Evaluating environmental drivers of spatial variability in free-living nematode assemblages along the Portuguese margin

Understanding processes responsible for shaping biodiversity patterns on continental margins is an important requirement for comprehending anthropogenic impacts in these environments and further management of biodiversity. Continental margins perform crucial functions linked to key ecological processes which are mainly structured by surface primary productivity and particulate organic matter flux to the seafloor, but also by heterogeneity in seafloor characteristics. However, to what extent these processes control local and regional biodiversity remains unclear. In this study, two isobathic parallel transects located at the shelf break (300-400 m) and upper slope (1000 m) of the western Iberian margin were used to test how food input and sediment heterogeneity affect nematode diversity independently from the spatial factors geographical distance and water depth. We also examined the potential role of connectedness between both depth transects through molecular phylogenetic analyses. Regional generic diversity and turnover were investigated at three levels: within a station, between stations from the same depth transect, and between transects. High variability in food availability and high sediment heterogeneity at the shelf-break transect were directly linked to high diversity within stations and higher variation in community structure across stations compared to the upper slope transect. Contrastingly, environmental factors (food availability and sediment) did not vary significantly between stations located at the upper slope, and this lack of differences were also reflected in a low community turnover between these deeper stations. Finally, differences in nematode communities between both transects were more pronounced than differences within each of the isobathic transects, but these changes were paralleled by the previously mentioned environmental changes. These results suggest that changes in community structure are mainly dictated by environmental factors rather than spatial differences at the western Iberian margin. Furthermore, phylogenetic relationships revealed no evidence for depth-endemic lineages, indicating regular species interchanges across different depths

Calcificação do tendão do músculo supra-espinhoso em cão da raça Rottweiler

O artigo não apresenta resumo

Abyssal plain faunal carbon flows remain depressed 26 years after a simulated deep-sea mining disturbance

Future deep-sea mining for polymetallic nodules in abyssal plains will negatively impact the benthic ecosystem, but it is largely unclear whether this ecosystem will be able to recover from mining disturbance and if so, to what extent and at what timescale. During the “DISturbance and reCOLonization” (DISCOL) experiment, a total of 22% of the seafloor within a 10.8 km2 circular area of the nodulerich seafloor in the Peru Basin (SE Pacific) was ploughed in 1989 to bury nodules and mix the surface sediment. This area was revisited 0.1, 0.5, 3, 7, and 26 years after the disturbance to assess macrofauna, invertebrate megafauna and fish density and diversity. We used this unique abyssal faunal time series to develop carbon-based food web models for each point in the time series using the linear inverse modeling approach for sediments subjected to two disturbance levels: (1) outside the plough tracks; not directly disturbed by plough, but probably suffered from additional sedimentation; and (2) inside the plough tracks. Total faunal carbon stock was always higher outside plough tracks compared with inside plough tracks. After 26 years, the carbon stock inside the plough tracks was 54% of the carbon stock outside plough tracks. Deposit feeders were least affected by the disturbance, with modeled respiration, external predation, and excretion rates being reduced by only 2.6% inside plough tracks compared with outside plough tracks after 26 years. In contrast, the respiration rate of filter and suspension feeders was 79.5% lower in the plough tracks after 26 years. The “total system throughput” (T ..), i.e., the total sum of modeled carbon flows in the food web, was higher throughout the time series outside plough tracks compared with the corresponding inside plough tracks area and was lowest inside plough tracks directly after the disturbance (8.63 103 1.58 105 mmol Cm2 d1). Even 26 years after the DISCOL disturbance, the discrepancy of T .. between outside and inside plough tracks was still 56 %. Hence, C cycling within the faunal compartments of an abyssal plain ecosystem remains reduced 26 years after physical disturbance, and a longer period is required for the system to recover from such a small-scale sediment disturbance experiment.publishe

Importância de caracteres morfoagronômicos no guaranazeiro por componentes principais.

A análise da importância de caracteres tem permitido determinar caracteres de interesse de acordo com sua contribuição para a diversidade genética, permitindo ao melhorista concentrar esforços nos caracteres que foram mais importantes, diminuindo os custos de suas pesquisas. O objetivo deste trabalho é verificar as implicações da utilização da análise de importância de caracteres para eliminação destes no cálculo da distância genética entre clones de guaranazeiro. Foram avaliados 32 clones de guaranazeiro em três experimentos em blocos casualizados, com duas repetições e parcelas compostas por três plantas, em espaçamento 5x5 metros. As variáveis avaliadas foram produção, número de ramos e folhas por planta, comprimento do ramo e diâmetro do ramo. Os dados foram submetidos à análise de variância, cálculo da distância euclidiana média padronizada, calculada como medida da importância relativa dos caracteres estimada por meio da participação dos componentes relativos a cada característica, no total da dissimilaridade observada, e para o agrupamento dos clones, utilizou-se o método de Tocher. A produção é o caráter mais importante para a diversidade genética, seguida do número de ramos. O número de folhas é o caráter menos importante para a diversidade genética podendo ser descartado das avaliações seletivas com clones de guaranazeir

Biologia de Heliothis virescens (Lepidoptera: Noctuidae) em folhas de soja (Glycine max).

Este estudo teve como objetivo determinar a influencia na biologia de Heliothis virescens do consumo exclusivo de folhas e a capacidade de consumo foliar.Pôster - graduação

Resistência de cultivares e linhagens avançadas de arroz irrigado à queima da bainha em casa de vegetação e no campo.

No presente estudo foi feita a comparação do grau de resistência de linhagens e cultivares de arroz avaliadas em casa de vegetação e no campo em ensaios realizados em Formoso do Araguaia no Tocantins e em Goianira, Goiás