Individual cloacal swabs of mallards (Anas) to isolate fluoroquinolone-resistant E. coli. PCR was used to detect specific antibiotic resistance genes. We found 9 E. coli isolates producing ESBL with bla genes: bla CTX-M-1 (6 isolates), bla CTX-M-9 plus bla TEM-1b (1 isolate), bla CTX-M-15 plus bla OXA-1 (1 isolate), and bla SHV-12 (1 isolate). In the isolate with bla CTX-M-15 , the gene aac(6)-Ib-cr was also detected. The bla genes were harbored by transferable plasmids of the IncN and IncI1 groups. Nine quinolone-resistant E. coli isolates with qnrS genes were found and characterized. There is considerable concern about antibiotic resistance in bacteria from humans and farm animals, but the spread of resistance into wider ecosystems has received much less attention (48). Usually, isolates of the common intestinal bacterium Escherichia coli are examined to detect antibiotic resistance in populations of wild animals. Wild birds are colonized with various strains of E. coli, including strains such as E. coli O157 that are pathogenic for humans (83). Fecal strains of E. coli resistant to antibiotics have been found at various prevalences in wild bird populations. In particular, bird populations sympatric to areas inhabited by people and areas with a high density of livestock were colonized with antibiotic-resistant E. coli strains possibly selected by the antibiotic practice in humans and domestic animals. Antibiotic-resistant E. coli isolates have been found in corvids (Corvus corone, C. frugilegus, C. macrorhynchos, Pica pica, and Pyrrhocorax pyrrhocorax) (3,46,48,53,74), house sparrows (Passer domesticus) (22, 61), house martins (Delichon urbica) (73), feral pigeons (Columba livia forma domestica) (68

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The aim of this paper was to assess the influence of diet on the concentrations of total mercury (HgTOT) in the eggs of aquatic birds. Trophic level was determined using stable isotopes (δ(15)N, δ(13)C). Analysis was carried out on eggs (laid in 2010-2012) belonging to two species of terns nesting at the River Vistula outlet on the Gulf of Gdansk and on herring gulls nesting both in Gdynia harbour and on the Vistula dam in Wloclawek. The results show that seafood diet causes the highest load of mercury, that which is transferred into terns eggs. The amounts of accumulated mercury obtained were found to be different in the particular egg components with Hgalbumen > Hgyolk > Hgmembrane > Hgshell. In the herring gull eggs, three stages of embryo development with varying levels of mercury were determined. It was observed that mercury received from the albumen and yolk was most effectively removed when developing embryo into down.

We compared the concentrations of 17 heavy metals and essential elements in post-hatching eggshells of two waterbirds, the obligate piscivorous great cormorant Phalacrocorax carbo (GCM) and the more omnivorous grey heron Ardea cinerea (GHR), breeding sympatrically in eight mixed colonies in Poland. We found significant inter-species and inter-colony differences in the levels of most of the elements. GHR had significantly higher concentrations of Al, which can be explained by its very low stomach pH: an acidic environment favours the release of Al compounds. Differences in Mn, Ni, Cu, Se and Hg concentrations can be attributed to the various contributions of fish and other aquatic organisms to the diet, and to the exploration of different habitats (GCM exclusively aquatic, GHR a wider range) and microhabitats (GCM, in contrast to wading GHR, dive for food, exploring the whole depth range of water bodies), differently exposed to contamination by those elements from sediments. Inter-colony differences were related to the level of industrialisation. We recorded higher levels of some elements in the eggshells (Fe, Mn in both species and Cr, Ni and Zn in GCM) collected in industrialised areas, which may be associated with the negative environmental impact of industrial areas.Electronic supplementary materialThe online version of this article (10.1007/s11356-018-3765-5) contains supplementary material, which is available to authorized users.