Simulated leakage of high pCO2 water negatively impacts bivalve dominated infaunal communities from the Western Baltic Sea.

Hanna Schade,Frank Melzner,Katja Guilini,Stefanie Meyer,Stanislav N Gorb,Doris Abele,Ann Vanreusel,Lisa Mevenkamp

doi:10.1038/srep31447

Abstract

Carbon capture and storage is promoted as a mitigation method counteracting the increase of atmospheric CO2 levels. However, at this stage, environmental consequences of potential CO2 leakage from sub-seabed storage sites are still largely unknown. In a 3-month-long mesocosm experiment, this study assessed the impact of elevated pCO2 levels (1,500 to 24,400 μatm) on Cerastoderma edule dominated benthic communities from the Baltic Sea. Mortality of C. edule was significantly increased in the highest treatment (24,400 μatm) and exceeded 50%. Furthermore, mortality of small size classes (0–1 cm) was significantly increased in treatment levels ≥6,600 μatm. First signs of external shell dissolution became visible at ≥1,500 μatm, holes were observed at >6,600 μatm. C. edule body condition decreased significantly at all treatment levels (1,500–24,400 μatm). Dominant meiofauna taxa remained unaffected in abundance. Densities of calcifying meiofauna taxa (i.e. Gastropoda and Ostracoda) decreased in high CO2 treatments (>6,600 μatm), while the non - calcifying Gastrotricha significantly increased in abundance at 24,400 μatm. In addition, microbial community composition was altered at the highest pCO2 level. We conclude that strong CO2 leakage can alter benthic infauna community composition at multiple trophic levels, likely due to high mortality of the dominant macrofauna species C. edule.

Highlights

Of a continuous diffuse seepage up to >− 1 .0 pH units in a continuous point source leakage scenario[7,8]
Non-calcifying, infaunal invertebrates with a low mobility and bacterial communities are naturally exposed to large fluctuations of pore water pH and pCO221,22, and are likely to be more tolerant to high pCO2 (OA)[13]
Since the burrowing activity of e.g. echinoderms has a strong influence on the biogeochemistry of sediments and the composition of meiofauna communities[25], it seems likely that changes in macrofauna abundance in response to elevated seawater pCO2 can have strong repercussions on infaunal ecosystem processes[23,24]

Summary

Introduction

Of a continuous diffuse seepage up to >− 1 .0 pH units in a continuous point source leakage scenario[7,8]. Studies that have investigated the influence of elevated seawater pCO2 on benthic organisms primarily used short- to medium-term exposures, single species experiments and pCO2 levels relevant for ocean acidification (OA) forecasts. The general response of animals to hypercapnia is related to disturbance and regulation of the intra- and extracellular acid-base balance[13,14,15] Those processes are energy consuming and can result in growth reduction, decreased metabolic activity, low reproduction rates, behavioural changes or death[13,16,17]. Since the burrowing activity of e.g. echinoderms has a strong influence on the biogeochemistry of sediments and the composition of meiofauna communities[25], it seems likely that changes in macrofauna abundance in response to elevated seawater pCO2 can have strong repercussions on infaunal ecosystem processes[23,24]. Bivalves are of high ecological importance as they represent the defining macrobenthic organisms in these habitats, with a key nutritional role for many fish and migratory bird species[26,27]

Methods

Results

Conclusion