Contaminants In Aquatic Organisms Research Articles

Interactions between multi-walled carbon nanotubes and plankton as detected by Raman spectroscopy

Raman spectroscopy has been commonly used in materials science to detect chemicals. Based on inelastic scattering of light after incident photons interact with a molecule, it has high potential for non-destructive detection of specific contaminants in living biological specimens. The increasing use of carbon nanotubes (CNTs) increases its chance to enter the aquatic habitats through direct discharge, surface runoff and atmospheric deposition, but their potential environmental impacts remain poorly known. We tested the use of Raman spectroscopy to investigate the interactions between multi-walled CNTs (MWCNTs) and aquatic plankton in vivo. For phytoplankton cells (Scenedesmus obliquus) that were exposed to MWCNTs, Raman spectroscopy was able to distinguish between background biological material and MWCNTs that adhere to the cells (G-band peak at 1590 cm−1 and D-band peak at 1350 cm−1 in the Raman spectra that were unique to MWCNTs). Harmful effects of MWCNT exposure manifested as lower photosynthetic efficiency and/or lower specific growth rate in the phytoplankton. MWCNT particles also adhered to the body surface of zooplankton, especially the carapace. Both Ceriodaphnia sp. and Daphnia sp. ingested MWCNTs directly, which was verified by the signature G-band and D-band Raman peaks in the zooplankton gut region. MWCNTs remained in the gut overnight after the zooplankton had been returned to clean water, showing that the zooplankton retained MWCNTs inside their body for an extended time, thereby increasing the chance to disperse and transfer the contaminants throughout the aquatic food web. Our results demonstrate that Raman spectroscopy is a promising method for non-destructive investigation of the uptake and dynamic fate of CNTs and other contaminants in aquatic organisms.

Microplastics aggravate the bioaccumulation and toxicity of coexisting contaminants in aquatic organisms: A synergistic health hazard

There are ongoing controversies regarding the effects of microplastics (MPs) on the bioaccumulation and toxicity of coexisting contaminants in aquatic organisms. This study aims to quantitatively evaluate this issue based on 870 endpoints from 40 publications. It was shown that the presence of MPs significantly increased the bioaccumulation of co-contaminants by 31%, with high statistical power and without obvious publication bias. The aggravated bioaccumulation was also revealed by the strongly positive correlation between bioconcentration factors in the presence and the absence of MPs. Furthermore, the subgroup/regression analyses indicated that the vector effect of MPs on other chemicals was affected by multiple factors and their interactions, such as particle size and exposure time. In addition, a relatively comprehensive biomarker profile was recompiled from included studies to assess the changes in toxicity caused by combined exposure. Results confirmed that the presence of MPs obviously exacerbated the toxicity of co-contaminants by 18%, manifested by the potentiated cytotoxicity, endocrine disruption, immunotoxicity and oxidative stress, implying a synergistic health hazard. Ultimately, the mismatches between laboratory and field conditions were discussed, and the recommendations for future research were offered.

Genotoxic effect of dimethylarsinic acid and the influence of co-exposure to titanium nanodioxide (nTiO2) in Laeonereis culveri (Annelida, Polychaeta)

Few data are available about the effect of dimethylated forms (DMA) on aquatic organisms. As rarely a contaminant occurs alone, studies evaluating the combined effect of different contaminants in aquatic organisms are needed. In fact, the presence of nanomaterials, such as titanium dioxide nanoparticles (nTiO2), in the aquatic environment is now a reality due to its intensive production and use. So, this study evaluated the toxicological effects of DMA in an acute exposure condition and considered the potential influence of nTiO2 on the effects induced by DMA in the polychaete, Laeonereis culveri. The animals were exposed over 48 h to DMA (50 and 500 μg/l) alone or in combination with nTiO2 (1 mg/l). Biochemical parameters such as concentration of reactive oxygen species (ROS), glutathione-S-transferase (GST) activity, levels of reduced glutathione levels (GSH) and macromolecular (lipid and DNA) damage were evaluated, as well the DNA repair system. In addition, the accumulation of total As and the chemical speciation of the metalloid in the organisms was determined. The results showed that: (1) only the group exposed to 500 μg of DMA/l accumulated As and when co-exposed to nTiO2, this accumulation was not observed. (2) The levels of ROS increased in the group exposed to 50 μg/l of DMA alone and the effect was reversed when this group was co-exposed to nTiO2 (3) None of the treatments showed altered GST activity or GSH levels. (4) All groups that received nTiO2 (alone or in combination with DMA) showed lipid peroxidation. (5) The exposure to DMA (both concentrations) alone or in combination with nTiO2 induced DNA damage in L. culveri. These results showed that DMA exhibits a genotoxic effect and that co-exposure to nTiO2 had an influence on its toxicity. So the occurrence of both contaminants simultaneously can represent a threat to aquatic biota.

Is gene transcription in mussel gills altered after exposure to Ag nanoparticles?

Nanotechnology is a rapid field of development with the enhancement of the production of different types of nanoparticles (NPs) applied in several industrial and commercial applications which increase the risk of their presence in the aquatic environment. Ag NPs have a wide application in everyday life products. However, there is concern about the exposure effects on aquatic organisms to these NPs. Therefore, this study aims to assess gene transcription alterations in mussels Mytilus galloprovincialis gills exposed for 2 weeks to Ag NPs (42 ± 10 nm, 10 μg.L(-1)). The genes were selected based on previous biomarkers and proteomic results and included superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST), caspase 3/7-1 (CAS), cathepsin L (CATH), heat-shock protein 70 (HSP 70), cytochrome P450 4YA (CYP 4YA), the elongation factor (EF1), actin and α- tubulin. No significant changes in gene transcription profiles were observed after exposure of M. galloprovincialis to Ag NPs for 15 days. The lack of significant gene transcription responses is in light with previous results obtained for mussels exposed to these NPs and may be related to the fact that enzyme kinetics and relative abundance of proteins (increase of antioxidant enzymes and metalllothioneins (MTs) with the time of exposure) do not always directly reflect their relative mRNA levels. Nevertheless, their overall expression maintenance may signify that, at end of the exposure period (15 days), the transcription of the respective genes is no longer required, pointing out to a possible adaptation effect to nanoparticles or due to the levels of Ag NPs accumulated in this tissue at this exposure time. This study highlights that gene transcription application and role as an additional and/or alternative end point approach is important to understand the mode of action of these emergent contaminants in aquatic organisms. However, in future studies, the time window needs to be adjusted, as genes are likely to respond earlier to the nanoparticle exposure.

Oxidative damage and antioxidant defence parameters in the Antarctic bivalve Laternula elliptica as biomarkers for pollution impacts

The Antarctic continent is increasingly vulnerable to anthropogenic pollution; however, assessments of the impacts that chemical pollutants have on cold-adapted marine organisms are limited. Oxidative stress (OS) occurs when the rate of reactive oxygen species generation exceeds the scavenging capacity of an organism’s antioxidant (AO) system and is an important unifying feature underlying the toxicity of many chemical contaminants in aquatic organisms. The Antarctic bivalve Laternula elliptica is a widely distributed, infaunal filter-feeding organism. We analysed AO enzyme activities, levels of the molecular antioxidant glutathione, protein carbonylation and lipid peroxidation as OS biomarkers in L. elliptica from contaminant-impacted sites near McMurdo Station and the relatively pristine Cape Evans. The objective was to evaluate the effectiveness of these biomarkers for detecting contaminant stress in this cold-adapted marine invertebrate. The concentrations of total polycyclic aromatic hydrocarbons were quantified as a proxy for contamination and found to be elevated in gonad and muscle tissues from L. elliptica dwelling in contaminated sites. These individuals exhibited a greater degree of OS than those from the reference site, evidenced by increases in oxidative lipid and protein damage, as well as an upregulation of AO defences. Coincidentally, L. elliptica from the contaminated sites were significantly smaller in shell length (1.3-fold) than those from the reference site. Oxidative biomarkers proved to be useful indicators of contamination exposure in the present study and were used to document ongoing biological impacts from historic and current pollution in McMurdo Sound.

Interactive effects of nanoparticles with other contaminants in aquatic organisms: Friend or foe?

The increasing production and use of nanoparticles (NPs) will lead to their release into the aquatic environment, posing a potential threat to the health of aquatic organisms. Both in the water phase and in the sediments NPs could mix and interact with other pollutants, such as organic xenobiotics and heavy metals, leading to possible changes in their bioavailability/bioconcentration/toxicity. However, whether these interactive effects may lead to increased harmful effects in marine organisms is largely unknown. In this work, available data mainly obtained on carbon based NPs and n-TiO2, as examples of widespread NPs, in aquatic organisms are reviewed. Moreover, data are summarized on the interactive effects of n-TiO2 with 2,3,7,8-TCDD and Cd2+, chosen as examples of common and persistent organic and inorganic contaminants, respectively, in the model marine bivalve Mytilus. The results reveal complex and often unexpected interactive responses of NPs with other pollutants, depending on type of contaminant and the endpoint measured, as well as differences in bioaccumulation. The results are discussed in relation with data obtained in freshwater organisms. Overall, information available so far indicate that interactive effects of NPs with other contaminants do not necessarily lead to increased toxicity or harmful effects in aquatic organisms.

Interactive effects of n-TiO2 and 2,3,7,8-TCDD on the marine bivalve Mytilus galloprovincialis

Despite the growing concern over the potential biological impact of nanoparticles (NPs) in the aquatic environment, little is known about their interactions with other pollutants. The bivalve Mytilus sp, largely utilized as a sentinel for marine contamination, has been shown to represent a significant target for different types of NP, including n-TiO2, one of the most widespread in use. In this work, the possible interactive effects of n-TiO2 and 2,3,7,8-TCDD, chosen as models of NP and organic contaminant, respectively, were investigated in Mytilus galloprovincialis. In vitro experiments with n-TiO2 and TCDD, alone and in combination, were carried out in different conditions (concentrations and times of exposure), depending on the target (hemocytes, gill cells and biopsies) and the endpoint measured. Mussels were also exposed in vivo to n-TiO2 (100μgL−1) or to TCDD (0.25μgL−1), alone and in combination, for 96h. A wide range of biomarkers, from molecular to tissue level, were measured: lysosomal membrane stability and phagocytosis in hemocytes, ATP-binding cassette efflux transporters in gills (gene transcription and efflux activity), several biomarkers of genotoxicity in gill and digestive cells (DNA damage, random amplified polymorphic DNA-RAPD changes), lysosomal biomarkers and transcription of selected genes in the digestive gland. The results demonstrate that n-TiO2 and TCDD can exert synergistic or antagonistic effects, depending on experimental condition, cell/tissue and type of measured response. Some of these interactions may result from a significant increase in TCDD accumulation in whole mussel organisms in the presence of n-TiO2, indicating a Trojan horse effect. The results represent the most extensive data obtained so far on the sub-lethal effects of NPs and organic contaminants in aquatic organisms. Moreover, these data extend the knowledge on the molecular and cellular targets of NPs in bivalves.

The effect of shore location on biomarker expression in wild Mytilus spp. and its comparison with long line cultivated mussels

Biomarkers are a common tool in the assessment of potential effects of contaminants in aquatic organisms. In order to identify the effects of anthropogenic pollution it is essential to identify background levels and to know the range of natural variability in the biomarker response. In this study, we examined various biomarkers of stress (glutathione S-transferase and metallothionein), damage (lipid peroxidation (LPO) and DNA damage (DNA)) and reproduction (vitellin-like proteins) in marine mussels (Mytilus spp.) from four locations along a vertical transect from high to low shore and compared them with cultivated long line mussels. High shore and cultivated mussels showed significantly higher LPO and DNA damage expression than the low shore mussels indicating a level of oxidative stress resulting from mussel location. Significant effects in physiological endpoints were also found. This study highlights the need to consider the diversity of natural environmental stress factors when using biomarkers in environmental assessment.

Proteomics: present and future in fish, shellfish and seafood

AbstractThe aim of proteomics is to simultaneously resolve all potential proteins expressed by a cell, tissue or organism in a specific physiological condition. It will allow scientists to build and test better hypotheses, with the ultimate goal to find better solutions to challenges in agricultural sciences, medicine and environmental management. Recent and very promising applications of proteomics have also been provided in the field of aquaculture, such as the search for antigenic proteins, the detection of differentially regulated proteins and the characterization of biologically active proteins primarily to investigate the physiology, development biology and impact of contaminants in aquatic organisms. Thus, a brief overview of present classical proteomics methodology (electrophoresis and mass spectrometry) is presented, and the proteome technique will be focused in the context of applications beneficial to the field of fish, shellfish and seafood/seafood product. In addition, the future potential application and challenge of proteomics in aquaculture will also be discussed.

Ecotoxicogenomics: Emerging Technologies for Emerging Contaminants1

Abstract: In recent years, new classes of aquatic pollutants have received attention from environmentalists, scientists, and regulators due to their introduction into the environment, unforeseen effects associated with the pollutants, or enhanced analytical techniques presently capable of detecting them. Many of these emerging contaminants are not well studied, making predictions regarding their toxicity to aquatic organisms or environmental fate difficult. Genomic technologies, including DNA microarrays, have been employed in many areas of biology to study disease states and the interaction of chemicals and nutrients with organisms. Here, we present the potential utility of DNA microarrays to address the challenges of emerging contaminants. DNA microarrays produce gene expression profiles creating an illustration of how a pollutant is acting within an exposed organism. Homology searches and online tools such as Gene Ontology can aid in the inferring a Mode of Toxicity, which may guide toxicity testing and risk characterization. Signature gene expression profiles offer the potential to uncover novel biomarkers of exposure and predict the presence of these contaminants in aquatic organisms. The No Observed Transcriptional Effect Level may play a role in determining if a predicted environmental concentration poses a risk to a sensitive species within an ecosystem. Additionally, DNA microarrays may add a complementary approach to Toxicity Identification Evaluations and help characterize causal agents in complex effluents.

Chemical Contamination of Aquatic Organisms from an Urbanized River in the New York/New Jersey Harbor Estuary

ABSTRACT The lower 6 miles of the tidal Passaic River, part of the New York/New Jersey (NY/NJ) Harbor Estuary system, are contaminated with a variety of organic and inorganic chemicals as a result of more than 150 years of heavy industrialization and urbanization. The River's ecology is substantially degraded due to habitat removal/alteration, and the organisms that reside in or utilize the River are exposed to and bioaccumulate chemicals from sediments and food web interactions. We quantify in this study the extent and magnitude of chemical contamination in several fish species (representing a range of trophic levels) and blue crab (Callinectes sapidus). In addition, the concentration of several contaminants of concern are compared to concentrations in similar organisms from other areas of the NY/NJ Harbor Estuary, as well as available tissue-based toxicological effects benchmarks that are reported in the literature. The results suggest that a variety of contaminants are present at elevated levels in each of the species collected from the River. Several contaminants, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), total DDT (2,2-bis[4-chlorophenyl]1,1-dichloroethene), copper, and mercury are present at average concentrations that exceed those from other waterways in the NY/NJ Harbor Estuary. However, the concentrations of contaminants in the River, with few exceptions do not exceed available toxic effects levels as reported in the literature for these or similar fish and crustaceans. This suggests that toxicological risks from bioaccumulative contaminants in the lower Passaic River are limited to select contaminants and species.

Distribution of Contaminants in Aquatic Organisms from East Fork Poplar Creek

The ecological risk assessment of East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee, investigated the nature and magnitude of the observed or expected adverse effects of the site's organic and inorganic contaminants on the ecosystem structure and function. Aquatic biota such as benthic macroinvertebrates, crayfish (Astacidae), redbreast sunfish (Lepomis auritus), and stonerollers (Campostoma anomalum), representative of various habitats, were sampled for whole-body contaminant analysis. The whole-body residue analysis of the representative aquatic organisms revealed the presence of over 50 contaminants in varying proportions. The relative whole-body distribution of organic contaminants such as mixtures of polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and pesticides was comparable among the indicator organisms. The relative whole-body distribution of inorganic contaminants was, however, less consistent. Physicochemical variables characteristic of organic contaminants—such as long octanol/water partition coefficient (logKow), log aqueous solubility, and log bioconcentration factors (log BCF), and chemical uptake efficiency (E) unique for the organisms sampled for chemical analysis—were used to explain the observed whole-body distribution of contaminants in the aquatic organisms from EFPC.

Mechanisms of bioaccumulation in aquatic systems.

Bioaccumulation of contaminants in aquatic organisms occur via several routes, including absorption across the cuticle and respiratory surfaces and assimilation from ingested media. For many contaminants of environmental importance, bioaccumulation can be understood as a simple partitioning process in which contaminants accumulate in living organisms in proportion to their lipophilicity. However, there are a variety of biological and physical factors that can influence bioaccumulation and result in deviations from the expected steady-state distribution of contaminants. Key variables have been identified, although their influence alone and in combination on bioaccumulation have yet to be determined. Because risk assessment depends on having an accurate evaluation of contaminant fate and effects, it is imperative to understand how bioaccumulation profiles may be modified by these variables.

Bioconcentration of chlorpyrifos by the three-spined stickleback under laboratory and field conditions

One of the aims of using kinetic models in aquatic toxicology is the prediction of residue levels of contaminants in aquatic organisms. However, only few investigations have compared residue levels observed in field tests to levels predicted through the use of laboratory-derived kinetic parameters. This paper investigates the feasibility of predicting the concentration of the organophosphorus insecticide chlorpyrifos in fish in outdoor mesocosms, using uptake and elimination rate constants determined in the laboratory. To this end three-spined sticklebacks were exposed to the insecticide in the laboratory and in three outdoor ditches. The lipid-based bioconcentration factor of chlorpyrifos in the sticklebacks was found to be (21 ± 4)·10 3 1 kg −1 in the laboratory. Uptake and elimination were succesfully described using a first-order one-compartment kinetic model. The lipid-based uptake and elimination rate coefficients were (26 ± 8)·10 3 1 kg −1 d −1 and 1.2 ± 0.4 d −1 respectively. The chlorpyrifos concentrations observed in sticklebacks which were taken from the mesocosms during the field study were found to be higher than calculated using the laboratory-derived toxicokinetic parameters. Discrepancies between expected and observed residues were similar for the two low-exposure ponds. The ratio between observed and expected residues was significantly higher in the third (high-exposure) ditch. It is concluded that the application of first-order one-compartment models, using laboratory-derived uptake and elimination rate coefficients, for the prediction of residues of chlorpyrifos in sticklebacks should be limited to concentrations far below the compounds LC50. Using the model at relatively high aqueous concentrations is likely to result in a significant underestimation of the residues in fish tissue.

Alternative tissue analysis method developed for organochlorine contaminants in aquatic organisms.

The exposure of aquatic life to organochlorine contaminants has been investigated during the past two decades because of human and ecosystem health concerns related to the bioaccumulation of hazardous, lipophilic substances. The toxic effects of polychlorodibenzo-p-dioxines and polychlorinated biphenyls (PCBs) are well known, and recent evidence also suggests that low level exposure to lipophilic organochlorines may interfere with normal development during sensitive early life history stages. As the use of lipophilic organochlorines, such as DDT, in third world countries continues and with the purported global cycling and food chain accumulation of persistent organochlorines, the occurrence of these compounds in aquatic organisms is a critical global environmental issue. An understanding of the fate of organochlorines in the environmental clearly remains an extremely important subject related to water quality. The U.S. Geological Survey (USGS) has recently gained congressional approval in the United States to track nation wide trends in water quality through the establishment of the National Water Quality Assessment Program (NAWQA). Among the goals defined by NAWQA, aquatic organisms, including fish, shellfish, and plants, collected from major drainage basins will be analyzed for, along with other contaminants, polychlorinated biphenyls (PCBs), organochlorine insecticides, and chlorobenzenes. The purpose of this report is tomore » present quality assurance data obtained from the development of a PCB, chlorobenzene, and organochlorine insecticide tissue analysis method in support of NAWQA and other large-scale water quality programs conducted through our laboratory. 12 refs., 1 fig., 2 tabs.« less

Role of FDA in establishing tolerable levels for dioxin and PCBS in aquatic organisms

When fishery products shipped in interstate commerce contain an environmental contaminant that presents a potential threat to public health, the Food and Drug Administration (FDA) undertakes appropriate regulatory steps to minimize exposure. These efforts range from seizure of the affected product to formal rule-making to establish a limit. The basic provision of the Food, Drug, and Cosmetic (FD&C) Act by which the agency deals with environmental contaminants in the food supply is section 402(a)(1), which deals with poisonous and deleterious substances. Poisonous and deleterious components are deemed to be "added," even if they are natural constituents of food, if any amount is present through the artifice of man. Furthermore, when the level of a naturally occurring toxin is increased in the food through handling and/or processing, the sum of all of the contaminant is deemed to be "added." Unavoidable environmental contaminants may be controlled and/or regulated under this section by the "may render injurious" standard, whereby the agency must demonstrate that there is a significant possibility that exposure to the contaminant could be injurious to human health. "Action levels" are administrative guidelines or instructions to the agency field units that define the extent of contamination at which the agency may regard food as adulterated. Except for polychlorinated biphenyls, for which there is a tolerance established by regulation, FDA has controlled contaminants in aquatic organisms by using action levels. Under section 406 of the FD&C act, the agency can also establish tolerances for unavoidably added poisonous or deleterious substances. This section allows the agency to consider the extent to which a contaminant is unavoidable in food while it limits exposure to the extent necessary to protect the public health. Section 406 requires that the tolerance be established by assessing several factors, including risk. One of these is the capability of processing technology to prevent, reduce, or otherwise control the level of the contaminant. Another factor is the necessity to avoid the needless removal of large amounts of valuable food from the market. Finally, the available analytical and sampling methods must be capable of measuring the contaminant so as to ensure the enforceability of the tolerance. Although the FDA has no statutory authority over intrastate fishing considerations, such as noncommercial fishing, it does provide advice to local or state authorities. It is the best scientific opinion the agency can give, but it is not enforceable per se. Advice is provided when requested by local and state officials where no guideline or tolerance is available, and is meant to deal with local and/or regional public health concerns.(ABSTRACT TRUNCATED AT 400 WORDS)