Bettina Lorena Eissa

Short communication: Cadmium bioconcentration and genotoxicity in the common carp (Cyprinus carpio)

Heavy metals in the aquatic environment pose high ecotoxicological risk to fish. Cadmium is one of the most abundant pollutants in freshwater bodies in Argentina. An evaluation was performed of the responses of several exposure biomarkers of juvenile Cyprinus carpio exposed during five days to sublethal cadmium (0.5 mgL−1) and cyclophosphamide (5 mgL−1). The assessment involved evaluating the impact of exposures on the following parameters of fish: Condition Factor (CF), Hepatosomatic Index (HSI), tissue accumulation (brain, muscle, gills, liver and blood) and erythrocyte micronuclei (MN) frequency. Compared with controls CF showed no significant changes and HSI registered a declining tendency. The metal accumulated mainly in the gills and to a lesser proportion in the liver and blood; in the brain and muscles, the quantities determined were no different from those found in the controls. MN frequency in erythrocytes increased significantly among fish exposed both to cadmium and to cyclophosphamide.

Effects of sublethal waterborne cadmium on gills in three teleosteans species: scanning electron microscope study

The effects of acute exposure for 96 h to a sublethal concentration of cadmium (300 µg L−1) on the surface gill morphology of the teleosteans Cyprinus carpio, Australoheros facetum and Astyanax fasciatus were studied using Scanning Electron Microscopy (SEM). The main cadmium-induced gill damages in the three species were: structural alterations, oedema and fusion of adjacent secondary lamellae; there was a remarkable disruption of the gill epithelium in Australoheros facetum and excretion of large amount of mucus on the lamellae in Astyanax fasciatus. The reversibility of the alterations after a depuration period was also investigated; in all cases the fishes exhibited a considerable recovery of the gill structure after 96 h in a cadmium-free medium.

Multibiomarker response in ten spotted live-bearer fish Cnesterodon decemmaculatus (Jenyns, 1842) exposed to Reconquista river water

The aim of this paper is to assess the water quality to chemical pollution at Roggero Dam, the headwater of the Reconquista river, and to perform a Cadmium (Cd) contamination pulse simulation through a wide battery of biomarkers which included: genotoxicity and enzymatic biomarker parameters on a neotropical teleost fish namely Cnesterodon decemmaculatus. Water samples were taken in order to determine the rivers physicochemical profile. An integrative approach was applied using a biomarker index. The bioassay involved the use of laboratory culture adult animals, acclimatized in moderately hard water (MHW) and fed ad libitum. A semi-static 96h bioassay was conducted and the experimental groups were as follows: [1] river water (Rg); [2] river water + 2mg/L Cd (RgCd); [3] MHW + 2mg/L Cadmium (Cd), positive metal control; [4] MHW + 5mg/L Cyclophosphamide (positive genotoxicity control -CP); [5] MWH, negative control (NC). At the end of the exposure time fishes were sectioned and the following biomarkers were determined: 1) condition factor rate (CF); 2) for the anterior section (A) (head): glutathione (GSH) and protein (Pr) content; 3) for the body midsection (M) (viscera): Pr, GSH, Glutathione-S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD). Blood samples were also taken from the fish specimens to estimate the frequency of micronuclei (MN) as well as other nuclear abnormalities (NA). The physicochemical profile of the river water sample indicated high Copper concentrations. CAT and SOD activity and total Pr content did not show any significant changes. GST activity decreased in fish exposed to Rg, while GSH content decreased significantly for all treatments compared to controls in MHW. These results would seem to point to a reduction in cell defense capability as a result of the depletion antioxidants such as GSH. The NA frequency increased significantly in all treated groups while MN frequency was increased only in Cd and CP groups. Using some the biomarkers measured, a biomarker index was estimated which revealed that fish exposed to Rg were 90% affected or highly affected, while those exposed to RgCd were 80% and Cd 68% affected or highly affected. The obtained results indicate the usefulness of the use of a battery of variables by means of the biomarker index to analyze water quality.

Water pollution monitoring of the Lujan River (Argentina): chemical analyses and hepatic biomarkers in Lithobates catesbeianus tadpoles

The toxicological water quality of the Lujan River (Argentina) was monitored during one year seasonal samplings. Water samples were collected at two points and their toxicological profiles were compared: S1 (reference site), located downstream of a major city and S2, located further downstream, beyond a joint urban sewage and industrial discharge point. A number of abiotic parameters were determined and three water quality indices (WQIs) calculated on the samples. Laboratory toxicity bioassays were conducted exposing Lithobates catesbeianus larvae to samples; a third group of animals were exposed to tap water (controls). Hepatic biomarkers were determined: catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD) activities, lipid peroxidation (LPO) and GSH content; CF and HSI were calculated. The scores of the WQIs corresponded to a high pollution condition at both sampling points. ANOVA showed significant differences between sampling sites and controls mainly in CAT activity, GSH content and GST in autumn.

Assessment of physiological effects of sublethal cadmium on Cyprinus carpio

The effects of sublethal and short-term exposure to Cd were assessed with the purpose of studying the energy metabolism parameters in young Cyprinus carpio under laboratory conditions. The fish were exposed to Cd solutions (0.20 mg Cd. L-1) over a two-week term. The assayed concentration was environmentally realistic since it was frequently found in most highly polluted peri-urban water bodies in Argentina. No mortality was recorded among the animals during the experiments. The relationships between assimilation efficiency (U), oxygen consumption as a measure of specific metabolic rate (SMR) and ammonium excretion (AE) were determined. After exposure to Cd, a significant correlation was found between SMR and AE. It was concluded that under the assayed conditions the metal caused alterations in energy-related homeostasis of fish. Most of the responses may be interpreted as indicative of adaptations to compensate for increased energy requirements due to the physiological impairments caused by Cd.