- New research finds that increased sea surface temperatures can affect the survival of juvenile albatross during their first year at sea and lead to reduced population growth rates.
- Ecologists in the US and France examined how climate change and functional traits — attributes like body size and foraging habits that define a species’ role in the broader ecosystem — impact population dynamics of the black‐browed albatross (Thalassarche melanophris) by studying 200 breeding pairs of the long‐lived, migratory seabirds at Kerguelen Island in the southern Indian Ocean.
- Changes in sea surface temperature during the breeding season were found to have little impact on black-browed albatross population growth rates, but higher sea surface temperatures in late winter did have a significant impact because of their effect on the survival of juveniles, according to the study.
New research finds that increased sea surface temperatures can affect the survival of juvenile albatross during their first year at sea and lead to reduced population growth rates.
Ecologists with the Woods Hole Oceanographic Institution (WHOI) in the US and France’s National Center for Scientific Research (CNRS) examined how climate change and functional traits — attributes like body size and foraging habits that define a species’ role in the broader ecosystem — impact population dynamics of the black‐browed albatross (Thalassarche melanophris) by studying 200 breeding pairs of the long‐lived, migratory seabirds at Kerguelen Island in the southern Indian Ocean. Their results were published this week in the Journal of Animal Ecology.
“The effects of climatic conditions on seabirds generally occur indirectly. They operate primarily through effects on the availability of prey and breeding habitats potentially causing changes in transportation costs, timing of breeding and body conditions of seabirds,” the researchers write in the study. That means that phenology (the timing of life events like breeding or migration), body conditions, and foraging behaviors are some of the key functional traits through which seabirds like the black-browed albatross might respond to climate change. These responses, in turn, can have consequences for demographic trends and population dynamics.
Changes in sea surface temperature during the breeding season were found to have little impact on black-browed albatross population growth rates, but higher sea surface temperatures in late winter did have a significant impact because of their effect on the survival of juveniles, according to the study.
“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,” Stéphanie Jenouvrier, a seabird ecologist at WHOI and lead author of the study, explained in a statement. “As our oceans are projected to warm, fewer juvenile albatrosses will manage to survive and populations are expected to decline at a faster rate.”
The researchers also determined that adult black-browed albatross adapt to changes in climate conditions during the winter by altering their migratory schedule, as opposed to their at-sea foraging activities, but that this alteration didn’t have a big impact on population growth rates. Among functional traits, adult’s foraging activity during the pre-breeding period had the biggest effect.
Jenouvrier and her co-authors write in the study that their results “suggest that the population dynamics of [black-browed albatross] are driven by the combined effects of climate over various seasons, multiple functional traits and demographic processes across the full life cycle.” The researchers particularly underscore the importance of studying the bird’s entire life cycle, since black‐browed albatross population dynamics are driven “by processes occurring during multiple seasons (the wintering, pre‐breeding and breeding season) through carry‐over effects, whereby climate or functional traits that affect an individual in one season also affect its demographic rates during a subsequent season.”
For instance, winter climate conditions and foraging activity of adult albatross during the pre-breeding season can have large carry-over effects on breeding success during the next breeding season, the researchers found. They conclude that “Carry‐over effects have potentially large impacts on populations, and it is thus very difficult to draw general conclusions about which season of the life cycle is the most critical for population dynamics without analyses integrating the complete life cycle.”
Christophe Barbraud of CNRS, a study co-author, said that understanding how seabirds like black-browed albatross respond to global warming and changing climatic conditions could help us better anticipate impacts on marine ecosystems as a whole.
“Albatrosses and other seabirds are long-lived predators that fly very long distances to forage at sea and nest on land,” Barbraud said in a statement. “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.”
CITATION
• Jenouvrier, S., Desprez, M., Fay, R., Barbraud, C., et al. (2018). Climate change and functional traits affect population dynamics of a long-lived seabird. Journal of Animal Ecology. doi:10.1111/1365-2656.12827