Jansen Zuanon

Brazil's environmental leadership at risk

Mining and dams threaten protected areas Over the past two decades, Brazil has emerged as an environmental leader, playing a prominent role in international fora such as the United Nations (UN) Conferences on Sustainable Development. The country has earned praise for the expansion of its protected area (PA) network and reductions in Amazon deforestation. Yet these successes are being compromised by development pressures and shifts in legislation. We highlight concerns for the newly elected government regarding development of major infrastructure and natural resource extraction projects in PAs and indigenous lands (ILs).

Relationships between Habitat Characteristics and Fish Assemblages in Small Streams of Central Amazonia

Abstract Small streams with acidic, nutrient-poor waters form a dense hydrological system in Central Amazonia. However, little is known about the fish assemblages that occur in these systems. We investigated the relationships among stream size, substrate, and other physical-chemical factors and fish distributions. Fish assemblages and stream characteristics were sampled in 50-m long sections of streams at 38 sites distributed throughout the 100-km2 florestal reserve. Forty-nine species were encountered. The mean richness was similar among sites; however, community composition was correlated with physical and chemical characteristics of the streams. The mean number of species per site (X̄ = 9) was low in relation to the total number of species recorded from the reserve (49) and in relation to the ichthyofauna that has been recorded from small forest streams near the study area. This contrasts with studies in temperate zones where strong patterns of species addition along the river continuum were found, resulting in prominent species richness gradients. The high between-site turnover in species composition and the strong habitat specificity indicate that it will be necessary to create a network of reserves to efficiently conserve the fish fauna of small forest streams in Central Amazonia. Na Amazônia Central, pequenos riachos de águas ácidas e pobres em nutrientes constituem uma densa rede hidrica. Contudo, pouco é conhecido sobre a riqueza e abundância de sua ictiofauna. Para determinar a composição ictiofaunistica existente, bem como determinar a relação entre o tamanho dos igarapés, substratos presentes nos leitos, e fatores fisico-quimicos e a estrutura da comunidade, nós amostramos trechos de 50-m em 38 locais distribuidos em uma reserva de 100-km2. A riqueza média foi semelhante entre os sitios de amostragem. No entanto, a composição de espécies foi relacionada com caracteristicas fisicas e quimicas dos riachos. O número médio de espécies por local (X̄ = 9) foi pequeno em relação ao número total de espécies encontrado na reserva (49) e em relação à ictiofauna que foi encontrada em pequenos riachos próximos à área de estudo. Isto contrasta com estudos realizados em zonas temperadas, onde um padrão muito forte de adição de espécies ao longo das bacias foi encontrado, resultando em um gradiente acentuado de riqueza de espécies. A alta troca na composição de espécies entre locais, e a alta especificidade de hábitat, indica que seria necessário criar uma rede de reservas para conservar eficientemente a ictiofauna de pequenos riachos na região.

A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network

Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.

Hydropower and the future of Amazonian biodiversity

In an effort to ensure energy independence and exploit mineral resources, the governments of Amazonian countries are embarking on a major dam building drive on the basin’s rivers, with 191 dams finished and a further 246 planned or under construction. This rush to harvest the basin’s vast renewable energy capacity has come without proper consideration of the likely negative environmental externalities on the world’s most speciose freshwater and terrestrial biotas. Here we highlight the economic drivers for hydropower development and review the literature to summarise the impacts of dam building on Amazonian biodiversity. We identify both direct and indirect impacts through the anticipated loss, fragmentation and degradation of riparian habitats. We then propose a series of measures to assess, curb and mitigate the impacts of destructive dams on Amazonian biodiversity.

Is environmental legislation conserving tropical stream faunas? A large‐scale assessment of local, riparian and catchment‐scale influences on Amazonian fish

Agricultural expansion and intensification are major threats to tropical biodiversity. In addition to the direct removal of native vegetation, agricultural expansion often elicits other human-induced disturbances, many of which are poorly addressed by existing environmental legislation and conservation programmes. This is particularly true for tropical freshwater systems, where there is considerable uncertainty about whether a legislative focus on protecting riparian vegetation is sufficient to conserve stream fauna.To assess the extent to which stream fish are being effectively conserved in agricultural landscapes, we examined the spatial distribution of assemblages in river basins to identify the relative importance of human impacts at instream, riparian and catchment scales, in shaping observed patterns. We used an extensive dataset on the ecological condition of 83 low-order streams distributed in three river basins in the eastern Brazilian Amazon.We collected and identified 24,420 individual fish from 134 species. Multiplicative diversity partitioning revealed high levels of compositional dissimilarity (DS) among stream sites (DS = 0.74 to 0.83) and river basins (DS = 0.82), due mainly to turnover (77.8% to 81.8%) rather than nestedness. The highly heterogeneous fish faunas in small Amazonian streams underscore the vital importance of enacting measures to protect forests on private lands outside of public protected areas.Instream habitat features explained more variability in fish assemblages (15%-19%) than riparian (2%-12%), catchment (4%-13%) or natural covariates (4%-11%). Although grouping species into functional guilds allowed us to explain up to 31% of their abundance (i.e. for nektonic herbivores), individual riparian - and catchment - scale predictor variables that are commonly a focus of environmental legislation explained very little of the observed variation (partial R2 values mostly <5%).Policy implications. Current rates of agricultural intensification and mechanization in tropical landscapes are unprecedented, yet the existing legislative frameworks focusing on protecting riparian vegetation seem insufficient to conserve stream environments and their fish assemblages. To safeguard the species-rich freshwater biota of small Amazonian streams, conservation actions must shift towards managing whole basins and drainage networks, as well as agricultural practices in already-cleared land.

Galling Insects (Diptera: Cecidomyiidae) Survive Inundation during Host Plant Flooding in Central Amazonia

The effect of host plant inundation on survivorship of Symmeria paniculata’s galling herbivores was investigated in Central Amazonian floodplain forest. The majority of submerged galls were alive (62% of morphospecies 1 and 70% of morphospecies 2). Survivorship was similar between submerged leaves and new leaves that were never submerged. Some submerged galls were eaten by fish. To the best of our knowledge, this is the first report of galling insect survivorship under severe flooding.

Remarkable Geographic Structuring of Rheophilic Fishes of the Lower Araguaia River

Rapids and waterfalls, and their associated fauna and flora are in peril. With the construction of each new hydroelectric dam, more rapids and waterfalls are destroyed, leading to the disappearance of associated fauna and flora. Areas of rapids harbor distinct, highly endemic rheophilic fauna and flora adapted to an extreme environment. Rheophilic habitats also have disjunct distribution both within and across rivers. Rheophilic habitats thus represent islands of suitable habitat separated by stretches of unsuitable habitat. In this study, we investigated to what extent, if any, species of cichlid and anostomid fishes associated with rheophilic habitats were structured among the rapids of Araguaia River in the Brazilian Amazon. We tested both for population structuring as well as non-random distribution of lineages among rapids. Eight of the nine species had multiple lineages, five of these nine species were structured, and three of the eight species with multiple lineages showed non-random distribution of lineages among rapids. These results demonstrate that in addition to high levels of endemicism of rheophilic fishes, different rapids even within the same river are occupied by different lineages. Rheophilic species and communities occupying different rapids are, therefore, not interchangeable, and this realization must be taken into account when proposing mitigatory/compensatory measures in hydroelectric projects, and in conservation planning.

Environment and Development. Brazil's environmental leadership at risk.

Mining and dams threaten protected areas Over the past two decades, Brazil has emerged as an environmental leader, playing a prominent role in international fora such as the United Nations (UN) Conferences on Sustainable Development. The country has earned praise for the expansion of its protected area (PA) network and reductions in Amazon deforestation. Yet these successes are being compromised by development pressures and shifts in legislation. We highlight concerns for the newly elected government regarding development of major infrastructure and natural resource extraction projects in PAs and indigenous lands (ILs).

Testing Wallace's intuition: water type, reproductive isolation and divergence in an Amazonian fish

Alfred Russel Wallace proposed classifying Amazon rivers based on their colour and clarity: white, black and clear water. Wallace also proposed that black waters could mediate diversification and yield distinct fish species. Here, we bring evidence of speciation mediated by water type in the sailfin tetra (Crenuchus spilurus), a fish whose range encompasses rivers of very distinct hydrochemical conditions. Distribution of the two main lineages concords with Wallaces water types: one restricted to the acidic and nutrient‐poor waters of the Negro River (herein Rio Negro lineage) and a second widespread throughout the remaining of the species’ distribution (herein Amazonas lineage). These lineages occur over a very broad geographical range, suggesting that despite occurring in regions separated by thousands of kilometres, individuals of the distinct lineages fail to occupy each others habitats, hundreds of metres apart and not separated by physical barrier. Reproductive isolation was assessed in isolated pairs exposed to black‐water conditions. All pairs with at least one individual of the lineage not native to black waters showed significantly lower spawning success, suggesting that the water type affected the fitness and contributed to reproductive isolation. Our results endorse Wallaces intuition and highlight the importance of ecological factors in shaping diversity of the Amazon fish fauna.