Tools
Tools
Mock, Thomas 
ORCID: https://orcid.org/0000-0001-9604-0362 and Gradinger, Rolf
(2000)
Changes in photosynthetic carbon allocation in algal assemblages of Arctic sea ice with decreasing nutrient concentrations and irradiance.
Marine Ecology Progress Series, 202.
pp. 1-11.
ISSN 0171-8630
Abstract
Photosynthetic carbon assimilation into protein, low-molecular-weight metabolites (LMWM), polysaccharides, total lipids and into 3 lipid classes (neutral lipids, glycolipids and phospholipids) was determined in batch-culture experiments with natural assemblages of Arctic-ice algae under simulated in situ irradiance. Photosynthate allocation in 3 parallel batch incubations revealed a high contribution of lipid assimilation to total particulate carbon production (54.6 ± 0.4%) followed by LMWM (35.0 ± 1.0%), carbohydrates (7.3 ± 0.1%) and proteins (3.0 ± 0.8%). Total lipids were mainly composed of glycolipids (67.4 ± 3.5%) with a relatively lower allocation into phospholipids (28.1 ± 6.7%) and neutral lipids (4.5 ± 3.2%). Nutrient addition (final concentrations: Si(OH)4 = 65.5 ± 0.4 µmol l-1, NO3 = 42.9 ± 0.6 µmol l-1, PO4 = 2.6 ± 0.0 µmol l-1) caused algal community growth of 0.22 ± 0.0 d-1 until nutrients became limiting 10 d later. Si(OH)4:NO3 ratios and NO3:PO4 ratios in the cultures decreased from initially 1.5 ± 0.0 to 0.2 ± 0.1 and 16.8 ± 0.2 to 1.2 ± 0.5, respectively. During the first few days of incubation, relative proportions of carbon production for proteins increased 3-fold (max. 11.1 ± 1.0%), those for LMWM 1.5-fold (max. 45.7 ± 6.4%), whereas lipids decreased (min. 32.0 ± 0.4%). Increasing relative proportions of carbon production for carbohydrates were only observed at the end of exponential growth (max. 12.9 ± 1.3%). A dramatic increase of lipids was measured under nutrient depletion (max. 70.9 ± 3.6%) after Day 10, which was the result of glycolipid production, while protein and carbohydrate production decreased to values below 5% of total particulate carbon production. LMWM also attained lower incorporation rates under nutrient depletion (min. 23.5 ± 1.1%). Production of glycolipids during exponential algal growth is attributed to an acclimation to decreasing irradiance as a consequence of an increase in algal biomass. Decreasing particulate carbon:chlorophyll a ratios during the experiment indicate a physiological response to a reduction in irradiance with simultanous glycolipid production. Glycolipids are the main lipid class in chloroplasts, and especially in thylakoidmembranes, which are strongly developed during low-light acclimation. Excess light energy during stationary algal growth after Day 10 is dissipated in the form of glycolipids and/or neutral lipids. But the latter are probably more significant under high-light conditions.
| Item Type: | Article |
|---|---|
| Faculty \ School: | Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA |
| UEA Research Groups: | Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation Faculty of Science > Research Groups > Environmental Biology Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences |
| Depositing User: | Rosie Cullington |
| Date Deposited: | 01 Jul 2011 08:57 |
| Last Modified: | 13 Apr 2023 13:41 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/33146 |
| DOI: | 10.3354/meps202001 |
Actions (login required)
 |
View Item |