Phoebe Lehmann Zarnetske '01

 

line in the sand

Phoebe Lehmann Zarnetske '01
Phoebe Lehmann Zarnetske '01
To most of us, it’s just beach grass. To Phoebe Zarnetske ’01, it may be changing the contour of our coasts.

For the last two years, Zarnetske has studied invasive beach grasses while working towards her doctorate in zoology at Oregon State. Ammophila arenaria, European beach grass, has been introduced all over the world to provide coastal protection from storm surge. Ammophila breviligulata, American beach grass, is native to the East Coast and Great Lakes and was introduced in 1935 to stabilize sand at the mouth of the Columbia River. Since then, American beach grass has slowly spread north into Canada, and Zarnetske recently documented its spread south to Oregon’s central coast.

She also has noticed drastic changes in dune structure on the Pacific coast. Native dune systems were originally low-lying, open systems before European beach grass added a large, stable “foredune,” the area directly behind a beach. Zarnetske hypothesizes that the recent spread of American beach grass gradually modifies these dunes by creating a lower foredune.

How will this series of introductions change native dune structure and influence existing
ecosystems?

To address this question Zarnetske models the effects of the dune-building grasses. She places planters containing varying quantities of the two introduced grass species and native beach grass in a wind tunnel at the O.H. Hinsdale Wave Research Laboratory and exposes them to different amounts of sediment. From this, she evaluates how much sand each species can capture and relates it to the type and abundance of grass. Eventually Zarnetske’s data will feed a larger predictive model of dune formation.

As we continue to engineer and shape—and reshape— the world around us, Zarnetske wants to understand what the effects will be. She hopes to have some influence on management and land-use policies through her ecological models, which she calls an “abstraction of the truth as best we can understand it.”

Chad G. Sisson ’96