BREVARD COUNTY — A study led by Florida Institute of Technology found the neurotoxin saxitoxin to be present during the bloom and non-bloom periods in the Indian River Lagoon.
According to a press release, Florida Tech assistant professor Spencer Fire, Florida Tech graduate student Jeremy Browning, Wendy Noke Durden and Megan Stolen from Hubbs SeaWorld Research Institute, conducted a study analyzing liver samples from 119 dead-stranded bottlenose dolphins collected from 2002 to 2011.
“We were looking at those animals because we suspected that those toxins should show up somewhere in the food web, but we didn’t know where,” Dr. Fire said. “Probably the most important place to look was in animals that are sort of sentinel species for marine health.”
Saxitoxin has long been associated with mass die-offs of marine mammals during algal blooms, a press release noted. The toxin is produced by Pyrodinium bahamense, a bioluminescent algae found in the Indian River Lagoon.
Dr. Fire, along with his associates, published the study’s findings in an online journal “Aquatic Toxicology” under the title, “Comparison of during-bloom and inter-bloom brevetoxin and saxitoxin concentrations in Indian River Lagoon bottlenose dolphins, 2002-2011.”
The first step is establishing that the neurotoxin is in the lagoon, Dr. Fire said, then researchers can move on to discovering how widespread it may be and which parts of the food web is being exposed to it.
“We actually just finished some data in a bunch of [bottlenose dolphins] and their favorite food items, we can start to make some additional hypotheses about how saxitoxin is actually affecting them, is it harmful or is it harmless concentrations,” Dr. Fire stated.
This study of looking into prey fish was conducted with Harbor Branch Oceanographic Institute over a three-year period.
Dr. Fire explained that in other areas of the U.S. where saxitoxin is abundant, such as in New England or in the Pacific Northwest, it can cause massive die-off events and, due to algal blooms, may be the reason people can’t shellfish at certain times of the year.
Discovering the levels of saxitoxin in bottlenose dolphins will offer researchers a point of reference to compare toxin values in future dolphin die-offs.
Florida Tech faculty has recently submitted a grant proposal to the National Oceanic and Atmospheric Administration.
“It was a mitigation strategy to see if you can actually reduce the impact by chemically converting the phytoplankton cells and feed them in the water as a way to absorb living cells and their toxins,” Dr. Fire said.
To read the study by Dr. Fire and his colleagues, visit www.sciencedirect.com/science/article/pii/S0166445X19307040