Turf algal epiphytes metabolically induce local pH increase, with implications for underlying coralline algae under ocean acidification

• Published in: Estuarine, Coastal and Shelf Science
• Main Authors: Short, J.A., Pedersen, Ole, Kendrick, G.A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: Acidification; Calcification; Coralline algae; Diffusive boundary layer; pH; Photosynthesis; Ocean acidification
• Online Access: https://curis.ku.dk/portal/da/publications/turf-algal-epiphytes-metabolically-induce-local-ph-increase-with-implications-for-underlying-coralline-algae-under-ocean-acidification(baf7cd5f-95b2-4405-9871-57ea94eaa091).html; https://doi.org/10.1016/j.ecss.2015.08.006

The presence of epiphytic turf algae may modify the effects of ocean acidification on coralline algal calcification rates by altering seawater chemistry within the diffusive boundary layer (DBL) above coralline algal crusts. We used microelectrodes to measure the effects of turf algal epiphytes on seawater pH and the partial pressure of oxygen (pO 2 ) within the DBL at the surface of Hydrolithoideae coralline algal crusts under ambient (36 Pa) CO 2 and an ocean acidification scenario with elevated CO 2 (200 Pa). Turf algae significantly increased the mean diel amplitude of pH and pO 2 , and this effect was more pronounced under elevated CO 2 . We suggest that increases in seawater CO 2 under ocean acidification conditions may drive an increase in the abundance of epiphytic turf algae, consequently modifying the chemistry within the DBL. Thus, the effect of epiphytic turf algae on microscale pH is striking and will likely affect coralline algal response to ocean acidification, highlighting the importance of understanding the effects of environmental change on species interactions.