Ecologia de insetos aquáticos em córregos do Cerrado: do nicho hutchinsoniano ao distúrbio intermediário

A região do Cerrado é o segundo maior bioma brasileiro abrangendo cerca de 22% do território nacional. Devido a facilidades que o mesmo apresenta para manejo e cultivo do solo, o Cerrado vem sofrendo uma intensa mudança na sua paisagem, aumentando o impacto em todos os seus sistemas naturais. Através de uma coleta sistematizada em 101 córregos na região da bacia do rio das Almas, centro goiano, pode ser observado como essa mudança na paisagem altera a comunidade de insetos aquáticos bentônicos. Em um primeiro momento não observamos mudanças no número de gêneros para diferentes tamanhos de rios. O aumento do impacto, principalmente na região ripária, leva a uma redução no número de gêneros de Ephemeroptera, Plecoptera e Trichoptera. Comunidades em localidades impactadas são compostos de subconjuntos das comunidades em locais preservados, apresentando um padrão de aninhamento. Apesar da redução do número de gêneros em locais impactados a riqueza esperada pelo somatório das probabilidades de ocorrência dos gêneros em um determinado valor de integridade se mostra maior tanto em locais conservados como degradados. Assim a taxa de substituição de gêneros tende a ser maior em localidades muito impactadas e bem preservadas. A matriz ambiental no Cerrado é composta em grande parte por áreas já impactadas, o que explicaria essa grande quantidade de gêneros que vivem em locais degradados, através do simples efeito de área. Por último comparamos os resultados de dois índices usados para monitoramento ecológico de córregos, que visam observar tipos de impactos diferentes no ambiente. Não houve relação entre o Índice de Integridade de Habitat e um índice que mensura teor de poluição na água (BMWP’), indicando que existe a necessidade do uso dos dois em conjunto para um monitoramento efetivo

Mosquitos (Diptera, Culicidae) habitando tanques foliares de Guzmania brasiliensis Ule (Bromeliaceae) na Amazônia Central, Brasil

Mosquitoes in the family Culicidae develop their immature forms in different environments depending on various circumstances. This study represents the first contribution to the ecological knowledge of culicids living in the bromeliad G. brasiliensis. The objectives of the study were to compare the Culicidae fauna of bromeliads in two seasonal periods, analyzing their abundance, richness and the influence of pH, conductivity and water volume, on the populations. Sampling was done at Reserva Adolpho Ducke, Manaus, Amazonas, Brazil between 2003 and 2005. Six samplings were done in the rainy season and six in the dry season. On each sampling day, six terrestrial and six epiphytic bromeliads, totaling 144 sampling units, were retrieved. A total of 444 immature mosquitoes were collected, distributed in the following species: Culex (Microculex) stonei Lane & Whitman, Culex (Microculex) chryselatus Dyar & Knab, Culex (Microculex) sp., Wyeomyia (Hystatomyia) autocratica Dyar & Knab and Wyeomyia (Hystatomyia) splendida Bonne-Wepster & Bonne. The relationship between abundance of Culicidae and sampling period was not significant, although abundance was higher in the dry period. There were significant correlations between water volume and the abundance (p = 0.003) and richness (p = 0.001) of culicids. The pH was positively related to the occurrence of the species Wy. autocratica (p= 0.010) and Wy. splendida (p= 0.006), demonstrating the influence of this factor in the structuring of bromeliadinhabiting communities

Niche-Relationships Within and Among Intertidal Reef Fish Species

Niche-related processes (e.g., density or niche-breadth compensation and competition) are fundamental to a broad understanding of community ecology and ecosystem functioning. Most evidences of competition are from controlled indoor trials with few species, and it remains a challenge to estimate competition among multiple species in the field. Here, we analyze stable isotopes and distributional data from 51 fish taxa in six locations in the southwestern Atlantic to predict intraspecific trophic pressure (ITP) and the potential competitive strength among species in a trophic-based framework. We used two proxies built upon 2-dimensional isotopic space (δ13C vs. δ15N), its predicted overlap, and fish density to calculate winner and loser taxa in potential paired interspecific competitive interactions. The intraspecific proxy indicated that cryptobenthic fishes are under high among-individual trophic pressure (high densities and small niche sizes). Also, cryptobenthic behavior together with feeding specialization and extremely small-sizes were the most important traits related to low success in interspecific simulations. Although cryptobenthic fishes face strong competitive pressures, there are some known inherent trade-offs to cryptobenthic life such as trophic and habitat use specializations. These seem to compensate and ensure coexistence among cryptobenthic fishes and non-cryptobenthic species. Habitat loss/degradation via urbanization, invasive species and climate-change-driven sea-level rise can reduce the suitability of habitat and increase competition on cryptobenthic species, especially in shallow reefs and intertidal shores

Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 $< p_{\rm{T}, assoc} < p_{\rm{T}, trig} <$ 5.0 GeV/$c$ is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range $|\eta|<0.9$. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

Multi-particle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider

Measurements of multi-particle azimuthal correlations (cumulants) for charged particles in p-Pb and Pb-Pb collisions are presented. They help address the question of whether there is evidence for global, flow-like, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a $|\Delta \eta|$ gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high-multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of $v_{2}\{4\}$ to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find $v_{2}\{4\} \simeq v_{2}\{6\}\neq 0$ which is indicative of a Bessel-Gaussian function for the $v_{2}$ distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a $|\Delta\eta| > 1.4$ gap is placed.Comment: 25 pages, 11 captioned figures, 3 tables, authors from page 20, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/87

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

K0S and Λ production in Pb-Pb collisions at sNN−−−−√=2.76 TeV

The ALICE measurement of K0S and Λ production at midrapidity in Pb-Pb collisions at sNN−−−√=2.76  TeV is presented. The transverse momentum (pT) spectra are shown for several collision centrality intervals and in the pT range from 0.4  GeV/c (0.6  GeV/c for Λ) to 12  GeV/c. The pT dependence of the Λ/K0S ratios exhibits maxima in the vicinity of 3  GeV/c, and the positions of the maxima shift towards higher pT with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate pT is not observed in pp interactions at s√=0.9  TeV and at s√=7  TeV. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured pT spectra above 2  GeV/c progressively decouple from hydrodynamical-model calculations. For higher values of pT, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the pT dependence of the Λ/K0S ratio