Abstract
We conducted an integrated study of phytoplankton taxonomic composition, biomass and physicochemical properties of the water in Admiralty Bay, South Shetlands. The aim of the study was to provide detailed information on phytoplankton composition and diversity related to relevant environmental conditions. High-performance liquid chromatography pigment analysis and microscopy were performed in the summers of 2007 and 2009–2010. Results for 2007 showed a typical high-nutrient, low-chlorophyll system. Total carbon biomass and cell numbers were dominated by nanoflagellates, while diatoms made up 1.2–4.5 % of the total algal numbers and contributed a maximum of 23.4 % to the total cell carbon. A small algal bloom occurred in the center of the bay, with chlorophyll a values of ~1.0 µg l−1. The prevalent pigment was 19′-hexanoyloxyfucoxanthin, characteristic of the Prymnesiophyceae. In January 2010, the values of chlorophyll a (8–24 µg l−1) and cell carbon (150 µg l−1) were the highest ever recorded for Admiralty Bay. In general the algal populations were dominated numerically by nanoflagellates, but a bloom of diatoms (maximum 30 % of total cells and 50 % of total cell carbon) was observed. Diatoms were dominated by those of micro-size: Thalassiosira ritscheri and T. antarctica. The dominant pigment was fucoxanthin, mainly found in diatoms. The diatom bloom could be related to the southeast wind direction, stable water column conditions and an inflow of diatom-rich waters from the Bransfield Strait, while the input of high-turbidity, low-salinity water from melting glaciers and strong katabatic northwest winds could favor nanoflagellates.
Highlights
We conducted an integrated study of phytoplankton taxonomic composition, biomass and physicochemical properties of the water in Admiralty Bay, South Shetlands
Total carbon biomass and cell numbers were dominated by nanoflagellates, while diatoms made up 1.2–4.5 % of the total algal numbers and contributed a maximum of 23.4 % to the total cell carbon
The pigments were identified by comparing their retention times and absorption spectra with standards (DHI Lab Products) and with data in the literature (Jeffrey et al In 2007, the average water column salinities varied from 33.8 ± 0.3 practical salinity units (PSU) at a cove in the vicinity of melting glaciers to 34.1 ± 0.09 PSU in Ezcurra Inlet
Summary
We conducted an integrated study of phytoplankton taxonomic composition, biomass and physicochemical properties of the water in Admiralty Bay, South Shetlands. In January 2010, the values of chlorophyll a (8–24 lg l-1) and cell carbon (150 lg l-1) were the highest ever recorded for Admiralty Bay. In general the algal populations were dominated numerically by nanoflagellates, but a bloom of diatoms (maximum 30 % of total cells and 50 % of total cell carbon) was observed. Previous investigations of phytoplankton community structure and composition in Admiralty Bay, carried out in various seasons and summarized by Kopczynska (2008), have revealed year-round dominance (in number and biomass) of nano-size cells, mainly nanoflagellates, over micro-size cells such as diatoms. The contribution of diatoms to the total cell numbers has been declining, from approximately 44 % in 1996–1998 to 5 % in 2003–2005 This finding was based on water samples from both the central bay and shore assemblages, the latter in the vicinity of the Henryk Arctowski Polish Antarctic Station. The total annual productivity in surface waters in the center of the bay was estimated at 6.6 g C m-3 year-1; in summer 1988, the mean primary productivity was only 10 mg C m-3 year-1 (Domanov and Lipski 1990)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
