Tintinnid annual occurrence pattern in Port Shelter, northern South China Sea

Abstract Biogeography of neritic tintinnid is rarely studied although there were a lot of reports of species occurrence along the coastal areas around the world oceans. According to the temperature tolerance range and environmental temperature, plankton species would change its annual occurrence pattern in its distribution latitudes. Tintinnid annual occurrence pattern was monitored in a subtropical coastal site of northern South China Sea and estimated their geographic distribution of different species. Temperature ranged in 17.89–32.31°C with the highest value in August. The whole year period was divided into cool period (<26°C) and warm period (>26°C) with some fluctuation in salinity. According to the annual occurrence pattern, two species groups could be defined: cool group (8 species) and warm group (10 species). Each group was further divided into periodic species and year-round species. We summarized several models of annual occurrence patterns and estimated optimal temperature of the species. Most of warm species occurred simultaneously ~26°C in May, which is recommended to be monitored as tintinnid phenological event. Our results provided valuable insights into the annual occurrence patterns and biogeography of neritic tintinnids in the low latitude coast, further contributing to the comprehensive understanding of coastal microzooplankton phenology in different latitudes.