Integrating chemical and biological status assessment: assembling lines of evidence for the evaluation of river ecosystem risk

This paper describes various approaches to evaluating ecological risk in rivers affected by multiple chemical stressors, with emphasis on biofilm and invertebrate community responses. Metrics should be considered as different lines of evidence that, when weighted, form an advanced weight of evidence approach to establishing the environmental risk on a basin scale. Combination of field surveys to obtain observational data of communities, in situ experiments, toxicological sediment tests and a good chemical description of the medium (water and sediment) helps give an integrative view of the chemical and biological state of a river ecosystem. The greater and more distinct the variables used, the greater is our ability to identify the effects of major stressors impairing communities. Weight of evidence is an integrative methodology for tackling the challenge of determining causal relations and applying this knowledge in the decision-making processes of river management

Food web of a tropical high mountain stream: effects of nutrient addition

In order to define the effect of nutrient enrichment on trophic webs in an Andean mountain stream we performed an experiment using stable isotope ratios (δ15N and δ13C) to analyze different trophic compartments: 1) basal level: CPOM and biofilm; 2) primary consumers - macroinvertebrates: collector-gatherers (Heterelmis sp., Thraulodes sp. and Trichorythodes sp.), and collectorfilterers (Simulium sp.); 3) predators - fish (Oncorhynchus mykiss and Trichomycterus bogotensis). The average fractionation of nitrogen among the primary consumers with respect to CPOM was 4.7 , and 1.7 with respect to biofilm. Predators incremented their δ15N signal by 5.9 % with respect to primary consumers. A depletion of δ15N was observed in Impact with respect to Control reach after fertilization in different compartments (biofilm, Heterelmis, Simulium andTricorythodes), while depletion was not significant for top predators. In most cases, the δ13C signal of biofilm overlapped with that of primary consumers, but a clear enrichment was observed with respect to CPOM. Macroinvertebrate gut contents showed fine detritus to be their most abundant food, and that in general there were no changes in diet as a consequence of nutrient enrichment. The only exception was Heterelmis, who increased its consumption in the Impact reach

Catalyst-Free Vapor-Phase Method for Direct Integration of Gas Sensing Nanostructures with Polymeric Transducing Platforms

Tungsten oxide nanoneedles (NNs) are grown and integrated directly with polymeric transducing platforms for gas sensors via aerosol-assisted chemical vapor deposition (AACVD) method. Material analysis shows the feasibility to grow highly crystalline nanomaterials in the form of NNs with aspect ratios between 80 and 200 and with high concentration of oxygen vacancies at the surface, whereas gas testing demonstrates moderate sensing responses to hydrogen at concentrations between 10 ppm and 50 ppm, which are comparable with results for tungsten oxide NNs grown on silicon transducing platforms. This method is demonstrated to be an attractive route to fabricate next generation of gas sensors devices, provided with flexibility and functionality, with great potential in a cost effective production for large-scale applications

Bottom-up effects of streambed drying on consumer performance through changes in resource quality

Stream flow intermittency and subsequent streambed drying, which already occurs in most biomes worldwide, is expected to increase in many regions due to both climate change and increased water demand. We studied the effects of streambed drying on leaves and epilithic biofilm and their effects on potential consumers. In the field, resources were conditioned according to the following treatments: (i) continuously submerged (PERM), (ii) submerged, exposed to the dry streambed and then submerged again (INT), or (iii) conditioned in the dry streambed and only allowed instream conditioning for 1 week (DRY, only for leaves). The results showed that drying affects resource quality, and the effects on biofilm were more severe than those on leaves. Both DRY leaves and INT biofilm showed lower microbial colonization and nitrogen accrual, whereas INT leaves had similar characteristics to PERM leaves. Drying resulted in decreased shredder and herbivore consumption rates and detritivore growth. Our results suggest that bottom-up effects of drying through changes in resource quality can constrain detritivore growth in temporary streams, potentially affecting stream secondary production and invertebrate-mediated organic matter cycling under a drier climate scenario

Aprender Psicología a través de los textos.

This study focused on the tasks set by Psychology lecturers teaching the undergraduate course that involve reading and producing written texts. Via ananalysis of the published curricula for the 28 core and obligatory courses that comprise the degree, we determined the frequency and type of a) reading activities and b) hybrid activities involving reading and writing, and their distribution over the six first semesters. The results indicate a high number of reading tasks and a much lower percentage of hybrid tasks. In turn, the more frequently used hybrid tasks -completing questionnaires, reports on practical sessions- presented far less complexity than tasks used less frequently, such as writing summaries or essays based on more than one source

Contrary effects of flow intermittence and land uses on organic matter decomposition in a Mediterranean river basin

Flow interruption in intermittent rivers (IRs) generates a mosaic of terrestrial and aquatic habitats across the river network affecting ecosystem processes, as organic matter (OM) decomposition. Water use for farming in arid and semi-arid climates intensifies the dry conditions and affects local river characteristics. In that way, flow intermittence and the distribution of land uses may affect the OM processing along the river. To understand the role of IRs in global OM dynamics and how global change affecting water flow regimes determines these dynamics, it is important to estimate OM-processing rates at a basin scale. The aim of this study was to evaluate the effect of the intensity of flow intermittence on OM processing, and how this effect was modulated by local environmental factors related to land uses across a Mediterranean river basin. To do this, wood decomposition (mass loss and fungal biomass) was selected as a functional indicator. Drying duration and frequency were measured to characterize flow intermittence in different reaches along the river, as well as local environmental factors. Linear models stablished the role of factors on decomposition. The results showed that differences in decomposition rates across the river network were negatively related to the duration of flow interruption. Dissolved inorganic nitrogen associated with agriculture counteracted the negative effect of intermittence on mass loss (increasing by up to three times); but with a higher duration of dry conditions, its effect was insignificant. An increase of 20% of canopy (higher in natural areas) resulted in increases of up to 5% of mass loss. Overall, our study is relevant to understanding the interaction between flow intermittence and land uses on OM processing, especially considering the intensification of flow intermittence and its increased distribution to other regions, which is expected to be a consequence of climate warming and human activities

Placa homogeneizadora de temperatura para microdispositivos térmicamente aislados

Referencia OEPM: P9601571.-- Fecha de solicitud: 12/07/1996.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).Placa homogeneizadora de temperatura para microdispositivos térmicamente aislados (ver figura en archivo de texto adjunto). El objeto de la presente invención es el desarrollo de una microestructura térmicamente aislada con zonas de temperatura muy homogénea y controlada. Dichas estructuras son la base de distintos tipos de sensores microelectrónicos ya existentes, en los que un cierto material o elemento sensible se deposita sobre una estructura térmica que debe trabajar a una temperatura conocida. Es aplicable a sistemas de medida microelectrónica basados en microsensores de silicio.Peer reviewe

Multiple stressors in Mediterranean freshwater ecosystems: The Llobregat River as a paradigm

Hydrological modifications drive other ecological stressors of freshwater ecosystems and interact with them. The present paper examines the relevance of hydrological disturbances resulting from global change by presenting the case of the Llobregat River, a highly disturbed system in NE Spain. The Llobregat is a clear example of a Mediterranean river suffering from multiple stressors. Both the distribution and abundance of organisms and ecosystem functioning as a whole are greatly determined by water scarcity, water salinity, nutrient concentration, and organic (and inorganic) pollution. Structural drought exacerbates these problems, as the capacity to dilute pollutants is ompromised. Controlling water abstraction and limiting nutrient and pollutant inputs downstream are essential to the structural and functional recovery of biological communities and to maximizing the ecosystem services provided by the Llobregat River

Effects of riparian vegetation removal on nutrient retention in a Mediterranean stream

We examined the effects of riparian vegetation removal on algal dynamics and stream nutrient retention efficiency by comparing NH4-N and PO4-P uptake lengths from a logged and an unlogged reach in Riera Major, a forested Mediterranean stream in northeastern Spain. From June to September 1995, we executed 6 short-term additions of N (as NH4Cl) and P (as Na2HPO4) in a 200-m section to measure nutrient uptake lengths. The study site included 2 clearly differentiated reaches in terms of canopy cover by riparian trees: the first 100 m were completely logged (i.e., the logged reach) and the remaining 100 m were left intact (i.e., the shaded reach). Trees were removed from the banks of the logged reach in the winter previous to our sampling. In the shaded reach, riparian vegetation was dominated by alders (Alnus glutinosa). The study was conducted during summer and fall months when differences in light availability between the 2 reaches were greatest because of forest canopy conditions. Algal biomass and % of stream surface covered by algae were higher in the logged than in the shaded reach, indicating that logging had a stimulatory effect on algae in the stream. Overall, nutrient retention efficiency was higher (i.e., shorter uptake lengths) in the logged than in the shaded reach, especially for PO4-P. Despite a greater increase in PO4-P retention efficiency relative to that of NH4-N following logging, retention efficiency for NH4-N was higher than for PO4-P in both study reaches. The PO4-P mass-transfer coefficient was correlated with primary production in both study reaches, indicating that algal activity plays an important role in controlling PO4-P dynamics in this stream. In contrast, the NH4-N mass-transfer coefficient showed a positive relation-ship only with % of algal coverage in the logged reach, and was not correlated with any algal-related parameter in the shaded reach. The lack of correlation with algal production suggests that mechanisms other than algal activity (i.e., microbial heterotrophic processes or abiotic mechanisms) may also influence NH4-N retention in this stream. Overall, this study shows that logging disturbances in small shaded streams may alter in-stream ecological features that lead to changes in stream nutrient retention efficiency. Moreover, it emphasizes that alteration of the tight linkage between the stream channel and the adjacent riparian zone may directly and indirectly impact biogeochemical processes with implications for stream ecosystem functioning

Drying niches of aquatic macroinvertebrates identify potential biomonitoring indicators in intermittent and ephemeral streams

Intermittent rivers and ephemeral streams (IRES) compose the majority of draining networks on Earth, supporting a unique fraction of biodiversity. Despite their high ecological value, IRES are increasingly threatened by global change and require appropriate biomonitoring and restoration tools. However, indices and indicators used in routine biomonitoring programs are often confounded by drying effects. This occurs because most pollutionsensitive taxa are lost over drying gradients, limiting the utility of current biomonitoring tools in IRES. To address this challenge, there is a need to evaluate which taxa should be used to calculate biomonitoring metrics and indicators over the different portions of the drying gradient. Here, using high-resolution drying data from 33 unpolluted streams, we explored the drying preferences of macroinvertebrates to identify their potential as biomonitoring indicators in IRES. To do this, we characterized macroinvertebrate drying niches and identified those with drying resistance and sensitivity preferences. Next, we evaluated the capacity of functional traits to predict drying specialization and affinity. Finally, to identify potential biomonitoring metrics and indicators for IRES, we evaluated how drying influenced the density, relative abundance and richness of taxa in drying sensitive and drying-resistant niches. Our results identified three macroinvertebrate groups with drying resistant niches (partly tolerant, generalist and specialist taxa) and one group of drying-sensitive taxa. We also found that functional traits had a limited capacity to represent differences in drying niches, with shredding trophic preferences and body size showing the strongest correlations. In addition, we observed that the density, relative abundance and richness of drying-resistant taxa were less influenced by drying intensity than those of drying-sensitive taxa. Finally, we found that some pollution-sensitive taxa with partial (e.g., Lepidostoma), moderate (e.g., Corduliidae) or high drying tolerance (e.g., Nemoura) can serve as potential indicators in IRES. Taken together, our results demonstrate that characterizing drying niches can be a useful strategy for developing biomonitoring tools in IRES and for highlighting the limitations of taxonomic and trait-based approaches