The sandeel is one of the most important prey species for puffins – adults and chicks alike. This parent is heading back to the nest with a nice load. Photo © Tycho Anker-Nilssen.
Old harvest data prove useful
The current warming of the oceans has been shown to have detrimental effects for a number of species. An understanding of the underlying mechanisms may be hampered by the non-linearity of the relationships between temperature and demography, and by the insufficient lengths of available time series. Most demographic time series are too short to enable studies of the effects of climate on wildlife in the classical sense of meteorological patterns over at least 30 years. The study highlighted here presents a chick harvest time series of Atlantic puffins that goes back as far as 1880. The data are from the world's largest puffin colony, in southwest Iceland, which has recently experienced a strong decline.
Correlation with ocean temperature via prey
By estimating an annual chick production index over 128 years from the harvest data, the researchers found prolonged periods of strong correlations between local sea surface temperature (SST) and chick production. The study identified an optimal sea temperature of around 7°C for puffin reproduction that may represent the optimal conditions for the survival and reproduction of the puffin’s main prey, the lesser sandeel Ammodytes marinus. A positive or negative deviation from this optimal temperature by 1o C reduces puffin reproduction success by 55 %. This explains the non-linearity in the relation between SST and puffin reproduction.
Explains earlier and ongoing population changes
Through their analyses, the researchers were able to document an Arctic warming period that started around 1920 and lasted for 20 years. During this period, there was a large drop in puffin chick production, and few studies have detected similar effects of climate change that far back in time. The study emphasizes the importance of long time series and indicates that the ongoing decline of the Atlantic puffin population is, at least in part, caused by increasing ocean temperatures around Iceland.
Read the article: Centennial relationships between ocean temperature and Atlantic puffin production reveal shifting decennial trends
Contact: Kjell Einar Erikstad