Biosynthesis of macromolecular and lipid classes by phytoplankton in the Northeast Water Polynya

Abstract

The patterns and environmental correlates of macromolecular synthesis were investigated during 1993 in the Northeast Water Polynya, a region of variable ice cover and hydrodynamic regime on the continental shelf of northeast Greenland (77" to 81' N). Allocation of photosynthate to major macromolecular classes (protein, lipid, and polysaccharides), like phytoplankton biomass and primary production, showed strong spatio-temporal variability. Time series observations in the central part of the polynya and correlational analysis over all stations provided physiological evidence of nutrient deficiency in surface populations as nitrate and silicate were depleted. Lipid, rather than polysaccharide, synthes~s was favoured as nutrient concentrations decreased, and C/N assimilation ratios inferred from protein labelling reached very high values ( > l 5 by weight). C/N composition ratios increased in parallel but remained lower (<10) than the assimilation ratios. Lipid synthesis shifted towards neutral lipids and glycolipids, and away from phospholipids, as nutrient concentrations declined to their observed minimum. At stations with a dominance of large (mainly diatom) phytoplankton more of the lipid synthesis was directed to glycolipids and less to phospholipids and neutral lipids than at those dominated by small (mainly flagellate) phytoplankton, but relative allocation to total lipids and other macromolecular classes was not significantly different between the 2 types of stations. Although both nitrate and silicate became depleted, changes in silicate were most closely related to the physiological changes observed, consistent with a predominance of diatoms at the more productive stations.

Short-term changes in particulate fluxes measured by drifting sediment traps during end summer oligotrophic regime in the NW Mediterranean Sea

“…With the decline in chlorophyll concentration as the season advanced towards autumn, phospholipids, triacylglycerols and wax esters dominated the lipid material in the traps. Change in POM and DOM lipid composition from a glycolipidsdominated lipid pool, to a neutral (wax esters, triacylglycerols) and phospholipids-dominated lipid pool, has already been observed in ecosystems changing from micro-and or pico-phytoplankton to heterotrophs-dominated regimes (Smith et al, 1997;Goutx et al, 2000;Ghiglione et al, 2007;Bourguet et al, 2008). During DYNAPROC 2, a similar shift occurred in the suspended particles and dissolved matter .…”

Factors influencing particulate lipid production in the East Atlantic Ocean

“…The low amounts of WE in our study indicated only a minor contribution of larger zooplankton known to synthesize WE in contrast to the small subtropical and tropical species which do not store lipids (Kattner and Hagen, 2009). In addition to the influence of nutrient availability on the phytoplankton composition, nutrient depletion is also favorable to enhancing lipid synthesis (Shifrin and Chishilm, 1981;Smith et al, 1997;Frka et al, 2011). The higher ratios of lipids to Chl a (Fig.…”

LINKING TIME‐DEPENDENT CARBON‐FIXATION EFFICIENCIES IN DUNALIELLA TERTIOLECTA (CHLOROPHYCEAE) TO UNDERLYING METABOLIC PATHWAYS1

“…1992). Changes in the fraction of labeled lipids have been associated with nutrient availability and species succession (Sukenik and Livne 1991, Smith et al. 1997).…”

“…Nutrient limitation is known to influence this oxidation:reduction index (Smith and Geider 1985, Hama et al. 1988, Smith et al. 1997, Jakob et al.…”