Caracterização morfológica dos metazoários parasitas de serrasalmus rhombeus, “piranha preta” (characiformes: serrasalmidae) oriundos do rio pericumã, no município de Pinheiro, Maranhão, Brasil

Abstract

In the Baixada Maranhense, fish is an essential part of the population's diet, and local communities live off artisanal fishing to generate income and support their families. Among the fish consumed in this region, Serrasalmus rhombeus (Linnaeus, 1766), popularly known as the “black piranha”, belongs to the Serrasalmidae family and the Characiformes order, and is widely distributed in South America. Fish are the group of vertebrates with the greatest predisposition to parasitism, due to intrinsic factors in the aquatic environment, such as: excess carbon dioxide, ammonia and nitrite; low concentration of dissolved oxygen; accumulation of organic matter, as well as the easy dispersal of parasite eggs and larvae in the water, stimulating stress and immunosuppression in the animals' bodies. In the municipalities of Baixada Maranhense, fish is sold in open-air fairs and municipal markets, spaces that generally do not have adequate infrastructure for the sale of food of animal origin, due to poor hygiene conditions, lack of refrigeration and exposure to dust and insects. Fish meat from these municipalities, which have irregular sanitary inspections, can contain parasites embedded in the muscles or lodged in the viscera, affecting the health of consumers, especially when raw or undercooked fish is eaten. Food-borne parasitic diseases represent a major health risk, especially in underdeveloped countries such as Brazil. This study is characterized as descriptive and exploratory, quantitative in nature, with the aim of investigating the parasitofauna of Serrasalmus rhombeus in the Baixada Maranhense region. The sample consisted of 151 specimens of S. rhombeus, collected directly from the Pericumã River (Pinheiro-MA) by local fishermen using gillnets and a motorized canoe. The specimens were collected three times in two seasons, rainy and dry. In the first collection, 50 fish (adults) were obtained, with a total of 100 samples of gills and viscera; in the second, 18 fish (adults) with 36 samples; and in the third, 83 fish (24 adults and 59 juveniles), with 166 samples. All the fish available after fishing were chosen, and none of them had damaged biological material. In this study, Contracaecum sp was the only endoparasite found in S. rhombeus in the rainy and dry seasons, with temporal differences in prevalence and abundance. The average intensity was 6.2 in the rainy season; 7.91 in the 1st collection of the dry season, and 11.64 in the 2nd collection. The average abundance was 3.72 in the rainy season, and 5.2 and 2.38 in the dry season. With regard to parasitism by ectoparasites, monogeneans of the genera Anacanthorus sp, Amphitecium sp and Notozothecium sp were identified, with the species Anacanthorus amazonicus having the highest prevalence. Knowledge of the parasitofauna of S. rhombeus in the Pericumã basin was important for understanding the biological aspects of the host, such as its position in the food chain, as well as the zoonotic potential of the parasites and the conditions of the environment in which they live.