Area of Expertise: Aquatic food web ecology; trophic interactions between native and invasive species
I am a fish ecologist and joined the faculty in the Department of Fisheries and Wildlife at MSU in July 2008. Teaching is the largest component of my assignment, and I place a heavy emphasis in my courses on understanding fish in the context of the ecosystem, which echoes my research interests. I strive for outreach that engages others to appreciate the challenges of learning about fish in terms of the ecosystem that surrounds them. These parallels across my assignment brings unity to my program, and allows a productive contribution to the Land Grant Philosophy at MSU.
My research seeks to identify factors that influence aquatic food web structure and function across multiple spatial and temporal scales. The overarching theme of this research is to understand how anthropogenic actions (e.g. management and harvest) can affect food web structure and function, and vice versa. This research seeks to understand feedbacks between small-scale processes such as prey choice, movement, stocking, and harvest, and phenomena that occur on larger temporal and spatial scales such as species replacement, recruitment failure, and overfishing. I combine mechanistic and comparative empirical studies with modeling exercises to examine multi-scale hypotheses whose answers may not emerge from either type of study alone.
Much of my research centers around the role of top predators in aquatic ecosystems. Predators represent a nexus of influence on aquatic food webs, and are generally a focus of management. Current research projects are listed below:
Walleye population dynamics in Wisconsin’s Ceded Territory
Together with Post-doctoral researchers Iyob Tsehaye and Matt Catalano (now at Auburn University), I am working with the Wisconsin DNR and Great Lakes Indian Fish and Wildlife Commission (GLIFWC) to develop a model that can assess walleye population responses to varying harvest strategies. This model incorporates long-term data from 25 lakes in the region, and can produce either lake-specific or regional predictions.
Population dynamics of walleye in Michigan’s Inland Waterway
I am working with Dan Hayes (MSU) and the Michigan DNR to quantify recruitment, population abundance, movement, and trophic structure of the four lakes that comprise Michigan’s Inland Waterway (Burt, Mullett, Pickerel, and Crooked Lakes). I currently have a Master’s student that is identifying the abundance and food sources of larval walleyes in the entire system. I am also working with Dr. Hayes’ PhD student (Seth Herbst) on quantifying the food web with stable isotopes. Like all large systems, this body of water offers an interesting combination of complexity (non-native species are currently spreading, walleye may be declining)
Nearshore fish communities in the Great Lakes
I am working with Dana Infante (MSU) and the Michigan DNR to classify nearshore communities of the Great Lakes. The Great Lakes represent a dynamic system, and non-native species have altered both nearshore (<2m deep) and off-shore (>30m deep) communities. However, we have very little idea how invasions (particularly of round goby and Dreissenid mussels) affect areas intermediate to these depths. Although off-shore (>30m deep) and wetland systems of the Great Lakes have been sampled with some consistency through the years, depths between 2m and 30m have not been thoroughly classified. Our goal is to determine species assemblage, trophic structure, and habitat associations of fish that live in these intermediate depths. This project will help develop community health indices based on habitat, and broaden our knowledge of these increasingly important areas.
Siscowet Diel Vertical Migration in Lake Superior
Siscowet are a deepwater form of lake trout (Salvelinus namaycush) native to Lake Superior. Recent research indicates that they undergo daily (diel) vertical migration (DVM) in the water column to feed on native coregonines (chubs) that also undergo DVM. However, it is unclear why siscowet exhibit this behavior given that there are alternative prey (deepwater sculpins) on the bottom, move very litte, and are 10X as abundant as coregonines. I am working with Dr. Thomas Hrabik at the University of Minnesota-Duluth to study this quandary both in terms of the energetic consequences for siscowet (i.e. why they undergo DVM) and the effect of siscowet DVM on populations of coregonines and deepwater sculpins. Our primary research questions are: 1) Why do siscowet undergo DVM? 2) Does coregonine DVM act as a predation buffer (i.e. if coregonines did not undergo DVM, would they suffer heavier predation?), and 3) are siscowet causing deepwater sculpins to decline? We are answering these questions using an individual-based model where siscowet and coregonines explicitly undergo DVM according to our prescription.
I teach three courses, Ichthyology, Field Techniques in Aquatic Ecosystems, and Advanced Fish Ecology. I teach Ichthyology and Field Techniques annually, and Advanced Fish Ecology every other year.
FW 471 Ichthyology (enrollment ~40) 4 credits, Spring semester
This course covers broad topics on fish, providing students with a broad understanding of how fish interact with their environment. Topics include anatomy, form and function, fish senses, physiology, systematics and evolution, ecology, and conservation. This course also has a laboratory section that offers opportunities to dissect fish and provides more in depth instruction on morphology and fish identification.
FW 474 Field Techniques in Aquatic Ecosystems (enrollment ~15) 3 credits, Fall semester
FW 474 is a field techniques course I coteach with Dr. Lois Wolfson. The course is intended to give students hands-on experience sampling aquatic systems for basic limnological parameters (dissolved oxygen, pH, temperature, etc), benthic invertebrates, and fish. I primarily teach course materials related to sampling fish. We travel to several locations throughout mid-Michigan and collect fish using a variety of sampling gears, including electrofishing, fyke nets, seines, and minnow traps. Lectures focus on sampling methodology, including pros and cons of each method.
FW 891 Advanced Fish Ecology (enrollment ~10) (3 credits)
Advanced Fish Ecology is a graduate-level course I teach in fall of alternating years. The course covers a broad range in fish ecology topics, and has a laboratory section where students learn more quantitative methods. Topics covered in lecture include alternative regime theory, stable isotope analysis, modeling fish food webs, and terrestrial-aquatic interactions. The laboratory section is intended to introduce students to the quantitative nature of fish ecology, and students conduct computer exercises in basic stock-recruitment relationships, functional response models, and bioenergetics, among other topics.
Outreach and Service
Outreach and service represent 20% of my assignment. Outreach represents a more substantial part of my research program. The transfer of knowledge from scientists to society is an important responsibility of academia. This idea was not lost on MSU’s forebears, who decided that the University must abide by the land-grant philosophy to remain relevant in society into the foreseeable future. In the Department of Fisheries and Wildlife, knowledge transfer is manifested through collaboration with stakeholders that have an investment in natural resources such as management agencies, public education, and various service activities. Fitting in with this ideal, my research program was purposefully designed to work with public stakeholders towards improving the sustainable utility of natural resources. Students under my guidance work closely with stakeholders to develop research questions that are simultaneously scientifically interesting and whose results will be used by the stakeholder. I work with the following groups to transfer knowledge from my research to the public at large.
Inland Waterway Citizen’s Advisory Council
Great Lakes Indian Fish and Wildlife Commission
Little Traverse Bay Band of Odawa Indians
Chippewa Ottawa Resource Authority
People in the Roth Lab: