USGS Links 10 Alaska Streams' Thawing Permafrost to Weaker Arctic Fish
Updated
Updated · Sciworthy · Aug 19
USGS Links 10 Alaska Streams' Thawing Permafrost to Weaker Arctic Fish
3 articles · Updated · Sciworthy · Aug 19
Summary
A USGS study of 10 headwater streams in Alaska's Brooks Range found areas with more permafrost had warmer water, fewer Dolly Varden, and Arctic Grayling with lower energy density.
Warmer streams appeared to push fish beyond their optimal temperature range because permafrost limited groundwater infiltration that would otherwise cool the water.
That same limited infiltration sent rainfall straight into streams, causing rapid rises and falls in water levels; fish in those unstable streams also showed lower energy density.
Higher dissolved organic carbon and phosphorus in more permafrost-heavy areas boosted biofilms, which supported more macroinvertebrates and greater Dolly Varden biomass through a bottom-up food-web effect.
The findings add to evidence that the Arctic—warming about 4 times faster than the global average—could see freshwater ecosystems reshaped as thawing permafrost alters stream conditions.