Researchers are discovering that an uncommon disease epidemic in Antarctic fish may be caused by climate change. John Postlethwait and Thomas Desvignes, two scientists from the University of Oregon, have been traveling to the West Antarctic Peninsula for ten years.
A new study suggests warming water in the Antarctic may be behind a disease outbreak in icefish. Image Credit: University of Oregon.
Scientists investigate a particular kind of fish that has evolved to survive in the severe arctic climate. However, on a field trip in 2018, they discovered an unusual phenomenon: several of the fish had terrible skin tumors.
Together with virologists and pathologists, they came to the conclusion that the tumors were caused by an epidemic of parasitic diseases of a magnitude never before seen close to Antarctica. The epidemic in this especially sensitive habitat may have been influenced by warming seas and melting ice, according to research funded by the US National Science Foundation and published in iScience.
When life conditions become challenging, animals become more prone to disease.
Thomas Desvignes, Study Lead Author, Institute of Neuroscience, University of Oregon
The majority of fish found in the icy seas close to Antarctica belong to a class of fish known as notothenioid, or icefish. Notothenioid have developed particular proteins that keep their blood from freezing as one of their many adaptations to their icy environment.
The scientists traveled to a tiny fjord on the West Antarctic Peninsula during the 2018 field season, which is typically covered in ice at that time of year. When they saw it was clear, they entered and started fishing.
As soon as we got the first trawl back on deck, we realized that one species was abundant, and a lot of them had big tumors.
Thomas Desvignes, Study Lead Author, Institute of Neuroscience, University of Oregon
Both healthy and diseased fish samples were gathered by him and his team, who then sent them back to Oregon. The researchers had been fishing in Antarctica for years, but they had never seen a disease of that magnitude. Neither had many other fish scientists who were acquainted with the region in Antarctica.
The researchers examined the tumors in the lab. The diagnosis was X-cell disease, a parasitic condition that is not well understood. Although it has sometimes been seen in Iceland and Norway wild fisheries, experts are unsure of how it is spread.
Desvignes hypothesized that fish may be under stress from warming waters and changing habitats, making them more susceptible to disease.
Maria Vernet, a program director in NSF’s Office of Polar Programs, “This study is evidence of how much there is to discover in Antarctica. Although notothenioids are the most studied fishes in the region due to their evolutionary adaptations, sampling in a new location has provided a completely new picture of fish parasitism.”
Journal Reference:
Desvignes, T., et al. (2022) A parasite outbreak in notothenioid fish in an Antarctic fjord. iScience. doi.org/10.1016/j.isci.2022.104588.