Brugia Malayi - Clark Science Center - Smith College

Marine Mammal Health and Toxicology
Victoria Dunch
Coastal waters in the United States have become highly contaminated with pollutants as a result of industry, development and
general non-point source pollution. The effects of these pollutants, which may bioaccumulate in the environment, are not well
understood, but are believed to have a serious effect on marine mammal health. High concentrations of various pollutants such
as Polychlorinated biphenyls (PCBs), Polybrominated diphenyl ethers (PBDEs), Perfluorocarbons (PFCs) and pesticides such as
DDT have been found in blubber samples of Atlantic bottlenose dolphins (Tursiops truncatus). 1 PBDEs, for example, are used as
flame retardants on a wide variety of products including building materials, electronics, furnishings, plastics and textiles. At high
concentrations it is believed that these pollutants can compromise an animal’s immune system, which could contribute to mortality
events either directly or indirectly from a compromised immune system allowing pathogens to invade. Bottlenose dolphins are apex
predators, and thus accumulate high levels of pollutants from the environment. By studying the effects of toxins on these animals
we may also grasp an understanding of their effects on us.
Several projects have been undertaken to study the effects of chemical contaminants on these animals. One is the Bottlenose
Dolphin Health and Risk Assessment (HERA) Project, which aims to assess the health of two populations of bottlenose dolphins
in two estuarine areas on the United States’ eastern coast, Charleston, South Carolina (CHS) and the Indian River Lagoon, Florida
(IRL). Over the course of two weeks beginning in June 2012, we received eleven skin samples obtained from dolphins captured
and released in the IRL site. These samples were then incubated at 37° C and 5% CO₂ for twelve days in the hopes of growing
fibroblast cells which we would then freeze down for cell storage and future testing. After about six days, the flasks of skin samples
had to be observed daily for changes and fibroblast growth. Although unfortunately our samples became contaminated, most likely
by a fungus, I learned sterile laboratory techniques and gained skills in cell culture methods.
A tremendous amount of preparation is needed in order to conduct a dolphin health assessment study. I contributed to
preparing the sample preparation kits for the collection of gastric, fecal, blowhole, urine, and blubber samples which will be used
for the dolphin health assessment study in Charleston next summer. I was responsible for sterilizing necessary equipment, labeling
and constructing the field kits and creating and inventory of all the various sample supplies such as veterinarian animal supplies,
tubes, needles, syringes, and vials.
A master’s thesis immune study to evaluate the effects of DE-71, a mixture of flame retardant chemicals, on macrophages
was also in process. Spleens from B6C3F1 mice were minced and 1 million yeast cells were added to the macrophages to mimic an
invasive body for them to engulf. DE-71 was then introduced at environmentally relevant concentrations from 0.0, to 0.05, 0.25,
0.5, 2.5, 5.0, 25.0, and 50.0 µg/mL to determine if rates of phagocytosis differed. 2 This process was repeated on 30 slides which
were then counted to determine the average engulfment rate for each concentration. I was involved in counting these slides on a
Zeiss Axiovert S100 microscope to determine the percentage of phagocytosis.
I was able to count roughly 30% of the slides this summer and the trends suggest that DE-71 may have a negative effect
on macrophage phagocytosis. With the plethora of contaminants now found in marine environments, and with new chemicals
being released every day, it is of increasing importance to better understand the effects of such pollutants on human and marine
mammal health. (Supported by the Agnes Shedd Andreae 1932 Research Internship Fund)
Advisors: Joanne Benkley and Patricia Fair, Center for Coastal Environmental Health &
Bimolecular Research, National Oceanic and Atmospheric Administration (NOAA)
References:
1
Fair, Patricia A. et al. 2010. Contaminant blubber burdens in Atlantic bottlenose dolphins (Tursiops truncatus) from two southeastern U.S.
estuarine areas: Concentrations and patterns of PCB’s, Pesticides, PBDE’s, PFC’s and PAH’s. Science of the Total Environment, 408. 1577-1597.
2
Wirth, Jena R. Emerging Contaminants in the Marine Environment: Master Thesis. 2012.
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