Primary production in the upper sea ice

Abstract

Observations and expenments were conducted on fast ice in McMurdo Sound, Antarctica, to investigate seasonal changes in primary production in the upper sea ice intenor. In November and early December 1995, a dense phytoflagellate assemblage developed in the brine channels and pockets at a snow-free site. Primary production was calculated from I4C measurements of primary productivity in brine samples combined with estimates of the proportion of the ice volume occupied by brine.On 4 December 1995, when the dinoflagellate PolareUa glacialis dominated, eshmated daily production peaked at 12.4 mg C m-' in the upper 50 cm of ice. On this date, brine temperature was --3°C and brine salinity was -60. By mid-December, daily production d e c h e d by 77 %, but chlorophyll-specific rates of photosynthesis remained high. The decline in production coincided with encystment of P. glacialis and nutnent deplehon, the former triggered by the latter. Pnmary production continued to decrease during December and January. On 9 January 1996, when ice temperatures were --1°C and brine salinlty was -20, there was a brief bloom of small pennate diatoms in the upper ice interior, but chlorophyll-specific rates of photosynthesis were low and estimated daily production was < l mg C m-' Based on I4C uptake and brine volume, algal production in the upper 50 cm of sea ice was 181 mg C m-* for the season (mid-November through mid-January). Increases in phytoflagellate biomass in the upper 90 cm of ice for this same period indicated that produchon was 2 5 6 mg C m-'. Bnef early season blooms of cryo-and halo-tolerant phytoflagellates accounted for most of the primary production in the upper sea ice interior.

Southern Ocean phytoplankton physiology in a changing climate

“…2). During the winter, the sea ice hosts a diverse and metabolically active algal population dominated by psychrophilic diatoms (Stoecker et al, 2000;Kattner et al, 2004;Meiners et al, 2009;Petrou et al, 2010Petrou et al, , 2011c. Satellite derived data, long-term databases and annual research cruises show that the retreat of sea ice initiates a bloom of diatoms in highly stratified waters and shelf areas (Garibotti et al, 2003a, Seasonal changes in open water area, phytoplankton primary productivity and nutrient concentration in the SSIZ from October to March, where the retreat of the sea ice and rapid nutrient drawdown drive the observed succession of Antarctic phytoplankton communities.…”

Seasonal changes in microbial biomass in the first-year ice of the Terre Adélie area (Antarctica)

“…The upper ice is usually a colder, higher irradiated environment than the base of the ice (Stoecker et al 2000). However, sea ice microbes successfully inhabit the surface, interior and bottom of the ice (Horner 1985, Archer et al 1996.…”

Microalgal community structure and primary production in Arctic and Antarctic sea ice: A synthesis

“…Melt-pond communities appear well adapted to high light. Production, however, may be inhibited by depletion of nitrate and phosphate (Stoecker et al, 2000). An increase in nutrient limitation can be reflected in a seasonal decline in P max and α (Stoecker et al, 2000;Fernandez-Mendez et al, 2014).…”

“…Production, however, may be inhibited by depletion of nitrate and phosphate (Stoecker et al, 2000). An increase in nutrient limitation can be reflected in a seasonal decline in P max and α (Stoecker et al, 2000;Fernandez-Mendez et al, 2014). Later in the season, when melt ponds can become connected to the ice interior and even to underlying seawater, a fresh supply of nutrients may be provided (e.g., Mundy et al, 2011).…”