Dr. Pieter deHart
I examine the biological connections between organisms and their food, and what role that plays in the environment as a whole. Through sampling the tissues of predators ranging from fish in the Amazon to coyotes in New England (and everything in between), I work closely with students to reconstruct past and present food webs to determine how organisms adapt to and interact in rapidly changing habitats around the globe.
The common thread that weaves together my research is a focus on dietary physiology and its application to conservation biology. Undergraduate students are involved throughout the research process as we pair the analyses of stable isotopes of organismal tissues with population surveys to answer questions related to foraging ecology, migratory patterns, and behavior. A marine biologist by training, I regularly collaborate with complementary experts to examine how environmental change drives multiple biological responses in marine and aquatic communities. My current projects include:
Examining the impacts of the small Indian mongoose invasion on sea turtle populations in the Caribbean.
As one of the most pervasive invasive species on tropical and subtropical islands, mongoose (Herpestes auropunctatus) have initiated huge shifts in community ecology both on land, and at the land-sea interface. In particular, they seem to be predating upon the eggs of endangered sea turtles. This work is a collaborative effort with students and researchers from Radford University and the parks service on St.John, USVI, and aims to reconstruct the complete diet of the small indian mongoose throughout the Caribbean. The initial results of this work will be coming out in BIOS in December 2016, and we are expanding current sample collection to include the equally invasive and destructive Black rat, to measure the degree to which they may be exhibiting co-predation or competitive exclusion on the islands.
Terrestrial carnivory drives complex trophic interactions and population patterns throughout eastern North America.
For more than six years, I have been working with students to examine patterns of local terrestrial carnivory (e.g., coyote, red fox, gray fox), and exploring the many questions that remain regarding what specifically drives the populations of these mammals both temporally and spatially. By applying genetic and stable isotopic analysis to monitored canine species, we have been able to conduct a forensic examination of the trophic impacts these species exert on the local and regional ecosystems. We are exploring how coyote (Canis latrans) predation impacts local wild turkey (Meleagris gallopavo) populations in regions ranging from Georgia to Virginia, and plan to extend this work in a comparative study in northern New England.
Food web reconstruction of the Brazilian Amazon. What are the unexpected consequences of deforestation on fundamental fish species?
For the past two years, I have been pursuing multiple research projects with researchers at the Federal University of Amazonas (UFAM) in Brazil to explore the trophic ecology of native and endangered fish species in the acidic Rio Negro (blackwater river). Given that this region is at the forefront of dealing with some of the most pressing problems related to both global climate change and anthropogenic interactions, this work is critical to understanding global ecosystem processes. My most recent projects have involved bringing students to Brazil with me to explore autotrophic energy sources of freshwater stingrays (Potamotrygon spp.) through carbon isotopes, compare the diet of Tucunaré-açu (Cichla temensis, aka, Peacock bass) between acidic and alkaline river habitats, and examine the role of herbivory in the food web of red piranha (Pygocentrus natteri) throughout the Amazon. Additionally, we are finalizing submission of work on fish food webs in aquatic macrophyte stands of Amazonian floodplain lakes for publication in early 2017.
Population biology of marine mammals in Gulf of Maine and Bay of Fundy.
Since 2007, I have been guiding students in a field course focused on marine mammals and seabirds in the Bay of Fundy. Throughout this time, we have been consistently collecting population and physiological data on the megafauna found in this productive region. We are most interested on how bathymetric features dictate the distribution and abundance of baleen whales, and are exploring the interspecies foraging interactions of the most commonly found species (e.g., finback, minke, and humpback whales) throughout the region.