Central Brazilian Amazon Research Articles

FEEDING ECOLOGY OF <i>Cichlasoma amazonarum </i> (Teleostei, Cichlidae) IN THE CENTRAL AMAZON LAKES, BRAZIL.

The diet of the cichlid Cichlasoma amazonarum was investigated through an analysis of 270 gastric contents obtained from monthly samples collected from five lakes located in the Central Brazilian Amazon, throughout the year of 2012. The composition of the diet was assessed using the methods of frequency of occurrence and relative dominance (frequency of biomass), which were combined in the Alimentary Importance Index (AIi) in accordance with the hydrological cycle’s extreme periods of drought and high waters. The intestinal coefficient was investigated to demonstrate the feeding tendencies of the species. The breadth and diversity of the trophic niche were also compared for these periods. The intestinal coefficient for the species (0.95), combined with the results of the analysis of food content, showed a species that demonstrates carnivorous/insectivorous habits. During the high water season, the diet is composed of unidentified animal matter, unidentified larvae and insects; and in the drought season, plant matter, unidentified animal matter and insects. Although there was no significant difference in dietary diversity between seasonal extremes, the analysis of the breadth of the trophic niche characterises the species as feeding specialists.

Activity of the insectivorous batPteronotus parnelliirelative to insect resources and vegetation structure

Riparian areas often are assumed to be necessary sites for foraging by insectivorous bats because of high insect availability and ease of movement and echolocation in the forest. However, effects of vegetation clutter and insect availability on bat activity have not been compared between riparian and nonriparian areas. We used autonomous recorders to evaluate the effects of vegetation structure, insect mass, and assemblage composition on the activity of the aerial insectivorous bat Pteronotus parnellii along stream channels and nonriparian areas in a tropical rainforest in central Brazilian Amazonia. We quantified vegetation clutter using horizontal photographs, captured nocturnal insects with light traps, and recorded bat activity for 110 nights (1,320 h) in 22 sampling plots. Pteronotus parnellii was more active in sites with dense understory vegetation, which were more common away from riparian zones. Bat activity was related to insect availability (mass and composition), independent of the habitat typ...

Reproductive aspects of the flag cichlid Mesonauta insignis in várzea lakes of the Central Brazilian Amazon

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 24:35-40 (2015) - DOI: https://doi.org/10.3354/ab00631 NOTE Reproductive aspects of the flag cichlid Mesonauta insignis in várzea lakes of the Central Brazilian Amazon Tânia Cristiane Gonçalves da Silva1,*, Daíza Lima1, Ana Carolina Prado-Valladares1, Maria Auxiliadora Pantoja Ferreira2, Rossineide Martins da Rocha2, Helder Lima de Queiroz1 1Mamirauá Institute for Sustainable Development, MISD, 69470-000 Amazonas, Brazil 2Federal University of Pará, (UFPA), 66075-110 Pará, Brazil *Corresponding author: tania@mamiraua.org.br ABSTRACT: We describe the most important reproductive aspects of the flag cichlid Mesonauta insignis in the floodplain (várzea) lakes of the Central Brazilian Amazon. Between September 2005 and August 2006, fish were collected monthly from mattresses of aquatic macrophytes. Biometric measurements as well as macroscopic and microscopic analyses of the gonads were performed. Standard body lengths ranged from 2.4 to 9.3 cm, and weight-length relationships were indicative of isometric growth patterns. Reproduction events were detected in all months, but the gonadosomatic index indicated a reproductive season from October to February (during low and rising water periods), reaching a reproductive peak in February. Average fecundity was 1184 ± 40.82 (mean ± SD) mature oocytes. M. insignis exhibits an asynchronous oocytal development, characteristic of multiple spawnings. Morphological and histological analyses indicated 5 gonadal maturation stages for females. Average standard length at first sexual maturation was 5.18 cm for females and 5.5 cm for males. M. insignis shows late sexual maturation. Taken together, these aspects suggest that a life history strategy of ‘equilibrium’ predominates in the species; consequently, M. insignis can be considered vulnerable to high extraction rates, and can only be exploited sustainably if adequate precautionary management procedures are adopted. Some management measures are suggested for the exploitation of this species in the Central Amazon. KEY WORDS: Fecundity · Gonad histology · Management · Life history strategies · Sexual maturation · Spawning Full text in pdf format PreviousNextCite this article as: Silva TCG, Lima D, Prado-Valladares AC, Ferreira MAP, Rocha RM, Queiroz HL (2015) Reproductive aspects of the flag cichlid Mesonauta insignis in várzea lakes of the Central Brazilian Amazon. Aquat Biol 24:35-40. https://doi.org/10.3354/ab00631 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 24, No. 1. Online publication date: June 09, 2015 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2015 Inter-Research.

Short Note: Sleeping Sites Used by Giant Otters (Pteronura brasiliensis) in the Balbina Hydroelectric Reservoir, Central Brazilian Amazon

Short Note: Sleeping Sites Used by Giant Otters (Pteronura brasiliensis) in the Balbina Hydroelectric Reservoir, Central Brazilian Amazon

Ecological applications of differences in the hydraulic efficiency of palms and broad-leaved trees

In tropical forests, co-occurring woody monocot and dicot species adapted different water use strategies highly depending on their investment in the hydraulic conduit properties. We studied the hydraulic efficiency of palms and broad-leaved tropical tree species from a moist tropical lowland forest in the Central Brazilian Amazon. Therefore, we harvested 34 trees and 10 acai palms and measured vessel size and frequency at diameter at breast height and additionally at the base of the crown shaft for the palms. Further, we assessed the active xylem area to estimate the hydraulic conductivity through Hagen Poiseuille’s adapted theoretical equation. Mean vessel diameter in dicot trees was 127.62 ± 49.22 μm with an average 9.09 ± 6.50 vessels per mm2. Mean conduits sizes at the base (h = 0.10 m) of palm trees were larger with 288.20 ± 32.96 μm and less frequent with 1.40 ± 0.46 vessels per mm2. Hydraulic conductivity was on average 3.31 ± 4.59 kg m−1 s−1 MPa−1 for dicot trees. Mean hydraulic conductivity in acai palms was 20.45 ± 10.6 kg m−1 s−1 MPa−1 at the base, and increased to 124.73 ± 55.2 kg m−1 s−1 MPa−1 at the crown base. Hydraulic conductivity at the base of the crown was higher than in the base of the trunk due to the high density of vessels in a small cross-section in this height. Furthermore, we found a species-independent relationship between vessel diameter and frequency. We conclude that the differences found in the hydraulic efficiency give some evidence that palms have a lower occurrence of embolism and cavitation than trees, which is due to stiffer and stronger conduit pathways and efficient drought-avoiding strategies. The differences in hydraulic architecture between palms and trees imply different water use patterns thus varying niche differentiation, but this does not consequently need to be an excluding factor for coexistence in the same environment.

The floating forest: traditional knowledge and use of matupá vegetation islands by riverine peoples of the central Amazon.

Matupás are floating vegetation islands found in floodplain lakes of the central Brazilian Amazon. They form initially from the agglomeration of aquatic vegetation, and through time can accumulate a substrate of organic matter sufficient to grow forest patches of several hectares in area and up to 12 m in height. There is little published information on matupás despite their singular characteristics and importance to local fauna and people. In this study we document the traditional ecological knowledge of riverine populations who live near and interact with matupás. We expected that their knowledge, acquired through long term observations and use in different stages of the matupá life cycle, could help clarify various aspects about the ecology and natural history of these islands that field biologists may not have had the opportunity to observe. Research was carried out in five riverine communities of the Amanã Sustainable Development Reserve (Brazil). Semi-structured interviews were conducted with 45 inhabitants in order to register local understandings of how matupás are formed, biotic/abiotic factors related to their occurrence, the plants and animals that occur on them, their ecological relevance, and local uses. Local people elucidated several little-known aspects about matupá ecology, especially regarding the importance of seasonal dynamics of high/low water for matupás formation and the relevance of these islands for fish populations. Soil from matupás is especially fertile and is frequently gathered for use in vegetable gardens. In some cases, crops are planted directly onto matupás, representing an incipient agricultural experiment that was previously undocumented in the Amazon. Matupás are also considered a strategic habitat for fishing, mainly for arapaima (Arapaima gigas). The systematic study of traditional ecological knowledge proved to be an important tool for understanding this little-known Amazonian landscape.

Household Agrobiodiversity Management on Amazonian Dark Earths, Oxisols, and Floodplain Soils on the Lower Madeira River, Brazil

Smallholder farmers play a critical role in the maintenance of global agrobiodiversity. However, the social and environmental factors that shape agrobiodiversity and its management in rural smallholder communities are still debated among scholars. This study examines variation in the diversity of useful plant species (i.e., species richness) managed by households located in three distinct environments along the Lower Madeira River in the Central Brazilian Amazon: Amazonian Dark Earths (ADE), upland Oxisols (OX), and floodplain soils (FP). Among the 106 households studied, those located on ADE managed a significantly higher number of useful species than those on floodplain soils but not than those on Oxisols. A generalized linear mixed effects model indicates that the age of the household head, number of household members and adults, and area of land under cultivation are statistically significant factors that influence species richness across all households. Ethnographic data are employed to contextualize these findings and discuss other influences on agrobiodiversity management in rural Amazonian communities, including regional historical ecology and the life histories of individual farmers.

Edge‐mediated compositional and functional decay of tree assemblages in Amazonian forest islands after 26 years of isolation

Summary Islands formed upstream of mega hydroelectric dams are excellent experimental landscapes to assess the impacts of habitat fragmentation on biodiversity. We examined the effects of plot‐, patch‐ and landscape‐scale variables on the patterns of floristic diversity across 34 forest islands that had experienced 26 years of isolation since the creation of the 4437 km2 Balbina Hydroelectric Reservoir of central Brazilian Amazonia. In addition, three undisturbed continuous forest sites in neighbouring mainland areas were also sampled across a comparable elevational gradient. We identified all live trees ≥10 cm DBH at species level within a total of 87 quarter‐hectare forest plots and conducted a comprehensive compilation of functional attributes of each tree species. We then examined species‐area relationships (SARs) and the additional effects of patch and landscape‐scale metrics on patterns of tree assemblage heterogeneity, both in terms of taxonomic and functional diversity. Despite a clearly positive SAR, edge‐mediated forest disturbance was the single most important driver of species composition and abundance within islands. Our results suggest that non‐random floristic transitions within island plots followed a predictable pattern, with different life‐history traits either penalizing or rewarding local persistence of different functional groups. Distance to edges mediated the probability of tree mortality induced by windfalls and episodic surface fires, clearly resulting in faster species turnover and unidirectional changes in guild structure within small islands where light‐wooded fast‐growing pioneers largely replaced heavy‐wooded species of the old‐growth flora. Synthesis. Following a simultaneous 26‐year post‐isolation history, we disentangle the effects of habitat loss and insularization on tree assemblages within a large set of Amazonian ‘true’ forest islands, of variable sizes, sharing a uniform open‐water matrix. Area effects are expressed via a response to edge effects, with trees in smaller islands being more vulnerable to edge‐related surface fires and wind‐throws. Additionally, forest edge effects can be a powerful driver of non‐random floristic transitions across islands within the Balbina archipelago via a process of rapid pioneer proliferation, drastically affecting both the taxonomic and functional composition of insular tree communities. Finally, our results indicate that detrimental effects of forest fragmentation induced by hydroelectric dams are considerably stronger than those of forest patches embedded within a terrestrial vegetation matrix.

First record of jaguar predation on giant otter (Pteronura brasiliensis)

Top of the food chain predators are often not predated upon. However, even though the giant otter (Pteronura brasiliensis) is in that category, the literature mentions many species as potential predators, including the jaguar (Panthera onca). Notwithstanding up until now there has been no registered confirmation of jaguar predation on giant otters. A predation of a jaguar on an adult female giant otter was recorded for the first time during our radio-telemetry study on giant otters in Balbina hydroelectric reservoir in Central Brazilian Amazon. The female had had a transmitter implanted on February 2012 and was killed by a jaguar ninety-four days after the surgery. This giant otter was a solitary specimen, which was captured by a jaguar while asleep in a shelter under a fallen tree trunk on the banks of one of the reservoir’s islands. The solitary pattern found in such individuals combined with the frequent use of shelters, allows predators to access them more easily and may have contributed to the predation observed in this study.

Unexplored Amazonian diversity: rare and phylogenetically enigmatic tree species are newly collected

The Amazon is renowned to hold an unprecedented, yet poorly­known or unexplored plant diversity. This study aimed to report new collections on five rare or little­known and phylogenetically enigmatic trees, Aguiaria excelsa (Malvaceae, Bombacoideae), Hylocarpa heterocarpa (Humiriaceae), and the papilionoid legumes Monopteryx uaucu , Petaladenium urceoliferum , and Uleanthus erythrinoides , that became available after recent fieldwork in the western and central Brazilian Amazon region. All five genera, except for Monopteryx , are monospecific and represented in herbaria by only the type or at most few collections made more than 30 years ago. Comments on morphological affinities, never­seen­before photographs, and a distribution map of all species are given. A lectotype for U. erythrinoides is here designated. We also provide a complete taxonomic description for P. urceoliferum , whose pods until presently were unknown. Since these genera are missing branches in the molecular phylogenetic trees of Leguminosae, Humiriaceae, and Malvaceae, the opportunity to include them in future phylogenetic studies will certainly clarify the evolutionary history and taxonomy of their respective families.

Morphological and molecular identification of ticks infesting Boa constrictor (Squamata, Boidae) in Manaus (Central Brazilian Amazon).

The Boa constrictor is one of the world's largest vertebrate carnivores and is often found in urban areas in the city of Manaus, Brazil. The morphological identification of ticks collected from 27 snakes indicated the occurrence of Amblyomma dissimile Koch 1844 on all individuals sampled. In contrast, Amblyomma rotundatum Koch was found on only two snakes. An analysis of the 16S rRNA molecular marker confirmed the morphological identification of these ectoparasites.

<I>Anathallis roseopapillosa</I> (Orchidaceae - Pleurothallidinae), a New Species from the Central Amazon Region

Abstract A new species of Anathallis, A. roseopapillosa, is described from the central Brazilian Amazon. It is morphologically related to A. gracilenta, but differs by having shorter racemes arising abaxially from the leaves, with flowers opening one at a time, petals with a papillose apex, and an oblong-elliptic to ovate-elliptic lip, which is often obscurely tri-lobed. We also provide evidence of the phylogenetic position of the new species in the subtribe Pleurothallidinae by means of a cladistic analysis of nuclear DNA sequence data (ITS).

Effects of urbanization on stream habitats and associated adult dragonfly and damselfly communities in central Brazilian Amazonia

Thirty streams, located in Manaus in the central part of Brazilian Amazonia, were examined to evaluate the correlations between environmental integrity and the local communities of adult dragonflies and damselflies. The presence of damselflies would have a positive correlation with environmental integrity, and dragonflies a negative one due to their contrasting ecophysiological requirements. The environmental integrity of each site was estimated based on the Habitat integrity index (HII), which was modified for this study in an urban area. The hypothesis that would be differences in assemblage composition between streams in differently urbanized areas was supported, possibly because most damselfly species are considered to be specialists that are found in pristine habitats, whereas dragonflies seem to be generalists and are likely to be found in disturbed environments. The ordination indicated systematic differences in community composition based on the degree of conservation of the environment, with the communities found in well-preserved habitats being distinct from those found in intermediate and degraded ones. Differences in the composition of odonate communities reflect differences in the integrity of the environment, but they can also provide a measure of the intensity of impacts, thus contributing to the development of effective conservation strategies. In addition, the HII, which is applied rapidly and easily, provides environmental managers with an objective measure of the degree of alteration of aquatic habitats. Maintenance of forest cover along watercourses is clearly essential for the conservation of hydrological resources and the aquatic organisms that depend on these environments.

Phyllostomid Bat Assemblage Structure in Amazonian Flooded and Unflooded Forests

AbstractIn Amazonia, the assemblages of several taxa differ significantly between upland terra firme and white‐water flooded várzea forests, but little is known about the diversity and distribution of bats in these two forest types. We compare the spatio‐temporal patterns of bat assemblage composition and structure in adjacent terra firme and várzea forests in the lower Purus River region of central Brazilian Amazonia. Bats were sampled using mist nets at five sites in each forest type during 40 nights (2400 net‐hours). We captured 1069 bats representing 42 species and Phyllostomidae bats comprised 99.3 percent of all captures. The bat assemblages in várzea and terra firme forests were significantly different, mainly due to a marked dissimilarity in species composition and in the number of captures during high‐water season. In addition, bat assemblages within forest types differed significantly between seasons for both terra firme and várzea. Frugivores dominated the bat assemblages in both forest types. Overall guild structure did not change between várzea and terra firme or between seasons, but frugivore and animalivore abundance increased significantly in várzea forest during the inundation. The difference in assemblage structure observed in the high‐water season is probably caused by the annual várzea flooding, which provides an effective barrier to the persistence of many understory bats. We also hypothesize that some bat species may undertake seasonal movements between forest types in response to fruit abundance, and our results further underline the importance of floodplain habitats for the conservation of species in the Amazon.

Giant otter population responses to habitat expansion and degradation induced by a mega hydroelectric dam

Large hydroelectric dams are major drivers of habitat loss and degradation in lowland Amazonia. Hydroelectric reservoirs reduce the habitat available for terrestrial species, but create new open-water and shoreline lake habitat that can potentially boost populations of aquatic and semi-aquatic species, such as the threatened giant otter (Pteronura brasiliensis). To assess the impacts of mega-dams on this apex-predator, we surveyed the giant otter population across the 443,772-hectare Balbina Hydroelectric Reservoir of central Brazilian Amazonia between 14 and 25years after this reservoir creation. We compared changes in habitat area and estimated giant otter population size between the reservoir pre- and post-filling stages. The Balbina dam created ∼3525 islands and increased the open-water surface and total reservoir perimeter available to otters by a factor of 62.7 and 8.9, respectively. Some 25years after damming, however, the estimated post-filling giant otter population size was only twice greater than that estimated before filling and 4.5 times smaller than would be predicted given the total available habitat area and density of dens quantified at a neighbouring undisturbed area used as a surrogate of the pre-filling phase. The observed mismatch between the proportional increase in otter population size and the much greater newly available reservoir habitat area is likely due to low habitat quality in terms of low fish prey productivity and scarcity of suitable sites for denning and territory demarcation. This should be considered in strategic environmental impact assessments of planned hydroelectric dams and in managing existing and future hydropower development in lowland tropical forests.

Variation in tropical bird survival across longitude and guilds: a case study from the Amazon

Survival estimates of tropical birds have been used to examine life‐history variation across latitudes and dietary guilds. Here, we provide apparent survival estimates of 31 rainforest species from central Amazonian Brazil and compare our results with estimates from Ecuador, Peru (western Amazonia) and French Guiana (eastern Amazonia) to examine geographic variation in demography. Our averaged annual survival estimate for central Amazonian species (ϕ= 0.59, SE = 0.10) was concordant with previously published estimates from the western Amazon (ϕ= 0.58, SE = 0.02), and eastern Amazon (ϕ= 0.63, SE = 0.06). Two predominate demographic patterns were detected across the study areas: within species, survival was highest or lowest in eastern or western Amazonia, but rarely in central Amazonia. The most striking demographic variation was exhibited by Pithys albifrons, for which apparent survival estimates were nearly twice as high in eastern Amazonia (ϕ= 0.80, SE = 0.06) than in western Amazonia (ϕ= 0.42, SE = 0.06) but intermediate in central Amazonia (ϕ= 0.54, SE = 0.04). Although variation in survival may be associated with differences in life history characteristics, our analysis of flocking guild, body size, and nest architecture revealed only moderate differences in survival associated with nest architecture. These results suggest that geographic variation in population processes may be significant for widespread Amazonian species.

Extension of the geographic range of Ateles chamek (Primates, Atelidae): evidence of river-barrier crossing by an amazonian primate

The black-faced black spider monkey (Ateles chamek) is endangered because of hunting and habitat loss. There are many gaps in our understanding of its geographic distribution. The Ucayali-Solimões-Amazon fluvial complex is currently recognized as the northern boundary of the species' range, although published reports have indicated that it occurs north of the Rio Solimões. In this study we investigate published records, generate new field records, and assess the current information concerning the northern boundary of this species' range. We conducted the study at the Mamirauá Sustainable Development Reserve in the central Brazilian Amazon, an area of 1,124,000 ha that consists entirely of Amazonian flooded forest (várzea). We collected data on the occurrence of the species from museum specimens and through field surveys, including interviews with local residents, direct observations, and the collection of new museum specimens. We confirmed the presence of A. chamek at 17 locations in the reserve, one of which was an island formed by a river bend cut-off that would have effectively taken any resident spider to the (new) north bank of the Solimões. We therefore conclude that fluvial dynamics were involved in creating the conditions for the dispersal and colonization of the species on the northern bank of the Rio Solimões. The data we present extends the known distribution of the species and increases its representation in protected areas.

Decay of interspecific avian flock networks along a disturbance gradient in Amazonia

Our understanding of how anthropogenic habitat change shapes species interactions is in its infancy. This is in large part because analytical approaches such as network theory have only recently been applied to characterize complex community dynamics. Network models are a powerful tool for quantifying how ecological interactions are affected by habitat modification because they provide metrics that quantify community structure and function. Here, we examine how large-scale habitat alteration has affected ecological interactions among mixed-species flocking birds in Amazonian rainforest. These flocks provide a model system for investigating how habitat heterogeneity influences non-trophic interactions and the subsequent social structure of forest-dependent mixed-species bird flocks. We analyse 21 flock interaction networks throughout a mosaic of primary forest, fragments of varying sizes and secondary forest (SF) at the Biological Dynamics of Forest Fragments Project in central Amazonian Brazil. Habitat type had a strong effect on network structure at the levels of both species and flock. Frequency of associations among species, as summarized by weighted degree, declined with increasing levels of forest fragmentation and SF. At the flock level, clustering coefficients and overall attendance positively correlated with mean vegetation height, indicating a strong effect of habitat structure on flock cohesion and stability. Prior research has shown that trophic interactions are often resilient to large-scale changes in habitat structure because species are ecologically redundant. By contrast, our results suggest that behavioural interactions and the structure of non-trophic networks are highly sensitive to environmental change. Thus, a more nuanced, system-by-system approach may be needed when thinking about the resiliency of ecological networks.

Echolocation of the big red bat Lasiurus egregius (Chiroptera: Vespertilionidae) and first record from the Central Brazilian Amazon

Lasiurus egregius (Peters, 1870) is a rare Neotropical vespertilionid bat and virtually no data on its ecology and echolocation calls are currently available. We report the capture of four individuals in the Central Amazon, representing the first record for the region and a significant (> 800 km) expansion of the species’ known range. Echolocation calls, recorded for the first time under natural conditions, were 1.5–8 ms in duration, and characterized by high mean bandwidth (18 kHz) and a mean frequency of maximum energy of 30 kHz.

A New Species ofArapaima(Osteoglossomorpha: Osteoglossidae) from the Solimões River, Amazonas State, Brazil

A new species of Arapaima has been discovered from the central Amazon of Brazil. This new taxon is readily distinguished from all other Arapaima by the following three characters: 1) dorsalmost lateralis sensory cavity on preopercle extremely slender (vs. broadly oval or nearly rectangular in other nominal taxa); 2) ventrolateral margin of head where third infraorbital meets anterior limb of preopercle strongly angled such that ventral surface of head is almost flat (vs. ventrolateral margin of head relatively rounded); and 3) anterior third of dorsal-fin base covered with an enlarged, thickened sheath that hides anterior dorsal-fin rays when adpressed (vs. no thickened sheath on anterior base of dorsal fin and anterior dorsal-fin rays visible when adpressed). Distinguished from all other Arapaima except A. agassizii by having extremely long fourth infraorbital. Distinguished from A. arapaima and all other examined non-type specimens by notably slender body (the holotypes of A. gigas, A. mapae, and A. agassizii also have slender bodies). Further distinguished from A. mapae and A. agassizii by having relatively deep caudal peduncle (6.0% SL, vs. ∼4.0% in latter two taxa), and from A. gigas by having dentary teeth in a single row (vs. dentary teeth in 2–2.5 irregular rows). This species was collected near the confluence of the Solimões and Purus rivers in Amazonas State, Brazil. It is the first new species of Arapaima to be described since 1847, and comparisons with Arapaima from Mamirauá Reserve demonstrate that there are at least two species of Arapaima present in Amazonas State.