Biodiversidade de parasitos de peixes de importância econômica comercializados na ilha de São Luís-MA

Abstract

The aquatic environment has been suffering successive anthropogenic interference, leading to changes in the environment that directly impact the diversity of species of both parasites and their hosts. In this context, helminths present themselves as significant components within biological systems, being important agents that regulate the abundance and distribution of species and host populations. This investigation aimed to characterize the parasitic fauna associated with the main species of fish of economic importance sold on the island of São Luís – MA, through morphological characterization studies and analysis of parasitological descriptors for the different species of helminths found. The hosts were obtained at the fish market, at the Cidade Operária fair and directly from artisanal fishermen in Laguna da Jansen on São Luís Island, and in a fish, farm located in the municipality of Matinha, state of Maranhão. Soon after acquisition, the fish were placed in thermal boxes and transported to the <Laboratório do Núcleo de estudos Morfofisiológicos Avançados - NEMO, Universidade Estadual do Maranhão (UEMA)=, where identification, biometry, necropsy, and parasite collection were carried out. 236 hosts were acquired and analyzed, belonging to 35 different species distributed among the orders Elopiformes, Perciformes, Mugiliformes, Siluriformes, Batrachoidiformes and Characiformes. The gills were removed and placed in flasks containing hot water (c. 65°C) and then shaken vigorously to detach the parasites from the gill filaments. Soon after, absolute ethanol was added until reaching a concentration of approximately 70%, followed by fixation. To study endoparasites, the internal organs were individualized and opened with finetipped scissors and placed in containers filled with 70% ethanol. These vials were sent to the "Laboratório de Helmintos Parasitos de Peixes, Instituto Oswaldo Cruz, FIOCRUZ", where the helminths were collected and identified. The parasites were processed according to a specific methodology for each group. Some monogenoid specimens were mounted in Hoyer's medium to study the sclerotized parts; others were stained with Gomori trichrome to study internal organs. Nematodes were cleared with lactophenol or glycerin for examination under a light microscope. Cestoda and Digenea were stained with Langeron's alcoholic carmine, dehydrated in an ethanol series, clarified in clove oil, and mounted in Canada balsam. Of the total fish examined, 229 were parasitized by at least one species of parasite, with a total of 2,221 helminths being collected, of which 1,924 Monogenoidea belonging to the à Ameloblastella formatrium, Anacanthorus simpliciphallus, Chauhanellus hamatopeduncularoideum, Chauhanellus neotropicalis, C. susamlimae, Cosmetocleithrum akuanduba, C. bifurcum, C. brachylecis, C. leandroi, C. ludovicense, C. undulatum, C. gussevi, Diplectanocotyla megalops, Hamatopeduncularia bagre, H. cangatae, Metacamopia oligoplites, Mymarothecium sp., Probursata brasiliensis, Pseudomazocraes sulamericana, P. seleni, Pseudorhabdosynochus americanos, Rhabdosynochus hudsoni, R. rhabdosynochus, Rhamnocercus microps; 67 Digenea: Brachyphallus parvus, Brachyphallus sp., Manteria brachyderus, Prosorhynchus sp., Stephanostomum sp., Torticaecum (Didymozoidae), Tubulovesicula lindberghi; 4 Aspidogastrea: Lobatostoma ringens; 23 Cestoda: Callitetrarhynchus gracilis and 203 Nematoda: Anisakidae gen. sp., Ascarophis sp., Capillaridae gen sp., Contracaecum sp., Cucullanus sp., Hysterothylacium fortalezae, Hysterothylacium sp. e Raphidascaris sp. In the present study, a list of all helminths found is presented, including host and type locality, previous records in South America, references and new records of hosts and geographic distribution