Taxonomic diversity and structure of the molluscan fauna in Oualidia lagoon (Moroccan Atlantic coast)

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Origin and potential ecological risk assessment of trace elements in the watershed topsoil and coastal sediment of the Oualidia lagoon, Morocco

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Macroinvertebrate structure and trophic-functional organization in relation to environmental conditions in Dakhla Bay (southeast Morocco)

International audienceBenthic macroinvertebrate assemblages and environmental conditions were studied in Dakhla Bay (Morocco) to (1) characterize the macroinvertebrate composition and spatial distribution, (2) provide a species inventory, and (3) to assess the key environmental variables driving the observed patterns. We identified 9,288 individuals from 67 species. The most dominant taxa were molluscs, polychaetes and crustaceans. The most abundant species were (in this order) Peringia ulvae, Bittium reticulatum, Ophelia rathkei, Mesalia mesal and Maldane sarsi, while the most frequent were (in this order) M. sarsi, Ampelisca sp., Cyathura carinata, Naineris laevigata and Chondrochelia savignyi. The spatial distribution pattern was mainly driven by sediment grain-size and Chlorophyll-a, with hydrodynamics playing also a key role. This gives rise to a structure characterized by three different station clusters, well identified in the Hierarchical Ascending Classification analysis based on abundances, which correspond to a large moderately disturbed assemblage in the centre of the bay, a more disturbed assemblage in the extremes and a transition assemblage in between

Community Structure and Spatial Patterns of Soft-Bottom Macrozoobenthos in Oualidia Lagoon, Moroccan Atlantic

International audienceThe paper analyses the composition, structure and spatial organization of the soft-bottom macrozoobenthos inhabiting Oualidia lagoon (Moroccan Atlantic coasts), as well as their relationships with the main environmental variables. Material for the study was collected from 43 stations in winter 2013. A total of 56 taxa belonging to 6 phyla were recorded. Species diversity showed the highest values for molluscs, crustaceans and polychaetes. We used a Hierarchical Ascending Classification and a non-Metric Multidimensional Scaling to characterize the macrozoobenthos of the lagoon. We identified three groups of stations according to the outer, middle and inner part of the lagoon, hosting arranged from the outer -most to inner-most areas of the lagoon. The trophic structure of the macrozoobenthos was dominated in density by deposit-feeders (88.1%) and species richness by carnivores (20%) and detritivorous (20%). The BIO-ENV analysis showed that the combination of granulometry, salinity and temperature were the major factors controlling the spatial distribution of the macrozoobenthos in the Oualidia Lagoon

Analysis of the structural characteristics and spatial organization of macrobenthic fauna in Oualidia lagoon, Morocco

Este artículo contiene 13 páginas, 9 figuras, 3 tablas.Morocco is a very rich country in terms of wetlands, including bays, estuaries, lagoons, lakes, and rivers, among others. However, many of them need to be well managed and better exploited, thus requiring baseline descriptive studies to assess faunal patterns and trends. Oualidia lagoon is not an exception. In fact, the studies conducted to date in the lagoon mainly focused on its oceanographic features and aquaculture capacities. The present paper presents the first study on the whole macrofaunal assemblages of Oualidia lagoon, having as main objectives analyze the composition and structure of the assemblages, as well as their relationships with the main environmental variables explaining their spatial distribution variability in the enclosed ecosystem of the Oualidia coastal lagoon. The benthic macroinvertebrates of Oualidia lagoon were studied in summer 2013 based on 43 stations spread over the whole lagoon by using a Van Veen grab. Two replicate samples were collected for macrobenthos and one additional replicate for sediment analyses at each station. Also, single water salinity and temperature measurements were recorded at each station. Fifty-one species from seven different taxa were recorded, among which mollusks (37%), polychaetes (25%) and crustaceans (25%) dominated in terms of species number. Peringia ulvae, Abra alba, Sphaeroma serratum, Cerastoderma edule and Corophium sp. accounted for 88% of total abundance. The benthos was structured along a downstream–upstream gradient, showing three assemblages, named according to the IndVal index: (1) Diopatra cf. marocensis, (2) Peringia ulvae, and (3) Cerastoderma edule, while the main factors driving their distribution were granulometry and salinity. The Biotic and Environmental analysis showed that the combination of granulometry and salinity was the major factors controlling the spatial distribution of the macrozoobenthos in the Oualidia Lagoon.FE, AE, MT, MM, HZ were partly funded by a research program on coastal resources of the LERL/DRH-Casablanca (National Fisheries Research Institute). DM received funding from the Consolidated Research Group on Marine Benthic Ecology, Generalitat de Catalunya (http:// agaur. gencat. cat), grant 2017SGR378, and the Agencia Estatal de Investigación (AEI) (http:// www. cienc ia. gob. es/ portal/ site/ MICINN/ aei), European Regional Development Funds (FEDER) (https:// ec. europa. eu/ regio nal_ policy/ en/ fundi ng/ erdf/), grant CTM2017–88080 / PopCOmics.Peer reviewe

Polychaete diversity and assemblage structure in the Oualidia Lagoon, Moroccan Atlantic coast

International audienceThe polychaete assemblages inhabiting the coastal waters of the Oualidia lagoon were studied during winter 2013 and summer 2013. Taxonomic composition and diversity were determined at 43 sample sites. Among the 13 species of polychaetes recorded, 10 were newly reported for Oualidia lagoon. Hediste diversicolor and Capitella sp. were the most abundant taxa in both seasons. Temperature and salinity were higher, and chl-a and OM were lower, in summer than in winter. The structure of the polychaete assemblages was characterized by forming three main clusters, either based on sampling stations or on polychaete species. These clusters were organized according to a downstream gradient, with the stations having fine sediments and a H. diversicolor assemblage in the inner lagoon being replaced by stations with medium grain-sized sediment and a Capitella sp. assemblage in the mid-lagoon, which were in turn replaced by stations having sandy sediments and assemblages dominated by Glycera alba (winter) and P. africana (summer) in the areas closer to the lagoon inlets. The shift was, in fact, from a classical, brackish, lacunar assemblage to two different, temporal aspects of a marine assemblage (close to the inlets), with a transition assemblage in between. This corresponded with a typically paralic spatial structure whose main descriptors responded to a confinement gradient. Despite the absence of a river, the organization of the polychaete assemblages closely resembled that of an estuarine system, with the tidal regime playing a major driving rol

Environmental and ecological risk of heavy metals in the marine sediment from Dakhla Bay, Morocco

International audienceHeavy metal assessment in Dakhla Bay (Atlantic coast) was carried out using different environmental and ecological indices. Heavy metal concentrations were measured using ICP–AES and were compared with consensus-based sediment quality guidelines. The distribution of heavy metal concentrations varies for the three groups: (i) lead distribution is dominated by its associations with copper and chromium. These elements have the same source, most probably related to anthropogenic activities. (ii) Nickel, zinc and cobalt are associated with aluminium and iron indicating their terrigenous origin (natural content), and (iii) cadmium concentration is related to upwelling currents. This paper systematically studied the distributions and pollution levels of heavy metals in sediment in the coastal areas in Dakhla Bay, which is of scientific significance, to discuss the changing rules and the affecting factors of the harmful heavy metals and can be adopted for reference to other coastal areas

Spatial and temporal variability in distribution, diversity, and structure of the polychaete assemblages from Dakhla Bay (Atlantic coast of South Morocco)

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