By Chris Powers
SC Staff Writer
ESU graduate student Katie Barnes defended her graduate thesis last Friday, April 25, in Kurtz Lecture Hall.
This thesis was a defense of her work at ESU over the past three years, which entailed studying Louisiana Waterthrush and aquatic insects in order to gauge the health and productivity of two different types of eastern hemlock forests.
Looking at the health of these ecosystems is important because, according to Barnes, “Riparian habitats support a great diversity of plants and animals and are generally more productive than upland habitats.”
“Unfortunately,” Barnes added, “Our hemlock forests are in decline.”
The woolly adelgid, an invasive insect, parasitizes a tree and causes it to defoliate from the bottom of the tree to the top by sucking out all the sap.
Barnes believes that this is a cause for concern.
“These trees are becoming defoliated, which is changing the microclimates and increasing the temperatures,” she said.
Barnes went on to say, “With the warming of the water, the stream invertebrates are going to be in decline.”
This decline of stream invertebrates can then impact the health of the animals that prey on them, such as the Louisiana Waterthrush.
Barnes’s study focused on eastern hemlock forests along headwater streams, which are small streams that drain into larger bodies of water.
The habitats formed by these streams fall into two different categories, benches and ravines.
Ravines, according to Barnes, are “characterized by steep slopes and fast moving water,” while benches are “flat flood plains with meandering water.”
The ecological integrity of these two types of habitat were looked at and compared.
The Louisiana Waterthrush (LOWA) is a migratory riparian bird that prefers living along headwater streams and may be utilized as a bioindicator for these environments.
Barnes stated, “They are useful in that they are sensitive to water quality and feed on aquatic insects.”
“Their absence is an indicator to poor water quality and poor environmental health,” she continued.
Barnes looked at LOWA pair density, or the number of nesting pairs per kilometer of stream.
She also looked at pairing success, or the number of paired males compared to the total number of males, and reproductive success, or whether or not the birds in question successfully reproduced.
The LOWA birds were monitored through banding and tracking as soon as they arrived in April.
“Capturing and banding is very important because it allows us to track individuals and survival rates,” Barnes said.
According to Barnes, this is especially useful in LOWAs, as “they return to the same streams year after year and sometimes even to the same territory.”
Barnes also looked at three different types of aquatic insects, ephemeroptera, or mayflies; plecoptera, or stoneflies; and tricoptera, or caddisflies.
These insects are highly sensitive to pollution.
Barnes said, “That’s why I used these insects, along with the LOWA as a bioindicator for the health of the ecosystem.”
In order to sample the insects, Barnes randomly sampled her streams with nets in order to compare macroinvertebrate diversity between benches and ravines.
A problem arose in the sampling of insects at one of her habitats because the sampling method was ineffective.
Despite the difficulties found with aquatic insects, Barnes found that “LOWA metrics suggest that benches are more productive than ravines and are therefore more ecologically important.”
Barnes said that her time at ESU has been “the best two years of my life. It was hard to say I was done, but it’s done.”
Barnes plans to move to Arizona, where she will investigate endangered flycatcher species.
“After that,” she said, “I want to investigate Ph.D. programs and, obviously, job opportunities.”
Email Chris at: