Melting Arctic ice caused by climate change is fuelling the spread of a deadly virus that is wiping out seals, otters and sea lions, new research has revealed.
Phocine distemper virus (PDV) has plagued marine mammals for decades, killing thousands of European harbour seals in the North Atlantic on 2002.
Two years later, it was discovered that northern sea otters in Alaska had contracted the virus.
Researchers were confused about how it could have spread between the species, as they had no contact, due to Arctic sea ice blocking any routes between them.
The phocine distemper virus was found to have spread from European harbour seals in the North Atlantic to sea lions and other marine mammals in the North Pacific. Researchers say this was likely due melting arctic sea ice opening up passages between the two oceans
Now a research team from UC Davis School of Veterinary Medicine has discovered that infected seals from Europe were travelling through passages along Northern Russia and Northern California that had been opened up by lower sea ice levels.
This ‘historic’ change in sea ice may have allowed Arctic and sub-Arctic seals to meet in a way that would not have been possible before.
The team behind the study found this was the likely cause of the introduction of PDV into the North Pacific Ocean.
Researchers spent 15 years studying the spread of PDV between marine mammals in the North Atlantic and marine mammals in the North Pacific. They discovered that there was an increase in cases in North Pacific species when the arctic sea ice was particularly thin
Dr Tracey Goldstein, from UC Davis and the author of a study into the spread of the virus said: ‘The loss of sea ice is leading marine wildlife to seek and forage in new habitats and removing that physical barrier, allowing for new pathways for them to move.
‘As animals move and come in contact with other species, they carry opportunities to introduce and transmit new infectious disease, with potentially devastating impacts.’
Dr Goldstein and colleagues investigated the timing of the introduction of PDV into the North Pacific, the risk factors associated with its emergence and patterns of transmission.
Researchers from UC Davis School of Veterinary Medicine, which provided the data used in this image, used satellite data to help link animal movement and risk factor data. They used this information to demonstrate that exposed animals could carry PDV long distances
The team used data on PDV exposure and infection in a number of marine mammals including ice seals, steller sea lions, northern fur seals and sea otters in producing the study. They also made use of animal movement data collected between 2001 and 2016.
They found there was widespread infection and exposure to the virus across the North Pacific Ocean starting in 2003. This peaked again in 2009 and coincided with reductions in Arctic sea ice.
A study by researchers from the University of Cincinnati earlier in 2019 found that the Arctic could soon be completely free of sea ice during its transition from summer to winter, due to climate change.
Ice in the Arctic fluctuates greatly along a seasonal cycle, but rising global temperatures have driven dramatic changes in the area.
‘The target is the sensitivity of sea ice to temperature,’ says Won Chang, a study co-author and UC assistant professor of mathematics.
‘What is the minimum global temperature change that eliminates all Arctic sea ice in September? What’s the tipping point?’
According to the Cincinnati team, that tipping point could be as low as just 2 degrees of warming.
Dr Goldstein and her team used satellite data to help link animal movement and risk factor data. They used this information to demonstrate that exposed animals have the potential to carry PDV long distances.
Elizabeth VanWormer, an author on the research paper said the problem of viruses spreading between the North Atlantic and North Pacific, as well as changes in marine mammal behaviour will only get worse as the ice continues to melt.
‘As sea ice continues its melting trend, the opportunities for this virus and other pathogens to cross between North Atlantic and North Pacific marine mammals may become more common,’ she said
‘This study highlights the need to understand PDV transmission and the potential for outbreaks in sensitive species within this rapidly changing environment.’
The outbreak of PDV in 2002 wasn’t the first time it had caused fatalities in the European marine mammal population.
In 1988 more than 18,000 animals were killed as a result of a PDV outbreak including 60% of the UK harbour seal population.
In 2003 marine mammals in the North Pacific Ocean were found to be infected with PDV for the first time. This prompted the 15 year study led by Dr Goldstein at the UC Davis School of Veterinary Medicine.
WHAT ARE THE EFFECTS OF LOWER SEA ICE LEVELS?
The amount of Arctic sea ice peaks around March as winter comes to a close.
NASA recently announced that the maximum amount of sea ice this year was low, following three other record-low measurements taken in 2015, 2016 and 2017.
This can lead to a number of negative effects that impact climate, weather patterns, plant and animal life and indigenous human communities.
The amount of sea ice in the Arctic is declining, and this has dangerous consequences, NASA says
Additionally, the disappearing ice can alter shipping routes and affect coastal erosion and ocean circulation.
NASA researcher Claire Parkinson said: ‘The Arctic sea ice cover continues to be in a decreasing trend and this is connected to the ongoing warming of the Arctic.
‘It’s a two-way street: the warming means less ice is going to form and more ice is going to melt, but, also, because there’s less ice, less of the sun’s incident solar radiation is reflected off, and this contributes to the warming.’
Source : Google News