Estructura de tamaños de las comunidades microbianas en sistemas acuáticos salinos del alto Guadalquivir

El presente trabajo aborda el análisis de la estructura de tamaños de la comunidad microbiana de tres ecosistemas acuáticos salinos de la provincia de Jaén (laguna Honda y salinas de San Carlos y de Los Vélez), situados en la cuenca alta del río Guadalquivir. Los tres ecosistemas objeto de estudio presentaron claras diferencias en las condiciones ambientales, con unas concentraciones medias de sales muy oscilantes y que estuvieron comprendidas entre los 14 g/l de la laguna Honda y los 156 g/l registrados en la salina Los Vélez. Una combinación de técnicas de citometría de flujo y microscopía de epifluorescencia ha permitido la rápida caracterización de la estructura de tamaños de la comunidad microbiana de estos sistemas. Los resultados obtenidos describen unas comunidades caracterizadas por unos espectros de biovolumen alejados de la linealidad y con una discontinuidad en la transición entre bacterias y fitoplancton. Es de destacar, además, la gran diferencia existente entre los espectros de la laguna Honda y los de las salinas, con una discontinuidad mucho más patente en estos últimos, de acuerdo a la esperada menor complejidad de la comunidad desarrollada en estos sistemas más extremos.In this paper we analyse the size structure of the planktonic microbial community of three saline aquatic ecosystems of the Jaén Province (Honda Lake, San Carlos and Los Vélez saltern), located in the Alto Guadalquivir basin. The three ecosystems studied presented clear differences in environmental conditions with strongly oscillating mean salinity levels ranging between 14 g/l from Honda Lake and 156 g/l in Los V'elez. Combining flow cytometric and epifluorescence techniques allowed for a rapid characterisation of the size structure of microbial communities of these systems. The results show a non linear size biomass spectrum characterized by one discontinuity in the transition between bacteria and phytoplankton size ranges. Moreover, this discontinuity was broader and more evident in the most saline systems, according to the expected lower complexity of these more extreme ecosystems

Usos del suelo en las cuencas hidrográficas de los humedales del Alto Guadalquivir : importancia de una adecuada gestión

Se ha realizado la delimitación y valoración de los usos del suelo en la cuenca hidrográfica de 22 humedales de la comarca del Alto Guadalquivir. Para dicha valoración se ha diferenciado entre cultivos (herbáceos y arbóreos); vegetación natural (monte bajo), terrenos forestales, pastizales, humedales desecados y terrenos urbanizados. El olivar es la actividad que mayor ocupación de suelo presenta en el territorio estudiado. Las actividades regularmente desarrolladas en el cultivo intensivo del olivar provocan el incremento de perturbaciones que repercuten sobre toda la cuenca de drenaje y particularmente en la calidad de las aguas y la conservación del humedal. Los resultados obtenidos se discuten en el contexto de la conservación de los humedales de la comarca del Alto Guadalquivir.Drainage basin demarcation and the land uses identification have been carried out in 22 wetlands from the Alto Guadalquivir area. The land uses identified were crops (herbaceous and tree crops); natural vegetation; forests; grazing land; desiccated wetland and urban areas. Olive tree growing was the predominant soil use detected. The regular activities carried out in the olive intensive agriculture generate increased perturbations over the whole drainage basin and especially on the water quality and wetland conservation. The results obtained are discussed within the context of the Alto Guadalquivir wetland conservation

Short term fluctuations of zooplankton abundance during autumn circulation in two reservoirs with contrasting trophic state

Zooplankton community in the reservoirs of Maranhao and Santa Luzia (Portugal) were studied during the autumn stratification breakdown and the weeks before it. The results from water transparency, chlorophyll-a and total phosphorus concentrations, calanoid to cyclopoid copepods ratio and zooplankton abundance confirm the different trophic state of both studied reservoirs: mesotrophic-eutrophic (Maranhao) and oligotrophic-mesotrophic (Santa Luzia), as previous studies have reported. Using Copidodiaptomus numidicus to compare both studied reservoirs, we found higher egg production rates in Maranhao than in Santa Luzia. Nevertheless, no relationship was ever found between zooplankton (abundance or egg production rate) and environmental variables (temperature and chlorophyll-a), which may suggest that wide and complex range of factors, abiotic as much as biotic, are involved in zooplankton dynamics during the autumn circulation period.La comunidad zooplanctónica de los embalses de Maranhao y Santa Luzia (Portugal) fue estudiada durante la ruptura de la estratificación otoñal y las semanas previas. Los resultados de transparencia del agua, concentración de clorofila-a y concentración de fósforo total, así como la razón entre copépodos calanoides y ciclopoides y la abundancia de zooplancton confirman el diferente estado trófico entre ambos embalses: mesotrófico-eutrófico (Maranhao) y oligotrófico-mesotrófico (Santa Luzia), como estudios previos habían mostrado. Utilizando al copépodo Copidodiaptomus numidicus para comparar ambos embalses, se ha observado una mayor tasa de producción de huevos en Maranhao que en Santa Luzia. Sin embargo, en ningún caso se ha encontrado una relación entre el zooplancton (abundancia o tasa de producción de huevos) y las variables ambientales (temperatura y concentración de clorofila-a), por lo que se sugiere que una amplia y compleja gama de factores, tanto bióticos como abióticos, deben de estar involucrados en la dinámica del zooplancton durante el periodo de circulación otoñal

Identifying environmental drivers of benthic diatom diversity: the case of Mediterranean mountain ponds

[EN] This study aims at elucidating the environmental factors controlling benthic diatom diversity and uniqueness in Mediterranean mountain ponds. Samples of periphytic diatoms were collected in 45 ponds in Andalusia, south of Spain, and analysed by standard methods. Data analysis reveals that diatom diversity is mainly controlled by elevation and hydroperiod. Contrary to the usual findings in the literature, the highest scores on Shannon’s diversity index were found in high-elevation temporary ponds, but this effect is hidden by lake clustering in the analysed dataset. Significant distance-decay similarity (DDS) trends were detected in the analysis of floristic composition among the samples, stressing the importance of spatial factors that may override the effect of other abiotic factors. These findings highlight the role of isolation and dispersal limitation in the configuration of the biogeographical patterns of benthic diatomsSIThis work is part of the project ``Andalusian mountain wetlands: inventory, typologies and conservation'' which is funded by the Center for Advanced Studies in Earth Sciences (CEACTierra) at the University of Jaén. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip

Evaluation of factors influencing farm profit in extensive ruminant systems using structural equations

Extensive livestock farming in general is more sustainable than intensive methods. However, its profitability is usually low, which can affect the motivation of young people to take up livestock rearing, and often leads them to seek employment elsewhere. The aim of this paper is to study the factors affecting the Farm profit of extensive ruminant farms in marginal areas of Southern Chile. To achieve this, we used Structural Equation Modeling (SEM), which provides an in- depth view of the relationships of different variables (items) with Farm profit (target variable). The exogenous construct that we obtained (Structural variable), consisting of the items Grazing area, Hired labor and Total Livestock Units (LU), exerts a direct, significant explanatory influence on the endogenous construct (Economic variable), which includes the items Hay cost, Total sales and Economic records, showing a significant, positive slope in the target variable (Farm profit). These structural variables largely condition the entire economic process. However, business decisions linked to farm management influence structural factors and affect the value of income, expenditure and Farm profit. Studying the factors which influence Farm profit sheds light on the main weaknesses of the system in terms of the financial operation, as well as on potential improvements, encompassing the social, technical and environmental dimensions

The high abundance of wild ungulates in a mediterranean region: is this compatible with the European rabbit?

This is an Open Access article.The landscape in southern Iberia has, over the last four decades, altered as a result of the land abandonment, while the abundance of wild boar Sus scrofa and red deer Cervus elaphus has simultaneously increased, and some key prey species such as the European rabbit Oryctolagus cuniculus have declined. In this work we explore: 1) the relationships between big game species (red deer and wild boar) and rabbit abundance, and 2) whether these relationships could have effects on food quality (total nitrogen available in the pasture and percentage of leguminosae) and food availability of (herbaceous cover). We therefore selected nine big game estates with a range of abundance as regards ungulates and similar Mediterranean habitat. Wild boar abundance was statistically negative in relation to rabbit abundance, while no significant statistical relationships between rabbit abundance and habitat structure and forage quality were evidenced. However, wild boar abundance, but not that of red deer, was negatively associated with leguminosae cover, and the percentage of surface rooted by wild boar was negatively associated with the percentage of herbaceous cover. Overall, our results suggest that the abundance of wild boar is negatively related to that of rabbits, and could have a negative effects on rabbit abundances by food competition as a result of: 1) a decrease in herbaceous coverage and leguminosae in the pasture and 2) an increase in the total percentage of soil disturbed as a result of rooting.We should like to thank to the Andalucía Autonomous Government’s Environmental Council for financing this work via a project to improve the habitat of the black vulture in Córdoba province.Peer Reviewe

Proposal of environmental indicators of sustainability for ruminant pastoral production system

Este artículo es la continuación de un estudio previo presentado por los autores en el Seminario FAO-CIEHAM (Organización para la Agricultura y la Alimentación- Centro Internacional de Altos Estudios Agronómicos Mediterráneos) celebrado en Sevilla, España, en 2005, en el cual se realizó un análisis preliminar acerca del uso de los indicadores de la FAO-CIEHAM para evaluar la sustentabilidad de granjas con pequeños rumiantes. El artículo que se presenta ofrece una lista de 48 indicadores ambientales genéricos, adaptada a las granjas con pequeños rumiantes con relación a ocho aspectos: prácticas agrícolas, suelo, agua, paisaje, energía, residuos, bienestar animal y biodiversidad. Se necesita trabajo adicional para completar y perfeccionar esta lista, la cual se ha obtenido a partir de la consulta a expertos y de una revisión de metodologías existentes.This paper is the continuation of a previous study presented by the authors in the FAO-CIEHAM (Food and Agriculture OrganizationInternational Center for Advanced Mediterranean Agronomic Studies) seminar in Seville in 2005, in which, a preliminary analysis was made of the use of FAO-CIHEAM indicators to evaluate sustainability of small ruminant farms. The paper presented provides a list of 48 generic environmental indicators adapted to small ruminant farms with respect to eight aspects: agricultural practices, soil, water, landscape, energy, residues, animal welfare, and biodiversity. Further work is necessary to complete and perfect this list which has been obtained from a review of methodologi