Larval nematodes in stomach wall granulomas of smelt Osmerus eperlanus from the German North Sea coast

Abstract

Occurrence of stomach wall granulomas in European smelt was studled at 6 locations along the German North Sea coast. Identification of larval nematodes inhabiting these granulomas is provided for the first time. Three species, isolated by pepsin-HC1 digestion, are involved: Hysterothylacium cf. cornutum, Cosmocephalus obvelatus and Paracuaria tridentata. 7 2 % of all stomachs examined were affected. The ratio of number of granulomas to number of the 3 larval species free in the mesentery was 1:1.3. Differences in prevalences and intensities were significant among all locations. Granuloma abundance was highest in samples from the Elbe estuary decreasing in the other locations relative to their distance from the Elbe. There was no relationship between the number of larvae encapsulated on the stomach wall and the number of larval P decipjens in the musculature (r = 0.3).

Helminths of European smelt Osmerus eperlanus (Linnaeus, 1758) in Lake Hańcza and the Vistula Lagoon, with special regard to their zoonotic threats

“…Parasitological studies of smelt caught in the estuaries of the Elbe and in the North Sea have shown that the prevalence of P. decipiens often exceeds 40% (Möller and Klatt, 1990;Obiekezie et al, 1992;Karl, 2006;Kuhn et al, 2013). They have usually been found in muscles, where they settle after a fish dies, abandoning the intestinal walls and the body cavity.…”

“…Populations of European smelt in the Baltic and North Seas and in coastal lakes are known to be infected with larvae of Anisakidae nematodes, such as Anisakis simplex, Pseudoterranova decipiens, Contracaecum osculatum, Hysterothylacium aduncum (Möller and Klatt, 1990;Obiekezie et al, 1992;Wiśniewski and Piasecki, 2001;Karl, 2006;Kuhn et al, 2013;Głoćko, 2016). The life cycle of these nematodes is associated with salt water, where the planktonic and benthic crustaceans are the first intermediate host, while whales (for A. simplex) and seals (for P. decipiens and C. osculatum) act as definitive host.…”

Sealworm Pseudoterranova decipiens s.s. infection of European smelt Osmerus eperlanus in German coastal waters: ecological implications

“…The occurrence of nematodes in the European smelt has been extensively investigated (e.g. Möller & Klatt 1990, Obiekezie et al 1992, Karl 2006. However, comparatively few current studies have been conducted regarding both the number and the location of larvae in different areas of the edible muscle parts and the molecular analyses of the parasites.…”