While many find joy in seeing bottlenose dolphins (Tursiops truncates) jump and swim in pods of hundreds in coastal environments, researchers turn to them for insight into the health of the ocean.
In a new study published in PLOS ONE, researchers used blood tests to identify alterations in gene expression for bottlenose dolphins in the Gulf of Mexico from 2013 to 2018. These findings reflect the impact of the 2010 Deepwater Horizon disaster and report the health impacts of bottlenose dolphins in Barataria Bay, LA. The impacts include stress response along with reproductive, pulmonary, cardiac and immune function, according to the study.
It’s a “step forward for health assessments in developing molecular markers of health and exposure that can be applied to enhance assessment and characterization of stress-related disease in dolphins,” writes the authors of the study.
As a top predator feeding on squid, fish, crustaceans and cuttlefish, bottlenose dolphins keep their ocean environment in balance. They can be found around the world, including in the U.K., mainly sticking close to coastlines.
They can live for up to 40 or 60 years, and their bodies can absorb toxins in the water. This makes bottlenose dolphins vulnerable to human disturbances, such as feeding, or underwater noise, and larger threats, like recreational or commercial fishing and oil spills.
However, they are not endangered or threatened. Their strong connection to their environment gives researchers insight into the ocean's health.
The goal of this new study was to identify molecular markers to further investigate and help researchers and wildlife veterinarians assess the dolphins’ health, according to the study.
By using tests to assess the blood chemistry of these dolphins, researchers identified many disease conditions after the oil spill. Tests include complete blood counts, stress and reproductive hormone levels. Diseases included inflammation, altered immune status, lung disease, impaired stress response and reproductive failure, according to the study.
They analyzed gene expression, which is a common practice in human and veterinary medicine. A useful tool, these sensitive markers can measure health issues earlier than physical observations of disease or exposure, according to the study. Researchers can also provide health information without the need for a full physical assessment of the animal.
“With further research, biomarkers may be developed that can provide critical health information to wildlife veterinarians, researchers, managers and other stakeholders, even in the absence of full veterinary assessments,” conclude the authors of the study.