Monday, 4 August 2008

Seabirds Sensitive to Local Impacts of Climate Change

A paper published recently in the journal Global Change Biology, has shown how local impacts of climate change affect seabird populations of the common guillemot Uria aalge and the thick-billed guillemot Uria lomvia around the Northern Hemisphere.

Climate change may alter the frequency, intensity and distribution of the climatic indices; the North Atlantic Oscillation, the Pacific Decadal Oscillation and the Arctic Oscillation. These climatic oscillations are linked to sea surface temperature (SST), which in turn affects the prey abundance for seabirds.

In this study, data were collected and analysed from 43 different colonies across the whole circumpolar region. Colonies where factors other than climate were known to have a great impact on guillemot populations, (such as excessive hunting and oil spills) were excluded from the study so as not to confound the results. Whereas previous studies had focused on effects of climate change on seabird populations at single locations, the strength of this study lies in the extent of area covered; most of the Northern Hemisphere. Looking at such a large geographic area greatly minimises the possibility that observed changes could have been caused by anything other than climate change. SST datasets were taken from three time-series, 1965-76, 1977-88 and 1989-97. SST was described as the temperature deviation (positive or negative) from a 50-year average around guillemot colonies.

The researchers discovered that both species responded negatively to rapid changes in the environment, regardless of how the temperature changed. However, common guillemots responded favourably to colder phases (that is, an increase in colder, energy-rich waters) and thick-billed guillemots favoured warmer phases (since they are found further north and warmth allows ice melt and greater feeding opportunities). The response to rapid change reinforces the idea that broadly, even within an ecological time frame, species with a slow life-history strategy particularly cannot adapt fast enough to rapid environmental change.

The wider implications for biodiversity, and thus for conservation managers and policy-makers, is once again a strengthening of measures to tackle climate change. Although conservation measures can be implemented for biodiversity at mid-latitudes to help local adaptation, species already at northern latitudes cannot readily shift their climatic envelopes. Hence globally, we must increase efforts to reduce the rate at which we are changing our climate.

Reference:

Irons, D., Tycho, A-N., Gaston, A.J. et al. (2008). Fluctuations in circumpolar seabird populations linked to climate oscillations. Global Change Biology. 14(7):1455-1463.

Read the full paper online here (subscription required).

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