Description
The effect of temperature on physiology and toxicity of the benthic dinoflagellates Coolia spp. isolated from Hong Kong watersMeng Yan1,2, Priscilla T.Y. Leung*1,2, Jiarui Gu1,3, Xin Li1,3, Veronica T.T. Lam1, Tak-Cheung Wai1,2, Sam K.F. Yiu1, Paul K.S. Lam*1,2,3
1State Key Laboratory in Marine Pollution, City University of Hong Kong, Hong Kong, China
2Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
3Department of Chemistry, City University of Hong Kong, Hong Kong, China
* Correspondence: [email protected] ; [email protected]
Abstract
The emerging threat of benthic and epiphytic toxic algae (BETA) to marine ecosystems has attracted worldwide attention. Seawater temperature is one of the major factors influencing the growth and distribution of BETA. Coolia spp. are one of the cosmopolitan group of BETA, and are potentially toxic. In this study, we aimed to elucidate the effect of different seawater temperatures on physiological performance, toxicity, toxin production and molecular responses of C. malayensis (a toxic species) and C. canariensis (a less toxic species). Coolia monocultures were exposed to 7 temperatures i.e., 16, 18, 20, 22, 24, 26 and 28°C for more than 5 generations before sampled for growth curves determination, photosynthesis efficiency, phaeo-pigments amount measurement, bioassay, toxin analysis and gene expression. Our results showed that the optimal temperature for growth of C. malayensis was 24°C while its photosynthesis was steady across the range of temperatures. The growth rate of C. canariensis was highest at 20°C. Lower temperatures, i.e., 16 and 18°C inhabited its growth and photosynthesis. The amount of phaeo-pigments (in 1 x 105 cells) reached the highest at 26°C for both C. malayensis (3.06 µg/ml) and C. canariensis (15.61 µg/ml), but the level reached the lowest at 20°C for C. malayensis (0.90 µg/ml) and at 16°C for C. canariensis (2.76 µg/ml). The bioassay with Artemia larvae showed that the 48 h LC50 values of C. malayensis decreased as temperature increased. The current results suggested that Coolia may produce more pigments and toxins as temperatures increased. Our preliminary analytic analysis showed that C. malayensis produces okadiac acid (OA) and dinophysistoxin 1 (DTX1). With more upcoming results on toxin analysis and transcriptome profiles, we could have gain further insight on possible mechanisms that would associate with different toxicities of Coolia species due to global changes of seawater temperature.
| Period | 21 Oct 2018 → 26 Oct 2018 |
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| Event type | Conference |