No abstract

Seagrass meadows are productive ecosystems that contribute to climate change mitigation by accumulating 'Blue Carbon' in their plant biomass and sediments. However, there is wide variation in reported sediment carbon stocks (Cstocks) across different global regions and between meadows composed by different seagrass species. Therefore, understanding the drivers for sediment carbon stocks (Cstocks) variation is crucial to developing effective conservation and restoration projects for seagrass ecosystems. This study compares and analyses the influence of a range of environmental variables on the variation in sediment Cstocks for six intertidal seagrass meadows within the Solent, in southern England. There were significant differences between sites for all variables except leaf density, and concentrations of the sediment pore water nutrients, nitrites and sulphates. Sediment dry bulk density, mean grain size, sorting coefficient, % mud, elevation above sea level, and pore water salinity showed the highest levels of association with Cstocks when assessed individually. Multivariate analyses showed that sediment dry bulk density, sorting coefficient, % mud, and pore water pH and concentration of nutrients showed the greatest influence on Cstocks. Moreover, sediment characteristics such as dry bulk density, sorting coefficient and % mud, acted in 2 conjunction to explain the bulk of the variation in Cstocks among sites. Therefore, sediment characteristics should be considered as important indicators for carbon storage potential in intertidal temperate seagrass meadows used for climate change mitigation.

This study determined the concentrations of eleven metals in the blue crab, Callinectes danae, from nine sites in the Santos Estuarine System of Sao Paulo State, Brazil. The results were compared to guidelines established in the United States, Europe and Brazil for the safety of human consumers. Muscles of blue crabs were removed by dissection and concentrations of Al, Cd, Co, Cr, Cu, Fe, Hg, Mn Ni, Pb and Zn were determined. In general, the concentrations of metals were low, and the crabs were regarded as safe for human consumption. Crabs from a single site (site 4) exceeded the guidelines established by the United States and Europe, but not Brazil, for Pb, with a mean tissue concentration of 1.725 μg g(-1). With the exception of Al, Fe and Ni, significant differences were noted between sites in the concentrations of each metal in crab tissue.

The present study evaluated the effectiveness of Amazonian nut (Bertholletia excelsa) as an alternative source of vegetal protein in tambaqui (Colossom a m acropomum)diet. Performance and physiological status of fish fed for 60 days were evaluated. Four experimental isonitrogenous diets with 36% crude protein were formulated with increasing levels of nut meal (0, 10, 20 and 30%)