Recent impact of DDT contamination on Black Stork

Authors: Māris Strazds HansGünther Bauer Ülo Väli Agnese Kukāre Vadims Bartkevičs

Publish Date: 2015/07/01

Volume: 156, Issue: 1, Pages: 187-198

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Abstract

The contamination with DDT 111trichloro22bis4chlorophenylethane and its breakdown products as a potential cause of population decline of Black Stork has been studied in Latvia since 2008 In order to test if contamination is local or widely distributed we collected failed eggs from nests also in Estonia Belarus Poland Czech Republic Germany and Belgium DDT or its breakdown products were found in all analysed eggs The ratio of pp′DDT as a proportion of all DDT products increased during the years of our research Since the Black Stork has so far not been mentioned as a species affected by DDT we do not have information about its critical contamination effect levels However we also present data suggesting that DDT contamination might have affected Black Stork historically Current data suggest that the reduction of eggshell thickness has not yet reached the levels described as critical for other affected species However we found a significant reduction of egg volumes which in turn negatively affects hatching as eggs below a threshold size fail to hatch The ratio of small eggs versus normal eggs has increased by almost 10  in recent years and is strikingly higher as compared to the preDDT period There is also a significant correlation between eggs of reduced size and their respective DDE 11bis4chlorophenyl22dichloroethene valuesFor advice on various aspects of the manuscript our thanks go to Dr Jānis Priednieks Latvia Dr Björn Helander Sweden Dr Charles J Henny USA Dr Tony Fox Denmark Dr Andrew Gosler UK and Dr Peter Becker Germany for assistance in field work to Helmuts Hofmanis Valters Pranks Jānis Ķuze Latvia Urmas Sellis Estonia Jan Prochazka Vaclav Beran František Pojer Czech Republic Carsten Rohde Germany Dr Piotr Zielinski Poland and Gerard Jadoul Belgium for help and significant input into various pathology and contamination research related issues to Santa Avotiņa Grīnblate Dr Ilze Matīse Lauma Latkovska and Dace Bērziņa For institutional assistance and financial support in various stages of the work we thank the European Social Fund University of Latvia Latvian Ornithological Society Environment Protection Fund of Latvia LVAF The Stork Foundation Germany Estonian Ministry of Education and Research grant IUT211 and several individual donors particularly Agris Krusts Dace Rukšāne Ģirts Zembergs Latvia and Marcus Walsh Finland Herewith we confirm that inspection of stork nests collection of failed eggs and all treatments of juveniles measuring and ringmarking were carried out with respective permits granted by national authorities

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