New study done by the ecologists from Woods Hole Oceanographic Institution in the US and the French National Center for Scientific Research (CNRS) claims that the ever increasing surface temperatures of seas are threatening the survival of juvenile albatross which is leading to a significant reduction in population growth. The study, which was published recently in The British Ecological Society’s Journal of Animal Ecology focused on a specific population of black-browed albatross that are found on the Kerguelen Island, a part of the French Southern and Antarctic Lands. 200 breeding pairs from this population have been extensively studied annually since the year 1979. These black-browed albatrosses, which have a wingspan of approximately 2.5 meters, breed on the island during the austral summer with eggs that were laid in October hatching in December. The younglings develop young feathers around March.
Since the research team was aware that changes in the climate affect seabird species in complicated ways, therefore for this study the team developed a “matrix population model that takes account of the combined effects of climate variables and functional traits in order to understand the entire life cycle and how population growth may be affected in light of a changing climate”. Functional traits are those traits that define species in terms of their interaction with the environment and with other species. Body size, time of breeding and foraging behavior- all three affect the survival and reproduction of the species. Scientists found out that the biggest impact on the population growth was being caused by the changes in the temperature of the sea surface during the late winter, especially on juvenile albatrosses during their first year at sea. Dr Stéphanie Jenouvrier, a seabird ecologist at Woods Hole Oceanographic Institution said, “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.”
The results of the research show that not just the change in climate but the combined effect of climate change over different seasons, functional traits and demographic processes have an effect on the changes in the population of the albatrosses. The juvenile phase and wintering seasons of migratory species, both periods being extremely understudied- also have a significant effect on the size of the population, and are also quite important periods of the said species. Dr Christophe Barbraud of CNRS, co-author of the study said, “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.”