Marine ecosystems are highly intertwined and disturbance to just one of the species in the entire chain could have a knock-on and detrimental effect on other marine animals. This is exactly what has happened in the case of seabirds as a new study by University of British Columbia researchers have found that since 1950s, seabird populations have dropped 70 per cent.
Michelle Paleczny, a UBC master’s student and researcher with the Sea Around Us project, and co-authors collected and analysed information on more than 500 seabird populations from around the world representing 19 per cent of the global seabird population.
They found that the overall populations had declined by 69.6 per cent in matter of 60 years and this translates to loss of a whopping 230 million birds at the rate of nearly 4 million birds a year.
Researchers revealed that this dynamic decline is a direct results of a number of factors including overfishing of the fish that seabirds rely on for food; plastic and oil pollution; destruction and changes to seabird habitat; introduction of non-native predators to seabird colonies; and environmental and ecological changes caused by climate change.
Seabirds tend to travel the world’s oceans foraging for food over their long lifetimes, and return to the same colonies to breed. Colony population numbers provide information to scientists about the health of the oceans the birds call home.
Albatross, an iconic marine bird that lives for several decades, were part of the study and showed substantial declines. Paleczny says these birds live so long and range so far that they encounter many dangers in their travels. A major threat to albatross is getting caught on longline fishing hooks and drowning, a problem that kills hundreds of thousands of seabirds every year.
“Seabirds are particularly good indicators of the health of marine ecosystems,” said Paleczny. “When we see this magnitude of seabird decline, we can see there is something wrong with marine ecosystems. It gives us an idea of the overall impact we’re having.”
“Our work demonstrates the strong need for increased seabird conservation effort internationally,” said Paleczny. “Loss of seabirds causes a variety of impacts in coastal and marine ecosystems”
Seabirds play an important role in those ecosystems. They eat and are eaten by a variety of other marine species. They also transport nutrients in their waste back to the coastal ecosystems in which they breed, helping to fertilize entire food webs.
The study, published in PLOS ONE, is the first to estimate overall change in available global seabird population data. It is a collaboration between UBC researchers Paleczny, Vasiliki Karpouzi and Daniel Pauly and Edd Hammill, a lecturer at the University of Technology, Sydney in Australia.