Scientists with NOAA’s National Centers for Coastal Ocean Science (NCCOS) continue to assess environmental and estuarine health of South Carolina’s Charleston Harbor through non-traditional methods of collecting dolphin respiratory data. Using an unoccupied aircraft system (UAS) equipped with four petri dishes or by holding a pole mounted with a petri dish over the dolphins, scientists are able to collect spray from their blow exhalations while allowing the dolphins to continue their natural activities uninterrupted.
For this mission, NCCOS scientists and a College of Charleston student sampled dolphins in the Wando River–the northeast reach of the Charleston Harbor–an area that had not yet been sampled for blow exhalations. This excursion provided the team with an opportunity to train additional team members in the pole sampling method, which uses a petri dish attached to a boat hook pole. The team was surprised to find approximately 30 dolphins spread out over a large portion of the river, as dolphins typically gather more near the Charleston Harbor entrance and confluence of large rivers during the winter months. While cruising the river, three juvenile dolphins began to ride the bow, providing the team with the opportunity to collect three blow samples from the pole. In addition, the team collected a blow exhalation sample using the UAS.
The Charleston Harbor is home to one of the largest ports on the east coast, several military bases, and industrial complexes, causing a strain to the overall health of the estuary and wildlife that depends on the ecosystem. In addition, many aquatic species that commercial and recreational fishermen rely on for food and their livelihoods spend a portion of their life within the estuary.
Over the past 20 years, many dolphins within the Charleston Harbor have been observed moving into waters with low salinity. This behavior often requires dolphins to be rescued and some display signs of poor health. A previous study conducted by NCCOS and a College of Charleston graduate student showed that dolphins using low salinity do so during times of higher water temperatures, typically from spring to early fall (Principe et al.2023).
Recent findings from these sample collections show that blow exhalation samples can be distinguished from water and air microbiome samples that are simultaneously collected after a blow exhalation sample is collected. Further, while dolphin exhalations are incredibly diverse with microbes, species of the genus Streptococcus, Pseudomas, and Porphyromonas have human zoonotic potential and were commonly found in recent blow samples.