As apex predators, dolphins serve as a key sentinel species for monitoring ocean and human health. Data from marine mammal health and environmental risk assessments (HERA) enable resource managers to develop predictive models that evaluate conservation and management strategies. The results of such studies then help to shape legislative policies that govern the irreplaceable natural resources on which all life depends.
The Harbor Branch MMRC HERA Project is a comprehensive, integrated, multi-disciplinary research program designed to assess environmental and anthropogenic stressors, as well as the health and long-term viability of Atlantic bottlenose dolphins (Tursiops truncatus). Health and risk assessments of dolphin populations are especially critical in areas where stocks are depleted or show signs of epidemic disease and/or high mortality, and in areas where the habitat is being intensely altered or impacted by human influences.
The goals of the HERA Project are to develop specific tools and techniques to better identify health threats to dolphins, and to identify links to possible environmental stressors. MMRC HERA protocols were developed as a standardized means to clinically evaluate the overall health of individual animals, as well as identify potential health hazards for entire dolphin populations. In the future, such data may be the very basis that helps shape new environmental preservation policies that legislatively provision more effective conservation management strategies and enforcement capabilities. In doing so, we may help ensure that both humans and dolphins enjoy a higher quality of life.
Additionally, HERA research supports the NOAA Fisheries Service Marine Mammal Health and Stranding Response Program in helping to assess health trends in bottlenose dolphins and correlate data with biological, chemical, physical, and environmental parameters. These data help support management and conservation of bottlenose dolphins by providing biomonitoring and new tools to detect health status and diseases and further aids the investigation of the potential effects of contaminants on immune and health parameters.
Former Harbor Branch Research Professor Greg Bossart and Project Manager Steve McCulloch, initiated the Harbor Branch MMRC Dolphin Health and Risk Assessment (HERA) Project in 2003 under NOAA Fisheries Service Permit No. 998-1678. Initially, the HERA research was formed as a collaborative effort between Harbor Branch Oceanographic Institute and the NOAA National Ocean Service, Center for Coastal Environmental and Bimolecular Research. The research was designed as a multidisciplinary, integrated collaborative effort to assess individual and population health in two southeast estuarine regions, the IRL and Charleston, SC.
During a consecutive three-year period from 2003 - 2005, more than 200 individual dolphins (Tursiops truncatus) were sampled and released in two different, yet similar coastal estuarine regions in the Indian River Lagoon (IRL), Florida and Charleston, S.C. Following this initial comparative research, HERA research activities centered on the Indian River Lagoon (IRL) from 2006 - 2007, where another 40 IRL dolphins were examined, sampled, and released.
Collection and Sampling Methods
Physical examinations are conducted on temporarily restrained dolphins in order to evaluate general condition, and a suite of non-lethal biological samples (i.e., blood, teeth, skin/blubber biopsy, urine, feces, gastric fluid, blowhole cells, etc.) are collected and distributed to over a dozen scientific collaborators for analyses.
Objectives and Expected Significance
The current HERA research plan is organized into (9) individually defined projects. Each project has its own hypotheses, specific objectives and research methods. The projects are organized as follows:
Project 1 - Health Assessment and Surveillance
Project 2 - Emerging Infectious Disease: Lobomycosis
Project 3 - Emerging Infectious/Neoplastic Disease: Orogenital Papillomatosis
Project 4 - Immune Status
Project 5 - Exposure to Mercury
Project 6 - Exposure to Organochlorine Contaminants
Project 7 - Antibiotic Resistance Patterns
Project 8 - Genetic Studies
Project 9 - Photo-identification Studies (General Authorization Letter of Intent)
Longer-term research (and much of what we know about the life history of IRL dolphins) has come from data gathered through examination of stranded animals (Hersh et al. 1990; Barros 1993; Stolen 1998). Stranded animals have provided data for studies on foraging ecology, mortality patterns, age structure, growth, and stock identity. Results from these studies have been critical to the understanding of dolphin habitat use and life history and continue to be valuable sources of information to managers and interested scientists.
Previous studies of health in IRL dolphins were based largely on data from stranded animals. Stranding data for dolphins in the IRL have been collected since the 1970's; higher numbers of seasonal strandings have been reported since 1996 with peak years in 2000 and 2001 (Stolen et al. 2006). During 1993-2000, dolphin strandings in the IRL represented approximately 40% of reported bottlenose dolphin strandings along the east coast of Florida (Stolen pers. comm., 2005). In 2001, an unusual mortality event of unknown etiology occurred in which at least 35 dolphins died over a four-month period in the northern portion of the IRL (Marine Mammal Commission 2001). Pathologic findings in stranded dolphins from the IRL suggested that a substantial portion of the overall observed mortality was due to infectious diseases and that immunologic dysfunction may be a component in disease pathogenesis (Bossart et al. 2003). A variety of skin lesions have been diagnosed in IRL dolphins, including proliferative ulcerative dermatitis due to ciliated protozoans and fungi, dolphin pox dermatopathy, a vesicular dermatopathy of unknown etiology and lobomycosis, a fungal disease of the skin and subcutaneous tissues that occurs only in dolphins and humans (Bossart et al. 2003).