莱州湾夏季浮游桡足类的摄食研究

COPEPODS FEEDING ACTIVITIES IN THE LAIZHOUWAN BAY, BOHAI SEA, IN SUMMER

于１９９７年７月大潮（１９－２４日）和小潮（２６－３０日）期间在莱州湾对不同大小桡足类自然群体（大型：＞５００ｍｍ，小型：２００－５００ｍｍ）的分布及肠道色素含量进行了现场测定，并在一个４８ｈ连续观测站（Ａ４）进行了肠道排空率和摄食节律实验。结果表明，浮游动物肠道色素含量随个体的增大而增加，大型桡足类存在着一定的昼夜摄食节律，摄食高峰出现在夜间，小型桡足类摄食节律不明显。Ａ４站测得的桡足类摄食率结果表明，桡足类群体的日摄食量占初级生产力的２０．８１％－９８．３５％，占浮游植物现存量的２．５３％－６．３６％，对浮游植物的生长有一定的限制作用，小型桡足类是浮游动物摄食浮游植物的主要类群，占桡足类群体总摄食量的８４．０％－８７．９％。

Copepods distribution and gut pigment contents were studied during two cruses in the Laizhouwan: spring tide Cruise, 19-24 and neap tide cruse 26-30 July 1997. In addition to routine measurements (CTD, nutrients, chlorophyll, primacy production, copepods abundance, etc.), observations and experiments on copepods gut pigment contents, diurnal feeding rhythms and gut evacuation rites were conducted. Copepod assemblages were divided into two size groups: large size group (>500mm) and small size group (200-500mm) by the body size approach in the study. The purpose of this work is to understand better copepods feeding and the grazing impact on phytoplankton by the different size groups. The result showed that the small copepods (mainly Paracalanus parvus, Acartia bifilosa, Oithona similis etc.) dominated numerically and accounted for > 90% of the copepods community. The large copepods (mainly Calanus sinicus, Acartia pacific) were less abundant and decreased in number with increasing temperature. The mean level of gut pigments increased with increasing size, but relatively low. The distribution pattern of gut pigments implied that grazing of copepods was affected by the same environmental factors (food availability, temperature, etc.). The large size group of copepod assemblages performed feeding rhythms with maximum level at midnight. No apparent feeding rhythms was found in the small groups. The daily grazing rate of the copepod population on phytoplankton at A4 was 20.81%-98.35% of the primary production and 2.53%-6.36% of the phytoplankton standing stock. The consumption of phytoplankton was mainly caused by grazing of the small size group of copepods (84.0%-87.9%).