Effects of acidification on the biogeochemistry of unvegetated and seagrass marine sediments

Published 14 February 2024 Science Leave a Comment
Tags: chemistry, field, Mediterranean, sediment

Highlights

• A −0.3 pH units difference causes minor effects on unvegetated sediments organic matter
• Acidification slows down organic C degradation in unvegetated sediments
• Acidification stimulates organic C in seagrass sediments
• Acidification will affect benthic trophic webs under worsening ocean scenarios

Abstract

Many studies addressed ocean acidification (OA) effects on marine life, whereas its effects on sedimentary organic matter (OM) have received less attention. We investigated differences in OM features in sediments from unvegetated and seagrass (Posidonia oceanica) beds in a shallow hydrothermal area (Aeolian Archipelago, Mediterranean Sea), under natural (8.1–8.0) and acidified (7.8–7.9) conditions. We show that a pH difference of −0.3 units have minor effects on OM features in unvegetated sediments, but relevant consequences within acidified seagrass meadows, where OM quantity and nutritional quality are lower than those under natural pH conditions. Effects of acidified conditions on OM biogeochemistry vary between unvegetated and seagrass sediments, with lower C degradation rates and longer C turnover time in the former than in the latter. We conclude that OA, although with effects not consistent between unvegetated and vegetated sediments, can affect OM quantity, composition, and degradation, thus having possible far-reaching consequences for benthic trophic webs.

Soru S., Berlino M., Sarà G., Mangano M. C., De Vittor C. & Pusceddu A., 2024. Effects of acidification on the biogeochemistry of unvegetated and seagrass marine sediments. Marine Pollution Bulletin 199: 115983. doi: 10.1016/j.marpolbul.2023.115983. Article (subscription required).

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