Planktonic ciliates in different water masses in open waters near Prydz Bay (East Antarctica) during austral summer, with an emphasis on tintinnid assemblages

Chen Liang,Zhencheng Tao,Haibo Li,Wuchang Zhang,Gerald Gregori,Yi Dong,Yuan Zhao,Chaolun Li

doi:10.1007/s00300-018-2375-5

Abstract

Planktonic ciliates are important microzooplankton in pelagic ecosystems. Previous studies in Antarctic waters have only investigated ciliate assemblages in different habitats without considering water masses. In this article, we report the characteristics of ciliate assemblages in different water masses in open waters near Prydz Bay (East Antarctica) during austral summer. Three water masses were identified according to temperature and salinity: Summer Surface Water (SSW), Winter Water (WW), and Circumpolar Deep Water (CDW). SSW was further divided into SSWChl a 3 mg m−3) and SSWChl a WW > CDW. SSWChl a > 3 had a higher proportion (38.2%) of tintinnids to the total ciliate abundance and larger aloricate ciliates (ciliates in the 10–20 µm size class were 30%) of Southern Ocean endemic tintinnid species in total tintinnid abundance than in other water masses. Each water mass had the following indigenous tintinnid species: SSW, Salpingella sp., Codonellopsis gaussi; WW, Salpingella costata, S. faurei, Cymatocylis affinis/convallaria forma drygalskii, and C. vanhoeffeni. Laackmanniella naviculaefera and C. affinis/convallaria forma cristallina were present at high abundance in both WW and SSWChl a > 3. Upwelling caused discontinuity of the ciliate distribution. Our results will help predict the spatial and temporal variations of ciliate assemblages and other plankton according to the dynamics of water masses in Antarctic waters.

Highlights

Marine planktonic ciliates constitute a major, ubiquitous, and diverse group of protozoa
Water masses are well defined in the Southern Ocean (Tomczak and Godfrey 1994), no studies have investigated the relationship between ciliates and different water masses in this ocean to date
According to the spatial distribution of the concentration of Chlorophyll a (Chl a), Summer Surface Water (SSW) was divided into an area with Chl a concentration > 3 mg m−3 near the shelf and another area with concentration < 3 mg m−3 in the north

Summary

Introduction

Marine planktonic ciliates constitute a major, ubiquitous, and diverse group of protozoa. Planktonic ciliates feed on nanoplankton (Heinbokel and Beers 1979; Capriulo 1983; Verity 1987) and picoplankton (Bernard and Rassoulzadegan 1993), while they are preyed upon by mesoplankton and fish larvae (Azam et al 1983; Lavalpeuto et al 1986; Pierce and Turner 1992, 1994). In Antarctic waters, ciliate abundance was observed in different habitats (oceanic areas, transitional areas, polynyas, edges of glaciers, and edges of sea ice) in the Amundsen Sea (e.g., Jiang et al 2014, 2015, 2016) and the Weddell Sea (e.g., Heinbokel and Coats 1986; Garrison and Buck 1989; Garrison et al 1991; Gowing and Garrison 1992) These investigations generally evaluated ciliate assemblages at a horizontal level while providing very little vertical distribution information. Water masses are well defined in the Southern Ocean (Tomczak and Godfrey 1994), no studies have investigated the relationship between ciliates and different water masses in this ocean to date

Methods

Results

Conclusion