Reproductive cycle of Scrobicularia plana (da Costa, 1778) (Bivalvia: Semelidae) in two Moroccan lagoons: Khnifiss and Oualidia

Volume: 30Start Page: 97End Page: 10

Recovery of an Estuarine Ecosystem after the Stopping of Wastewater Discharge: Intertidal Macrobenthic Community Characterization in the Estuary of Oued Souss (Southwestern Morocco)

The communities of benthic macroinvertebrates, living in the estuary of Oued Souss (Agadir Bay, Morocco), were studied in parallel with the changes that this ecosystem had underwent after the stopping of pollution, caused by untreated wastewater discharge which occurred in November 2002. Three campaigns were undertaken during the summer season. Two of them were carried out while the estuary was receiving wastewater discharge in 2001 and 2002. The 2003 campaign was carried out after the cessation of the pollution. The intertidal macrobenthic fauna shows a similar faunal composition for both seasons during the period when the ecosystem was receiving wastewater discharge. During this period, Hydrobia ulvae was the dominant species, followed by Hediste diversicolor and Scrobicularia plana in decreasing order. In 2003, the number of individuals harvested was significantly larger compared to the period when the ecosystem received wastewater. For the dominance of species, H. diversicolor was dominanted, followed by H. ulvae, Cerastoderma edule, and S. plana in decreasing order. However, in both periods: before and after the end of wastewater discharge, the phylum of mollusks is dominant, followed by that of Annelids and Crustaceans. The study of the coenotic affinity between settlements of different radials allowed us to separate 2–3 groups of radials in 2001 and 2002, respectively, and 3 groups after stopping discharges in the estuary. The specific richness was greater in the year following the end of discharges (22 species in 2003 instead of 14 found during the pollution period: 2001–2002). The longitudinal distribution of the species living in this site in 2001 and 2002 became wider in 2003 and average biomass, determined by the study of the ash-free dry weight, became clearly greater (20.46 g/m2 in 2003; and 15.54 g/ m2 or 15.84 g/ m2 in 2001 or 2002 respectively). This investigation allowed us to acquire a qualitative (species list, species richness) and quantitative (abundance, biomass, species density) database of intertidal benthic macrofauna of the Oued Souss estuary. It represents a reference state. It responds to the requests for information about the quality of the environment immediately after the cessation of wastewater discharge and could serve as a basis for conducting impact studies later

Medium optimization for exopolysaccharides production by Bacillus Zhangzhouensis BZ 16 strain isolated from Khnifiss Lagoon

The increased demand for natural polymers for diverse industrial applications in last years has led to a renovated interest in exopolysaccharides (EPS) production by microorganisms. Ecological roles of EPS especially for those isolated from extreme habitats such as hypersaline ponds have been reported in several studies. A moderate halophilic strain producing exopolysaccharide (EPS) has been isolated earlier. However, the EPS production of the strain (2 g/L) was relatively low to exploit it at the industrial level. In the present work, the strain was identified as Bacillus zhangzhouensis and named as BZ 16 and the optimal medium was studied to boost the EPS production. Maximum EPS production was obtained in medium with 125 g/L sucrose, 30 g/L yeast extract. Phosphate source inhibited EPS production even if it increased the growth. Under optimal medium composition, EPS was produced at 12.37 g/L, which was 6 times greater than the production yield achievable without optimizing conditions

State Diagnosis of Macrozoobenthic Biodiversity in the Intertidal Zone of the Sandy Coast of Taghazout (Southwestern of Morocco)

The present work is a part of the impact study of the tourist resort "Taghazout Bay" installation on the coast of Taghazout (North of the Agadir bay). The purpose of this study was to assess the initial state of the macrozoobenthic structure present in the intertidal sands at the three study stations over the 2016 and 2017 seasons. The biological approach was accompanied by the study of some physico-chemical parameters of the seawater (temperature, pH, salinity and dissolved oxygen) and the study of the sediment (grading structure, classification, and contents in organic matter). PCA analysis identified a perfect correlation between the physico-chemical parameters. The sediment contains three grading classes only (medium sand, fine sand, and very fine sand), very well classified with normal proportions of organic matter. The study of intertidal benthic macrofauna of the sandy substrate shows ten species and spatiotemporal variations with a clear dominance of the Donax trunculus bivalve species. The authors noticed – from the DIMO model – that the variation profile of the spring and summer (2016 and 2017) shows a community dynamics called "Diversity type". In winter and in autumn, they are known as the "Evenness type". The rank-frequency diagram explains that the benthic community of Taghazout sandy coast exists in the stage "Pioneer 1". The ascending hierarchical clustering gave three logical gatherings of seasons. The faunistic structure of this benthic community revealed the M>C>P shape. The authors also noticed that there is diversity in regimes in this ecosystem