Invasive insect tied to shrinking river

By coating and killing eastern hemlock trees, woolly adelgids (white) can also alter the flow of rivers, a study says.

Nicholas A. Tonelli/Wikimedia Commons (CC BY 2.0)

Guest post by Nsikan Akpan

Rivers bully bugs, pushing them to and fro, but the invasive hemlock woolly adelgid is exacting revenge.

After an adelgid outbreak decimated eastern hemlock trees along a headwater stream in North Carolina, researchers expected river surges. Eastern hemlock trees live along riverbeds, sopping up water from the soil year-round, so fewer hemlocks should mean more water seeping into streams.

Instead, the watershed shrank, with its annual flow dropping by 8 percent in less than decade, scientist report June 7 in Ecohydrology. The team expects the decline to continue as rhododendrons and other replacement vegetation that sap more water from the ground than hemlocks take over the vacant land.

More Stories from Science News on Ecosystems