College of Ocean and Earth Sciences, Xiamen University
Mesocosm facility for ocean acidification impact study
2016/9/1 158

The pH of the world’s surface oceans is falling as a result of anthropogenic CO2 penetration into the ocean. Such an ocean acidification phenomenon is progressing at an unprecedented rate in Earth’s history. The rate of change has been estimated to be faster than at any time in the last 300 million years. The acidity of surface oceans is predicted to increase by 150% by the end of this century. The far-reaching effects of ocean acidification on food webs, biodiversity, fisheries and aquaculture, and societies are of concern to scientific communities and the public at large. Predicting how organisms and ecosystems will change in respond to ocean acidification remains challenging.

To explore the mechanistic influences of ocean acidification, the Mesocosm Facility for Ocean Acidification Impact Study of MEL (FOANIC-XMU) has been successfully set up in Wuyuan Bay (24°31′48″N, 118°10′47″E). The 35m×7m floating platform, has three separate rooms (9m2 each) and nine 4m3 mesocosms and is fully solar-powered for all instruments on board. Activities on the platform are monitored and recorded continuously. Different levels of CO2 in the mesocosms can be achieved by a commercially available CO2-enriching device (CO2 enricher, Ruihua, Wuhan, China). Ocean acidification (OA) conditions can be induced gradually with aeration from the CO2 enrichers. Effects of OA on phytoplankton species competition, primary productivity, food chain effect and microbial processes will be examined by the MEL group and their collaborating scientists to look into the OA impacts on species, community, and ecosystem levels.

The first experiment has been carried out during May to July, 2013 to understand the competition of different phytoplankton groups, mainly diatoms and coccolithorphores, under ambient and elevated CO2 concentrations, which are achieved with a CO2-enriching device. Another mesocosm experiment is carried out in March, 2014 to investigate the effects of OA on shellfish development and shellfish farming ecosystem processes.

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