New research suggests that changing moisture conditions in the Arctic could influence how parasites are transmitted to Svalbard reindeer, highlighting an often overlooked effect of climate change.
A recent field experiment examined the behaviour of Ostertagia gruehneri, a parasitic nematode commonly found in Svalbard reindeer. This parasitic worm has a free-living larval stage that develops outside the host and can be ingested while animals graze.
Researchers investigated how temperature and moisture affect where these infective larvae are located in the tundra environment. This distribution is critical, as larvae found on vegetation are more likely to be consumed by grazing reindeer, while those in the soil are less accessible.
The study found that moisture, rather than temperature, played a key role. Under wetter conditions, significantly more larvae were present on vegetation, where they are more likely to be ingested by grazing reindeer. In contrast, drier conditions were associated with fewer larvae above ground, likely due to reduced movement and increased mortality.
Surprisingly, experimental warming had no measurable effect on larval abundance in either soil or vegetation over the short term. This suggests that, within the tested range, temperature alone may not directly influence how available parasites are to grazing animals.
These findings point to the importance of precipitation and surface moisture in shaping parasite exposure, suggesting that changes in rainfall and snowmelt may be as important as warming itself. As Arctic climates become not only warmer but also wetter and more variable, short-term changes in moisture could lead to fluctuations in infection risk.
Parasites such as O. gruehneri are known to affect the body condition and reproductive success of reindeer. Changes in how and when animals are exposed may therefore have broader implications for population dynamics.
By influencing the interaction between host and parasite, shifting environmental conditions could also affect Arctic ecosystems more widely. The study highlights that understanding climate impacts on wildlife requires looking beyond temperature alone, to include the role of water and local environmental variability in shaping disease risk.
Léa Zinsli, PolarJournal