Impact of elevated levels of CO2 on animal mediated ecosystem function: The modification of sediment nutrient fluxes by burrowing urchins.

Widdicombe, S., Beesley, A., Berge, J. A., Dashfield, S. L., McNeill, C. L., Needham, H. R. and Øxnevad, S. (2013) Impact of elevated levels of CO2 on animal mediated ecosystem function: The modification of sediment nutrient fluxes by burrowing urchins. Marine Pollution Bulletin, 73 (2). pp. 416-427. DOI 10.1016/j.marpolbul.2012.11.008.

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Abstract

A mesocosm experiment was conducted to quantify the relationships between the presence and body size of two burrowing heart urchins (Brissopsis lyrifera and Echinocardium cordatum) and rates of sediment nutrient flux. Furthermore, the impact of seawater acidification on these relationships was determined during this 40-day exposure experiment. Using carbon dioxide (CO2) gas, seawater was acidified to pHNBS 7.6, 7.2 or 6.8. Control treatments were maintained in natural seawater (pH ≈ 8.0). Under normocapnic conditions, burrowing urchins were seen to reduce the sediment uptake of nitrite or nitrate whilst enhancing the release of silicate and phosphate. In acidified (hypercapnic) treatments, the biological control of biogeochemical cycles by urchins was significantly affected, probably through the combined impacts of high CO2 on nitrifying bacteria, benthic algae and urchin behaviour. This study highlights the importance of considering biological interactions when predicting the consequences of seawater acidification on ecosystem function.
Highlights:
► At pH8, urchins reduced sediment uptake of NOx and increased the release of silicate and phosphate. ► Reduced pH significantly affected the relationship between urchins and sediment nutrient fluxes. ► CCS leaks could alter nutrient cycling by disrupting key animal–microbial relationships.

Document Type: Article
Keywords: Bioturbation; Carbon capture and storage; Ocean acidification; Ecosystem function; Nutrient cycling
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.marpolbul.2012.11.008
ISSN: 0025-326X
Projects: ECO2
Date Deposited: 28 May 2014 08:42
Last Modified: 28 May 2014 08:42
URI: http://oceanrep.geomar.de/id/eprint/24644

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