Morphometry and morphology of fish otoliths on the coast of the state of Maranhão, Brazil.

The main objective of this study was to evaluate the biometric relationships between the species Bagre bagre, Lutjanus synagris and Nebris microps and their otoliths. The relationship between the size of the otolith (length and weight) and the size of the fish (standard length and total weight) was determined using the linear regression model (y = a + bx). For the morphological description, the otoliths of three specimens were selected by standard length class (10mm). The morphological characters analyzed were chosen according to traditional literature. Three hundred eight specimens of B. bagre, 200 of L. synagris and 237 of N. microps were analyzed. Throughout the collection period, the source of the capture of individuals was the municipality of Raposa. The linear correlations for fish and otolith length for B. bagre were 0.9129 and 0.9652, respectively. For L. synagris, the coefficients were 0.8634 and 0.8672, while for N. microps, 0.9597 and 0.8636, respectively. The morphological classification of L. synagris and N. microps is of the Saggita type, and the B. bagre species is of the Lapillus type. From the data presented here, it is possible to observe that otolith morphometric and morphological data can serve as a parameter to estimate the relationship between the fish and the otolith in terms of its biomass and the length of an individual and a population.

Biomarcadores histológicos em brânquias de Sciades herzbergii (Siluriformes, Ariidae) capturados no Complexo Estuarino de São Marcos, Maranhão / Histological biomarkers in gills of Sciades herzbergii (Siluriformes, Ariidae) caught in the Estuarine Complex of São Marcos, Maranhão

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.(AU)

This study aimed to compare an environmental quality of two areas of the estuarine complex of São Marcos using gills of changes in Sciades herzbergii as biomarkers of aquatic contamination. Samples were made during the dry season (September/ December 2015) and rainy season (March/ June 2016). They were captured 40 specimens of S. herzbergii at two different points of the estuarine complex: A1) Itaqui port (potentially contaminated area); A2) Igarapé do Puca, Alcântara (control area). Abiotic variables were recorded: salinity, temperature, pH and dissolved oxygen. In the laboratory, the gills of each species were fixed in 10% formaldehyde and kept in 70% alcohol until the usual histological technique was performed. The gill alterations identified in the fish of the potentially contaminated area were: epithelial displacement (DE), congestion (CO), aneurysm (AN), lamellar fusion (FL), hyperplasia (HI), capillary dilation (DC), necrosis and epithelial cell proliferation (PCE). The changes in the control region were: epithelial displacement (DE), lamellar fusion (FL), necrosis (NE) and epithelial cell proliferation (PCE). Gill alterations were more frequent in the port region (84%) than in the control region (16%). These results indicate that fish from the potentially contaminated area are presenting biological responses to local stress.(AU)