CSIC Institute of Natural Resources

Madrid, Spain

CSIC Institute of Natural Resources

Madrid, Spain
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Angeler D.G.,Swedish University of Agricultural Sciences | Alvarez-Cobelas M.,CSIC Institute of Natural Resources | Rojo C.,University of Valencia | Sanchez-Carrillo S.,CSIC Institute of Natural Resources
Ecological Research | Year: 2010

In this study we compare phytoplankton community similarity between sites in a semiarid floodplain wetland over a 6-year period with variable hydroperiod and connectivity regimes. Phytoplankton communities showed a relatively high site idiosyncrasy during most parts of the study; however, during situations of low connectivity when individual sites were highly fragmented, phytoplankton communities occasionally became more similar between sites. This suggests that mass effects related to dispersal-mediated processes could be important. Viewed from a metacommunity perspective, phytoplankton community assembly at the wetland scale involves complex hierarchical processes that can act independently at different spatial extents. The main conclusion of this study is that the well-known effects of environmental variability associated with hydrological disturbance alone may not be sufficient for explaining, and by extension predicting, community assembly in this wetland. Other processes, perhaps involving overland dispersal, may eventually add a new dimension to, and complicate our understanding of, community processes in fluctuating wetlands. © 2010 The Ecological Society of Japan.

Alvarez-Cobelas M.,CSIC Institute of Natural Resources | Sanchez-Andres R.,CSIC Royal Botanical Garden of Madrid | Sanchez-Carrillo S.,CSIC Institute of Natural Resources | Angeler D.G.,Swedish University of Agricultural Sciences
Journal of Arid Environments | Year: 2010

Thirty five catchments in semiarid Central Spain were monitored monthly in late winter and spring to search for relationships between environmental variables (sedimentary nutrients and hydrological topographical, geological, pedological, land use factors) and nutrient concentrations and exports. Results enabled to outline differences between semiarid and moist catchments, the latter drawn from other studies. While land use, topography and ecotone features explained an important fraction of overall variance of nutrients in moist areas, geological and pedological features were much better descriptors in semiarid catchments. Runoff explained most variability of total carbon, organic carbon and nitrogen export, and soil types and carbon and phosphorus contents stored in stream sediments best explained total phosphorus, dissolved- and particulate organic carbon export in semiarid catchments. In moist catchments geology, climate, pedology and land use were shown to influence nutrient export. Hydrology potentially swamped effects related to land use and landscape structure (i.e. topographical, geological and soil factors). Thus nutrient concentration and export in semiarid catchments deviate from those in moist catchments which is due to the overriding effects of hydrological features, geology and pedology. Further research, including the application of combined GIS techniques and modeling approaches, is needed to generalize our findings over other semiarid areas. © 2010 Elsevier Ltd. All rights reserved.

Benitez-Gilabert M.,CSIC Institute of Natural Resources | Alvarez-Cobelas M.,CSIC Institute of Natural Resources | Angeler D.G.,Swedish University of Agricultural Sciences | Angeler D.G.,University of Castilla - La Mancha
Climatic Change | Year: 2010

There is unequivocal evidence of increased air temperatures in Spain as a result of climate change. Using organic matter, nitrate and soluble reactive phosphorus concentrations, we reconstructed changes in water quality in 15 montane, pristine streams between 1973 and 2005 in Spain. We also measured how loading rates of these variables change as a function of shifting temperatures. Almost half of tested variables were related with hypothesized trends of climatic change for air temperature. Concerning extreme events, the hypothesis of climatic change matched in 33% of all relationships, which mostly occurred in Northern Spain. Regional gradients of population change and soil degradation, however, did not explain the geographical distribution of climatic change effects. The main reason that effects on water quality are not ubiquitous and that constraining factors are hardly detected may be that long-term signals are the outcome of several interacting processes. These are still poorly known and may act at different spatial and temporal scales. Hence, a case-by-case approach might prove more fruitful than a regional one when studying water quality responses to climatic change. Consideration of the balance between extreme and normal events (storm-vs baseflow), catchment effects (land use and its effects on evapotranspiration and runoff) and in-stream processes (outgassing, mineralization, burial) could help increase our understanding of the responses of water quality to climatic change. © 2009 Springer Science+Business Media B.V.

Angeler D.G.,Swedish University of Agricultural Sciences | Angeler D.G.,University of Castilla - La Mancha | Alvarez-Cobelas M.,CSIC Institute of Natural Resources | Sanchez-Carrillo S.,CSIC Institute of Natural Resources
Ecological Indicators | Year: 2010

In this study we evaluated the usefulness of rotifer emergence from dry soils to indicate the environmental status of a remnant temporary pond complex in an agricultural area in central Spain. Because the ponds did not flood during our project, emergence was studied in relation to environmental variables in outdoor microcosms. Redundancy analysis and nestedness analysis showed that salinity and total nitrogen concentrations shaped the emerged communities. Depauperate rotifer assemblages from pond microcosms with higher salinity and nitrogen levels were nested subsets of species-rich communities from microcosms of less enriched sites. Rotifer community structure also identified small ponds as reference sites that should receive priority in conservation and degradation mitigation programs. Results suggest that rotifer emergence from rewetted sediments using microcosms can be useful for evaluating the nutrient status during the dry phase of temporary wetlands. While results from this approach are conservative, requiring comparisons with field observations, their tentative value lies in alerting management and providing a basis for future research of poorly studied but threatened temporary habitats. Rotifer emergence could be a useful alternative to traditional biological indicators of nutrient status that depend on the presence of water. © 2009 Elsevier Ltd. All rights reserved.

Alvarez-Cobelas M.,CSIC Institute of Natural Resources | Angeler D.G.,Swedish University of Agricultural Sciences | Sanchez-Carrillo S.,CSIC Institute of Natural Resources | Almendros G.,CSIC Institute of Natural Resources
Biogeochemistry | Year: 2012

Growing interest in the effects of global change on the metabolism, stoichiometry and cycling of carbon in aquatic ecosystems has motivated research on the export of organic carbon (OCE) from catchments. In this article, quantitative and functional features of the annual export rates of total, particulate and dissolved organic carbon (TOC, POC and DOC) were reviewed, and the stoichiometry of export (OC:N, OC:P and N:P) from 550 catchments worldwide was reported. TOC export ranged 2.1-92,474 kg C km -2 year -1, POC export ranged 0. 4-73,979 kg C km -2 year -1 and DOC export ranged 1.2-56,946 kg C km -2 year -1. Exports of TOC and DOC were strongly linked, but POC export was unrelated to DOC. The DOC fraction comprised on average 73 ± 21% of TOC export. The export rates of organic carbon were poorly related to those of total nitrogen and total phosphorus. Discrete and continuous environmental variables failed to predict TOC export, but DOC export was influenced by discharge and catchment area worldwide. Models of OCE in different catchment types were controlled by different environmental variables; hydrological variables were generally better predictors of OCE than anthropogenic and soil variables. Elemental ratios of carbon export in most catchments were above the Redfield ratio, suggesting that phosphorus may become the limiting nutrient for downstream plant growth. These ratios were marginally related to environmental data. More detailed hydrological data, consideration of in-stream processes and the use of quasi-empirical dynamical models are advocated to improve our knowledge of OCE rates and those of other nutrients. © 2010 Springer Science+Business Media B.V.

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