摘要
在浮游动物生态的研究中,软体动物的研究较其他类群为少。以往的报告,多偏重于地理分布的论述,也有少数涉及垂直分布、相对数量和生物学的研究,此外也有人以浮游软体动物作为水团或海流的指示生物。总的说来,浮游软体动物的生态学研究还不多,而且专论浮游软体动物生态的论文,几乎都取材于北大西洋两岸海域,而有关西太平洋方面的研究成果,迄今尚未见到过。
The area covered by the present investigation is mainly restricted to 28°-34°N in the southern Yellow Sea and the northern East China Sea,of which the area north of 31°N is designated as the northern part and south of that as the southern part in this paper.There are found twenty-six species of Ptcropoda,eight species of Heteropoda,one species of Janthinidae and one species of uncertain systematic position up to now.Among them Creseis aciula Rang,Limacina trochiformis(d’Orbigny),Hyalocylix striata(Rang)and Agadrna stimpsoni A.Adams are relatively dominant.The pelagic Mollusca of the Yellow Sea and of the northern East China Sea in general are not distributed farther than 34°N.The number of species decreases with increasing latitude.The boundary of its area of distribution shifts with the seasons.As a whole,in the west,its boundary shifts shoreward in summer and autumn and retreats to the open sea in winter and spring.In the north,it gradually stretches northward with the increasing of temperature(more strikingly in the months from August to October)and retracts southward with the decreasing of temperature(more strikingly from January to April).More species occur in the months from August to October than in January to April.The length of its occurrence period in the northern part is only about half that in the southern part.The total number of pelagic Mollusca of the northern part is far less than that of the southern part,that of the former being only about 1/10 of the latter.Areas of dense concentration,with more than 100 indiv./100 M^(3),are mainly restricted to south of 31°N and those with more than 500 indiv./100 M^(3) occur generally only in the region about 29°-30°N,123°E,that is,southeast of Chou-Shan.The total number is greater in June to October and lesser in January to April.It may be taken that the occurrence of pelagic Mollusca in this area is chiefly caused by their being carried by the branches of the Kuroshio,the so called Taiwan warm current and Yellow Sea warm current.Water temperature and salinity are the main environmental factors limiting their distribution in this area.The distribution pattern is relatively correlated with temperature and salinity conditions of the lower water layer.It may be due to the fact that in the lower water layer,temperature and salinity are more stable than that in the upper layer.The decrease in number of species with increasing latitude in this area as stated above may be mainly caused by the influence of salinity.The fact that its distribution northward does not in general extend beyond 34°N is probably due to the influence of the cold water mass of the Yellow Sea.The region near 34°N may,therefore,be regarded as.a region of mixing of the Yellow Sea warm current and the cold water mass of the Yellow Sea.The surface current is possibly the carrier of Atlanta rosea Souleyet found occasionally at 35°30′N 121°30′E,off Tsingtao.Cold water species such as Limacina helicina(Phipps)occurring abundantly in the Liman current has never been discovered in this area,so that it may not be taken that the socalled cold water mass of the Yellow Sea communicates with the Liman current all the year round.The data on the quantitative distribution of pelagic Mollusca,in particular of Limacina trochiformis(d’Orbigny),show that the Yellow Sea warm current is stronger in winter than in summer.Several species may serve as good indicators for the Taiwan warm current,among them Creseis acicula Rang is the best one.It is notably impossible to judge the seasonal variation of the strength of this current by the indication of the seasonal variation of this animal in the area under investigation.From its quantitative distribution it may be inferred that the northern limit of the Taiwan warm current roughly near 32°N.
作者
张福绥
ZHANG FU-SUI(Institute of Oceanology,Academia Sinica)
出处
《海洋与湖沼》
1966年第1期13-28,共16页
Oceanologia Et Limnologia Sinica
