Untersuchungen zur Endo- und Ektoparasitenfauna freilebender Robbenarten (Carnivora: Pinnipedia) mittels nicht-invasiver Methodik
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Beschreibung
To date, the vast majority of studies on the parasite fauna of pinniped species are based on parasitological necropsies of stranded and/or killed animals, as well as on examinations of captured, restrained or immobilized animals. Especially in the world of today, the life of marine mammals is affected by anthropogenic influences in strong ways and therefore, the use of non-invasive techniques becomes a more and more decisive role to examine wildlife in unmolested manner.
On one side, the aim of the present work was to extend the scientific knowledge on the endo- and ectoparasite fauna of free-ranging South American sea lions (Otaria flavescens) in Chile exclusively using non-invasive techniques. Thereby, a synanthropic colony of South American sea lions was studied in the Chilean city Valdivia – a unique colony, which lives in a freshwater habitat in close proximity to human population and a broad spectrum of domestic and wild animal species. In total, 115 O. flavescens individual faecal samples were sampled within the city of Valdivia and additionally, 79 faecal samples were taken in two free-ranging O. flavescens colonies at the Pacific coast. Overall, using coproscopical techniques nine endoparasite taxa were obtained, including two protozoans (Cryptosporidium spp. and Giardia spp.) and seven metazoan taxa (Anisakidae gen. spp., Diphyllobothriidae gen. spp., Ogmogaster heptalineatus, Trematoda indet. type 1, Trematoda indet. type 2, Otostrongylus circumlitus, Parafilaroides spp.). Thereby, four of these taxa were reported to bear zoonotic potential (Cryptosporidium spp., Giardia spp., Anisakidae gen. spp., Diphyllobothriidae gen. spp.). Helminths of the families Anisakidae (28.7%) and Diphyllobothriidae (16.5%) constituted the most common endoparasites detected in the urban sea lion colony. Sieving of faeces allowed detection of adult helminths and based on morphological and molecular identification various zoonotic species could be revealed: Anisakis simplex/A. pegreffi, Contracaecum ogmorhini, Pseudoterranova cattani und Adenocephalus pacificus. The results of this study revealed also the presence of zoonotic enteric protozoan genera (Cryptosporidium and Giardia) in South American sea lion colonies living in cliffs at the Pacific coast apart from human settlements for first time.
To illustrate interspecific interactions between synanthropic O. flavescens and human population and different animal species, observation and photographical documentation of behavioral manners was conducted over a time period of two and a half months. Based on these observations, a risk analysis on different potential transmission pathways of zoonotic pathogens occurring within the city of Valdivia was conducted.
Sucking lice (Anoplura) of the family Echinophthiriidae are exclusively parasitizing semiaquatic mammals, including various pinniped species and the North American river otter (Lontra canadensis). Due to a lack of adequate sampling techniques to collect echinophthiriid lice without restraining or immobilizing pinniped host species, another aim of the study was to develop and apply a new non-invasive technique within the “urban” South American sea lion colony. Using a lice comb fixed on a telescopic rod, different stages of the echinophthiriid species Antarctophthirus microchir were detected in 4 out of 5 (80%) South American sea lions. Thereby, our results represented the first identification of A. microchir within the urban sea lion colony of Valdivia, and simultaneously, constituted the first report of this parasite fulfilling its complete life cycle in a sea lion colony exclusively composed of male individuals and in a freshwater habitat. The development of this novel method constituted not only a suitable technique for sampling ectoparasites, but also enabled sampling of additional biological epidermic material, e. g. hair, dandruffs, for a wide range of possible studies in the field of marine wildlife parasitology.
Representing haematophagous ectoparasites, echinophthriid species have been suspected to function as vectors for different pathogens, for example as intermediate host of the seal heartworm Acanthocheilonema spirocauda. However, studies on the vector function of these ectoparasites are extremely rare. To extend the current knowledge, more than 1200 seal lice (Echinophthirius horridus) sampled from harbour seals (Phoca vitulina) and one grey seal (Halichoerus grypus) at the Sealcentre Pieterburen (Netherlands) were molecularly screened for the presence of different pathogens. Overall, A. spirocauda-DNA could be proved in seal lice from 35% of examined harbour seals (19/54) and from one grey seal. Furthermore, Anaplasma phagocytophilum and Mycoplasma sp. could be detected in a representative of the family Echinophthiriidae for first time. Our results were indicative that E. horridus functions as intermediate host of A. spirocauda and extended the knowledge on pathogen fauna in echinophthiriid lice.
Autor*in
David Ebmer
Themen in »Untersuchungen zur Endo- und Ektoparasitenfauna freilebender Robbenarten (Carnivora: Pinnipedia) mittels nicht-invasiver Methodik«
Acanthocephala Cestoda Helminthen Kegelrobbe Meer Nematoda Ozean Parasiten Protozoa Robbe Seehund Trematoda freilebende