Trace metal contents in the mussel Mytilus galloprovincialis from Atlantic coastal areas in northwestern Morocco: Levels of contamination and assessment of potential risks to human health.

The bioaccumulation of trace metals Cd, Cr, Cu and Zn in soft tissues of the mussel Mytilus galloprovincialis was studied seasonally along the Atlantic coast of northwestern Morocco. Average concentrations (µg g-1 dry weight) decreased in the following order: Zn (141.61 ± 78.06) > Cr (22.57 ± 15.47) > Cu (18.95 ± 20.01) > Cd (16.33 ± 19.01), with higher amounts during wet seasons. The "Metal Pollution Index" and "Individual Multimetal Bioaccumulation Index" suggested a higher mussel contamination in industrialized areas. Moreover, Cd and Cr concentrations were above the permissible guidelines' limits. The related risks to human health associated with mussel consumption were also assessed. The "Target Hazard Quotient" for Cd and Cr revealed a threat to children when mussels originated from polluted stations, while the "Hazard Index" indicated a hazard to them in all stations. Regarding the "Maximum Safe Consumption", children should not consume mussels, even in low quantities. This study represents the first datum in Morocco to assess such a risk to human health.

First assessment of phytoplankton diversity in a Marrocan shallow reservoir (Sidi Abderrahmane).

In order to find effective measures to control a Moroccan shallow reservoir (Sidi Abderrahmane), a better understanding of phytoplankton composition, abundance, spatial and temporal distribution it is necessary. Trophic level and the stability status were assessed upon the basis of Shannon diversity index (H'), species richness (S), and evenness (J) index. Statistical tests were used to evaluate the different relationships between phytoplankton and the concentrations of several physico-chemical parameters, and the main soluble nutrients. In surveys, the samples were taken fortnightly from May 2011 to December 2012. 64 taxa belonging to seven groups of phytoplankton were identified, including Bacillariophyceae (25 taxa), Chlorophyceae (22 taxa), and Cyanophyceae (9 taxa). Aulacoseira granulata, Nitzschia palea, Scenedesmus acuminatus, and Oscillatoria sp, were the main contributors to the dissimilarity in temporal distribution. Phytoplankton population never reached a monospecificity situation. Shannon and evenness indices were between (0.0001 < H' < 0.15; 0.003 < J < 0.085) and manifested a young phytoplankton community with high multiplying power. There were significant correlations between total phytoplankton (r = 0.015, p < .01) and water temperature. Significant negative correlations were observed between transparency and Cyanophyceae (r = -0.208, p < .05) and between the number of species and transparency (r = -0.206, p < .05), orthophosphorus (r = -0.377, p < .01), and nitrates (r = -0.301, p < .01). A negative correlation was found between Orthophosphorus and Chlorophyceae (r = -0.377, p < .01). Similar correlations were also observed with nitrates and Chlorophyceae (r = -0.297, p < .01), Silica and Bacillariophyceae (r = 0, p < .01) and total phytoplankton (r = -0.372, p < .07). The underwater light condition, as indicated by Secchi depth fluctuations, hydraulic process conditions (short residence time, short outflow/inflow ratio) were shown to be the limiting factors in regulating the density of phytoplankton. With reference to Palmer pollution index, test results indicated an oligotrophic or mesotrophic reservoir. The data presented provide the first contemporary account of the level of algal diversity present, the prominent environmental conditions and trophic status of Sidi Abderrahmane reservoir waters.

[Copepods distribution in relation to a Cape Ghir upwelling filament (Moroccan Atlantic coast)]. / Distribution des copépodes en relation avec la dynamique du filament de Cap Ghir, (Côte atlantique du Maroc).

The study of the Cape Ghir upwelling filament (31°N) focalizes to describe the dispersive mechanism, caused by the upwelling. The zooplankton was sampled during five oceanographic cruises conducted between 2008 and 2009. Surface temperature and chlorophyll "a" were also measured along with sampling. The distribution of environmental parameters accused extensions that show the path of the filament. Copepods constitute the largest fraction of zooplankton community and represented by 86 species, majorly dominated by Acartia clausi and Oncaea venusta. A number of species of deep or cold waters have been recorded in the area corresponding to a net resurgence of cold water. The analysis of the copepods distribution allowed to view the path of the filament at different times of the year. The distribution of the species A. clausi, neritic specie was observed in the open ocean, shows a result of this dynamic.

Enhanced open ocean storage of CO2 from shelf sea pumping.

Seasonal field observations show that the North Sea, a Northern European shelf sea, is highly efficient in pumping carbon dioxide from the atmosphere to the North Atlantic Ocean. The bottom topography-controlled stratification separates production and respiration processes in the North Sea, causing a carbon dioxide increase in the subsurface layer that is ultimately exported to the North Atlantic Ocean. Globally extrapolated, the net uptake of carbon dioxide by coastal and marginal seas is about 20% of the world ocean's uptake of anthropogenic carbon dioxide, thus enhancing substantially the open ocean carbon dioxide storage.