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Multiple Stressors on Dolphins

Full Title: Developing a research framework to support assessments of cumulative effects from multiple stressors on dolphins in the Houston area under CERCLA and OPA

This project will establish a collaborative working group to scope and design an evaluation framework for the assessment and restoration of Gulf of Mexico marine mammals in the face of multiple stressors.

Bottlenose dolphins in the Gulf of Mexico
Photo by Mike Hendon, NOAA Teacher at Sea Program

Lead Investigator: Ryan Takeshita, National Marine Mammal Foundation,

Natural Resource Manager: Michel Gielazyn, National Oceanic and Atmospheric Administration

Project Team: Teresa Rowles (National Oceanic and Atmospheric Administration) and Lori Schwacke (National Marine Mammal Foundation) 

Federal Program Officer/Point of Contact: Frank Parker (

Award Amount: $65,113

Award Period: This project began in September 2021 and will end June 2023.

Why it matters: Common bottlenose dolphins living in coastal waters near Houston, Texas are exposed to multiple chemical contaminants, as well as stress from other natural (e.g., freshwater inundation from Hurricane Harvey) and anthropogenic (e.g., vessel traffic and construction noise) events. Reducing the uncertainty about the cumulative effects from multiple stressors will improve the decision-making process concerning dolphins. The ultimate goal is to build a framework that will allow decision makers to evaluate the relative impacts of 1) each individual stressor in the Houston area and 2) their combined effect on dolphins at both the individual and population level. To achieve this, the project team will establish a multi-disciplinary working group of technical subject matter experts, regional stakeholders, and resource managers. The working group will design a project plan using existing data from the Houston area and serve as an ongoing source for marine mammal resource management in future decision making throughout the Gulf of Mexico and U.S. waters. 

What the team is doing: The working group will hold a four-day workshop to scope and design the project based on the recommendations from a National Academy of Sciences, Engineering, and Mathematics panel. The project team will then coordinate with the working group to co-produce a Research and Development plan and Application plan based on the workshop outcomes, which will be shared with resource  managers who make decisions about Houston-area dolphins and other Gulf marine mammals.

Expected outcome: A working group of NOAA resource managers; technical subject matter experts in toxicology, epidemiology, modeling, and veterinary science; and regional dolphin experts will develop a Research and Development Plan and Application Plan for Natural Resource Damage Assessments (NRDAs) and other related assessments with multiple stressors. The plans will describe and quantify the multiple stressors facing dolphins in the Houston area so that they can be considered for NRDAs.

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