경기만에서 Acartia hongi 에 대한 원생동물의 기여

Abstract

To understand the grazing effects of copepod in plankton trophic coupling, grazing experiments were conducted with Acartia hongi, the most dominant and widespread planktonic copepod in Kyeonggi Bay, Yellow Sea. In the laboratory, Acartia hongi were fed on equi-proportional mixtures of the planktonic ciliates (Rimostrombidium oriental, Tintinnopsis angustior and Favella sp.), with the dinoflagellate (Heterocapsa triquetra) or the diatom (Skeletonema costatum and Thalassiosira sp.). In the field, Acartia hongi was fed on natural microplankton assemblage from Kyeonggi Bay. In the laboratory, ingestion rate of A. hongi on planktonic ciliates and phytoplankton increased in proportion as prey concentration increased. When A. hongi were fed ciliate and phytoplankton mixture, ingestion rates of A. hongi on ciliates tends to increase as the ratio of ciliate: phytoplankton carbon increase. In the field, ingestion rates of A. hongi on planktonic protozoa were higher than those of phytoplankton, except phytoplankton blooming periods. The highest ingestion rate of A. hongi on protozoa was observed when autoflagellates dominated. Of the total carbon ingested by A. hongi, plankotnic protozoa contributed from 1.5 to 83% and from 3 to 90% in the laboratory and the field, respectively. This study suggested that protozoa may be an important component of the diet of A. hongi except phytoplankton blooming periods. In addition, the relative composition of diets (i.e. protozoa: phytoplankton) also play an important role for copepod feeding behavior. However, the population dynamics of planktonic protozoa could be significantly influenced by predation of the copepods in Kyeonggi Bay.