title: Intra-clutch and inter-colony variability in element concentrations in eggshells of the black-headed gull, Chroicocephalus ridibundus, in northern Poland.
abstract: Eggshells are good bioindicators of environmental contamination, and therefore, the concentrations of 17 trace elements in 87 eggshells of black-headed gulls, Chroicocephalus ridibundus, were determined in five breeding colonies in an area dominated by farmland in northern Poland. The intra-clutch variability in the eggshell concentrations of heavy metals and other elements was also investigated, and the concentrations of the elements showed the following pattern: Ca > Mg > Sr > Fe > Zn > Al > Cr > Se > Mn > Cu > Pb > As > Ni > Mo = V > Sc > Cd. The concentrations of Fe, Al, and Mn decreased with the order in which the eggs were laid, but Sr concentrations increased. In contrast, the concentration of Cu significantly increased with the laying date. The concentrations of all elements significantly differed among the studied colonies; the highest concentration of eight elements was found in the eggshells from the Kusowo colony, which may have resulted from the intensive use of fertilizers, manure, and slurry in the surrounding agricultural region. The concentrations of Mg, Sr, and Zn in the eggshells from Skoki Duże were higher than those of the other studied colonies, which may have occurred because the gulls were nesting in a functioning gravel pit; soil and the parent rock are natural reservoirs of these elements. The observed element levels indicate that the environment where the black-headed gull eggs were formed, i.e., primarily near the breeding colonies, remains in a relatively unpolluted state, which was reflected by the low levels of Cd, Ni, and Pb and the lack of measurable levels of Hg.
authors.affiliation: State School of Higher Education in Chełm, Pocztowa 54, 22-100, Chełm, Poland. ignacyk@autograf.pl.
authors.forename: Ignacy
authors.initials: I
authors.lastname: Kitowski
authors.affiliation: Department of Zoology and Landscaping, University of Sciences and Technology, Kordeckiego 20, 85-225, Bydgoszcz, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Indykiewicz
authors.affiliation: Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290, Lublin, Poland.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Wiącek
authors.affiliation: Department of Vertebrate Ecology and Zoology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Jakubas
mesh_terms: D000818:Animals; D046091:Charadriiformes; D004528:Egg Shell / Q000737:chemistry*; D004784:Environmental Monitoring; D019216:Metals, Heavy; D011044:Poland; D014131:Trace Elements
chemical_list: D019216:Metals, Heavy; D014131:Trace Elements
keywords: Contamination; Eggshells; Heavy metals; Waterbirds