When roads cross streams: fish assemblage responses to fluvial fragmentation in lowland Amazonian streams

Irrigation dams threaten Brazilian biodiversity

Brazil is among the main contributors to global biodiversity, which, in turn, provides extensive ecosystem services. Agriculture is an activity that benefits greatly from these ecosystem services, but at the same time is degrading aquatic and terrestrial ecosystems and eroding Brazilian biodiversity. This conflict is growing, as emerging unsustainable legislative proposals that will benefit the agricultural sector are likely to accelerate the decline of biodiversity. One such initiative (Bill 1282/2019) would change Brazil's "Forest Code" (Law 12,651/2012) to facilitate construction of irrigation dams in Permanent Preservation Areas, a category that includes strips (with or without vegetation) along the edges of watercourses. Two other similar bills are advancing through committees in the Chamber of Deputies. Here we provide details of these three bills and discuss their consequences for Brazil's biodiversity if they are approved. Expected negative impacts with changes in the legislation include: increased deforestation; siltation; habitat fragmentation; introduction of non-native species; reduction in the availability of aquatic habitats; and changes in biogeochemical process. These proposals jeopardize biodiversity and may compromise the negotiations for an agreement between Mercosur and the European Union.

Does land use and land cover affect adult communities of Ephemeroptera, Plecoptera and Trichoptera (EPT)? A systematic review with meta-analysis

We conducted a systematic review to better understand this gap and analyzed i) in which global regions are studies usually conducted, ii) the taxon studied, iii) sampling methods and iv) how authors collaborated in these studies. We also tested the relationship between different types of land use and land cover and adult EPT communities using a meta-analysis. We searched for relevant articles on the website Web of Science, using specific words related to the subject. We found 454 papers and selected 31 of them for the scientometric analysis, as they were in accordance with our objectives, and eight for the meta-analysis. Among this subset, we observed that study areas and collaborations among authors were largely restricted to a few countries in Europe and North America. Most studies used the group Trichoptera, probably due to its diversity and the longevity of the adults compared to other groups. Light traps were the most common sampling method, most likely due to their efficiency in capturing flying insects with nocturnal habits. The greatest differences in adult EPT communities were found between open areas (moorland and prairie) and forest areas. This result indicated that the conversion of forest habitats into open areas negatively impacts adult EPT communities. Our systematic review can be an important tool to help researchers choose appropriate collection methods and taxonomic groups to work with in studies on impacts of land use change on adult EPT communities.

Seizing resilience windows to foster passive recovery in the forest-water interface in Amazonian lands

Forest regeneration has increased in many tropical abandoned lands and current restoration commitments in this region aim to restore over 1,400,000 km² of degraded land by 2030. Although regenerating forests recover biomass, biodiversity, and processes with time, the recovery trajectories may be uncertain due to past disturbances. Currently, there is a lack of knowledge to sustain the effectiveness of passive regeneration for the recovery of riparian forests and the adjacent waterbodies in the tropics, which may compromise the outcomes of ongoing and future tropical riparian restoration programs. We evaluated the drivers of riparian forest structural recovery and how this relates to stream conditions in 12 abandoned pasturelands in eastern Brazilian Amazonia. These pasturelands range across regeneration age (pasture (PA) - 0 to 4 years; young regeneration (YR) - 8 to 12 years; old regeneration (OR) - 18 to 22 years) and years of past land-use (PA - 23.25 average years of past land-use, YR - 18.25, OR - 7). We compared the conditions of these sites to 4 reference sites with conserved forests (REF, >100 years), where there was no recorded pasture use in the past. Short-term responses of forests and streams to passive regeneration indicated high ecosystem resilience after low to intermediate past land-use intensity, reflected in the improvement of stream ecosystems. Such high resilience is possibly attributable to low- to intermediate-intensity pasture-related disturbances, remaining forest matrix, and residual structures (e.g. roots, sprouts, and in-stream wood) observed in the area. Our results suggest a recovery by 12 to 20 years for riparian forests of this region. However, areas degraded by intensive land-use apparently showed delayed recovery. We conclude that seizing resilience windows (defined here as the period when ecosystems retain high potential resilience) is essential to foster passive recovery of riparian forests and streams more cost-effectively in the tropics.

The emerald green tetra: a new restricted-range Hyphessobrycon (Characiformes: Characidae) from the upper rio Juruena, Chapada dos Parecis, Brazil

ABSTRACT A new species of Hyphessobrycon is described from the rio Mutum, a tributary of the rio Juruena, rio Tapajós basin, Brazil. The new taxon can be distinguished from its congeners by the presence of a well-defined and relatively narrow dark midlateral stripe on body, extending from head to the middle caudal-fin rays, presence of a humeral blotch, distal profile of the anal fin falcate in males, 13-16 branched anal-fin rays (vs. 17-26), and 11 or 12 horizontal scale rows around caudal peduncle. The new species shows polymorphism regarding the presence of the adipose fin, and a discussion on this type of polymorphism across the family and its systematic implications is presented.

The Impact of Roads on the Redistribution of Plants and Associated Arthropods in a Hyper-Arid Ecosystem

The construction of vehicular roads likely affects the distribution of natural resources. Although the effects of roads on different ecosystem aspects have been extensively studied, studies in arid and, particularly, in hyper-arid ecosystems are scarce. In drylands, where water is the main limiting factor, the effect of roads on the redistribution of water may have strong subsequent effects on the ecosystem, especially when roads cross natural water flow paths. To fill this knowledge gap, we studied the effects of a road that runs across a slope on the distribution of plants and animals in a hyper-arid environment. Changes in shrub cover, below and above the road, were quantified by remote sensing and image classification, while plant-associated arthropods were vacuum-sampled from shrub canopies and from open (inter-shrub) areas. We found that the spatial distribution of shrubs, a vital resource facilitating many other organisms, was affected by the road, with an increase in the shrub cover immediately above the road and a decrease below it. Arthropod abundance generally followed shrub cover, but the exact pattern depended on the specific group sampled. While some arthropod groups (e.g., aphids, parasitic wasps and barklice) thrived under the disturbed conditions above the road, other arthropod groups (e.g., mites and true bugs) were less abundant in the disturbed patches. Our results highlight the strong effects of human-made structures on the distribution of flora and fauna in arid ecosystems.

Human impacts and the loss of Neotropical freshwater fish diversity

Abstract Neotropical Ichthyology promotes the Special Issue (SI) “Human impacts and the loss of Neotropical freshwater fish diversity” with the purpose of publishing relevant scientific articles on the current biodiversity crisis and the loss of Neotropical freshwater fishes in the Anthropocene. The SI is composed of 22 publications, being two review articles and 20 original articles. A total of 107 researchers contributed to these papers, involving 44 institutions based in Brazil and six other countries. Published articles investigated main anthropic activities and their impacts on fish diversity, with special focus on river regulation, mining, land use changes, aquaculture, and fisheries. Studies provided evidence about the loss of fish diversity in the Neotropics, including fish kill events, demographic changes, contamination, changes in assemblage structure, loss of taxonomic and functional diversity, besides the degradation of ecosystem functions and services, and the lack of effective protection and conservation. Studies were conducted in rivers, streams, lakes, and reservoirs from different Neotropical systems. The studies published in this SI represent a relevant sample of the current worrisome situation of freshwater fishes in the Neotropical region and call for urgent revision in environmental policies, management and conservation initiatives, and socioeconomic priorities.

Negative impacts of mining on Neotropical freshwater fishes

Abstract Mining activities have significantly affected the Neotropical freshwater ichthyofauna, the most diverse in the world. However, no study has systematized knowledge on the subject. In this review, we assembled information on the main impacts of mining of crude oil, gold, iron, copper, and bauxite on aquatic ecosystems, emphasizing Neotropical freshwater fishes. The information obtained shows that mining activities generate several different disturbances, mainly via input of crude oil, metals and other pollutants, erosion and siltation, deforestation, and road construction. Mining has resulted in direct and indirect losses of fish diversity in several Neotropical waterbodies. The negative impacts on the ichthyofauna may change the structure of communities, compromise entire food chains, and erode ecosystem services provided by freshwater fishes. Particularly noteworthy is that mining activities (legal and illegal) are widespread in the Neotropics, and often located within or near protected areas. Actions to prevent and mitigate impacts, such as inspection, monitoring, management, and restoration plans, have been cursory or absent. In addition, there is strong political pressure to expand mining; if – or when – this happens, it will increase the potential of the activity to further diminish the diversity of Neotropical freshwater fishes.