Current Work
Mussel-Flow Interactions
The hydrodynamic forces created by flowing water are critically influential to the behavior, distribution, and ecology of benthic organisms in stream ecosystems. These forces help regulate a number of ecological and physical processes, such as filtering efficiency of benthic filter feeders, nutrient mixing, sediment transport, and near-bed flow patterns, to name a few. My research is currently examining how freshwater mussels interact with and influence near-bed turbulent flow characteristics. This work is currently being supervised by Professors Joe Atkinson and Sean Bennett.
Environmental DNA
Organisms shed DNA into their environments. I am interested in the rate at which freshwater mussels shed DNA into their environment, and how this DNA persists in both space and time within stream ecosystems. The goal of this research is to better understand how we might use molecular technologies such as quantitative polymerase chain reaction (qPCR) to monitor species of interest and freshwater ecosystems. This research is currently being supervised by Professor Lauren Sassoubre.
Swimming capacity of Emerald Shiners
The emerald shiner (Notropis atherinoides) is an important forage fish in the Great Lakes. Due to extensive shoreline modification, hydrodynamic barriers in the Niagara River prevent this shiner from completing its migration upstream into Lake Erie. I have assisted Kendra Vorenkamp, a fellow Ph.D. student, in investigating the critical swimming speed of the emerald shiner. The goal of this project is to determine the swimming capacity in order to inform a new design of the shoreline where the greatest hydrodynamic barrier is located. This research is an on-going effort supervised by the U.S. Army Corps of Engineers, SUNY UB, and Buffalo St. College. More highlights of this research can be found under the News tab.
Past Work
Age and Growth Dynamics of Mussels
Similar to how trees deposit growth rings, mussels also deposit conspicuous growth rings on the internal and external surface of their shell. Mussel shells can be cut to create thin sections from which the internal growth rings can be clearly observed. Both internal and external growth rings can be used to age mussels, determine growth rates, and examine how mussels respond to various climatic parameters. I have applied common dendrochronological applications to analyze the rate of ring deposition within freshwater mussels, and have compared the application of internal and external ring processing methods. Using the dendrochronology techniques, false or missing rings can be identified, which is essential for accurate aging. Furthermore, these techniques allow for the rate of ring deposition to be verified by comparing the growth increments to climatic variables or previously dated populations.
In these studies, I have found that internal growth rings are more accurate to obtain ages, but there is usually a consistent difference between internal and external ring counts. External aging typically underestimate the age, as early growth rings are eroded on the umbo of the shell or the most recent growth rings are hard to differentiate near the shell margin. In species where external rings are conspicuous, growth rates are similar between internal and external processing methods. This becomes important when working with threatened species, as important growth information can be obtained without destructively sampling mussels.
In these studies, I have found that internal growth rings are more accurate to obtain ages, but there is usually a consistent difference between internal and external ring counts. External aging typically underestimate the age, as early growth rings are eroded on the umbo of the shell or the most recent growth rings are hard to differentiate near the shell margin. In species where external rings are conspicuous, growth rates are similar between internal and external processing methods. This becomes important when working with threatened species, as important growth information can be obtained without destructively sampling mussels.
Bottom-Up Transfer of Mussel-Derived Nutrients
As filter feeders, mussels transform nutrients into readily available forms, which can serve as a local nutrient subsidy. The nutrients transformed by mussels stimulate primary production, which in return benefits secondary production. The extent of this bottom-up transfer of mussel-derived nutrients is not known in freshwater water ecosystems. For my master's thesis, I investigated if mussel-derived nutrients are influential at higher trophic levels, specifically among fish, and examined a potential mechanism that contributes to the nutrient subsidy.
Through a series of mesocosm experiments and a observation field study, I found that mussels have a positive influence on fish communities. Fish health was greater when raised among a dense mussel population, and a higher abundance of centrarchid fish species was observed over mussel sites relative to non-mussel sites in a southeastern Oklahoma river. To look at the mechanism contributing to the nutrient subsidy, I used a stable isotope (n15) to trace mussel-derived nitrogen through the food web. Here, I found that mussel-derived nitrogen was assimilated among both primary (benthic algae) and secondary (macroinvertebrates) production, which suggests that the ability of mussels to transform nitrogen into a readily available form is a contributing factor to the positive influence on primary and secondary production. |