Macroinvertebrados como bioindicadores em riacho tropical: uma avaliação de impactos por sedimentação, rompimento de barragem e de recuperação após medidas de restauração

Abstract

Anthropic alterations in aquatic ecosystems demand the implementation of recuperation actions, highlighting ecological restoration projects. The monitoring is an important step to these projects, and the macroinvertebrates application as bioindicators is an important tool, because they are advantageous in comparison to another assessment methods. Thus, the goal was verify the effects of silting, and dam rupture in macroinvertebrate community, in a tropical stream, and assess the answer to an ecological restoration project implementation. The research was conducted in the Campininha stream, that was impacted by anthropic alterations, featured a dam rupture and after all this disturbances was implemented an ecological restoration project. A literature review was conducted to verification of the applicability of macroinvertebrates as bioindicators of silting and in ecological restoration projects assessment. Data was collected before and after the dam rupture, and samplings were done two years after the project implementation began. The macroinvertebrates community was assessed by application of structural and functional feeding indexes and the results analyzed by univariate and multivariate statistic. The literature review showed that the traditional indexes application may be not sensible to indicate impacts related to silting and ecological restoration projects implementation, and it is necessary the utilization of indexes that consider the community composition, organisms sensibility and functional feeding groups and your relations. Before the dam rupture, the macroinvertebrate community was already poor by the silting of the lake and fluvial channel. The dam rupture leaded to the loss of important groups and in the change of the macroinvertebrate community composition, also loss of functional feeding groups and consequently environmental functions. After the ecological restoration project implementation were found another 20 families, however, the traditional indexes were not sensible to indicate changes in macroinvertebrates community. Composition and functional feeding groups indexes showed the stream recuperation process. The sediment characteristics had a community high explanative power showing that the benthic habitat recovery is a factor that guide to a better community answer, even this was not the goal of the restoration project application. The relative short time after the project implementation was enough to point a environmental quality recovery, in contrast with the literature review. However the most studies analyzed was conducted in temperate environments, showing that in tropical environments the recovery dynamics is different. Thus, is necessary a intensification of restoration projects implementation and monitoring to a creation of data bases to guide managers and professionals responsible by the projects elaboration in decision make.

Impacts of sedimentation and dam failure on the macroinvertebrate community in a tropical stream

“…As previously discussed, the Campininha basin had suffered several impacts over time. In 2006, the main use of the watershed was farming, around 70 % of basin area (Pinto, 2018), with damming of the Campininha upstream for animal watering and fish farming. From 2010 onwards, earthmoving began for the construction of a highway and installation of an industry.…”

Contaminação aquática por rejeito de mineração: o caso do desastre ambiental de Mariana (MG)

“…É possível perceber que eles aparecem apenas duas vezes após a contaminação, sendo uma delas um dia depois (26/05), momento em que ainda não havia tempo para a sedimentação gradativa ocorrer. Essa baixa presença de predadores, assim como a sedimentação, favorece a entrada dos grupos como os coletores-catadores, que se tornaram mais expressivos nos momentos iniciais após a contaminação e recolonização do ambiente(PINTO, 2018).Os fatores que envolvem a presença ou ausência de Lepidopteras são muito mais instáveis e complexos que das outras Ordens, pois este táxon é considerado bioindicador, respondendo rapidamente as perturbações, porém possuem hábitos herbívoros que levam a comportamentos e respostas muitas vezes incertos(OLIVEIRA, 2015;HAMMER et al, 1997, KREMEN, 1992. Ainda assim, a presença dessa Ordem em T5, após a contaminação, pode significar um indício de que o ambiente começou um processo de resiliência e retorno à dinâmica inicial.…”

“…Ainda assim, a presença dessa Ordem em T5, após a contaminação, pode significar um indício de que o ambiente começou um processo de resiliência e retorno à dinâmica inicial. No entanto, para tal afirmação, são necessários outros estudos com diferentes abordagens e mais espécies para verificação se o sistema está se recuperando de fato.Referente aos grupos funcionais, a presença de fragmentadores observada apenas em T6 pode ser afetada pela sedimentação, ocasionando sua diminuição, porém, visto que estes se alimentam de matéria orgânica, quando os recursos vegetais já sofreram alguma mudança estrutural, é possível que nesse caso o grau de sedimentação possa ter favorecido o aumento da matéria orgânica, tornando o ambiente mais propício para alimentação desse grupo, somado a baixa quantidade de predadores(PINTO, 2018;CUMMINS et al, 1989). maior riqueza de espécies de macrófitas aquáticas, constituindo-se em um ambiente mais diversificado estruturalmente e funcionalmente para a comunidade zooplanctônica e de macroinvertebrados bentônicos.…”