Effects of the toxic dinoflagellate Karenia brevis on the development of the marine gastropod Crepidula fornicata

Abstract

With harmful algal blooms increasing in frequency and range, it is important to study how exposure to harmful algae may affect the development of marine organisms. Our studies examined the susceptibility of the early life stages of the Atlantic slipper limpet Crepidula fornicata to the toxic red tide dinoflagellate Karenia brevis (strain FWC1010), testing the effects of exposure to 3 algal bloom concentrations (100, 1000, or 5000 cells ml-1), representing medium to high bloom conditions in nature, on survival, growth, clearance rates, metamorphosis, and post-metamorphic survival and growth. Larvae were given either a mixed diet of K. brevis together with the non-toxic phytoplankton Tisochrysis lutea (clone TISO), a unialgal diet of K. brevis, or a control diet of unialgal TISO. In some experiments, larvae were raised to metamorphosis on the different diets and were then observed as juveniles in a non-toxic environment to see if there were any latent effects of larval exposure to K. brevis on subsequent juvenile survival or growth (in terms of both shell length and percent inorganic weight). There were no significant effects of larval exposure to K. brevis on larval or juvenile survival. However, we observed several notable sub-lethal effects of larval exposure to high K. brevis concentrations (1000 and 5000 cells ml-1), including slower larval shell growth rates, delayed competence for metamorphosis, lower responses to natural metamorphic cues, and reduced rates of post-metamorphic growth (in terms of both shell length per day and percent inorganic weight) when juveniles were reared under control conditions.