Influence of filtration and glucose amendment on bacterial growth rate at different tidal conditions in the Minho Estuary River (NW Portugal)

Bacterioplankton abundance, biomass and growth rates were studied in theMinho Estuary River (NW Portugal). The influence of tidal conditions, glucose amendment, and the filtration process on total bacterial abundance, total and faecal coliforms, as well as faecal streptococci, were evaluated in laboratory incubation experiments. Physical and chemical conditions, as well as bacterial abundance in this estuary were found to be typical for oligo-mesotrophic coastal ecosystems. Bacterial abundance was higher at high tide, probably due to hydrodynamics and resuspension of bacteria from sediments. In contrast, a significant decrease of bacterial indicators of faecal pollution at high tide was probably the result of various causes, such as the decrease of continental and agricultural land run-off effect by dilution, and/or increase in the abundance of potential specific predators. Thus, drastic changes were induced at high tide that led to a lack of bacterial growth and the net disappearance of most of the bacterial populations. Glucose amendment, at used concentration, was not found to stimulate bacterial growth, which instead could be limited by inorganic nutrients.La abundancia, la biomasa y las tasas de crecimiento de bacterioplancton fueron estudiadas en el estuario del río Miño (NW Portugal). La influencia de condiciones de marea, de la adición de glucosa y del proceso de filtración en la abundancia total de bacterias, coliformes totales y coliformes fecales, así como de estreptococos fecales, fue evaluada en experimentos de incubación en laboratorio. Las condiciones físicas y quíımicas, así como la abundancia bacteriana encontradas en este estuario son típicas para los ecosistemas costeros oligo-mesotroficos. La abundancia bacteriana fue más alta en la alta marea, probablemente debido a la hidrodinámica y a la resuspensión de bacterias de los sedimentos. En contraste, la disminución significativa de los indicadores bacterianos de la contaminación fecal en la alta marea resultó probablemente de varias causas, tales como la disminución del efecto de vertido de la región continental y agrícola por la dilución, y/o aumento en la abundancia de depredadores específicos potenciales. En resultado, cambios drásticos fueron inducidos en la alta marea originando la ausencia de crecimiento bacteriano y la desaparición neta de la mayoría de las poblaciones bacterianas. La adición de la glucosa, en la concentración usada, no estimuló el crecimiento bacteriano, que se podría limitar por los alimentos inorgánicos

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A Diagnostic Survey of Aborted Equine Fetuses and Stillborn Premature Foals in Denmark

Background: Loss of pregnancy in mares can have many different causes, including both infectious and non-infectious conditions. Extrapolation of findings from other studies is often uncertain as the significance of each cause varies across regions. Causes of pregnancy loss in mares have never been thoroughly studied in Denmark, so a prospective cross-sectional cohort study targeting the entire Danish population of pregnant mares was performed over a period of 13 months to obtain knowledge of the significance of individual causes. Fifty aborted or prematurely delivered stillborn fetuses were submitted for necropsy and examined by a panel of diagnostic laboratory methods.Results: Overall, a cause of fetal loss was established for 72% of the examined cases. Most cases (62%) were lost due to a non-infectious cause, of which obstruction of the feto-placental blood circulation due to severe torsion of the umbilical cord was most prevalent. Pregnancy loss due to a variety of opportunistic bacteria, including bacteria not previously associated with abortion in mares, accounted for 12%, while equid alphaherpesvirus (EHV) type 1 was the cause of pregnancy loss in 8% of the cases. EHV type 4 and Chlamydiaceae species were identified in some cases, but not regarded as the cause of fetal loss.Conclusion: Umbilical cord torsion was found to be the most prevalent cause of fetal loss in Danish mares, while infectious causes such as EHV type 1 and streptococci only accounted for a minor proportion of the losses. The study highlights the need for defined criteria for establishing an abortion diagnosis in mares, particularly in relation to EHV types 1 and 4

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Artisanal fishing characterization and spatio-temporal occurrence of marine shrimp (Crustacea, Decapoda, Penaeidae) in the littoral of Lucena, Paraíba, Brazil

The present study distinguishes types of fishing activities. It records the most economically exploited shrimps in the municipality of Lucena, Paraíba, Xiphopenaeus kroyeri (“espigudo”), and Penaeus schmitti (white shrimp). From October 2014 to October 2015, samples containing 700 gr of shrimp were collected at three sites of artisanal fishing. Data on temperature, ammonium, nitrate, nitrite, chlorophyll-a, salinity, pH, and dissolved oxygen were recorded.  Two different shrimp species are commercially used in the region, of 2,628 sampled individuals, X. kroyeri predominated, with 1,957 individuals, followed by P. schmitti, with 671 individuals. At localities 1 (in Lucena beach) and 2 (Fagundes beach) both species were present, the X. kroyeri being predominant, but at locality 3 (Costinha beach) only the P. schmitti was recorded. The regional wet season influenced salinity during the months of the year, producing positive or negative correlations among species found at each locality depending on what was analysed. It is relevant to understand the relationship between fishing resources and environmental variables which provide information about fishing dynamics and permits the development of strategies for the maintenance of stocks and fishing areas, as well as permitting the establishment of public regulations for the better preservation and conservation of marine areas and estuaries on which many species depend for the completion of their life cycles.

Um panorama sobre os estudos de ecologia trófica em ambientes marinhos: Resultados e perspectivas

Classical approaches to trophic ecology of marine species has focused on trophic structure, trophodynamics, dominant and keystone species, ecosystem maturity, energy transfer, and anthropic effects. A recent breakthrough for evaluating the structure of communities has been the application of phylogenetic methods to community ecology. This recent approach is known as community phylogenetics. Although this perspective is still not common in trophic studies, phylogenetic methods promise new insights into the old ecological question on how communities are assembled in time. Integrating phylogenetics and ecosystem function creates the possibility of predicting ecological consequences of biodiversity shifts in a changing world. Once we understand the structure and functioning of the ecosystem in a historical context, we should be able to avoid humanor natural disturbances that draw a system away from its state of maximum complexity.Key words: trophic structure, trophodynamics, keystone species, ecosystem maturity, energy transfer, anthropic effects, community phylogenetics.Abordagens clássicas para estudos de ecologia trófica de species marinhas focam a estrutura trófica, a trofodinâmica, espécies dominantes e espécies-chave, maturidade de ecossistemas, transferência de energia, e efeitos antrópicos. Um avanço recente para avaliar a estrutura de comunidades foi a aplicação de métodos filogenéticos à ecologia de comunidades. Esta abordagem recente é conhecida como filogenia de comunidades. Embora esta perspectiva ainda não seja comum em estudos tróficos, métodos filogenéticos prometem novas abordagens à velha questão ecológica de como entendera organização de comunidades ao longo do tempo. A integração de filogenia com o funcionamneto de ecossistemas cria a possibilidade de prever as consequências de alterações na biodiversidade num mundo em mudança. Uma vez entendida a estruturae o funcionamento do ecossitema num contexto histórico, deveremos poder evitar alterações naturais ou humanas que tendem a desviar o sistema ecológico do seu estado de complexidade máxima.Palavras-chave: estrutura trófica, trofodinâmica, espécies-chave, maturidade de ecossistemas, transferência de energia, efeitos antrópicos, filogenia de comunidades

Precipitation mediates sap flux sensitivity to evaporative demand in the neotropics

Transpiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remains elusive. With a progressively warming climate, atmospheric evaporative demand [i.e., vapor pressure deficit (VPD)] will be increasingly important for plant functioning, becoming the major control of plant water use in the twenty-first century. Using measurements in 34 tree species at seven sites across a precipitation gradient in the neotropics, we determined how the maximum sap flux velocity (vmax) and the VPD threshold at which vmax is reached (VPDmax) vary with precipitation regime [mean annual precipitation (MAP); seasonal drought intensity (PDRY)] and two functional traits related to foliar and wood economics spectra [leaf mass per area (LMA); wood specific gravity (WSG)]. We show that, even though vmax is highly variable within sites, it follows a negative trend in response to increasing MAP and PDRY across sites. LMA and WSG exerted little effect on vmax and VPDmax, suggesting that these widely used functional traits provide limited explanatory power of dynamic plant responses to environmental variation within hyper-diverse forests. This study demonstrates that long-term precipitation plays an important role in the sap flux response of humid tropical forests to VPD. Our findings suggest that under higher evaporative demand, trees growing in wetter environments in humid tropical regions may be subjected to reduced water exchange with the atmosphere relative to trees growing in drier climates