Invasive Species Compendium

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Abstract

Mortality of juvenile So-Iuy Mullet, Liza haematocheilus (Teleostei, Mugilidae), in the Sea of Azov associated with metacercaria (Digenea).

Abstract

Age-dependent patterns, including yearly variations of digenean metacercariae infestations of the introduced species, Liza haematocheilus (Temminck & Schlegel, 1845), were studied. We evaluated the impacts of three metacercaria species, Timoniella imbutiforme (Molin, 1859) Brooks, 1980, Diplostomum spp. and Ascocotyle (Phagicola) longa Ransom, 1920, on juvenile fish in age from one month to 2+years old from the Molochny Estuary and neighboring waters of the Sea of Azov by applying Crofton's negative binomial truncation technique, epidemiologic and aggregation indices. Parasite surveys executed in 1997-2014 revealed significant yearly differences in the infection dynamics of studied metacercariae in juvenile fish of L. haematocheilus. Metacercariae were absent or fish harboured several times less parasites in 2005-2013 than in 1997-1999. T. imbutiforme infection exhibits a convex that was observed in a decline of the parasite load after an initial increase. The infection load of Diplostomum spp. increased asymptotically with the fish age reaching maximum value in two years old juveniles. Both the abundance and the prevalence of A. (P.) longa were low in juveniles of two month and two years old but relatively high and more or less constant during the rest of the juvenile period. Results of the present study suggest that metacercariae, especially, T. imbutiforme, are associated with mortality of juvenile Liza haematocheilus.