Developing New Tools To Document Waste Nutrient Flow in Tropical and Subtropical Marine Fish/Bivalve Integrated Culture Systems

EPA Grant Number: U916238
Title: Developing New Tools To Document Waste Nutrient Flow in Tropical and Subtropical Marine Fish/Bivalve Integrated Culture Systems
Investigators: Watts, Jennifer L.
Institution: University of California - Davis
EPA Project Officer: Lee, Sonja
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $92,653
RFA: STAR Graduate Fellowships (2003) Recipients Lists
Research Category: Aquatic Ecosystems , Fellowship - Oceanography and Coastal Processes , Academic Fellowships


The objectives of this research project are to: (1) examine and compare the pathways of nutrient flow (with an emphasis on nitrogen) through experimental fish/bivalve integrated culture systems in two distinct study sites, an arid subtropical coastal lagoon near La Paz, Baja California Sur, and the tropical Gulf of Nicoya in Costa Rica; and (2) test the hypothesis that geochemical analysis of bivalve shell material that combines delta18O, delta13C together with delta15N values obtained from nitrogen in the shell organic matrix can produce a temporal record of shell delta15N from which inferences can be made about variation in delta18N from the particulate organic matter bivalve food resources found in coastal ecosystems.


This research project involves characterizing relevant aspects of physical (e.g., currents) and biological processes near fish cages and at control sites using a multifaceted approach that combines simulation modeling with empirical data collection, plus some new applications of stable isotope geochemistry, that can provide insight into the fate of nutrient wastes released from fish cages. The data set collected at the two study sites will be used to test the hypothesis that nutrient inputs originating from fish cages are identifiable and can alter ecological processes, such as nutrient uptake relationships, in coastal environments. This research project blends investigation into practical questions relevant to the management of coastal fish farm development with the generation of new tools for the study of aquatic ecosystems that together can shed light on the behavior of nutrient wastes in coastal environments. With the limited capacity for capture fisheries to meet future demand for seafood, fish farming in the coastal zones, especially in low-latitude developing countries, will become a priority. This research project will point the way to the implementation of environmentally sensitive net-pen culture of marine fish in tropical and subtropical regions of the world. The proposed new geochemical techniques to intensively study a known source of nutrients also have great potential applicability to other locations and situations, and as such, will provide knowledge that can enhance management of coastal zones worldwide.

Supplemental Keywords:

fellowship, waste nutrient flow, marine fish/bivalve integrated culture systems, marine fish, subtropical, tropical, nutrients, nutrient wastes, California, CA, Costa Rica, nutrient flow pathways., RFA, Scientific Discipline, Geographic Area, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Nutrients, Aquatic Ecosystems & Estuarine Research, State, Aquatic Ecosystem, Aquatic Ecosystems, Biochemistry, Ecology and Ecosystems, International, coastal ecosystem, dissolved organic matter, nutrient dynamics, ecosystem monitoring, estuaries, nutrient concentrations, nutrient flux, coastal environments, photochemistry, Costa Rica, La Paz, nutrient cycling, California (CA), ecosystem stress, subtropical marine fish, nitrogen

Progress and Final Reports:

  • 2003
  • 2004
  • Final