Un modelo conceptual sobre el funcionamiento de los ríos mediterráneos sometidos a perturbaciones naturales (riadas y sequías)

The Mediterranean regions are prone to suffer extraordinary flash-floods and prolonged droughts. Between these extreme events, there are small floods and droughts that are more common and more predictable. These smaller floods and droughts, along with the others mentioned before generate an extraordinarily complex temporal hydrological picture whose affects have been partly described by different authors, including those affecting the human population. The information compiled during nearly two decades by the group of Ecology of Continental Waters of the University of Murcia, about the effects of these events on rivers of the Segura River Basin, allows for elaborating a conceptual model about the function of several physical, physico-chemical, and biological parameters in rivers in the southwest, in particular and Mediterranean rivers in general.Las regiones mediterráneas son proclives a sufrir avenidas extraordinarias y sequías prolongadas. Entre estos eventos extremos, se sitúan las crecidas y estiajes más habituales y predecibles que, junto a los anteriores configuran un cuadro hidrológico temporal extraordinariamente complejo cuyos efectos han sido descritos parcialmente por diferentes autores, incluidos aquellos que afectan a la población humana. La información recogida durante casi dos décadas por el Grupo de Ecología de Aguas Continentales de la Universidad de Murcia, sobre los efectos de estos eventos en ríos de la Cuenca del Segura, permite elaborar un modelo conceptual sobre el funcionamiento de distintos parámetros físicos, físico-químicos y biológicos en ríos del sureste, en particular y mediterráneos, en general

Spatial scale effects on taxonomic and biological trait diversity of aquatic macroinvertebrates in Mediterranean streams

We examined the effect of spatial scale on aquatic macroinvertebrate communities in Mediterranean streams from six basins distributed across southern Europe, including Spain, France, Italy, and Greece. We classified the studied streams according to their long-term aquatic regime into the three following types: (i) permanent (P), (ii) intermittent with summer pools (I-P), and (iii) intermittent with summer dry channels (I-D). For each stream type, we analyzed taxonomic and trait diversity, as well as the composition of the macroinvertebrate community, following a spatially nested design at three spatial scales of analysis: microhabitat (substratum patches), mesohabitat (pools vs. riffles), and macrohabitat (streams). In order to assess intrinsic seasonal variability in streams from the Mediterranean region, 20 Surber samples were taken from each stream according to meso- and microhabitat frequency in the wet and the dry season during 2010. Given the need for adaptation to specific hydrological conditions and the fact that microhabitats should encompass the niche requirements of particular taxa, we hypothesized that this spatial scale would have a greater influence on macroinvertebrate taxa composition and biological traits than the other two larger spatial scales in intermittent streams. We observed that patterns in the relative importance of variance components across hierarchical spatial scales changed with time because low flow or droughts altered both mesohabitat preva - lence and microhabitat composition. Our results confirm the importance of the microhabitat scale in I-P streams in the wet season but not in the dry one, when a loss of microhabitat diversity occurred. Stream-to-stream variability was more important in P and I-D streams. Our study also explored the relationships between traits and aquatic regimes. We found that aquatic macroinvertebrates inhabiting permanent streams exhibited traits related to the longer duration of life cycles in these rivers (e.g. large size of adult stages) and adaptations to flowing conditions (e.g. modes of aquatic dispersal), whereas aquatic macroinvertebrates inhabiting intermittent streams with summer pools had traits adapted to depositional conditions and ecological preferences for confined habitats (i.e. disconnected pools without flow). Finally, aquatic macroinvertebrates from intermittent streams with summer dry channels had adaptations conferring ability to survive periods with no water (e.g. modes of aerial dispersal, resistant stages). These results indicate that microhabitat conditions should not be neglected as they can play an important role in certain situations

A biological tool to assess flow connectivity in reference temporary streams from the Mediterranean Basin

Many streams in the Mediterranean Basin have temporary flow regimes. While timing for seasonal drought is predictable, they undergo strong inter-annual variability in flow intensity. This high hydrological variability and associated ecological responses challenge the ecological status assessment of temporary streams, particularly when setting reference conditions. This study examined the effects of flow connectivity in aquatic macroinvertebrates from seven reference temporary streams across the Mediterranean Basin where hydrological variability and flow conditions are well studied. We tested for the effect of flow cessation on two streamflow indices and on community composition, and, by performing random forest and classification tree analyses we identified important biological predictors for classifying the aquatic state either as flowing or disconnected pools. Flow cessation was critical for one of the streamflow indices studied and for community composition. Macroinvertebrate families found to be important for classifying the aquatic state were Hydrophilidae, Simuliidae, Hydropsychidae, Planorbiidae, Heptageniidae and Gerridae. For biological traits, trait categories associated to feeding habits, food, locomotion and substrate relation were the most important and provided more accurate predictions compared to taxonomy. A combination of selected metrics and associated thresholds based on the most important biological predictors (i.e. Bio-AS Tool) were proposed in order to assess the aquatic state in reference temporary streams, especially in the absence of hydrological data. Although further development is needed, the tool can be of particular interest for monitoring, restoration, and conservation purposes, representing an important step towards an adequate management of temporary rivers not only in the Mediterranean Basin but also in other regions vulnerable to the effects of climate change

Ensayo de una tipología de las cuencas mediterráneas del proyecto GUADALMED siguiendo las directrices de la Directiva Marco del Agua

RESUMEN Utilizando la propuesta de tipología de ríos de la Directiva Marco del Agua en su anexo 2 se realiza un ensayo tipológico de los puntos de muestreo del proyecto GUADALMED. Según el sistema A, se presentan 16 ecotipos, lo que se juzga poco adecuado para la gestión de los mismos y sin una base ecológica que lo justifique. De acuerdo con la selección previa hecha por los miembros del grupo GUADALMED para 5 de estos ecotipos no habría estaciones de referencia. Con algunas variables medidas en los puntos de muestreo y otras de tipo geológico e hidromorfológico, se realiza un ensayo tipológico usando el sistema B. El método implica un análisis de la correlación entre variables, un cluster de las estaciones utilizando el método K-means y un análisis discriminante de cuáles son las variables que distinguen estos grupos. El estudio da como resultado la caracterización de 6 ecotipos que sin embargo, a juicio de los miembros del proyecto GUADALMED, no recogen la variedad de tipos de ríos mediterráneos. Valorando cualitativamente parámetros no introducidos (por falta de datos) en el análisis K-means, se propone una tipología provisional en 9 grupos. Un análisis de las comunidades de macroinvertebrados (a nivel taxonómico de familia) revela un grado importante de coherencia entre las familias asociadas a cada tipo y sus preferencias ecológicas conocidas. ABSTRACT A preliminary analysis was conducted of the river types in the GUADALMED project using the river typology proposed in the Water Framework Directive (WFD) in its annex 2. Using System A, 16 different types were found, a number too high for water management purposes and such typology lacks a supportive ecological basis. For 5 of these 16 ecotypes, no reference stations exist. Reference stations were selected a priori in project GUADALMED for each of the 12 basins sampled. An ecotypological analysis was performed using System B of the WFD using several variables measured during the study, and other variables obtained from maps or data bases (e.g., geology). The method included the analysis of the calibration between variables, the clustering of stations by the K-means method and a discriminant analysis. The latter revealed which factors were distinctive of each group. Six ecotypes were established for the GUADALMED study sites. These, however, do not include all the mediterranean-type streams of the region. This is mainly due to the absence in the data base of some important features of streams in the data base such as temporality or the dependence of flow on the presence of karstic aquifers, attribute

Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI 2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining https://researchonline.ljmu.ac.uk/images/research_banner_face_lab_290.jpgunderweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesity

Caracterización del estado ecológico de ríos mediterráneos ibéricos mediante el índice IBMWP (antes BMWP')

En base a los datos obtenidos a lo largo de la primera fase del proyecto GUADALMED (1999-2001), se estudia la calidad biológica de las aguas de 65 ríos de 12 cuencas mediterráneas ibéricas y el comportamiento del índice IBMWP ("Iberian Biomonitoring Working Party"; antes BMWP"). Se proponen unas bases para el establecimiento de las clases de calidad para la evaluación de estado ecológico de los ríos, siguiendo las directrices de la Directiva Marco del Agua, basadas en los valores del índice obtenidos en las estaciones de referencia de cada una de las tipologías de ríos obtenidas en el estudio. Tras la comparación entre las cinco clases originales del índice y las posibles nuevas acotaciones obtenidas se observó una total coincidencia para todos los casos en que se contaba con un número de estaciones de referencia elevado (>50), observándose discrepancias respecto a aquellas tipologías de ríos en que el número de estaciones era escaso (50), while discrepancies were observed within river types when the number of stations was low (<50). Therefore, we propose that the same IBMWP classes continue to be used, until a greater number of reference stations are available, which would be necessary to evaluate whether discrepancies observed are due to specific differences of river types, or are due to an insufficient representation of reference stations of some river types

Criterios para la selección de condiciones de referencia en los ríos mediterráneos. Resultados del proyecto GUADALMED

La Directiva Marco del Agua (DMA) establece la necesidad de definir las condiciones de referencia, que sirvan de patrón del estado ecológico del resto de estaciones del mismo ecotipo. Varios son los criterios que pueden ser utilizados para la selección de las condiciones de referencia. En el proyecto GUADALMED cinco localidades por cuenca muestreada, fueron escogidas a priori según la experiencia de los expertos en cada zona, uno de los criterios contemplados en la DMA. Los resultados mostraron en muchas de las estaciones seleccionadas (un 72%) una calidad biológica alterada (IBMWP <100 en todas las campañas muestreadas) y un bosque de ribera perturbado (QBR <75). A partir de estos resultados se analizó si era posible el establecimiento de una serie de criterios que ayudaran a establecer condiciones de referencia. Para ello se seleccionaron diferentes criterios como la conservación del bosque de ribera, los usos naturales de la cuenca, la naturalidad del canal fluvial, la ausencia de embalses que regularan el caudal, un hábitat del lecho adecuado y concentraciones bajas de parámetros físico-químicos, en cada uno de los puntos estudiados. Algunas estaciones cumplían todos los criterios, mientras que otras podrían fácilmente cumplirlos reubicando el punto de muestreo aguas arriba o abajo del río o mediante técnicas de restauración. Los resultados fueron comparados con la tipología mediante el Sistema B establecida en otro trabajo de este volumen. En algunos ecotipos, la falta de estaciones de referencia y la imposibilidad de encontrarlas dadas las características de la cuenca y el tramo, implica la imposibilidad de establecer condiciones de referencia y la necesidad de establecer el Máximo Potencial Ecológico. Al comparar los criterios establecidos para cada estación con los valores de los índices biológicos hallados en todas las campañas, se observa que los criterios establecidos son adecuados, ya que las estaciones que los cumplen tienen un IBMWP y QBR superior. Este trabajo pretende establecer unos criterios generales que serán utilizados como base para la selección y validación de condiciones de referencia en la segunda fase del proyecto GUADALMED. ABSTRACT The water Frame Directive (WFD) establishes the need to define reference conditions in order to determine the ecological status of all the test sites from each ecotype. Several criteria may be used to select reference conditions. In the GUADALMED project, five localities per basin were selected a priori according to the experience of experts, which is one of the criteria considered in the WFD. Results showed that in 72% of selected reference conditions, water quality was poor (IBMWP<100 in all sampled seasons) and the riparian vegetation, altered (QBR<75). Consequently, we established a set of new criteria for appropriate selection of reference conditions for natural riparian vegetation status, natural basin uses, unaltered fluvial channel, absence of reservoirs, diverse river habitat conditions and low nutrient concentrations. A few sites conform to all these criteria, whereas others may comply when a site upstream or downstream is considered instead, or after restoration techniques are applied. Results obtained were compared with the previously established System B typologies. For some ecotypes, no reference sites were found occasionally because of the difficulty in finding given basin or river reach characteristics. In these cases, a"Maximum Ecological Potential" was used instead of the reference condition. When the criteria established were compared with the biological indices across seasons for each site, a positive and significant relationship was found between all criteria and the IBMWP and QBR indices. Here, we present a set of criteria for use as a general framework to select and validate reference condition during the second phase of the project GUADALMED

Las riberas de los rios mediterraneos y su calidad: el uso del indice QBR

Se ha aplicado el QBR (índice de calidad del bosque de ribera) a 157 estaciones de muestreo localizadas en ríos pertenecientes a 12 cuencas diferentes del ámbito mediterráneo español. Los resultados indican que más del 34 % de las estaciones muestran valores de calidad buenos y muy buenos (QBR > 75), mientras que el 45 % presenta valores de mala y pésima calidad (QBR < 50). Según una tipología previa establecida para clasificar las estaciones de muestreo, los valores de mayor calidad de QBR se dan en estaciones de cabecera de cuencas calcáreas y en las zonas de karst. Los tipos denominados temporales y ramblas presentan los valores más bajos de calidad, o no tiene representantes de máxima calidad. La ausencia o escasez de bosques de riberas de máxima calidad en las cuencas del sur peninsular puede explicarse por el gradiente de aridez que se establece desde el norte hacia el sur. Además existe un evidente deterioro de las riberas desde las cabeceras a las desembocaduras de los ríos, de manera que ambos factores influyen en el estado actual de las riberas de los ríos mediterráneos ibéricos. Finalmente se discute la utilidad y limitaciones del QBR en ríos sometidos a situaciones de estrés hídrico o ambiental

Las riberas de los rios mediterraneos y su calidad: el uso del indice QBR

Se ha aplicado el QBR (índice de calidad del bosque de ribera) a 157 estaciones de muestreo localizadas en ríos pertenecientes a 12 cuencas diferentes del ámbito mediterráneo español. Los resultados indican que más del 34 % de las estaciones muestran valores de calidad buenos y muy buenos (QBR > 75), mientras que el 45 % presenta valores de mala y pésima calidad (QBR < 50). Según una tipología previa establecida para clasificar las estaciones de muestreo, los valores de mayor calidad de QBR se dan en estaciones de cabecera de cuencas calcáreas y en las zonas de karst. Los tipos denominados temporales y ramblas presentan los valores más bajos de calidad, o no tiene representantes de máxima calidad. La ausencia o escasez de bosques de riberas de máxima calidad en las cuencas del sur peninsular puede explicarse por el gradiente de aridez que se establece desde el norte hacia el sur. Además existe un evidente deterioro de las riberas desde las cabeceras a las desembocaduras de los ríos, de manera que ambos factores influyen en el estado actual de las riberas de los ríos mediterráneos ibéricos. Finalmente se discute la utilidad y limitaciones del QBR en ríos sometidos a situaciones de estrés hídrico o ambiental