Fruits and frugivory in neotropical primates and in Amazonian flooded and unflooded forests

The richness and resilience of tropical forest ecosystems are best described by the myriad of ecological interactions linking co-occurring species together. The many functions previously served by ecological links are often only detected once these links are lost. Of particular interest in this regard are the mutualistic networks between fruiting plants and vertebrate frugivores, whose interdependent relationship is fundamental to the functioning of tropical forests. This thesis examined these fruitfrugivore interactions at two contrasting scales, and using two different approaches. On a landscape scale in western Brazilian Amazonia, the focus was on a community-wide assessment, with particular attention paid to the differences between two highly divergent but adjacent species-rich forest types, seasonally-flooded várzea forests and unflooded terra firme forests. As part of this comparison, the powerful role of the annual flood pulse was shown to determine both spatial patterns of forest structure and temporal patterns of fruit production. The strong influence of this seasonal cycle was apparent in the adaptive traits observed in plants and animals, with corresponding effects upon their networks of interactions. The role of frugivore body size as an important trait in relation to the degree of frugivory within consumers was emphasised via one of the most extensive compilations on the feeding ecology of any frugivorous vertebrate taxon. By amassing the observations of feeding records accumulated over several decades of neotropical primate field research, and accounting for the highly variable levels of sampling effort among primate species, the prevalence of frugivory at the mid-high spectrum of body mass was confirmed. This continental-scale metaanalysis also revealed that, despite representing arguably the most observable and wellstudied group of vertebrate frugivores in tropical forests worldwide, most primate species were heavily undersampled in terms of the richness of fruits known to occur in their diets. These astounding gaps in our cumulative knowledge highlight the challenges faced in assembling comprehensive fruit-frugivore networks for entire communities, where the diets of most consumers are even more poorly understood than for primates. This is particularly pertinent in the face of ever-increasing threats to ecosystems comprised of, and sustained by, these complex webs of interactions

Multitrophic diversity effects of network degradation

Predicting the functional consequences of biodiversity loss in realistic, multitrophic communities remains a challenge. No existing biodiversity-ecosystem function study to date has simultaneously incorporated information on species traits, network topology, and extinction across multiple trophic levels, while all three factors are independently understood as critical drivers of post-extinction network structure and function. We fill this gap by comparing the functional consequences of simulated species loss both within (monotrophic) and across (bitrophic) trophic levels, in an ecological interaction network estimated from spatially explicit field data on tropical fecal detritus producer and consumers (mammals and dung beetles). We simulated trait-ordered beetle and mammal extinction separately (monotrophic extinction) and the coextinction of beetles following mammal loss (bitrophic extinction), according to network structure. We also compared the diversity effects of bitrophic extinction models using a standard monotrophic function (the daily production or consumption of fecal detritus) and a unique bitrophic functional metric (the proportion of daily detritus production that is consumed). We found similar mono- and bitrophic diversity effects, regardless of which species traits were used to drive extinctions, yet divergent predictions when different measures of function were used. The inclusion of information on network structure had little apparent effect on the qualitative relationship between diversity and function. These results contribute to our growing understanding of the functional consequences of biodiversity from real systems and underscore the importance of species traits and realistic functional metrics to assessments of the ecosystem impacts of network degradation through species loss

Population recovery, seasonal site fidelity and daily activity of pirarucu (Arapaima spp.) in an Amazonian floodplain mosaic

1. Pirarucu (Arapaima spp.) are the world's largest scaled freshwater fish, reaching 3 m in length and >200 kg in weight. Historical overfishing has devastated populations of this remarkable fish across Amazonian floodplains, but community‐based management programmes are now stimulating the recovery of wild populations. 2. Pirarucu have evolved a unique set of life history traits, some of which have important implications for population management. Individuals exhibit lateral annual migration patterns during the prolonged annual flood pulse, entering flooded forests to reproduce and forage. During this period, although managed fish stocks become less monopolisable by local communities responsible for managing protected lakes, pirarucu can occupy and reproduce in new environments and thus potentially contribute to population recovery. 3. Here, we show a strong pattern of pirarucu (Arapaima cf. gigas) population recovery under community‐based management in an area along the Juruá River, in western Brazilian Amazonia. We show evidence of population recovery even outside formal protected areas, reinforcing the suitability of pirarucu community‐based management as a powerful tool for both biodiversity conservation and the improvement of local livelihoods. We also show pirarucu movements across a floodplain mosaic—including lakes, the main river channel, tributary streams, and flooded forests—during the wet season. 4. Our results support evidence of site fidelity among migrating pirarucu, justifying the high effort invested by local communities in seasonally protecting lakes from poachers and illegal fishers. Finally, restricted daily movement patterns by pirarucu support the suitability of population estimates based on day‐time counts because the chance of double counting is substantially reduced during the day when these counts are conducted. We highlight the strong suitability of this species for community‐based management, since they can: (1) replenish new environments during the wet season through migration and possibly also reproduction; and (2) be efficiently harvested during the dry season, delivering social and ecological benefits at large spatial scales. 5. Positive examples of fisheries management, which align biodiversity conservation and social development, are important for building optimism, and influencing local and international stakeholders. Our study shows how engaging and empowering local communities to help monitor the movement ecology of target species can be an effective strategy to support the sustainable management of aquatic resources in tropical environments

Effect of protection status on mammal richness and abundance in Afromontane forests of the Udzungwa Mountains, Tanzania

The effectiveness of Protected Areas (PAs) in reducing hunting pressure on mammal populations in tropical forests has rarely been examined at a community-wide level. In African forests, commercial and subsistence hunting are widespread, but assessments of mammal abundance and distribution patterns are often lacking. We investigated patterns of occupancy and abundance for 27 species of medium- to large-bodied mammals (>2 kg) within Tanzania's Udzungwa Mountains Afromontane forests, a global biodiversity hotspot. We sampled 22 forest sites within 10 forests under varying degrees of protection, elevation, distance to extractive communities, and levels of law enforcement. We sampled 251.7 km of recce line transects during dry seasons (July–November) between September 2007 and July 2010. We found a strong positive effect of protection status on species richness and on encounter rates of the most commonly encountered species. Consistent with the levels of resources and enforcement within each PA category, there was a significant progression in species richness and abundance from Forest Reserves through Nature Reserves to sites within Udzungwa Mountains National Park. Protective status closely reflected levels of disturbance. Snaring activity, and distance to ranger posts were identified as significant predictors of overall species richness and encounter rates for mammal species, including endemics. The species-area relationship for our study species was found to be largely overridden by levels of protection. Our findings demonstrate PA effectiveness in Afromontane forests and reinforce concerns over hunting pressures particularly the threat posed by snares

Unintended multispecies co-benefits of an Amazonian community-based conservation programme

Urgent challenges posed by widespread degradation in tropical ecosystems with poor governance require new development pathways to reconcile biodiversity conservation and human welfare. Community-based conservation management has shown potential for integrating socio-economic needs with conservation goals in tropical environments; however, assessing the effectiveness of this approach is often held back by the lack of comprehensive ecological assessments. We conduct a robust ecological evaluation of the largest community-based conservation management initiative in the Brazilian Amazon over the last 40 years. We show that this programme has induced large-scale population recovery of the target giant South American turtle (Podocnemis expansa) and other freshwater turtles along a 1,500-km section of a major tributary of the Amazon River. Poaching activity on protected beaches was around 2% compared to 99% on unprotected beaches. We also find positive demographic co-benefits across a wide range of non-target vertebrate and invertebrate taxa. As a result, beaches protected by local communities represent islands of high biodiversity, while unprotected beaches remain ‘empty and silent’, showing the effectiveness of empowering local conservation action, particularly in countries experiencing shortages in financial and human resources

Coarse- and fine-scale patterns of distribution and habitat selection places an Amazonian floodplain curassow in double jeopardy

Patterns of habitat selection are influenced by local productivity, resource availability and predation risk. Species have taken millions of years to hone the macro- and micro-habitats they occupy, but these may now overlap with contemporary human threats within natural species ranges. Wattled Curassow (Crax globulosa), an endemic galliform species of the western Amazon, is threatened by both hunting and habitat loss, and is restricted to whitewater floodplain forests of major Amazonian rivers. In this study conducted along the Juruá River, Amazonas, Brazil, we quantified the ranging ecology and fine-scale patterns of habitat selection of the species. We estimated the home range size of C. globulosa using conventional VHF telemetry. To estimate patterns of habitat selection, we used geolocations of day ranges to examine the extent and intensity of use across the floodplain, which were then compared to a high-resolution flood-map of the study area. We captured two females and one male, which were monitored for 13 months between September 2014 and September 2015. Average home range size was 283 ha, based on the 95% aLoCoH estimator. Wattled Curassows selected areas of prolonged flood-pulses (6-8 months/year) and had a consistent tendency to be near open water, usually in close proximity to river banks and lakes, especially during the dry season. Amazonian floodplains are densely settled, and the small portions of floodplain habitat used by Wattled Curassows are both the most accessible to hunters and most vulnerable to deforestation. As a result, the geographic and ecological distribution of Wattled Curassows places them at much higher extinction risk at multiple spatial scales, highlighting the need to consider habitat preferences within their conservation strategy

Zooming into plant-flower visitor networks: an individual trait-based approach

Understanding how ecological communities are structured is a major goal in ecology. Ecological networks representing interaction patterns among species have become a powerful tool to capture the mechanisms underlying plant-animal assemblages. However, these networks largely do not account for inter-individual variability and thus may be limiting our development of a clear mechanistic understanding of community structure. In this study, we develop a new individual-trait based approach to examine the importance of individual plant and pollinator functional size traits (pollinator thorax width and plant nectar holder depth) in mutualistic networks. We performed hierarchical cluster analyses to group interacting individuals into classes, according to their similarity in functional size. We then compared the structure of bee-flower networks where nodes represented either species identity or trait sets. The individual trait-based network was almost twice as nested as its species-based equivalent and it had a more symmetric linkage pattern resulting from of a high degree of size-matching. In conclusion, we show that by constructing individual trait-based networks we can reveal important patterns otherwise difficult to observe in species-based networks and thus improve our understanding of community structure. We therefore recommend using both trait-based and species-based approaches together to develop a clearer understanding of the properties of ecological networks

Structure and Composition of Terra Firme and Seasonally Flooded Várzea Forests in the Western Brazilian Amazon

Research Highlights: Rare, or sparsely distributed, species drive the floristic diversity of upland, terra firme and seasonally flooded forests in the central Juruá—a remote and hitherto floristically poorly known area in the Brazilian Amazon. Background and Objectives: Floristic inventories are critical for modelling and understanding the role of Amazonian forests in climate regulation, for sustainable management of forest resources and efficient conservation planning. Yet, detailed information about the often complex spatial distributions of many Amazonian woody plants is limited. Here, we provide information about forest structure and species composition from a remote terra firme forest and an adjacent floodplain forest in the western Brazilian Amazon. More specifically, we ask (1) how floristically different are the terra firme and floodplain forests? and (2) how variable is species composition within the same forest type? Materials and Methods: Between September 2016 and October 2017, we inventoried 97 plots (each 0.1 ha; 100 × 10 m) placed at least 800 m apart, with 46 plots in terra firme forest and 51 in seasonally flooded forest. We included all trees, hemi-epiphytes and palms with diameter at breast height (dbh) > 10 cm and woody lianas > 5 cm dbh. We examine forest structure, family- and species-level floristic composition and species diversity within and between forest types using family and species importance values, rarefaction curves and dissimilarity matrices. Results: Terra firme forest and seasonally flooded forest woody plant communities differ both in structure and species composition, which was highly variable within forest types. Many species were shared between terra firme and seasonally flooded forests, but most species were forest type-specific. Whereas species richness was greatest in the terra firme forest, floodplain species richness was among the highest regionally. Conclusions: Floodplain forests are a crucial complement to terra firme forests in terms of Amazonian woody plant diversity

Human-wildlife conflicts with crocodilians, cetaceans and otters in the tropics and subtropics

Conservation of freshwater biodiversity and management of human-wildlife conflicts are major conservation challenges globally. Human-wildlife conflict occurs due to attacks on people, depredation of fisheries, damage to fishing equipment and entanglement in nets. Here we review the current literature on conflicts with tropical and subtropical crocodilians, cetaceans and otters in freshwater and brackish habitats. We also present a new multispecies case study of conflicts with four freshwater predators in the Western Amazon: black caiman (Melanosuchus niger), giant otter (Pteronura brasiliensis), boto (Inia geoffrensis) and tucuxi (Sotalia fluviatilis). Documented conflicts occur with 34 crocodilian, cetacean and otter species. Of the species reviewed in this study, 37.5% had conflicts frequently documented in the literature, with the saltwater crocodile (Crocodylus porosus) the most studied species. We found conflict severity had a positive relationship with species body mass, and a negative relationship with IUCN Red List status. In the Amazonian case study, we found that the black caiman was ranked as the greatest ‘problem’ followed by the boto, giant otter and tucuxi. There was a significant difference between the responses of local fishers when each of the four species were found entangled in nets. We make recommendations for future research, based on the findings of the review and Amazon case study, including the need to standardise data collection

Human-wildlife conflicts with crocodilians, cetaceans and otters in the tropics and subtropics

Conservation of freshwater biodiversity and management of human-wildlife conflicts are major conservation challenges globally. Human-wildlife conflict occurs due to attacks on people, depredation of fisheries, damage to fishing equipment and entanglement in nets. Here we review the current literature on conflicts with tropical and subtropical crocodilians, cetaceans and otters in freshwater and brackish habitats. We also present a new multispecies case study of conflicts with four freshwater predators in the Western Amazon: black caiman (Melanosuchus niger), giant otter (Pteronura brasiliensis), boto (Inia geoffrensis) and tucuxi (Sotalia fluviatilis). Documented conflicts occur with 34 crocodilian, cetacean and otter species. Of the species reviewed in this study, 37.5% had conflicts frequently documented in the literature, with the saltwater crocodile (Crocodylus porosus) the most studied species. We found conflict severity had a positive relationship with species body mass, and a negative relationship with IUCN Red List status. In the Amazonian case study, we found that the black caiman was ranked as the greatest ‘problem’ followed by the boto, giant otter and tucuxi. There was a significant difference between the responses of local fishers when each of the four species were found entangled in nets. We make recommendations for future research, based on the findings of the review and Amazon case study, including the need to standardise data collection