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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.

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.

This study aimed to evaluate if the presence of pollutants promotes changes in feeding habits of fish species from different trophic guilds: the detritivorous species, Hypostomus francisci, and the piscivorous, Hoplias intermedius. Both species were sampled at 12 sites (with different degrees of pollution) in the Rio das Velhas basin, which is heavily polluted by domestic and industrial sewage from the Metropolitan Region of Belo Horizonte (MRBH). Stable isotope analyses of carbon (δ13C) and nitrogen (δ15N) of fish tissue and the main food resources were performed. Fishes from both trophic guilds altered their diets in degraded environments, but the detritivorous species showed greater trophic plasticity. The isotopic niche of both trophic guilds was broadest in unpolluted sites and more δ15N enriched in polluted regions. The detritivorous species presented high niche-breadth in unpolluted sites, probably due to the greater variety of resources consumed. In addition, the δ15N of the detritivorous was more enriched than the piscivorous species in polluted sites. In conclusion, fishes from both trophic guilds presented similar isotopic responses to environmental pollution. However, the detritivorous species was more sensitive to these alterations and therefore, is likely a better indicator of environmental condition than the piscivorous. RESUMO Este estudo teve como objetivo avaliar se a presença de poluentes promove mudanças nos hábitos alimentares de espécies de peixes de diferentes guildas tróficas: a espécie detritívora, Hypostomus francisci, e a piscívora, Hoplias intermedius. Ambas espécies foram amostradas em 12 locais (com diferentes níveis de poluição) na bacia do Rio das Velhas, que é altamente poluída por esgoto doméstico e industrial da Região Metropolitana de Belo Horizonte (RMBH). Foram realizadas análises de isótopos estáveis de carbono (δ13C) e nitrogênio (δ15N) dos tecidos dos peixes e dos principais recursos alimentares. Espécies de ambas guildas tróficas alteraram suas dietas em ambientes degradados, mas a espécie detritívora apresentou maior plasticidade trófica. O nicho isotópico de ambas as espécies foi mais amplo em locais menos perturbados e mais enriquecido em δ15N em regiões poluídas. A espécie detritívora apresentou grande amplitude em seu nicho isotópico em locais menos perturbados, provavelmente devido à maior variedade de recursos consumidos. Além disso, o δ15N da espécie detritívora foi mais enriquecido que a espécie piscívora em locais poluídos. Em conclusão, ambas as espécies apresentaram respostas isotópicas semelhantes à poluição ambiental. No entanto, a espécie detritívora foi mais sensível a essas alterações e, portanto, é provavelmente uma melhor indicadora de condição ambiental do que a espécie piscívora.

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.

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 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.

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

Made available in DSpace on 2018-12-11T17:27:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Tropical rainforests support the greatest diversity of small mammals in the world, yet we have little understanding about the mechanisms that promote the coexistence of species. Diet partitioning can favor coexistence by lessening competition, and interspecific differences in body size and habitat use are usually proposed to be associated with trophic divergence. However, the use of classic dietary methods (e.g. stomach contents) is challenging in small mammals, particularly in community-level studies, thus we used stable isotopes (δ13C and δ15N) to infer about trophic niche. We investigated i) how trophic niche is partitioned among rodent and marsupial species in three Atlantic forest sites and ii) if interspecific body size and locomotor habit inequalities can constitute mechanisms underlying the isotopic niche partitioning. We found that rodents occupied a broad isotopic niche space with species distributed in different trophic levels and relying on diverse basal carbon sources (C3 and C4 plants). Surprisingly, on the other hand, marsupials showed a narrow isotopic niche, both in δ13C and δ15N dimensions, which is partially overlapped with rodents, contradicting their description as omnivores and generalists proposed classic dietary studies. Although body mass differences did not explained the divergence in isotopic values among species, groups of species with different locomotor habit presented clear differences in the position of the isotopic niche space, indicating that the use of different forest strata can favor trophic niche partitioning in small mammals communities. We suggest that anthropogenic impacts, such as habitat modification (logging, harvesting), can simplify the vertical structure of ecosystems and collapse the diversity of basal resources, which might affect negatively small mammals communities in Atlantic forests. Departamento de Ecologia Universidade Estadual Paulista (UNESP), C.P. 199 Casa da Floresta Assessoria Ambiental Ltda. CENA Universidade de São Paulo Programa de Pósgraduação em Ecologia e Biodiversidade Universidade Estadual Paulista (UNESP), C.P. 199 Departamento de Ecologia Universidade Estadual Paulista (UNESP), C.P. 199 Programa de Pósgraduação em Ecologia e Biodiversidade Universidade Estadual Paulista (UNESP), C.P. 199

Made available in DSpace on 2022-04-28T19:03:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-08-11 Potassium (K) is an important limiting factor of tree growth, but little is known of the effects of K supply on the long-distance transport of photosynthetic carbon (C) in the phloem and of the interaction between K fertilization and drought. We pulse-labelled 2-year-old Eucalyptus grandis L. trees grown in a field trial combining K fertilization (+K and -K) and throughfall exclusion (+W and -W), and we estimated the velocity of C transfer by comparing time lags between the uptake of 13CO2 and its recovery in trunk CO2 efflux recorded at different heights. We also analysed the dynamics of the labelled photosynthates recovered in the foliage and in the phloem sap (inner bark extract). The mean residence time of labelled C in the foliage was short (21-31 h). The time series of 13C in excess in the foliage was affected by the level of fertilization, whereas the effect of throughfall exclusion was not significant. The velocity of C transfer in the trunk (0.20-0.82mh-1) was twice as high in +K trees than in -K trees, with no significant effect of throughfall exclusion except for one +K-W tree labelled in the middle of the drought season that was exposed to a more pronounced water stress (midday leaf water potential of -2.2MPa). Our results suggest that besides reductions in photosynthetic C supply and in C demand by sink organs, the lower velocity under K deficiency is due to a lower cross-sectional area of the sieve tubes, whereas an increase in phloem sap viscosity is more likely limiting phloem transport under drought. In all treatments, 10 times less 13C was recovered in inner bark extracts at the bottom of the trunk when compared with the base of the crown, suggesting that a large part of the labelled assimilates has been exported out of the phloem and replaced by unlabelled C. This supports the 'leakage-retrieval mechanism' that may play a role in maintaining the pressure gradient between source and sink organs required to sustain high velocity of phloem transport in tall trees. UMR 1137 Ecologie et Ecophysiologie Forestières Facult des Sciences Universit de Lorraine INRA UMR 1137 Ecologie et Ecophysiologie Forestières Centre de Nancy CIRAD UMR Ecoandsols Ecologie Fonctionnelle and Biogochimie des Sols and Agro-cosystèmes Embrapa Meio Ambiente Universidade Estadual de São Paulo Departamento de Ciências Florestais ESALQ Universidade de São Paulo ESALQ Laboratory of Forest Utilization Department of Forest and Biomaterial Science Graduate School of Agriculture Kyoto University Centro de Energia Nuclear Na Agricultura Universidade de São Paulo Departamento de Ciências Atmosfricas IAG Universidade de São Paulo ESALQ Universidade Estadual de São Paulo

In studies of ant-plant mutualisms, the role that ants play in increasing the growth rates of their plant partners is potentially a key beneficial service. In the field, we measured the growth of Cecropia glaziovii saplings and compared individuals that were naturally colonized by Azteca muelleri ants with uncolonized plants in different seasons (wet and dry). We also measured light availability as well as attributes that could be influenced by the presence of Azteca colonies, such as herbivory, leaf nutrients (total nitrogen and δ15N), and investments in defense (total phenolics and leaf mass per area). We found that colonized plants grew faster than uncolonized plants and experienced a lower level of herbivory in both the wet and dry seasons. Colonized plants had higher nitrogen content than uncolonized plants, although the δ15N, light environment, total phenolics and leaf mass per area, did not differ between colonized and uncolonized plants. Since colonized and uncolonized plants did not differ in the direct defenses that we evaluated, yet herbivory was lower in colonized plants, we conclude that biotic defenses were the most effective protection against herbivores in our system. This result supports the hypothesis that protection provided by ants is an important factor promoting plant growth. Since C. glaziovii is widely distributed among a variety of forests and ecotones, and since we demonstrated a strong relationship with their ant partners, this system can be useful for comparative studies of ant-plant interactions in different habitats. Also, given this study was carried out near the transition to the subtropics, these results help generalize the geographic distribution of this mutualism and may shed light on the persistence of the interactions in the face of climate change. © 2015 Oliveira et al., Financial support was provided by a grant from the Brazilian National Council for Scientific and Technological Development (CNPq – proc. #479576/2011-4) coordinated by RIC. KNO was supported by a national PhD fellowship from Foundation of Support to the Research of Minas Gerais (FAPEMIG) and an international PhD sandwich fellowship from CAPES– Processo n° 99999.000258/2014-08. PDC and TAK’s participation in this research was supported by NSF DEB-0444590.

It is well recognized that assemblage structure of stream macroinvertebrates changes with alterations in catchment or local land use. Our objective was to understand how the trophic ecology of benthic macroinvertebrate assemblages responds to land use changes in tropical streams. We used the isotope methodology to assess how energy flow and trophic relations among macroinvertebrates were affected in environments affected by different land uses (natural cover, pasture, sugar cane plantation). Macroinvertebrates were sampled and categorized into functional feeding groups, and available trophic resources were sampled and evaluated for the isotopic composition of 13C and 15N along streams located in the Cerrado (neotropical savanna). Streams altered by pasture or sugar cane had wider and more overlapped trophic niches, which corresponded to more generalist feeding habits. In contrast, trophic groups in streams with native vegetation had narrower trophic niches with smaller overlaps, suggesting greater specialization. Pasture sites had greater ranges of resources exploited, indicating higher trophic diversity than sites with natural cover and sugar cane plantation. We conclude that agricultural land uses appears to alter the food base and shift macroinvertebrate assemblages towards more generalist feeding behaviors and greater overlap of the trophic niches.

Background and aims Eucalyptus plantations cover 20 million hectares on highly weathered soils. Large amounts of nitrogen (N) exported during harvesting lead to concerns about their sustainability. Our goal was to assess the potential of introducing A. mangium trees in highly productive Eucalyptus plantations to enhance soil organic matter stocks and N availability. Methods A randomized block design was set up in a Brazilian Ferralsol soil to assess the effects of mono-specific Eucalyptus grandis (100E) and Acacia mangium (100A) stands and mixed plantations (50A:50E)on soil organic matter stocks and net N mineralization. Results A 6-year rotation of mono-specific A. mangium plantations led to carbon (C) and N stocks in the forest floor that were 44% lower and 86% higher than in pure E. grandis stands, respectively. Carbon and N stocks were not significantly different between the three treatments in the 0-15 cm soil layer. Field incubations conducted every 4 weeks for the two last years of the rotation estimated net soil N mineralization in 100A and 100E at 124 and 64 kg ha(-1) yr(-1), respectively. Nitrogen inputs to soil with litterfall were of the same order as net N mineralization. Conclusions Acacia mangium trees largely increased the turnover rate of N in the topsoil. Introducing A. mangium trees might improve mineral N availability in soils where commercial Eucalyptus plantations have been managed for a long time.