Biosynthesis and photosynthate allocation patterns of arctic ice algae

• Main Authors: Ralph E. H. Smith, Pierre Clgment, Erica Head
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1989
• Subjects: Arctic; Sullivan; ice algae; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.539.2047; http://www.aslo.org/lo/toc/vol_34/issue_3/0591.pdf

Biochemical composition of the sea ice microbial community was measured in populations of different light histories in the Canadian Arctic (Resolute, N.W.T.). The average composition of the particulate organic matter [soluble and insoluble polysaccharide, particulate protein, intracel-lular free amino acids (IFAA), lipid, and chlorophyll a] was within the published range for mi-croalgae, but lipid was a relatively large (3 l-59%) and protein a small (20-24%) part of the total. Protein and IFAA pools apparently comprised about 50 % of the particulate organic nitrogen, of which 6-10 % was in the IFAA pool. Over the cntirc spring growth season, the net synthesis of protein, IFAA, and Chl a (relative to total cell carbon) decreased with increasing light while relative synthesis of lipid and soluble polysaccharide increased, consistent with patterns of short-term photosynthate allocation. In the early growth season patterns of synthesis were relatively insensitive to light, and rates of lipid synthesis were large for all light histories. Photosynthate allocation in 24-h incubations greatly underestimated actual rates of net lipid synthesis and probably overes-timated protein synthesis. Microalgae of cold, low-light environments can display rates of lipid synthesis much larger than rates normally encountered in microalgae without displaying a corre-sponding pattern of shorter term photosynthate allocation. Sea ice algae have attracted attention for their potential importance as contributors to primary production in polar regions (Horner and Schrader 1982; Palmisano and Sullivan 1983) and for the chance they af-ford to study the adaptation of microauto-trophs to prolonged conditions of low light and temperature (McConville 198 5). Arctic ice algae experience a low photon flux den-sity (PFD) determined largely by the depth of ice and snow overlying them (Maykut 1985; Gosselin et al. 1985) and by their own self-shading (Palmisano and Sullivan 1983).