Is Karenia brevis really a low-light-adapted species?

Publication date: Available online 25 November 2019Source: Harmful AlgaeAuthor(s): Charles L. Tilney, Sugandha Shankar, Katherine A. Hubbard, Alina A. CorcoranAbstractDespite nearly annual blooms of the neurotoxic dinoflagellate Karenia brevis (Davis) G. Hansen and Moestrup in the Gulf of Mexico, defining the suite of biological traits that explain its proliferation has remained challenging. Studies have described K. brevis as a low-light-adapted species, incapable of sustaining growth under high light, which is at odds with observed surface aggregations sometimes within centimeters of the sea surface and also with short-term experiments showing photosynthetic machinery accommodating high irradiances. Here, growth and photophysiology of three K. brevis isolates were evaluated under a range of environmentally relevant irradiances (10–1500 μmol photons m−2 s−1) in the laboratory. No differences in growth–irradiance curves were observed among isolates; all sustained maximum growth rates at the highest irradiances examined, even in exposures as long as three weeks. The growth efficiency α of K. brevis under light-limiting conditions appeared mediocre among dinoflagellates, and poorer than that of other phytoplankton (e.g., diatoms, cyanobacteria), implying that K. brevis is not a low-light specialist. This finding substantially alters earlier parameterizations of K. brevis growth–irradiance curves. Therefore, a model was developed to contextualize how these new gr...
Source: Harmful Algae - Category: Environmental Health Source Type: research