A Geographical Information System for some Mediterranean benthic communities

International audienceThis paper describes a regional geographical information system (GIS) for some Mediterranean benthic communities. The area covered by the GIS lies between the cities of La Ciotat and Giens in southeast France. The distinctive characteristics of this GIS compared with others usually described in the literature, are that all its layers describe the same theme but as seen at different moments with different scales and techniques used by different oceanographers. A method was devised to synthesize, on a pixel basis, the content of all these layers

Flora algal de la cuenca del río Guadalquivir: Su valor en la determinación de la ecorregionalización de la cuenca

In compliance with the Water Framework Directive of the European Union, we needed to diagnose the ecologic quality of the different sections of the rivers of the Guadalquivir basin. In order to establish a regional classification of the water bodies by a grouping into areas of similar characteristics, we took into consideration the benthic phycologic flora of the Guadalquivir-River basin. Benthic algae, being one of the groups of organisms that best define the water quality of rivers, are useful for characterizing the basin´s ecoregionalization. We collected multihabitat samples in 109 georeferenced reaches and identified 777 algal taxa: 397 Bacillariophyceae (diatoms), 181 Chlorophyta, 148 Cyanoprokariota, 41 Euglenophyta, 4 Chrysophyceae, 3 Dinophyta, 2 Rodophyta, and 1 Cryptophyta. Except for Achnanthidium minutissimum?it being present in nearly all the sites?the species composition enabled the identification of 4 groups: (1) the Sierra-Morena rivers with a predominantly siliceous substrate and concomitantly low mineralized water (< 250 mg/L); (2) the Doñana and lower-Guadiamar rivers of the lower-Guadalquivir with a high relative proportion of sodium; (3) rivers with any kind of disturbance, principally organic contamination, grouped regardless of their geographical location; (4) rivers of high calcium content that, though constituting a heterogeneous group, the majority of which belong to the Betic-Mountain region. According to our results, the subbasin was the one that determined the composition of the periphyton. The categorization of the rivers according to biota obtained in the present work differs from the hydrogeomorphological classification established by the Guadalquivir Hydrographic Confederation.En cumplimiento con la Directiva Marco para las Políticas del Agua (DMA) de la Unión Europea fue necesario diagnosticar la calidad ecológica de los distintos tramos de los ríos de la cuenca del Guadalquivir. Para establecer una regionalización de las masas de agua agrupándolas en zonas de similares características se tomó en consideración la flora ficológica bentónica de la cuenca del río Guadalquivir y su valor en la ecorregionalización de la cuenca debido a que las algas bentónicas están entre los grupos de organismos que mejor definen la calidad del agua de los ríos. Se extrajeron muestras multihábitat en 109 tramos georeferenciados. Se identificaron 777 taxa algales: 397 Bacillariophyceae (diatomeas), 181 Chlorophyta, 148 Cyanoprokariota, 41 Euglenophyta, 4 Chrysophyceae, 3 Dinophyta, 2 Rodophyta y 1 Cryptophyta. Con excepción de Achnanthidium minutissimun, que estuvo presente en casi todos los sitios, según la composición algal pueden identificarse 4 grandes grupos: 1) Sierra Morena, con sustrato predominantemente silíceo y concomitantemente aguas poco mineralizadas (< 250 mg/L); 2) ríos de la depresión del Bajo Guadalquivir, Doñana y bajo Guadiamar con una proporción relativamente elevada de sodio; 3) ríos con algún tipo de perturbación, principalmente contaminación orgánica, agrupados independientemente de su situación geográfica, 4) ríos con alto contenido de calcio en sus aguas que, si bien forman un grupo heterogéneo, la mayoría pertenecen a la región de las Montañas Béticas. De acuerdo con nuestros resultados, la subcuenca fue la que determinó la composición del perifiton. La categorización de los ríos según la biota obtenida en el presente trabajo difiere de la clasificación hidrogeomorfológica establecida por la Confederación Hidrográfica del Guadalquivir.Fil: Casco, Maria Adela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Ficología; ArgentinaFil: Reyes, Isabel. Universidad de Sevilla; EspañaFil: Martín, Gonzalo. Universidad de Sevilla; EspañaFil: Fernández, María R.. Universidad de Sevilla; EspañaFil: Sala, Silvia Estela. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Ficología; ArgentinaFil: Toja, Julia. Universidad de Sevilla; Españ

Efficient sampling methodologies for lake littoral invertebrates in compliance with the European Water Framework Directive

Lake shores are characterised by a high natural variability, which is increasingly threatened by a multitude of anthropogenic disturbances including morphological alterations to the littoral zone. The European Water Framework Directive (EU WFD) calls for the assessment of lake ecological status by monitoring biological quality elements including benthic macroinvertebrates. To identify cost- and time-efficient sampling strategies for routine lake monitoring, we sampled littoral invertebrates in 32 lakes located in different geographical regions in Europe. We compared the efficiency of two sampling methodologies, defined as habitat-specific and pooled composite sampling protocols. Benthic samples were collected from unmodified and morphologically altered shorelines. Variability within macroinvertebrate communities did not differ significantly between sampling protocols across alteration types, lake types and geographical regions. Community composition showed no significant differences between field composite samples and artificially generated composite samples, and correlation coefficients between macroinvertebrate metrics calculated with both methods and a predefined morphological stressor index were similar. We conclude that proportional composite sampling represents a time- and cost-efficient method for routine lake monitoring as requested under the EU WFD, and may be applied across various European geographical regions

Hyporheic invertebrates as bioindicators of ecological health in temporary rivers: a meta-analysis

Worldwide, many rivers cease flow and dry either naturally or owing to human activities such as water extraction. However, even when surface water is absent, diverse assemblages of aquatic invertebrates inhabit the saturated sediments below the river bed (hyporheic zone). In the absence of surface water or flow, biota of this zone may be sampled as an alternative to surface water-based ecological assessments. The potential of hyporheic invertebrates as ecological indicators of river health, however, is largely unexplored. We analysed hyporheic taxa lists from the international literature on temporary rivers to assess compositional similarity among broad-scale regions and sampling conditions, including the presence or absence of surface waters and flow, and the regional effect of hydrological phase (dry channel, non-flowing waters, surface flow) on richness. We hypothesised that if consistent patterns were found, then effects of human disturbances in temporary rivers may be assessable using hyporheic bioindicators. Assemblages differed geographically and by climate, but hydrological phase did not have a strong effect at the global scale. However, hyporheic assemblage composition within regions varied along a gradient of higher richness during wetter phases

Modeling macroalgal forest distribution at Mediterranean scale : present status, drivers of changes and insights for conservation and management

Macroalgal forests are one of the most productive and valuable marine ecosystems, but yet strongly exposed to fragmentation and loss. Detailed large-scale information on their distribution is largely lacking, hindering conservation initiatives. In this study, a systematic effort to combine spatial data on Cystoseira C. Agardh canopies (Fucales, Phaeophyta) was carried out to develop a Habitat Suitability Model (HSM) at Mediterranean scale, providing critical tools to improve site prioritization for their management, restoration and protection. A georeferenced database on the occurrence of 20 Cystoseira species was produced collecting all the available information from published and grey literature, web data portals and co-authors personal data. Data were associated to 55 predictor variable layers in the (ASCII) raster format and were used in order to develop the HSM by means of a Random Forest, a very effective Machine Learning technique. Knowledge about the distribution of Cystoseira canopies was available for about the 14% of the Mediterranean coastline. Absence data were available only for the 2% of the basin. Despite these gaps, our HSM showed high accuracy levels in reproducing Cystoseira distribution so that the first continuous maps of the habitat across the entire basin was produced. Misclassification errors mainly occurred in the eastern and southern part of the basin, where large gaps of knowledge emerged. The most relevant drivers were the geomorphological ones, followed by anthropogenic variables proxies of pollution and urbanization. Our model shows the importance of data sharing to combine a large number of spatial and environmental data, allowing to individuate areas with high probability of Cystoseira occurrence as suitable for its presence. This approach encourages the use of this modeling tool for the prediction of Cystoseira distribution and for supporting and planning conservation and management initiatives. The step forward is to refine the spatial information of presence-absence data about Cystoseira canopies and of environmental predictors in order to address species-specific assessments.peer-reviewe