Aim Understanding the impact of anthropogenic activities is central for supporting management and conservation efforts. In aquatic ecosystems, the construction of dams for hydroelectric power plants is a major environmental change that turns the riverine ecosystem into a reservoir lake. Such environmental deep alteration causes profound impacts in biota. The goal of this study is to make a comprehensive description of zooplankton trajectory following the construction of a reservoir in the transition from the hotspot Cerrado to Amazon, Central Brazil. Methods We used data sampled before, during and after the formation of the reservoir lake in 10 sampling units each period. We evaluated compositional changes, shifts in spatial organization, and a variation in beta-diversity from before to after the dam constructions using a set of multivariate analyses. We evaluated effects for Rotifers, Copepods and Cladocerans separately. Results Compositional changes were evident for all zooplankton groups: Rotifers, Copepods and Cladocerans. Besides, spatial community organization was also affected but depending on the beta-diversity facet and data resolution – mainly turnover using abundance data, except for Copepods. Finally, an increase in nestedness occurred for all groups during the formation of the reservoir lake. Conclusions In summary, our study showed the deep impacts for zooplankton that the formation of a reservoir lake causes. We innovate by making a complete assessment, which indicate clearly the complexity of evidencing impacts in aquatic communities. We also suggest that long-term monitoring should continue in reservoirs for scientific purposes. The changes in biota also make clear that the construction of dams should be accompanied by preservation of other pristine riverine ecosystems.

Absence of the invasive golden mussel in a reservoir near Curitiba, Brazil: A possible case of invasion failure Ausência do mexilhão dourado invasor em um reservatório perto de Curitiba, Brasil: um possível caso de invasão malsucedida This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0), which permits reproduction, adaptation, and distribution provided the original author and source are credited. SHORT COMMUNICATION Fabrício de Andrade Frehse 1

The golden mussel is an aquatic invasive species that was introduced in South America in the '90s, including Brazil, and was firstly registered in 2001 in the Paraná state. This bivalve causes macrofouling issues because adhere in substrates and form dense aggregations, affecting especially hydroelectric power plants, and water treatment facilities, apart from the native biodiversity. The present research aimed to diagnose the distribution of Limnoperna fortunei in the Paraná state using environmental DNA (eDNA) from 174 sites from 12 basins, and scientific and technical previous records. L. fortunei eDNA was found in 90 sites from 11 hydrographic basins sampled. Most of the positive samples were detected in Iguaçu (42), Tibagi (15), and Ivaí (10) rivers basins. We also registered the first occurrence for five basins: Cinzas, Itararé, Ivaí, Pirapó e Ribeira rivers. Together, our and previous data recorded L. fortunei in 118 sites, between adult, larvae, and eDNA detection. Moreover, the results evidenced that eDNA is a low coast and reliable tool, and it may be very recommended for L. fortunei early detection and diagnosis. The present research was the greatest and most widespread survey for golden mussel prospection in a state in Brazil, supported a worrying scenario for Parana, with the urgent need for intense and continuous monitoring and prevention actions for controlling and mitigation of the L. fortunei impacts. HIGHLIGHTS Golden mussel distribution in Paraná, Brazil, through eDNA and previous records. 90 from 178 sampled sites with Limnoperna fortunei DNA presence. Present and previous records support the species occurrence in 118 widespread sites. A worrying scenario and urgent need for prevention, mitigation, and impact control. 2 Borges de Andrade, P.D.; et al.