Effect of increasing sea water temperature on the growth and toxin production of the benthic dinoflagellate Prorocentrum lima

In future decades, harmful algae blooms may increase in frequency in aquatic environments as a result of higher global temperatures (warming). This study tested the hypothesis that cell growth rate and Diarrethic Shellfish Poisoning (DSP) toxin (okadaic acid, OA; dinophysistoxin 1, DTX1) per cell of the benthic dinoflagellate Prorocentrum lima increases with temperature. P. lima cells were grown in f/2 medium at irradiances of 50 ± 15 µmol m −2 s −1 and photoperiod of 12 h L:12 h D. Cell abundance, photosynthetic efficiency ( Fv / Fm ), and nutrient consumption (NO 3 − + NO 2 − and PO 4 3− ) were also determined. P. lima optimum growth temperature was at 15 and 25°C but the highest Fv / Fm values showed no association to the maximum growth rate . P. lima showed lower cell growth rates and Fv / Fm values at both 5 and 30°C. Only free OA concentration per cell showed an increase with temperature up to 15°C. Highest lipophilic toxicity in P. lima was found during the stationary growth phase at low (10–15°C) and elevated (30°C) temperatures. Results from this study suggest that future changes to climatic conditions in coastal waters may lead to higher growth rates and cellular toxin levels in P . lima populations worldwide.