Toxic effects of the oil resulted in some dolphin and whale stocks losing over half of their population, and without any active restoration, these stocks may take over 50 years to recover (DWH NRDA Trustees, 2016).
However, questions linger about the biological mechanisms by which the oil caused illness, death, and reproductive failure, as well as how long the effects may last into the future.
To address these questions, our team of marine mammal scientists is excited to announce the start of the Consortium for Advanced Research on Marine Mammal Health Assessment! CARMMHA is a research consortium funded by the Gulf of Mexico Research Initiative (GoMRI).
Over the next two years, CARMMHA’s goal is to produce a suite of updated models that will combine data from before, during, and the eight years after the spill to look for any potential population-level impacts and update the recovery trajectories for the injured stocks of dolphins and whales.
We are an interdisciplinary group of researchers with extensive experience in cetacean biology and physiology, environmental toxicity, trophic ecology, statistical analysis and modeling, and marine mammal medicine from 12 institutions with a unique combination of expertise, passion, and curiosity for studying the toxic effects of oil on Gulf of Mexico cetaceans. Drs. Lori Schwacke (Lead Principal Investigator and Consortium Director) and Cynthia Smith (Deputy Director) from the National Marine Mammal Foundation will lead the research efforts and plan to especially focus on how to synthesize the various streams of data into a comprehensive understanding of oil’s adverse health impacts. Building on their experience with the DWH NRDA, Drs. Schwacke and Smith will oversee CARMMHA’s combination of thematic projects, field assessments, and integrative modeling. Our consortium has four main objectives:
Cardiotoxicity and Immunotoxicity
Develop and use innovative veterinary and laboratory techniques to study how oil affects cardiac and immune health in wild dolphins exposed to DWH oil.
Studies of fish species (e.g., GoMRI RECOVER consortium; Bayha et al., 2017; and DWH NRDA Trustees, 2016) have established oil-related cardiotoxic and immunotoxic endpoints, and our ongoing GoMRI V study (PI Smith) has suggested cardiac and immune abnormalities in dolphins from heavily-oiled Barataria Bay. We will develop and validate innovative diagnostic techniques, which can then be applied in field assessments to characterize the current cardiac health of Gulf of Mexico dolphin stocks. We will use archived samples from previous Gulf of Mexico field efforts and the well-studied population of dolphins cared for by the US Navy to work on our methodology before our CARMMHA field work.
Food Web Changes and Dolphin Diets
Investigate how DWH’s effects on fish and crustaceans may have affected Gulf of Mexico food webs and therefore dolphins’ diets and health.
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
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.
CARMMHA will conduct field health assessments of dolphins in Barataria Bay, Sarasota Bay (an unoiled reference stock), and in the waters outside of Mobile Bay, AL. Our team has conducted health assessments on the stocks in Barataria Bay and Sarasota Bay several times since the DWH oil spill, and these data will provide additional information on the long-term effects of oil exposure. During our Alabama fieldwork, we will fill a critical information gap by evaluating the health of dolphins from the Northern Coastal Stock. 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.
Apply state-of-the-art modeling approaches to synthesize all available data and information to develop new population recovery trajectories for various northern Gulf of Mexico dolphin and whale stocks.
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.