Potential of a Tintinnid Species, Tintinnidium primitivum, as a Biological Indicator in the Yellow Sea Bottom Cold Water

Tintinnid ciliates, having distributional sensitivity to hydrological changes, have been applied as a useful tool to track the movements of water masses. The Yellow Sea Bottom Cold Water (YSBCW) is one of the most prominent summer oceanographic phenomena in the Yellow Sea. To examine the potential of tint i nnid species as a biological indicator of the bottom cold water, the spatial distributions of the ciliates were investigated in the southeastern Yellow Sea during the summers of 2010 and 2020. A dominant species, Tintinnidium primitivum , was found in the bottom cold waters in both years. The temperature and salinity (T–S) diagram for the dominant species distribution was plotted against the T–S range for the YSBCW at low temperatures between 6 and 12 ℃ and salinity between 32 and 33. A positive relationship was shown between T. primitivum and Gammaproteobacteria distribution and negative relationships with photosynthetic pico- and nano-plankton. Further studies on prey and predator relationships between microbial organisms and T. primitivum are required to understand the unique structure and function of microbial food webs in the YSBCW.