Patricia M. Castañé

Pollution in a Lowland River System. A Case Study: the Reconquista River (Buenos Aires, Argentina)

The Reconquista river is a lowland watercourse; about three million people and several thousands of industries are settled in its flood plain. It can be considered as one of the most polluted rivers of Argentina. The present work is an attempt to describe the quality of the surface water through 16 physicochemical variables measured monthly in five sites (S1to S5) during 1994. Univariate and multivariate analyses of data showed a clear difference of S1and S2respect to S4and S5for ammonium, ortophosphate, pH, hardness, chloride, phenols, BOD, COD, and DO values. S3appears to be a transition site. DO content showed a significant negative regression respect to the distance from the mouth. In the multivariate analyses between seasons the concentration of phenols appeared as an important feature. However it can be considered that seasonal variations were difficult to explain because of the river is the receptor of both regular and intermitent pollution pulses. It was concluded that the deterioration of this water body was progressive downriver, the contribution of the Moron creek in S4determined a sharp adverse change in the physicochemical conditions. In the two downstream sampling stations (S4and S5) the values were far from natural conditions.

Studies on the urinary nitrogen waste products in south american anurans from different habitats

Abstract 1. 1. Urinary nitrogen waste excretion and urea concentration in plasma of juvenile Bufo arenarum and adult Bufo arunco, Bufo fernandezae and Leptodactylus ocellatus were studied; they are terrestrial, cave dweller and semi-aquatic species, respectively. 2. 2. The urinary NH3-N, urea-N and uric acid-N, and plasma urea concentration were measured in samples from animals fasted for 15 days and acclimated at constant temperature over 4 days before sampling. 3. 3. The percentages of urinary urea-N, ammonia-N and uric acid-N were 95.3, 4.3 and 0.12 for Bufo arenarum; 95.0, 5.0 and not determined for B. arunco; 95.3, 4.6 and 0.09 for B. fernandezae; and 91.1, 8.9 and 0.08 for L. ocellatus, respectively. 4. 4. The percentage of urinary nitrogenous compounds was shown to be independent of the habitat and of the body weight of the animals. 5. 5. Plasma urea concentration (in mM) and the U/P ratios were: 19.8 and 1.8 (B. arenarum); 37.9 and 1.6 (B. arunco); 19.3 and 1.8 (B. fernandezae) and 7.6 and 5.2 (L. ocellatus), respectively.

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.

Do Lithobates catesbeianus tadpoles acclimatise to sub-lethal copper?

The aim of this work was to study the acute effects of short-term exposure (96 hours) to sub-lethal concentrations of copper (2 and 3 mg L−1) on ecotoxicological stress biomarkers in the aquatic stages of Lithobates catesbeianus (syn. Rana catesbeiana) larvae. To this end, the effects of copper on brain acetylcholinesterase, liver and gill catalase and glutathione-S-transferase activities were examined. In addition, the changes in gill structure were monitored by scanning electron microscopy. Neither the survival nor the activity of the biomarker enzymes was affected by copper; however, the gills were affected, exhibiting alterations in the epithelial cells of the tufts. The results were interpreted as evidence that, at the concentrations assayed, there may be an acclimation of the tadpoles to copper; the anomalies observed in the epithelium of the gills may be compatible with the survival of the animals since at their developmental stage the skin plays an important role in the respiratory function.

Ontogenic screening of aldosterone in the South American toad Bufo arenarum (hensel)

The content of aldosterone in the South American toad Bufo arenarum embryos developed in Holtfreters 10% solutions and in distilled water was measured. The screening was carried out on embryos from the following periods of their development: 15 min after fertilization; gray crescent-32 cells; mid cleavage-late gastrula; neural plate-neural tube; tail bud-heart beat; gill circulation-tail fin circulation and operculum fold-complete operculum. The aldosterone content of embryos incubated both in Holtfreter and in distilled water decreased gradually up to gill circulation-tail fin circulation stages. The steroid content of both groups of embryos rose sharply at the end of their development (operculum fold-complete operculum); the observed increase was significantly higher in distilled water animals.

Cadmium effects on some energy metabolism variables in Cnesterodon decemmaculatus adults

This work is focused on the responses of some energy metabolism variables in Cnesterodon decemmaculatus adults exposed to cadmium under controlled laboratory conditions. This species has been used as bioindicator for evaluating the effects of different chemicals on diverse biological processes and is frequently used as test organism in ecotoxicity studies that include cadmium as reference toxicant. Animals were exposed for 12 days to the following concentrations: 0, 0.45, and 0.8 mg Cd/L. Food intake, fecal production, specific assimilation, condition factor, mortality percentage, oxygen consumption, oxygen extraction efficiency, specific metabolic rate, ammonia excretion, and ammonia quotient were measured. The overall balance was expressed as scope for growth (SFG). Cadmium-exposed groups showed a significant decrease in food assimilation and condition factor at the end of the exposure. There was an increase in specific metabolic rate and a decrease in SFG in the group exposed to 0.8 mg Cd/L. The condition factor and the SFG appeared as sensitive biomarkers of health status and growth of the animals, respectively. Cadmium-exposed fish reduced food intake, which was reflected in a decreased assimilation with concomitant decline in the external energy supply from feeding. Our results highlight the importance of considering the metabolic status of the test organisms when analyzing the responses of the biomarkers usually used as effect parameters in ecotoxicological evaluations under experimental conditions.

Use of integrated biomarker indexes for assessing the impact of receiving waters on a native neotropical teleost fish

In the field of aquatic ecotoxicology, indexes obtained from a battery of biomarkers have proved to be a useful tool for assessing quantifiable and integrated health responses of organisms exposed to pollutants. The objective of this work was to evaluate the effects of exposure to the Reconquista River water (RR) on adults of Cnesterodon decemmaculatus using different integrated indexes. We conducted a 12-d laboratory assay involving the exposure of fish to RR, a negative control (moderately hard water - MHW medium), and a positive control (for genotoxicity with MHW + Cyclophosphamide, CP). There were measured metabolic (food intake and specific assimilation, specific metabolic rate, oxygen extraction efficiency, ammonia excretion, and ammonia quotient), genotoxic (comet assay, micronucleus test, and nuclear abnormalities), morphological variables (total length, body and liver weight) and biochemical variables (Electron Transport System - ETS, Acetylcholinesterase activity - AChE, Catalase - CAT, Glutathione-S-transferase - GST, Glutathione content - GSH and tissue proteins). These variables were grouped into different indexes: morphological (Condition Factor - K and Liver Somatic Index-LSI), metabolic (Scope for Growth-SFG), genetic damage (GDI) and integrated biomarker response - IBR (AChE brain, CAT, GST and GSH liver, GSH gills, ETS muscle) indexes. Results indicated that RR water induced metabolic, biochemical and genetic damages. The SFG, GDI and IBR were suitable to assess the effects of exposure to an environmental sample in an integrated approach, reducing uncertainty due to inherent biomarker variability. These indexes have emerged as promising tools for environmental monitoring studies.

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.