Browsing by Subject "common eider"

This licentiate thesis includes a literature review and a research section. The populations of common eiders (Somateria mollissima) in the Baltic Sea and Finland have decreased. Still, the number of eiders nesting on the Bengtskär islet in the outer archipelago of Finland has been steadily increasing. In the literature review, the reader is first introduced to the biology of the common eiders and the situation of the Bengtskär eiders, after which the microbes and intestinal parasites that threaten the health of common eiders are discussed. The aim is to find out why eiders have died in Bengtskär between 2019 and 2021, and thus to increase the knowledge of veterinarians, biologists, and other interested parties about the health status of Bengtskär eiders. We hypothesize that the results will not be supposed to provide a single explanatory factor for the death of all birds, as no epidemics or mass deaths of eiders have been found in the area in these years. Another hypothesis is that we found Polymorphus minutus acanthocephalans in the intestines of several birds. The research material consists of 35 common eiders collected in 2019–2021, found dead in the Bengtskär islet. The birds have been stored at –20 °C before the examinations. The birds collected in 2019 were examined at the turn of 2019–2020 and the rest in January 2022. Necropsy included records of macroscopic findings and histological examinations and was performed by a pathologist. The eiders were also subjected to bacteriological cultures and, if necessary, additional studies to determine the bacterial species. Adult birds were examined for selected viruses and intestinal parasites using PCR. The pathologist has given the eiders diagnoses that probably explain the individual's death. The results show that the most common cause of death was bacterial infection (32,3 %), which was, however, limited only to ducklings (10/18) and unhatched fetuses (2/5). In full-grown birds, no growth was found in bacterial cultures and all virus tests were PCR-negative. We found three different intestinal parasites from the eiders: Profilicollis sp. acanthocephalan, Schistocephalus solidus tapeworm, and Echinostoma sp. trematoda. The majority (71,9 %) of the birds were in good or very good nutritional status, of these there were 15 ducklings and four fetuses. 62,9 % of all birds were females. In most ducklings and fetuses, death was probably caused by a bacterial infection, with the navel most likely acting as the port of infection. Unfavorable environmental conditions affect the closure of the navel and thus expose the ducklings to infections. All the bacteria found in eiders in this study belong to the normal microbiome of the birds' skin or digestive tract. The causes of death of adult eiders were the so-called usual, as they largely consisted of individual cases, and no single explanatory factor was found. The result corresponds to the hypothesis presented for the study. Contrary to expectations, the Polymorphus minutus acanthocephalan was not found in PCR studies. However, the study showed for the first time the Profilicollis sp. acanthocephalan in Finnish common eiders. The results are presented in English in Appendix 1.