(MENAFN- AzerNews)
By Alimat Aliyeva
The large-scale warming of surface waters in the Northeastern
Pacific Ocean in 2014-2016, known as the "warm blob," caused
catastrophic consequences for marine ecosystems. One of the most
affected groups was seabirds, particularly thin-billed kittiwakes,
predators that depend on the availability of small fish,
Azernews reports.
A study conducted by the U.S. Fish and Wildlife Service and
published in the journal Science showed that about 4 million
kittiwakes died during the heatwave, which is half of their
population in Alaska. An analysis of data from 13 colonies,
covering the period from 2008 to 2022, revealed a sharp decline in
the number of birds.
In the Gulf of Alaska, the number of birds decreased by 50
percent. In the eastern part of the Bering Sea, losses amounted to
75 percent.
Before the "warm blob," about 8 million kittiwakes lived in
Alaska, a quarter of the world population. Today, their number has
fallen to 4 million, and no recovery has been recorded over the
past seven years.
Scientists have found that the main factor in the death of the
birds was not heat stress, but drastic changes in the food chain.
The warming of the ocean led to a decrease in ecosystem
productivity, which caused a shortage of fish, a key food source
for kittiwakes. Analysis of the birds' remains showed that most of
them died of starvation.
"These results clearly demonstrate the long-term effects of the
marine heatwave on marine predators," said Julia Parrish, a
professor at the University of Washington and co-author of the
study.
Although the "blob" became one of the strongest marine
heatwaves, such phenomena are becoming more frequent due to climate
change. A 2023 study, in which many of the authors of this work
participated, showed that an increase in ocean surface water
temperature of just 1°C over six months can cause mass deaths of
seabirds.
"The frequency and intensity of such events increase with ocean
warming. We may be at a stage where the ecosystem is being rebuilt,
and a return to the previous state may not be possible," said
Parrish.
The recovery of seabird populations after a heatwave usually
takes about three years, but the kittiwakes in Alaska show no signs
of population growth even after seven years. This raises concerns
among scientists and raises questions about the future
sustainability of marine ecosystems.
Participants in the University of Washington's Citizen Science
program made a significant contribution to data collection.
Volunteers living on the coasts helped record cases of mass bird
deaths, which became an important source of information for
analysis.
The authors of the study emphasize that the preservation of
marine ecosystems requires not only monitoring but also active
measures to reduce the effects of climate change to prevent further
disasters.
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