| 1. |
- Catalan, Nuria, et al.
(författare)
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Carbon dioxide efflux during the flooding phase of temporary ponds
- 2014
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Ingår i: LIMNETICA. - 0213-8409. ; 33:2, s. 349-359
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Tidskriftsartikel (refereegranskat)abstract
- Small water bodies, such as temporary ponds, have a high carbon processing potential. Nevertheless, despite the global occurrence of these systems, the carbon effluxes from such water bodies have been largely overlooked. In this study, we examined the intra- and intersystem variability of carbon dioxide (CO2) effluxes from a set of Mediterranean temporary ponds during the flooding phase, a hot-spot for biogeochemical cycling in temporary systems. The CO2 effluxes showed higher variability among the various sections of each pond (i.e., inundated, emerged-unvegetated and emerged-vegetated) than among the ponds. The emerged-vegetated sections showed the highest CO2 effluxes per unit area and tended to drive the total effluxes at the whole-ecosystem scale. The mean CO2 efflux (121.3 +/- 138.1 mmol m(-2) d(-1)) was in the upper range for freshwater ecosystems. The CO2 effluxes were not related to catchment properties but rather to the organic content of the sediments, especially in the emerged sections of the ponds. Our results indicate that temporary ponds, especially their emerged sections, are important sources of CO2 to the atmosphere, highlighting the need to include the dry phases of these and other temporary aquatic systems in regional carbon budgets.
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| 2. |
- Ecke, Frauke
(författare)
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Compositional breakpoints of freshwater plant communities across continents
- 2023
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Ingår i: Limnetica. - : Asociacion Iberica de Limnologia. - 0213-8409. ; 42, s. 291-301
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Konferensbidrag (refereegranskat)abstract
- Unravelling patterns and mechanisms of biogeographical transitions is crucial if we are to understand compositional gradients at large spatial extents, but no studies have thus far examined breakpoints in community composition of freshwater plants across continents. Using a dataset of almost 500 observations of lake plant community composition from six continents, we examined, for the first time, if such breakpoints in geographical space exist for freshwater plants and how well a suite of ecological factors (including climatic and local environmental variables) can explain transitions in community composition from the subtropics to the poles. Our combination of multivariate regression tree (MRT) analysis and k-means partitioning suggests that the most abrupt breakpoint exists between temperate to boreal regions on the one hand and freshwater plant communities harbouring mainly subtropical or Mediterranean assemblages on the other. The spatially structured variation in current climatic conditions is the most likely candidate for controlling these latitudinal patterns, although one cannot rule out joint effects of eco-evolutiona-ry constraints in the harsher high-latitude environments and post-glacial migration lags after Pleistocene Ice Ages. Overall, our study supports the foundations of global regionalisation for freshwater plants and anticipates further biogeographical research on freshwater plant communities once datasets have been harmonised for conducting large-scale spatial analyses.
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| 3. |
- Lupon, Anna
(författare)
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The influence of Mediterranean riparian forests on stream nitrogen dynamics: a review from a catchment perspective
- 2017
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Ingår i: Limnetica. - : Asociacion Iberica de Limnologia. - 0213-8409 .- 1989-1806. ; 36, s. 507-523
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Tidskriftsartikel (refereegranskat)abstract
- Riparian zones are considered natural filters of nitrogen (N) within catchments because they can substantially diminish the exports of N from terrestrial to aquatic ecosystems. However, understanding the influence of riparian zones on regulating N exports at the catchment scale still remains a big challenge in ecology, mainly because upscaling plot scale results is difficult, as it is disentangling the effects of riparian, upland, and in-stream processes on stream water chemistry. In this review, we summarize previous studies examining key hydrological and biogeochemical processes by which Mediterranean riparian zones regulate catchment water and N exports. We focus on Mediterranean regions because they experience a marked climatic seasonality that facilitates disentangling the close link between climate, riparian hydrology, and stream N exports. We show that Mediterranean riparian soils can be hot spots of N mineralization and nitrification within catchments given their relatively moist conditions and large stocks of N-rich leaf litter. Extremely large nitrification rates can occur during short-time periods (i.e. hot moments) and lead to increases in stream N loads, suggesting that riparian soils can be a potential source of N to adjacent aquatic systems. Moreover, riparian trees can contribute to decrease riparian groundwater level during the vegetative period, and promote reverse fluxes from the stream to the riparian zone. During periods of high hydrological retention, stream water exports to downstream ecosystem decrease, while stream water chemistry is mostly determined by in-stream processes. Riparian tree phenology can also affect catchment N exports by shaping the temporal pattern of both light and litter inputs into the stream. In spring, light enhances in-stream photoautotrophic N uptake before riparian leaf-out, while riparian leaf litter inputs promote in-stream N mineralization in summer and fall. Finally, we illustrate that the impact of Mediterranean riparian zones on stream hydrology and biogeochemistry increases along the stream continuum, and can ultimately influence catchment N exports to downstream ecosystems. Overall, findings gathered in this review question the well-established idea that riparian zones are efficient N buffers, at least for Mediterranean regions, and stress that an integrated view of upland, riparian, and stream ecosystems is essential for advancing our understanding of catchment hydrology and biogeochemistry.
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| 4. |
- Pastor, Ada, et al.
(författare)
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Local and regional drivers of headwater streams metabolism : insights from the first AIL collaborative project
- 2017
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Ingår i: LIMNETICA. - : Asociacion Iberica de Limnologia. - 0213-8409 .- 1989-1806. ; 36:1, s. 67-85
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Tidskriftsartikel (refereegranskat)abstract
- Streams play a key role in the global biogeochemical cycles, processing material from adjacent terrestrial systems and transporting it downstream. However, the drivers of stream metabolism, especially those acting at broad spatial scales, are still not well understood. Moreover, stream metabolism can be affected by hydrological changes associated with seasonality, and thus, assessing the temporality of metabolic rates is a key question to understand stream function. This study aims to analyse the geographical and temporal patterns in stream metabolism and to identify the main drivers regulating the whole ecosystem metabolic rates at local and regional scales. Using a coordinated distributed experiment, we studied ten headwaters streams located across five European ecoregions during summer and fall 2014. We characterized the magnitude and variability of gross primary production (GPP) and ecosystem respiration (ER) with the open-channel method. Moreover, we examined several climatic, geographical, hydrological, morphological, and physicochemical variables that can potentially control stream metabolic rates. Daily rates of stream metabolism varied considerately across streams, with GPP and ER ranging from 0.06 to 4.33 g O-2 m(-2) d(-1) and from 0.72 to 14.20 g O-2 m(-2) d(-1), respectively. All streams were highly heterotrophic (P/R < 1), except the southernmost one. We found that the drier climates tended to have the highest GPP, while humid regions presented the highest ER. Between the sampling periods no statistical differences were found. Partial-least squares models (PLS) explained similar to 80% of the variance in GPP and ER rates across headwater streams and included both local and regional variables. Rates of GPP varied primarily in response to the local variables, such as streambed substrate and stream water temperature. In contrast, regional variables, such as the mean annual temperature or the land use of the catchment, had more relevance to explain ER. Overall, our results highlight that stream metabolism depends on both local and regional drivers and show the positive experience of a young network of researchers to assess scientific challenges across large-scale geographic areas.
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| 5. |
- Sanchez-Montoya, Maria Mar, et al.
(författare)
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Women in limnology in the Iberian Peninsula : biases, barriers and recommendations
- 2016
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Ingår i: LIMNETICA. - 0213-8409. ; 35:1, s. 61-72
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Tidskriftsartikel (refereegranskat)abstract
- Gender biases in science have received increasing attention in recent years. Underrepresentation at the highest academic levels and bias in publication are some of the factors affecting women in science. In this study, we assessed the situation of women in Limnology, a specific field of natural sciences, within the geographic context of the Iberian Peninsula. We used a multi-faceted approach to diagnose the situation, and we propose guidelines to reduce gender gaps in Limnology. The database of members of the Iberian Limological Association (AIL) was used to analyse the. variability between genders at different professional stages. Data was also compiled on plenary speakers who attended conferences organized by different associations (AIL, SEFS and ASLO) to assess women's visibility. A published data set was used to identify leadership patterns in publications with respect to gender. Finally, a survey of AIL members was conducted to understand their perception of the barriers in science that result in differences between the genders. This study recognized differences at the recruitment level (more tenured positions are held by men), visibility at conferences (fewer women are invited as plenary speakers) and publication as team leaders (men have more publications as first and last authors). Survey participants recognised the scarcity of grants/funding, difficulties in balancing life and career, and the scarcity of job opportunities as the three main barriers in science, regardless of gender. Yet, women identified family-related barriers such as having children and gender biases more frequently. Overall, our study indicates that there is a general gender bias in the field of Limnology in the Iberian Peninsula; however, it is slightly lower than the reported levels in Europe and for other disciplines in Spain. Finally, we provide a list of recommendations to balance the current biases based on suggestions made by the participants of a round table held at the XVII Congress of the AIL (Santander, July 2014). We encourage associations in natural sciences and the AIL in particular to use this study as a guideline for best practices as well as a baseline for future analysis of gender biases.
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| 6. |
- Trigal, Cristina
(författare)
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Proposal of a typology of Spanish mountain lakes and ponds using the composition of functional groups of macrophytes
- 2015
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Ingår i: Limnetica. - 0213-8409. ; 34, s. 507-525
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Tidskriftsartikel (refereegranskat)abstract
- Before establishing the ecological status of lakes, the Water Framework Directive requires their classification in types. Typically, the development of a typology has been based on abiotic variables. However, for the typology to have validity, the classification of lakes should be corroborated with the biological communities in the bodies of water. In this study, to develop a biologically relevant typology, the natural variability of the macrophyte communities in mountain lakes and ponds was evaluated. The use of functional groups of macrophytes as an alternative to the taxonomic approach was also evaluated. Thirty-one reference mountain lakes and ponds, located in the northwest quadrant of the Iberian Peninsula, were included in the study. The functional groups of macrophytes were based on the inorganic source of carbon used in photosynthesis. The typology developed from the functional groups was more conclusive than the classification derived from the taxonomic data. The primary determinants of the variability in the composition of the functional groups of macrophytes among the different types of lakes were the changes in the pH and in the orthophosphate concentration related to the decomposition of macrophytes. The submerged macrophytes dominated in the lakes with low concentrations of orthophosphate and the highest levels of alkalinity. In the lakes with lower pH values, the floating-leaved macrophytes were the dominant plants when the phosphorus concentration was higher, whereas at intermediate concentrations of phosphorus, the bryophytes and isoetids were more abundant; these two lake types were differentiated because of the dominance of the bryophytes in those lakes with higher acidity.
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| 7. |
- Williams, Clayton J., et al.
(författare)
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Add a dash of salt? Effects of road de-icing salt (NaCl) on benthic respiration and nutrient fluxes in freshwater sediments : [¿Agregar una pizca de sal? Efectos de la sal usada en carreteras (NaCl) sobre la respiración béntónica y los flujos de nutrientes en los sedimentos de agua dulce]
- 2023
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Ingår i: Limnetica. - : Asociación Ibérica de Limnología. - 0213-8409. ; 42:2, s. 233-250
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Tidskriftsartikel (refereegranskat)abstract
- Winter road salt applications are increasing chloride concentrations in many freshwater ecosystems. This trend is alarming, given chloride’s potential to impair aquatic ecosystems. Short- and long-term exposure to salt could affect ecosystem metabolism and nutrient cycles. Here, we examine connections between chloride concentrations, water quality conditions, benthic respiration, and sediment-water nutrient flux throughout a large (722 km2) lake and its catchment. Aquatic locations experiencing high concentrations of chloride are indicators of anthropogenic activities and are often associated with additional pollutants. We used sediment core flow-through incubations under ambient and enriched chloride concentrations to determine the effects of road salt on benthic respiration and nutrient fluxes in stream, stormwater pond, and lake sites. Salt (as sodium chloride) additions caused a significant overall increase in benthic respiration. Acute exposure to road salt caused the strongest increase in benthic respiration when water was warm and at sites that had low (< 50 mg Cl-/L) or high (> 400 mg Cl-/L) ambient chloride concentrations or when water was cold and sites had intermediate (100-400 mg Cl-/L) ambient chloride concentrations. Nitrate flux responded less uniformly to salt additions. Depending on waterbody type and season, ambient nitrate flux into the sediment was similar, increased, or decreased post-chloride addition. Dissolved phosphorus flux was not significantly impacted by salt additions. Across lake and stream sites, our results supported the hypothesis that chloride causes increased respiration while nutrient cycles were weakly and inconsistently altered under experimental pulse road salt additions.
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