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Reduced survival of Antarctic benthos linked to climate-induced iceberg scouring

Nature Climate Change volume 1, pages 365368 (2011) | Download Citation

Abstract

The West Antarctic Peninsula (WAP) is a hotspot of recent rapid regional warming and ice loss1. The WAP sea surface freezes each winter to form a ‘fast-ice’ skin that can reduce iceberg drift and collisions between their keels and the sea bed, in what is termed scouring. Scouring disturbance is thus inversely correlated with fast-ice duration2. We examined long-term records of fast ice, ice scour and mortality of benthos around Rothera research station (WAP) to determine whether there is a biological response from the sea bed coincident with fast-ice changes. Here we show that the duration of fast ice at Rothera has significantly decreased by >5 d yr−1 over 25 years and that this is strongly correlated with increased ice scour and mortality of benthos in the shallows. The number of experimental markers at Rothera crushed by iceberg scouring increased over the past decade. We found that survival of one of the most common shallow species3, the bryozoan Fenestrulina rugula, is linked to ice-scour frequency and has markedly decreased over the past 12 years. The chance of colonies reaching two years old, the age at which they typically begin to sexually reproduce, has halved since 1997. These findings suggest that increased scouring of the sea bed has led to higher benthic mortality, with implications for the region’s biodiversity.

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Acknowledgements

We thank all recorders of fast-ice conditions from 1986 to 2010 and drivers of the Rothera Time Series, A. Clarke and M. Meredith. We also thank diving staff that have participated in the ice-scour project since its inception and remember K. Brown, who died in pursuit of understanding ice scour and its influence on seabed biology. Finally, we thank M. Eléaume for very helpful comments leading to a better manuscript.

Author information

Affiliations

  1. British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB3 0ET, UK

    • David K. A. Barnes
    •  & Terri Souster

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Contributions

Project planning, fast-ice duration and biological data collection, data analysis, writing—D.K.A.B. Diving surveys, fast-ice duration and ice-scour data collection—T.S.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to David K. A. Barnes.

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DOI

https://doi.org/10.1038/nclimate1232

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