Sea Grant Program: Mississippi Alabama Sea Grant Consortium
Title: Use of stable isotope ratios to link wastewater sources to effects on shellfish and human health
Start Date: 02/01/08
Duration: 2 years
Project Leader: Carmichael, Ruth H.
Affiliation: Dauphin Island Sea Lab
Sea Grant Funds (2 years): $99,995 (State Appropriations)
Matching Funds: $0
Keywords: Oyster, stable isotope, nitrogen, fecal coliform, MSB, virus, shellfish, wastewater
Objectives:
- Our primary objective is to collect data that will enhance coastal economies by helping to maintain and restore local shellfish populations, increase the area of land available for shellfishing, inform efficient determinations of market-safe shellfish, and reduce the risk of harvesting contaminated shellfish.
- Specifically, we propose to meet these objectives by:
- 1) clearly defining links between wastewater sources and effects on fisheries and human health and
- 2) determining the spatial and temporal scales of WTP-related effects for management.
Methodology:
We propose to team with the U.S. FDA on Dauphin Island to determine whether WTP discharge affects growth and survival of shellfish or their safety for human consumption. We will take a novel approach to this problem by combining 1) FDA measurements of a highly reliable enteric pathogen proxy (MSB) and the traditional fecal coliform test with 2) measurements of a natural tracer of anthropogenic wastewater sources (N stable isotopes), 3) measurements of potential wastewater-driven changes on shellfish habitat (DO) and food supply (nutrient and chl a concentrations), and 4) measurements of variation in shellfish growth and survival through time. To determine spatial and temporal extent of wastewater influences, we will measure stable isotope ratios in tissues of sentinel bivalves (C. virginica) and particles in estuarine water at locations, varying in proximity from the WTP on McDuffie Island in Mobile Bay (parallel to existing FDA sampling sites).
Based on the results of year one, in year two we will choose sampling locations to best capture variation in dilution due to hydrology and level of WTP processing. To do this we will either repeat our sampling at modified locations relative to the McDuffie WTP or shift our scheme to the lower flow, but higher treatment level WTP on Dauphin Island.
Rationale:
Wastewater treatment plants (WTP) account for more than 30% of shellfish area closures in the U.S. and >70,000 ac in Mobile Bay. Shellfishing areas near WTPs are typically closed to fishing due to fecal coliform concentrations that may indicate human health risk. The reliability of this indicator, however, is uncertain. The FDA on Dauphin Island is testing an alternative indicator, male-specific bacteriophage (MSB), but lacks a method to definitely link their findings to wastewater sources. We offer a stable isotope approach that will 1) identify wastewater sources parallel with microbial indicators and 2) help determine the spatial extent and time courses of these effects. This study addresses concerns within several MASGC priority areas, including: 1) testing a predictor that links land-use planning to water quality and ecosystem health, 2) assessing the responses of living resources to pollution and, 3) testing and refining a method for more affective detection of biological contaminants in commercial shellfish.
For More Information Contact: the MASGC Research Coordinator, Loretta Leist (Loretta.leist@usm.edu).
Please reference the project number R/CEH-28.
