The toxigenic haptophyte Prymnesium parvum is a mixotrophic phytoplankter with an extensive historic record of forming nearly monospecific, high-biomass, ecosystem-disrupting blooms, and it has been responsible for major fish kills in brackish waters and aquaculture facilities in many regions of the world. Little is known about how this species responds to commonly occurring environmental contaminants, or how nutrient (nitrogen, phosphorus) pollution may interact with environmentally relevant pesticide exposures to affect this harmful algal species. Here, standard algal toxicity bioassays from pesticide hazard assessments were used along with modified erythrocyte lysis assays to evaluate how atrazine exposures, imbalanced nutrient supplies, and salinity interact to influence the growth and toxicity in P. parvum isolates from three different regions. In nutrient-replete media, P. parvum 96 h IC₅₀s ranged from 73.0 to 88.3 μg atrazine L⁻¹ at salinity 10 and from 118 to >200 μg atrazine μg L⁻¹ at salinity 20, and the response depended on the strain and the test duration. Relative hemolytic activity, used as an indication of toxicity, was a function of herbicide exposure, nutrient availability, salinity, geographic origin, and interactions among these factors. Highest levels of hemolytic activity were measured from a South Carolina strain in low-nitrogen media with high atrazine concentrations. Herbicide concentration was related to relative hemolytic activity, although a consistent relationship between growth phase and toxicity was not observed. Overall, these findings suggest that increasing chemical contamination is helping to promote ecosystem-disruptive, strongly mixotrophic algal blooms.

有毒的触生植物小球藻是一种混合营养的浮游植物，具有形成近单特异性，高生物量，破坏生态系统的水华的广泛历史记录，它已导致世界许多地区咸淡水和水产养殖设施中的重大鱼类死亡。关于该物种如何应对常见的环境污染物，或者营养物（氮，磷）污染如何与环境相关的农药暴露相互作用以影响这种有害的藻类物种，人们所知甚少。在这里，将农药危害性评估中的标准藻类毒性生物测定法与改良的红细胞裂解测定法一起使用，以评估阿特拉津的暴露，营养物质供应不平衡和盐度如何相互作用，从而影响in鱼的生长和毒性。P. parvum分离物来自三个不同区域。在营养丰富的培养基中，小球藻96 h IC ₅₀ s在盐度10时为73.0至88.3μg阿特拉津L ^-1，而在118至> 200μg阿特拉津L g- ¹在盐度为20时，响应取决于应变和测试持续时间。相对溶血活性（用作毒性指标）是除草剂暴露，养分利用率，盐分，地理来源以及这些因素之间相互作用的函数。从南卡罗来纳州菌株在高at去津浓度的低氮培养基中测得的最高溶血活性水平。除草剂浓度与相对溶血活性有关，尽管未观察到生长期与毒性之间的一致关系。总体而言，这些发现表明，化学污染的增加正在促进破坏生态系统的，强烈混合营养的藻华。