Lucrecia Ferrari

Biomarkers assessment in juvenile Cyprinus carpio exposed to waterborne cadmium

The impact of long-term exposure to waterborne cadmium (Cd) on Cyprinus carpio was evaluated through changes of selected parameters considered as biomarkers of toxicity. Fish were exposed to 1.6 mg l(-1) Cd for 14 days and then transferred to Cd-free water for 19 days. The measured parameters were gill ATPases, brain acetylcholinesterase (AchE), liver glutamate oxaloacetate (GOT) and glutamate pyruvate (GPT) transaminases, muscle water content, and protein content of liver, gills and brain. Condition factor and liver somatic index were also calculated. Branchial ATPase activities were impaired in a dissimilar way: the (Na(+),K(+))-ATPases were inhibited by approximately 30%, while the Mg(2+)-ATPase was significantly activated by 70%. Brain AchE showed no changes after Cd exposure. Both liver GOT and GPT activities were increased by the metal by 63 and 98%. Water content of the skeletal muscle showed no significant alterations. After the 19-day recovery phase, changes in the Mg(2+)-ATPase and GPT were reversed to values similar to controls, but the Cd exposure resulted in an irreversible alteration in GOT activity. Results indicate that the sublethal Cd concentrations are stressful to carp, particularly with reference to branchial enzymes which may disrupt the osmotic and ionic balance of the animals.

Freshwater pollution biomarker: response of brain acetylcholinesterase activity in two fish species ☆

The effect of prolonged exposure at two sites along the Reconquista River (Argentina), a highly polluted peri-urban water body, on brain acetylcholinesterase (AChE, EC 3.1.1.7, acetylcholine acetylhydrolase) of two teleosts was examined. Caged Cyprinus carpio and field-captured Cnesterodon decemmaculatus were used as sentinel organisms. Eserine concentration inhibiting 50% of AChE activity (IC50) and inhibition kinetic parameters were also evaluated. Interspecies IC50 differences were found to agree with observed kinetic parameters (KA, ki and kc), indicating that carps were more sensitive to eserine. Data obtained disclosed spatial differences and demonstrated the high sensitivity of AChE activity as an exposure biomarker. Marked species-related differences were detected, showing that enzyme determination of C. decemmaculatus is more effective in highly polluted sites. Considering the river water physicochemical profile, observed changes in AChE activities can be partly attributed to long-lasting raised concentrations of dissolved heavy metals.

Enzyme activities as biomarkers of freshwater pollution : Responses of fish branchial (Na + K)-ATPase and liver transaminases

The water toxicity of the Reconquista river, an urban and industrial polluted watercourse was tested. Surface water samples from two points up and downstream of low and high pollution conditions were assayed. Continuous‐flow renewal bioassays under controlled laboratory conditions were run for 21 days. Alterations in the activity of enzymes involved in ion balance and hepatic metabolism were determined in juvenile carp Cyprinus carpio used as test species. Branchial (Na+K)‐ATPase and hepatic glutamic oxalacetate transaminase (GOT) and glutamic pyruvate transaminase activities were the selected biomarkers of toxicity. Sublethal Cd solutions were used as a reference toxic. Results showed that the activity of the enzymes were affected according to the deterioration of the river water quality. Branchial (Na+K)‐ATPase and liver GOT activity results were reliable indicators to discriminate river water samples of dissimilar pollution state. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 313–319, 1999

Effect of temperature and salinity on larval development of southern king crab (Lithodes antarcticus)

Larvae of Lithodes antarcticus Jacquinot were reared in October, 1981 from hatching to the glaucothoe stage at 16 temperature/salinity combinations (5.5°; 7.5°; 9.5° and 13.5°C; 26, 29, 32 and 35‰ S) to determine optimal environmental conditions for larval development. The highest survival percentage was obtained in the culture at 7.5°C and diminished according to temperature increase or decrease. High temperature cultures significantly shorten the larval life duration, but produce large mortalities. At 5.5°C mortality occurred almost exclusively during the moult to glaucothoe stage. Higher survival percentages were obtained as salinity was increased. In the lowest salinity culture (26‰ S) no zoea reached the post-larvae stage at culture temperatures. The best T/S combination was obtained at 7.5°C and 35‰ S, with a survival percentage of 29%. The shortest zoeal developments were obtained at 32‰ S in all culture temperatures. Salinity also affects larvae coloration: there is a pigment concentration on erythrophores, which causes a color decrease.

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 hosts death, insects being the most frequent host. Most of the life cycle occurs in freshwater environments, which are often contaminated by different pollutants. Based on the lack of information on the toxicity of herbicides to horsehair worms, the objective of this study is to evaluate the effect of different concentrations of glyphosate (technical grade and formulated product) on Chordodes nobilii (Gordiida, Nematomorpha). Bioassays were performed with embryos and larvae (preparasitic stages), and adults (postparasitic stage). Test organisms were exposed for a short period of time to concentrations ranging between 0.1 and 8 mga.e.l(-1) of glyphosate (technical and formulated). Although embryo development was not inhibited, there was a significant decrease in the infective capacity of larvae derived from eggs that had been exposed to >or= 0.1mg/l. Similar results were obtained for directly exposed larvae. No differences in toxicity were detected between the active ingredient and formulated product. Adult exposed for 96 h to 1.76 mgl(-1) formulated Gly shown a mortality of 50%. Results indicate that C. nobilii is affected at glyphosate concentrations lower than those expected to be found in freshwater environments and those specified in the legislation.

Age-related differential sensitivity to cadmium in Hyalella curvispina (Amphipoda) and implications in ecotoxicity studies

The standardization of toxicity tests requires the selection of the most suitable test species and their developmental stages, as well as the selection of the appropriate assay matrix and the evaluation of the sensitivity of the test species to the reference toxicants. International protocols recommend the use of the amphipod Hyalella azteca from the Northern Hemisphere for sediment toxicity tests. We selected the widely distributed amphipod Hyalella curvispina, representative of pleustonic, epiphitic and zoobenthic assemblages in austral South America, as test species to be used in regional studies. Our goals were to evaluate the sensitivity of three developmental stages of H. curvispina to cadmium as a reference toxicant and to select the most suitable age and exposure time for aquatic ecotoxicity assessment. The three ages were highly susceptible to cadmium, with sensitivities: neonates > adults > juveniles. Our results validate the use of the native H. curvispina as a standard species for ecotoxicological assessment studies.

Tadpoles assay: its application to a water toxicity assessment of a polluted urban river.

The acute toxicity assay with premetamorphic tadpoles of Bufo arenarum as sentinel organism was applied to evaluate the quality of two water samples taken from three sites of theReconquista River, an urban watercourse which is recipient ofboth untreated industrial effluents and domestic wastes. Theresults of the 96 hr bioassays were compared with thephysicochemical parameters determined in the samples.Mortality rates in each sample were compared using the Bonferronis test and a stepwise regression analysis of mortality andphysicochemical parameters was done. In this way, it was possible to build up consistent descriptive models which showedthat pH, Cl-, Cd2+ and Cu2+ concentrations in theriver water were significant independent variables and mightexplain, under the experimental conditions, the recordedtoxicity effects of the tested samples.Because of its simplicity, low cost and reliability it wassuggested the tadpoles bioassay be included in the set of testsused in integrated program of freshwater pollution.

Long-term in situ Toxicity Bioassays of the Reconquista River (Argentina) Water with Cyprinus carpio as Sentinel Organism

The toxicity of the Reconquista River water at Cascallares, a relatively low polluted point, was determined by means of bioassays with juvenile Cyprinus carpio as a test organism. During the summer of 1995–1996, three 30 days-long in situ caged fish tests were conducted. Changes in the activities of branchial (Na+,K+)- and Mg++-ATPases and brain AchE offish were studied. The chemical profile of the river water showed that heavymetals and phenols were the main pollutants. Gill ATPases activities were altered, while brain AchE activity resulted inhibited in one of the assays. (Na+,K+)-dependent activity was inhibited approximately 20% as compared with controls; in two assays Mg++-ATPase activity was stimulated. The condition factor of caged fish did not differ from controls.Since the protein content of gills was slightly altered, the detected changes in the enzyme activity should not be linked to alterations in the protein synthesis.

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. The aim of the present work was to assess the effects of cadmium on H. curvispina juveniles exposed to concentrations expected in the water bodies of the distribution area of the species. Survival, growth and cadmium body burden were evaluated in aqueous and solid matrices under fixed experimental conditions. Animals were exposed in ten-day static toxicity bioassays to 2.5, 5.25 and 11.25 μg Cd/L for the aqueous-phase bioassays, and to 0.85, 2.8 and 5.6 mg Cd/Kg dry sediment for the solid-phase bioassays. In water only assays, the animals exposed to 11.25 μg Cd/L showed a significant decrease in survival and growth. In the sediment bioassays, no effect was observed on survival, and weight was significantly reduced at the highest concentration. Cadmium uptake was concentration dependent for both assay matrices and one order of magnitude higher in the aqueous medium than in the solid matrix. Results indicate that juveniles of H. curvispina are sensitive to cadmium concentrations expected in their environment and thus confirm their importance as test organisms for ecotoxicity assessment in water bodies within the distribution area of the species.

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. It is only known that embryos and larvae of C. nobilii are sensitive to glyphosate and malathion at relevant concentrations in the environment. On this basis, the aims of this study were to characterize the sensitivity of the pre-parasitic stages of C. nobilii to three reference toxicants: sodium dodecyl sulfate (SDS), cadmium chloride and potassium dichromate (Cr(6+)), and to validate a previous experimental protocol for ecotoxicological risk assessment. The protocol involved acute exposure of early embryonic stages and larvae to the three toxicants for 96 h and 48 h, respectively. Embryo development was inhibited only by Cr(6+) which presented a IC(50) of 0.71 mg Cr(6+)L(-1). The development of the eggs exposed to SDS and those exposed to cadmium chloride showed no differences as compared to that of controls. However, the infective capacity of larvae derived from the eggs exposed to the three toxicants was lower than that of controls. Larval survival was affected even at the lowest concentration of the three toxicants assayed. In relation to other freshwater organisms, C. nobilii can be characterized as an organism medium to highly sensitive to the toxicants tested.