Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, Queensland 4222, Australia.
Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, Queensland 4222, Australia.
Ecotoxicol Environ Saf. 2022 Aug;241:113729. doi: 10.1016/j.ecoenv.2022.113729. Epub 2022 Jun 3.
Coastal ecosystems such as those in the Great Barrier Reef (GBR) lagoon, are exposed to stressors in flood plumes including low light (caused by increased turbidity) and agricultural pesticides. Photosystem II (PSII)-inhibiting herbicides are the most frequently detected pesticides in the GBR lagoon, but it is not clear how their toxicity to phototrophic species depends on light availability. This study investigated the individual and combined effects of PSII-inhibiting herbicide, diuron, and reduced light intensity (as a proxy for increased turbidity) on the marine diatom, Phaeodactylum tricornutum. Effective quantum yield (EQY) and cell density were measured to calculate responses relative to the controls over 72-h, in tests with varying stressor intensities. Individually, diuron concentrations (0.1-3 μg l) were not high enough to significantly reduce growth (cell density), but led to decreased EQY; while, low light generally led to increased EQY, but only reduced growth at the lowest tested light intensity (5 μmol photons m s) after 48-hours. P. tricornutum was less affected by diuron when combined with low light scenarios, with increased EQY (up to 163% of the controls) that was likely due to increased electron transport per photon, despite lesser available photons at this low light intensity. In contrast, growth was completely inhibited relative to the controls when algae were simultaneously exposed to the highest stressor levels (3 μg l diuron and 5 μmol photons m s). This study highlights the importance of measuring more than one biological response variable to capture the combined effects of multiple stressors. Management of water quality stressors should consider combined impacts rather than just the impacts of individual stressors alone. Reducing suspended sediment and diuron concentrations in marine waters can decrease harmful effects and bring synergistic benefits to water quality.
沿海生态系统，如大堡礁（GBR）泻湖的生态系统，容易受到洪水羽流中的压力因素的影响，包括低光照（由浊度增加引起）和农业农药。PSII 抑制型除草剂是在 GBR 泻湖中最常检测到的农药，但尚不清楚其对光养生物的毒性如何取决于光的可利用性。本研究调查了 PSII 抑制型除草剂，即敌草隆，以及低光照强度（作为浊度增加的替代物）对海洋硅藻三角褐指藻的单独和联合影响。在不同胁迫强度的测试中，通过测量有效量子产量（EQY）和细胞密度，相对于对照计算了 72 小时内的响应值。单独使用时，敌草隆浓度（0.1-3μg l）不足以显著降低生长（细胞密度），但导致 EQY 降低；而低光照通常会导致 EQY 增加，但仅在最低测试光照强度（5 μmol 光子 m s）下 48 小时后才会降低生长。当与低光情景结合使用时，敌草隆对三角褐指藻的影响较小，EQY 增加（高达对照的 163%），这可能是由于在低光照强度下，每个光子的电子传递增加，尽管可用的光子较少。相比之下，当藻类同时暴露于最高胁迫水平（3μg l 敌草隆和 5μmol 光子 m s）时，与对照相比，生长完全受到抑制。本研究强调了测量多个生物响应变量以捕获多个胁迫因素的综合影响的重要性。水质胁迫因素的管理应考虑综合影响，而不仅仅是单个胁迫因素的影响。减少海洋水中的悬浮泥沙和敌草隆浓度可以降低有害影响，并为水质带来协同效益。
