The effect of eutrophication abatement on the bivalve Scrobicularia plana

Over the last few decades, the excessive growth of macroalgae and decline of seagrass beds, associated with increased eutrophication, has become a worldwide problem. It is known that submersed aquatic vegetation (SAV) offers stable habitats, allowing the continuous availability of food and protection against predators and contributing to biodiversity, sediment stability and water transparency when compared to areas covered by macroalgae mats. In the Mondego estuary (Portugal), several mitigation measures (nutrient-load reduction, seagrass-bed protection and freshwater-circulation enhancement) were implemented in 1998 in order to promote the recovery of the seagrass beds and the entire surrounding environment following a long period of eutrophication. Here the success of this restoration project is evaluated by comparing the water nutrient concentrations, the extent of seagrass cover and the dynamics of the bivalve Scrobicularia plana before and after the implementation of the management measures. During the period in which environmental quality declined, S. plana's adult abundance, total biomass and growth production also declined, parallel with the almost total disappearance of Zostera noltii. After the implementation of management measures, dissolved nutrients and green macroalgal blooms were much reduced, and seagrass beds started to recover. The S. plana population also responded positively, becoming more structured (including individuals of all age classes), with higher biomass and growth production.http://www.sciencedirect.com/science/article/B6WDV-4FCRFDM-1/1/d653dc6f4a1a90598f31649f450376a

Salt marsh halophyte services to metal-metalloid remediation: assessment of the processes and underlying mechanisms

Salt marshes are widely distributed and most productive ecosystems in the temperate zones on the globe. These areas perform vital ecological functions and are populated mainly by halophytes—plants that are able to survive and reproduce in environments with exceptionally high salt concentrations. In salt marshes, in addition to tolerating high salt concentrations, salt marsh halophytes have to cope with damages caused by multiple anthropgenic pressures including metal and metalloid pollution. Extensive studies have been performed aiming at exploring naturally occurring endemic salt marsh halophytes with extraordinary potential for metals and metalloids remediation. However, a knowledge gap is perceptible on the basics of salt marsh halophyte adaptation/ tolerance to the joint action of damaging factors such as high concentration of salt and presence of metals–metalloids. In light of available literature, the current paper is critical in: (i) highlighting ecological significance of salt marsh halophytes and their use as bioindicators or biomonitors of metal–metalloid pollution; (ii) analyzing salt marsh halophyte significant contributions for metal- and metalloid-remediation processes; (iii) overviewing salt marsh halophytes–microbes interaction influence on metalphytoremediation processes; and (iv) cross-talking important physiological/ biochemical strategies adopted by salt marsh halophytes for salinity-, metal-, and metalloid-tolerance. Conclusively, the paper highlights important aspects so far less explored in the context of salt marsh halophyte services to metal–metalloid remediation and underlying mechanisms. The discussion will enable researchers and environmentalists to set further exhaustive studies aiming at efficient and sustainable management of rapidly mounting salt marshes metal–metalloid contamination issues