Department of Biology and Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal.
Department of Environment and Planning and Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, Portugal.
Sci Total Environ. 2021 Jun 1;771:144813. doi: 10.1016/j.scitotenv.2020.144813. Epub 2021 Jan 27.
Wildfires are an important environmental problem in forested watersheds and can significantly alter water quality. Besides the reported ecotoxicological effects on pelagic species, the accumulation of post-fire contaminants in river sediments can also impair the benthic species. In this study, three sediment-dwelling species, Chironomus riparius, Atyaephyra desmarestii and Echinogammarus meridionalis, with different sensitivities, habitats, behaviours and/or feeding strategies, were exposed to water and sediments, in in-situ and in laboratory. Four sites were selected in a partially burnt basin (Alfusqueiro river basin), within and upstream the burnt area. The sites within the burnt area showed higher metal burden in both water and sediment, as well as changes in water physico-chemistry, consistently with the typical effects of incoming post-fire runoff. Both in-situ and laboratory exposures to water and sediments affected by the wildfire induced post-exposure feeding inhibition in the three tested macroinvertebrates. In fact, laboratory and field bioassays have produced generally consistent post-exposure feeding inhibition responses, but the most impactful response could be recognised after in-situ bioassays at the river site within the burnt area, where the species respond to the physico-chemical fluctuations during the exposure period. This comparative perspective supports the importance of using in-situ bioassays as a more realistic approach when dealing with complex and intermittent natural samples such as those affected by post-fire runoff. Overall, our results reinforce the awareness about the negative effects of wildfires on benthic biota, with significant feeding depression and consequent reduction in the available energy budget to ensure successful detoxification, growth and reproduction signalling potential trophic and functional disruption at the ecosystem level. In addition, the duality conditions of sediments as a sink and source of contaminants reinforce concerns, as the exposure of benthic organisms may persist in the long term, even after runoff income ceases due to the resuspension of contaminated sediments.
野火是森林流域的一个重要环境问题，它会显著改变水质。除了对浮游物种的已报道的生态毒理学影响之外，火灾后污染物在河底沉积物中的积累也会损害底栖物种。在这项研究中，三种底栖物种——摇蚊科幼虫（Chironomus riparius）、沼虾科沼虾属（Atyaephyra desmarestii）和欧洲螯虾（Echinogammarus meridionalis），它们具有不同的敏感性、栖息地、行为和/或摄食策略，被暴露于原位和实验室条件下的水和沉积物中。选择在一个部分燃烧的盆地（Alfusqueiro 河流盆地）内和燃烧区上游的四个地点。燃烧区内的地点在水和沉积物中均显示出更高的金属负荷，以及水物理化学性质的变化，与典型的火后径流影响一致。原位和实验室暴露于受野火影响的水和沉积物会导致三种测试的大型无脊椎动物在后暴露期间出现摄食抑制。事实上，实验室和现场生物测定产生了一般一致的后暴露摄食抑制反应，但在燃烧区内河流地点的原位生物测定中可以识别出最具影响力的反应，因为在暴露期间，该地点的物种会对物理化学波动做出反应。这种比较的观点支持了在处理复杂和间歇性的自然样本（如受火后径流影响的样本）时，使用原位生物测定作为更现实的方法的重要性。总体而言，我们的结果强化了对野火对底栖生物群负面影响的认识，野火会导致摄食抑制和随后可用能量预算减少，从而确保成功解毒、生长和繁殖，这可能会对生态系统层面的营养和功能造成破坏。此外，沉积物作为污染物的汇和源的双重条件加剧了人们的担忧，因为底栖生物的暴露可能会持续很长时间，即使径流收入由于受污染沉积物的再悬浮而停止。
