Automated image systems to characterize aquatic organisms improve research and enable fast response to environmental risk situations. In November 2015, a dam in Mariana City-MG (Brazil) collapsed and led to the dispos...Automated image systems to characterize aquatic organisms improve research and enable fast response to environmental risk situations. In November 2015, a dam in Mariana City-MG (Brazil) collapsed and led to the disposal of mud tailings from the mining process to the Doce River. The accident resulted in several casualties and incalculable damage to surrounding communities and the environment. The mud increased water turbidity, an essential condition to the functioning of the image analysis systems, and directly affected the characterization of the organisms, making it impossible to distinguish copepods in the mud, due to the blurred outline. To get a quick response evaluating environmental situations, this work aimed to develop and test different algorithms characterizing and classifying copepods by their size (length and area) using in situ images acquired by the Lightframe On-Sight Keyspecies Investigation device. Field tests were carried out under different turbidity levels throughout the gradient observed in the coastal zone adjacent to the Doce River. The best algorithm reduced nearly 50% of the noise in some images when compared with manual treatment and led to 96% accuracy in measurement and counting. Semi-automated devices that perform post-processing corrections are suitable for fast environmental evaluation under high turbidity scenarios.展开更多
Riverscape connectivity is a critically important component determining the ecological condition of lotic ecosystems.We evaluated changes in fish assemblages caused by the loss of connectivity by mine tailings storage...Riverscape connectivity is a critically important component determining the ecological condition of lotic ecosystems.We evaluated changes in fish assemblages caused by the loss of connectivity by mine tailings storage dams(TSDs),hypothesizing that headwater fish assemblages are restructured by TSDs located downstream,even though the upstream habitats are not altered.We used standard methods to collect fish in 24 first to third order sites,with half draining to TSDs(dammed)and the other half free from this impact(undammed).To identify differences between treatments,we used PERMANOVA to test both environmental variables and ichthyofauna composition(Bray-Curtis similarity index)and evaluated the biological metrics that most influenced assemblage composition change.As expected,we observed no difference between treatments for environmental variables,but we did observe differences in fish assemblage composition.We also observed five metrics with lower values in dammed streams(richness and abundance of intolerant species,siluriform richness,and abundance of Pareiorhaphis cf.proskynita and Trichomycterus brasiliensis)and two metrics with higher values in dammed streams(perciform richness and abundance of Oligosarcus argenteus).We believe these changes resulted from of stream fragmentation by TSDs,in addition to source-sink mechanisms and conclude that mine TSDs located downstream change headwater fish assemblages,an impact often neglected in biomonitoring and bioassessment studies.展开更多
文摘Automated image systems to characterize aquatic organisms improve research and enable fast response to environmental risk situations. In November 2015, a dam in Mariana City-MG (Brazil) collapsed and led to the disposal of mud tailings from the mining process to the Doce River. The accident resulted in several casualties and incalculable damage to surrounding communities and the environment. The mud increased water turbidity, an essential condition to the functioning of the image analysis systems, and directly affected the characterization of the organisms, making it impossible to distinguish copepods in the mud, due to the blurred outline. To get a quick response evaluating environmental situations, this work aimed to develop and test different algorithms characterizing and classifying copepods by their size (length and area) using in situ images acquired by the Lightframe On-Sight Keyspecies Investigation device. Field tests were carried out under different turbidity levels throughout the gradient observed in the coastal zone adjacent to the Doce River. The best algorithm reduced nearly 50% of the noise in some images when compared with manual treatment and led to 96% accuracy in measurement and counting. Semi-automated devices that perform post-processing corrections are suitable for fast environmental evaluation under high turbidity scenarios.
基金supported by a scholarship to GNS from the Coordenacao de Aperfeicoamento de Pessoal de Nível Superior(CAPES)(Code 001)Fundacao de Amparoa Pesquisa do Estado de Minas Gerais(FAPEMIG APQ-00401-19).RMH received a Fulbright-Brasil Distinguished Scholar grantthe National Council for Scientific and Technological Development(CNPq)for research productivity fellowships(RL#312531/2021-4,LFAM#302406/2019-0).
文摘Riverscape connectivity is a critically important component determining the ecological condition of lotic ecosystems.We evaluated changes in fish assemblages caused by the loss of connectivity by mine tailings storage dams(TSDs),hypothesizing that headwater fish assemblages are restructured by TSDs located downstream,even though the upstream habitats are not altered.We used standard methods to collect fish in 24 first to third order sites,with half draining to TSDs(dammed)and the other half free from this impact(undammed).To identify differences between treatments,we used PERMANOVA to test both environmental variables and ichthyofauna composition(Bray-Curtis similarity index)and evaluated the biological metrics that most influenced assemblage composition change.As expected,we observed no difference between treatments for environmental variables,but we did observe differences in fish assemblage composition.We also observed five metrics with lower values in dammed streams(richness and abundance of intolerant species,siluriform richness,and abundance of Pareiorhaphis cf.proskynita and Trichomycterus brasiliensis)and two metrics with higher values in dammed streams(perciform richness and abundance of Oligosarcus argenteus).We believe these changes resulted from of stream fragmentation by TSDs,in addition to source-sink mechanisms and conclude that mine TSDs located downstream change headwater fish assemblages,an impact often neglected in biomonitoring and bioassessment studies.
