Studies on ocean acidification have mostly been based on short-term experiments of low latitude with few investigating the long-term influence on sea-ice communities. Here, the combined effects of ocean acidification and photoperiod on the physiological response of an Antarctic sea ice microalgae Chlamydomonas sp. ICE-L were examined. There was a general increase in growth, PSII photosynthetic parameters, N and P uptake in continuous light, compared to those exposed to regular dark and light cycle. Elevated pCO2 showed no consistent effect on growth rate (p=0.8) and N uptake (p=0.38) during exponential phrase, depending on the photoperiod. But it had a positive effect on PSII photosynthetic capacity and P uptake. Continuous dark reduced growth, photosynthesis, and nutrient uptake. Moreover, intracellular lipid, mainly in the form of PUFA, was consumed by 80% and 63% in low and high pCO2 in darkness. However, long-term culture under high pCO2 gave a more significant inhibition of growth and Fv/Fm to high light stress. In summary, ocean acidification may have significant effects on Chlamydomonas sp. ICE-L survival in polar winter. The current study contributes to an understanding of how a sea ice algae-based community may response to global climate change at high latitudes.
Xu D., Wang Y., Fan X., Wang D., Ye N. , Zhang X., Mou S., Guan Z. & Zhuang Z., in press. Long-term experiment on physiological responses to synergetic effects of ocean acidification and photoperiod in Antarctic sea ice algae Chlamydomonas sp. ICE-L. Environmental Science & Technology. Article (subscription required).
