A Simple Mathematical Model Based on Biomarkers in Stress-Resistant Catfish Species, Sciades herzbergii (Pisces, Ariidae), in São Marcos Bay, Brazil

Investigating spatial-temporal contamination for two environments of the Amazon estuary: A multivariate approach

An assessment of environmental quality in Amazonian estuaries utilizing histological and immunohistochemical biomarkers concomitantly with analyses of trace metals in the tissues of Sciades herzbergii, also considering physical chemical analyzes of the water. 352 animals were captured from two sites and during two periods (dry and rainy). Site 1: São Marcos Bay - heavy anthropic influence and Site 2: Caeté estuary-preserved estuary. In the laboratory, the fish were weighed (g) and measured (cm). Fragments of gills and liver were analyzed using histology and immunohistochemistry (Caspase 3). The specimens from Site 1 presented a low-value condition factor, with the highest concentrations of Al, Cd, and Hg appearing in the muscle, and most severe damages to gills and liver. In contrast, individuals from Site 2 presented a high-value condition factor and showed low metal concentrations in the muscle with only slight tissue lesions. Furthermore, our results demonstrated that seasonal changes affect metal modulation and pathologies in fish at Site 1. The sentinel species chosen in this study is considered a strong bioindicator of pollution and the combination of different biomarkers was efficient in providing a clear view of the signs of exposure to pollutants, and the risks posed to fish health by the presence of metals in the environment, especially in Site 1.

DNA damage in an estuarine fish inhabiting the vicinity of a major Brazilian port

The Itaqui Port Complex (northeastern Brazil) is one of the largest Brazilian port facilities, whose effluents and waste are dumped directly into the estuarine waters. Although environmental monitoring has been a concern around this site, there has been no toxicogenetics study on organisms living in this environment. Thus, we assessed the toxicogenetics potential of the estuarine waters surrounding Itaqui, using the native catfish Sciades herzbergii as a biomonitor. We found a significantly higher frequency of genetic damage and mutations in the animals collected near to Itaqui in both seasons compared to the reference site (distant from Itaqui with no port activities). We also quantified chemical elements in the surface water and sediments near the port and found that clorine, phosphorus, zinc, and boron were above the limits set by the Brazilian legislation. We suggest that such contaminants are involved in the origin of DNA damage. Moreover, we recommend including toxicogenetics assays in the environmental monitoring of pollutants, as well as in the definition of their allowable limits, as they could be used as law enforcement tools and help to predict large-scale contamination events associated with port activities.

Sediment contaminant levels and multibiomarker approach to assess the health of catfish Sciades herzbergii in a harbor from the northern Brazilian Amazon

The current study combined chemical data on trace elements and polycyclic aromatic hydrocarbons (PAH) from sediment and used a multibiomarker approach in the catfish Sciades herzbergii to evaluate two different sites in São Marcos Bay, Brazil. Higher diffuse contaminations by trace elements and PAH were detected in the sediment of Porto Grande (PG) harbor than in the Ilha dos Caranguejos (IC) reference area. A multibiomarker was used in catfish to evaluate the bioavailability of PAH in bile and the effects of pollutants in target tissues. The parameters considered were oxidative stress biomarkers (SOD, CAT, GSH, GST and LPO) and histopathological alterations and were compared between two seasons. The biological responses revealed adverse effects on the population, as indicated by the presence of trace elements and PAH as stressors. Principal component analysis (PCA) of the biomarkers corroborated these results and indicated that fish from the PG site during the rainy season in 2019 exhibited many biological effects compared to 2018. Overall, the present study showed that environmental contamination increased over the years and provides information on the contamination of sediments in the São Marcos Bay, Brazil. The results showed that the presence of contaminants was correlated with the health status of the catfish S. herzbergii.

Biomarcadores histológicos em brânquias de Sciades herzbergii (Siluriformes, Ariidae) capturados no Complexo Estuarino de São Marcos, Maranhão

RESUMO Neste estudo, objetivou-se avaliar a qualidade ambiental de duas áreas do complexo estuarino de São Marcos, utilizando-se as alterações branquiais em Sciades herzbergii como biomarcadores de contaminação aquática. Foram realizadas coletas no período de estiagem (setembro/dezembro de 2015) e no período chuvoso (março/junho de 2016). Foram capturados 40 exemplares de S. herzbergii em dois locais distintos do complexo estuarino: A1) Porto do Itaqui Bacanga (área potencialmente impactada); A2) Igarapé do Puca, Alcântara (área controle). Foram registradas as variáveis abióticas: salinidade, temperatura, pH e oxigênio dissolvido. No laboratório, as brânquias de cada espécime foram fixadas em formol a 10% e mantidas em álcool a 70% até a execução da técnica histológica usual. As alterações branquiais identificadas nos peixes da área potencialmente contaminada foram: deslocamento do epitélio (DE), congestão (CO), aneurisma (AN), fusão lamelar (FL), hiperplasia (HI), dilatação capilar (DC), necrose (NE) e proliferação de células epiteliais (PCE). As alterações na região controle foram: deslocamento do epitélio (DE), fusão lamelar (FL), necrose (NE) e proliferação de células epiteliais (PCE). As alterações branquiais foram mais frequentes na região portuária (84%) do que na região controle (16%). Esses resultados indicam que os peixes da área potencialmente contaminada estão apresentando respostas biológicas ao estresse local.

Changes in Glutathione S-Transferase Activity and Parental Care Patterns in a Catfish (Pisces, Ariidae) as a Biomarker of Anthropogenic Impact in a Brazilian Harbor

Catfish have been used as a model system for studying biochemical mechanisms of biotransformation. The main goal of this study was to identify alterations in hepatic glutathione S-transferase (GST) activity and changes in the parental care pattern of a mouth-brooding catfish, Sciades herzbergii, as a biomarker of anthropogenic impact in a port area on the northeastern coast of Brazil. The fish were sampled from a natural reserve (A1 = reference site) and from an industrialized port area (A2 = impacted site). Two analyses were carried out: hepatic GST activity and mouth-brooding behavior of males. Catfish collected from the A1 site displayed all stages of gonadal maturation, and some of the adult males were mouth brooding 12-30 embryos. Not all gonadal maturation stages of the catfish were represented at the A2 site, and no mouth-brooding males were observed. GST activity in the liver of S. herzbergii was significantly higher in fish from the impacted site compared with fish from the reference site. Values for the enzymatic activity increased progressively in fish sampled from the reserve area as they became more reproductively mature (immature ≤ maturing ≤ mature ≤ spent). However, the greatest values for GST activity (2.84 ± 0.31 μmol min^-1 mg protein^-1) among fish sampled from the impacted area were found in (immature) juveniles. These data suggest that changes in hepatic GST activity and mouth-brooding behavior of S. herzbergii can be used as biomarkers of anthropogenic impact.

Genotoxic and hematological parameters in Colossoma macropomum (Pisces, Serrasalmidae) as biomarkers for environmental impact assessment in a protected area in northeastern Brazil

Genotoxic and hematological parameters in tambaqui (Colossoma macropomum), a native freshwater fish, were used as biomarkers to assess exposure to environmental stressors within the Maracanã Protected Area of Maranhão State, Brazil. Fish were sampled at two sites-Serena Lagoon (control) and Ambude River-on four occasions (dry and rainy season), and biometric data (length and weight) recorded and blood collected from all fish for analysis. Erythrocyte indices-mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration-were calculated. Blood samples were stained with Giemsa and acridine orange, and microscopically examined for micronuclei and morphological nuclear abnormalities. Micronuclei were observed in fish from both sites, although the frequency was significantly higher in fish from the Ambude River and morphological nuclear abnormalities were only observed in fish from the Ambude River. More morphological nuclear abnormalities and a larger number of micronuclei were observed in erythrocytes stained with acridine orange compared with those stained with Giemsa. On average, erythrocyte indices were lower in fish from the Ambude River than from the Serena Lagoon. The results confirm that genotoxic and hematological parameters in C. macropomum can be used as indicators of environmental health and could be valuable tools for monitoring environmental conditions within protected areas.