Dr. Susan Cushman is a Research Scientist at the Finger Lakes Institute at Hobart and William Smith Colleges. She is also part of the Faculty in the Biology Department at the Colleges.
What is your role in the Finger Lakes Hg Project?
I am a co-principle investigator on the Finger Lakes Hg project. I work closely with Lisa Cleckner and Roxanne Razavi to coordinate and manage the data collection. As a stream ecologist, I am primarily responsible for collecting all of the stream samples that will be analyzed for total and methylmercury and writing up our results collaboratively. Last summer, my research student Nikki Andrzejczyk, and I visited 3-5 tributaries of 5 Finger Lakes (Owasco, Cayuga, Seneca, Canandaigua and Honeoye) to collect fish, invertebrates, periphyton, and water samples. At each site, we set out to capture 10 fish each of 2 species (Blacknose Dace, Rhinichthys atratulus, and Creek Chub, Semotilus atromaculatus) by electrofishing, and about 15-30 invertebrates from various functional feeding categories (based on how they forage for food): predators, scrapers, collectors and shredders. We also selected a rock that was covered with filamentous algae (periphyton) and filled special water bottles to bring back to the lab for analysis.
How does this project fit into your current research program?
I am interested in a variety of questions related to stream ecosystems encompassing water quality, foodwebs, and species interactions. The Finger Lakes Hg project adds to my focus on biomonitoring, water quality, and understanding the effects of watershed land use on stream community health.
Over the last decade, I have been studying biotic communities in small streams that drain urban, agricultural, and forested watersheds. While water quality measures were historically used to assess stream and watershed health, living organisms like small stream invertebrates called benthic macroinvertebrates, as well as fish have been shown to better illustrate stress in their environment. Indices of biotic integrity (IBIs) are metrics that represent a summary of many variables, and score the health of a system in a single value. Benthic macroinvertebrates (BMI) are commonly used to measure water quality and watershed health because they are relatively easy to collect, requiring only a few pieces of equipment. I have used a variety of IBIs to assess the health of streams in the Owasco, Cayuga, Seneca, and Keuka Lake watersheds.
I also study fish populations and communities in many of these streams. The presence and abundance of some fish are indicators of environmental conditions as tolerance levels vary across species. Blacknose Dace and Creek Chub are species in the minnow fish family, and are not only tolerant of many water pollutants, but also ubiquitous in small streams across the eastern United States. Because of this, they are found in heavily urbanized areas as well as pristine waters alongside trout (but much fewer in number!). Recently, my research team started collecting information about a parasite that commonly infects Blacknose Dace and Creek Chub. A rise in deformities in amphibians has been linked to parasite abundance in pesticide-loaded waters (see work by PTJ Johnson and others). Many subwatersheds in the Finger Lakes are dominated by agricultural landuse and I hypothesize that these parasite infections may be connected to water quality.
What has most interested or surprised you so far?
As a field biologist, I spend much of my time collecting data in the rugged conditions. My days are spent in a pair of waders, and old t-shirt, and lathered in bug spray and sunscreen to protect myself from the elements. Usually when I collect fish samples using my backpack electrofisher, my hands are pretty gross by the end of the day after handling many fish!! The Finger Lakes Hg project brought a new protocol to my repertoire – “clean hands/dirty hands” in the field. While common in many labs, sterile or “clean” hands are not common while doing field work! To properly analyze for Hg, all samples must be collected with minimal personal contact and sterile supplies. One person on the sample collection team has “dirty hands” which means they can touch any of our field equipment without worry. Another person on the team is assigned as the “clean hands” member, which means that they can only touch the sterile sample containers and tools we bring from the lab. This division of labor allows for minimal contamination from other possible sources of mercury into our samples.
To give you more of a visual, we use a LOT of plastic bags. For each site, we take out a bag of sterile bags – in many sizes! We have sample bags, we have bottles in bags, we have gloves in bags and we even have tools like forceps and sieves in bags! All sample processing equipment is sterilized and acid washed before we head out to our streams. And all of our samples are of course double-bagged. The person that has “dirty hands” can only touch the outside bag while the set of “clean hands” can touch the inside sample bag. This may not sound that hard, but you’d be surprised to find that closing a plastic storage bag seal from the outside of another bag or exposing the inside bag to the clean hands member to insert our samples from the outside bag requires some skill! We figured it all out though and found a nice rhythm to our data collection and field processing protocol. Always good to add new tricks to your bag!