Filling in the gaps: a Ph.D. student researches how sediment affects aquatic communities in the NRV and beyond

Heather Govenor
Photo courtesy of Heather Govenor

We have all likely heard some variation of the saying, “too much of a good thing is a bad thing.” We may typically think of this statement in terms of things like sugar or carbs, but it is even true of things deemed to be a necessity. Water is vital for human survival, but too much can poison us. Even oxygen can be toxic in excess.

This thinking also applies to the environment. Sediment is a necessary part of healthy streams, however too much of it can destroy the bug communities that live in them. Researchers rely heavily on bugs and other water creatures to act as an indicator for water quality. When bug communities suffer, humans can ultimately suffer as well.

Right now researchers know that too much sediment is bad for water systems, and that the best practice is to prevent an excess amount of sediment from entering the water in the first place. The next step is to understand exactly what it is about the sediment that is causing the largest problem. Is it the size of the individual sediment particles? Does it have something to do with the way that it settles on the bottom of a stream bed? Heather Govenor, a Ph.D. candidate in the Interfaces of Global Change program, is working to fill in these knowledge gaps in order to best help impaired water systems.

From an outside perspective, it may seem as if the negative impacts of sediment on water systems only affect species and people who directly benefit from that water source. However, Govenor maintains that we are all affected by this issue in some way.

“I think it’s funny that people say ‘I don’t fish’ or ‘I don’t hike’ or ‘I don’t really mind if this stream is dirty’,” said Govenor. “That might be the stream that leads to the river where we pump water that you end up drinking. The more stuff that’s in that water, the more it costs to treat it in a way that makes it safe for you. The bottom line is it affects you and what is going into your body.”

Specifically, Govenor’s work focuses on the effects of fine sediment on aquatic communities. As the name implies, “fine” sediment refers to small particles, ranging from the size of a grain of sand to particles too small to see. Sources of fine sediment include natural soil erosion, agricultural runoff, and drainage from roads. Sediment can enter water systems through natural events such as rainstorms, but sediment input has dramatically increased with human population growth and urbanization. Currently, sediment is the second largest stressor on freshwater streams and rivers nationwide.

Govenor, who began her research in 2014, investigates the impacts that excess sediment can have on aquatic communities based on its placement in the stream. For example, if too much sediment is in the water itself, it can clog the gills of fish. If it is on the bed of the stream, it may not be as harmful to the fish, but it could smother their eggs or the other creatures that live there.

“One of the important facets of understanding sediment involves understanding that it’s never just one thing,” Govenor said.

Govenor is most concerned with species that are aquatic macroinvertebrates. These are water creatures, primarily bugs, that don’t have spines and are big enough that they can be seen without a microscope. Clams, leeches, and mayflies are all examples. Govenor conducted a recently published evaluation, based on conclusions of reports done under the Clean Water Act, indicating that fine sediment is the primary stressor to macroinvertebrates in the U.S.

Govenor chose macroinvertebrates in part because of her strong background in entomology, but also because monitoring the presence and population of macroinvertebrates is helpful in determining the health of a stream.

“Insects are the most commonly used [species] for water quality assessment around the world, not just in this country, so it was just this perfect blending of my past work with insects [and] my current work with contaminated environments and trying to clean them up. I just had a very strong curiosity about how everything works together,” Govenor said. 

She primarily works with biological monitoring data, which is obtained by collecting macroinvertebrates in a water system, classifying, and counting them. These data are compared to what would be considered normal for the area. The differences reveal whether or not there is a problem.

Govenor is also conducting an experiment that allows her to track the journey of sediment from its entrance into a water system to its exit. The experiment will help her determine how sediment naturally moves in a water system and also how long it takes to be flushed out of the stream, which has important implications for how long it may take to clean excess sediment from impaired stream systems.

Although Govenor’s dissertation work focuses on sediment, her past experiences in treating contaminated streams and rivers have taught her the importance of looking at the whole picture when it comes to the health of a water system.

“I do a lot of work with contaminated sites, and we may look at sediment samples and determine the problem is that there’s too much mercury in that sediment, but in that case we’re just focusing on the toxic effect and not recognizing that there might be an additional stress to those animals just from the presence of too much fine sediment in their system,” Govenor said. “It’s really about understanding the system and not just solving pieces.” 

Much like Govenor’s research never focuses on one thing, her daily life is multifaceted as well. Along with her dissertation research, Govenor fills her days with her work as an ecological risk assessor, a TA for a geographic information systems course at Virginia Tech, and most importantly, as a mother.

In all of the roles she fulfills, Govenor has one primary objective.

“Both the work I do as a consultant and what I’m working on now for my degree very much focuses around creating, maintaining, and appreciating our need for a clean environment,” Govenor said. “My focus is protecting human health and the environment in a nutshell in whatever way I [can] do that.”

Govenor, H, LH Krometis, and WC Hession. (2017) Invertebrate-Based Water Quality Impairments and Associated Stressors Identified through the US Clean Water Act. Environmental Management. 
DOI : 10.1007/s00267-017-0907-3

 

Q&A:

Program:

Biological Systems Engineering

Dissertation Advisors:

Drs. Leigh-Anne Krometis and Cully Hession

Other Academic Degrees:

B.S. in Biology (Mathematic Minor), Pennsylvania State University

M.S. in Entomology, Michigan State University

When did your interest in science and the environment begin?

My dad would always take us on trips like caving or climbing or hiking so I spent a lot of my weekends doing that. He really instilled this appreciation for nature and kind of leaving things better then they were when you got there. It was like a genetic part of me.

What do you do when you are not researching?

I look at houses online. I’m actually thinking of getting little houses and fixing them up and renting them out and doing that kind of thing. My procrastination is HGTV, sewing, time with friends, and wine.

 

Article written by Lisha Long