Aquatic Risk Research Articles

Aquatic Toxic Analysis by Monitoring Fish Behavior Using Computer Vision: A Recent Progress.

Video tracking based biological early warning system achieved a great progress with advanced computer vision and machine learning methods. Ability of video tracking of multiple biological organisms has been largely improved in recent years. Video based behavioral monitoring has become a common tool for acquiring quantified behavioral data for aquatic risk assessment. Investigation of behavioral responses under chemical and environmental stress has been boosted by rapidly developed machine learning and artificial intelligence. In this paper, we introduce the fundamental of video tracking and present the pioneer works in precise tracking of a group of individuals in 2D and 3D space. Technical and practical issues suffered in video tracking are explained. Subsequently, the toxic analysis based on fish behavioral data is summarized. Frequently used computational methods and machine learning are explained with their applications in aquatic toxicity detection and abnormal pattern analysis. Finally, advantages of recent developed deep learning approach in toxic prediction are presented.

A framework for ecological risk assessment of metal mixtures in aquatic systems.

Although metal mixture toxicity has been studied relatively intensely, there is no general consensus yet on how to incorporate metal mixture toxicity into aquatic risk assessment. We combined existing data on chronic metal mixture toxicity at the species level with species sensitivity distribution (SSD)-based in silico metal mixture risk predictions at the community level for mixtures of Ni, Zn, Cu, Cd, and Pb, to develop a tiered risk assessment scheme for metal mixtures in freshwater. Generally, independent action (IA) predicts chronic metal mixture toxicity at the species level most accurately, whereas concentration addition (CA) is the most conservative model. Mixture effects are noninteractive in 69% (IA) and 44% (CA) and antagonistic in 15% (IA) and 51% (CA) of the experiments, whereas synergisms are only observed in 15% (IA) and 5% (CA) of the experiments. At low effect sizes (∼ 10% mixture effect), CA overestimates metal mixture toxicity at the species level by 1.2-fold (i.e., the mixture interaction factor [MIF]; median). Species, metal presence, or number of metals does not significantly affect the MIF. To predict metal mixture risk at the community level, bioavailability-normalization procedures were combined with CA or IA using SSD techniques in 4 different methods, which were compared using environmental monitoring data of a European river basin (the Dommel, The Netherlands). We found that the simplest method, in which CA is directly applied to the SSD (CASSD ), is also the most conservative method. The CASSD has median margins of safety (MoS) of 1.1 and 1.2 respectively for binary mixtures compared with the theoretically more consistent methods of applying CA or IA to the dose-response curve of each species individually prior to estimating the fraction of affected species (CADRC or IADRC ). The MoS increases linearly with an increasing number of metals, up to 1.4 and 1.7 for quinary mixtures (median) compared with CADRC and IADRC , respectively. When our methods were applied to a geochemical baseline database (Forum of European Geological Surveys [FOREGS]), we found that CASSD yielded a considerable number of mixture risk predictions, even when metals were at background levels (8% of the water samples). In contrast, metal mixture risks predicted with the theoretically more consistent methods (e.g., IADRC ) were very limited under natural background metal concentrations (<1% of the water samples). Based on the combined evidence of chronic mixture toxicity predictions at the species level and evidence of in silico risk predictions at the community level, a tiered risk assessment scheme for evaluating metal mixture risks is presented, with CASSD functioning as a first, simple conservative tier. The more complex, but theoretically more consistent and most accurate method, IADRC , can be used in higher tier assessments. Alternatively, the conservatism of CASSD can be accounted for deterministically by incorporating the MoS and MIF in the scheme. Finally, specific guidance is also given related to specific issues, such as how to deal with nondetect data and complex mixtures that include so-called data-poor metals. Environ Toxicol Chem 2018;37:623-642. © 2017 SETAC.

Prospective aquatic risk assessment for chemical mixtures in agricultural landscapes.

Environmental risk assessment of chemical mixtures is challenging because of the multitude of possible combinations that may occur. Aquatic risk from chemical mixtures in an agricultural landscape was evaluated prospectively in 2 exposure scenario case studies: at field scale for a program of 13 plant‐protection products applied annually for 20 yr and at a watershed scale for a mixed land‐use scenario over 30 yr with 12 plant‐protection products and 2 veterinary pharmaceuticals used for beef cattle. Risk quotients were calculated from regulatory exposure models with typical real‐world use patterns and regulatory acceptable concentrations for individual chemicals. The results could differentiate situations when there was concern associated with single chemicals from those when concern was associated with a mixture (based on concentration addition) with no single chemical triggering concern. Potential mixture risk was identified on 0.02 to 7.07% of the total days modeled, depending on the scenario, the taxa, and whether considering acute or chronic risk. Taxa at risk were influenced by receiving water body characteristics along with chemical use profiles and associated properties. The present study demonstrates that a scenario‐based approach can be used to determine whether mixtures of chemicals pose risks over and above any identified using existing approaches for single chemicals, how often and to what magnitude, and ultimately which mixtures (and dominant chemicals) cause greatest concern. Environ Toxicol Chem 2018;37:674–689. © 2017 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Ecotoxicology Goes on a Chip: Embracing Miniaturized Bioanalysis in Aquatic Risk Assessment.

Biological and environmental sciences are, more than ever, becoming highly dependent on technological and multidisciplinary approaches that warrant advanced analytical capabilities. Microfluidic lab-on-a-chip technologies are perhaps one the most groundbreaking offshoots of bioengineering, enabling design of an entirely new generation of bioanalytical instrumentation. They represent a unique approach to combine microscale engineering and physics with specific biological questions, providing technological advances that allow for fundamentally new capabilities in the spatiotemporal analysis of molecules, cells, tissues, and even small metazoan organisms. While these miniaturized analytical technologies experience an explosive growth worldwide, with a substantial promise of a direct impact on biosciences, it seems that lab-on-a-chip systems have so far escaped the attention of aquatic ecotoxicologists. In this Critical Review, potential applications of the currently existing and emerging chip-based technologies for aquatic ecotoxicology and water quality monitoring are highlighted. We also offer suggestions on how aquatic ecotoxicology can benefit from adoption of microfluidic lab-on-a-chip devices for accelerated bioanalysis.

The Fate of Glyphosate and AMPA in a Freshwater Endorheic Basin: An Ecotoxicological Risk Assessment.

Glyphosate is the most widely used herbicide worldwide. However, there are some uncertain aspects with respect to its environmental fate. To evaluate the existence and distribution of this pesticide and its metabolite, aminomethylphosphonic acid (AMPA), their presence in fresh water, sediment, and suspended particulate matter (SPM) was measured in samples collected in a river running across a large city and through areas with intensive and extensive agriculture. The aquatic risk associated to the occurrence of these compounds was estimated using the hazard quotient (HQ) calculation for water and sediment. From the analyzed samples, overall 35% contained glyphosate, AMPA, or both compounds. Concentrations of the analytes were spread in different percentages depending on the environmental matrices considered, with levels ranging from 12 to 20 times higher for glyphosate and AMPA in sediment and SPM, as compared with the levels found in water. The most polluted area was situated within a green belt zone of the city; while in second place were sites located in areas of extensive agriculture. Aquatic organisms inhabiting areas both inside and outside agricultural areas are threatened by water glyphosate concentrations. Benthic organisms inside the greenbelt zone and inside the lower basin are threatened by the concentrations of glyphosate in sediment. Even when the concentrations measured in water were below the levels of concern for wildlife, results showed the risk of agricultural practices to aquatic biota. An update of the limits established for freshwater biota protection is needed.

Synthesis and application of a novel solid-phase extraction adsorbent for multiresidue analysis of insecticides in water.

A new solid-phase adsorbent was synthesized for the simultaneous enrichment of multiple classes of trace insecticides (neonicotinoids, organophosphates, fiproles, and organochlorines) in water. The adsorbent was spherical with a diameter, surface area, average pore volume, and pore size of approximately 5μm, 341m2 /g, 0.092m3 /g, and 2.22nm, respectively. Extraction conditions were optimized, including water pH and the type and volume of the rinsing and eluting solvents. After extraction, target insecticides were analyzed by gas chromatography with mass spectrometry and high-performance liquid chromatography with tandem mass spectrometry. The recovery of neonicotinoids ranged from 63.0 to 124%, except for clothianidin (40.1-52.9%). Recoveries of organophosphates, fiproles, and organochlorines were in the ranges of 37.0-102, 64.0-101, and 42.0-69.3%, respectively. Relative standard deviations were<20% except for profenofos (5.1-30%) and method detection limits were 1.8-12.7ng/L, suggesting that the precision and accuracy of the developed method were viable. At environmentally relevant concentrations, the new adsorbent achieved comparable recoveries of target insecticides to hydrophilic-lipophilic balance adsorbent while providing an additional advantage by further reducing matrix effects. Field water samples from the Pearl River in Guangzhou, China were analyzed, and the frequent detection of neonicotinoids raises concerns about their aquatic risk.

Identifying potential gaps in pesticide risk assessment: Terrestrial life stages of freshwater insects

Abstract Insecticides are important drivers of biodiversity loss and ecological impairment in freshwater ecosystems. Freshwater insects may be exposed to insecticides via water during larval/nymph stages and via air, habitats, and food during adult stages in the terrestrial environment. The aquatic risk assessment (RA) of pesticides does not consider terrestrial life stages, and a literature review revealed that pesticide ecotoxicity data for adult freshwater insects are very scarce and outdated. Consequently, it is not possible to assess how adult freshwater insects may be protected through RA programs for terrestrial non‐target organisms. We give guidance to generating and using of such ecotoxicity data focusing on species selection, test design and type of ecotoxicity information. Policy implications. This commentary considers how terrestrial stages of aquatic insects are protected by pesticide risk assessment (RA) and highlights the necessity of performing holistic risk assessment, focusing on organisms and populations as supplement to current subdivisions in element‐based compartments (e.g. aquatic and terrestrial ecosystems).

Environmental fate of amine oxide: Using measured and predicted values to determine aquatic exposure

Amine oxide (AO) surfactants are used widely in North American household detergents resulting in >44,000mtons disposed down the drain annually. Due to AOs substantial down the drain disposal volume, wide dispersive use, and high aquatic toxicity, there is a need to evaluate ecological exposure and corresponding risk. This study refined the current knowledge regarding the fate of AO disposed down the drain through laboratory simulation studies to evaluate biodegradation in the sewer and during activated sludge wastewater treatment. A monitoring program which measured effluent AO concentrations for the dominant carbon chain lengths, C12 and C14, at 44 wastewater treatment plants (WWTP) across the continental US was also conducted. The study results were then used as input into probabilistic exposure models to predict US receiving stream concentrations. In three separate OECD 314A Sewer Water Die-Away studies AO was rapidly biodegraded with >76% mineralized by study completion and the geometric mean of the primary biodegradation rates being 0.184h−1. Two OECD 303A Activated Sludge WWTP Simulation studies showed rapid and complete biodegradation of AO with ≤0.09% of parent AO remaining in the effluent, ≤0.03% of parent AO sorbed to sludge solids, and >97% complete mineralization of AO. Monitoring at US WWPTs confirmed low levels of AO in effluents with mean C12 and C14AO concentrations of 52.8 and 20.1ng/L respectively. Based on the monitoring data, the 90th percentile concentrations of C12 and C14AO for 7Q10 low flow stream conditions were >2 orders of magnitude lower than the predicted no effect concentrations indicating negligible aquatic risk from AO in US receiving streams. This study verifies that AO is safe for the aquatic environment even at the currently high usage volumes due to rapid biodegradation during transit through the sewer and wastewater treatment.

Ecological risk estimation of organophosphorus pesticides in riverine ecosystems

Pesticides are of great concern because of their existence in ecosystems at trace concentrations. Worldwide pesticide use and its ecological impacts (i.e., altered environmental distribution and toxicity of pesticides) have increased over time. Exposure and toxicity studies are vital for reducing the extent of pesticide exposure and risk to the environment and humans. Regional regulatory actions may be less relevant in some regions because the contamination and distribution of pesticides vary across regions and countries. The risk quotient (RQ) method was applied to assess the potential risk of organophosphorus pesticides (OPPs), primarily focusing on riverine ecosystems. Using the available ecotoxicity data, aquatic risks from OPPs (diazinon and chlorpyrifos) in the surface water of the Langat River, Selangor, Malaysia were evaluated based on general (RQm) and worst-case (RQex) scenarios. Since the ecotoxicity of quinalphos has not been well established, quinalphos was excluded from the risk assessment. The calculated RQs indicate medium risk (RQm = 0.17 and RQex = 0.66; 0.1 ≤ RQ < 1) of overall diazinon. The overall chlorpyrifos exposure was observed at high risk (RQ ≥ 1) based on RQm and RQex at 1.44 and 4.83, respectively. A contradictory trend of RQs > 1 (high risk) was observed for both the general and worst cases of chlorpyrifos, but only for the worst cases of diazinon at all sites from downstream to upstream regions. Thus, chlorpyrifos posed a higher risk than diazinon along the Langat River, suggesting that organisms and humans could be exposed to potentially high levels of OPPs.

The power of hybrid modelling: An example from aquatic ecosystems

Planktonic communities in ponds and lakes show a high annual dynamic controlled by biotic interactions, nutrients and weather. In recent years, there has been an increase in demand for realistic and accurate lake models to improve ecological management of water bodies and to answer ecotoxicological questions in aquatic risk assessment. Most existing aquatic models are either ecosystem models aimed at describing the overall ecosystem dynamics, but which are incapable of including individual life-cycles and plasticity, or very detailed and realistic individual-based models lacking an appropriate level of environmental complexity. To reconcile these concepts, we present here a modelling approach using an individual-based population model (IBM), integrated within an ecosystem lake model, to link responses at the individual and population levels. We combine an IBM for Daphnia magna (IDamP) and a complex biogeochemical lake model (StoLaM), to create the DaLaM (Daphnia Lake Model). We use DaLaM to predict population dynamics of D. magna and phytoplankton within a simplified, daphnid-dominated food web under field conditions. In DaLaM, relevant variable environmental conditions such as underwater light climate, water temperature, turbulence, and nutrient availability are realistically simulated forced by weather conditions. For model testing we used data from aquatic mesocosm field studies exhibiting variable nutrient and weather conditions and lasting from several months to 2 years. DaLaM gave improved predictions of the overall population patterns of daphnids and phytoplankton in the mesocosms in contrast to its separate submodels. This study is an example of successfully merging individual-based population models with dynamic ecosystem models utilising the accuracy of the former and the dynamic environment of the latter to simulate more realistic field populations.

Multigenerational effects of triclosan on the demography of Plationus patulus and Brachionus havanaensis (ROTIFERA)

Triclosan is a personal care product widely used in North America, Europe and Asia as antimicrobial ingredient in many consumer chemical products. In Mexico concentrations of triclosan have been reported in aquatic systems. However, there is no law regulating the presence of chemicals such as triclosan, in aquatic systems. The scarce data about this chemical has increased concern among ecotoxicologists regarding possible effects on aquatic organisms. Moreover, multigenerational studies are rarely studied and the results vary depending on the contaminant. Rotifers, are a dominant group of zooplankton, and have been used in aquatic risk assessments of personal care products due to their sensitivity and high reproductive rates. Plationus patulus and Brachionus havanaensis are common rotifers distributed in aquatic ecosystems of Mexico and have been used in ecotoxicological bioassays. In this study, the median lethal concentration (LC50, 24h) of P. patulus and B. havanaensis exposed to triclosan was determined. Based on the LC50, we tested three sublethal concentrations of triclosan to quantify the demographic responses of both rotifers for two successive generations (F0, and F1). The 24h LC50 of triclosan for P. patulus and B. havanaensis were 300 and 500µgL−1 respectively. Despite the concentration, triclosan had an adverse effect on both Plationus patulus and Brachionus havanaensis in both generations exposed. Experiments show that P. patulus was more sensitive than B. havanaensis when exposed to triclosan. When exposed to triclosan the parental generation (F0) of P. patulus was far more affected than F1.

Single and mixture toxicity of abamectin and difenoconazole to adult zebrafish (Danio rerio)

Concerns have been raised in recent years on the potential risks related with pesticide mixtures that are likely to be present in agricultural edge-of-field waterbodies. Despite the high use of pesticides in tropical countries like Brazil, studies evaluating pesticide mixtures are especially scarce in the tropics. The insecticide abamectin and the fungicide difenoconazole are the main pesticides intensively used in Brazilian strawberry crop and are hence likely to occur simultaneously. The aim of the present study was therefore to evaluate the toxicity of abamectin, difenoconazole and their mixture to the tropical fish Danio rerio. Laboratory toxicity tests with the individual pesticides indicated 48 h-LC50 values of 59 μg L−1 for abamectin and 1.4 mg L−1 for difenoconazole. Mixtures of the two pesticides revealed a synergistic deviation of the independent action model. Implications of study findings for the aquatic risk assessment of pesticide mixtures, especially in tropical countries and indications for future research are discussed.

Structural and functional effects of a short-term pyrethroid pulse exposure on invertebrates in outdoor stream mesocosms

Agricultural land-use frequently results in short pulse exposures of insecticides such as pyrethroids in river systems, adversely affecting local invertebrate communities. In order to assess insecticide-induced effects, stream mesocosms are used within higher tier aquatic risk assessment. Regulatory acceptable concentrations (RACs) derived from those studies are often higher compared with tier 1 RACs. Hence, the present mesocosm study evaluates this aspect using a pulse exposure scenario typical for streams and the pyrethroid insecticide etofenprox. A 6-h pulse exposure with measured concentrations of 0.04, 0.3 and 5.3μgL−1 etofenprox was used. We considered abundance, drift and emergence of invertebrates as structural endpoints and the in situ-measured feeding rates of the isopod Asellus aquaticus as functional endpoint. Most prominent effects were visible at 5.3μgL−1 etofenprox which caused adverse effects of up to 100% at the individual and population level, as well as community structure alterations. Transient effects were observed for invertebrate drift (effect duration ≤24h) and for the invertebrate community (9 days after exposure) at 0.3μgL−1 etofenprox. Furthermore, 0.04μgL−1 etofenprox affected the abundance of the mayfly Cloeon simile (decrease by 66%) and the feeding rate of A. aquaticus (decrease by 44%). Thus, implications for the functional endpoint leaf litter breakdown in heterotrophic ecosystems may be expected. A hypothetical RAC derived from the present mesocosm study (0.004μgL−1) is in line with the official tier 1 RAC (0.0044μgL−1) and thus shows that the present mesocosm study did not result in a higher RAC.

English

There is evidence that ammonia, hydrogen sulphide and dissolved oxygen are implicated in fish kills occurring on the Lake Malawi shores of Karonga town. Exposure to fish is influenced by strong winds while water temperature differences cause upwelling and fish mortalities in surface waters. The vulnerability of fish in Karonga town to physico-chemical factors was computed from secondary sources data obtained in 2000 to 2016 regarding lethal and sub-lethal limits; this has helped to broaden our understanding of aquatic risk factors in this area. Equilibria relationships of ammonia (NH3 + H2O = NH4+ + OH-; K = 10-4.74; 2.70-4.28 &micro;g.L-1 at depth of 100 to 200 m) and hydrogen sulphide (H2S = HS- + H+; K= 10-7.01; 54.9-82.5 mg.L-1 at a depth of 0-150 m) are imputed to have been implicated in the cause of a spate of fish kills.&nbsp; Uranium fallout might also be implicated but further analysis on actual exposure is needed to confirm this. Inferences of fish vulnerability have been drawn from studies done elsewhere on similar freshwater fish but under controlled conditions. While fish catches temporarily improved in 2007-2008 and 2010-2011, changes in fish diversity have been consistent, such as the disappearance of Ntchila (Labeo mesops), decline of Chambo (Oreochromis species) and the dominance of sardine type Usipa (Engraulicyprus sardella). Therefore, other sources of risks are over-fishing and climate change; the latter is evidenced by warming of the deep water columns, reduced dissolved oxygen and declining Lake Malawi water levels. The significance of fish by-catch recorded as &lsquo;others&rsquo; indicates that a high number of fish species remain scientifically undescribed, hence the need for further taxonomic studies. Fish catches as per caput fish supply for Karonga District (19.5-38 kg) are above the current national average of 4.0 go 5.8 kg. Since fish provides Karonga communities with affordable animal protein, it significantly contributes to food security for the town. More than 5,500 people depend directly on fishing, representing 10% of the population of Karonga. Fisheries are a driver to rural commercialization for businesses of up to 22,000 people; hence, it is critical to people&rsquo;s livelihoods and incomes at the local level. Therefore, this study confirms what has commonly been observed for Karaonga town; that fish as a nutrition and income source should be factored into studies dealing with risks to livelihoods of Karonga town communities; even where this might require indirect methods of assessment. Key words: Fish catches, Karonga town, Lake Malawi, fish diversity, per caput fish supply, thermodynamic concentrations (H2S/HS-; NH3/NH4+).

Aquatic Fate of Aerially Applied Hexazinone and Terbuthylazine in a New Zealand Planted Forest

Herbicides are used to control competing vegetation during tree establishment, and are often critical to the productivity and economic viability of a planted forest crop. Despite increasing public concern over herbicide use in planted forests and potential impact on the environment, there is limited information on the aquatic fate of many of these herbicides when applied in forests according to standard operational procedures. Two herbicides commonly used in New Zealand’s planted forests, terbuthylazine and hexazinone, were aerially applied during two consecutive years at 7.4 kg and 1.1 kg ha-1 respectively, to a 12.5 ha catchment of newly planted Pinus radiata (Radiata pine) in the Bay of Plenty region of New Zealand. One hundred percent of the area was sprayed during Year 1 while 85% of the area was sprayed during Year 2. The highest concentrations of both herbicides were measured in stream water, sediment and algal samples on the day of herbicide application during Year 1 (September 2012 to June 2013), mainly as a result of spray drift, and in stream water during Year 2 (September 2013 to April 2014) at the time of a rainfall event seven days after herbicide application. Terbuthylazine concentrations exceeded New Zealand and World Health Organisation drinking water standards for &lt;24 hours on both occasions. For the remainder of the trial period, concentrations of both herbicides were below safe drinking water standards. Herbicide concentrations in stream flow declined immediately below the trial site and were close to or below detection limits at the bottom of the catchment. The concentrations of terbuthylazine and hexazinone in stream flow during this trial, posed a short-term and low risk to algae. Peak concentrations of both herbicides were several orders of magnitude lower than Lethal Concentration (LC)50 concentrations for Daphnia and rainbow trout (Oncorhynchus mykiss). These results highlight the need to include data from both field and laboratory based trials when assessing the aquatic risk of these two herbicides when applied under operational conditions in planted forests.

Laboratory- and full-scale studies on the removal of pharmaceuticals in an aerated constructed wetland: effects of aeration and hydraulic retention time on the removal efficiency and assessment of the aquatic risk.

Pharmaceutical residues in wastewater pose a challenge to wastewater treatment technologies. Constructed wetlands (CWs) are common wastewater treatment systems in rural areas and they discharge often in small water courses in which the ecology can be adversely affected by the discharged pharmaceuticals. Hence, there is a need for studies aiming to improve the removal of pharmaceuticals in CWs. In this study, the performance of a full-scale aerated sub-surface flow hybrid CW treating wastewater from a healthcare facility was studied in terms of common water parameters and pharmaceutical removal. In addition, a preliminary aquatic risk assessment based on hazard quotients was performed to estimate the likelihood of adverse effects on aquatic organisms in the forest creek where this CW discharges. The (combined) effect of aeration and hydraulic retention time (HRT) was evaluated in a laboratory-scale batch experiment. Excellent removal of the targeted pharmaceuticals was obtained in the full-scale CW (>90%) and, as a result, the aquatic risk was estimated low. The removal efficiency of only a few of the targeted pharmaceuticals was found to be dependent on the applied aeration (namely gabapentin, metformin and sotalol). Longer and the HRT increased the removal of carbamazepine, diclofenac and tramadol.

Evaluation of triclosan in Minnesota lakes and rivers: Part I – ecological risk assessment

Triclosan, an antimicrobial compound found in consumer products, may be introduced into the aquatic environment via residual concentrations in municipal wastewater treatment effluent. We conducted an aquatic risk assessment that incorporated the available measured triclosan data from Minnesota lakes and rivers. Although only data reported from Minnesota were considered in the risk assessment, the developed toxicity benchmarks can be applied to other environments. The data were evaluated using a series of environmental fate models to ensure the data were internally consistent and to fill any data gaps. Triclosan was not detected in over 75% of the 567 surface water and sediment samples. Measured environmental data were used to model the predicted environmental exposures to triclosan in surface water, surface sediment, and biota tissues. Toxicity benchmarks based on fatty acid synthesis inhibition and narcosis were determined for aquatic organisms based, in part, on a species sensitivity distribution of chronic toxicity thresholds from the available literature. Predicted and measured environmental concentrations for surface water, sediment, and tissue were below the effects benchmarks, indicating that exposure to triclosan in Minnesota lakes and rivers would not pose an unacceptable risk to aquatic organisms.

Application of Box–Behnken design to optimize multi-sorbent solid phase extraction for trace neonicotinoids in water containing high level of matrix substances

Extensive use of neonicotinoid insecticides has raised great concerns about their ecological risk. A reliable method to measure trace neonicotinoids in complicated aquatic environment is a premise for assessing their aquatic risk. To effectively remove matrix interfering substances from field water samples before instrumental analysis with HPLC/MS/MS, a multi-sorbent solid phase extraction method was developed using Box-Behnken design. The optimized method employed 200mg HLB/GCB (w/w, 8/2) as the sorbents and 6mL of 20% acetone in acetonitrile as the elution solution. The method was applied for measuring neonicotinoids in water at a wide range of concentrations (0.03–100μg/L) containing various amounts of matrix components. The recoveries of acetamiprid, imidacloprid, thiacloprid and thiamethoxam from the spiked samples ranged from 76.3% to 107% while clothianidin and dinotefuran had relatively lower recoveries. The recoveries of neonicotinoids in water with various amounts of matrix interfering substances were comparable and the matrix removal rates were approximately 50%. The method was sensitive with method detection limits in the range of 1.8–6.8ng/L for all target neonicotinoids. Finally, the developed method was validated by measurement of trace neonicotinoids in natural water.

An Evaluation of Molybdenum Toxicity to the Oligochaete, Tubifex tubifex, and Early-Life Stages of Brown Trout, Salmo trutta.

Limited data are available describing the aquatic toxicity of molybdenum in freshwater environments, making it difficult to assess the aquatic risk to freshwater organisms. In order to increase available information on the aquatic toxicity of molybdenum, a 96-h LC50 test with the oligochaete Tubifex tubifex and an 85-day development test using brown trout, Salmo trutta, were conducted. The T. tubifex test resulted in an LC50 value of 2782mg/L. No adverse effects were observed on brown trout survival or length in the concentrations tested, however an IC10 value for growth (wet weight) was determined to be 202mg/L. Whole body fish tissue concentrations for molybdenum increased in all treatment concentrations tested, although bioconcentration factors decreased at greater exposure concentrations, and ranged from 0.13 at an exposure concentration of 20mg/L to 0.04 at an exposure of 1247mg/L. A body burden of 26.0mg/kg was associated with reduced wet weight.

The development of cellular immune defence in marine medaka Oryzias melastigma

Environmentally induced alterations of the immune system during sensitive developmental stages may manifest as abnormalities in immune organ configuration and/or immune cell differentiation. These not only render the early life stages more vulnerable to pathogens, but may also affect the adult immune competence. Knowledge of these sensitive periods in fish would provide an important prognostic/diagnostic tool for aquatic risk assessment of immunotoxicants. The marine medaka Oryzias melastigma is an emerging seawater fish model for immunotoxicology. Here, the presence and onset of four potentially sensitive periods during the development of innate and adaptive cellular immune defence were revealed in O. melastigma: 1.) initiation of phagocyte differentiation, 2.) migration and expansion of lymphoid progenitor cells, 3.) colonization of immune organs through lymphocyte progenitors and 4.) establishment of immune competence in the thymus. By using an established bacterial resistance assay for O. melastigma, larval immune competence (from newly hatched 1dph to 14dph) was found concomitantly increased with advanced thymus development and the presence of mature T-lymphocytes. A comparison between the marine O. melastigma and the freshwater counterpart Oryzias latipes disclosed a disparity in the T-lymphocyte maturation pattern, resulting in differences in the length of T-lymphocyte maturation. The results shed light on a potential difference between seawater and freshwater medaka in their sensitivity to environmental immunotoxicants. Further, medaka immune system development was compared and contrasted to economically important fish. The present study has provided a strong scientific basis for advanced investigation of critical windows for immune system development in fish.