Dam removal is an increasingly important method of stream restoration, but most removal efforts are under-studied in their effects. In order to better understand the effects of such removals on the stream ecosystem, we examined changes in stream macroinvertebrate communities from 2011–2016. Comparisons were focused above, below, and before and after the October 2012 removal of the Brown Bridge Dam on the Boardman River in Michigan (USA), as well as to new channel sites created in its former reservoir (2013–2015). Using linear mixed-effect models on the percent abundance of ecologically sensitive taxa (% Ephemeroptera, Plecoptera, Trichoptera (EPT)), total density of all macroinvertebrates, overall taxa richness, and Functional Feeding Groups, along with multivariate analyses on the community matrix, we examined differences in community composition among sites and years. EPT declined downstream of the dam immediately after dam removal, but recovered in the second year, becoming dominant within 2–4 years. Downstream sites before removal had different community composition than upstream sites and downstream sites after removal (p<0.001), while upstream and downstream sites after removal converged towards similarity. New channel (restored) %EPT, density, and taxa richness were not different from upstream sites in any year following removal, but new channel sites were the most distinct in community composition, possessing multiple indicator taxa characteristic of unique new conditions. The invasive New Zealand mud snail (Potamopyrgus antipodarum) was absent from all sites prior to dam removal, but appeared at low densities in upstream sites in 2013, had spread to all sites by 2015, and showed large increases at all sites by 2016. Managers employing dam removal for stream restoration should include post-removal monitoring for multiple years following removal and conduct risk analysis regarding potential effects on colonization of invasive invertebrate species.

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The practice of harvesting fish and crustaceans by using pesticides is understudied and under-reported in tropical inland fisheries yet poses a significant threat to freshwater biodiversity and community health. This research provides a brief review of the practice and an in-depth case study from southeast Nicaragua. In 2019, 86 interviews and 5 focus groups were conducted in remote communities in the Indio Maíz Biological Reserve (IMBR) and nearby surrounding area and combined with 4 years of local Indigenous Rama and Afrodescendent Kriol community forest ranger data. Forest rangers and 74% of interviewees reported that fishing with pesticides occurs in their communities, including both inside the IMBR and in the nearby surrounding area. The practice is primarily used by illegal settlers, and not by Rama and Kriol communities who have rights to the land in the IMBR. It entails the release of liquid pesticides in water or mixing powdered pesticides with corn flour and using the mixture as bait. Of seven chemicals reported, Cypermethrin, Deltamethrin, and Aluminum Phosphide were most common. The use of ichthyotoxic woody plants was more rarely reported. Habitats targeted ranged from swift headwaters to slow pools in small creeks to larger rivers, depending on target species. Main uses reported for the catch were food for family, bait to catch larger fish, and for sale. The main motivation was increased catch efficiency. Many interviewees attributed stomach issues, diarrhea, cough, convulsions, and miscarriage to exposure to poisoned river water. Twenty-five interviewees blamed poisoned rivers for livestock miscarriages or death. Severe local losses of fish and shrimp populations were reported. Rama and Kriol interviewees describe the practice as a threat to their river-based food security. Despite its illegality, no study participant knew a case of pesticide fishing that had been prosecuted. This destructive fishing practice has significant implications for conservation of the intact river systems of the primary rainforests of southeast Nicaragua, and to the local traditional fisheries they support.