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Understanding of resource requirements of vulnerable species is key for conservation planning. Here, we used stable carbon (δ

Comprehension of the benefits involved in mutualisms is crucial to disentangle the role of interactions in the structure and functioning of populations, communities and ecosystems. In ant-plant mutualisms, benefits provided by plants to ants are immediately recognizable, but reverse benefits are less obvious, conditional and accumulate over longer time spans. Here we tested the hypothesis that the ant Azteca muelleri simultaneously provides multiple benefits to its host plant (Cecropia glaziovii), ultimately increasing plant performance. We planted seedlings and experimentally prevented ant colonization for half of them. Over 4.5 years we quantified the effects of ant presence or absence on plant growth, herbivory levels, fungal infection, fertilization via ant debris and changes in defense strategies. Ant colonization increased plant height by 125% compared to ant-free plants. Such an improvement in plant performance can be explained because plants with ants faced less herbivory, lower prevalence of pathogenic fungi, invested less in foliar trichomes and had more foliar nitrogen. We thus confirmed that ant mutualists provide cumulative benefits including nutritional benefits, effective defense and lower investment into other defenses – which result in increased plant growth. We highlight the importance of long-term experiments that simultaneously evaluate a multiplicity of potential ant effects to better understand their relative contribution to the performance of the mutualistic partner.

Made available in DSpace on 2021-06-25T15:01:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-09 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Deforestation and habitat loss resulting from land use changes are some of the utmost anthropogenic impacts that threaten tropical birds in human-modified landscapes (HMLs). The degree of these impacts on birds' diet, habitat use, and ecological niche can be measured by isotopic analysis. We investigated whether the isotopic niche width, food resources, and habitat use of bird trophic guilds differed between HMLs and natural landscapes (NLs) using stable carbon (delta C-13) and nitrogen isotopes (delta N-15). We analyzed feathers of 851 bird individuals from 28 landscapes in the Brazilian Atlantic Forest. We classified landscapes into two groups according to the percentage of forest cover (HMLs = 47%), and compared the isotopic niche width and mean values of delta C-13 and delta N-15 for each guild between landscape types. The niches of frugivores, insectivores, nectarivores, and omnivores were narrower in HMLs, whereas granivores showed the opposite pattern. In HMLs, nectarivores showed a reduction of 44% in niche width, while granivores presented an expansion of 26%. Individuals in HMLs consumed more resources from agricultural areas (C-4 plants), but almost all guilds showed a preference for forest resources (C-3 plants) in both landscape types, except granivores. Degraded and fragmented landscapes typically present a lower availability of habitat and food resources for many species, which was reflected by the reduction in niche width of birds in HMLs. Therefore, to protect the diversity of guilds in HMLs, landscape management strategies that offer birds more diverse habitats must be implemented in tropical regions. Univ Sao Paulo, Dept Ciencias Florestais, Lab Ecol Manejo & Conservaeao Fauna Silvestre LEM, Escola Super Agr Luiz de Queiroz, Av Padua Dias 11, BR-13418900 Piracicaba, SP, Brazil Univ Sao Paulo, Ctr Energia Nucl Agr, Lab Ecol Isotop, Av Centenario 303, BR-13416903 Piracicaba, SP, Brazil Univ Sao Paulo, Museu Zool, Secao Aves, Av Nazare 481, BR-04263000 Sao Paulo, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Biodiversidade, Av 24-A 1515, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Campinas, Inst Biol, Dept Biol Anim, Lab Interacoes Vertebrados Plantas, Rua Monteiro Lobato 255, BR-13083862 Campinas, SP, Brazil Univ Estadual Paulista, Fac Ciencias, Dept Ciencias Biol, Av Eng Luiz Edmundo Carrijo Coube 14-01, BR-17033360 Bauru, SP, Brazil Univ Fed Sao Carlos, Ctr Ciencias & Tecnol Sustentabilidade, Dept Ciencias Ambientais, Rodovia Joao Leme dos Santos SP-264 Km 110, BR-18052780 Sorocaba, SP, Brazil Inst Chico Mendes Conservacao Biodiversidade, Ctr Nacl Pesquisa & Conservacao Mamiferos Carnivo, Estr Municipal Hisaichi Takebayashi 8600, BR-12952011 Atibaia, SP, Brazil Inst Nacl Mata Atlantica, Av Jose Ruschi 4, BR-29650000 Santa Teresa, ES, Brazil Inst Procarnivoros, Av Horacio Netto 1030,Parque Edmundo Zanoni, BR-12945010 Atibaia, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Biodiversidade, Av 24-A 1515, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Paulista, Fac Ciencias, Dept Ciencias Biol, Av Eng Luiz Edmundo Carrijo Coube 14-01, BR-17033360 Bauru, SP, Brazil FAPESP: 2010/05343-5 FAPESP: 2011/06782-5 FAPESP: 2011/04046-0 FAPESP: 2018-05970-1 FAPESP: 2020/076190 CAPES: 88882.328664/2019-01 CNPq: 300744/2020-0 CAPES: 001-CAPES PNPD 2013/1723 CNPq: 308632/2018-4 CNPq: 302291/2015-6 CNPq: 308337/2019-0 CNPq: 304742/2019-8

The present study aimed to investigate the role of four non-native invertebrates in supporting fish biomass as well as their influence on the carbon flow into the Volta Grande reservoir food web. The fish samples were carried out quarterly between October 2015 and July 2016 using gillnets. At the sampled sites, four non-native invertebrates (golden mussel, Asian clam, trumpet snail and Amazonian prawn), which are potential prey for fish in the Volta Grande reservoir, were collected by targeted sampling using a Petersen-type bottom dredger and semi-circular sieves. The gut contents of the fish were collected and analyzed under stereoscope, and samples of muscle tissue of these fish, as well as the four non-native invertebrate species sampled, were submitted for isotopic analysis. Results obtained by the present study, by both gut content and stable isotopic analyses, pointed to a trophic structure where non-native species represent not only a strong component of the fish community, but also their main carbon source. Based on gut contents and isotopic mixing models, we found that together, non-native prey are essential carbon sources for the fish fauna, fuelling more than 40.0% of the biomass in four dominant fish species. The consumption rate of non-native bivalves by the native omnivorous fish Leporinus friderici suggested these filter-feeding organisms potentially constitute an important trophic connection between littoral consumers and pelagic energy sources. In addition, non-native prey were also prominent carbon sources for non-native fish, fuelling more than half of the biomass in peacock bass and silver croaker, suggesting these prey have a fundamental role in maintaining non-native fish populations in this system. Our results may help to understand fundamental ecological issues bringing to light the extent to which these new combinations of species influence the energy flow and ecosystem properties of the Volta Grande reservoir.

By analyzing 6,480 tree leaf samples from 57 sites within Brazilian biomes, we considered whether vegetation types in terrestrial ecosystems reflect biogeochemical diversity and whether they fit into a leaf economics spectrum (LES). To achieve this, we investigated the relations among leaf carbon (C) and nitrogen (N) concentrations, their isotope natural abundance and C:N ratio. In addition, we tested their correlations with mean annual temperature (MAT) and precipitation (MAP), as climatic factors. We found consistent differences in the C and N concentrations and their isotopic composition among the vegetation types. MAP is the main climatic driver of changes in N, C:N ratio, δ15N, and δ13C, correlating negatively with N and positively with C:N ratio. These relations show that these biomes follow an LES. The Caatinga had the highest δ15N values, suggesting that N residence time in soil is longer due to low leaching and plant uptake. We observed that MAP is not the only factor influencing δ13C values in different biomes; instead canopy effect probably explains the highest values observed in the Cerrado. Our results reinforce earlier findings that life diversity in the tropics reflects biogeochemistry diversity and leaf δ15N opens the possibility for investigating plant trade-offs dictated by the LES. Finally, we expect our findings to contribute to a better understanding of the tropics in global climate models.

Although stable isotopes have been increasingly used in ornithology since 1980 in many places, Brazil has been slow in adopting this methodology, especially when it comes to terrestrial birds. The most common elements in bird ecology studies are carbon, nitrogen, hydrogen, and oxygen stable isotopes, which provide information on diet, trophic interactions, habitat use, migration, geographic patterns, and physiology. It is important that Brazilian ornithologists become aware of the potential of stable isotope analysis in ecological studies, and the shortcomings of this tool. The use of stable isotopes to study bird ecology has great potential in Brazil, since many ecological questions about Neotropical birds can be addressed by it (e.g., resource and habitat use, migratory routes, isotopic niches, anthropogenic impacts, individual specialization). Brazilian museums and other Natural History collections can provide samples to study long-term temporal dynamics in bird ecology. Additionally, the integration of avian tissue sample information into a database may increase the collaboration among researchers and promote sample reuse in a variety of studies. All biomes in Brazil have been under pressure from anthropogenic impacts (e.g., land-use change, habitat loss, fragmentation, intensive agriculture), affecting several taxa, including terrestrial birds. Considering the negative effects of human expansion over natural areas and that stable isotopes provide useful ecological information, ornithologists in Brazil should increase their use of this tool in the future.

The trophic plasticity of most fish species of Astyanax Baird & Girard, 1854 in response to environmental changes and resource availability is high. This work evaluates the differences in the trophic characteristics of two congeneric species, Astyanaxtaeniatus (Jenyns, 1842) and Astyanaxlacustris (Lütken, 1875), in Rio das Velhas Basin, which is highly impacted by the discharge of sewage from the Metropolitan Region of Belo Horizonte (MRBH). Eight sites were sampled and grouped into three regions: upper course (two sites upstream of the MRBH); middle course (three sites located in the middle portion of the Rio das Velhas, region with greater influence of the MRBH), and lower course (three sites downstream of the MRBH). Samples of fish and food resources were collected from all sites to obtain the isotopic composition of nitrogen (δ15N) and carbon (δ13C), and the stomach contents of the two species was analized. The most common items in the stomach of A.lacustris and A.taeniatus, respectively, were from plants and insects, followed by algae/periphyton (especially at the low course of Rio das Velhas). In contrast, stable isotope analyses indicated that algae (in polluted sites) and periphyton (in least-disturbed sites) were best assimilated both species. Both analyses indicated that the trophic niches of the two species overlap more in more polluted sites relative to less polluted sites. Astyanaxtaeniatus and A.lacustris only presented different isotopic composition of carbon and nitrogen in the upper course of the Rio das Velhas, probably in response to the greater diversity of food items consumed by each species. In the other regions, the species presented similar isotopic signatures, with δ15N and δ13C notably enriched in the most polluted regions (middle and low course). Our results suggest that pollution acts by increasing trophic niche overlap of these species, altering the type of resources most assimilated, and promoting a greater enrichment of δ15N in fish and resources.

The aim of this study was to test the hypothesis that a widespread non-native fish species in Brazil displays opportunistic feeding behavior and changes its diet according to environmental conditions. We compared the diet, feeding selectivity, carbon assimilation, trophic niche, and trophic level of Knodus moenkhausii (a small non-native characid fish species of Upper Parana River) in streams surrounded by natural riparian vegetation (natural cover streams) and in streams impacted by pasture. We analyzed stomach contents and stable isotopes (carbon and nitrogen), simultaneously. Overall, insects were the most common food items (> 65%). In natural cover streams, K. moenkhausii showed higher selectivity among aquatic macroinvertebrates consumed, while in pasture streams, they fed on the most abundant groups. The proportion of feeding groups assimilated by K. moenkhausii and the proportion of primary sources consumed by each feeding group of macroinvertebrates also varied between natural cover and pasture streams, as indicated by stable isotopes. In natural cover streams, fine and coarse particulate organic matter accounted for approximately 80% of K. moenkhausii’s diet, while in pasture streams, algae and periphyton also contributed greatly. As a result, K. moenkhausii occupied a higher trophic level and exhibited a broader niche width in pasture streams. We conclude that K. moenkhausii presents feeding selectivity with capacity to alter the trophic niche depending on environmental conditions. Such opportunism could be one of the reasons underpinning the abundance and wide distribution of this invasive species.

Eutrophic estuaries receive organic matter (OM) inputs from multiple sources. This study evaluated the distribution and origin of sedimentary OM in an eutrophic estuary (Pina Sound, NE Brazil). Thirteen samples were collected in the sublittoral in addition to major local sources. Biochemical (chlorophyll - Chl), elemental [(C/N)a and C/S ratios] and isotopic (δ 15N and δ 13C) analyses were carried out for characterizing OM and redox conditions. The SIAR mixing model was used to quantify contribution from main sources. At Pina Sound, distribution of OM is associated with mud, reflecting the hydrodynamics control on deposition of suspended particles. Microphytobenthic production is limited ([Chl a] < 1000 µg/g organic carbon) in the sublittoral where the Chl degradation products prevail (mean [Pheopigments] = 2643 ± 958 µg/g organic carbon). Anoxic conditions (C/S ratio ≈ 2) are typically observed in sediments of deeper portions of Pina Sound. Such sediments receive high organic loads and are subject to poor water renewal. According to SIAR mixing model, sedimentary OM of Pina Sound is composed of, on average: 50% phytoplankton, 24% sewage and 26% C3 plants. This reflects fertilization of Pina Sound with high loads of untreated sewage. Pina Sound has a great potential to retain sewage-derived OM.

Made available in DSpace on 2022-04-28T19:44:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The intensification of land-use changes in tropical forests during the 20th century, mainly caused by deforestation for agricultural uses, had an overwhelming influence on bird assemblages. However, how these historical anthropogenic changes have impacted the habitat use and diet of tropical birds is poorly known. Stable isotope analysis (δ13C and δ15N) can be useful in this regard since it provides information not only on the habitat and food resource use but also insights on the dietary niche of species. Here, we aimed to evaluate whether centenary anthropogenic impacts, mainly caused by changes in landscape composition, have affected the resource and habitat use and isotopic niche width of Neotropical birds in a region that comprises two biodiversity hotspots – the Atlantic Forest and Cerrado in southeastern Brazil. We found that the niche width of all bird guilds (frugivore, granivore, insectivore, nectarivore and omnivore) was largely reduced (28–70%) from the 20th century until recently. This niche width reduction was likely associated with historical anthropogenic impacts (e.g. fragmentation, forest loss and change in agricultural practices), which are responsible for the decrease in the availability of habitat and food resources. Moreover, the mean values of δ15N decreased over the years in all bird guilds, which might be attributed to the expansion of agricultural areas and the increase in the use of synthetic nitrogen-based fertilizers. All the analyzed species, even though some of them are diet and habitat generalists, were strongly influenced by centenary anthropogenic actions. Our results show the consequences of human-induced changes in land use on the diet and habitat use of tropical birds that persist in fragmented landscapes, which might compromise their long-term survival and provide useful information to the conservation strategies of bird assemblages in modern landscapes. Laboratório de Ecologia Manejo e Conservação de Fauna Silvestre (LEMaC) Depto de Ciências Florestais Escola Superior de Agricultura ‘Luiz de Queiroz’ Centro Nacional de Pesquisa e Conservação de Mamíferos Carnívoros Inst. Chico Mendes de Conservação da Biodiversidade Inst. Nacional da Mata Atlântica Seção de Aves Museu de Zoologia da Univ. de São Paulo Laboratório de Ecologia Isotópica Centro de Energia Nuclear na Agricultura – Univ. de São Paulo Laboratório de Interações Vertebrados Plantas Depto de Biologia Animal Inst. de Biologia Univ. Estadual de Campinas Inst. de Biociências Depto de Zoologia Univ. Estadual Paulista Inst. de Biociências Depto de Zoologia Univ. Estadual Paulista

Made available in DSpace on 2022-04-29T08:38:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 How species persist in fragmented habitats is essential to understanding species resilience in response to increasing anthropogenic pressures. It has been suggested that expansion in dietary niche allows populations to persist in human-modified landscapes, yet this hypothesis has been poorly tested in highly diverse ecosystems such as tropical forests where frugivory is ubiquitous. Here, we measured dietary niche expansion of a large forest-dwelling mammal, the white-lipped peccary (Tayassu pecari), in the Atlantic Forest, Brazil, by comparing its diet using stable carbon (δ13C) and nitrogen (δ15N) isotopes. We collected hair of white-lipped peccaries in three continuous and three fragmented forests and compared δ13C and δ15N values, resource use and isotopic niches among populations and between forest types. We also tested the relationship between isotopic values of the populations and the forest cover percentage. White-lipped peccaries fed mainly on forest sources (C3 resources), especially in continuous forests, but 28% of the individuals in fragmented sites also incorporated C4 resources to some extent. In fragmented forests, the populations had isotopic niches from 3- to 3.6-fold the size of those in continuous forests. This niche expansion was due to the consumption of food items with higher δ15N values and C4 crops. Differences among populations were larger among fragmented forests, suggesting variable site-specific strategies to cope with habitat loss. The mean isotopic values of white-lipped peccary populations were negatively correlated with the loss of forest cover. Some small forest fragments might still retain relatively high habitat quality, and white-lipped peccaries might be able to capitalize on such variety of resources, shifting their diets from those observed in continuous forests. We suggest that high dietary flexibility and dietary expansion toward consumption of non-forest resources might facilitate the persistence of large frugivores in fragmented habitats. Instituto Pró-Carnívoros, São Paulo Centro Nacional de Pesquisa e Conservação de Mamíferos Carnívoros (CENAP) Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio), São Paulo Instituto de Biociências Departamento de Biodiversidade Universidade Estadual Paulista (UNESP), São Paulo Department of Aquatic Ecology Netherlands Institute of Ecology Earth & Environmental Sciences Vanderbilt University Centro de Ciências Naturais e Humanas (CCNH) Universidade Federal do ABC (UFABC), São Paulo Peccary Project/IUCN/SSC Peccary Specialist Group Fundação Neotrópica do Brasil Department of Environmental Studies Wofford College Mão na Mata – Manejo e Soluções Ambientais, São Paulo Centro de Isótopos Estáveis Instituto de Biociências Universidade Estadual Paulista, São Paulo Laboratório de Ecologia Isotópica Centro de Energia Nuclear na Agricultura Universidade de São Paulo, São Paulo Laboratório de Ecologia Manejo e Conservação de Fauna Silvestre (LEMaC) Departamento de Ciências Florestais Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ) Universidade de São Paulo (USP), São Paulo Department of Biology University of Miami Instituto de Biociências Departamento de Biodiversidade Universidade Estadual Paulista (UNESP), São Paulo Centro de Isótopos Estáveis Instituto de Biociências Universidade Estadual Paulista, São Paulo

Made available in DSpace on 2021-06-25T11:44:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The objective of this study was to evaluate the grazing of goats in a grass monoculture system and in intercropping systems of grass + legumes. A randomized block design was adopted, with the treatments arranged in a split-plots scheme. The plots consisted of three cropping systems: monoculture-Andropogon gayanus cv. Planaltina; mixture I-A. gayanus cv. Planaltina +Stylosanthes cv. Campo Grande; and mixture II-A. gayanus cv. Planaltina +Calopogonium mucunoides. The subplots consisted of two grazing cycles. The highest (P=0.04) total forage mass (TFM) was recorded in the mixture I (A. gayanus cv. Planaltina+Stylosanthes. cv. Campo Grande), which was 2.6 +/- 0.1 tons DM/ha. The crude protein (CP) was lower in the monoculture which also showed the highest content of neutral detergent fiber (NDF). The grazing time in the monoculture was the longest (8.23 +/- 1.14 h). The goats used a longer time for rumination (P

Historically, anthropogenic fixed nitrogen has been purposely increased to benefit food production and global development. One consequence of this increase has been to raise concentrations of nitrogen in aquatic ecosystems. To evaluate whether nitrogen pollution promotes changes in the estimates of niche space of fish communities, we examined 16 sites along a Brazilian river basin highly impacted by anthropogenic activities, especially discharge of domestic and industrial sewage from a region with more than 5 million inhabitants. We analysed the carbon (δ13C) and nitrogen (δ15N) isotope ratios of fish species and both autochthonous (periphyton) and allochthonous (course and fine particulate organic matter) basal food resources. To estimate the magnitude of nitrogen pollution, we measured the nitrate and ammonium concentrations at each site. Sampling was conducted in the dry and wet seasons to evaluate the influence of seasonality. Nitrogen pollution generally increased estimates of niche space, and seasonality influenced only the niche estimates of fish communities from polluted sites. In addition, isotopic analyses of nitrogen polluted sites yielded unrealistic estimates of trophic positioning (detritivores at the top of the food web). We conclude that changes in niche space estimates reflect both alterations in baseline isotopic values and differential trophic behaviour among fishes. Our study suggests that under conditions of high pollution, other factors appear to influence isotopic estimates of niche, such as isotopically distinct sources that have not been sampled, and/or differences in δ15N turnover rates between fish tissue and basal resources, creating isotopic baselines that are challenging to interpret.

Deforestation and habitat loss resulting from land use changes are some of the utmost anthropogenic impacts that threaten tropical birds in human-modified landscapes (HMLs). The degree of these impacts on birds' diet, habitat use, and ecological niche can be measured by isotopic analysis. We investigated whether the isotopic niche width, food resources, and habitat use of bird trophic guilds differed between HMLs and natural landscapes (NLs) using stable carbon (δ

The proliferation of native, alien, invasive and domestic species provide novel and abundant food resources for the common vampire bat (Desmodus rotundus) that could alter its prey preference. Based on the analysis of carbon and nitrogen stable isotopes, we report the prey choice of D. rotundus on introduced mammals in an tropical land-bridge island where the domestic animals were removed and 100 individuals of 15 mammal species were intentionally introduced. Our analysis shows that, D. rotundus on Anchieta Island were more likely to prey upon species from open habitats (mean value of −14.8‰), i.e., animals with high δ13C values characterized by the consumption of C4 resources. As expected for a top predator species, δ15N values for D. rotundus were higher (mean value of 8.2‰) and overlapped the niche of the capybaras (Hydrochoerus hydrochaeris) from the Anchieta Island, while it was distant from coatis, and also from those potential prey from the preserved area in the mainland, including the capybaras, indicating that among all potential mammalian prey species, they fed exclusively on capybaras, the highest mammalian biomass on island. Based on previous information on human occupation, the domestic animals present on Anchieta island might be the main prey of D. rotundus and responsible for maintaining a viable population. As the capybaras were introduced only 36 years ago, this suggests a rapid prey shift due to anthropogenic disturbances, which has allowed common vampire bats to successfully exploit them. Literature records also show that common vampire bats were not captured in preserved areas of the mainland which are near Anchieta Island indicating that the percentage of capture of D. rotundus is usually low in natural forested habitats where potential prey are scattered. As three individuals of introduced capybaras were confirmed died from bat rabies viruses (RABV) in 2020, we suggest periodic monitoring of bat rabies viruses in common vampire bat populations on Anchieta Island and areas nearby, in order to quantify the magnitude of the outbreak area and develop strategies for controlling, especially considering that the island and areas nearby is frequently visited by tourists. We highlighted that this prey choice is context-dependent, and possibly influenced by the removal of domestic animals, the explosive population growth of introduced capybaras combined with their predictable foraging behavior.

Anthropogenic activities can have a great influence on water quality and in the availability of habitat and food resources, which can promote changes in the trophic diversity and carbon sources sustaining aquatic communities. The objective of this study was to evaluate if the trophic diversity and the main carbon sources sustaining fish communities change along a pollution gradient. The study was carried out at eight sites distributed along the Rio das Velhas, a Brazilian river highly impacted by anthropogenic activities, in which the discharge of domestic and industrial sewage from the Metropolitan Region of Belo Horizonte (MRBH) presents a major source of pollution. Using carbon (δ13C) and nitrogen (δ15N) isotope ratios, we identified the major carbon sources/food sources of common fish species and calculated six metrics of trophic diversity. Autochthonous primary producers (algae, periphyton, and macrophytes) were the main carbon sources for all trophic guilds at all sites, but notably, sewage-derived organic matter was an additional significant carbon source to the fish community in the most polluted testing site. Here, the community was composed mainly by detritivorous and omnivorous fishes and exhibited greater ranges of carbon and nitrogen isotopic values, large total areas, high trophic diversity, small trophic redundancy, and less even distribution of trophic niches than the less polluted sites. We conclude that the trophic guilds, trophic diversity metrics, and carbon sources sustaining fish communities in the Rio das Velhas are highly influenced by the presence of pollution. Besides favoring omnivorous and detritivorous fishes, the input of sewage also provided an important food source to sustain the fish community from sites close to the MRBH.

Several previous studies on targeted food items using carbon and nitrogen stable isotope ratios in Brazil have revealed that many of the items investigated are adulterated, mislabeled or even fraud. Here, we present the first Brazilian isotopic baseline assessment that can be used not only in future forensic cases involving food authenticity, but also in human forensic anthropology studies. The &delta, 13C and &delta, 15N were determined in 1245 food items and 374 beverages, most of them made in Brazil. The average &delta, 15N of C3 plants were &minus, 26.7 &plusmn, 1.5&permil, and 3.9 &plusmn, 3.9&permil, respectively, while the average &delta, 15N of C4 plants were &minus, 11.5 &plusmn, 0.8&permil, and 4.6 &plusmn, 2.6&permil, respectively. The &delta, 15N of plant-based processed foods were &minus, 21.8 &plusmn, 4.8&permil, 2.7&permil, respectively. The average &delta, 15N of meat, including beef, poultry, pork and lamb were -16.6 &plusmn, 4.7&permil, and 5.2 &plusmn, respectively, while the &delta, 15N of animal-based processed foods were &minus, 17.9 &plusmn, 3.3&permil, and 3.3 &plusmn, 3.5&permil, 13C of beverages, including beer and wine was &minus, 22.5 &plusmn, 3.1&permil, We verified that C-C4 constitutes a large proportion of fresh meat, dairy products, as well as animal and plant-based processed foods. The reasons behind this high proportion will be addressed in this study.

Integrated farming systems are sustainable strategies to intensify land productivity by combining annual crop, livestock and/or forestry activities in different spatio-temporal arrangements. Therefore, they may help tackle global food and energy insecurity and climate change in the coming decades. We investigated the effects of integrated crop-livestock (ICL) and integrated crop-livestock-forestry (ICLF) systems on quantity, quality, and origin of soil organic matter (SOM) in southeastern Brazil. A native forest and an extensive low-grazing intensity pasture system were used as references. In integrated systems, corn (Zea mays) was alternated with two consecutive years of piata grass (Urochloa bryzantha) for cattle grazing. In ICLF, eucalyptus trees (Eucalyptus urograndis) were planted in simple rows of 15 × 2 m. Soil sampling was performed three times; in 2014, after two years of grazing; in 2015, after crop cultivation; and in 2016, after a successive grazing year, to evaluate chemical and physical composition changes of organic matter (C, N, δ13C, δ15N, and organic matter fractions) with time. Our findings showed that from 2010 to 2016, all systems (extensive grazing, ICL and ICLF) promoted increments on soil C and N stocks. However, land intensification converting extensive low-grazing intensity pasture to ICL was the most promising strategy, increasing soil C stocks at the rate of 0.28 Mg C ha−1 yr−1 from 2010 to 2016. Annual crop cultivation (corn intercropped with piata grass) promoted high organic matter inputs on the soil, increasing the amount of soil labile organic matter fractions, which presented higher δ13C and lower δ15N values over time. SOM in the integrated farming systems was originated mainly from C4 plants. Therefore, optimizing development of piata grass and corn increases organic residue inputs and then, soil C and N stocks. In addition, the crop period increased soil fertility parameters, which favors plant growth, thus providing high labile C inputs to the soil. In contrast, land intensification by adding the forestry component into the system (i.e., conversion from ICL to ICLF) reduced soil C (-0.22 Mg C ha−1 yr−1) and N (-0.03 Mg N ha−1 yr−1) stocks from 2010 to 2016, likely due to the reduction of C and N inputs to the soil caused by limited growth of annual crop and grass species under tree shades. In conclusion, land use intensification through ICL system contributes towards a more efficient and low-C agriculture, whereas the studied ICLF system did not bring further benefits to increase the quantity and/or quality of SOM.

OBJECTIVE The main objective of this study is to investigate diet patterns among rural and urban populations of the Center-West, Northeast, and Amazon regions of Brazil through the carbon and nitrogen isotopic composition of fingernails, recognizing that the extent of market integration is a key driver of food consumption. MATERIALS AND METHODS In the Center-West, Northeast, and Amazon regions of Brazil, fingernails were sampled in clusters encompassing a major city, town, and rural village. A total of 2,133 fingernails were analyzed. Fingernails were clipped by donors using fingernail clippers. In the laboratory, samples were cleaned then weighed in small tin capsules before being isotopically analyzed for carbon and nitrogen. RESULTS The overall mean δ13 C and δ15 N were -19.7 ± 2.8‰ and 10.6 ± 1.1‰, respectively. In the more remote villages, where access to food markets is more challenging, lower δ13 C prevails, suggesting that Brazilian staple foods (rice, beans, and farinha) still dominate. In areas with easier access to food markets, δ13 C values were higher, suggesting a change to a diet based on C4 plants, typical of a Brazilian supermarket diet. The variability among inhabitants in the same location expressed by a significant inverse correlation between δ13 C and δ15 N fingernail values suggested that "market integration" does not affect everyone equally in each community. DISCUSSION AND CONCLUSION The nutrition transition has not yet reached some remote villages in these regions of Brazil or that the nutrition transition has not yet reached all residents of these remote villages. On the other hand, in several villages there is a considerable adherence to the supermarket diet or that some residents of these villages are already favoring processed food.

Land use changes in tropical forests intensified during the 20th century, mainly caused by deforestation for agricultural uses, which had an overwhelming influence on bird communities. However, there is a knowledge gap on how these historical anthropogenic changes have impacted habitat use and diet of tropical birds. On this regard, isotopic analysis can be useful since δ13C and δ15N values provides information of habitat and food resource use, and also isotopic niche of species. Here, we aimed to evaluate whether changes in landscape composition caused by centenary anthropogenic impacts have influenced the isotopic signatures and niche widths of birds in a Neotropical biodiversity hotspot, the Atlantic Forest, in southeastern Brazil. Our results showed that all bird guilds (frugivore, granivore, insectivore, nectarivore, omnivore) presented a large reduction (28-70%) in niche width from the twentieth century until contemporary. These reductions are likely associated with historical impacts (e.g. fragmentation and habitat loss), which are responsible for a decrease in the availability of food resources. There was also a reduction in the mean values of δ15N over the years in all guilds, which might be related to the expansion of agricultural areas and the increment in use of synthetic nitrogen fertilizers. Albeit some of the analyzed species are considered diet and habitat generalists, all of them showed to have been strongly influenced by anthropogenic actions throughout the years. Since these birds perform ecological functions in fragmented areas, we suggest an increase in conservation actions that ensure they do not vanish in the near future.

Made available in DSpace on 2021-06-25T15:38:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The proliferation of native, alien, invasive and domestic species offers enough novel and abundant food resources for the common vampire bat, Desmodus rotundus, to potentially alter preferences for prey. By reference to a stable-isotope analysis for carbon and nitrogen, we report here on the choices of introduced mammal prey made by D. rotundus residing on Anchieta Island a tropical land-bridge island from which domestic animals were removed and 100 individuals of 15 mammal species were introduced intentionally. Our analysis shows that the studied individuals of D. rotundus were more likely to prey upon species of open habitats (mean value of delta C-13 = -14.8 parts per thousand), that is, animals with high delta C-13 values characterising the consumption of C-4 resources. The delta N-15 values for D. rotundus were higher than expected, most likely similar to apex predator species (mean value of 8,2 parts per thousand) and overlapped the isotopic niche with capybaras (Hydrochoerus hydrochaeris) on the island. Values were in turn distant from those noted for coatis, as well as other potential prey from a preserved area on the mainland (capybaras included), indicating that, from among all the potential mammalian prey species, the studied bats were feeding exclusively on capybaras, which also represent the species with the greatest mammalian biomass on the island. Previous information regarding the time of human occupation suggests that the domestic animals then present on Anchieta Island might have been the main prey of D. rotundus and responsible for maintaining a viable population. As capybaras were introduced only 36 years ago, this suggests a rapid shift in predation preference induced by anthropogenic disturbances that have allowed D. rotundus to exploit these rodents successfully. Records in the literature further show that common vampire bats were not captured in preserved areas of the mainland close to Anchieta Island, indicating that the rate of capture characterising D. rotundus is usually low in natural forested habitats where potential prey are scattered. As three individuals of the introduced population of capybaras were confirmed to have died from bat rabies virus (RABV) in 2020, we advocate periodic monitoring for bat rabies viruses in the D. rotundus population on Anchieta Island (as well as nearby areas), so that the magnitude of the outbreak may be determined mid control strategies developed. Such actions are all the more important given that both the island and nearby areas are frequented by tourists. We highlight that the prey choice indicated here is context-dependent, and possibly influenced by the removal of domestic animals, as well as the explosive population growth achieved by the introduced capybaras, in combination with the predictability of their foraging behaviour. Univ Estadual Paulista, Dept Biodiversidade, Inst Biociencias, BR-13506900 Rio Claro, SP, Brazil Univ Cambridge, Dept Zool, Conservat Sci Grp, Cambridge, England Univ Sao Paulo, Escola Super Agr Luiz de Queiroz, Lab Ecol Manejo & Conservacao Fauna Silvestre LEM, Av Padua Dias 11, BR-13418900 Piracicaba, SP, Brazil Inst Chico Mendes Conservacao Biodiversidade ICMB, Ctr Nacl Pesquisa & Conservacao Mamiferos Carnivo, Estr Municipal Hisaichi Takebayashi 8600, BR-12952011 Atibaia, SP, Brazil Inst Procarnivoros, Av Horcicio Neto 1030,Parque Edmundo Zanoni, Atibaia, SP, Brazil Univ Estadual Santa Cruz, Lab Ecol Aplicada Conservacao, Rodovia Ilheus Itabuna,Km 16 Salobrinho, BR-45662900 Ilheus, BA, Brazil Univ Sao Paulo, Lab Ecol Isotop, Ctr Energia Nucl Agr CENA, Av Centenario 303, BR-13416903 Piracicaba, SP, Brazil Univ Miami, Dept Biol, CP 33146, Coral Gables, FL 33124 USA Univ Estadual Paulista, Dept Biodiversidade, Inst Biociencias, BR-13506900 Rio Claro, SP, Brazil FAPESP: 2017/24252-0 FAPESP: 2019/00648-7 FAPESP: 2014/01986-0

The goal in this study was to evaluate the production of sheep and forage silvopastoral systems (SPSs) with cashew trees, compared to the production on grass monoculture. The treatments consisted of three grazing systems: one Massai grass monoculture (Panicum maximum cv Massai) (MONO), and two SPSs: intercrop of Massai grass + cashew tree (Anacardium occidentale) (SM) and intercrop of grass- Massai grass + Estilosantes Campo Grande (Stylosanthes capitata × S. macrocephala) + cashew tree (SME), in a completely randomized split plot design with four replications. The photosynthetically active radiation varied from 45 to 59% in SPSs, the presence of cashew trees created a microenvironment with lower temperatures and higher relative humidity throughout the day. Forage mass in the monoculture and in the SPSs was on average 2,116.65 kg dry matter (DM). ha-1; the participation of the legume in the forage mass was 44%. Greater stocking rate was found in the monoculture, however the gain per area was higher in the SME. In the SPSs, crude protein content of the grass increased by 46.2%, and there was a higher forage intake and weight gain of sheep, mainly in the system with legume. The silvopastoral system with cashew trees, Massai grass, estilosantes and sheep is feasible to optimize land use, with better gain per animal and area in relation to grass monoculture.

The origin of the organic matter was assessed in two estuaries in Eastern Amazon, Brazilian Northern Coast, under different hydrodynamic conditions. The isotopic composition ( δ 13 C; δ 15 N) and the elementary ratio (C/N) were determined in the sediments, in the suspended particulate material (SPM), as well as in the phytoplankton, plants and oysters. The ( δ 13 C) values have indicated that the sedimentary organic matter is a terrestrial–marine mix composed of terrigenous organic matter (75%) in the Para River estuary, as well as of marine organic matter (60%) in the Mocajuba River estuary. The estimates of sources recorded through δ 13 C data were partially confirmed through the correlation ( δ 15 N) versus C/N, which reflects the action of diagenetic and biological processes on the organic matter composition control. On the other hand, the high carbon content ( δ 13 C) found in Para River estuary samples is conclusive because it shows isotopic changes due to the anthropogenic processes in the region.

In this study we investigated the variation of soil attributes according to urban-related land cover categories. The study was carried out in an urbanized watershed located in the Brazilian subtropical region (Sorocaba Municipality, São Paulo). Soil samples were collected considering the land cover category for analysis of physical, chemical and isotopic attributes. The land cover influenced the soils attributes. Soils from wooded and grassed areas presented significant differences, especially for values of C isotopes. Soil bulk density was significantly altered. According to considered land cover mosaic in the study, we estimated 10,241.28 tons of C stored in the thickness 20 cm of the watershed (whole area), and this amount is almost a half of the total potential of C storing in the watershed. We stress that projects of planned land cover should effectively implemented in urbanized regions to effectively contribute in storing more C and improving the soil-related ecosystem services.

Although the understanding of biochar stability in soil has improved in recent years, there is a lack of knowledge about how both the soil and biochar carbon (C) mineralisations are affected as a function of biochar amount applied to soil. Thus, increasing amounts of biochar were added to a Quartzipsamment in order to evaluate its priming effect on soil organic carbon (SOC) decomposition. We hypothesised that biochar will increase negative priming on native SOC mineralisation as function of its application rate to soil. The biochar was produced from sugarcane straw through slow pyrolysis at 450 °C, and a laboratory incubation was conducted for 90 days with the following treatments: soil-alone (C3 source), biochar-alone (C4 source) and soil with biochar at rates equivalent to 0.4% (T1), 0.8% (T2) and 1.9% (T3) (w/w). In the first day of incubation, biochar amendment reduced soil C mineralisation rates from 58 to 88% compared to the soil-alone as a function of increasing biochar application rates. This reduction was mainly attributed to the mineralisation of easily available substrates from incomplete pyrolysis, which were preferentially used by soil micro-organisms at early stages of incubation. This effect, however, subsided after 7 days of incubation and it was not sufficient to induce co-metabolism of SOC decomposition, which were 43% (T1)–71% (T3) lower compared to the control (soil-alone) after 90 days of incubation. This was reflected in the priming effect data, which confirmed the hypothesis that increasing application rates of biochar to soil induce stronger negative priming on SOM mineralisation. The predicted size of recalcitrant biochar C pool varied from 98.8% (T1) to 99.9% (T3) of the total biochar C with respective mean residence time of 454 and 1539 years. It was concluded that increasing rates of biochar application to soil induce stronger negative priming effect on SOC due to the higher proportional quantity of biochar labile C and preferential utilisation of this easily available C source by micro-organisms. However, the size and long residence time of the recalcitrant C pool of biochar confirm its stability in soil, thus being considered an opportunity for C sequestration in OC-poor soils. Additionally, this study draws encouraging perspectives on the evaluation of sugarcane straw as a chemical feedstock and an alternative biofuel through pyrolysis, providing appreciable amounts of a renewable product with a great potential for carbon storage.

The aim of this study was to evaluate how distinct land uses can alter the trophic structure of fish communities in streams. For this purpose, nine streams under the influence of three distinct land uses (pasture, sugarcane, and natural cover) were evaluated. The structure and isotopic niche of the fish communities were investigated by calculating descriptive community-wide metrics based on stable isotopes of δ13C and δ15N. The largest isotopic niche was observed in fish communities in pasture streams, and the smallest in sugarcane streams. Pasture streams exhibited greater ranges of carbon sources exploited by fishes, higher trophic diversity, and lower trophic redundancy. In contrast, sugarcane streams had greater ranges of nitrogen exploited by fishes and showed the smaller trophic diversity, higher trophic redundancy, and uniformity. Sugarcane was also the only land use that exerted a negative influence on community isotopic niche width. Natural cover streams in turn, showed lower trophic uniformity and exhibited intermediate values for all remaining metrics. We conclude that fish communities residing in streams influenced by pastures displayed characteristics that led to greater trophic diversity, and fish communities influenced by sugarcane plantations were more negatively affected by this land use.

A revisão de limites e categorias de unidades de conservação têm se tornado comum na Amazônia brasileira. Entretanto, poucos estudos caracterizaram os eventos históricos e os papéis desempenhados por distintos atores regionais nos processos técnicos e políticos associados a estes eventos. Neste estudo foram investigados os eventos históricos subjacentes à reconfiguração de limites e categorias de dois Parques Estaduais no Estado do Amazonas. Foram registrados 56 eventos históricos e identificados 26 atores institucionais relevantes na gestão das duas unidades de conservação. A revisão dos limites e categoria se concretizou no Parque Estadual Rio Negro – Setor Sul. Por outro lado, as demandas sociais pouco estruturadas e um contexto desfavorável na política ambiental do Amazonas impediram a conclusão do processo no Parque Estadual do Rio Negro – Setor Norte. A revisão de limites e categorias pode ser uma estratégia válida de resolução parcial dos conflitos fundiários em unidades de conservação. Propostas desta natureza, no entanto, não devem ser banalizadas, mas baseadas em detalhadas análises técnico-científicas negociadas entre as comunidades locais, gestores e representantes políticos a fim de se evitar prejuízos na proteção da biodiversidade.

El déficit hídrico tiene un impacto negativo en el crecimiento y desarrollo de las plantas a través de alteraciones morfo-fisiológicas. Esta investigación se centró en la dinámica de los rasgos ecofisiológicos y arquitectura de dosel en dos cultivares de café, RUBI-MG1192 (Rubi) y IAPAR59 (I59), sensible y tolerante a la sequía, respectivamente. Los ensayos fueron durante dos años con tres tratamientos de riego, seis muestreos y 7-10 plantas por tratamiento. I59 retuvo sus hojas durante la sequía y demostró ser más isohidríco y plástico para rasgos de funcionamiento hídrico, con un ajuste precoz a la sequía. En contraste, Rubi tuvo desprendimiento de hojas y fue más anisohídrico y plástico para rasgos tardíos a la sequía. Se concluye que la aptitud de las plantas de café sometidas a eventos climáticos depende del ajuste entre las características morfo-fisiológicas y órgano-morfológicas. Estos rasgos deberán ser considerados en los programas de mejoramiento de café.

Made available in DSpace on 2019-10-06T15:31:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-15 Mixing N-fixing trees with eucalypts is an attractive option to improve the long-term soil N status in fast-growing plantations established in tropical soils. A randomized block design was replicated at four sites in Brazil to compare the biogeochemical cycles in mono-specific stands of Eucalyptus (100E) and Acacia mangium (100A) with mixed-species plantations in a proportion of 1:1 (50A50E). Our study aimed to assess the effects of introducing A. mangium trees in Eucalyptus plantations on atmospheric N 2 fixation, N cycling and soil organic matter stocks. Litterfall and soil N mineralization were measured over the last two years of the rotation (4–6 years after planting). Aboveground N accumulation in the trees and C and N stocks in the forest floor and in the top soil were intensively sampled at harvesting age. N 2 fixation rates were estimated using the natural abundance of 15 N as well as by the difference between total N stocks in 100A and 50A50E relative to 100E (accretion method). While the 15 N natural abundance method was unsuitable, the accretion method showed consistently across the four sites that atmospheric N fixation reached about 250 and 400 kg N ha −1 rotation −1 in 50A50E and 100A, respectively. Except at one site with high mortality, N contents within trees at harvesting were approximately 40% higher in 100A than in 100E. Mean N contents in litterfall and N mineralization rates were about 60% higher in 100A than in 100E, with intermediate values in 50A50E. The amounts of N in litterfall were much more dependent on soil N mineralization rates for acacia trees than for eucalypt trees. Soil C and N stocks were dependent on soil texture but not influenced by tree species. N budgets over a 6-year rotation were enhanced by about 65 kg N ha −1 yr −1 in 100A and 40 kg N ha −1 yr −1 in 50A50E relative to monospecific eucalypt plantations. Introducing N-fixing trees in eucalypt plantations might therefore contribute to reducing the need for mineral N fertilization in the long-term. USP ESALQ Forest Science Department UNESP Departamento de Solos e Recursos Ambientais Universidade Estadual Paulista ‘Júlio de Mesquita Filho’ CIRAD UMR Eco&Sols Eco&Sols INRA CIRAD IRD Montpellier SupAgro University of Montpellier USP CENA, Av. Centenário, 303 CENIBRA Coordenação de Pesquisa Florestal, 35196-972 Belo Oriente Department of Forest Science and Wood UFES, 29550-000 Jerônimo Monteiro UNESP Departamento de Solos e Recursos Ambientais Universidade Estadual Paulista ‘Júlio de Mesquita Filho’

The broad negative consequences of habitat degradation on biodiversity have been studied, but the complex effects of natural–agricultural landscape matrices remain poorly understood. Here we used stable carbon and nitrogen isotopes to detect changes in mammal resource and habitat use and trophic structure between preserved areas and human-modified landscapes (HMLs) in a biodiversity hot spot in South America. We classified mammals into trophic guilds and compared resource use (in terms of C(3)- and C(4)-derived carbon), isotopic niches, and trophic structure across the 2 systems. In HMLs, approximately one-third of individuals fed exclusively on items from the agricultural matrix (C(4)), while in preserved areas, ∼68% depended on forest remnant resources (C(3)). Herbivores, omnivores, and carnivores were the guilds that most incorporated C(4) carbon in HMLs. Frugivores maintained the same resource use between systems (C(3) resources), while insectivores showed no significant difference. All guilds in HMLs except insectivores presented larger isotopic niches than those in preserved areas. We observed a complex trophic structure in preserved areas, with increasing δ(15)N values from herbivores to insectivores and carnivores, differing from that in HMLs. This difference is partially explained by species loss and turnover and mainly by the behavioral plasticity of resilient species that use nitrogen-enriched food items. We concluded that the landscape cannot be seen as a habitat/nonhabitat dichotomy because the agricultural landscape matrix in HMLs provides mammal habitat and opportunities for food acquisition. Thus, favorable management of the agricultural matrix and slowing the conversion of forests to agriculture are important for conservation in this region.

Macrodactylus pumilio Burm. (Coleoptera: Scarabeidae) and Naupactus cervinus (Boh.) (Coleoptera: Curculionidae) are considered primary pests in citrus crops in Brazil, causing damage to plants and decreasing productivity. However, few studies investigate the ecology of these insects. In this context, the use of stable isotopes analysis (SIA) emerges as an alternative technique to conventional studies of behavioral ecology because it is faster and may explain feeding behavior based on the food source for each species. Field sampling and laboratory experiments were carried out to examine the changes of carbon and nitrogen stable isotope ratios (δ13C and δ15N) among pests and host plants (C3 citrus and C4 grasses), providing means to examine trophic interactions. Beetles were collected at the municipality of Gavião Peixoto, São Paulo State, identified and kept at 5 °C in saturated saline solution until the SIA. Two patterns for both species were found: δ13C value for N. cervinus was -23.6 ‰ and -13 ‰ for M. pumilio, indicating similarity between the results of δ13C of N. cervinus and citrus plants (-26 ‰) and dependence on grasses (-12 ‰) for M. pumilio individuals. The mean δ15N value was 4.3 and 5.8 ‰ for citrus plants and grass leaves, respectively, and the mean δ15N value was 4.4 ‰ for N. cervinus and 4.9 ‰ for M. pumilio. The results showed a higher affinity of N. cervinus for citrus roots since the larval stage compared with the alternative diet on M. pumilio.

This study investigated two estuaries on the northern coast of Brazil submitted to different anthropic activities. The main objective was to assess the use of oysters (Crassostrea gasar and Paxyodon ponderosus) and phytoplankton as bioindicators of environmental contamination. Water, sediments, phytoplankton and oysters were chemically analyzed by ICP-OES and ICP-MS. The source for metal bioaccumulation in oysters and phytoplankton was assessed using BSAF (Biota Sediment Accumulation Factor) and the isotropic relations of stable carbon ( δ 13 C and δ 15 N). The oyster-sediment BSAF showed bioaccumulation of Mn, Cu, Zn, Se, Sr, As, Cd and Ba, which was supported by the correlations of Fe, Mn, Cu, Zn, Se, Sr, Al, Ba and Pb with the isotopes ( δ 15 N and δ 13 C), which confirmed bioaccumulation as well as biodilution and biomagnification in oysters and phytoplankton. That reflects the efficiency of organisms in bioconcentrating metals and their capacity as bioindicators of contamination.

In this study, nitrogen stable isotope (δ(15) N) and total mercury (THg) analyses were conducted on algae, submersed and emergent macrophytes, shrubs and trees, Macrobrachium sp. and Paracheirodon axelrodi collected in three streams that drain a large interfluvial region in the middle Rio Negro, Amazonas State, Brazil. Samples were collected during different hydrological periods over 12 months in lower stream reaches and their headwaters; the latter being characterized by shallow, open-canopy swamps. Additionally, δ(15) N values and mercury concentrations of Paracheirodon simulans and Cichla spp. from the middle Rio Negro were analysed to demonstrate THg biomagnification in the food web. The highest mercury levels of P. axelrodi were found in small individuals, which were collected principally in the low water period. The log10 THg-δ(15) N relationship of vascular plants and algae, Macrobrachium sp., Paracheirodon spp. and Cichla spp. showed significant mercury biomagnification among trophic levels, with regression slopes of 0·15 and 0·25 for the entire food web and heterotrophs-only food web, respectively. The mean ± s.d. THg concentrations for Macrobrachium sp., P. axelrodi, P. simulans and Cichla spp. were 63·6 ± 23·7, 104·5 ± 40·0, 112·3 ± 31·4 and 418·5 ± 188·1 ng g(-1) wet mass, respectively. Elevated levels of mercury found in Paracheirodon spp. and top predators such as Cichla spp. in a remote area far from anthropogenic inputs provide evidence that high mercury concentrations occur naturally in Rio Negro aquatic food webs.

Made available in DSpace on 2018-11-26T16:27:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-03-15 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) CIRAD USP-COFECUB AGREENIUM (Plantrotem project) SOERE F-ORE-T Agence Nationale de la Recherche Adaptive strategies to improve tree water-use efficiency (WUE) are required to meet the global demand for wood in a future drier climate. A large-scale throughfall exclusion experiment was set up in Brazil to study the interaction between water status and potassium (K) or sodium (Na) availability on the ecophysiology of Eucalyptus grandis trees. This experiment focused primarily on the changes in aboveground net primary production, stand water use, phloem sap and leaf delta C-13, net CO2 assimilation and stomatal conductance. The correlations between these response variables were determined to gain insight into the factors controlling water-use efficiency in tropical eucalypt plantations. The intrinsic WUE in individual leaves (the ratio of net CO2 assimilation to stomatal conductance) was estimated at a very short time scale from the leaf gas exchange. Sap flow measurements were carried out to assess the WUE for stem wood production (the ratio of wood biomass increment to stand water use). Averaged over the two water supply regimes, the stemwood biomass 3 years after planting was 173% higher in trees fertilized with K and 79% higher in trees fertilized with Na than in trees with no K and Na addition. Excluding 37% of the throughfall reduced stemwood production only for trees fertilized with K. Total canopy transpiration between 1 and 3 years after planting increased from about 750 to 1300 mm y(-1) in response to K fertilization with a low influence of the water supply regime. K fertilization increased WUE for stemwood production by approx. 60% with or without throughfall exclusion. There was a strong positive correlation between phloem sap delta C-13 and short-term leaf-level intrinsic WUE. Whatever the water and nutrient supply regime, the gas exchange WUE estimates were not correlated with WUE for stemwood production. Phloem sap delta C-13 and leaf delta C-13 were therefore not valuable proxies of WUE for stemwood production. The allocation pattern in response to nutrient and water supply appeared to be a major driver of WUE for stemwood production. In areas with very deep tropical soils and annual rainfall

The aim of this study was to test if changes in land use alter the isotopic signature of fish species, promoting changes in the trophic position and food resource partitioning between these consumers. Three different systems were investigated: pasture streams (n = 3), streams in sugar cane plantations (n = 3) and reference streams (n = 3). Fish species Aspidoras fuscoguttatus, Astyanax altiparanae, Characidium zebra, Hisonotus piracanjuba and Knodus moenkhausii were selected, and their nitrogen and carbon isotopic compositions were estimated to assess changes in the trophic level and partitioning of food items consumed. The composition of δ(13) C (‰) only differed among the land use categories for A. altiparanae, H. piracanjuba and K. moenkhausii. Resource partitioning was different for all species, with changes in the sources or proportions they consumed in each land use category, but only A. altiparanae introduced new food sources in large quantity in altered land uses. It is important to note, however, that the results from the resource partitioning analysis are limited due to large overlapping of isotopic signatures between the analysed food resources. All fish species exhibited variation in δ(15) N (‰), with the highest values found in streams under sugar cane or pasture influence. Despite the variation in nitrogen isotopic values, only C. zebra and H. piracanjuba displayed changes in trophic level. Therefore, it is believed that the increase in the δ(15) N (‰) value of the individuals collected in streams under the influence of sugar cane or pasture was due to the greater influence of livestock dung and chemical and organic fertilizers. The results also highlight the importance of studying consumer species along with all forms of resources available at each location separately, because the signatures of these resources also vary within different land uses.

Leaves of 208 trees were collected for isotopic analysis together with wood from 36 tree boles and 18 samples of fine litter from a terra-firme forest located at Samuel Ecological Reserve, Rondonia State, in the southwestern Amazon region. The range of δ13C values in leaves was from −28 to −36‰, with an average (±1 SD) of −32.1 ± 1.5‰, which was more negative than the δ13C values of bole samples (−28.4 ± 2.0‰) and fine litter (−28.7 ± 2.0‰). These values are within the range found for tropical and subtropical forests. Pooling the δ13C values for leaf samples from trees of the same height gave averages which were positively correlated with plant height at a highly significant level, with a slope of 0.06 and an intercept of −33.3‰ and a correlation coefficient r2=0.70 (P