In vivo exposure to high temperature compromises quality of the sperm in Colossoma macropomum.

Increases in temperature can affect the reproduction of fish by decreasing the quality of gametes for fertilization. Therefore, this study aimed to evaluate the in vivo effect of temperature on the production and sperm quality of Colossoma macropomum, which is an economically relevant species for Brazil, and other countries. Broodstock were exposed for 10 days at temperatures of 29 °C (n = 4) and 35 °C (n = 4). After exposure, semen was collected and sperm quality was evaluated for kinetic, biochemical, morphological parameters, membrane integrity, and oxygen consumption. The sperm quality of males of specimens of C. macropomum exposed in vivo to the higher temperature was compromised and showed a difference in all the analyses (P < 0.05). Sperm showed decreased motility (51.9 ± 11.6 s) compared to the control (61.3 ± 5.5 s); curvilinear (CLV), straight line (SLV), and average path (APV) velocities decreased, and straightness (STR) and beat cross frequency (BCF) increased; oxygen consumption decreased (32.8 ± 3.4 pmol. (s.ml)-1, picomol per second per ml) compared to the control (46.6 ± 3.5 pmol. (s.ml)-1); and the activity of catalase (CAT) and glutathione S-transferase (GST) enzymes increased and decreased, respectively, in sperm from fish exposed to high temperatures. Furthermore, an increase in non-viable sperm with damaged membranes and sperm with altered morphology was observed. The observed alterations indicate that C. macropomum confined in environments with high temperatures possibly produces more sperm that are unviable for the fertilization process.

Biochemical and Histological Biomarkers in Crassostrea sp. (Bivalvia, Ostreidae) for Environmental Monitoring of a Neotropical Estuarine Area (São José Bay, Northeastern Brazil).

This study aimed to compare biochemical and histological biomarkers in oysters to identify impacted areas in a Brazilian port region. Oysters belonging to the Crassostrea genus were collected in two points in São José Bay (Brazil): (A1) Curupu Island (control area) and (A2) Braga Port (impacted area). Digestive glands from oysters were used to analyze the enzymatic activity of glutathione S-transferase and Catalase. The gills were used for standard histology analyses. Water samples were collected for metal analyses. Our results indicated that there was a change in the activity of oyster GST and CAT enzymes, especially in A2. Histological gill analysis indicated more frequent changes in A2. The analyzed metals presented higher values in A2. The results of this study suggest that enzymatic alterations, histological changes and higher metal values are indicative of initial stress caused by contaminants in São José Bay, especially in the port region.

Copper and cadmium impair sperm performance, fertilization and hatching of oocytes from Amazonian fish Colossoma macropomum.

The contamination of aquatic environments by transition metals can have a direct influence on the reproductive process of several organisms in the aquatic biota. This study aimed to evaluate the effect of cadmium and copper on the sperm of tambaqui (Colossoma macropomum). Male (n = 4) and female (n = 4) specimens of C. macropomum were induced to spermiation and ovulation, with sperm being activated in the following media: 0; 0.6; 1.2 and 1.8 mg/L of cadmium (CdCl2) and 0; 0.4; 0.8 and 1.2 mg/L of copper (CuCl2). Sperm quality was assessed through time (s) and motility rate (%), superoxide dismutase (SOD) and glutathione S-transferase (GST) activities, lipoperoxidation levels (LPO), and morphological characteristics. In parallel, the effects of these metals on the rate of fertilization and hatching of the oocytes were evaluated. The duration and motility rate of sperm were longer in the control treatment, 85.67 ± 11.01 s; 90 ± 0.01%, and progressively decreased to 44.67 ± 4.16 s and 60 ± 5%, respectively, in concentrations of 1.8 mg/L (44.67 ± 4.16 s; 60 ± 5%) of CdCl2 and to 65.67 ± 3.30 s; 70 ± 5%, respectively, in concentrations of 0.8 mg/L of CuCl2. We observed an increase in the activity of the SOD enzyme in sperm cells exposed to 1.2 mg/L of CdCl2. The LPO levels were increased significantly in sperm cells exposed to 1.2 and 1.8 mg/L of CdCl2 and 0.8 mg/L of CuCl2. Fertilization and hatching were severely impaired in the presence of Cd and Cu. These data indicate that environments contaminated with cadmium and copper harm the gametes of C. macropomum.

Histological Changes in the Kidney of Sciades Herzbergii (Siluriformes, Ariidae) for Environmental Monitoring of a Neotropical Estuarine Area (São Marcos Bay, Northeastern Brazil).

The aim of this study was to evaluate the environmental quality of a port in Brazil using the renal alterations in Sciades herzbergii as biomarkers of aquatic contamination. Samples of S. herzbergii were collected in two areas in São Marcos Bay, Brazil: (A1) Itaqui Port (potentially impacted area); and (A2) Puca Creek (control area). At the same time, the abiotic data was obtained, in addition to the sampling of water for metals analysis. The fish kidney of each specimen was submitted to the usual histological technique. It was possible to identify alterations such as melanomacrotic centers, dilation of the glomeruli, capillary endothelium gap, occlusion of the tubular lumen, immature nephron and dilated vessels. Samples of S. herzbergii collected in the port region showed a higher frequency of renal alterations, indicating that the organisms present in that region are probably suffering due to the impacts caused by the port activities.