Short-term versus long-term changes in the benthic communities of a small coastal lagoon: implications for ecological status assessment

The characteristic high variability and low predictability of coastal lagoons, due to strong changes in marine and freshwater inputs, make these ecosystems an interesting casestudy. The small Melides landlocked coastal lagoon in SW Portugal is a paradigmatic example, with a biological community highly stressed by these phenomena. Benthic macroinvertebrate samples were collected in 1998/99 and 2009 and each year, in different seasons and addressing different environmental conditions influenced by the connection to the sea and rainfall regime. Major spatial and temporal patterns in benthic communities were investigated using some invertebrate attributes (e.g. community composition, density, species richness and diversity). A very low taxonomic species richness and diversity was found in the Melides lagoon and only a much reduced number of species occurred along all sampling periods and in both sampling campaigns. Although the colonization events play a crucial role, the persistence of the observed species was mainly associated to abiotic factors, such as salinity, temperature and dissolved oxygen. Despite the potential reduction in anthropogenic pressure, by the construction of a sewage treatment plant and a reduction of urban occupation, the ecological status did not improve and the high level of natural environmental variably in the lagoon seems to be the dominant stressor influencing benthic invertebrate communitie

Projecto Groundscene: biodiversidade de lagoas costeiras e respectivas bacias hidrográficas como ecossistemas dependentes de águas subterrâneas

Na União Europeia a Directiva Quadro da Água requer a avaliação do estado ecológico de todas as águas interiores (dulciaquícolas e de transição) e costeiras, incluindo os ecossistemas aquáticos superficiais cujo estado ecológico poderá estar dependente do estado das águas subterrâneas (AS). O estado ecológico em lagoas costeiras dependentes de AS depende das interacções AS - água doce superficial - água salgada, pelo que a sobre-exploração das AS pode ter impactos significativos na sua biodiversidade. O principal objectivo do projecto GROUNDSCENE é avaliar as respostas ecológicas face a uma redução da recarga das AS e a um aumento da extracção de água, num cenário de alterações climáticas. Este projecto foi desenvolvido nas Lagoas de Melides e de Santo André (Sudoeste de Portugal), escolhidas como casos de estudo porque ambas recebem AS do sistema aquífero de Sines. Recebem ainda água salgada durante um período curto de abertura ao mar. Este projecto integrou dados históricos de descritores biológicos (macroinvertebrados e peixes) e físico-químicos, referentes às últimas quatro décadas, que foram comparados com os dados recolhidos na actualidade recorrendo às técnicas mais adequadas para cada tipo de habitat. A recolha de dados privilegiou os ecótonos AS-ribeira-lagoa, uma vez que é expectável que estas zonas de interface sejam indicadoras da interdependência entre os compartimentos. Procurou-se igualmente quantificar os volumes das transferências subterrâneas do sistema aquífero para a rede hidrográfica e ecossistemas associados. Foram ainda efectuadas medidas de um conjunto de parâmetros indicadores das condições ambientais. De uma forma geral, os resultados obtidos evidenciaram uma maior diversidade taxonómica nos sistemas ribeirinhos afluentes à lagoa de Melides do que à sua homóloga de Santo André e, em contraste, maior diversidade das comunidades piscícola e de macroinvertebrados bentónicos na lagoa de Santo André, relativamente à de Melides. A análise comparativa dos resultados obtidos e de dados anteriores dos sistemas lagunares demonstram que as comunidades destas Lagoas têm uma elevada variabilidade espacial e temporal, maioritariamente condicionada pelos regimes da sua abertura ao mar e de precipitação. As comunidades das ribeiras são maioritariamente condicionadas pelo respectivo carácter permanente ou temporário e pela diversidade de habitats presentes, com destaque para a heterogeneidade de substrato

Edaphic and arboricolous oribatid mites (Acari; Oribatida) in tropical environments: changes in the distribution of higher level taxonomic groups in the communities of species

We analysed the community of oribatid mites in 25 environments of northern Brazil and one in a rain forest in Peru, encompassing fauna sampled on natural and artificial (nylon-mesh bags) substrata, from primary and secondary forests, caatinga, savannahs, flooded forests, bark and epiphytes of trees, and polyculture. A hundred and forty six species are definitively identified from a total of 444 taxa. To determine changes in the community, we took as a basis of comparison the species dominance of Lower Oribatida vs. Oppioidea and Lower Oribatida vs. Poronota. Even considering the different periods in which the inventories were realized and the different sampling methodology compared, the partition of the species of Oribatid mite in larger groups shows tendencies indicating partition of species dominance among the environments studied, showing that they differed in their suitability as habitats for the Oribatid mite community, mainly in respect to the Lower Oribatida, Oppioidea and Poronota composition. These tendencies should be explored in more detail as more becomes known about the species composition in each environment

Comparative assessment of climate change and its impacts on three coastal aquifers in the Mediterranean

A comparative study on climate change and its impacts on coastal aquifers is performed for three Mediterranean areas. Common climate scenarios are developed for these areas using the ENSEMBLES projections that consider the A1b scenario. Temperature and precipitation data of three climate models are bias corrected with two different methods for a historic reference period, after which scenarios are created for 2020–2050 and 2069–2099 and used to calculate aquifer recharge for these periods based on two soil water budget methods. These multiple combinations of models and methods allow incorporating a level of uncertainty into the results. Groundwater flow models are developed for the three sites and then used to integrate future scenarios for three different parameters: (1) recharge, (2) crop water demand, and (3) sea level rise. Short-term predictions are marked by large ranges of predicted changes in recharge, only showing a consistent decrease at the Spanish site (mean 23 %), particularly due to a reduction in autumn rainfall. The latter is also expected to occur at the Portuguese site, resulting in a longer dry period. More frequent droughts are predicted at the Portuguese and Moroccan sites, but cannot be proven for the Spanish site. Toward the end of the century, results indicate a significant decrease (mean [25 %) in recharge in all areas, though most pronounced at the Portuguese site in absolute terms (mean 134 mm/year) and the Moroccan site in relative terms (mean 47 %). The models further predict a steady increase in crop water demand, causing 15–20 % additional evapotranspiration until 2100. Scenario modeling of groundwater flow shows its response to the predicted decreases in recharge and increases in pumping rates, with strongly reduced outflow into the coastal wetlands, whereas changes due to sea level rise are negligible