Ju-Hyoung Kima,*, Nahyun Kima, Hanbi Moona, Sukyeon Leea, So Young Jeongb, Guillermo Diaz-Pulidob, Matthew S. Edwardsc, Ju-Hyun Kanga,d, Eun Ju Kange, Hyun-Ju Ohf, Jae-Dong Hwangf, Il-Nam Kime,*
aFaculty of Marine Applied Biosciences, Kunsan National University, Gunsan 54150, South Korea
bSchool of Environment and Science and Australian Rivers Institute-Coast & Estuaries, Nathan Campus, Griffith University, 170 Kessels Road, Nathan, QLD 4111, Australia
cDepartment of Biology, San Diego State University, 5500 Campanile Drive, Physical Sciences 145, San Diego, CA 92182, USA
dKorea Ocean & Fisheries Institute, Tongyeong 53005, South Korea
eDepartment of Marine Science, Incheon National University, Incheon 22012, South Korea
fOceanic Climate and Ecology Research Division, National Institute of Fisheries Science, Busan 46083, South Korea
Dramatic increases in the release of anthropogenic CO2 and global temperatures have resulted in alterations to seawater carbonate chemistry and metabolisms of marine organisms. There has been recent interest in the effects of these stressors on crustose coralline algae (CCA) because photosynthesis and calcification are influenced by all components of carbonate chemistry. To examine this, a mesocosm experiment was conducted to evaluate photosynthesis, calcification and growth in the temperate CCA Chamberlainium sp. under acidification (doubled CO2), warming (+5 °C), and greenhouse (doubled CO2 and +5 °C) conditions compared to present-day conditions. After 47 days of acclimation to these conditions, productivity was lowest under acidification, although photochemical properties were improved, while respiration was highest under warming. Likewise, growth was lowest under acidification, but this negative response was offset by elevated temperature under greenhouse. Together, these results suggest that warming offsets the negative effects of acidification by creating more suitable conditions for photosynthesis and growth.