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

Lead Investigator: Ryan Takeshita, National Marine Mammal Foundation, ryan.takeshita@nmmf.org

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 (frank.parker@noaa.gov)

Award Amount: $65,113

Award Period: September 2021 – August 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 hurricanes) and anthropogenic (e.g., vessel traffic and construction noise) events. These stressors have adverse effects on the health of the dolphins and negatively impact survival. There is a need to better understand the impacts of each individual stressor in the Houston area and their combined effect on dolphins at both the individual and population level. Reducing these uncertainties would improve the decision making process regarding the assessment and restoration of marine mammals in the face of multiple stressors. This is particularly useful for natural resource damage assessments (NRDAs) which determine the extent of environmental damage following events like oil spills and outline restoration actions.

What the team did: The project team held a four-day workshop with an interdisciplinary group of scientists and natural resource managers. Together, they generated a series of potential directions for future research, including a list of combinations of stressors that could drive negative impacts. They identified currently available data that could shed light on potential interactive effects among stressors and identified gaps in our knowledge of these interactions that still need to be filled.

Summary of outcome: Based on input from the workshop, the team wrote a research and application plan which includes study designs to fill the identified data gaps. The team synthesized the information from the workshop into a conceptual model for dolphins and their stressors in the greater Houston area, with a specific eye towards NRDAs (including response, injury assessment, and restoration planning/monitoring). The project team was awarded funding from the Science Program in 2023 to implement their plans.