ESTRUCTURA POBLACIONAL PARASITARIA Y FACTOR DE CONDICIÓN DE PSALIDODON RUTILUS EN UNA RESERVA DE LA REGIÓN PAMPEANA ARGENTINA.

YASMIN CROCI; MACARENA DE MARTINO; JORGE BARNECHE; SERGIO R. MARTORELLI; MARTIN MIGUEL MONTES

Conferencia; XI Congreso Internacional de Parasitología Neotropical; 2023

The Juan Blanco stream dissipates into a wetland at the end of its course within the coastal plain of the Río de la Plata. It has a basin of 115 km2, which has mostly extensive livestock farming with 14% of its surface area under cultivation. It also belongs to a series of streams in the Parque Costero del Sur Biosphere Reserve that have not been properly studied in terms of interaction, composition and ichthyofaunal exchanges and the influence of the Río de la Plata. Psalidodon rutilus is one of the most represented species (22%).It inhabits calm waters of streams and rivers where it has an omnivorous and voracious diet based mainly on fish, insects, and microcrustaceans. P. rutilus is widely used as bait by fishermen due to its numerous populations in lentic environments in Buenos Aires. Additionally, owing to its conspicuous coloration, it is utilized by aquarists. Previous work has only focused on fish, but none of them have studied the parasitic composition. The aim of this study is to analyze the metazoan parasite populations of P. rutilus within a protected area. A total of 50 specimens were collected in winter 2019. After capture fish were kept alive in plastic bags containing water from the stream with added oxygen and transported to the laboratory. Immediately upon arrival they were euthanized, sexed and measured for standard length, total length and weighed. Fish were examined for helminths under a binocular stereo-microscope. Parasites were observed in vivo, counted, killed in hot water and preserved in 90% alcohol or fixed and preserved in 10% formalin. All parasites were identified to the lowest possible taxonomic level. The Fulton’s condition index (K) was calculated for each fish. We found five parasite taxa represented by: larvae of Heterophyidae in gill filaments (Ascocotyle sp.1), muscles (Ascocotyle sp.2) larvae of Anisakidae (Contracaecum sp) in body cavity, adults of Haploporidae (Saccocoelioides sp) in the digestive trac and adults of Lernaeidae (Lernaea cyprinacea) in muscles. The condition index ranged from 0.74-2.2 in males, and 0.64-1.86 in females. Our study provides further evidence for studies of complex population dynamics including more accurate determination of the taxa under study and mapping of parasitic cycles in a reserve characterized by the diversity of migratory birds.