Desenvolvimento larvar de Brachidontes solisianus: com notas sobre as diferenças do seu sistema ligamentar quando comparado ao de Perna perna

This work, which is part of a study program on meroplankton larvae, aims to gain more in-depth knowledge about planktonic larvae. This study began with the mollusk Brachidontes solisianus (Bivalvia - Mytilidae), which is abundant on the rocky shores of the Cabo Frio region (state of Rio de Janeiro, Brazil). Brachidontes solisianus larvae were grown under controlled conditions for a period of 26 days and were fed with Isochrysis galbana and Tetraselmis chui. The temperature was kept at 26 °C and the saltiness at 28 . Images of the larvae were taken daily with a light camera and measured with a micrometric lens until settlement occurred. The average size of the first D-shaped veliger stage was 90 µm in length and 70 µm in height, while the size in the last stage before settlement (pediveliger) was 273 µm in length and 257 µm in height. The comparative study of the hinge system involved the most abundant intertidal species of the study area: Brachidontes solisianus and Perna perna. The B. solisianus species were found to have more visible denticles at the extremities of the provinculum, whereas the denticles of the P. perna species occur along the entire provinculum.Este trabalho faz parte de um programa de estudo sobre larvas meroplanctônicas que tem como objetivo o reconhecimento mais preciso das larvas no plâncton. Este estudo foi iniciado com a espécie Brachidontes solisianus (Bivalvia - Mytilidae) que é muito abundante nos costões rochosos da região de Cabo Frio. O desenvolvimento larvar foi realizado sob condições controladas durante 26 dias. A alimentação foi feita com Isochrysis galbana e Tetraselmis chui. A temperatura e a salinidade foram mantidas a 26° C e 28 , respectivamente. Diariamente, as larvas foram desenhadas em câmara clara e medidas com ocular micrométrica até a fixação. A primeira fase de véliger em forma de "D" ou Prodissoconcha I, mediu em média, 90 µm de comprimento por 70 µm de altura e a última, antes da fase de fixação (Pedivéliger), mediu 273 µm de comprimento e 257 µm de altura. No estudo comparativo das charneiras, duas espécies foram consideradas: Brachidontes solisianus e Perna perna. Observou-se que a espécie B. solisianus apresenta dentes mais evidentes nas extremidades do provinculum, enquanto na espécie P. perna aparecem ao longo de todo o provinculum

The EChO science case

The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune—all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10−4 relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 μm with a goal of covering from 0.4 to 16 μm. Only modest spectral resolving power is needed, with R ~ 300 for wavelengths less than 5 μm and R ~ 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m2 is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m2 telescope, diffraction limited at 3 μm has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300–3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright “benchmark” cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO’s launch and enable the atmospheric characterisation of hundreds of planets

Spatial variability in the icthyoplankton structure of a subtropicalhypersaline lagoon

Abstract The Lagoa de Araruama is a hypersaline ecosystem inhabited by distinct fish species, either permanently or during their reproductive season. Over recent years, some significant environmental changes have been observed in this ecosystem related to the sewage runoff, as salinity decrease (from 64 to 41 psu during the last 40 years) and nutrients increase. As both changes are thought to affect the ichthyoplankton assemblage, the present study aimed to evaluate all the potential relationships between salinity disruption and fish larvae distribution. Ichtyoplankton samples were collected monthly from January 2010 to March 2011 at eight sites in Araruama Lagoon by means of a WP2 plankton net equipped with a flowmeter. During this period, low egg densities were coincident with high salinity regions, suggesting that adults are avoiding to release their eggs under less favorable environmental conditions to the larvae. The uneven distribution of eggs and larvae inside the lagoon, as revealed by both spatial and temporal analyses lead us to suggest that changes in salinity have influenced the reproductive rhythms of those fish species that depend upon the Lagoa de Araruama

Complementarity in the adoption of traceability of beef cattle in Brazil

Abstract Complementarity is an interesting approach to explain technology adoption. Taking account the other activities the farm performs in its production strategy can help understanding the decision on the adoption of new agricultural technology. This paper aims to evidence the existence of synergic effect resulting from the joint adoption of feedlot and traceability certification of beef cattle in Brazil. A sample of 84 beef cattle farms provided data to test hypotheses by using an OLS regression model. A measure of performance – revenue – is regressed on variables representing both isolated and joint adoption of capital-intensive production system and traceability. The results suggest the existence of synergic effect when joint adoption takes place. Joint adoption is influenced by a set of management practices, such as forward contracts, training of employees and zootechnical performance control, which are shared by both capital-intensive production systems and traceability

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge, 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 organism 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 neglected 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 lost