Inclinação de Assentamento de Larvas e Adultos do Coral Recifal Favia Gravida em Recifes de Porto Seguro, Bahia, Brasil

A successful reproduction is the first step in coral larvae recruitment on the reefs. Substrate types, as well as its orientation may affect coral recruitment, growth and survival rates. The current study was made at Porto Seguro, BA, Brasil, and aimed to observe planulation pattern, verifying the settlement preference of larvae on three different substrate slopes - horizontal, vertical and inclinated (45o) and evaluate the slope preference of Favia gravida adult colonies in different reefs of Porto Seguro, BA. Adult colonies were taken to aquariums and observed until planulation. Recently released larvae were transferred for aquariums with recruitment plates. These plates were examined after the 21st day of planulation. Porto Seguro most common reef types were sampled regarding adults occurrence: “coastal reefs”, the top of a patch reef or a reef flat, and the internal wall of a large lagoon inside Recife de Fora. Colonies slope were measured using a graduated arc and a float or weight (for negative positioned colonies) placed at the base of each colony, comprising a total of 540 colonies, 180 in each reef sampled. The larvae did not present a preference for substrate slope. Since adult colonies were commonly found at slightly steep upper surfaces, it is suggested that differential mortality may have happened with larvae in other surfaces. As Favia gravida larvae did not present strict slope preferences, and based on the knowledge that adults tend to occur at moderate steep surfaces, the results suggest this is the most suitable orientation for recruit introduction in Porto Seguro reefs in rehabilitation activities of degraded environmental, to certify most recruits survivorship in long term.O sucesso na reprodução é o primeiro passo para o recrutamento de corais nos recifes. O tipo de substrato, bem como a sua orientação, pode afetar o recrutamento, crescimento, e taxas de sobrevivência de corais. O presente estudo teve como objetivos observar o padrão de planulação, verificar a preferência de assentamento de larvas em placas com diferentes inclinações - horizontal, vertical e inclinada (45o) e analisar a inclinação preferencial de colônias adultas do coral Favia gravida em diferentes recifes de Porto Seguro, BA. Colônias adultas foram mantidas em aquários e acompanhadas até a planulação. As larvas recém liberadas foram transferidas para aquários com placas de recrutamento. Estas foram triadas a partir do 21o dia após a última adição de larvas. Os principais tipos recifais encontrados em Porto Seguro foram amostrados: recifes costeiros, o topo de um “cabeço”, e a borda interna de uma das piscinas naturais do Recife de Fora. A inclinação das colônias foi determinada com a ajuda de um transferidor e uma bóia ou peso (para inclinações negativas) posicionando-o junto à base da colônia, totalizando na medição de 540 colônias, 180 por local amostrado. As larvas não apresentaram preferência por uma determinada inclinação durante o assentamento. Como as colônias adultas de Favia gravida foram encontradas com maior freqüência em superfícies superiores e ligeiramente inclinadas no substrato recifal, sugere-se que pode haver mortalidade diferencial das larvas assentadas em outras posições. Não havendo restrição de inclinações para assentamento das larvas de F. gravida e sabendo que adultos da mesma espécie tendem a ocorrer em superfícies inclinadas superiores, os resultados sugerem que esta seja a orientação mais adequada para implantação de recrutas nos recifes de Porto Seguro em atividades de recuperação de ambientes degradados, garantindo assim, uma maior sobrevivência dos recrutas a longo prazo

Selective factors involved in oil flotation isolation of black yeasts from the environment

The oil flotation isolation technique has been successfully applied to recover chaetothyrialean black yeasts and relatives from the environment. The selective mechanisms playing a role in isolation are unknown. The fungi concerned are supposed to occupy specialized microniches in nature, taking advantage of (1) oligotrophism. Mineral oil as a main selective agent may be based on (2) hydrophobicity or on (3) assimilation. All three hypotheses are tested in this paper. Results show that cell wall hydrophobicity is unlikely to be a selective factor. Incubation under poor nutrient conditions provides competitive advantage for black yeasts, especially for Exophiala strains, which are subsequently enriched by mineral oil which enhances growth in this group of fungi. Incubation under mineral media and mineral oil can be used as selective factor

Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum

We report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at $\lg(E/{\rm eV})=18.5-19.0$ differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass $A > 4$. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report Numbe