夏季胶州湾微型浮游动物摄食初步研究

2002年6月至7月间对胶州湾内、外和港口3个典型站位进行了微型浮游动物对浮游植物的摄食研究．按陆基半现场方式进行了4次稀释法实验，对湾外相同的站位进行了两次实验，对湾内和港口各进行了一次实验，获取了研究站位浮游植物和微型浮游动物种类、丰度、体积转换浮游植物碳含量、碳／叶绿素比率、浮游植物净生长率、微型浮游动物摄食率、对潜在初级生产力的摄食压力、对浮游植物现存量的摄食压力以及碳摄食通量等参数．湾外和湾内站位的浮游植物组成相似，优势种为新月柱鞘藻(Cylindrotheca closterium)和中肋骨条藻(Skeletonema costatum)，港口浮游植物优势种类为中肋骨条藻、浮动湾角藻(Eucampia zodiacus)和旋链角毛藻(Chaetoceros curvisetus)．湾外微型浮游动物的优势种为百乐拟铃虫(Tintinnopsis beroidea)，而在湾内为百乐拟铃虫和急游虫(Strombidium sp．)，港口主要为急游虫，也有少数的百乐拟铃虫．微型浮游动物对浮游植物的摄食率和对潜在初级生产力的摄食压力，在湾内最高，其次在湾外，港口最低．微型浮游动物对浮游植物的摄食率，在湾外，分别为0．96和1．20d^-1，在湾内为1．33d^-1，在港口为0．36d^-1．微型浮游动物对潜在初级生产力的摄食压力，在湾外，分别为74％和84％，在湾内为93％，在港口为53％．微型浮游动物的碳摄食通量在港口最高达到281mgC·m^-3·d^-1，在湾内为102mgC·m^-3·d^-1，在湾外最低范围在31～49mgC·m^-3·d^-1．浮游植物的细胞大小和两种微型浮游动物的摄食习性的不同是造成研究站位微型浮游动物摄食率和摄食压力不同的主要原因．同世界其它内湾相比，胶州湾微型浮游动物的摄食压力处于中等水平。

Microzooplankton grazing on phytoplankton in summer in the Jiaozhou Bay, China

With dilution method, this paper studied the microzooplankton grazing on phytoplankton inside, outside and in a harbor area of the Jiaozhou Bay during June and July 2002. The dominant phytoplankton species outside and inside the bay were Cylindrotheca closterium and Skeletonema costatum, while the samples in the harbor had Skeletonema costatum, Eucampia zodiacus, and Chaetoceros curvisetus as the dominant species. The dominant microzooplankton species outside and inside the Jiaozhou Bay were Tintinnopsis beroidea and unidentified Strombidium sp., while in the harbor, Strombidium sp. was the predominant microzooplankton species coexisted with few T. beroidea. The grazing rate of microzooplankton was 0.96 and 1.20 d(-1) outside the bay, 1.33 d(-1) inside the bay, and 0.36 d(-1) in the harbor. The grazing rates of microzooplankton and the consumption percentages of potential primary production increased in turn from harbor area, outside the bay, to inside the bay. They were 74% and 84% outside the bay, 93% inside the bay, and 53% in the harbor. The ingestion rate of phytoplankton carbon by microzooplankton was the highest in the harbor, with a value of 281 mgC x m(-3) x d(-1), the next was inside the bay, with a value of 102 mgC x m(-3) x d(-1), and the lowest was outside the bay, ranged from 31 to 49 mgC x m(-3) x d(-1). It seems that the phytoplankton community size structure and grazing behaviors of dominant microzooplankton species are the causes for these grazing differences. Compared with the similar studies in other bays around the world, the grazing pressure of microzooplankton in the Jiaozhou Bay is at the middle levels.