Doctor of Philosophy (Ph.D.)
Virginia Institute of Marine Science
Robert J Latour
Jan R McDowell
Eric J Hilton
Mark J Brush
andrij Z Horodysky
As fisheries management moves away from single-species approaches and towards more holistic, ecosystem-based approaches, physiological and ecological interactions need to be explicitly considered and mechanistically understood. Accurate portrayals of food web interactions and the direction and magnitude of energy flow between predator and prey populations are fundamental components to further develop ecosystem-based fisheries management (EBFM). to bolster information that is required within an EBFM framework in the Chesapeake Bay, I conducted research designed to advance traditional dietary studies and better understand the form and structure within the Bay's food web. This research relied on controlled feeding experiments, comprehensive sampling of predator and prey communities, and over 10 years of data from the Chesapeake Bay Monitoring and Assessment Program (ChesMMAP) and the Juvenile Fish and Blue Crab surveys. The dissertation presented here has two main objectives: 1) incorporate additional methodologies to improve stomach content identification, and 2) examine the drivers of trophic interactions and consumption within a suite of abundant and economically valuable predatory fishes in the Chesapeake Bay. Prey that is considered unidentifiable is often ignored in stomach content analyses, but can account for a significant proportion of fish diets. in Chapter 1, I demonstrate the use of molecular techniques to detect specific prey consumed by Atlantic croaker (Micropogonias undulatus) and evaluate factors that influence the rate of gastric evacuation. Molecular protocols developed to identify specific prey DNA from stomach contents determined that DNA from blue mussel (Mytilus edulis) can be detected as long as prey resides in the stomach (~30 hours), which is long after prey can be considered visually identifiable. Furthermore, temperature significantly influenced gastric evacuation rates and therefore should be considered throughout the collection process to ensure accurate identification of prey. Chapter 2 evaluated prey selection patterns among three sympatric predators in the Chesapeake Bay: weakfish (Cynoscion regalis), summer flounder (Paralichthys dentatus), and Atlantic croaker. Comprehensive sampling of predator and prey (midwater, zooplankton, benthic) populations revealed selection patterns on dominant prey selection taxa driven by a variety of mechanisms. Bay anchovy selection was significantly influenced by predator size in both weakfish and summer flounder. Mysid selection was driven by both fish size and Julian Day in weakfish and by temperature in summer flounder. Atlantic croaker select for both polychaetes and bivalves, with selection patterns relating to predator size and Julian Day. to evaluate how trophic linkages and environmental conditions influence consumption, bioenergetics models were developed in Chapter 3 for young-of-the-year Atlantic croaker and weakfish. Annual consumption from 2006 – 2016 was estimated and subsequent analyses demonstrated that prey abundance metrics significantly influenced the observed consumption patterns. This research represents a comprehensive study on predator-prey interactions within the Chesapeake Bay and contributes to a broader understanding of fish ecology and production patterns. The results from this dissertation provides a better understanding of food web structure and aids in the development EBFM strategies towards the sustainable use of marine living resources.
© The Author
Sweetman, Christopher James, "Consumption Patterns of Chesapeake Bay Fishes" (2018). Dissertations, Theses, and Masters Projects. Paper 1550153634.
Available for download on Friday, August 09, 2019