Photokinetic adaptation of sea-ice algae

Metadata record for data from ASAC Project 2702 See the link below for public details on this project. Sea-ice algae are the basis of the Antarctic food web and are essential for healthy functioning of the Antarctic ecosystem. These algae exploit a unique niche within this extreme environment. Using advanced photosynthetic analysis we will examine the mechanisms which influence the productivity of sea-ice algae. The objective of this project is to understand the processes of light acclimation and photo-protection employed by sea-ice algae under extremely low temperature conditions. Several new hypotheses have been proposed in a recent review of low temperature acclimation of higher plants (Oquist and Huner, 2003). To further understand the remarkable tolerance of sea-ice algae to photoinhibition, we propose to test several of these hypotheses. Sea-ice algae fix inorganic carbon that forms the basis of the Southern Ocean food web. Sea ice covers up to 20 million km2 of the Southern Ocean each year. Global climate change will decrease the sea-ice thickness and distribution (IPCC, 2001); however subtle changes in temperature and light penetration will also have profound negative impacts on the photosynthetic efficiency of the sea-ice microalgae before any macroscale changes take place. Sea-ice algae are essentially the only food source for invertebrates and fish for up to nine months of the year. During winter and spring, krill (Euphausia sp.) have been observed feeding directly on sea-ice algae. Further, changes in sea-ice productivity will have a cascade effect further up the food web. Therefore, understanding how physical driving forces (temperature and light) affect sea-ice algae productivity will be critical to our ability to predict the effects of climate change and sustainably manage this unique and vulnerable ecosystem. Our primary objective is: To understand the processes of light acclimation and photo-protection employed by sea-ice algae under extremely low temperature conditions, with an aim to better understanding the potential implications of global climate change on the Antarctic sea-ice ecosystem.