Jeff Kovatch - Research

Jeffrey J. Kovatch, Ph.D.

Some current and recent research projects:

Use of stone habitat improvement structures by aquatic biota: The project investigates the use of habitat improvement structures (HIS) built by the US Army Corps of Engineers on the Great Kanawha River in West Virginia and is a collaborative effort with Dr. Dan Evans and Chuck Somerville (MU - BSC), and Dr. Tom Jones (MU -IST). The habitat improvement structures were built Marmet and Winfield pools to provide protection from increased lateral river current associated with traffic from large vessels and commercial barges. The structures are hypothesized to provide current refuges for larval and juvenile fishes and benthic macroinvertebrates. Influences of riparian vegetation, water chemistry, and sedimentation rates, as well as water flow rates, on aquatic biota are being measured as potential predictors of fish abundance and composition. Changes in fish use of the structures over times are being evaluated by considering transient population dynamics using matrix population models. The project began in the winter of 2009 and commences in November 2009. Numerous graduate and undergraduate students are involved in field data collection, sample identification in the laboratory, and data processing.

A view of the structures in the Winfield Pool

Estimation of mass- and temperature-dependent metabolic scaling in native freshwater mussels: Soft tissue mass and temperature explain the majority of variation in metabolic rates and growth across animal taxa. The influences of mass and temperature on the metabolic rates of mussels are being estimated in the lab using Giant Floaters (Pyganodon grandis). This laboratory work is being done in connection with an extensive literature review of mass- and temperature-dependent scaling of metabolic rates across species.

Non-lethal estimation of soft tissue in freshwater mussels. A method to estimate soft tissue mass in mussels without sacrificing them has been developed. Non-lethal soft tissue estimation is a potentially important research tool for studying specimens for which sacrifice is not a feasible option. The approach uses relic shells to generate allometric relationships between easily made morphometric measurements and soft tissue mass. A nice extension of the work is the ability to estimate the ratio of soft tissue mass to internal shell cavity, which has been used by others as an index of mussel condition. Past and current undergraduate students have been involved in aspects of this project. A manuscript outlining the techniques and theory is in preparation and a poster was presented in October 2008 and April of 2009.

Estimation of rates of filter feeding and food preferences in freshwater mussels. Surprisingly little is known about what freshwater mussels can and prefer to eat. Rates of filter feeding with known concentrations of food (e.g., different types of algae, bacteria, DOC) can be used to estimate rates of gross energy intake. Differential rates of filtering with different suspended food items will increase knowledge about mussel diet. The project also addresses the often overlooked behavioral component of relatively sessile filter-feeding animals. Undergraduate researchers are currently involved on this project.

Estimation of rates of heating and cooling of young altricial nestlings in nests and quantification of the maternal contribution to thermoregulation via brooding. Rates of heating and cooling in House Wrens (Troglodytes aedon) were quantified using core body temperature transients from young nestlings (0-7 d) in natural broods in nest boxes in the field. Parental and nestling contributions to thermoregulation during the ontogeny of thermogensis were quantified. Most of the change in regulated nestling body temperature is due to the development of heat generation capabilities and not brooding by the mother (only female wrens brood). This work was done as part of my dissertation and is being prepared for publication. Contact me if interested in the findings.

Modeling rates of heat gain and loss in poikilothermic animals. Patterns of heat transfer from the core in animals are well described second-order negative exponential models. This family of models are used to describe thermal flux in a number of animals including lizards, snakes, small mammals, nestlings, and eggs. For my specific interests in young altricial nestlings, these models were modified to account for (1) the observed conductive-dominated temperature change toward brood-mates before collective convective-dominated temperature change toward the environment. The models were also modified to account for the dynamics that cause a time-lag in directional temperature change after a step-change in the temperature of the environment. Using higher-order negative exponential model to describe thermal flux is relatively more important for larger animals, but the dynamics exist in animals as small as 1 gram. A benefit of thermal transient analysis is the extraction of net metabolic heat production rates for poikilothermic animals. This work was done as part of my dissertation and is published: Kovatch, J.J., Hainsworth, F.R., and Pease, J. 2006. Analysis methods for two types of second-order thermal transients. Journal of Thermal Biology, 31: 247-255. [PDF]

Influence of temperature on growth rates in young House Wrens. Growth rate in altricial nestlings is hypothesized to subject to heavy selection pressures. Altricial nestlings are thought to have decreased allocation of energy to thermoregulation, a form of maintenance, so that resources can be preferentially allocated to growth. However, young House Wren body temperatures are not maintained at adult levels and brooding is energetically not very expensive for parents (see above study). The reason may be that there is no advantage for having warmer nestlings due to a relative invariance of metabolic rates to temperature for young nestlings and an already maximized rate of growth. Nestling body temperatures were experimentally increased in the field for the first half of the nestling period. No change in growth rates were observed. This work was done as part of my dissertation is being prepared for publication.