Evaluation of the Acute Effects of Arsenic on Adults of the Neotropical Native Fish Cnesterodon decemmaculatus Using a Set of Biomarkers.

Neotropical fish Cnesterodon decemmaculatus were exposed to different sublethal concentrations (0.5, 1.0 and 5.

Acute toxicity of cadmium to freshwater fishes and its relationship with body size and respiratory strategy.

Acute toxicity assays in freshwater fishes are used in diverse local and regional regulations. Lethality is a complex biological process, depending on both extrinsic and intrinsic factors. The extrinsic parameters (pH, temperature, hardness and alkalinity, among others) have been widely studied and their influence on toxicity has been well characterized.

First baseline for bioenergetic biomarkers in Cnesterodon decemmaculatus as test organism in ecotoxicological studies.

Cnesterodon decemmaculatus is a Neotropical teleost fish frequently used in ecotoxicological evaluations, whose biology has been thoroughly studied. Although there is considerable information on its response to different toxicants, no range of reference values has been so far established for the different biological parameters proposed as biomarkers of effect or exposure. Moreover, no study has yet examined the possible influence of the metabolic status of the exposed animals on their response to toxic stress.

Histological, Genotoxic, and Biochemical Effects on (Jenyns 1842) (Cyprinodontiformes, Poeciliidae): Early Response Bioassays to Assess the Impact of Receiving Waters.

In the present study, the toxicity of receiving waters from a highly polluted urban watercourse, the Reconquista River, Argentina, collected at a dam in the upstream part of the river was evaluated. a widely distributed fish species in Pampasic rivers proposed for use in ecotoxicological evaluations, was used as a test organism. A 96-h acute toxicity bioassay with river water quality which has been characterized as moderately contaminated was performed.

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).

Susceptibility of Chordodes nobilii (Gordiida, Nematomorpha) to three pesticides: Influence of the water used for dilution on endpoints in an ecotoxicity bioassay.

The increased use of pesticides during recent years necessitates a reevaluation of the effect of those compounds by extending the range of nontarget species commonly used in risk assessment. In the present work, we thus determined the impact of the pesticides glyphosate, carbendazim, and malathion on the parasite Chordodes nobilii in both natural and reconstituted freshwater as the assay medium and tested the sensitivity of three of this species's ecologically relevant parameters-e. g.

Infectivity of Chordodes nobilii larvae (Gordiida: Nematomorpha).

The gordiids are freshwater representatives of the parasite phylum Nematomorpha that function as a link between aquatic and terrestrial ecosystems. In recent years, different ecotoxicologic studies have been made with the South-American gordiid species, Chordodes nobilii, that have demonstrated the capacity of this group to act as a bioindicator of contamination. Despite the Gordiida’s ecologic relevance, further studies are still needed to elucidate different aspects of the biology of the class, and among those, the infective capacity, a parameter that can be evaluated by the infection index mean abundance (IIMA).

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.

Biomonitoring toxicity of natural sediments using juvenile Hyalella curvispina (Amphipoda) as test species: evaluation of early effect endpoints.

The utility of early effect endpoints as biomarkers of ecotoxicity of natural sediments in water-sediment static system was investigated. The particular goal was to evaluate the ecotoxicity of the sediment samples from La Choza stream, located in upper basin of the Reconquista river, the second most polluted river of Argentina. Native juveniles Hyalella curvispina were used as test organisms evaluating survival, growth, oxidative stress parameters (SOD; CAT, TBARS) and the electron transport system (ETS) activity as early toxic effect.

Biochemical responses of ecological importance in males of the austral South America amphipod Hyalella curvispina Shoemaker, 1942 exposed to waterborne cadmium and copper.

The use of physiological parameters as sensitive indicators of toxic stress from exposure to different pollutants is an important issue to be studied. Hyalella curvispina is a Neotropical amphipod often used in ecotoxicological evaluations. This work aimed to quantify biochemical responses of ecological importance in H.

Cnesterodon decemmaculatus juveniles as test organisms in toxicity assessment: cadmium case.

The poeciliid Cnesterodon decemmaculatus is one of the native species of southern South America recently recommended for use as a test species in biomonitoring. Therefore, it is important to characterize its responses to stress conditions caused by pollution. The aim of this work was to determine the toxicity of the reference toxicant cadmium (Cd) and to evaluate the lethality response of juveniles of C.

Cadmium toxicity assessment in juveniles of the Austral South America amphipod Hyalella curvispina.

Hyalella curvispina is representative of zoobenthic communities in Austral South America. It is taxonomically close to Hyalella azteca and abundant in fresh water bodies of the pampasic region of Argentina. It is usually used as test organism in ecotoxicological studies at a regional level, and there is a strong concern to increase the knowledge of both their biology and their sensitivity to different toxic agents.

Non-point contamination homogenizes the water quality of pampean streams.

The aim of this research was to study the effects on streams water quality of non-point contamination as agriculture and cattle farming activities at a basin with pampean characteristics located at the upper Reconquista River Basin. Eight reaches with different uses in their neighboring zones were selected with the proposed to detect differences at the water quality among them. SRP range was 0-0.

Cadmium toxicity in tadpoles of Rhinella arenarum in relation to calcium and humic acids.

Bioassays were carried out to study the differences in cadmium (Cd) toxicity to premetamorphic tadpoles of Rhinella arenarum, in aqueous solutions with variable contents of calcium in the presence and absence of humic acids, and to analyze the relationship between the free Cd(2+) ion concentrations calculated by chemical modeling and the biological results. The correlation analysis of the free Cd(2+) concentration calculated by chemical speciation and the analytical Cd yielded a direct relationship between the degree of toxicity and the slope value. The lowest slope was obtained from the treatments with lowest free Cd(2+) ion concentration and lowest toxicity, whereas the highest slope was obtained from the most toxic treatment.

Validation test with embryonic and larval stages of Chordodes nobilii (Gordiida, Nematomorpha): sensitivity to three reference toxicants.

Chordodes nobilii is a parasite whose pre- and postparasitic stages are found in different types of freshwater bodies. Due to the peculiarities of its life cycle, it acts as a link between freshwater bodies and terrestrial ecosystems. There is little toxicological information on the group Gordiida.

Sensitivity of preparasitic stages of Chordodes nobilii (Gordiida, Nematomorpha) to malathion.

The largest part of the life cycle of Gordiida, known as horsehair worms, occurs in aquatic environments usually affected by agricultural activities. The free-living adults reproduce in freshwater environments, where preparasitic larvae undergo development. Since malathion is an insecticide used in the distribution area of Chordodes nobilii, the aim of this study is to evaluate the effect of malathion concentrations which might be expected in the environment on preparasitic stages of this species.

Copper toxicity on juveniles of Hyalella pseudoazteca González and Watling, 2003.

The aim of this work is to evaluate the toxic effect of water and sediment contaminated with Cu(2+) on the survival and growth of juveniles of Hyalella pseudoazteca. The LC(50) 96 h for Cu(2+) in moderately hard water was 0.17 mg/L.

Toxicity of the herbicide glyphosate to Chordodes nobilii (Gordiida, Nematomorpha).

Nematomorpha (horsehair worms) is a poorly known group of worm-like animals similar to nematodes. Adults are free-living and reproduction takes place in freshwater environments, where preparasitic larvae undergo development. All species have a parasitic juvenil stage and infection may result in the host's death, insects being the most frequent host.

Assessment of the pollution impact on biomarkers of effect of a freshwater fish.

Changes in biomarkers of fish captured from stressed environments may represent a reliable tool in revealing sublethal effects of the pollutants found in aquatic ecosystems. The response patterns of selected biochemical and morphological variables biomarkers of effect were assessed in adult females of an indigenous teleost Cnesterodon decemmaculatus, caught at a polluted site (San Francisco) of the Reconquista river (Buenos Aires, Argentina). Combined field-caging experiments with controlled laboratory exposure to clean media were performed.

Biomarkers of a native fish species (Cnesterodon decemmaculatus) application to the water toxicity assessment of a peri-urban polluted river of Argentina.

Environmental monitoring by means of biomarker parameters assessed in different species is a useful tool. It has the advantage of providing a quantitative response as well as valuable information of ecological relevance on the chronic adverse effects caused by water pollution. The aim of this study was to assess the response of biochemical and physiological parameters of Cnesterodon decemmaculatus, a native teleost, simultaneously caught in two sites of Reconquista river, a highly polluted peri-urban river.