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The metacommunity concept provides a theoretical framework that aims at explaining organism distributions by a combination of environmental filtering, dispersal, and drift. However, few works have attempted a multitaxon approach and even fewer have compared two distant biogeographical regions using the same methodology. We tested the expectation that temperate (mediterranean-climate) pond metacommunities would be more influenced by environmental and spatial processes than tropical ones, because of stronger environmental gradients and a greater isolation of waterbodies. However, the pattern should be different among groups of organisms depending on their dispersal abilities. We surveyed 30 tropical and 32 mediterranean temporary ponds from Costa Rica and Spain, respectively, and obtained data on 49 environmental variables. We characterized the biological communities of bacteria and archaea (from the water column and the sediments), phytoplankton, zooplankton, benthic invertebrates, amphibians and birds, and estimated the relative role of space and environment on metacommunity organization for each group and region, by means of variation partitioning using generalized additive models. Purely environmental effects were important in both tropical and mediterranean ponds, but stronger in the latter, probably due to their larger limnological heterogeneity. Spatially correlated environment and pure spatial effects were greater in the tropics, related to higher climatic heterogeneity and dispersal processes (e.g., restriction, surplus) acting at different scales. The variability between taxonomic groups in the contribution of spatial and environmental factors to metacommunity variation was very wide, but higher in active, compared with passive, dispersers. Higher environmental effects were observed in mediterranean passive dispersers, and higher spatial effects in tropical passive dispersers. The unexplained variation was larger in the tropical setting, suggesting a higher role for stochastic processes, unmeasured environmental factors, or biotic interactions in the tropics, although this difference affected some actively dispersing groups (insects and birds) more than passive dispersers. These results, despite our limitations in comparing only two regions, provide support, for a wide variety of aquatic organisms, for the classic view of stronger abiotic niche constraints in temperate areas compared with the tropics. The heterogeneous response of taxonomic groups between regions also points to a stronger influence of regional context than organism adaptations on metacommunity organization.

Zooplankton community assembly after flooding in temporary ponds depends mostly on abundance and diversity of the dormant propagule bank. However, our understanding of the hatching patterns of zooplankton is imperfect. We performed an ex situ experiment to study the species composition and temporal sequence of zooplankton emergence from sediments in three ponds that were restored at different times: 1998, 2003 and 2007. The patterns of species hatching observed in our microcosms were compared with the emergent zooplankton community of their equivalent, synchronically inundated ponds. An escalation in species richness and a delay in hatching time were detected with increasing restoration age. In addition, some discrepancies between the egg bank and active populations were observed, especially in the oldest pond. This study illustrates the use of hatching experiments in comparing ponds with different characteristics. Nevertheless, egg bank hatching and water column sampling should complement each other in order to afford a full reflection of past diversity and contribute to a better understanding of the efficiency of restoration practices.

Entre 2017 y 2018 se realizó un estudio limnológico de 30 lagunas temporales de Costa Rica. Entre otros organismos, se estudiaron las esponjas de agua dulce (Porifera: Spongillidae), en cuya distribución se centra el presente estudio. De las muestras se aislaron 15 552 gémulas de esponjas repartidas en 21 localidades de la provincia de Guanacaste. Este material se obtuvo a lo largo de seis campañas de muestreo efectuadas entre mayo de 2017 y diciembre de 2018. Las especies de esponjas identificadas fueron Radiospongilla crateriformis (Potts, 1882), Corvoheteromeyenia heterosclera (Ezcurra de Drago, 1974), Tubella variabilis Bonetto & Ezcurra de Drago, 1973 y Ephydatia fluviatilis (Linnaeus, 1759) con nuevas localidades. Se recolectaron las cuatro especies juntas en una laguna denominada “El Sitio” y se citan dos nuevas localidades de T. variabilis en “Sainalosa” y “El Sitio” junto con Ephydatia fluviatilis y Corvoheteromeyenia heterosclera en la primera, ambas lagunas localizadas en la provincia de Guanacaste. Además, destaca la recolección de gémulas de T. variabilis aglutinadas en el tubo de alojamiento del oligoqueto Aulophorus vagus Leidy, 1880 (Annelida: Oligochaeta: Naididae). Todas las gémulas se recolectaron únicamente en la vertiente Pacífica de Costa Rica, mientras que no se encontró ninguna en las lagunas muestreadas en la vertiente Atlántica, correspondiéndose con una mayor disponibilidad de fitoplancton en la primera, y mayor transparencia y menor concentración de sales del agua en la segunda.

Resumen La insuficiencia cardiaca es una enfermedad que precisa un tratamiento multidisciplinario, dadas la diversidad de causas y entornos clinicos implicados que las tratan y las diferentes estrategias terapeuticas que precisan la participacion indispensable de diversas disciplinas. La presencia en los servicios de cardiologia de unidades de insuficiencia cardiaca centradas en el tratamiento de los pacientes con esta afeccion y unidades de rehabilitacion cardiaca que, entre sus indicaciones para la reduccion de la morbimortalidad, tambien estan implicadas en la atencion de esos mismos pacientes puede causar dificultades de coordinacion y perdida de una atencion integral centrada en el paciente. Por estos motivos, en el presente documento se plantea una estrategia de coordinacion entre las diferentes unidades implicadas en el tratamiento de los pacientes dentro de los servicios de cardiologia y la continuidad asistencial con atencion primaria, tanto tras haber conseguido la estabilidad como la interrelacion para una coordinacion posterior mas efectiva.

The metacommunity concept provides a theoretical framework that aims at explaining organism distributions by a combination of environmental filtering, dispersal and drift. With the development of statistical tools to quantify and partially isolate the role of each of these processes, empirical metacommunity studies have multiplied worldwide. However, few works attempt a multi-taxon approach and even fewer compare two distant biogeographical regions using the same methodology. Under this framework, we tested the expectation that temperate (mediterranean-climate) pond metacommunities would be more influenced by environmental and spatial processes than tropical ones, because of stronger environmental gradients and greater isolation of waterbodies.We surveyed 30 tropical and 32 mediterranean temporary ponds from Costa Rica and Spain, respectively, and obtained data on 49 environmental variables (including limnological, hydrogeomorphological, biotic, climatic, and landscape variables). We characterized the biological communities of Bacteria and Archaea (from both the water column and the sediments), phytoplankton, zooplankton, benthic invertebrates, amphibians and birds, and estimated the relative role of space and environment on metacommunity organization for each group and region, by means of variation partitioning using Generalized Additive Models (GAMs).Environmental selection was important in both tropical and mediterranean ponds, but markedly stronger in the latter, probably due to their larger limnological heterogeneity. Spatialized environment and pure spatial effects were greater in the tropics, related to higher climatic heterogeneity and dispersal processes (e.g. restriction, surplus) acting at different scales. The variability between taxonomic groups in spatial and environmental contributions was very wide. Effects on passive and active dispersers were similar within regions but different across regions, with higher environmental effects in mediterranean active dispersers. The residual (unexplained) variation was larger in tropical pond metacommunities, suggesting a higher role for stochastic processes and/or effects of biotic interactions in the tropics. Overall, these results provide support, for a wide variety of organisms related to aquatic habitats, for the classical view of stronger abiotic niche constraints in temperate areas compared to the tropics.

Gambusia holbrooki es un pequeño pez Poecílido, de origen norteamericano que fue introducido a principios del siglo XX en humedales de la Península Ibérica para el control biológico de los mosquitos. Actualmente presenta poblaciones en muchos humedales y está considerada como una de las principales especies invasoras en la península. Estos peces se alimentan principalmente de invertebrados, pero son también susceptibles de ingerir y acumular residuos de microplásticos que presentan tamaños similares al tamaño de algunas de sus presas habituales. En el presente estudio analizamos los contenidos del tracto gastrointestinal de ejemplares adultos de esta especie, procedentes de dos lagunas costeras restauradas, con el objetivo de caracterizar la ingesta de microplásticos. Los restos de microplásticos encontrados fueron clasificados por tamaños, por categorías (fibras y fragmentos) y por colores. Se analizaron 156 ejemplares de Gambusia holbrooki: 92 hembras (59%) y 64 machos (41%). Las hembras presentaron un mayor peso (0.43 ± 0.31g) y longitud (3.42 ± 0.63 cm) que los machos (0.11 ± 0.03 g y 2.60 ± 0.26 cm). Un 44% de los peces presentó algún resto de microplástico (fibras o fragmentos) en el tracto gastrointestinal. La mayor parte de los microplásticos (48%) tenían un tamaño comprendido entre 100 y 400 µm. Las fibras azules fueron las más frecuentes (más del 60%), mientras que los fragmentos marrones fueron más abundantes (36%). En relación con el número medio de los microplásticos por individuo en los contenidos gastrointestinales, este fue ligeramente superior en machos respecto a las hembras, en muestras de primavera respecto a las de verano, y en la laguna G02 respecto a la L04, aunque únicamente se encontraron diferencias significativas entre las lagunas. Al analizar el número de microplásticos ingeridos en función del peso de los ejemplares de G. holbrooki, una ligera tendencia pone de manifiesto que los individuos con pesos inferiores presentaron mayor cantidad de microplásticos. En este sentido, la presencia de microplásticos en los contenidos gastrointestinales de peces puede ser un indicador del incremento de residuos de plásticos en ecosistemas costeros mediterráneos, pudiendo llegar a alterar las dinámicas tróficas de los organismos acuáticos.

Zooplankton abundance and composition is sensitive to eutrophication, and its top-down effect in the planktonic food web can alter the classification of the trophic state of waterbodies based on th...

Based on our results, we propose the use of zooplankton abundance (density or biomass) as an indicator to complement the information currently being used concerning the quality of water in reservoirs. Until now, the Water Framework Directive (EU) for lakes and reservoirs has not included zooplankton because the classification of the water trophic state is based on a bottom-up model: an increase in nutrients implies an increase in primary producers and, therefore, poorer water quality. The use of zooplankton has recently been claimed due to their sensitivity to environmental changes and their control over primary producers. From our work, carried out from 2006 to 2009 (summer and winter seasons) in 20 reservoirs found in various Mediterranean river basins, we prove the relationship of the abundance of zooplankton with the trophic state. Zooplankton abundance, with or without interaction with other agents, explained much of the distribution of total phosphorus in the reservoirs, thus relating the trophic status with the aquatic food chain. In addition, we have found, illustrated by the zooplankton: phytoplankton ratio, how the top-down control masked high production situations in the system. Zooplankton's ability to cover up these cases of poor water quality highlight that the indicators presently being used are frequently insufficient.

Animal vectors are essential for the movement of invertebrate resting eggs between water bodies. However, differences in habitat preferences and feeding behaviour between bird species may result in variations in the dispersal of invertebrates via these birds, even if the different bird species live in the same lake. To test such effects, faecal samples from Anas platyrhynchos (collected in autumn and spring) and Tadorna tadorna (collected in spring) were cultured in water at 20° C and 12 L: 12 D conditions in order to quantify the resting eggs which could be internally transported by these birds. One half of each faecal sample was initially cultured at a conductivity of 0.6 mS cm −1 and the other half at 6 mS cm −1 . 1054 invertebrates hatched from a total of 60 faecal samples, including cladocerans, copepods, ostracods, rotifers and ciliates, with a wide variability among faeces. Autumn yielded a low proportion of samples with hatchlings (12.5%) compared to spring (90%). Significant differences were observed between birds, but not between conductivity treatments. Thus, our results imply different hatching dynamics affected by disperser and season, but most species transported as resting eggs by birds seem to have a wide tolerance to hatch under variable salinity conditions. These differences may largery influence the metacommunity dynamics of lake networks, and could be a key factor to consider in wetland conservation planning.

Metacommunities are dynamic systems, but the influence of time independently of environmental change in their configuration has been rarely considered. Temporary ponds are excellent ecosystem models, as they have well-defined boundaries in time and space; their communities are relatively isolated through a landscape matrix, and the progress of time leads to major changes through ecological succession and in habitat suitability related to hydroperiod dynamics. Therefore, strong temporal effects are expected to influence their metacommunity structure. We surveyed 30 temporary ponds along the dry tropical region of western Costa Rica and Nicaragua at three different moments of their hydroperiod: shortly after the infilling of the water bodies, at the middle of the hydroperiod and just before desiccation. We obtained data on 56 environmental variables (including limnological, climatic, landscape, hydrogeomorphological and conservation state), and used geographic coordinates to build spatial variables (Moran Eigenvector Maps). We collected biological samples and estimated the specific abundance of phytoplankton, zooplankton and benthic invertebrates. To evaluate the relative role of environmental, spatial and temporal (sequential sampling season) effects in metacommunity organization of the 646 species found, we used variation partitioning with distance-based redundancy analyses for each group of organisms. We repeated the analyses for selected taxonomic groups, separately for each sampling season, to check how the variance explained by spatial and environmental factors varied between sampling periods. The inclusion of time in the analysis highlighted that pure temporal effects explained part of metacommunity variance in almost every group, being as important as spatial or even environmental effects for some groups of organisms. In contrast to the assumed low environmental constraints in tropical areas (i.e. high and stable temperatures), we found strong environmental effects. Passive dispersers were more influenced by environmental factors than active ones. We also found a positive relationship between the body size of the different groups of organism and the magnitude of the temporal effect, interpreted as related to generation time. Finally, when analyzing each sampling period separately, we found differences in the relative role of environment and space at different sampling periods, showing that snapshot surveys may not be representative of highly dynamic metacommunities.

Restoration is an ecological tool that aims to recover the prior conditions and functioning of a degraded habitat. Three restoration projects targeted a dune slack system in the Eastern Iberian Peninsula and created a mosaic of ponds restored over three different periods: 1998, 2003 and 2007, the latter coinciding with the start of our study. Restoration works consisted of digging out the pond basin to its original morphometry. We monitored 12 restored ponds (six recent, three intermediate and three older ones) monthly, over four consecutive hydrological years (from 2007 until 2011) characterizing the most important limnological factors in order to disentangle the effects of man-made restoration over time. A multivariate statistical approach was used to detect the environmental trends of these ponds related to their restoration ages. Recently restored ponds tended to converge with older ones by decreasing values of conductivity, pH, oxygen and depth and increasing vegetation cover over time. Detected differences seem to address age-specific processes which increase over time after restoration: silting, salt leaching or an increase in organic matter decomposition. These processes could strongly influence the community build-up and biodiversity therein.

Biomass and size-based estimations provide relevant information regarding ecosystem functioning and biotic interactions. Our aims were to study the effect of fish and macrophytes on the size structure of invertebrate assemblages (from rotifers to insects) in a set of coastal water bodies, estimating the biomass (total and main invertebrate groups), the biomass-size spectra (model of Pareto) and size diversity. In fishless ponds, cladoceran and ostracod biomass were higher, and they presented greater size diversity. In fish ponds, rotifer biomass presented greater proportion; while in fishless ponds, cladocerans were usually the most abundant taxa and the largest organisms. The biomass size spectra showed more irregularities in fishless ponds, due to the low densities of small taxa (rotifers and copepod juveniles) and big taxa (malacostraceans or insects). Differences is size structure and diversity were also observed between spring and summer, suggesting a higher recruitment of juveniles in spring, and thus, a higher predation pressure upon zooplankton at that moment. Macrophyte cover did not apparently influence those parameters, except for the biomass of ostracods, copepods, and insects. Therefore, predation by fish strongly affected invertebrate biomass, reflecting their selective feeding, and allowing high densities of small taxa. Predation pressure decreased size diversity, by limiting the abundance of vulnerable taxa of specific size. Seasonal changes were likely related to the spring recruitment of fish juveniles. The presence of small fish and invertebrate predator taxa among the macrophytes, restrict their role as refuges for prey invertebrates.

The toxicity of Bacillus thuringiensis var. israelensis on zooplanktonic microcrustaceans was evaluated using individuals collected in coastal wetlands where this larvicide has been used for mosquito control over the last decades. We tested five zooplankton species that coexist with mosquito larvae: two copepods (both nauplii and adults of Tropocyclops prasinus and Acantocyclops americanus), and three cladocerans (Ceriodaphnia reticulata, Chydorus sphaericus, and Daphnia cf. pulex). Our experiments included seven replicates of six concentrations (Bti Vectobac12AS 1200 Bti ITU/mg): 0, 5, 25, 50, 250, and 500 mg L−1. We analyzed acute and sub-chronic effects after a single inoculation. Despite the high variability of responses among our tested organisms, we found a general pattern of increasing mortality with concentration and time. We conclude that negative effects at the community level are not unlikely as some species were affected at doses close to those used in field applications.

Nutrients and carbon were studied in the temporary and permanent dune ponds of one of the few restored Mediterranean dune systems. The results indicate that small, low nutrient dune ponds can have a relevant role for carbon storage and processing, especially in the limestone areas. Despite the low percentage of organic matter in the sediment and water nutrient concentrations, most of the ponds had supersaturated carbon dioxide partial pressure levels with concentrations in half of them greater than the mean global value for lakes. Concentrations gradually decreased from old to newly restored ponds and with the presence of submerged plants. Carbon content was greater in temporary ponds. DOC was half of the mean global value for lakes. Particulate forms of nutrients and dissolved inorganic carbon predominated. Organic matter was a key variable for storage of nutrients and carbon in the sediment. Flooding of the ponds significantly reduced total organic carbon in the sediment by about 60%, but did not change significantly the concentrations of nitrogen and phosphorus. However, about 25% of organic matter and 37% of nitrogen accumulated in the sediment during consecutive summer droughts. Benthic algae incorporated part of the sediment nutrient pool after flooding.

Human-mediated dispersal has rarely been considered in wetland conservation strategies at regional scales, yet high concern exists about this aspect for (inter-)national management considering invasive species in other aquatic systems. In this context, we aim at understanding the role of human-mediated dispersal by footwear in protected wetlands with high conservation value. Zooplankton and zoobenthos were sampled in 13 shallow lakes in central Spain and, at the same time, mud attached to waders was collected and later cultured in deionized water under laboratory conditions for 4 weeks. Two-hundred and four individuals belonging to 19 invertebrate taxa were recovered after hatching; Ostracoda (84 %), Cladocera (53 %), Copepoda (30 %), Anostraca (30 %), and Notostraca (7 %) were the most frequent groups among the hatched crustaceans. NMDS and PERMANOVA analyses showed significant differences between the dispersed (via footwear) and the source active metacommunity, suggesting different dispersal abilities among the species found. Human vectors facilitate dispersal among protected lakes, which could eventuality lead to biotic homogenization and faster spread of non-indigenous species. Preservation strategies and education campaigns associated to target humans in close contact with water bodies should be imperative in conservation management of protected lakes.

Malladas de El Saler is a mosaic of dune slacks scattered along a coastal sand bar in the Mediterranean region. Active populations of the fairy shrimp T. stagnalis are exclusively present in one of these ponds. We combined field observations and laboratory experiments to find the ecological requirements of T. stagnalis that determine this habitat exclusiveness and the possibility of future establishment in nearby ponds. Conductivity revealed as a determinant ecological constraint. In the field, the species was restricted to conductivity levels below 1.28 mS cm−1 and in experimental microcosms, hatchability, survival and reproductive potential were detrimental from 2.9 mS cm−1. The observation of life history characteristics from the experimental individuals confirmed the importance of the unpredictable character of Mediterranean temporary ponds in shaping life history strategies, as they hatched early, matured rapidly and produced a high number of cysts. We discuss the essential steps during colonization that may explain the presence or absence in our ponds, and revealed a harsh future for the species if the current conditions of habitat deterioration persist. We suggest several conservation measures, including a cyst bank storage or/and adult translocations to nearby suitable ponds. These measures will ensure (1) the preservation of genetic diversity and (2) healthy metapopulation dynamics with recolonization rates compensating for local extinctions.

Invertebrate aquatic assemblages in ponds from Mediterranean wetlands are composed of organisms belonging to different taxonomic groups, which present a wide range of sizes (from small rotifers to large crustaceans or insects). Although they are often sampled and analyzed separately, the ecological links among these organisms should be considered, especially in very shallow waters. In our study, invertebrate assemblages (including micro-, macrozooplankton and macroinvertebrates) were characterized in eight shal- low lakes from Mediterranean wetlands in Southeastern Spain. A great spatial and temporal variability in the assemblages and in some environmental features was observed. The community was dominated in abundance and species richness by rotifers in most of the water bodies. Fish greatly contributed to the differences in community composition, as fishless ponds presented abundant and diverse cladoceran populations. Nutrient and chlorophyll-a concentration, conductivity and macrophyte cover had also a great influence on these as- semblages, especially in micro- and macrozooplankton. The temporal changes observed in some of these vari- ables affect the proportion of invertebrate biomass of the different groups along the study period. All this environmental heterogeneity produces similar responses in the invertebrate groups, in general well adapted to salinity changes or high trophic conditions. Although the heterogeneity and human disturbances can increase regional diversity, they can cause the disappearance of valuable habitats, and finally, the homogeneity in invertebrate assemblages.

Restoration projects in wetlands are becoming increasingly frequent to recover or to create new aquatic ecosystems, after the significant impact and high degradation they have undergone. In the present study, we focused on the changes in the zooplankton community in a permanent peridunal pond where a restoration was carried out in order to increase its surface as a main objective. For this purpose, the community was compared before and after the restoration (15 years before, the year after and between 3 and 6 years later). Significant changes in environmental variables were observed after pond restoration: chlorophyll a concentration decreased and dissolved oxygen increased. Substantial modifications in the aquatic community were also observed, since species richness and diversity increased after restoration: a large number of new species appeared (84%, mainly cladocerans), from external or internal sources. In addition, zooplankton community structure and composition changed from a low specific richness community copepod-dominated in density (mostly nauplii) before restoration, to another one with higher richness and different composition co-dominated in density by rotifers and nauplii, but with greater abundance of cladoceran species. All this suggests an important change in the ecological functioning of the pond, mainly produced by improvement in habitat heterogeneity and water quality after restoration.

In temporary ponds, reestablishment of zooplankton communities depends on recruitment from the egg bank, the arrival of dispersers from within the region, and on successful establishment of newly arrived species following interaction with local abiotic and biotic factors. When the ponds dry up, zooplankton species may survive as dormant eggs, and since not all eggs hatch in the next season, eggs will accumulate in the sediment over time, representing an archive of the pond's historical biodiversity. To study the effect of “restoration age” (the time since a water body was restored), we studied groups of ponds that were restored in different years (1998, 2003 and 2007). The restoration process involved extensive dredging of sediments which were used to bury the ponds in the 1960s. Our expectation was that the oldest ponds would have the richest zooplankton community, as they have been accumulating biodiversity over a longer time period. We took weekly quantitative samples of zooplankton during four consecutive weeks after flooding to compare taxon richness and zooplankton community composition between ponds of different restoration age during an early stage of zooplankton community re-establishment. Taxon richness was high and similar to regional levels in all the ponds under investigation, suggesting restoration success and unlimited dispersal. Although cumulative richness at the end of the period was not significantly different between ponds, we observed temporal changes within the study period and certain age-related trends in relation to differences in zooplankton composition. These results suggest a difference in the succession of zooplankton communities depending on restoration age (which could be due to historical or local factors) and that this effect becomes evident from the beginning of the pond hydroperiod.

Some of the predicted effects of climate warming in Mediterranean climate are the increase of temperature, change of precipitation patterns and the rise in sea levels. This will have major consequences, mainly in coastal aquatic ecosystems, by the increase of salinity and the reduction of the flooding period, affecting the whole aquatic community. To assess on the possible consequences of the global change in the zooplankton community of Mediterranean coastal lakes, we analized the zooplankton diversity in a set of lakes with different salinity and water permanence time. The ponds were classified in four groups: permanent and temporary freshwater ponds, and permanent and temporary brackish ponds. Whereas we did not detect a great effect of hydroperiod on zooplankton community, the increase in salinity produced (through direct and indirect interaction) a rise in rotifer density and a reduction in cladoceran cumulative richness, richness per visit and diversity. All these differences were remarkable in Permanent Brackish lakes, the group which showed the higher dissimilarity with the other groups of lakes. The disappearance of cladocerans in these systems can lead to an increase in the eutrophication and a reduction of diversity.

Diel vertical migration (DVM) of zooplankton is commonly considered an adaptation for feeding in food-rich and warm surface waters at night and avoiding visual predators during the day. However, the critical assessment of migration patterns frequently suggests that: (i) zooplankton may leave deeper waters with rich, deepchlorophyll layers and move into the epilimnion where food resources are lower and/or (ii) the night-time increase in epilimnetic plankton abundance is not matched by a density decrease in deeper strata. To study these discrepancies, we measured DVM of zooplankton in a 1.3-ha Spanish karst lake (Laguna del Tejo) where the phytoplankton in the deep chlorophyll layer had been labelled with the isotopic tracer 15 N. There were only limited changes in the vertical distribution patterns of rotifers and copepods over the diel cycle, but night-time biomass (mg L 21 ) of the cladoceran, Diaphanosoma brachyurum in the water column of the oxic zone increased 168% in the central area of the lake but there was not a parallel reduction in their density in the metalimnion or hypolimnion. Additionally, the isotopic signatures of the zooplankton in the epilimnion stayed constant from day to night, suggesting that there was little vertical migration. The results suggest that horizontal movements rather than vertical migration explain the increasing abundance of zooplankton in the central epilimnion of Laguna del Tejo during the night and that low food resources in this layer provide no incentive for DVM.

At present, a large number of theories exist which explain the process for choosing communication media in organizations. Channel expansion theory combines a large part of the theoretical foundation for these theories, suggesting that the perceived richness of a communication medium varies according to experience based on the knowledge of the organization’s members. Equally, Regulatory Focus Theory also suggests that individuals behave in a different way when their self regulation states are different. This investigation intends to present a set of proposals based on the existing literature about how strategy type /focus (promotion and prevention) affects the perception of the richness of a communication medium, increasing the explanatory capacity of channel expansion theory.

New habitats are an interesting tool to monitor colonization processes in the light of changes in genetic structure and evolutionary potential of populations. Cladocerans are cyclical parthenogens that offer the possibility to track genetic changes during the colonization process due to the alternation of sexual and asexual phases. The locally called “malladas” are shallow and temporary peridunal ponds in Eastern Spain that were silted in the 1960s and have been recently dug to their original basin. We here describe the colonization process in two of these newly restored ponds by the cladoceran Daphnia magna during their first 3 years. This colonization process followed three critical steps: population founding by the initial colonists, arrival of secondary immigrants and consolidation of the population structure. We found a low number of genotype colonists followed by the establishment of secondary immigrants and a slight decrease in gene flow with time. We discuss the importance of dispersal, founder effects, natural selection, inbreeding depression and genetic drift during the colonization process in the light of the most recent literature.

We compared two freshwater mountain ponds during an annual cycle by focusing on Rotifera and Crustacea. These ponds, Laguna de Bezas and Laguna de Rubiales, are located only 4.5 kilometers apart and share a similar altitude (ca. 1200 m.a.s.1) on the Iberian Mountain range, in Teruel (Spain). Bezas is near-permanent and dries out only in severe droughts; Rubiales is temporary, drying out periodically. They also show important differences in other limnological traits. Bezas has transparent water, harbors a fish population, and has a dense macrophyte cover, whereas Rubiales has elevated turbidity and neither fish nor macrophytes during most of the hydroperiod. These differences are probably why they have significantly different aquatic fauna. We found that rotifers were density-dominant in the zooplankton of Bezas, while Rubiales was dominated by microcustaceans. Ostracods were practically absent at Bezas, whereas the ostracod community at Rubiales was rich and variable.

(2009). Changes in zooplankton and macroinvertebrates in shallow lakes of Southeastern Spain. SIL Proceedings, 1922-2010: Vol. 30, No. 5, pp. 745-748.

The hatching of diapausing eggs from sediment samples of ponds and lakes is a fast, easy, and economical technique proven useful for the assessment of diversity and abundance of zooplankton in permanent habitats. Here, we extend and optimize this approach for temporary brackish ponds which may experience great within-year variation in salinity conditions. We studied the species and numbers of rotifers emerging from the sediments of several brackish ponds and saline lakes from Eastern Spain incubated at the full range of salinity conditions observed at the study sites. On average, 82 % of the total observed species in weekly sampling for one year were detected in a single sample of both the sediments and water column. No statistical difference was found between both methods. However, some rotifer species were only observed in the water column samples, but not in sediment hatchlings, and vice versa. We concluded that both methods are not exhaustive by themselves but are complementary. Salinity affected the estimation of both rotifer richness and the density of individuals of each rotifer species that emerged from the incubated sediments. Differences in the density of emerging animals were also found among sites and among combinations of sites and salinities. The latter result indicates that in order to obtain an estimate of the emergence rate for each rotifer species present at a site, it is necessary to incubate sediments at salinity conditions close to their local values.

Zooplankton assemblages in neighboring ponds can show important spatial and temporal heterogeneity. Disentangling the influence of regional versus local factors, and of deterministic versus stochastic processes has been recently highlighted in the context of the metacommunity theory. In this study, we determined patterns of temporal and spatial variation in zooplankton diversity along one hydrological year in restored ponds of different hydroperiod and age. The following hypotheses regarding the assembling of species over time were tested: i) dispersal is not limited in our study system due to its small area and high exposure to dispersal vectors; ii) community dissimilarity among ponds increases with restoration age due to an increase in environmental heterogeneity and stronger niche-based assemblages;and iii) similarity increases with decreasing hydroperiod because hydroperiod is a strong selective force filtering out organisms with long life cycles. Our results confirmed dispersal as a homogenizing force and local factors as gaining importance with time of restoration. However, short hydroperiod ponds were highly dissimilar, maybe due to the environmental differences among these ponds, or to high stochasticity followed by priority effects under a weak selection pressure. By adding a temporal dimension to the study of zooplankton structuring, we could identify the first months after flooding as being crucial for species richness, especially in short hydroperiod ponds; and we detected differences in seasonal species richness related to hydroperiod and pond age.

Objecte: Cada vegada mes, les organitzacions estan mes conscienciades que l’exit empresarial s’aconsegueix amb el treball constant i energic de tots els seus integrants. Aspectes com el compromis i la motivacio son cabdals. Aquest article, fa referencia a la necessitat cada vegada mes creixent d’utilitzar els canals de comunicacio en linia per gestionar mes eficacment les relacions amb els empleats. Disseny/metodologia: Prenent com a base la teoria de la riquesa dels mitjans de comunicacio, es fa una proposta per a examinarels factors que afecten en una comunicacio eficac, relacionant les senyals d’informacio, la personalitzacio, i la velocitat en dues situacions diferents. Aportacions i resultats: Aquest treball ofereix vuit propostes per tal d’estimular la investigacio futura en els canals emergents. Limitacions: En l’estudi nomes es consideren dos canals de comunicacio basats en internet: correu electronic i missatgeria instantania. Implicacions practiques: Coneixer la percepcio dels treballadors es fonamental per tal de millorar els processos comunicatius en organitzacions i institucions. Els resultats d’aquest recerca poden oferir una visio clara dels efectes de l’us eficient de nous canals de comunicacio. Implicacions socials: La capacitat dels nous dispositius mobils amb connexio permanent online ha afavorit l’us massiu de nous canals de comunicacio. Coneixer els factors determinats que influeixen en la percepcio dels usuaris sobre els nous canals, es un factor determinat en l’eleccio dels mitjans de comunicacio. Valor afegit: Tot i que es manifest l’us intensiu dels nous canals de comunicacio, son pocs els estudis que analitzin els efectes i repercussions del seu us en organitzacions i institucions.

An in vitro nutrient addition bioassay was performed to test the relative inorganic nitrogen (N) and phosphorus (P) limitation of phytoplankton in a Spanish karst lake (El Tejo) during the last part of the stratification period, when nutrient limitation is most pronounced. Nutrient deficiency was tested in samples from three different layers of the lake: the epilimnion, metalimnion and oxic hypolimnion. Nitrogen additions, either without or combined with P, increased phytoplankton growth in all three strata, compared with controls or P treatments. This showed that N was the nutrient limiting phytoplankton growth in late summer-early fall. Since both hypolimnetic diffusion and groundwater fluxes of N-rich waters into the lake are much reduced during summer, N becomes the limiting nutrient as stratification advances. We suggest that in this Mediterranean area with low atmospheric deposition of anthropogenic N and in lakes relatively free of surface run-off, nutrient supply by atmospheric deposition might be a key factor in controlling nutrient deficiency for phytoplankton growth.

The seasonal features of the water chemistry in the saline shallow lakes Laguna de Manjavacas and Laguna del Pueblo (Castilla – La Mancha, Central Spain) were studied during 1990–1991 and in 1997. These lakes were both affected by sewage inputs driving them to a high trophic status. However, whereas sewage inputs entered Laguna del Pueblo directly, wastewater reached Laguna de Manjavacas after running for 8 km through a small riverbed, where natural processes caused partial mineralisation of organic matter. Moreover, water quality was further improved before entering the main water body of Laguna de Manjavacas, since water crossed through a wetland and high amounts of organic matter and inorganic nutrients were retained there. Anyway, in both lakes spatial heterogeneity was mainly associated with the distance to sewage inputs, and this was also reflected by the sediment chemistry. The patterns of water evaporation and precipitation-dissolution of salts strongly determined the salinity of their waters. During the warmest period (which coincided with the main drought period) water losses by evaporation increased water salinity, whereas a higher dilution was found during the cold rainy period. However, the relatively higher amount of low-salinity sewage inputs in Laguna del Pueblo allowed this lake to maintain its hyposaline characteristics. In contrast, Laguna de Manjavacas shifts from hyposaline to hypersaline following the seasonal cycle with different rain and temperature regimes, as the relative importance of the permanent wastewater inputs was lower here than in Laguna del Pueblo. Inorganic nutrient dynamics was determined in both lakes both by the sewage supply and by consumption by phytoplankton, with soluble P depletion following algal blooms.

A large spatial heterogeneity was detected in La Safor, a coastal area with different kinds of small and shallow water bodies. The area exhibits a sharp gradient in eutrophication (0.004–20 mgP l−1; 0.6–457 μg Chl a l−1) and varied water body features (morphology: size, depth; hydrology; vegetation, etc.). These factors result in a high diversity of aquatic habitats within the area. One hundred and twenty eight species of microalgae were identified in the 32 sampling stations studied (in the wet and dry periods). The phytoplankton richness varied between 1 and 21 species, the Shannon-Wiener index range was 0–3 bits, the index of floral originality (IFO) range was 0.1 – 0.6. A total number of 126 species of zooplankton were identified. The zooplankton specific richness ranged from 4 to 26 species, the diversity index and IFO were 0.9–3.7 and 0.1–0.6, respectively. A PCA allowed the ordination of different water body types as a function of total phosphorus, flux of water, water transparency, presence of macrophytes and oxygen. Plankton richness, diversity index, equitability and IFO showed weak relationships to the trophic gradient. The global planktonic biodiversity was higher than expected for such an anthropogenically affected ecosystem. The different, above mentioned conditions contributed to the limitation of biodiversity loss often observed in eutrophic conditions.

Cladoceran assemblages were studied in littoral samples from 44 water bodies in Central Spain, showing great differences in salinity and permanence of water. Principal component analyses (PCA) were performed with data on cladoceran relative abundances to identify the main groups of species. Five main groups of species were found, defining the following types of environments: (I) Small but deep hard water lakes (II) permanent but shallow hard water lakes fed by surface springs, rich in macrophytes (III) ephemeral and shallow soft waters lakes (IV) subsaline and hyposaline lakes in their lower range, specially the permanent ones and (V) saline lakes (salinities>6 mg l−1) subject to short or long periods of dryness. The main species constituting these groups were: Group (I): Acroperus neglectus, Alona guttata, Pleuroxus truncatus, Daphnia longispina; group II: Phrixura leei, Latonura rectirostris, Eurycercus lamellatus; Alonella excisa, Daphnia pulicaria; group III: Ephemeroporus phintonicus, Macrothrix rosea, Moina micrura; group IV: Alona rectangula, Ceriodaphnia reticulata, Tetrocephala ambigua, Diaphanosoma mongolianum; group V: Alona salina, Pleuroxus letourneuxi, Dunhevedia crassa, Moina brachiata, Daphnia magna and Daphnia mediterranea. Sample scores from PCA extracted from the correlation matrix of cladoceran proportions were correlated with limnological measurements. Significant correlations with salinity, alkalinity anions and cations indicate that salinity is an important factor in the distribution of the species. However, species assemblages also reflect other factors, such as temporality and littoral development.

Grazing rates of zooplankton were analysed in the summer of 1999 in Yellow Belly Lake, an oligotrophic system in the Sawtooth Mountains of Idaho (U.S.A.). The colonial rotifer Conochilus unicornis was a dominant species in the epilimnion, with densities reaching 20 colonies 1−1 (ca. 400 ind. 1−1). Clearance rates were measured with an in situ Haney Grazing chamber and synthetic microspheres 5, 9 and 23/μm in diameter. At epilimnetic temperatures of around 14 °C, mean clearance rates for 5µm particles ranged from 30 to 65 µ1 ind.−1 h −1. Clearance rates were 2–9 times higher on the 5µm spheres than on the 9 µm spheres, and C. unicornis almost never fed on the 23 µm spheres. Grazing rates did not change over the diel cycle. Clearance rates declined more than 10-fold as temperatures declined from 14 °C in the epilimnion to 7 °C in the metalimnion. In the epilimnion, grazing by C. unicornis was more important than grazing by crustaceans in the community, at least on particles ≤9µm. The results show the importance of grazing by rotifers in lakes, and the significance of spatial variations that influence grazing rates.

Zooplankton structure and dynamics were studied in a freshwater wetland subject to strong hydrologic fluctuations. This wetland underwent a six-year drought that terminated at the end of 1996. At that time, inundation area and water level increased, diminishing macrophyte cover in some cases and enhancing a continuing eutrophication problem. Sampling was performed monthly from January 1996 to December 1998 in five shallow water sites. Zooplankton were a mixture of limnetic and littoral species (66 rotifer, 15 cladoceran, and 10 copepod taxa, plus unidentified oligotrichid and peritrichid ciliates), the composition of which changed coincident with the shift of the hydrologic conditions. The most common taxa were bdelloid rotifers and Lecane closterocerca. The microcrustancean Ceriodaphnia dubia, Daphnia curvirostris, and Acanthocyclops robustus were frequent. Ciliates were the most important component of zooplankton in terms of biomass, except in spring when cladocerans were dominant. Rotifer biomass was the lowest fraction of zooplankton. When community structure was described by taxonomic classes, mean biomass, or time biomass trajectories, only weak spatial patterns were found following the flux of water in the wetland. Each zooplankton group was distinctly affected by flood. Ciliates and rotifers increased biomass after the flooding, possibly as a result of the enhancement of eutrophication; cladoceran populations decreased after the flooding likely due to macrophyte loss that facilitated planktivorous fish control. Copepods increased biomass consequent to the stabilized water level. There was a clear seasonal trend of zooplankton biomass seemingly unaffected by flood. Ciliates and rotifers had fluctuating low biomass in winter-spring, with maximum biomass in summer-autumn; cladocerans appeared and peaked only in spring; copepods peaked in late winter and spring.

The study of diel vertical movements of zooplankton in a small meromictic karstic lake (lake La Cruz), presenting highly stratified waters, was performed using two different methodologies: (i) samples were taken along the vertical profile and were compared at different hours in a diel cycle; (ii) some plankton traps were located at different depths, covering different periods of time, to catch organisms going upwards and downwards. The main subject of this study has been the vertical movements affecting rotifers since they were dominant in the zooplankton of this lake, but we have also included the results obtained for other zooplankton groups. The results indicate an almost general movement in epilimnetic waters corresponding to the 'normal' pattern of migration (ascent at dusk and descent at dawn); in metalimnetic and hypolimnetic waters, vertical movements were greatly reduced and were more independent of the diel cycle. The results also confirm that the dense populations at these levels of the oxic-anoxic boundary are made up of active animals. Among the causes accounting for our results, the cycles of activity (mainly feeding) connected with the diel cycle could be important in explaining vertical movements of filter-feeder rotifers. In larger zooplankters, visual predation might be the main reason for such behavior.

The zooplankton communities from several lakes and pools in three zones of a karstic area in central Spain were studied in spring and early autumn, in relation to morphometric, physical and chemical characteristics of the lakes. Zooplankton diversity was higher in autumn than in spring and it was positively correlated with lake size (area and depth) in spring, but not in early autumn. This effect is partially explained by the sharp zooplankton stratification in deep lakes, in early autumn. Some morphometric characteristics of lake basins were also correlated with the structure of zooplank- ton communities. Principal component analyses (PCA) and Two-Way Indicator Species Analysis (TWINSPAN) performed on zooplankton data and a posterior correlation analysis with the extracted factors and main limnological parameters showed that trophic state in the first place, and mineral- ization in the second place, were the main sources of variance to explain our data. However, the results of these analyses also show that important sources explaining the variance of zooplankton data include some factors not quantified in the standard limnological analysis, but evidently related to lake typology, such as shallowness and type of water feeding and flux.

Severe nonexertional (resting) chest pain may bedue to myocardial ischemia, esophageal dysfunction,psychiatric disorder, or any combination thereof andfrequently poses a difficult diagnostic challenge. Our aim was to investigate causes of chest painin patients with coronary artery disease. Forty-fivepatients with angiographically proven obstructivecoronary lesions and recurrent chest pain at rest were studied; 18 had refractory pain despite cardiactherapy (problem group), and 27 had documentedmyocardial ischemia (control group). Esophagealmanometry, edrophonium provocation, 24-hr pH studies,and psychiatric interview were performed in all patients. Theclinical evolution and the outcome of specific treatmentduring follow-up was used to establish the etiology ofchest pain. Esophageal dysfunction was identified in all problem patients and in 52% of controls,and the esophagus was incriminated as the source of painin 8 (44%) and 5 (18.5%), respectively. After a meanfollow-up of 49 months (range 24-76 months), the cause of chest pain in the problem groupwas identified as panic disorder in 9 patients (50%),gastroesophageal reflux in 6 (33%), esophagealdysmotility in 2 (11%), and gallstone disease in 1 (6%). Of the control patients, 18 (67%) had ischemicpain alone, while 9 had concurrent causes: panicdisorder in 5 (19%) and esophageal dysfunction in 4(15%). Esophageal dysfunction and psychiatricdisturbances are common in patients with coronary arterydisease presenting with resting chest pain, and maycontribute to patients' symptoms.

There are a large number of theories that explain the process of choosing a communication medium in organizations. The theory of the expansion channels suggests that the perceived richness of a communication medium is contingent upon the knowledge-based experiences of organization members. Likewise, the regulatory focus theory also suggests that individuals behave differently when experiencing different self-regulated states. This research aims to analyze how the kind of self-regulatory strategy (promotion and prevention) and the dimensions of social influence affect the perceived richness of a communication medium.

The main source of variation of rotifer species distributions in lake Arcas-2, a small karstic lake near Cuenca (Spain), was explored by means of principal components factor (PCA) and canonical correlation (CCA) analyses. PCA was performed using rotifer densities and CCA using rotifer densities plus physical and chemical parameters. Factor 1 of PCA separated summer species from winter-spring species and Factor 2 accounted for the variation in the vertical profile. Three summer species with different food habits (Polyarthra dolichoptera, Hexarthra mira and Asplanchna girodi) were grouped together at the positive end of Factor 1, while Factor 2 separated the two hypolimnetic species (Filinia hofmanni and Anuraeopsis fissa) from the rest. The relative position of rotifer species in the space determined by the CCA was roughly the same. The most significant environmental factors that became paired with rotifer distribution in the CCA were temperature and oxygen, and parameters related to water inflow. Segregation of filter-feeding species in the spatio-temporal subenvironments is clearly shown by the multivariate analysis.

‘Oxiclinal’ rotifer species show high concentrations just above the oxic-anoxic interface in the hypolimnion of some lakes. The stratification of their populations is best shown by sampling at close depth intervals and quantifying their densities by the Utermohl technique. With this technique we were able to count males which otherwise pass through filters and more accurately count egg production. We evaluated female, male and egg numbers of the two main oxiclinal species of lake Arcas-2: Filinia hofmanni and Anuraeopsis fissa, during two annual cycles (1990–91). F. hofmanni was an exclusive oxiclinal species. It had an exponential growth phase at the onset of stratification giving a distinct spring peak. The population then maintained a high density during summer, but was almost absent the rest of the year. This cycle is repeated annually but population density can vary among years, depending on winter-spring circulation. Sexuality was always observed when the animal was present in the samples, with a maximum of males and resting eggs at the peak of the population. Resting eggs were always inside females. The annual cycle of A. fissa is displaced with respect to that of F. hofmanni: A. fissa attained greatest densities during summer, until the autumn overturn. Mixis in A. fissa was restricted to the end of the stratification period. Moreover, A. fissa occured throughout the vertical profile and secondarily occupied the oxicline.