Caracterização geoquímica dos sedimentos em um ambiente hipersalino artificial

A geoquímica dos sais e nutrientes encontrados em salinas solares está associada às características hidrodinâmicas e biológicas destes ecossistemas,encontrados nas zonas tropicais e subtropicais em todo o mundo. Esta pesquisa foi desenvolvida na Salina Miramar, localizada na cidade de Areia Branca no litoral setentrional do estado do Rio Grande do Norte, com o objetivo de realizar a caracterização geoquímica e textural em amostras de sedimentos coletadas em 03 evaporadores com salinidades distintas (40, 70, 120 g.L-1). Foi realizada uma análise estatística multivariada nos resultados obtidos em relação aos teores de matéria orgânica, pH,granulometria, cálcio, carbono, nitrogênio e fósforo total.Foram identificadas variações em relação ao padrão de acumulação de nutrientes nos sedimentos, sendo possível distinguir 03 setores com características distintas na salina, em função da salinidade. Dentro dos diferentes perfis analisados, verificou-se que as maiores concentrações de nutrientes foram identificados nos sedimentos de superfície (5 - 10 cm) a 70 g.L-1. Com base nos resultados obtidos, conclui-se que as salinas representam zonas de retenção de nutrientes, impedindo que parte destes, venha de fato a contribuir com o processo de eutrofização da zona costeira

Composition and seasonal variation of epigeic arthropods in field margins of NW Portugal

Field margins act as shelters for different arthropod taxa in agricultural fields. Several factors may promote seasonal changes in arthropod communities, especially in regions with marked seasonality, such as Mediterranean areas. Epigeic arthropods were sampled from the margins of fields located in northwestern Portugal during 2 contrasting seasons, spring and autumn. Organisms were identified to family or order level and seasonal variation in arthropod communities was evaluated. Abundance, group richness, and feeding guild parameters were affected by sampling season, with both abundance and richness being higher in spring. Of the groups captured in both seasons, most evidenced either higher abundance in spring or similar abundance between seasons. Ants constituted one of the most abundant trophic guilds in spring but one of the least captured in autumn, while catches of parasitoids and parasites were not affected by sampling season. Results indicate that the higher taxa approach is useful to distinguish seasonally distinct communities

Biodiversity offsets: from current challenges to harmonized metrics

Biodiversity offsets are compensatory mechanisms increasingly used to address ecological impacts resulting from human activities. We review the scientific literature on biodiversity offsets, published between 1999 and 2014. We found that biodiversity offset studies have increased through time. The majority of studies have been carried out in the USA. The development of biodiversity offsets schemes faces conceptual and practical challenges. The conceptual challenges discussed in the literature are: choice of metric, spatial delivery of offsets, equivalence, additionality, timing, longevity, ratios and reversibility. The practical challenges reported in the literature are: compliance, monitoring, transparency and timing of credits release. Amongst these, choice of metric and location are paramount and are related to the multidimensional nature of biodiversity and the values society places on biodiversity. Harmonized metrics such as the Essential Biodiversity Variables (EBVs) help to address these challenges by providing comparability of biodiversity loss and gain amongst locations