Harmful algal blooms formed by the mixotrophic dinoflagellate Akashiwo sanguinea are toxic to multiple aquatic organisms, although the relationship between toxicity and grazing is unknown. In this study, the effects of irradiance and nutrient levels on the grazing rate of A. sanguinea on the cryptophyte Rhodomonas salina were investigated using an optimized stable isotope method. Under light-limited conditions (0–30 μmol photons m −2 s −1 ), A. sanguinea exhibited higher hemolytic activity and grazing rate. Under the same level of irradiance, the growth and respiration rates were higher in co-culture treatments, while the oxygen release rate was higher in monoculture treatments. The growth rate, hemolytic activity, and grazing rate of A. sanguinea increased significantly with higher nutrient levels or an unbalanced N:P ratio. The hemolytic activity and grazing rate were higher in urea treatment, while the growth rate was higher in ammonia treatment. This study suggests that toxicity is involved in the feeding process of the mixotrophic dinoflagellate A. sanguinea ; the unique feeding flexibility adapting to low irradiance, increased nutrients, unbalanced N:P ratio, and organic nitrogen urea gains an advantage in interspecific competition among phytoplankton.
Fulin Yang,Hongjie Liu,Hao Fu,Chaoxin Zhang,Changrui Ye,Shaopeng Wang,Man Zhang,Fang Shen,Liwei Wang
As one of the significant algal bloom species, Akashiwo sanguinea has long brought challenges to controlling red tide. Red tide outbreaks are often accompanied by the mass propagation of various algal bloom species, which brings problems to investigating red tides using traditional optical methods. Electrochemical biosensing technology has high sensitivity and specificity, yet its use in detecting A. sanguinea DNA in sea areas is insufficient. Here, the amplification system combining Nt.BbvCI endonuclease-assisted and hybridization chain reaction (HCR) has a detection limit of the same or even lower magnitude than other HCR systems. More importantly, the auxiliary short strands from the Nt.BbvCI system activates HCR, reducing the steric hindrance of long DNA molecules and enhancing HCR’s activity. Thus, the portable electrochemical biosensor based on this system successfully detected simulated A. sanguinea DNA samples, with a limit of detection (LOD) at 1.53 fg/μL and a limit of quantification (LOQ) at 4.27 fg/μL, far better than traditional optical-based methods. Also, the predicted cell density of A. sanguinea generally matches that of optical microscopy. This portable biosensor is expected to conduct an on-site investigation of A. sanguinea ’s cell density. It can provide data support for early warnings of red tide outbreaks and reduce the time needed for investigations.
Tiantian Chen,Jiaqi Chen,Wenlong Dong,Shuqun Song,Weijun Tian,Caiwen Li
As emerging contaminants, benzotriazole ultraviolet stabilizers (BUVSs) have been frequently detected in aquatic environments, which usually co-occur with heavy metals and cause complex toxicity to aquatic organisms. However, the specific role of BUVSs in the combined toxicity remains poorly understood. Herein, a harmful marine dinoflagellate Akashiwo sanguinea was used to explore the individual and combined toxicities of UV-234 and cadmium (Cd 2+ ). Exposure to UV-234 at an environmental concentration (10 μg L −1 ) slightly inhibited algal growth ( P > 0.05). Individual exposure to both low (1.77 mg L −1 ) and high (5.30 mg L −1 ) concentrations of Cd 2+ significantly impaired algal photosynthesis by altering photosynthetic pigments, disrupting energy absorption, dissipation and trapping, reaction center activation, and electron transport, thereby inducing oxidative stress, and up-regulated pyruvate metabolism and the tricarboxylic acid cycle. Notably, co-exposure with UV-234 mitigated the toxic effects induced by Cd 2+ , and caused weaker inhibition of algal growth via inducing less substantial oxidative damage. These findings highlight the significant influence of UV-234 and Cd 2+ co-exposure on marine dinoflagellates, providing new insights into the joint toxicity mechanisms and a scientific basis for environmental risk assessment of emerging BUVSs.
危险品化学品经营许可证（带存储）