Survival and recovery of Phaeocystis antarctica (Prymnesiophyceae) from prolonged darkness and freezing

Abstract

The colony-forming haptophyte Phaeocystis antarctica is an important primary producer in the Ross Sea, and must survive long periods of darkness and freezing temperature in this extreme environment. We conducted experiments on the responses of P. antarctica-dominated phytoplankton assemblages to prolonged periods of darkness and freezing. Chlorophyll and photosynthetic capacity of the alga declined nonlinearly and independently of each other in the dark, and darkness alone would potentially reduce photosynthetic capacity by only 60 per cent over 150 days (approximately the length of the Antarctic winter in the southern Ross Sea). The estimated reduction of colonial mucous carbon is higher than that of colonial cell carbon, suggesting metabolism of the colonial matrix in the dark. The alga quickly resumed growth upon return to light. Phaeocystis antarctica also survived freezing, although longer freezing durations lengthened the lag before growth resumption. Particulate dimethylsulfoniopropionate relative to chlorophyll increased upon freezing and decreased upon darkness. Taken together, the abilities of P. antarctica to survive freezing and initiate growth quickly after darkness may provide it with the capability to survive in both the ice and the water column, and help explain its repeated dominance in austral spring blooms in the Ross Sea and elsewhere in the Southern Ocean.

Sea ice algal biomass and physiology in the Amundsen Sea, Antarctica

“…19-Hex is a marker pigment for Phaeocystis antarctica, a colonial prymnesiophyte that forms dense blooms in open waters on Antarctic continental shelves (Arrigo et al, 1999). Although this species has been observed previously in newly formed sea ice (Arrigo et al, 2003), and can tolerate prolonged darkness and freezing (Tang et al, 2009), the results of this study are the first to imply that it was physiologically active in the upper layers of sea ice in late spring/early summer. Its presence in recently flooded sea ice may indicate that it was introduced to the ice relatively recently and was able to grow there because of its ability to withstand high light levels.…”

Long‐term pigment dynamics and diatom survival in dark sediment

“…Murphy and Cowles (1997) investigated the photosynthetic capacity of a pelagic diatom by directly measuring in vivo multi-excitation chlorophyll a fluorescence of a Thalassiosira weissflogii culture during 2 months of darkness and found a strong retention of photosynthetic capacity. Tang et al (2009) investigated the retention of photosynthetic capacity of Phaeocystis antarctica under dark and cold conditions and found a substantial reduction of photosynthetic capacity over several months, and also that recovery of photosynthetic capacity required 20 d upon re-exposure to light. Altogether, results from these studies on pelagic algae confirm the ability of algae to retain their photosynthetic capacity up to several months in darkness.…”

Rapid DMSP production by an Antarctic phytoplankton community exposed to natural surface irradiances in late spring

“…Species/groups as for Table 2 (Expt 1), except auto dino also includes an unidentified 10 µm autotrophic Gymnodinium species. Significant increases (d 0 −d 2 ) are shown in bold except for total bacteria, as significance or otherwise of increases could not be assessed from the flow cytometry counts Marchant 1992 and references therein, Tang et al 2009) increased significantly in all treatments in the first 1−4 d, with by far the most rapid early increase occurring in the UVA treatment (Table 2). It is noteworthy that this early increase of P. antarctica occurred despite Thomson et al (2008) finding significant inhibition in this treatment at the end of the exposure period (d 14 ), which included inhibition of P. antarctica.…”