Characteristic distributions of a planktonic ciliate group, tintinnids, from the frontal zone in the South Sea of Korea and an indicative species, Metacylis sp., of Yangtze River inflows

Abstract

As the frontal zone of coastal waters has potentiality of high primary productivity, planktonic predators including tintinnids can be flourished in the zone. Seasonality of tintinnid distribution was investigated via the frontal zone survey in the South Sea for 2016 and 2017. Higher diversity of tintinnid species were recorded in summer (August 2016). Vertical profile of tintinnid distribution in the frontal zone was matched well with the distribution of its prey sources of chlorophyll-a and bacteria. High abundance of a neritic species, Tintinnopsis beroidea, was detected in the surface chlorophyll maximum (SCM) layer at A-5 station of a western frontal zone. A patch distribution of Metacylis sp. was found in the water mass of high temperature and low salinity at the B-3 station of an eastern frontal zone, which coincided with the bacterial distribution. In particular, Metacylis sp. occurrence was traced through the long-term monitoring in the Jangmok Bay. The species was detected in the summer when the significant inflow events of the Yangtze River water was extended to the southern coastal waters of Korea. The result implies that Metacylis sp. can be an indicative species for tracking Yangtze River inflows. Additionally, lorica morphology and molecular analysis of Metacylis sp. are provided as a supporting data for a new species candidate. in the South Sea for 2016 and 2017. Higher diversity of tintinnid species were recorded in summer (August 2016). Vertical profile of tintinnid distribution in the frontal zone was matched well with the distribution of its prey sources of chlorophyll-a and bacteria. High abundance of a neritic species, Tintinnopsis beroidea, was detected in the surface chlorophyll maximum (SCM) layer at A-5 station of a western frontal zone. A patch distribution of Metacylis sp. was found in the water mass of high temperature and low salinity at the B-3 station of an eastern frontal zone, which coincided with the bacterial distribution. In particular, Metacylis sp. occurrence was traced through the long-term monitoring in the Jangmok Bay. The species was detected in the summer when the significant inflow events of the Yangtze River water was extended to the southern coastal waters of Korea. The result implies that Metacylis sp. can be an indicative species for tracking Yangtze River inflows. Additionally, lorica morphology and molecular analysis of Metacylis sp. are provided as a supporting data for a new species candidate.