Papers by Pilar Lopez Laseras
SE HA ESTUDIADO LA COMPOSICION QUIMICA DEL AGUA-COMPUESTOS MAYORITARIOS Y NUTRIENNES- EN 56 LAGUN... more SE HA ESTUDIADO LA COMPOSICION QUIMICA DEL AGUA-COMPUESTOS MAYORITARIOS Y NUTRIENNES- EN 56 LAGUNAS SALOBRE E HIPERSALADAS DE LA ZONA MEDITERRANEA Y LA COMPOSICION DEL SEDIMENTO -CALCIO METALES Y FOSFORO- EN 15 DE ELLOS. SE DESCRIBE TAMBIEN LA VARIACION ANUAL DE LOS PARAMETROS QUIMICO EN DOS LAGUNAS: UNA LAGUNA COSTERA -LA MASSONA Y UN LAGO SALADO INTERIOR -GALLOCANTA. SE OBSERVAN MODIFICACIONES DE LOS EQUILIBRIOS IONICOS (COCIENTES C1/SO4 Y N/P) CAUSADAS POR MEZCLA CON AGUA MARINA EXCESO DE EVAPORACION Y EFECTO DE LA ACTIVIDAD DE LOS ORGANISMOS. ASIMISMO EL INTERCAMBIO ENTRE AGUA Y SEDIMENTO REGULA LA COMPOSICION QUIMICA. LA EXISTENCIA DE GRADIENTES REDOX ASOCIADOS O NO A PICNOCLINAS MODIFICA MUCHOS CICLOS BIOGEOQUIMICOS IMPORTANTES COMO EL DEL CARBONO FOSFORO AZUFRE HIERRO Y MANGANESO. LA COMPOSICION QUIMICA DE LAS AGUAS AFECTA CONSIDERABLEMENTE A LA COMPOSICION Y DIVERSIDAD DE LAS PROBLACIONES DE ORGANISMOS AL MISMO TIEMPO QUE ES REGULADA POR ELLAS.
Science of The Total Environment, 2019
The microbial decomposition of organic matter is a fundamental ecosystem process that transforms ... more The microbial decomposition of organic matter is a fundamental ecosystem process that transforms organic matter and fuels detritus-based food webs, influencing biogeochemical cycles such as C-cycling. The efficiency of this process can be compromised during the non-flow periods of intermittent and ephemeral streams (IRES). When water flow ceases, sediments represent the last wet habitat available to microorganisms and may play an important role in sustaining microbial decomposition. However, despite the increasing prevalence of IRES due to climate change and water abstraction, it is unclear to what degree the subsurface habitat can sustain microbial decomposition during non-flow periods. In order to gather information, we selected 20 streams across Catalonia (Spain) along a gradient of flow intermittency, where we measured microbial decomposition and fungal biomass by placing wood sticks in both the surface and subsurface zones (15 cm below the streambed) over the course of one hydrological year. Our results showed that microbial decomposition and fungal biomass were consistently greater in the subsurface zone than in the surface zone, when intermittency increased. Although flow intermittency was the main driver of both microbial decomposition and fungal biomass, phosphorus availability in the water, sediment C:N ratio and sediment grain size also played relevant roles in surface and subsurface organic matter processing. Thus, our findings demonstrate that although the OM processing in both zones decreases with increased intermittency, the subsurface zone made an important contribution during the non-flow periods in IRES. Therefore, subsurface activity during non-flow periods has the potential to affect and maintain ecosystem functioning.
Butlleti De La Institucio Catalana D Historia Natural, 1986
Es presenten els resultats d'una investigacio preliminar de la composicio quimica dels sediments ... more Es presenten els resultats d'una investigacio preliminar de la composicio quimica dels sediments de la Massona, una Ilacuna costanera dels aiguamolls de I'Emporda. Hom hi va analitzar el calci, ferro, manganes, fosfor, plom i crom. Els valors observats concorden amb estudis previs de les caracteristiques de les aigues. L'hipolimnion anoxic de la Ilacuna fa que en el sediment hi hagi un empobriment relatiu en calci (concentracio mitjana, 79,9 mg/g), manganes (concentracio mitjana, 286 ppm) i fosfor (concentracio mitjana, 752 ppm) , mentre que el ferro i el crom hi son augmentats (concentracions mitjanes del 39,1°/'°i de 58,7 ppm, respectivament). Els perfils verticals del ferro i del manganes son oposats: el ferro augmenta en profunditat 1 el manganes disminueix. Ambdos elements presenten entre ells una correlacio negativa (r=-0,50). Aquests resultats indiquen que les condicions redu'ides en el fons d'aquesta Ilacuna son relativament constants, i que en el passat hi ha hagut un canvi en les entrades, probablement degut a una menor influencia de I'aigua de mar. SUMMARY Calcium , phosphorus and metals in the sediment of La Massona lagoon (Girona , Spain) This paper reports the results of an exploratory investigation of the chemical composition of sediments from La Massona, a coastal lagoon located in the Aiguamolls de I'Emporda area (salt marshes in Girona, Spain). Calcium, iron, manganese, phosphorus, lead and chromium were analized. The observed values were consistent with previous studies of water characteristics. Anoxic hypolimnion in the lagoon caused a relative impoverishment of the sediment in calcium (mean concentration, 79.9 mg/g), manganese (mean concentration, 286 ppm) and phosphorus (mean concentration, 752 ppm), whereas iron and chromium increased (mean concentrations, 3.91 % and 58.7 ppm respectively). Iron and manganese vertical profiles were
Homage to Ramon Margalef or Why There Is Such Pleasure in Studying Nature 1992 Isbn 84 475 0019 5 Pags 113 125, 1992
Sedimentary phosphorus dynamics being a very complex process involving a large number of differen... more Sedimentary phosphorus dynamics being a very complex process involving a large number of different mechanisms, literature data present a wide range of variations both from the quantitative and from the qualitative point of view. Three main aspects are considered in this paper: the range of sedimentary phosphorus observed in lakes worldwide and relationships with other lake characteristics such as trophic status, depth, sedimentary iron and organic matter; phosphorus release rates and factors controlling them, and forms in which phosphorus is bound in sediments and their ecological significance. Because of the complexity of the mechanisms involved, no general concJusions valid for any kind of lakes may be drawn on the basis of the information now available.
L’objectiu de l’Ecologia de segon curs de llicenciatura de Biologia és entendre com les relacions... more L’objectiu de l’Ecologia de segon curs de llicenciatura de Biologia és entendre com les relacions de les espècies entre elles i amb les condicions ambientals existents expliquen certes regularitats en la distribució i l’abundància dels individus de les diverses espècies. L’aproximació d’aquestes pràctiques és procurar una descripció abreujada i explicativa del conjunt d’espècies que coexisteixen en una comunitat natural. Les pràctiques consten, d’una banda, de mostreig de camp, que queda reflectit als capítols I, II i VII, i de l’altra el tractament posterior de les dades recollides, al laboratori de càlcul de la Facultat de Biologia. La zona d’estudi escollida és la zona de platja anomenada Els Muntanyans de Torredembarra (Tarragona), àrea protegida amb vegetació pròpia de sistemes costaners dunars i salats. A partir de les dades de camp s’estudien els diferents tipus de comunitats que s’observen a partir de la classificació d’inventaris (capítol III), el pes dels factors ambiental...
Wetlands, 2008
In the Neotropics, differences in phytogeographic patterns and species richness respond nonrandom... more In the Neotropics, differences in phytogeographic patterns and species richness respond nonrandomly to edaphic factors in many upland forests. However, whether wetland forests follow the same species differentiation patterns is not well known. In this paper we analyze the relationship among species occurrences and selected soil characteristics, particularly salinity and acidity, in several wetland plant communities. Plant specimens were collected and soil samples analyzed for exchangeable cations, chloride, and organic carbon. Statistical methods were applied to assess b-diversity and to detect relationships between patterns of floristic variation and spatial variations of the soil conditions. bdiversity was high among vegetation communities. Edaphic conditions were heterogeneous, and landward gradients were present only for salinity and some exchangeable bases. This resulted in a lack of a straightforward relationship of vegetation patterns to salinity. More than 30% of the reported species covaried with at least one of the three acidity-related variables, suggesting that some tolerance to deleterious effects of H + and Al 3+ at pH values , 4 is likely. Thus, in contrast to what we might expect in deltaic regions, acidity rather than salinity was the major factor driving species organization. However, variation of these soil characteristics taken together accounted for only 40% of floristic differences among communities.
Freshwater Biology, 2018
1. Spatial and temporal widening of drought periods together with occurrence of flash storm event... more 1. Spatial and temporal widening of drought periods together with occurrence of flash storm events are consequences of global change affecting temporary stream ecosystems. Streambed heterotrophic microbes and the key biogeochemical processes they carry on could be endangered by the strengthening of drought episodes. 2. Here, we performed a 165-day experiment through 12 streambed sediment columns to study heterotrophic microbial functional and structural responses to long-term drought. Two sediment depths (surface and hyporheic) and leaf litter were monitored under three treatments: control (maintained in wet, pool-like conditions), dry (5 months of drought), and dry-storm (5 months of drought including two flash storms). All treatments were then followed by rewetting. 3. Surface sediment followed by leaf litter was the most affected by the long-term drought as shown by the reduction of polysaccharidic enzyme activities and litter decomposition rate, although lignin decomposition was not affected. This resulted in a greater use of recalcitrant compounds which might be due to reduced labile organic matter sources and the greater resistance of fungi than bacteria to drought. Moreover, in surface sediment, bacterial viability and algal biomass were reduced while the production of extracellular polymeric substances was intensified with dryness, suggesting its potential role as survival strategy. 4. Hyporheic sediments appeared more resistant to long-term drought, and this might be linked to its slightly higher water content (2.5%) than the surface (0.5%) during drying together with a greater content of fine material that allowed fungi and bacteria to survive and extracellular enzyme activities to be maintained. 5. Microbial resilience to long-term drought in sediment and leaf litter was promoted by the flash storms as shown by the fast recovery of enzyme activities, bacterial viability and leaf litter decomposition rate in the dry-storm treatment, once rewetted. Storms might liberate previously occluded carbon sources that fuel the fast microbial reactivation as well as providing sediment moisture for microbial survival. 6. Our results highlight that long-term drought may compromise stream biogeochemical processes linked to organic matter decomposition and that microbes are highly sensitive to minimal water content changes. Thus, long-term drought con-| 307 GIONCHETTA ET Al.
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Papers by Pilar Lopez Laseras