Acute and subchronic effects of ibuprofen on the ten spotted live-bearer fish Cnesterodon decemmaculatus (Jenyns, 1842).

Ibuprofen (IBP) is an anti-inflammatory drug found in aquatic environments, potentially toxic for the biota. We exposed the test fish C. decemmaculatus to two environmentally relevant concentrations (50 and 100 µg IBP/L) for 4 and 12 d and evaluated the effect on some biomarkers. Micronucleus test, nuclear abnormality test and comet assay indicated cyto-genotoxicity at both concentrations and exposure periods. Oxidative stress and biochemical biomarkers were not affected, excepting muscle AChE activity for 4 d. Muscle metabolic biomarkers showed significant decrease in ETS, lipid and protein content, while carbohydrate content was not affected. The CEA index increased at the lower IBP concentration for 4 and 12 d, possibly due to changes in body energy reserves. A full-factorial GLM performed to assess the effects of IBP and exposure times showed that the metabolic and genotoxicity biomarkers were the most sensitive to IBP toxicity, mainly at 50 µg IBP/L for 4 d.

Impact of exposure to arsenic on the bacterial microbiota associated with river biofilms in the Pampas region.

Freshwater contamination by arsenic (As) is a worldwide problem. It may be found in Pampean streams of Argentina at concentrations higher than those recommended by international organizations and stipulated by national regulations. Exposure to high As concentrations causes serious consequences to both human health and the environment. The general objective of this work was to evaluate the effect of As on the biofilm microbiota structure from Naveira stream, Luján, Province of Buenos Aires (Coordinates: 34º34'02″ S 59º03'51″ W). The biofilm collected was cultivated in glass aquaria at different As III concentrations (0, 0.2 and 20 mg / L), inside incubation chambers under controlled conditions (16 h light: 8 h dark and 24 ± 1 °C) and constant aeration for 31 d, with partial water renewal every 9 d. We amplified the hypervariable regions V3 and V4 of the bacterial 16S rRNA gene from biofilm bacterial community samples to determine the diversity and abundance of the different taxa. The taxonomic composition of each sample, the alpha diversity of each treatment and the main metabolic pathways were analyzed. Principal Component Analysis of the present phyla and a Linear Discriminant Analysis of the metabolic pathways was also performed. Significant changes were observed in relation to the taxonomic composition of the bacterial community after exposure to the metalloid. However, this effect was not observed at the low concentration used (0.2 mg / L), which is the one that corresponds to ecologically relevant levels. The significantly affected phyla were Verrucomicrobiota, Acidobacteriota, Patescibacteria, Hydrogenedentes and WPS-2. The relative abundances of the Verrucomicrobiota, WPS-2 and Patescibacteria groups were notably decreased in the treatment with high As, while the Acidobacteria group was increased in both treatments with As. The stream samples showed greater bacterial diversity than those grown in the laboratory without As. Finally, it was possible to characterize the metabolic profile of the biofilm developed under natural conditions in the leaves of the aquatic plant Elodea canadensis in the Naveira stream. In addition, results showed that biosynthesis-related pathways were more abundant at the high As concentration treatment (20 mg / L).

Occurrence and accumulation of pharmaceutical products in water and biota of urban lowland rivers.

We evaluated the distribution of eleven groups of pharmaceutically active compounds (PhACs) in surface waters and biota of different trophic levels, in five sites of two lowland urban rivers in Argentine. Twenty-nine out of 39 PhACs and two metabolites were detected in at least one water sample (2-9622 ng/L), eleven detected in biofilms (1-179 ng/g d.w.) and eight in the macrophyte Lemna gibba (4-112 ng/g d.w). The two more polluted sites had a similar distribution of the main groups of compounds. In surface waters, the largest concentrations were for the analgesic acetaminophen (9622 ng/L), the antibiotic sulfamethoxazole (326 ng/L), the antihypertensive valsartan (963 ng/L), the ß-blocking agent atenolol (427 ng/L), the diuretic hydrochlorothiazide (445 ng/L) and the psychiatric drug carbamazepine (99 ng/L). The antibiotic ciprofloxacin exhibited the highest concentration in the biofilm (179 ng/g d.w.) and in the macrophyte L. gibba (112 ng/g d.w.) Several compounds were detected in the water but not in the biota (e.g., codeine and bezafibrate), and others (e.g., azithromycin and citalopram) were found in the biota but not in the surface water. Significant bioaccumulation factors (>1000 L/kg d.w.) were obtained for venlafaxine and ciprofloxacin in biofilm. Our results show that PhACs may accumulate in several biological compartments. Within an environmental compartment, similar PhACs profile and concentrations were found in different sites receiving urban pollution. Among different compartments, biofilms may be the most suitable biota matrix to monitor the immediate reception of PhACs in the biota. Our results indicate that the presence of PhACs in urban rivers and their accumulation in the biota could be incorporated as symptoms of the urban stream syndrome.

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 river's 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.

Use of Lithobates catesbeianus tadpoles in a multiple biomarker approach for the assessment of water quality of the Reconquista River (Argentina).

The water quality of the Reconquista River (Argentina) water was monitored between 2009 and 2010 by means of a multiparametric approach. This periurban river is affected by agricultural, urban, and industrial discharges. Water samples were collected at a dam located in the headwaters and at 18 km downstream (M). Physicochemical profile and two water-quality indices (WQIs) were determined. Laboratory bioassays were performed by exposing Lithobates catesbeianus tadpoles to environmental samples for 96 h and determining the following parameters: (1) brain: acetylcholinesterase (AChE) activity; (2) gill: catalase and glutathione-S-transferase (GST) activities and glutathione (GSH) content; (3) liver: CAT and GST activities, superoxide dismutase, lipid peroxidation, and GSH content; (4) condition factor and hepatosomatic index; and (5) genotoxicity [micronucleus (MN) test in erythrocytes]. Physicochemical profile and WQIs corresponded with extensive pollution in M. Important temporal and spatial variability in biomarkers of tadpoles exposed to samples was found. Multivariate analyses showed that AChE in brain, MN frequency, liver and gill GST activities, and GSH content were key biomarkers.

Quantitative behavioral parameters as toxicity biomarkers: fish responses to waterborne cadmium.

The disruptive sublethal effects of heavy metals on behavioral parameters of fish as biomarkers of aquatic toxicity have been scarcely studied. We investigated the impact of exposure to sublethal waterborne cadmium on locomotory parameters of three freshwater teleosts: Cyprinus carpio as reference species, and Australoheros facetum (sin. Cichlasoma facetum) and Astyanax fasciatus, native to Pampean ecosystems in Argentina, using a noninvasive bioassay under laboratory conditions. Fish were successively transferred to media containing freshwater (control period), Cd(2+) solutions (exposure period), and freshwater (recovery period). The behavioral biomarkers evaluated were swimming activity and swimming speed of fish. The metal provoked different responses of both parameters after 4-7 days of exposure; the reversibility of changes was also assessed. It was concluded that: (a) locomotion parameters are sensitive endpoints and useful biomarkers in behavioral studies of freshwater toxicity, (b) the applied bioassay could be a valuable tool in water quality monitoring, and (c) the studied species differed in their susceptibility to the toxicant as well as in their capacity to return to basal values.