Effects of different temperatures on the physiological and toxigenic characteristics of Prorocentrum lima

Prorocentrum lima, a harmful microalga with potential red-tide-forming capability, is widely distributed worldwide and poses a potential threat to marine ecosystems and fishery resources due to its toxin production. Therefore, it is of great practical significance to assess the potential ecological risks of P. lima and to study the influence of environmental factors on its growth and toxin production characteristics. In this study, P. lima strain CMCC405 was used to investigate the effects of different temperatures (15 ℃, 20 ℃, and 25 ℃) on its physiological characteristics (e.g., growth cycle and cell density) and the production of intracellular and extracellular toxins. Results showed that temperature significantly influenced the growth and toxin production of P. lima. At 15 ℃ and 25 ℃, the growth of P. lima was slow, without a distinct exponential growth phase. In contrast, at 20 ℃, strain CMCC405 exhibited relatively favorable growth, with typical lag, exponential, and stationary phases. Over the whole 70-day growth period, algal density and toxin content showed a significant positive correlation (P＜0.05), with the highest toxin production occurring during the stationary phase. Under all three temperature conditions, P. lima CMCC405 primarily produced okadaic acid (OA) and dinophysistoxin-1 (DTX1), with intracellular toxin levels consistently higher than extracellular toxin levels. Comparison with extracellular toxin content indicated that the solid phase adsorption toxin tracking (SPATT) technique can accurately reflect the levels of diarrhetic shellfish poisoning (DSP) released into the water, which makes it suitable for monitoring the release and production of extracellular toxins of P. lima. This study provides a scientific basis for the risk assessment and monitoring of P. lima toxicity in coastal waters.