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

A rapid increase in the frequency of icebergs pounding the shallow seafloor around the West Antarctic Peninsula – as a result of shrinking winter sea ice – has caused the life expectancy of a tiny marine creature (bryozoans) to halve over the last 12 years. This is the first evidence of regional climate warming affecting marine animals living on the Southern Ocean seabed. The results are published in the journal Nature Climate Change.

The paper describes how colonies of bryozoans (Fenestrulina rugula) – one of the most abundant animals in the shallows around Rothera Research Station – are unable to recover from frequent iceberg scouring. Twelve years ago colonies could live to five years old but now they rarely reach two or three years of age – and most die before they are able to reproduce. Seabed life, such as bryozoans, may be an important carbon sink in the Southern Ocean, and their early deaths could signal wider, severe consequences on the whole ecosystem, with more carbon being released back into the sea.

The researchers examined concrete markers showing the rate of iceberg scouring – placed on the seabed by BAS divers – as well as bryozoan-encrusted rocks situated nearby. In addition, collections of historical records of winter sea ice (called fast ice) around Rothera Research Station show a clear link between fast-ice loss and impacts on experimental markers on the seabed. It’s likely that iceberg scouring has similarly increased in other areas of winter sea ice loss, which means that increasing mortality of sea bed creatures could become widespread.

Link to the full paper in the NERC Open Research Archive

 

Authors

Barnes, D. K. A., Souster, T. 2011

Publication

Nature Climate Change Online, 365-368