Noever, Christoph (2009) Diet of metazoan parasites of deep-water fishes of the Azores. (Diploma thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 93 pp.

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Abstract

Deep water squaloid sharks of the Azores were analyzed for their feeding ecology and metazoan parasites. A total of 108 specimens belonging to three species oflantem sharks (Genus Etmopterus) were investigated: E. spinax, E. pusillus and E. princeps. The sharks were caught in Azorean waters by longlines in 2008 during fishery surveys or obtained from local fishermen. feeding ecology was investigated by analyzes of stomach contents and complemented by analyzes of stable isotopes of nitrogen and carbon from the muscle tissue. The stomach contents of all three species consisted of the major taxonomic groups Teleostei, Cephalopoda and Crustacea, but the importance of the single groups differed widely between the different shark species. Distinct ranges in the ratios of stable isotopes were achieved for each species, indicating discrete feeding niches among the sharks. Results of the diet analyzes together with a distinct depth prevalence of each shark species in the investigated area indicates little resource competition between the three morphological quite similar species. A total of 29 parasite species were identified, with the majority of them belonging to the Cestoda with 16 species, followed by Crustacea with six species, Nematoda with three species, Monogenea with two species, and each a single species of Acanthocephala and Digenea. A total of 33 new host records were established in this study, including an undescribed species oftrypanorhynch cestode ofthe genus Aporhynchus. Due to the high number of cestodes, endoparasites dominated with 21 species, while seven species were ectoparasitic and one species mesoparasitic. The parasite fauna differed strongly between the three shark species, with only few larval cestodes and nematode species occurring in more than one of the three shark species. Altogether, the results obtained from the diet analyzes, the stable isotopes and parasitological investigations indicate distinct ecological niches between the three investigated shark species. Beside morphological characteristics and genetic analyzes, the investigation of parasite fauna can be used as a tool for the particularly problematic identification of morphological similar species of lanternsharks. Further investigation of the parasite fauna of those sharks from other regions could be used in the differentiation of possible discrete populations. The parasite fauna of E. spinax from the present study already showed large differences to that observed in its northern distribution range. Intense parasitological investigations from other regions on the other two investigated shark species are lacking, thus the potential ofparasitological investigations ofthose species remains great.

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