Abstract
Atmospheric CO2 emissions are a global concern due to their predicted impact on biodiversity, ecosystems functioning, and human life. Among the proposed mitigation strategies, CO2 capture and storage, primarily the injection of CO2 into marine deep geological formations has been suggested as a technically practical option for reducing emissions. However, concerns have been raised that possible leakage from such storage sites, and the associated elevated levels of pCO2 could locally impact the biodiversity and biogeochemical processes in the sediments above these reservoirs. Whilst a number of impact assessment studies have been conducted, no information is available on the specific responses of viruses and virus–host interactions. In the present study, we tested the impact of a simulated CO2 leakage on the benthic microbial assemblages, with specific focus on microbial activity and virus-induced prokaryotic mortality (VIPM). We found that exposure to levels of CO2 in the overlying seawater from 1,000 to 20,000 ppm for a period up to 140 days, resulted in a marked decrease in heterotrophic carbon production and organic matter degradation rates in the sediments, associated with lower rates of VIPM, and a progressive accumulation of sedimentary organic matter with increasing CO2 concentrations. These results suggest that the increase in seawater pCO2 levels that may result from CO2 leakage, can severely reduce the rates of microbial-mediated recycling of the sedimentary organic matter and viral infections, with major consequences on C cycling and nutrient regeneration, and hence on the functioning of benthic ecosystems.
Highlights
Atmospheric CO2-induced impact on virus–host interactionsCarbon dioxide (CO2) emissions are driving ocean warming and acidification with consequences for marine biodiversity and ecosystem functioning
We investigated the impact of CO2-enriched seawater plumes originated by possible CO2 leakages on benthic prokaryotic metabolism and virus–host interactions according to a putative gradient of CO2 concentration
Previous studies conducted on the impact of CO2 leakage on microbial components revealed the presence of significant shifts in the abundance of different microbial components either in the
Summary
Atmospheric CO2 emissions are driving ocean warming and acidification with consequences for marine biodiversity and ecosystem functioning. The effects of CO2 leaking from subseafloor reservoirs on the marine environment includes localized seawater and sediment acidification as well as a number of changes in other physical–chemical properties (Gehlen et al, 2011; Lichtschlag et al, 2014; Queirós et al, 2014; RodríguezRomero et al, 2014), many of which have been shown to alter benthic assemblages and biogeochemical processes (Laverock et al, 2013; Widdicombe et al, 2013, 2015; Tait et al, 2014) These studies have highlighted a variety of responses amongst different species and taxa, depending on the local hydrodynamic regime, and the duration/extent of the leakage (de Vries et al, 2013; Widdicombe et al, 2013; Blackford et al, 2014). A number of uncertainties still surround efforts to predict the impact of leakage from CCS, and this limits our ability to evaluate costs vs. benefits and to make final decisions about the suitability of the CCS approach (de Vries et al, 2013)
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