Cecília Gontijo Leal

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.

Deep barcode divergence in Brazilian freshwater fishes: the case of the São Francisco River basin

Background and aims. The application of DNA barcoding as a global standard for fish identification is probing diverse worldwide realms (Nearctic, Australian and the Neotropics) and environments (e.g. marine and freshwater). Comparing the patterns of sequence divergence among conspecific and congeneric taxa between realms can provide valuable information on recent evolutionary histories of lineages as barcode data accumulates. Materials and methods. Herein, we have analyzed over 100 species (around 50%) of the Neotropical fish fauna from the São Francisco River, in southeast Brazil. Our aims were to test the performance of DNA barcoding in this biodiversity-rich region, and to compare patterns of genetic divergence with previous studies. Results. The mean Kimura two-parameter distances within species, genera, families, orders, and classes were 0.5, 10.6, 21.0, 22.7, and 24.4%, respectively, with 100% of the species examined successfully differentiated by barcoding. With the exception of Astyanax bimaculatus lacustris, Piabina argentea, and Bryconamericus stramineus, all other species yield a single, cohesive cluster of barcode sequences. The average ‘nearest-neighbor distance’ was 11.12%, 21-fold higher than the mean within species distance of around 0.54%. In a few instances, deep lineage divergences among conspecifics (up to 10%) and congenerics (up to 22.9%) taxa were revealed. Conclusions. Reflecting possible cases of cryptic speciation and the deeper phylogeographic history of São Francisco fish fauna, with some higher clades extending back into the late Cretaceous and Cenozoic (90 mya), when much of the diversification of the Neotropical region apparently took place. In addition, barcodes also highlighted misidentifications and helped to document range extensions for known species.

Morphology and habitat use by fishes of the Rio das Velhas basin in southeastern Brazil

We analyzed the morphology and habitat use of 16 small-sized fish species that are abundant in the Rio das Velhas basin using 17 morphological attributes. Habitat use was characterized in terms of the species mean density considering three hydraulic factors: substrate, water depth and mean water velocity. The distribution of species within the morphological space demonstrated congruence between the morphological attributes of a species, and their occupation of vertical microhabitats. Based on this data, the species could be classified as benthic A, benthic B or nektonic zone-dwelling species. Benthic A and B species differed mainly in relation to their body shapes, which were fusiform or depressed, respectively. Generally, habitat selection by each species was related to certain hydraulic factors, water velocity in particular. Siluriformes generally had morphological or behavioral adaptations to live in fast flowing habitats, and they were found more frequently than Characiformes in microhabitats with greater water velocities. Benthic species were the most selective with respect to substrate type. Between congener species, the habitat use of Serrapinnus heterodon and Serrapinnus piaba greatly overlapped, but these species were separated in morphological space. In contrast, Characidium species were closely related in morphological space but had great habitat segregation. Fish requirements and habitat use are poorly understood but are important to species management and habitat restoration.

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.

Morphological diversity of fish along the rio das Velhas, Minas Gerais, Brazil

The rio das Velhas, located in central Minas Gerais State (Brazil), is a major tributary of the rio Sao Francisco. Despite seve ralanthropogenic pressures, this basin supports more than 115 fish species. The aim of this study was to compare the morphologicalspace occupied by fish assemblages in four regions (headwaters, upper, middle, and lower course) along the channel of the riodas Velhas. We try to answer the following question: Is there a change in the morphological organization of the fish along thelongitudinal gradient of the river? Individuals from 67 species, collected at several sites in the basin from 1999 to 2008, weremeasured for 11 morphological attributes related to swimming behavior and habitat use. Through the graphs, the first twodimensions of the PCA suggest that the morphological volume occupied by the headwaters region is smaller than the othersections, because of the low richness of the site. However, morphological hypervolumes of the four reaches analyzed byEuclidean distances were not statistically different. The results indicated that only the density of morphological types increa sesalong the rio das Velhas, and there is no difference between the headwaters and upper courses. Therefore, in order to usefunctional groups related to the morphology of the species as tools to take measures for the conservation and revitalization of therio das Velhas, it is necessary analyze the density of species within these groups, as well as their composition.O rio das Velhas, localizado na regiao central do estado de Minas Gerais (Brasil), e o mais extenso tributario do rio SaoFrancisco. Apesar dos inumeros impactos antropicos que sofre, sua bacia abriga uma rica ictiofauna, com mais de 115 especiesconhecidas. O objetivo deste estudo foi comparar o espaco morfologico ocupado pelas assembleias de peixes em quatroregioes (cabeceira, alto curso, medio curso e baixo curso) ao longo da calha do rio das Velhas. Procuramos responder aseguinte pergunta: ha uma mudanca na organizacao morfologica da comunidade de peixes ao longo do gradiente longitudinaldo rio? Individuos de 67 especies, coletados em diversos trechos da bacia entre 1999 e 2008, foram medidos considerando 11atributos morfologicos relacionados ao comportamento natatorio e uso do habitat. Graficamente, as duas primeiras dimensoesda PCA sugerem que o volume morfologico ocupado pela regiao de cabeceira e menor do que o dos demais trechos, devido abaixa riqueza do local. Entretanto, os hipervolumes morfologicos dos quatro trechos analisados por meio das distanciaseuclidianas nao diferiram estatisticamente. Os resultados indicaram que apenas a densidade de tipos morfologicos aumentaao longo do rio das Velhas, sendo que nao ha diferenca entre a cabeceira e o alto curso. Portanto, para o uso de gruposfuncionais relacionados a morfologia das especies como ferramentas para tomada de medidas que visem a conservacao erevitalizacao do rio das Velhas, e necessaria a abordagem da densidade de especies dentro destes grupos, assim como suacomposicao.

Morphological Space Stability in Rivers under Different Disturbance Regimes

Morphological characteristics of fish communities were compared in four rivers with different levels of anthropogenic disturbance: Cipó, Curimataí, Pardo Grande, and Velhas. Discriminant function analysis indicated no morphological differences among the communities, suggesting a general morphological pattern for different river communities, regardless of their disturbance level. However, this pattern was shaped by different taxa in each river. Because of the poorer condition of the Velhas River (substrate type, riparian vegetation, and anthropogenic disturbance), it seems that species morphological range is influencing the common morphological pattern. Even with notable differences in biological condition, the Velhas River still accommodates the same range of morphological types, but not the same species pool found in well-preserved rivers within the basin. For this reason, the maintenance of tributaries, with their particular fish species and different physical habitat characteristics, is essential for the conservation of the ichthyofauna on a basin scale. Moreover, the analysis of morphology and composition together allowed a more critical approach of disturbance effects and suggested that these community aspects respond differently.