Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
J Photochem Photobiol B. 2017 Jun;171:125-132. doi: 10.1016/j.jphotobiol.2017.05.006. Epub 2017 May 6.
Effective ecotoxicological risk assessments for herbicides in tropical marine environments are restricted by a lack of toxicity data, sensitive test methods and endpoints for relevant species, and this requires rectification. The symbiotic sea anemone Exaiptasia pallida is a suitable test species, representing the phylum Cnidaria and allowing for assessments of toxicological responses of both the animal host and in-hospite Symbiodinium spp. Pulse amplitude modulated (PAM) chlorophyll-a fluorometry is recognised as a valuable ecotoxicological tool, and here newly-developed test methods are presented using PAM fluorometry to measure herbicide effects on photosynthetic efficiency of in-hospite Symbiodinium spp. Additionally, measurements on healthy laboratory-reared E. pallida provide baseline data demonstrating the normal effective quantum yield (EQY) and the maximum electron transport rate (ETR) for Symbiodinium spp. in the absence of herbicide stress. Concentration-dependant reductions in the EQY and ETR occurred during diuron and atrazine exposures; a mean 48-h EC50 (effective concentration; 50%) of 8μg/L of diuron was estimated, however atrazine elicited a much lower toxicity. Twelve-day exposures to 10-200μg/L diuron showed that the greatest EQY effect occurred during the first 48h, with little subsequent change. However, longer exposures to the lowest diuron treatment (1μg/L) showed the lowest EQYs after 96h followed by recovery to control levels within 12d. Furthermore, asexual reproduction was inhibited during 12-d exposures to diuron, and 12-d EC50 values of 100 and 132μg/L were estimated to inhibit successful reproduction of pedal lacerates and juveniles by 50% respectively. This study provides much needed data contributions to species sensitivity curves for development of diuron and atrazine water quality guidelines in tropical marine environments.
有效评估热带海洋环境中除草剂的生态毒性受到毒性数据、敏感测试方法和相关物种终点的缺乏的限制，这需要加以纠正。共生海葵 Exaiptasia pallida 是一种合适的测试物种，代表刺胞动物门，允许评估动物宿主和体内共生 Symbiodinium spp 的毒理学反应。脉冲幅度调制（PAM）叶绿素荧光法被认为是一种有价值的生态毒理学工具，这里提出了新开发的测试方法，使用 PAM 荧光法测量除草剂对体内共生 Symbiodinium spp 光合作用效率的影响。此外，对健康的实验室培养的 E. pallida 进行的测量提供了基线数据，证明了体内共生 Symbiodinium spp 在没有除草剂胁迫的情况下的正常有效量子产量（EQY）和最大电子传递率（ETR）。在与 Diuron 和 Atrazine 接触期间，EQY 和 ETR 呈浓度依赖性降低；估计 Diuron 的 48 小时 EC50（有效浓度；50%）为 8μg/L，但 Atrazine 的毒性要低得多。12 天暴露于 10-200μg/L 的 Diuron 表明，最大的 EQY 效应发生在最初的 48 小时内，随后变化很小。然而，在最低的 Diuron 处理（1μg/L）下进行更长时间的暴露后，在 96 小时后出现最低的 EQY，然后在 12 天内恢复到对照水平。此外，无性繁殖在 Diuron 的 12 天暴露期间受到抑制，估计 12 天 EC50 值为 100 和 132μg/L 分别抑制足蹼撕裂和幼体成功繁殖的 50%。本研究为热带海洋环境中 Diuron 和 Atrazine 水质标准的发展提供了急需的物种敏感性曲线数据贡献。
