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Harmful algal blooms: mechanisms, monitoring, and prevention in a rapidly changing world
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Ocean acidification and nutrient limitation synergistically reduce growth and photosynthetic performances of a green tide alga Ulva linza Wednesday 9th @ 1410-1430, Multifunction Hall Guang Gao* , State Key Laboratory of Marine Environmental Science, Xiamen University John Beardall, School of Biological Sciences, Monash University Menglin Bao, Jiangsu Key Laboratory for Coastal Resources and Eco-environment, Huaihai Institute of Technology Can Wang, Jiangsu Key Laboratory for Coastal Resources and Eco-environment, Huaihai Institute of Technology Wangwang Ren, Jiangsu Key Laboratory for Coastal Resources and Eco-environment, Huaihai Institute of Technology Juntian Xu, Jiangsu Key Laboratory for Coastal Resources and Eco-environment, Huaihai Institute of Technology Presenter Email: biogaoguang@126.com |
Large-scale green tides have been invading the coastal zones of the western Yellow Sea annually since 2008. Eutrophication is deemed to be the first cause that drives green tides. Meanwhile, oceans are becoming more acidic due to continuous absorption of anthropogenic carbon dioxide, However, little is known about the combined effects of nutrient and ocean acidification on the eco-physiology of green tide algae. We cultured Ulva linza for 9-16 days under two levels of pCO2 (400 and 1000 ¦Ìatm) and four treatments of nutrients (nutrient repletion, N limitation, P limitation, and N-P limitation) to investigate the physiological responses of this green tide alga to the combination of ocean acidification and nutrient limitation. For both sporelings and adult plants, elevated pCO2 did not affect the growth rate when cultured under nutrient-replete conditions but reduced it under P limitation; N or P limitations by themselves reduced growth rate. P limitation resulted in a larger inhibition in growth for sporelings compared to adult plants. Sporelings under P limitation did not reach the mature stage after 16 days of culture while those under P repletion became mature by day 11. Elevated pCO2 reduced net photosynthetic rate for all nutrient treatments but increased nitrate reductase activity and soluble protein content under P-replete conditions. N or P limitation reduced nitrate reductase activity and soluble protein content. These findings indicate that ocean acidification and nutrient limitation would synergistically reduce the growth of Ulva species and may thus hinder the occurrence of green tides in a future ocean environment. |
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