Abstract
Red tides along Florida’s southwest coast, most commonly formed by the dinoflagellate Karenia brevis, are known for the harmful nature of blooms. K. brevis cells produce a suite of highly potent ichthyotoxins known as brevetoxins which have detrimental effects on coastal communities. When exposed to K. brevis blooms, organisms (e.g., various fish and suspension feeding invertebrate species) can accumulate and metabolize brevetoxins in their tissues. Previous research indicates the highest concentrations are measured in the liver, suggesting it may be a key route for elimination, but no studies have assessed potential long-term persistence. The environmental stability and persistence of brevetoxin in environments long after a bloom has dissipated can lead to lingering effects or even chronic exposure. This study aims to identify persistence of brevetoxins in live fish and invertebrate species inhabiting the coastal waters of southwest Floridafollowing bloom events (> 100,000 cells L-1). Though no blooms were present during sampling times, background concentrations were present within 10 nautical miles of the sampling area. Utilizing enzyme-linked immunosorbent assay (ELISA) kits to test liver and animal tissues for brevetoxin content, brevetoxins were detected in all 81 specimens analyzed. PbTx-3 is the most common congener of brevetoxin and is the focus of this study, typically presented as PbTx-3 equivalents by ELISA. Species demonstrated high variability of brevetoxin concentrations but overall, even with background concentrations present throughout the study, exhibited differences in toxin content over time. Trophic level comparisons may be more complex than originally thought and species-specific differences may play a larger role in toxin accumulation and depuration. Differences in species life history, diets, and mechanistic ability to process brevetoxins may better explain trends seen in coastal communities.
