The goal of this consortium is to further understand how the toxic effects of oil from the Deepwater Horizon (DWH) disaster impacted cetaceans in the northern Gulf of Mexico. While previous studies have shown that DWH oil exposure led to a variety of adverse physiological effects in dolphins and other marine species-- including increased rates of reproductive failure, lung and cardiac disease, poor body condition, and increased rates of infections-- many questions remain unanswered.
Through a combination of thematic projects, field assessments, and integrative modeling, CARMMHA will provide a comprehensive understanding and synthesis of the health impacts of oil-associated chemicals on cetaceans, and a suite of models that will integrate available information collected prior to the spill, immediately following the spill, and over 8 years after the spill, to demonstrate where population-level impacts have occurred and to reassess the current recovery trajectories for Gulf of Mexico cetaceans. Our primary objectives are to:
- Conduct innovative veterinary and/or laboratory studies to address priority scientific questions related to health effects of oil exposure in dolphins that have emerged from prior studies;
- Integrate data from lower taxa to understand the potential indirect effects on dolphins from ecosystem changes that occurred before, during, and after the DWH spill in Gulf of Mexico bays, sounds, and estuaries;
- Fill a critical information gap related to the current health status of dolphins outside of the previously studied bays, sounds, and estuaries following the DWH oil spill;
- Apply state-of-the-art modeling approaches to synthesize all available data and information from prior and on-going studies, as well as new information from the above objectives, to develop new population recovery trajectories for multiple cetacean stocks.
Our consortium is particularly interested in the following topics:
- Cardiotoxicity: Studies of fish species (GoMRI RECOVER consortium and DWH Natural Resource Damage Assessment [NRDA] studies) have established oil-related cardiotoxic endpoints, and our ongoing GoMRI V study (PI Smith) has suggested cardiac abnormalities in dolphins from heavily-oiled Barataria Bay. We will develop and validate innovative diagnostic techniques using the well-studied population of dolphins cared for by the US Navy, which can then be applied in field assessments to characterize the current cardiac health of Gulf of Mexico dolphin stocks.
- Immunotoxicity: During the DWH NRDA and the GoMRI V study, researchers documented immune system aberrations in Barataria Bay dolphins, but the evaluation was limited by the techniques available at the time. We will use the dolphins cared for by the US Navy to develop and validate innovative diagnostic techniques, which can then be applied in field assessments to characterize the current immune status of Gulf of Mexico dolphin stocks.
- Dietary and trophic assessments: A prior GoMRI II study (PI De Guise) and other recently published studies suggest effects (both adverse and beneficial) in lower trophic species of inshore Gulf of Mexico ecosystems following the DWH disaster. Such changes would have indirect effects on the nutritional state of dolphins, which are apex predators in these ecosystems. We will study dietary & trophic assessments using stable isotope and fatty acid signatures of existing archives of dolphin and fish tissue samples from before, during, and after the spill, as well as samples from new field assessments, to help define the diets, foraging habitat use, and food web linkages for dolphins.
- Comparative dolphin health assessments: In addition to conducting further field assessments of previously studied northern Gulf of Mexico dolphin stocks (e.g., Barataria Bay and Sarasota), we will fill a critical information gap by evaluating the health of dolphins from the Northern Coastal Stock (i.e., dolphins inhabiting waters from the shore outer bay boundaries to the 20-m isobaths). CARMMHA will address the uncertainty associated with extrapolating results from bay, sound, and estuary dolphin stocks to coastal dolphin stocks, which were also highly exposed to DWH oil.
- Integrative modeling: CARMMHA will develop improved and up-to-date predictions of population recovery trajectories with robust measures of uncertainty for key cetacean stocks. We will 1) integrate information relevant to health, demography, abundance, and environmental stochasticity from prior studies, including GoMRI and NRDA efforts, with new information from the CARMMHA field and thematic projects, 2) conduct a formal expert elicitation to estimate recovery timelines for survival and reproductive rates, and 3) synthesize new data and information on abundance trends that are emerging from the Gulf of Mexico Marine Assessment Program for Protected Species (GoMMAPPS) to inform model predictions.
Finally, CARMMHA is committed to GoMRI’s mission to improve society’s ability to understand, respond, and mitigate impacts of petroleum pollution and related stressors on the marine and coastal ecosystems. Our research objectives will be informative to ongoing restoration efforts, resource management, and mitigation efforts aimed at reducing the effects of stressors on cetacean populations and improving the long-term environmental health of the Gulf of Mexico. We will disseminate our results by targeting outreach to the restoration community, broader scientific community, general public, and Gulf of Mexico community youth groups, including a proposed Gordon Research Conference on comparative toxicity and adverse health effects of oil-associated chemicals on multiple taxa and a collaborative effort with the Girl Scouts designed to garner the potential for CARMMHA’s women scientists to inspire young girls to pursue careers in science.