Effects of the Florida red tide dinoflagellate, Karenia brevis, on oxidative stress and metamorphosis of larvae of the coral Porites astreoides

Abstract

Florida red tides, caused by the dinoflagellate Karenia brevis, produce a series of neurotoxins, brevetoxins, which have historically had a negative impact on coastal communities along the South Florida coast. While much work has examined the effects of K. brevis blooms or exposure to brevetoxins on a diverse array of marine organisms, there have been no reports studying the impact of K. brevis on coral physiology. We provide evidence that short-term exposure of naturally occurring concentrations of K. brevis and their associated toxins can induce oxidative stress in the coral larvae of Porites astreoides. Larvae of P. astreoides were exposed to aliquots of intact K. brevis cells at naturally occurring concentrations (6 × 10 5 – 4 × 10 6 cells L −1) or cellular lysates (containing 5.4–15.0 μg L −1 brevetoxin) for 20 h and a variety of larval physiological biomarkers were measured. In the presence of bloom scale concentrations of K. brevis larval respiration of P. astreoides was inhibited. This was accompanied with an increase in lipid hydroperoxide content and catalase activity indicating oxidative damage and a subsequent antioxidant response were occurring. However, when larvae were exposed to intact cells of K. brevis or their sonicated, lysed exudates stress indices including zooxanthellae expulsion (bleaching), larval protein carbonylation, and superoxide dismutase activity were not significantly altered. Even though there was evidence for short-term oxidative stress in larvae that were exposed to K. brevis there was no change in survival or settlement rates of larvae of P. astreoides.