The effects of increasing CO2 concentrations and temperature on microalgal assemblages were examined in Taiwan using mesocosms that simulate coral reef ecosystem. We assessed changes in abundance and diversity of benthic algae grown at 25 °C and 28 °C, under ambient (~ 400 μatm) and at high CO2 conditions (800–1000 μatm). Total alkalinity, pCO2, and the aragonite saturation state, were all significantly different between control and high CO2 treatments in both temperature treatments. Chl a concentration increased significantly in CO2-treated groups at 25 °C, but benthic microalgal abundance was not significantly different. The number of microalgal species and the microalgal community structure did not differ between control and CO2-treated groups at both temperatures. Our results suggest that increasing CO2may boost benthic microalgal primary productivity if sufficient nutrients are available, although site-specific responses are difficult to predict.
Tew K. S., Siao I. J., Liu P. J., Lo W. T. & Meng P. J., in press. Taiwanese marine microbenthic algal communities remain similar yet chlorophyll a concentrations rise in mesocosms with elevated CO2 and temperature. Marine Pollution Bulletin. Article (subscription required).