Prolonged exposure to freshwater is linked to adverse health conditions, immune deficiencies, and even dolphin deaths, but there’s still a lot we don’t understand.
SDRP Post-doctoral Scientist Dr. Christina Toms was conducting photo identification surveys in Pensacola Bay, Florida, as part of an ongoing study to provide the first comprehensive assessment of population dynamics for bottlenose dolphins in that system in 2014 when the city experienced historic rainfall.
According to some estimates, 24 inches of rain fell over the area in just 24 hours — an extreme influx of freshwater into Pensacola Bay. This natural disaster led to a “natural” experiment: Would the surge of freshwater into the Bay — and the dolphins’ subsequent prolonged exposure to it — lead to an increase in skin lesions?
Surprisingly — and contrary to expectations — a widespread outbreak of skin lesions did not seem to materialize despite the fact that salinities in the Bay remained low for months. Instead, only a handful of individuals exhibited extensive skin lesions that in some cases persisted or worsened over time.
Toms and her coauthors discuss the implications in “Skin lesion and mortality rate estimates for common bottlenose dolphin (Tursiops truncatus) in the Florida Panhandle following a historic flood” recently published in the journal PLOS One. The study shows that the factors that determine whether flooding and freshwater exposure will lead to serious health concerns — or result in mild responses — are still poorly understood.