "A" to "B" and had its maximum in the uppermost 50m.Sagitta minima appeared to avoid the surface and lived fairly deep in the water column.Single specimens of Sagitta macrocephala Power, Sagitta zetesios Power,and Eukrohnia hamata(Mbb'ms} were found for the first time in the present investigation. Among them E hamata is a bipolar species which changes its distribution in depth with latitude.