Tidal action and macroalgal photosynthetic activity prevent coastal acidification in an eutrophic system within a semi-desert region

BECHERUCCI, MARIA EUGENIA; PEREYRA, PATRICIO; NARVARTE, MAITE; FANJUL, EUGENIA; IRIBARNE, OSCAR; MARTINETTO, PAULINA

ESTUARINE COASTAL AND SHELF SCIENCE

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2021

0272-7714

Temporal and spatial coastal seawater pH variability can be driven by macroalgae photosynthetic activity. We tested this hypothesis with field sampling and experiments in a semi-desert macrotidal coastal system with contrasting eutrophic conditions and Ulva lactuca blooms in northern Patagonia, Argentina. Our results indicate that daily pH variability during low tide is controlled by the photosynthetic activity of Ulva lactuca under eutrophic conditions. At seasonal scale, the pH variations were related to environmental features, particularly seawater temperature. Both environmental (i.e. high solar radiations, the negligible freshwater inputs, and the large tidal water exchange) and anthropogenic (i.e. nutrient inputs) features of the studied area promote the Ulva lactuca blooms, which in turn increases the surrounding pH in well oxygenated seawaters through the intense photosynthetic activity. Thus, this study is an example in which eutrophication, under the above mentioned conditions, instead of being a driver of coastal acidification it rather contributes to its prevention.