Diversity and distribution of tintinnid ciliates along salinity gradient in the Pearl River Estuary in southern China

Haibo Li (1, 2) , Chaofeng Wang (1, 2, 3) , Chen Liang (1, 2, 3) , Yuan Zhao (1) , Wuchang Zhang (1, 2) , Gérald Grégori (4) , Tian Xiao (1, 2)

1 Qingdao National Laboratory for Marine Science and Technology
2 Center for Ocean Mega-Science [Qingdao]
3 UCAS - University of Chinese Academy of Sciences [Beijing]
4 MIO - Institut méditerranéen d'océanologie

Tintinnid community structure in the Pearl River Estuary were investigated 6 times (10, 29 October 2014; 11, 30 June 2015 and 15 March, 1 April 2017) from upstream freshwaters to polyhaline waters. A total of 43 tintinnid species in 15 genera were identified. Freshwater, brackish and marine species occurred in sequence along salinity gradient. Tintinnopsis mayeri, T. tubulosa and Tintinnidium fluviatile were freshwater species. Fourteen and 15 tintinnid species were considered as brackish and marine species, respectively. The preferred salinity of freshwater species was <3, and the abundance of freshwater species decreased along salinity gradient. Preferred salinity of brackish species ranged in 3–23. High abundance of brackish species occurred at mesohaline regions and decreased towards both oligohaline and polyhaline regions. Marine species abundance dropped sharply with the decrease of salinity, and seldom appeared when salinity was <15. Tintinnid species richness was low at low salinity areas. With the increase of salinity, tintinnid species richness showed different variation patterns in different seasons. Tintinnid abundance showed bimodal-peak along salinity gradient. The first abundance peak was mainly contributed by brackish species and occurred where salinity was < 15. While the second abundance peak appeared where salinity was around 25 or > 30, which was mainly contributed by marine species. Low salinity, brackish and coastal tintinnid communities were divided based on the abundance percentage variations of different tintinnid types. Complexities of those communities increased along salinity gradient.

Mots clés: Pearl river estuary; Species richness; Abundance; Salinity gradient; Tintinnid ciliates

Domaines: Océan, Atmosphère

Haibo Li, Chaofeng Wang, Chen Liang, Yuan Zhao, Wuchang Zhang, et al.. Diversity and distribution of tintinnid ciliates along salinity gradient in the Pearl River Estuary in southern China. Estuarine, Coastal and Shelf Science, 2019, 226, pp.106268. ⟨10.1016/j.ecss.2019.106268⟩. ⟨hal-02185988⟩