Variabilite Oceanographique De La Zone D’el Jadida – Jorf Lasfar (Maroc)

Une campagne océanographique côtière a été réalisée en Juillet 2018 entre El Jadida et Jorf Lasfar. Cette zone est caractérisée par la présence d'algues rouges et présente une bathymétrie très régulière de la côte à l’isobathe 20m. Les paramètres océanographiques collectés au cours de cette mission montrent que la colonne d'eau est bien stratifiée avec des eaux froides riches en nutriments au fond et relativement plus chaudes et déficientes en nutriments en surface. La zone étudiée est très influencée par la forte concentration des phosphates provenant des rejets de Jorf Lasfar. Durant la période de la campagne, la stratification verticale pourrait s’expliquer par la faible activité des résurgences des eaux froides profondes. Malgré cette stratification, la colonne d'eau était bien saturée en oxygène dissous aussi bien en surface qu’au fond. A coastal oceanographic cruise was carried out on July 2018 between El Jadida and Jorf Lasfar. This area is characterized by the presence of red algae and presents a very regular bathymetry from the coast to isobaths 20m. The collected oceanographic parameters during this cruise show that the water column is well stratified with cold waters rich in nutrients at the bottom and relatively warmer and deficient in nutrients on the surface. The area study is very influenced by the high concentration of phosphates originated from Jorf Lasfar. During this summer’s period, the vertical stratification could be explained by the low activity of the resurgences of cold deep waters. Despite this stratification, the water column is well saturated on dissolved oxygen both on the surface and at the bottom

Structure, diversity and habitat characterization of Copepods from the Cape Ghir upwelling, Morocco

The zooplankton, of the Cape Ghir filament area in Morocco (31°N), was sampled during five oceanographic cruises conducted between 2008 and 2009. Physical and chemical parameters were measured. In total, 11 stations were sampled on two radial perpendiculars: one latitudinal (31°N) with 7 stations coast-large and the other longitudinal (10°09' W) with 5 stations North-South. The intersection between the two radial corresponds to station 4. Copepods constitute the largest fraction of zooplankton community and represented by 86 species. The temporal variability in the copepod community structure showed that the dominant species listed may change their dominance during the study period. Their composition could be analyzed for changes in community structure associated with oceanographic variation with statistical analysis. The relation between the distribution of copepods species and the environment parameters, shows that some species (Paracalanus parvus, Oncaea venusta, Acartia clausi, Oithona nana and Euterpina acutifrons) are mainly correlated with chlorophyll 'a' and nutrients. However, other species (Oithona plumifera, Oithona similis and Clausocalanus arcuicornis) are correlated with temperature and salinity. Eight copepods species “Acartia clausi, Calanus helgolandicus, Neocalanus gracilis, Oithona nana, Oithona similis, Oithona plumifera, Oncaea venusta and Paracalanus parvus” are characterized by their high frequency and their dominance in all periods and were analyzed specially with their relation to the hydrological parameters to determinate their Environmental Preference Habitat. The global quotients were calculated in relationship with each of the hydrological and productive parameters; considered as the most influencing on the distribution of these species. Moreover, the temperature and the chlorophyll 'a' seem to be the most important factors in the determination of the copepod’s habitats in Cape Ghir area

Circulation Marine de la Baie de Cintra (Sud du Maroc) par Modèle Hydrodynamique 2D

The marine circulation of Cintra bay located at Dakhla Oued Eddahab area (south of Morocco 23°08’N-16°20’W) has been studied from October to November 2016 by 2D hydrodynamic model. This study aims to understand the marine circulation of this bay and its hydrodynamic functioning. Mainly governed by wind and semidiurnal M2 tides, currents are generally strong in intensity (mainly > 0.5 m.s-1 ) outside the bay. Inside the bay, their intensity are less than 0.3 m.s-1 and generally oriented to the south of the bay due to the influence of the trade winds (NE). Due sometimes to the influence of W and/or SW winds, the coastal circulation of the bay is oriented from the south to the north, impacting its northern part

Etat Oceanographique De La Lagune De Oualidia, Maroc (2011-2012)

The study of the Oualidia lagoon aims to establish the state of knowledge of the environment of this ecosystem after the construction of an inner dam in 2011 and the ecological functioning of the lagoon. For that, several campaigns were carried out between February 2011 and October 2012 and were the subject of a seasonal monitoring for the collection of the main biotic and abiotic parameters of the environment of this ecosystem. During the construction of the inner dam on 2011, a hydrological variability was marked in summer by low oxygen levels and maximum temperature variation between the two tides. Since the completion of the construction of the inner dam, there has been a significant increase in nutrients, mainly nitrogenous elements, and an increase in turbidity caused by an improvement in hydrodynamics, which has particularly increased of the sandpit modified the morphology and moved on south, creating a new main channel structure in 2011. This hydrodynamic was manifested on the upstream area by a decrease of the sedimentary organic matter due to the trapping of fine sediments in the inner dam. At the immediate level of the upstream area (Slikkes and Schorres), the hydrodynamic is relatively low, which has reduced the sedimentation rate on the upstream of the lagoon. The Oualidia lagoon is situated in a littoral zone influenced by the enrichment in deep cold waters loaded with nutritive salts, which invade it during the high tide, and would be, consequently after construction of the inner dam, protected from any confinement of the ecosystem

Short-term variation of zooplankton community in Cintra Bay (Northwest Africa)

Summary: This is the first study that describes the spatial-temporal distributions of the zooplankton community and potential control factors in Cintra Bay. Zooplankton were sampled using a bongo net, 150 μm mesh size, during two surveys, in autumn 2015 and spring 2016, extending from the coast to the open sea. Fourteen zooplankton groups were identified, where copepods represented 49.1% and 92.5% of the total abundance in autumn 2015 and spring 2016, respectively. Tintinnids accounted for 39.7% and 4.7%, respectively. The total zooplankton abundance was higher in autumn (55 992 ind m−3) than in spring (2123 ind m−3). Nineteen species of copepods, belonging to 14 families, were identified. Euterpina acutifrons and Oithona nana were the most common and abundant species. The Acartiids were represented by three species (Acartia clausi, A. tonsa and A. bifilosa) in autumn and one species in spring (A. clausi). The copepods diversity was significantly different between the two seasons showing high values at the entrance and the center of the bay in autumn 2015 and in the southern half of the bay in spring 2016. The copepod structure was characterized by 13 species at different degrees of contribution in autumn 2015. In spring 2016, only four species qualified as indicator species although their contribution was not significant. Given its large opening on the ocean, Cintra Bay benefits largely from the conditions of the oceanic environment, particularly the upwelling. This situation is likely to have an impact on the spatiotemporal variability of the composition and distribution of zooplankton, especially the copepods. Keywords: Cintra Bay, Zooplankton, Copepods, Diversity indices, Environmental parameter