Spring sea ice photosynthesis, primary productivity and biomass distribution in eastern Antarctica, 2002–2004

Abstract

While it is known that Antarctic sea ice biomass and productivity are highly variable over small spatial and temporal scales, there have been very few measurements from eastern Antarctic. Here we attempt to quantify the biomass and productivity and relate patterns of variability to sea ice latitude ice thickness and vertical distribution. Sea ice algal biomass in spring in 2002, 2003 and 2004 was low, in the range 0.01-8.41 mg Chl a m -2 , with a mean and standard deviation of 2.08 ± 1.74 mg Chl a m -2 (n = 199). An increased concentration of algae at the bottom of the ice was most pronounced in thicker ice. There was little evidence to suggest that there was a gradient of biomass distribution with latitude. Maximum in situ production in 2002 was approximately 2.6 mg C m -2 h -1 with assimilation numbers of 0.73 mg C (mg Chl a) -1 h -1 . Assimilation numbers determined by the 14 C incubations in 2002 varied between 0.031 and 0.457 mg C (mg Chl a) -1 h -1 . Maximum fluorescence quantum yields of the incubated ice samples in 2002 were 0.470 ± 0.041 with E k indices between 19 and 44 lmol photons m -2 s -1 . These findings are consistent with the shade-adapted character of ice algal communities. In 2004 maximum in situ production was 5.9 mg C m -2 h -1 with an assimilation number of 5.4 mg C (mg Chl a) -1 h -1 . Sea ice biomass increased with ice thickness but showed no correlation with latitude or the time the ice was collected. Forty-four percent of the biomass was located in bottom communities and these were more commonly found in thicker ice. Surface communities were uncommon.

Southern Ocean Phytoplankton in a Changing Climate

“…Primary production by sea ice algae contributes between 24-70 Tg C yr −1 (Legendre et al, 1992;Arrigo et al, 1997;Saenz and Arrigo, 2014) and phytoplankton biomass averages between 1 and 100 mg Chl a m −2 , although it can exceed 1000 mg Chl a m −2 in some regions (Lizotte, 2001;Arrigo et al, 2010). Ice algal biomass and productivity varies greatly at small spatial and temporal scales, primarily due to changes in snow cover, ice thickness, surface flooding, and ice rafting (McMinn et al, 2007;Meiners et al, 2012;Arrigo, 2014 and references within). Thus, ice algae are able to thrive in this harsh physical environment.…”

“…The majority of the sea ice in the SSIZ is first-year ice, with ice thickness seldom exceeding 2 m (Worby et al, 2008;Meiners et al, 2012). Ice algal biomass is often concentrated in the bottom 20 cm of the ice (Palmisano and Sullivan, 1983;McMinn et al, 2007;Meiners et al, 2012), with thicker ice (>1.0 m) supporting higher algal biomass than thin ice (<0.4 m), due to longer time for colonization and growth of the bottom ice algal community, along with development of internal communities from the rafting of ice floes (McMinn et al, 2007;Meiners et al, 2012). Thus, a decline in sea ice thickness may result in a reduction in bottom community biomass, which is an important food source for zooplankton (Brierley and Thomas, 2002;Jia et al, 2016), thereby causing a shift in the diet of Antarctic birds and mammals toward less efficient pathways (Murphy et al, 2007;Moline et al, 2008;Flores et al, 2012;Ballerini et al, 2014).…”

Oxygen exchange and ice melt measured at the ice-water interface by eddy correlation

“…The conversion of PAM data into carbon (or O 2 ) fluxes further complicates the method as frequent intercalibration to poorly constrained empirical relationships are required. Microsensor profiling using both Clark-type O 2 microsensors and O 2 micro-optodes has also been used to examine icewater O 2 fluxes but can suffer from calibration problems due to temperature and salinity gradients and spatial microvariability in the ice (McMinn and Ashworth, 1998;Glud et al, 2002;Mock et al, 2003;McMinn et al, 2007).…”

Antarctic sympagic meiofauna in winter: Comparing diversity, abundance and biomass between perennially and seasonally ice-covered regions

“…Pigments were extracted in 90% acetone for 6-12 h at À25 1C (Gradinger, 1999b) after ultrasonic cell disruption during ANT-XXIII/7 or in 100% methanol for 24 h at 0 1C (McMinn et al, 2007) without cell disruption during SIPEX. Pigment concentrations were determined by fluorometric measurements (Turner 10-AU fluorometer, detection limit 0:1 mg L À1 ) before and after acidification with 0.1 N HCl.…”