http://www.sciencedirect.com/science/article/pii/S1750583615000109

International Journal of Greenhouse Gas Control
Available online 27 February 2015, doi:10.1016/j.ijggc.2015.01.003

Impact of sub-seabed CO2 leakage on macrobenthic community structure and
diversity

Stephen Widdicombe
Caroline Louise McNeill
Karen Tait

Highlights
• Sub-seabed release of CO2 reduced macrofaunal diversity, abundance and
biomass.
• Impacts were only detectable in the area of active CO2 leakage, primarily
where bubbling was observed.
• Community recovery was rapid once leakage had stopped.
• Natural seasonal variability was seen in reference areas with additional
evidence of natural disturbances (storms).

Abstract
A sub-seabed release of carbon dioxide (CO2) was conducted to assess the
potential impacts of leakage from sub-seabed geological CO2 Capture and
Storage CCS) on benthic macrofauna. CO2 gas was released 12 m below the
seabed for 37 days, causing significant disruption to sediment carbonate
chemistry. Regular macrofauna samples were collected from within the area
of active CO2 leakage (Zone 1) and in three additional reference areas, 25
m, 75 m and 450 m from the centre of the leakage (Zones 2, 3 and 4
respectively). Macrofaunal community structure changed significantly in all
zones during the study period. However, only the changes in Zone 1 were
driven by the CO2 leakage with the changes in reference zones appearing to
reflect natural seasonal succession and stochastic weather events. The
impacts in Zone 1 occurred rapidly (within a few days), increased in
severity through the duration of the leak, and continued to worsen after
the leak had stopped. Considerable macrofaunal recovery was seen 18 days
after the CO2 gas injection had stopped. In summary, small short-term CCS
leakage events are likely to cause highly localised impacts on macrofaunal
communities and there is the potential for rapid recovery to occur,
depending on the characteristics of the communities and habitats impacted.

Keywords
CCS
Biological impact
Monitoring
Environmental baseline
Controlled release experiment

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