title: Pesticides in Ichkeul Lake-Bizerta Lagoon Watershed in Tunisia: use, occurrence, and effects on bacteria and free-living marine nematodes.
abstract: This study aimed to identify the most commonly used agricultural pesticides around Ichkeul Lake-Bizerta Lagoon watershed. First survey of pesticide use on agricultural watershed was performed with farmers, Regional Commissioner for Agricultural Development, and pesticide dealers. Then, sediment contamination by pesticides and response of benthic communities (bacteria and free-living marine nematode) were investigated. The analysis of 22 active organochlorine pesticides in sediments was performed according to quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, biodiversity of indigenous bacterial community sediment was determined by terminal restriction fragment length polymorphism (T-RFLP), and free-living marine nematodes were counted. The results of the field survey showed that iodosulfuron, mesosulfuron, 2,4-dichlorophenoxyacetic acid (2,4 D), glyphosate, and fenoxaprops were the most used herbicides, tebuconazole and epoxiconazole the most used fungicides, and deltamethrin the most used insecticide. Sixteen organochlorine pesticide compounds among the 22 examined were detected in sediments up to 2 ppm in Ichkeul Lake, endrin, dieldrin, and hexachlorocyclohexane being the most detected molecules. The most pesticide-contaminated site in the lake presented the higher density of nematode, but when considering all sites, no clear correlation with organochlorine pesticide (OCP) content could be established. The bacterial community structure in the most contaminated site in the lake was characterized by the terminal restriction fragments (T-RFs) 97, 146, 258, 285, and 335 while the most contaminated site in the lagoon was characterized by the T-RFs 54, 263, 315, 403, and 428. Interestingly, T-RFs 38 and 143 were found in the most contaminated sites of both lake and lagoon ecosystems, indicating that they were resistant to OCPs and able to cope with environmental fluctuation of salinity. In contrast, the T-RFs 63, 100, 118, and 381 in the lake and the T-RFs 40, 60, 80, 158, 300, 321, and 357 in the lagoon were sensitive to OCPs. This study highlighted that the intensive use of pesticides in agriculture, through transfer to aquatic ecosystem, may disturb the benthic ecosystem functioning of the protected area. The free-living marine nematodes and bacterial communities represent useful proxy to follow the ecosystem health and its capacity of resilience.
authors.affiliation: Laboratory of Environment Biomonitoring, Faculty of Sciences of Bizerta, University of Carthage, 7021, Zarzouna, Tunisia. fida.bensalem@univ-pau.fr.|Equipe Environnement et Microbiologie, MELODY Group, UMR CNRS IPREM 5254-IBEAS, Université de Pau et des Pays de l'Adour, Pau cedex, France. fida.bensalem@univ-pau.fr.|Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Pau cedex, France. fida.bensalem@univ-pau.fr.
authors.forename: Fida Ben
authors.initials: FB
authors.lastname: Salem
authors.affiliation: Laboratory of Environment Biomonitoring, Faculty of Sciences of Bizerta, University of Carthage, 7021, Zarzouna, Tunisia.
authors.forename: Olfa Ben
authors.initials: OB
authors.lastname: Said
authors.affiliation: Laboratory of Environment Biomonitoring, Faculty of Sciences of Bizerta, University of Carthage, 7021, Zarzouna, Tunisia.
authors.forename: Patricia
authors.initials: P
authors.lastname: Aissa
authors.affiliation: Laboratory of Environment Biomonitoring, Faculty of Sciences of Bizerta, University of Carthage, 7021, Zarzouna, Tunisia.
authors.forename: Ezzeddine
authors.initials: E
authors.lastname: Mahmoudi
authors.affiliation: Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM UMR 5254 CNRS, Université de Pau et des Pays de l'Adour, Pau cedex, France.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Monperrus
authors.affiliation: IRD, UMR-LISAH (IRD-INRA-SupAgro), Bat 24, 2 place Viala, 34060, Montpellier cedex 01, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Grunberger
authors.affiliation: Equipe Environnement et Microbiologie, MELODY Group, UMR CNRS IPREM 5254-IBEAS, Université de Pau et des Pays de l'Adour, Pau cedex, France.
authors.forename: Robert
authors.initials: R
authors.lastname: Duran
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid; D000383:Agriculture; D000818:Animals; D001419:Bacteria / Q000187:drug effects*; D004026:Dieldrin; D017753:Ecosystem; D006843:Hydrocarbons, Chlorinated / Q000032:analysis; D007306:Insecticides / Q000032:analysis; D060106:Lakes / Q000737:chemistry; D009348:Nematoda / Q000187:drug effects*; D010575:Pesticides / Q000032:analysis; D014416:Tunisia; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D006843:Hydrocarbons, Chlorinated; D007306:Insecticides; D010575:Pesticides; D014874:Water Pollutants, Chemical; D015084:2,4-Dichlorophenoxyacetic Acid; D004026:Dieldrin
keywords: Bacterial community structure; Bacterial diversity; Organochlorine pesticides; Resistant; Sediment; Sensitive; Survey; T-RFLP