Is Microtox® toxicity related to potentially harmful algae proliferation in Mediterranean salt marshes?

Is Microtox® toxicity related to potentially harmful algae proliferation in Mediterranean salt marshes? Mediterranean salt marshes are ecosystems that are highly influenced by sea changes and freshwater inputs from runoff. In these ecosystems, toxic and nontoxic algae blooms often produce Jarge and unpredictabJe biomasses of phytoplankton. The Microtox@) test has been described as a successful, quick method for detecting toxicity in various phytoplankton taxa. Our study sought to test the efficiency of Microtox® in detecting toxic HAB in Mediterranean salt marshes. The results showed that the Microtox® test was able to detect toxic substances in the particulate matter of several lagoons in the Emporda salt marshes. This Microtox® toxicity coincided with periods when potentially harrnful cyanobacteria, dinoflagellates and haptophytes had a high biomass. The results suggest that potentially harmful phytoplankton cannot be ruled out as a source of Microtox® toxicity or as a source of other organism kills and subacute effects in Mediterranean salt marshes.Las marismas mediterráneas son ecosistemas altamente injluenciados por la entrada de agua marina y de agua dulce, procedente de la escorrentía. En estos ecosistemas, las proliferaciones de algas tóxicas y no tóxicas sin patrón temporal o espacial, alcanzan altas e impredecibles biomasas de fitoplancton. El ensayo Microtox® ha sido descrito como un rápido y eficiente método para detectar la toxicidad de diferentes taxones de fitoplaneton. Nosotros hemos hecho una primera aproximación para determinar la eficiencia del test Microtox® en la detección de proliferaciones algales tóxicas en las marismas mediterráneas. Se ha podido concluir que hay substancias tóxicas, en la materia particulada de diversas lagunas de las marismas del Emporda, que el método Microtox® es capaz de detectar. Esta toxicidad detectada por Microtox® se da en periodos en que cianobacterias, dinojlagelados y haptófitos potencialmente tóxicos presentan alta biomasa. Los resultados sugieren que el fitoplancton potencialmente tóxico no puede ser descartado como causante de la mortalidad o de efectos subagudos a otros organismos de las marismas mediterráneas

Intra and inter-annual variation of functional structure of macroinvertebrate assemblages in Mediterranean temporary ponds

Temporal variation of the functional structure of macroinvertebrate assemblages in Mediterranean temporary ponds has been studied in Sardinia (Italy). Sixteen small and shallow ponds (less than 2 ha and less than 2 m deep) subject to low human pressure were sampled in different periods

Seasonal carbon fluxes from vegetation and soil in a Mediterranean non-tidal salt marsh

Salt marshes are important ecosystems for carbon sequestration. However, while studies of atmospheric carbon exchange fluxes have been broadly performed in tidal salt marshes, they are scarce in non-tidal salt marshes. In this study we measured, throughout one year, instantaneous net CO2 exchange rates from four halophytes (Sarcocornia fruticosa, Halimione portulacoides, Elytrigia atherica and Salicornia patula), which are dominant species of their corresponding habitat (an halophilous scrub, a salt meadow and a glasswort sward) of a Mediterranean non-tidal salt marsh. Soil CO2 and CH4 fluxes from these habitats were also measured. E. atherica, a perennial herbaceous species, showed the highest photosynthetic rates during the entire year, but S. patula, an annual succulent herb, had also remarkable photosynthetic rates in summer. Interestingly, the woody fraction of the two perennial shrubs, S. fruticosa and H. portulacoides, showed CO2 uptake during most of the daily measurements. Regarding the studied habitats, the halophilous scrub and the salt meadow showed higher soil CO2 emissions than the glasswort sward, being these values, in general, higher than those reported for tidal salt marshes. Both soil absorption and emission of CH4 were detected. In particular, CH4 emissions were remarkably high, similar to those found in low-salinity marshes, and, in general, higher than those reported for salt marshes with a high water table salinity. Soil mineralization quotients of the halophilous scrub and the salt meadow were lower than those measured at the glasswort sward, suggesting a higher soil carbon sequestration potential of the first two habitats

Crustacean assemblages of coastal wetlands from fragmented and scarcely isolated islands compared with the mainland

The present study compared crustacean assemblages from coastal wetlands between a fragment archipelago and a landmass. The study included four typical crustacean taxonomic groups (i.e. Cladocera, Copepoda, Ostracoda and Malacostraca) from the Balearic Archipelago region as an example of a fragment island (Archipelago') and the Catalonia region as the landmass (Mainland'; Spanish Mediterranean coast). We tested null hypotheses based on the expected similarity between Archipelago and Mainland in terms of crustacean assemblages and biodiversity. Similar relationships of those community attributes with environmental variables were also expected in both regions. The results partially met the null hypotheses. We found that crustacean taxonomic composition varied between Archipelago and Mainland, likely due to peculiar biological and biogeographical processes acting in the Archipelago. The relationship between crustacean assemblages and the environmental variables was mostly similar between Archipelago and Mainland, as expected. Both regions also showed similar patterns of species distribution (i.e. Archipelago and Mainland coastal wetlands were characterised by a few dominant species). This result could be masked by the filter' effect exercised by the harsh conditions of coastal wetlands. Moreover, the total diversity values (gamma biodiversity) in the Archipelago were similar to the values for the Mainland, supporting the hypothesis that fragment islands can be of substantial value for the conservation of global biodiversity.Peer reviewe

COLONIZATION PROCESS IN NEW CREATION MEDITERRANEAN COASTAL LAGOONS

The colonization process in new creation Mediterranean salt marsh lagoons is influenced by hydrological fluctuations characterised by flooding-confinement periods. This pattern has direct effects on water characteristics (such as nutrient concentration), but it also effects the connectivity structure between lagoons impacting main metacommunity dynamics. Unfortunately, these ecosystems have suffered transformations due to urbanization process that has contributed to its degradation. This is the case of La Pletera salt marshes, located in the NE of Catalonia, in where a recovery and restoration European LIFE project (LIFE13 NAT/ES/001001) that included the restoration of existing lagoons and the creation of new ones has been done. In this study, we analysed the structure of aquatic macrofauna community of these new created lagoons just after its creation and five years after its creation with the aim of assessing the colonization assembly process. Our results showed a fast colonization of the species with active dispersion since they dominated the communities right after lagoon creation (Diptera). In contrast, species with passive dispersion (Gastropoda and Amphipoda) that have a lower dispersive capacity were dominant at the last sampling survey, 5 years after creation. This could be explained by flooding periods that connect all wetland waterbodies favouring the arrival of both, active and passive dispersers. Moreover, we observed an increase in the abundance and biomass of taxa with lower dispersion capacity but without affecting the overall community richness values

Is ecosystem size more important than locality in determining the environmental characteristics of temporary ponds?.

Ecosystem size plays a key role in determining ecosystem functioning, affecting community stability and structure at both trophic and taxonomic levels. However, less is known about the influence of ecosystem size on environmental characteristics; for example, do larger ecosystems have higher nutrient availability? The nature of this relationship is important for gaining a better understanding of whether the effects of ecosystem size on community functioning are direct or indirect. Indirect effects may exist when the environmental characteristics of larger ecosystems are different from those of smaller ones, and thus the different functioning of communities observed along the ecosystem-size gradient may respond to, for instance, different levels of nutrient availability, and not uniquely to different ecosystemsizes. Here,we tested whether the environmental characteristics (i.e., the physical, chemical and biological characteristics) of temporary ponds of various sizes differed. We chose temporary ponds because they are abiotic controlled systems in which abiotic factors have a strong influence on aquatic communities. However, temporary ponds are usually spatially clustered; consequently, pond locality might also be important in determining the environmental characteristics of a pond (i.e., ponds close to one anothermay share similar features).We therefore examined whether pond locality is a more important factor than size in determining the environmental characteristics of a pond. To do so, we sampled environmental characteristics (chlorophyll-A, nutrient concentrations, macrophyte biomass, water temperature, conductivity, pH, dissolved oxygen, and total organic and inorganic carbon) of ponds in 5 different localities. A cluster of ponds (10 to 12) was sampled in each locality. Ponds encompassing a wide range of sizes were selected for sampling within each locality. We also performed a meta-Analysis (including data from 27 temporary pond localities) to investigate whether the environmental characteristics of the ponds sampled in this study were representative of Mediterranean temporary ponds, and thus if such characteristics could be used to distinguish between Mediterranean temporary ponds from temporary ponds located outside of the Mediterranean region. Our results showed that locality had a strong effect on the environmental characteristics of temporary ponds, whereas size had only a weak influence; only chlorophyll-A and pond depth showed a robust relationship with size, as both increased with pond size independently of locality. Moreover, our results suggest that the typology of the temporary pond (i.e., if they were mountain temporary ponds, salt marsh ponds or lowland ponds) had a larger influence on several environmental characteristics than did regional location (i.e., Mediterranean). El tamaño de los sistemas juega un papel clave en el funcionamiento de los mismos, afectando la estabilidad de las comunidades y su estructura, tanto a nivel funcional como taxonómico. Sin embargo poco se conoce de la relación del tamaño del sistema sobre las características ambientales. Por ejemplo, ¿tienen los ecosistemas de mayor tamaño una mayor disponibilidad de nutrientes? Esta relación es relevante para entender si el efecto del tamaño es directo o indirecto. Efectos indirectos se dan si ecosistemas de mayor tamaño presentan características ambientales distintas a los de menor tamaño. En ese caso, las diferencias observadas en el funcionamiento de las comunidades a lo largo del gradiente de tamaños podrían responder, por ejemplo, a distinta disponibilidad de nutrientes, y no únicamente a la diferencia de tamaño de los sistemas. En este estudio se analiza si lagunas temporales de distinto tamaño tienen distintas características ambientales. Sin embargo, las lagunas temporales suelen encontrarse agrupadas, compartiendo unas mismas características locales (p.e. la geología, paisaje, la altitud, microclima, etc.), que pueden también afectar a sus características ambientales. De ahí que sea necesario considerar el efecto localidad. Este estudio analiza el efecto del tamaño y el de la localidad, sobre las características ambientales de las lagunas temporales (nutrientes y clorofila-a, biomasa de macrófitos, temperatura del agua, conductividad, pH, oxígeno disuelto, y carbono orgánico e inorgánico total). Para ello, se han considerado 5 sistemas de lagunas temporales. En cada sistema (i.e. localidad) se muestrearon entre 10 y 12 lagunas, seleccionadas para obtener el mayor rango de tamaños posible. Para identificar si las características ambientales de las lagunas estudiadas eran representativas de lagunas temporales mediterráneas y si se podían discriminar de las observadas en lagunas temporales fuera de esta región, se ha realizado un meta-análisis (incluyendo 27 grupos de lagunas temporales). Nuestros resultados indican que la localidad es más determinante que el tamaño por lo que a características ambientales se refiere. Sólo la clorofila-a y la profundidad se relacionaron con el tamaño de manera robusta (mostrando la misma relación independientemente de la localidad). Además, algunas de las características ambientales de las lagunas temporales se ven más influenciadas por la tipología de laguna (es decir, si se encuentran en zonas montañosas, de marisma, o en tierras bajas) que por el hecho de que la laguna se encuentre dentro de la región mediterránea

ECOLOGICAL RESTORATION PROMOTES ZOOPLANKTON NETWORK COMPLEXITY IN MEDITERRANEAN COASTAL LAGOONS

Ecological recovery following restoration is typically evaluated using metrics based on species diversity and composition. However, increasing evidence suggests the success of long-term ecological recovery is better evaluated when more complex attributes such as biotic interaction networks are targeted. For example, at the beginning the influence of nearby habitats can promote colonization leading to similar communities in restored or newly created lagoons, but communities often diverge from surrounding water bodies at later successional stages. These changes have been attributed to the effect of biotic interactions, but few studies have tested this assumption. Here, we analyse the zooplankton community of a Mediterranean coastal wetland subjected to a restoration process that involved the creation of new lagoons. We analysed community dissimilarity patterns and used mixed graphical models to infer interaction networks from abundance data. Increasing differences in the community structure between new and old lagoons were detected from the second year after their creation. The overall interaction network was more complex in new than in old lagoons. Interestingly, the network structure in old lagoons increased its complexity three years after restoration. We show how the inclusion of interaction networks for the monitoring of ecosystem recovery reflects unique facets of community complexity, otherwise overlooked when targeting diversity metrics alone

Heterogeneity in the isolation of patches may be essential for the action of metacommunity mechanisms

The spatial isolation gradient of communities and the gradient in the species dispersal ability are recognized as determinants of biodiversity in metacommunities. In spite of this, mean field models, spatially explicit models, and experiments were mainly focused on idealized spatial arrangements of communities leaving aside the combining role of dispersal and isolation gradients in metacommunity processes. Consequently, we have an incipient understanding of the role of the real spatial arrangement of communities on biodiversity patterns. We focus on six metacommunities for which confident information about the spatial arrangement of water bodies is available. Using coalescent metacommunity models and null models that randomize the location of water bodies, we estimated the potential eect of the landscape on biodiversity and its dependence on species dispersal ability. At extremely lowor high dispersal abilities, the location of ponds does not influence diversity because dierent communities are equally aected by the low or high incoming dispersal. At intermediate dispersal abilities, peripheral communities present a much lower richness and higher beta diversity than central communities.Moreover,metacommunities from real landscapes host more biodiversity than randomized landscapes, a result that is determined by the heterogeneity in the geographic isolation of communities. In a dispersal gradient, mass eects systematically increase the local richness and decrease beta diversity. However, the spatial arrangement of patches only has a large importance in metacommunity processes at intermediate dispersal abilities, which ensures access to central locations but limits dispersal in isolated communities. The ongoing reduction in spatial extent and simplification of the landscape may consequently undermine the metacommunity processes that support biodiversity, something that should be explicitly considered in preserving and restoring strategies

Crustacean and aquatic insect assemblages in the Mediterranean coastal ecosystems of Empord'a wetlands (NE Iberian peninsula)

Coastal wetlands are characterized by high biodiversity, which is one of the main criteria considered when establishing protection policies or when proposing adequate management actions. In this study, the crustacean and aquatic insect composition of the Empordà wetlands is described. These two faunal groups contribute highly to the total biodiversity in these wetlands but are seldom considered when managing natural areas. A selection (84 sampling points) of all water body types present in the Empord'a wetlands were sampled monthly (surber and dip net with a 250 μm mesh). Sampling was carried out during 3 surveys (1991-92, 1996-97 and 1999-2000). A rich fauna of 125 crustacean and 295 aquatic insect taxa was identified. We characterized each water body type using the most abundant species and the relative species richness of the taxonomic groups. A classification of the water body types, according to similarity between inventories, groups the brackish and hyperhaline systems in one cluster and the various freshwater systems in another one. Among freshwater systems, lotic waters and freshwater wetlands have a high similarity, whereas rice fields and freshwater springs have a low similarity.Los humedales costeros se caracterizan por una alta biodiversidad, que es uno de los principales criterios considerados al establecer políticas de protección o al proponer acciones de gestión adecuada. En este estudio se describe la composición de crustáceos e insectos acuáticos de los aiguamolls del Empordà. Estos dos grupos faunísticos contribuyen de forma importante al total de la biodiversidad en los humedales, pero raramente se tienen en consideración al gestionar las áreas naturales. Se muestreó mensualmente una selección (84 puntos de muestreo) de todas las tipologías de masas de agua presentes en los aiguamolls de l'Empordà mediante redes surber y salabres de poro de malla de 250 μm. El muestreo se llevó a cabo durante atres campañas (1991-92, 1996-97 y 1999-2000). Se identificó una riqueza faunística de 125 taxones de crustáceos y 295 taxones de insectos acuáticos. Cada tipología de masa de agua se caracterizó utilizando las especies más abundantes y la riqueza específica de los grupos faunísticos. La clasificación de las tipologías de masas de agua, según la similaridad entre inventarios faunísticos, agrupó los sistemas salobres y hiperhalinos en un grupo. Entre los sistemas de agua dulce, los sistemas lóticos y los humedales de agua dulce presentaron una alta similaridad, mientras que los arrozales y las surgencias de agua dulce mostraron una baja similaridad