title: Little Egret (Egretta garzetta) as a bioindicator of trace element pollution in Tunisian aquatic ecosystems.
abstract: The Little Egret, Egretta garzetta, has breeding colonies in the island of Chikly (in the lake of Tunis) and in Thyna saltpans (in the gulf of Gabès), two important Tunisian wetlands that are strongly affected by anthropogenic activity. Here, we used E. garzetta chick feathers for environmental monitoring of breeding grounds of this species. Since trophic ecology is fundamental when interpreting contamination levels, our approach combined both trace-element (Hg, Pb, Cd, and Se) and stable-isotope analysis of δ13C, δ15N, and δ34S. Hg, Se, and δ15N levels were higher in specimens collected on Chikly than in Thyna. These observations highlight the degree of eutrophication of the lake of Tunis. Yellow-legged gulls (Larus michahellis) breeding in the same areas also feeds in the lake and attains similar concentrations of Hg and Se. In Thyna, egrets and gulls exploit distinct foraging habitats, as demonstrated by stable isotope analysis. The highest Hg and Se concentrations were found in Thyna. This result is consistent with greater exploitation of marine resources from the gulf of Gabès.
authors.affiliation: Department Biologia Animal, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, 08028, Barcelona, Spain. aida_abdennadher@hotmail.com
authors.forename: Aida
authors.initials: A
authors.lastname: Abdennadher
authors.forename: Francisco
authors.initials: F
authors.lastname: Ramírez
authors.forename: Mohamed Salah
authors.initials: MS
authors.lastname: Romdhane
authors.forename: Xavier
authors.initials: X
authors.lastname: Ruiz
authors.forename: Lluis
authors.initials: L
authors.lastname: Jover
authors.forename: Carolina
authors.initials: C
authors.lastname: Sanpera
mesh_terms: D000818:Animals; D001717:Birds / Q000378:metabolism*; D004784:Environmental Monitoring / Q000379:methods*; D007854:Lead / Q000032:analysis / Q000378:metabolism; D008628:Mercury / Q000032:analysis / Q000378:metabolism; D012643:Selenium / Q000032:analysis / Q000378:metabolism; D014131:Trace Elements / Q000032:analysis* / Q000378:metabolism; D014416:Tunisia; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism; D014881:Water Supply / Q000032:analysis
chemical_list: D014131:Trace Elements; D014874:Water Pollutants, Chemical; D007854:Lead; D008628:Mercury; D012643:Selenium