Impact of elevated levels of CO2 on animal mediated ecosystem function: The modification of sediment nutrient fluxes by burrowing urchins |
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Authors: | S Widdicombe A Beesley JA Berge SL Dashfield CL McNeill HR Needham S Øxnevad |
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Institution: | 1. Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth PL1 3DH, United Kingdom;2. Norwegian Institute for Water Research, Gaustadalléen 21, NO-0349 Oslo, Norway;3. Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton, New Zealand |
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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. |
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Keywords: | Bioturbation Carbon capture and storage Ocean acidification Ecosystem function Nutrient cycling |
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