Bivalve mollusks face a crisis due to infectious diseases, resulting in high mortality and economic losses. The need for continuous monitoring to prevent contamination from sewage and rainwater in aquaculture is evident. The recent mass mortality of scallops in Ilha Grande Bay (IGB), Rio de Janeiro’s largest scallop producer, due to environmental contaminants underscores the need for further research. This study aims to investigate the recent collapse of the scallop population and assess the human impact by analyzing the circulation of pathogens. Materials and Methods: Mollusks were collected from three sites in Ilha Grande Bay (IGB), a region known for its significant scallop production, and from scallop farms in Angra dos Reis, RJ. A total of 216 gill and adductor tissue samples from lion’s foot scallops were analyzed. Bacterial contamination was identified using MALDI-TOF, while antimicrobial susceptibility and carbapenem production were assessed via disk diffusion tests. Results: Mollusks were contaminated with V. alginolyticus, V. fluvialis, V. harveyi, Pseudomonas putida, and Pseudomonas monteilii. All isolates were sensitive to meropenem, but P. putida showed higher resistance to ciprofloxacin. Conclusions: The presence of these pathogenic and resistant bacteria in scallop adductor tissues is a concern for the aquaculture industry and a significant public health risk. The potential for these bacteria to enter the human food chain through consuming contaminated seafood or recreational activities such as bathing is a serious issue that needs to be addressed.

Para el presente estudio, fueron adquiridos 276 atunes, entre enero de 2000 y diciembre de 2002, en mercados de peces, siendo 107 ejemplares de Katsuwonus pelamis (Linnaeus, 1758), 5 Auxis thazard (Lacepède, 1800), 92 Thunnus albacares (Bonnaterre, 1788), 30 Thunnus atlanticus (Lesson, 1830), 25 Thunnus obesus (Lowe, 1839), y 17 Thunnus thynnus (Linnaeus, 1758) pescados en el municipio de Cabo Frio, Estado de Rio de Janeiro, Brasil. Cincuenta y seis (20,28%) de los peces fueron parasitados por lo menos con una especie de parásito. Se colectaron un total de 196 nemátodos larvarios y fueron identificados como: Anisakis (Rudolphi, 1809, det. Krabbe, 1878), A. physeteris Baylis 1923, Contracaecum sp. y Raphidascaris sp. Este estudio es el primer registro en Brasil con nuevos registros para los hospederos de A. simplex en T. albacares, T. atlanticus y T. obesus, de A. physeteris en T. albacares, de Contracaecum sp. en T. atlanticus y T. obesus y de Raphidascaris sp. en T. albacares y T. obesus. Se presentaron sus índices parasitarios de prevalencia, intensidad/intensidad media, abundancia/abundancia media y el rango de la variación de la infección. Los nemátodos se colectaron en la mayoría de los cinco sitios de infección, estómago, intestino, ciego, hígado y cavidad abdominal. A. simplex parasitando T. obesus presentó el mayor nivel de prevalencia (32%), intensidad media (4,6) y abundancia media (1,48); y K. pelamis presentó el mayor rango de la variación de la infección (1-17 parásitos por pez) y el número de sitios de infección (estómago, intestino, ciego, hígado y cavidad abdominal). Se evaluó la importancia de la presencia de larvas de nematodos en estos peces para la salud pública.

This paper presents a novel study on the microbial diversity of Nodipecten nodosus in aquaculture waters and its production. The Lion’s paw scallop (Nodipecten nodosus) is the most economically relevant organism, highly farmed in southeastern Brazil. However, the microbiological contamination of these animals can make their consumption unfeasible. This study assessed the bacterial diversity of Lion’s paw scallop gill arch tissues and the surrounding water of a scallop farm in Angra dos Reis, Rio de Janeiro, Brazil. The isolates (n = 216) were submitted to MALDI-TOF MS identification. Susceptibility to antimicrobials and the ability to produce carbapenems were analyzed by disk diffusion. Studies with isolates of Pseudomonas putida exhibited the highest percentage of resistance to ciprofloxin (42%). All Pseudomonas putida isolates were sensitive to meropenem. Vibrio alginolyticos and Vibrio fluvialis exhibited greater resistance to meropenem. The presence of resistant Vibrio spp. and Pseudomonas spp. and potentially pathogenic bacteria in the analyzed waters and gill arch tissues highlights potential antimicrobial resistance reservoirs, suggesting public health risks regarding bathing in the waters and consuming Lion's paw scallops from the analyzed farm.