According to a recent study, sudden change in sea surface temperature affects the survival of black-browed albatross of Kerguelen Island.
The researchers found that changes in sea surface temperature during late winter cause the biggest variations in the population growth rate, through their impact on juvenile survival during their first year at sea.
“Sea surface temperature is widely used as an indicator of food availability for marine predators because warmer temperatures usually result in lower primary productivity in marine ecosystems, ultimately reducing the availability of prey”, said Dr Stephanie Jenouvrier.
The effects of climatic conditions on seabirds generally occur indirectly and in complex ways. In this study, the researchers have found out that functional traits such as body size, timing of breeding, and foraging behaviour all have an impact on demographic traits such as survival and reproduction.
“As our oceans are projected to warm, fewer juvenile albatrosses will manage to survive and populations are expected to decline at a faster rate,” she added.
Among the functional traits, the researchers found that foraging behaviour during the pre-breeding period has a major impact on the population growth rate. For a population of individuals spending a high proportion of their time on the water, with few take-offs and landings, the population growth rate is projected to decline up to 5.3% per year.
The results suggest that changes in population size and structure are driven by the combined effects of climate over various seasons, multiple functional traits and demographic processes across the full life cycle of black-browed albatross.
The study also unravelled the important role of the juvenile phase and wintering season, two understudied parts of the life cycle of this migratory species.
“Albatrosses and other seabirds are long-lived predators that fly very long distances to forage at sea and nest on land. As a key indicator of ecosystem health, studying how seabirds fare in the face of climate change can help us predict the ecological impacts on the entire marine food web”, concluded Dr Christophe Barbraud
Around 200 breeding pairs have been monitored annually since 1979 for this research.
Reaching a wingspan of 2.5 metres, black-browed albatrosses breed on these Sub-antarctic Islands during the austral summer, laying a single egg in October that will hatch in December. The chicks fledge in late March at a size similar to that of an adult.
The studies appear in Journal of Animal Ecology.