Large-scale research on seagrass-associated benthic fauna is very important for future regional marine conservation. In our study, we investigated spatial and latitudinal variation of benthic macroinvertebrate assemblages associated to Zostera noltei Hornemann, 1832 beds from five semi-enclosed coastal systems (SECSs) ranging from 23°N to 34°N along the Atlantic coast of Morocco. Overall, 17,320 individuals were reported as belonging to 96 taxa. The ecological community descriptors differ significantly at the level of the site. Specific richness showed an inconsistent significant pattern with latitude. The multivariate analyses of the assemblage’s composition showed 57% of total variation observed in benthic assemblages, while the PERMANOVA analysis confirmed that this variation is significant at the level of the site. According to DistLM results, variations in belowground biomass, and percentage of mud, were the important predictor variables explaining this variation along the large scale of the studied SECS. However, such patterns could be related to other factors such as habitat heterogeneity and regional, biogeographic, and anthropogenic factors. The present study marked the first attempt on broad-scale ecological research of seagrass beds in Morocco and offers baseline data for planning the broad-scale conservation of biodiversity in seagrass beds that remain suffering from multiple human-induced threats such as coastal developments and climate change.
Seagrass meadows exist in most shallow, sheltered, soft-bottomed marine coastlines and estuaries throughout the world and rank among the most productive systems in the ocean. Zostera noltei Hornemann is a small seagrass largely widespread in intertidal areas of Western Europe and North-West Africa, the Mediterranean Sea and in the Black Sea. In Morocco, intertidal Zostera noltei meadows were identified at six coastal ecosystems across c.a. 2500 km of its Atlantic coast (Tahaddart estuary, Moulay Bousselham, Sidi Moussa, Oualidia, Khnifiss lagoons and Dakhla Bay). The present work aimed at assessing the spatial and latitudinal variation of Z. noltei meadows by measuring the density of shoots, leaf biomass, root-rhizome biomass, number of leaf /shoot and the average length and width of leafs. Samples were conducted between December 2014 and January 2015, using a hand PVC corer (12.5 of diameter). When possible, a downstream and upstream comparison is performed in each site. Density of shoots fluctuated between 1972 and 9833 shoots m -2 . Leaves biomass varied between 32 and 259 gDW/m 2 and root-rhizome biomass oscillated between 21 and 314 gDW/m 2 . Number of leaves per shoot fluctuated between 2.47 and 3.4 leaf per shoot, the leaf length between 4.9 and 30.8 cm and the leaf width 0.6 and 2 mm. These results showed, on the one hand, a clear spatial variation across a downstream-upstream gradient in each site and, on the other hand, a latitudinal pattern in the biomass and morphometry of the Z. noltei meadows across the Atlantic coast of Morocco. Significant differences were evidenced for all variables (ANOVA, p<0.05). The root-rhizome biomass and density of shoots are higher southward while the number of leaves per shoot, leaf biomass and the average length and width of the leaves are greater northward. These results are compared with literature data from the distribution range of Z. noltei . Further analysis regarding the genetics, the associated benthic invertebrates and the sediment contamination are being performed and will increase the knowledge on such ecosystems and help in understanding their interaction with environment conditions.
The Marchica lagoon is the single lagoon on the Mediterranean coast of Morocco. Beside its ecological and socio-economic values, the lagoon is under pressure of a complex mixture of human-mediated stressors (urbanization, pollution, overfishing, tourism, etc.). Nowadays, many institutional efforts have been undertaken to establish a sustainable management plan of the lagoon in the context of an Integrated Coastal Zone Management (ICZM) approach. Thus, understanding how these stressors impact upon ecological status and ecosystem services is a sound step for any efficient integral management. Based on sampling performed on June 2014, the present work aimed at assessing the ecological quality status (ES) of the northern part of the lagoon using Cymodocea nodosa (Ucria) Ascherson meadows and benthic macrofauna. 16 stations (11 with C. nodosa and 5 on bare sediment) were sampled using a Van Veen grab. Preliminary results showed differences between stations. Shoots biomass fluctuated between 8.02 and 61.2 g dw m-2 while the roots-rhizomes biomass oscillated between 10.8 and 235.5 g dw m-2. The root-rhizome and leaf biomass ratio revealed high values (up to 10.8) in the central sector suggesting a potential nutrient enrichment.Benthic macrofauna revealed the presence of 90 species belonging to six zoological groups and dominated by crustaceans, molluscs and polychaetes. The assessment of the ecological quality status, based on benthic macrofauna, was evaluated using Biotic Indices (AMBI, M-AMBI, Benthix, BITS). The results showed partial agreement between single index-derived ES and underlined the dependency of these biotic indices on the habitat characteristics, on the one hand, and the necessity to define specific reference conditions to the Marchica lagoon.
Abstract Coastal lagoons are considered as one of the most productive ecosystems worldwide but are also vulnerable to the growing human-made stressors. This study aimed at assessing, for the first time, the ecological status of the Oualidia lagoon (Atlantic coast of Morocco) using benthic macroinvertebrates as bioindicators. An integrative ecological monitoring approach based on spatial diversity patterns of species assemblages (examined using taxonomic indices, structural trophic guilds as indicators of the functional biodiversity, and marine biotic indices) in relation to sedimentary and hydrological descriptors was performed. Results showed that hydrodynamic conditions, represented by intra-lagoon currents and the watershed, govern the entire sediment distribution within the lagoon and establish a longitudinal downstream-upstream gradient and transverse right-left banks, which explained 66% of the total variation observed in benthic assemblage composition. Seagrass meadows affect positively the abundance of dominant species but do not support high diversity. Overall, macrozoobenthos spatial pattern consists in modification of the relative abundance of species, independently of species composition. The average score of the ecological classes obtained from five biotic indices (AMBI, BENTIX, H’, MAMBI and ITI) showed an acceptable status of the benthic assemblages. This integrated analysis resulted in a holistic view of the benthic-ecosystem that will serve in implementing an ecosystem-based approach to the management of the Oualidia lagoon.
This study presents an assessment of the diversity and spatial distribution of benthic macrofauna communities along the Moulay Bousselham lagoon and discusses the environmental factors contributing to observed patterns. In the autumn of 2018, 68 stations were sampled with three replicates per station in subtidal and intertidal areas. Environmental conditions showed that the range of water temperature was from 25.0 °C to 12.3 °C, the salinity varied between 38.7 and 3.7, while the average of pH values fluctuated between 7.3 and 8.0. In vegetated habitats, biomass values of the seagrass Zostera noltei Hornemann ranged between 31.7 gDW/m² and 170.2 gDW/m² while the biomass of the seagrass Ruppia cirrhosa (Petagna) Grande between 54.2 gDW/m² and 84.7 gDW/m². Sediment analyses showed that the lagoon is mainly composed of sandy and silty sediments. We recorded 37,165 individuals of macrofauna distributed in 63 taxa belonging to 50 families, with a mean abundance value of 4582.8 ind/m² and biomass average of 22.2 g/m². Distance-based linear modeling analysis (DISTLM) identified sediment characteristics, water parameters and habitat type (biomass of Z. noltei) as the major environmental drivers influencing macrozoobenthos patterns. Our results clearly revealed that the hydrographic regime (marine and terrestrial freshwater), sediment distribution and characteristics and the type of habitat (vegetated vs. unvegetated substrate) are the key factors determining the species composition and patterns of macrozoobenthos assemblages.
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