Impacts likely to ripple through Arctic ecosystem
LINZ — Global warming is likely to lead to bigger and badder Arctic mosquito swarms, according to a new Dartmouth College study. Already, warming temperatures are causing Arctic mosquitoes to grow faster and hatch earlier, significantly boosting their population and threatening caribou.
The study predicts the mosquitoes’ probability of surviving and emerging as adults will increase by more than 50 percent if Arctic temperatures rise 2 degrees Celsius. Changes in the timing and intensity of mosquito emergence will have a ripple effect on other parts of Arctic ecosystems, including Arctic and migratory birds.
“Increased mosquito abundance, in addition to northward range expansions of additional pest species, will have negative consequences for the health and reproduction of caribou,” said lead author Lauren Culler, a postdoctoral researcher at Dartmouth’s Dickey Center’s Institute of Arctic Studies.
Average temperatures in the Arctic have increased at twice the global rate in the past 100 years, and the low biodiversity of Arctic ecosystems provided a simple predator-prey interaction for this study. Arctic mosquitoes develop in shallow temporary ponds of springtime snowmelt on the tundra, where their top predators are diving beetles.
The researchers studied the response of mosquitoes to warming in filed and lab studies in western Greenland, then built a computer model to project how those changes will play out over their life cycle, from birth to adult feeding stage, under a range of temperatures in future climate change scenarios for the Arctic.
The results show that warmer spring temperatures caused the mosquitoes to emerge two weeks early and shortened their development time through the larval and pupal stages by about 10 percent for every 1 degree Celsius increase in temperature.
Warming increased the number of mosquitoes being eaten by diving beetles, their main predators. But the vulnerable, juvenile mosquitoes also grew faster; reducing their exposure to predators and increasing their chance of surviving to adulthood. With 2 degrees of warming, the mosquitoes’ probability of survival will increase by 53 percent.
Arctic mosquitoes’ reproductive success depends on the females finding a blood meal, which is expected to increase because warming more closely synchronizes their life cycle with caribou calving. The calving season benefits mosquitoes by giving them a larger, less mobile herd to feed on, including vulnerable calves.
The researchers say the climate-population model they developed for Arctic mosquitoes and their predators can be generalized to any ecosystem where survival depends on sensitivities to changing temperatures.
The study appears in the journal Proceedings of the Royal Society B: Biological Sciences.