Dynamic Stability and Particle Transformations: Tracing Pathways of Production in Estuarine Turbidity Maxima

点击翻译按钮获取中文摘要

This project entails interdisciplinary research on the complex processes controlling structure, dynamics, and productivity of Estuarine Turbidity Maxima (ETMs). Led by Dr. Ed Houde, it builds on extensive results of the Bio-physical Interactions in the Turbidity Maximum (BITMAX) program in the Chesapeake Bay. ETMs are physical features located at the heads of coastal plain estuaries near the freshwater/saltwater interface. They trap sediment, detritus, zooplankton and fish early-life stages, enhance secondary production, and exercise control over recruitments of anadromous fish. The BITMAX project substantially advanced fundamental knowledge of ETM structure and dynamics, but also identified critical gaps in understanding processes and mechanisms that are addressed in this proposal. The new research objectives are to define and evaluate processes and mechanisms promoting secondary production in ETMs. In BITMAX, the ETM was identified as a region of dynamic stability where restoring forces, both physical and biological, modulate the ETM ecosystem and periodically enhance trophic transfer. It is proposed that mechanisms promoting dynamic stability in ETMs are strongly associated with particle transformations and water column stratification that lead to predictable particle delivery, entrapment, nutritional enrichment, and trophic transfer from microbes to zooplankton to fish. The research will address four hypotheses: 1) particle aggregation promotes formation and retention of nutritious particles in the ETM, 2) particle attached bacteria enrich the nutritional value of food for copepods, transforming the microbial loop into a microbial shunt, 3) abundant food and stable stratification enhance the feeding conditions and production of copepods and fish larvae, and 4) life-history strategies of key ETM species are adapted to take advantage of event-scale changes (pulses) in ETM circulation patterns. The integrated research program will be conducted through comprehensive and coordinated field, laboratory, and numerical modeling experiments in the ETM region of upper Chesapeake Bay. The proposed research will expand knowledge of estuarine processes in physical and biological disciplines. Results will advance knowledge of estuarine physical oceanography and sediment transport by improving understanding of stratified tidal turbulence, particle aggregation dynamics in eutrophic environments, and ETM particle trapping. ETMs are highly productive regions in coastal-plain estuaries throughout the world. They serve as critical nursery areas for economically important fishes. Competing human interests impact physical and/or biological characteristics of the ETM via freshwater diversion, dam construction, excessive nutrient loading, channel dredging, and fisheries harvests. This project has strong education and outreach components. Graduate and undergraduate students will be trained in field, lab and modeling techniques in a multidisciplinary research program. A teacher Fellow will gain experience working with scientists and translating research results into lesson plans. In addition to directly fostering scientific careers of students, research results will be disseminated through frequent interactions with resource managers in the Chesapeake Bay Program to ensure that societal benefits are communicated effectively.