Temporal and spatial occurrence of aloricate ciliates parasitized by dinoflagellates in Korean coastal and offshore waters

Abstract

Planktonic ciliates have long been viewed as important prey of mesozooplankton, with predation by zooplankton generally considered the main grazer control of ciliate populations. However, parasitism of aloricate ciliates by parasitic dinoflagellates was recently recorded in Masan Bay, Korea. It was suggested that high infection levels may contribute to top-down control of ciliate host-species. This study was carried out to clarify the temporal and spatial distribution of infected aloricate ciliates through extensive surveys in offshore waters (Kuroshio Current), as well as nearshore waters (Busan coastal area, Ulsan Bay, Jinhae Bay, and Goseong Bay), of southern Korea. The number of southern coastal stations with infected ciliates was highest in November. The appearance of infected ciliates in the Kuroshio Current during May implies possible allochthonous intrusion of parasitic dinoflagellates into Korean coastal waters. Ongoing monitoring of infected ciliates may contribute to understanding temporal and spatial relationships between host and parasite populations in nearshore and offshore waters of Korea.agellates was recently recorded in Masan Bay, Korea. It was suggested that high infection levels may contribute to top-down control of ciliate host-species. This study was carried out to clarify the temporal and spatial distribution of infected aloricate ciliates through extensive surveys in offshore waters (Kuroshio Current), as well as nearshore waters (Busan coastal area, Ulsan Bay, Jinhae Bay, and Goseong Bay), of southern Korea. The number of southern coastal stations with infected ciliates was highest in November. The appearance of infected ciliates in the Kuroshio Current during May implies possible allochthonous intrusion of parasitic dinoflagellates into Korean coastal waters. Ongoing monitoring of infected ciliates may contribute to understanding temporal and spatial relationships between host and parasite populations in nearshore and offshore waters of Korea.