Toxicity ranking of estuarine sediments on the basis of Sparus aurata biomarkers

Biokinetics of the anionic surfactant linear alkylbenzene sulfonate (LAS) in the marine fish Sparus aurata: Investigation via seawater and food exposure pathways

Uptake and depuration kinetics of [¹⁴C]C₁₂-6-linear alkylbenzene sulfonate (LAS) in the fish Sparus aurata were determined during experimental exposure via seawater or food separately under laboratory conditions. The fish concentrated LAS from seawater (using realistic contaminant concentrations) with a mean BCF value of 20 ± 2 L kg^-1 reached within 3 days and following a one-compartment exponential model. High differences in BCF were noted among organs, with values ranking in the order gall bladder (1400 ± 600 L kg^-1) >>  digestive tract (52 ± 9 L kg^-1) > liver (38 ± 4 L kg^-1) > gills (16 ± 3 L kg^-1) > skin (13 ± 2 L kg^-1) > head (9 ± 1 L kg^-1) > muscles (4 ± 1 L kg^-1). After three days of exposure, ¹⁴C activity decreased in gall bladder while it remained constant in other organs. Biotransformation and elimination processes could explain this phenomenon observed in gall bladder. LAS depuration was rapid in all organs (with up to 90% elimination within 2 days) and depuration kinetics was best fitted by a two-compartment exponential-model. When fish were fed with radiolabeled food, ingested LAS was transferred to organs within the first hours following the feeding. Model best describing depuration kinetics of LAS in the whole fish indicated that the contaminant can be considered as not assimilated.

Effects of metal contamination in situ on osmoregulation and oxygen consumption in the mudflat fiddler crab Uca rapax (Ocypodidae, Brachyura)

The contamination of estuaries by metals can impose additional stresses on estuarine species, which may exhibit a limited capability to adjust their regulatory processes and maintain physiological homeostasis. The mudflat fiddler crab Uca rapax is a typical estuarine crab, abundant in both pristine and contaminated areas along the Atlantic coast of Brazil. This study evaluates osmotic and ionic regulatory ability and gill Na(+)/K(+)-ATPase activity in different salinities (<0.5, 25 and 60‰ S) and oxygen consumption rates at different temperatures (15, 25 and 35°C) in U. rapax collected from localities along the coast of São Paulo State showing different histories of metal contamination (most contaminated Ilha Diana, Santos>Rio Itapanhaú, Bertioga>Picinguaba, Ubatuba [pristine reference site]). Our findings show that the contamination of U. rapax by metals in situ leads to bioaccumulation and induces biochemical and physiological changes compared to crabs from the pristine locality. U. rapax from the contaminated sites exhibit stronger hyper- and hypo-osmotic regulatory abilities and show greater gill Na(+)/K(+)-ATPase activities than crabs from the pristine site, revealing that the underlying biochemical machinery can maintain systemic physiological processes functioning well. However, oxygen consumption, particularly at elevated temperatures, decreases in crabs showing high bioaccumulation titers but increases in crabs with low/moderate bioaccumulation levels. These data show that U. rapax chronically contaminated in situ exhibits compensatory biochemical and physiological adjustments, and reveal the importance of studies on organisms exposed to metals in situ, particularly estuarine invertebrates subject to frequent changes in natural environmental parameters like salinity and temperature.

Assessing pollution in marine protected areas: the role of a multi-biomarker and multi-organ approach

Marine protected areas (MPAs) are vulnerable to many pressures, including pollution. However, environmental quality monitoring in these areas traditionally relies on only water chemistry and microbiological parameters. The goal of the current study was to investigate the role of a set of biomarkers in different target organs (liver, kidney, and gills) of fish in order to assess the environmental quality of an MPA (MTs, GPx, GST, GSH, DNA damage, LPO, AChE, and condition index). Chemical analyses were also performed on liver and muscle tissues to evaluate metal body burdens, and PAHs were identified in bile. A demersal fish (Cathorops spixii) that is widely consumed by the local population was used as bioindicator species, and the results were integrated using multivariate analysis. The use of the biomarker approach allowed for the identification of both seasonal and spatial variations in pollution sources around the Environmental Protected Area of Cananéia-Iguape-Peruíbe (APA-CIP). Higher metal body burdens associated with biological responses were found in the sites under the influence of urban areas during the dry season, and they were found in the sites under the influence of the Ribeira de Iguape River (RIR) during the rainy season. The liver was found to be more responsive in terms of its antioxidant responses, whereas gills were found to be more responsive to biomarkers of effect. These results show that this set of biomarker analyses in different organs of fish is a useful tool for assessing chemical pollution in an MPA.

Comparative assessment of in vitro and in vivo toxicity of azinphos methyl and its commercial formulation

The toxic effects of Gusathion (GUS), which is a commercial organophosphate (OP) pesticide, and also its active ingredient, azinphos methyl (AzM), are evaluated comparatively with in vitro and in vivo studies. Initially, the 96-h LC50 values of AzM and GUS were estimated for two different life stages of Xenopus laevis, embryos, and tadpoles. The actual AzM concentrations in exposure media were monitored by high-performance liquid chromatography. Also, the sub-lethal effects of these compounds to tadpoles were determined 24 h later at exposure concentrations of 0.1 and 1 mg/L using selected biomarker enzymes such as acetylcholinesterase (AChE), carboxylesterase (CaE), glutathione S-transferase (GST), glutathione reductase, lactate dehydrogenase, and aspartate aminotrasferase. Differences in AChE inhibition capacities of AzM and GUS were evaluated under in vitro conditions between frogs and fish in the second part of this study. The AChE activities in a pure electrical eel AChE solution and in brain homogenates of adult Cyprinus carpio, Pelophylax ridibundus, and X. laevis were assayed after in vitro exposure to 0.05, 0.5, 5, and 50 mg/L concentrations of AzM and GUS. According to in vivo studies AChE, CaE and GST are important biomarkers of the effect of OP exposure while CaE may be more effective in short-term, low-concentration exposures. The results of in vitro studies showed that amphibian brain AChEs were relatively more resistant to OP exposure than fish AChEs. The resistance may be the cause of the lower toxicity/lethality of OP compounds to amphibians than to fish.

Identification of the toxic constituents of sediments in a Brazilian subtropical estuary

Phase 1 of the TIE method was applied to samples of elutriates from sediments of the Itajaí-Açu estuary and adjacent coastal region in southern Brazil. Embryo-larval toxicity assays were used with the sea urchin Arbacia lixula in samples of raw elutriate, and treated with Ulva fasciata, EDTA and sodium thiosulfate. Inside the estuary, ammonia was responsible for more than 40% of the toxicity in both the dredged and undredged regions. A toxicity gradient was observed, between the estuary and the coastal region, with an increase in the importance of metals for the latter. Temporally, there is strong evidence of the influence of dredging and disposal of sediments in the contamination of the coastal dumping site. The results indicating that this area presents limitations in its saturation capacity. Chemical analysis indicated the metal Cu is probably responsible for the toxicity of the sediments observed, without the interference of ammonia.

Comparative toxicity of methidathion and glyphosate on early life stages of three amphibian species: Pelophylax ridibundus, Pseudepidalea viridis, and Xenopus laevis

The assessments of pesticide toxicity on nontarget organisms have largely been focused on the determination of median lethal concentration (LC50) values using single/laboratory species. Although useful, these studies cannot describe the biochemical mechanisms of toxicity and also cannot explain the effects of pesticides on natural species. In this study, the toxic effects of glyphosate and methidathion were evaluated comparatively on early developmental stages of 3 anurans-2 natural (Pelophylax ridibundus, Pseudepidalea viridis) and 1 laboratory species (Xenopus laevis). The 96-h LC50 values for methidathion and glyphosate were determined as 25.7-19.6 mg active ingredient (AI)/L for P. viridis, 27.4-22.7 mg AI/L for P. ridibundus, and 15.3-5.05 mg AI/L for X. laevis tadpoles. Furthermore, as early signs of intoxication, glutathione S-transferase (GST), acetylcholinesterase (AChE), carboxylesterase (CaE), glutathione reductase, lactate dehydrogenase, and aspartate aminotrasferase were assayed in 4-day-old tadpoles after 96-h pesticide exposure. The GST induction after 3.2mg AI/L methidathion exposure was determined to be 173%, 83%, and 38% of control, and the AChE inhibition for the same dose was determined to be 86%, 96%, and 30% of control for P. ridibundus, P. viridis, and X. laevis, respectively. Unlike the application of methidathion, all enzyme activities showed statistically significant increases on glyphosate exposure compared to controls. However, these increases in enzyme activities were not shown to be parallel with the increase of concentration. The levels of increases of GST and AChE were determined to be 111% and 31% for P. ridibundus, 13% and 51% for P. viridis, and 15% and 36% for X. laevis after 3.2mg AI/L glyphosate exposure, respectively. The findings of the study suggest that the most sensitive species to pesticide exposure is X. laevis. The selected biomarker enzymes AChE, CaE, and GST are useful in understanding the toxic mechanisms of these pesticides in anuran tadpoles as early warning indicators.

Biochemical response to exposure to six textile dyes in early developmental stages of Xenopus laevis

The present study was undertaken to determine the toxic effect of a lethal concentration of six different commercially used textile dyes on the 46th stage of Xenopus laevis tadpoles. The tadpoles were exposed to Astrazon Red FBL, Astrazon Blue FGRL, Remazol Red RR, Remazol Turquoise Blue G-A, Cibacron Red FN-3G, and Cibacron Blue FN-R for 168 h in static test conditions, and thus, 168-h median lethal concentrations (LC(50)s) of each dye were determined to be 0.35, 0.13, 112, 7, 359, and 15.8 mg/L, respectively. Also, to evaluate the sublethal effects of each dye, tadpoles were exposed to different concentrations of dyes (with respect to 168-h LC(50)s) for 24 h. The alteration of selected enzyme activities was tested. For this aim, glutathione S-transferase (GST), carboxylesterase, and lactate dehydrogenase (LDH) were assayed. After dye exposure, the GST induction or inhibition and LDH induction indicated some possible mechanisms of oxidative stress and deterioration in aerobic respiration processes induced by the tested dyes. Findings of the study suggest that selected biomarker enzymes are useful in understanding the toxic mechanisms of these dyes in X. laevis tadpoles as early warning indicators. Therefore, these selected biomarkers may evaluate the effect of environmental factors, such as textile dye effluents and other industrial pollutants, on amphibians in biomonitoring studies.

Evaluation of spatial and temporal changes in biomarker responses in the common carp (Cyprinus carpio L.) for biomonitoring the Meriç Delta, Turkey

The aim of this study is to examine the activity of several biomarkers in carp, Cyprinus carpio L., to determine their response to xenobiotics, such as organochlorine pesticides (OCPs), in the Meriç Delta. Fish were collected from contaminated sites and from areas regarded as relatively less contaminated in four sampling periods. Hepatic glutathione S-transferase (GST), carboxylesterase (CaE), lactate dehydrogenase, aspartate aminotransferase, and acid phosphatase activities were measured as biomarkers in the fish. For all fish, the condition factor and hepatosomatic index, were calculated to determine the condition of the fish. The results of this study indicated that the mean GST activity showed an increase in fish from the Meriç-Ergene junction site and a decrease in Enez site with respect to fish from Meriç site. Furthermore, the study shows that spatial and temporal changes of biomarkers such as GST and CaE might be useful for the assessment of environmental contamination in the Meriç Delta.

Risks of seawater ozonation in recirculation aquaculture--effects of oxidative stress on animal welfare of juvenile turbot (Psetta maxima, L.)

Ozone is frequently used for water treatment and disinfection in recirculating aquaculture systems. However, due to the fragmentary data on chronic toxicity of ozone produced oxidants (OPO) and its safe concentrations, the daily application of ozone in aquaculture is challenging. To evaluate the chronic effects of sublethal OPO concentrations, juvenile turbot (Psetta maxima, L.) were exposed to OPO concentrations of 0.06, 0.10 and 0.15 mg/l for 21 days. Gills were analysed for histopathological alterations and mRNA expression of heat shock protein 70 (hsp70), hsp90 as well as glutathione-S-transferase (gst) were determined in the gills and the liver after 1d, 7d and 21 d. Histopathologic findings confirmed adverse effects at 0.10-0.15 mg/l, but these (necrosis, lamellar clubbing, hypertrophy, hyperplasia) could only be observed after an extended exposure (mostly 21 d), and were considered as irreversible tissue damage. Hsp70 expression in the gills was only significantly increased at the highest OPO concentration (0.15 mg/l) on 1d and 7d, and returned to basic levels until day 21. Hsp90 mRNA was already increased at 0.10mg/l after 1 and 7 days of exposure, and again was comparable to the control group on day 21. In contrast, elevated gst mRNA expression was only observed on day 7 at 0.10mg and 0.15 mg/l. Although similar trends were observed in the liver for all markers, differences were only significant in exceptional cases due to the high individual variation observed. Thus, mRNA expression in the gills rather than in the liver is recommended as a marker to characterize OPO-induced oxidative stress in turbot. It has to be noted that mRNA expression returned to basic levels on day 21 regardless the actual OPO concentration, suggesting a collapse of adaptive mechanisms as a possible explanation for the observed tissue damage.

Validating a multi-biomarker approach with the shanny Lipophrys pholis to monitor oil spills in European marine ecosystems

Oil spills are an importance source of polycyclic aromatic hydrocarbons (PAHs) in the aquatic environment. Intertidal communities are particularly sensitive since most organisms from these ecosystems are sessile or present reduced mobility. Hence, it is important to validate the use of resident species as sentinels to characterize the impact of oil spills on the rocky shores and the improvement during the restoration process. Recently the advantages of using the shanny Lipophrys pholis in pollution monitoring within the northwestern Atlantic coast has been pointed out. Therefore, with the aim of further validating the use of L. pholis in pollution monitoring associated with petrogenic hydrocarbon contamination, a multi-biomarker approach study was carried out 1 week after a moderate oil spill from the waste treatment plant (WTP) of the major Portuguese refinery in the north of Portugal (Petrogal). Fish collected at 2 km from the accident displayed a significant induction of ethoxyresorufin-O-deethylase activity (EROD) and fluorescent aromatic compounds (FACs) in bile (up to a 5-fold induction) in comparison with the pre-spill scenario, and a 15% induction in erythrocytic nuclear abnormalities (ENA), a biomarker of genotoxicity. In contrast, no significant differences were recorded in the reference site. In order to better characterize the time-course accumulation of FACs in bile after a PAH insult, laboratory exposure of L. pholis to benzo[a]pyrene (B[a]P) was performed. A clear dose-response accumulation of B[a]P metabolites was observed that closely reflected nominal exposure concentrations already after 3d. Overall, the findings of the present study highlight the potential of L. pholis in pollution monitoring dealing not only with chronic contamination, but also with oil spill accidents of a moderate scale. Taking into consideration that EROD and FACs determinations in L. pholis are cost effective, rapid and easy to use, they offer a great potential to be incorporated into risk assessment of PAHs in the scope of national monitoring programs and the European Water Policy legislation.