Brookies and Waxy Wool- What does it all mean?

Hello hello, I am Taylor Cox, a research technician for the Grant Lab. Before I delve into the research topic, I want to give away some information about what I do. When I am in the lab, I help prepare samples for analysis, write reports, organize and analyze data, and largely oversee most activities in the lab. I am a recent graduate of Juniata College with a degree in Marine Biology. I been involved with the Grant Lab for a year and a half now and one day, I hope to get a master’s degree in horticulture.

For two and half years I’ve worked on a project addressing the effects of Hemlock Woolly Adelgid (HWA), an invasive insect species (eek!) that feeds on Hemlock trees, resulting in death of the tree. These trees are often near headwater streams, and these hemlock headwater streams have created a tailored ecosystem for brook trout. Hemlock stands create cool temperatures and shaded areas for the associated streams, which allow brook trout to thrive. These ecosystems have been a staple of the Pennsylvania Wilds for eons, but sadly this has been changing in the recent past.


“Waxy Wool”-evidence of hemlock woolly adelgid on hemlock

I know what you’re thinking, and yes, I’m deeply worried as well. But it gets worse. Far, far worse!!!

HWA entered the important hemlock headwater streams about a decade ago. Since their invasion, they have caused the death of many hemlock stands, which may be impacting the associated streams, aquatic ecosystems, and our state fish, the brook trout. This study, which I have been a part of, began two and half years ago in a field biology class, called Field and Stream, taught by Dr. Grant and Dr. Muth (botanist).

During the first year, we studied approximately ten streams. In the riparian corridors of each stream, we collected information regarding the Health of Hemlock (HH) trees by measuring Uncompacted Live Crown Ratio (ULCR) and canopy density (CD). ULCR is a ratio of live branches to the total hemlock tree height, and CD is a measure of how dense the canopy of the tree is. Additionally, both biotic and abiotic terrestrial and aquatic characteristics were collected. We evaluated fish assemblages, diversity, and population estimates with electrofishing, and kick netting was conducted to determine the macro-invertebrates biodiversity. Stream water quality information was collected including conductivity, salinity, total dissolved solids, pH and the water temperature.


Picture of student collecting data

Before I get side tracked, I want to provide some information about the selection of the study sites. We wanted to study hemlock stands that had various degrees of death due to HWA. This would allow us to see if there was a correlation between hemlock decline, due to HWA, and the stream characteristics, such as brook trout populations. After assessing each of the streams, the ULCR and CD values showed us that our study sites fell into three distinct groups, a low (unhealthy), medium (intermediate health) and high (healthy). This information then allowed us to analyze if there was a correlation between the HH and the stream characteristics.

After that first year of data collection, Dr. Grant and Dr. Muth created an introductory biology lab based on the field research class. The students in the introductory lab learn about HWA and potential impacts on streams; especially fish and macro-invertebrate populations.

stream site

Study site used for freshman Bio lab and upper-level Field Biology class

This fall is the third year that data on hemlock headwater ecosystems has been collected by the the two research based classes and summer students. In general, our findings on the impacts of HWA on hemlock headwater ecosystems have just started to develop. With time, we are hopeful we can find out how HWA and a decline in Hemlock Health are affecting aquatic ecosystems. As the data set grows and correlations become clear, we will be able to develop conservation strategies for the wild brook trout and these important ecosystems.

Go Brooks Trouts Go Brook Trouts Go!

Taylor Cox