Impacts of Seagrass on Benthic Microalgae and Phytoplankton Communities in an Experimentally Warmed Coral Reef Mesocosm

• Published in: Frontiers in Marine Science Vol. 8
• Main Authors: Tew, Kwee Siong, Kuo, Jimmy, Cheng, Jing-O, Ko, Fung-Chi, Meng, Pei-Jie, Mayfield, Anderson B., Liu, Pi-Jen
• Format: Journal Article
• Language: English
• Published: Lausanne Frontiers Research Foundation 10.06.2021; Frontiers Media S.A
• Subjects: Acidification; Algae; Ammonium; Ammonium compounds; Aquatic microorganisms; Benthos; Carbon dioxide; Chlorophyll; Chlorophyll a; Cladocopium; climate change; Coral reefs; Dinoflagellata; Dinoflagellates; Experiments; High temperature; Mesocosms; Microalgae; nutrients; Ocean acidification; Phytoplankton; Primary production; Salinity; Sea grasses; seagrass; Seawater; sedimentation; Symbionts; Water quality; United States > US; Taiwan
• ISSN: 2296-7745; 2296-7745
• DOI: 10.3389/fmars.2021.679683

The effects of seagrass on microalgal assemblages under experimentally elevated temperatures (28°C) and CO 2 partial pressures (pCO 2 ; 800 μatm) were examined using coral reef mesocosms. Concentrations of nitrate, ammonium, and benthic microalgal chlorophyll a (chl-a) were significantly higher in seagrass mesocosms, whereas phytoplankton chl-a concentrations were similar between seagrass and seagrass-free control mesocosms. In the seagrass group, fewer parasitic dinoflagellate OTUs (e.g., Syndiniales) were found in the benthic microalgal community though more symbiotic dinoflagellates (e.g., Cladocopium spp.) were quantified in the phytoplankton community. Our results suggest that, under ocean acidification conditions, the presence of seagrass nearby coral reefs may (1) enhance benthic primary productivity, (2) decrease parasitic dinoflagellate abundance, and (3) possibly increase the presence of symbiotic dinoflagellates.