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  • Int.J.Curr.Microbiol.App.Sci (2014) 3(3): 675-694

    675

    Original Research Article

    Spatial and temporal variation of faecal pollution indicators (Escherichia coli and faecal streptococci) and physico-chemical parameters at the Oualidia

    lagoon and its watershed (Morocco)

    N.Hassou1, M.Maanan2, M.Hennani1, B.Zourarah3, and O.Assobhei1

    1Marine biotechnology and Environment laboratory-REMER, Biology department, Faculty of Sciences, 24000 El Jadida, Morocco

    2 Laboratoire Golittomer, UMR 6554 LETG, Universit de Nantes. Nantes, France. 3 Marine Geosciences laboratory-REMER (URAC 45), Earth Sciences department, Faculty of

    Sciences, 24000 El Jadida, Morocco *Corresponding author

    A B S T R A C T

    Introduction

    The Oualidia lagoon is one of the largest coastal wetlands in Morocco. Mainly in relation to its ornithological importance, this site has been classified as a site of Biological and Ecological Interest (SIBE), through the master plan of Protected Areas of Morocco, and as a Ramsar site since 2005.This site of international value is a

    migratory stopover and winter refuge appreciated by various shorebirdspecies. It is characterized by a warm temperate climate and an average rainfall varying according to the natural fluctuations in rainfall patterns. Along its coastal strip made up of the wetland area of Oualidia, different water masses are juxtaposed: the

    ISSN: 2319-7706 Volume 3 Number 3 (2014) pp. 675-694 http://www.ijcmas.com

    K e y w o r d s

    Escherichia coli; faecal streptococci; Oualidia lagoon; Atlantic coastline.

    The spatio-temporal variations of four physico-chemical parameters (temperature, salinity, pH and turbidity) and content in water of Escherichia coli (E. coli) and faecal streptococci (FS) were studied between July 2010 and July 2011 at the Oualidia lagoon and its watershed in relation to the discharge of domestic and agricultural wastewater. The analysis of the spatio-temporal variability, performed by principal component analysis (PCA) combining physico-chemical and microbiological parameters, revealed a significant seasonal variation (at p 0.05) were observed for the watershed waters. Results show two types of pollution (i) urban pollution due to the intense tourist activity in summer and (ii) agricultural pollution due to leaching and infiltration of agricultural practices around the lagoon in the rainy season. The observations in this study can be useful for implementing faecal pollution management strategies and for predicting faecal contamination as a function of meteorological conditions.

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    groundwater, theOualidia lagoon waters, and the oceanic waters. This juxtaposition enables flow transfers of material within this ecosystem.The lagoon of Oualidia is experiencing a malfunction related to confinement, pollution by metals and land cover (Zourarahet al., 2007; Maanan, 2008; Hennaniet al., 2012; Maanan et al., 2013).

    Local land use can lead to vegetation damage, soil, water and land degradation, as well as local and global climate change, either directly or indirectly (Mhamdiet al., 2010; Maanan et al., 2013; Lu et al., 2013).

    Sewage discharges into the aquatic environment and soil leaching sometimes bring very large quantities of bacteria of faecal origin. Among these bacteria, some are pathogenic and are therefore a health concern whose importance depends on the level of contamination and on the water use (drinking water, swimming, etc.).Research into this kind of contamination is carried out on faecal contamination reference bacteria Escherichia coli (E. coli) and faecal streptococci (FS), whose high concentration may indicate the presence of pathogenic bacteria or viruses in the environment (Kay et al., 2010).

    Due to its economic and tourism importance, the Oualidia lagoon has been the subject of several microbiological, hydrological and ecological (Maanan, 2008),geological and sedimentary studies (Maanan et al., 2013) aiming to establish its current state of functioning and to characterize the different areas of this paralic environment.

    The anthropogenic pollution may restrict the potential of the lagoons for shellfish

    farming and harvesting because ofthe sanitary risk presented by the consumption of these contaminated shellfish, raw or lightly cooked (Zourarahet al.,2009; Gourmelonet al., 2010; Kalloulet al., 2012).Therefore, national and international standards have been established which are based essentially on the level of faecal pollution indicators (Escherichia coli and faecal streptococci).

    Faecal coliforms, and especially Escherichia coli, are considered good indicators of faecal water pollution (Schoen et al., 2011; Oladeindeet al., 2013). Their presence in water signifies recent contamination by faecal material, as their survival in the marine environment is limited. The presence of faecal streptococci, especially Streptococcus faecalis which is exclusively of animal origin, is another indicator of faecal contamination. These bacteria have the advantage of being resistant in water longer than faecal coliforms (Montielet al., 2013).

    In order to enable the authorities to establish a program to clean up the lagoon based on the real sources of pollution, our study has set the following objectives: (1) to assess the concentrations of faecal indicators bacteria E. coli and FS contained in the lagoon and watershed watersduring an annual cycle (July 2010-June 2011), (2) to study the spatio-temporal distribution of these indicators of contamination depending on the land use of the watershed, (3) to link the variations of the microbiological parameters (E. coli and faecal streptococci) with the physico-chemical parameters (temperature, pH, salinity and turbidity) and the variability of practices resulting from the different land uses in the watershed using the statistical method of PCA (Principal

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    Component Analysis) as well as the descriptive statistical analysis SPSS 17.0. Materials and Methods

    Study site

    TheOualidia lagoon is located on the Moroccan Atlantic coast in the province of Sidi Bennour, 168 km south of the city of Casablanca, and extends parallel to the coast for a distance of about 8 km long and 0.5 km wide (Figure1).

    The communication of the lagoon with the ocean is ensured by two passages located downstream. It extends upstream in the form of a channel, 7 km in length, up to the dike separating the lagoon from the salant tides. Sources of fresh water are distributed along the lagoon, resulting in a dilution of surface water, along a gradient of desalting from downstream to upstream. The main activities are agriculture (essentially cereals and vegetables) and cattle rearing (practiced by more than 90% of the population), shellfish farming (15%) and tourism. The population density has rapidly increased from 7741 inhabitants in 1971 to 15430 inhabitants in 2004 (http://www.statistic.gov.ma/), polluting and non-polluting human activities have been established in the lagoon, various marine activities for boating, bathing, camping, and other human activities have increased, and rapid urbanization of the region has occurred in recent years. In addition to the current population, there is an important influx of tourists in the summer, increasing the population by 54000 (http://www.statistic.gov.ma/).

    Land use changes can have significant effects on runoff volume and consequently faecal bacteria input. Differences in land use in Oualidia lagoon and its watershed

    are expected to produce different kinds of contamination. For example, aquaculture activities, remains farming of Pacific cupped oysters (Crassostreagigas), may promote the increase of organic enriched-sediment fluxes, whereas faecal bacteria contamination might result from agricultural activities, sewage dumping from urban areas and tourism activities in the lagoon. At present, most wastes waters discharged to Oualidia lagoon are not treated, which means that the contaminant loads might be reduced only by natural processes.

    The hydrological regime of the lagoon is primarily subject to the rhythm of the tides. During spring tides, the water flow has an average speed of about 0.46 m/s and a maximum speed of around 0.77 m/s; the filling time during the flow is 7 h 25 min and that of emptying is 5 h during the backflow. During neap tides, flow velocities are lower, in the range of 0.1 to 0.2 m/s, and the times of filling and emptying are 4 h 25 min for the flow and 8 h in the ebb,respectively (Orbi et al., 2008). In addition, the hydrological regime of Oualidia lagoon is subject to the action of upwelling which affects the whole area, especially in summer (Makaouiet al., 2005).

    The supply of fresh water to the lagoon occurs only upstream by means of a freshwater effluent, which maintains a certain gradient of desalting at low tide, while downstream it occurs via small resurgences.

    Because of its position between two hills forming its watershed, the Oualidia lagoon is a confluence of runoff water during rainfall in the region. On the other hand, faecal contamination (during the spreading of animal manure) and wastewater

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    infiltration from septic tanks are the major mainland inputs to the lagoon (El Himeret al., 2013). The maximum rainfalls recorded during our study period were 187 mm in November and 80 mm in January with an average of 46 mm.

    Sampli