Lowest Observed Effect Concentration Values Research Articles

Anodonta cygnea, a freshwater swan mussel, exposed to diazinon: toxicity thresholds in behaviour and physiology.

Swan mussels (Anodonta cygnea) have been suggested as suitable bioindicators for the presence of pollutants in the environment. Application of the physiological and behavioral markers in these sessile species can be beneficial for environmental monitoring. The present study aimed to investigate the relationship between the behavioral disorders of movement and siphoning associated with the inhibition of tissue Acetylcholinesterase (AChE). For experiments, overally 120 bivalves of Anodonta cygnea (mean total length 80.33 ± 6.7mm) were transported from the agricultural drains and canals in Sari county (Mazandaran Province, Iran) to our laboratory. First, the LC50-96h of diazinon was estimated according to the Organization for Economic Co-operation and Development (OECD1992) guideline with static water conditions. The sub-lethal toxicity pesticide experiments were conducted on the basis of the lowest observed effect concentration (LOEC) and the maximum acceptable toxicant concentration (MATC). The LC50-96h, LOEC, and MATC values of diazinon were 85.2, 42.1, and 8.5mg L- 1, respectively. Based on the observations of mussels' movement, the burrowing and displacement decreased with the concentration of toxicant in water. Moreover, the presence of diazinon in water and its exposure to experimental animals significantly reduces their siphoning rate. The RDA showed that the AChE activity had a higher correlation with the siphoning behavior than the movement behavior. The comparison of enzyme activity at different exposure and recovery times showed that there was a significant difference among the groups affected by the consumed pesticide (p = 0.001, between contrasts). The most remarkable morphometric characteristic was the siphon opening that was inversely correlated with the enzymatic activity. Studies in bioethics might benefit from paying attention to these traits that are directly related to the level of toxicity and behavioral adaptations required for animal survival.

Are the Brazilian prevention values for copper and zinc in soils suitable for protecting earthworms against metal toxicity?

The current Brazilian copper (Cu) and zinc (Zn) prevention values (PV) for soil quality do not take into account the ecotoxicological impacts on soil organisms, which suggests these guiding values may not be protective of soil ecological trophic levels. This study assessed the acute (mortality) and chronic toxicity (reproduction), as well as the cumulative (bioaccumulation) potential of Cu and Zn (pseudo-total and available fractions) for earthworms Eisenia andrei in a Tropical Artificial Soil (TAS) and two tropical field soils (Oxisol and Alfisol). Toxicity data based on pseudo-total fractions were compared to PV. The Lowest Observed Effect Concentrations (LOEC) for the mortality endpoint were found at Cu and Zn concentrations higher than their PV (60 and 300mgkg-1, respectively), regardless of the soil type. However, concentrations lower than PV reduced the reproduction of E. andrei by 20% (compared to the controls) for Cu in all tested soils (EC20s from 31.7 to 51.2mgkg-1) and by 50% for Zn in Oxisol and Alfisol (EC50s = 225 and 283mgkg-1, respectively). In TAS, only the EC20 (273mgkg-1) for Zn was lower than PV. Increases of Cu in earthworm tissues occurred at concentrations higher than PV in all tested soils (LOEC values from 70 to 107mgkg-1). The same was observed for Zn in TAS (LOEC = 497mgkg-1), while in the field soils, the increases of Zn in earthworm tissues were lower than PV (LOEC = 131 and 259mgkg-1 in Alfisol and Oxisol, respectively). We suggest the following: (1) The current Brazilian PV for Cu and Zn are not protective for earthworms (E. andrei) in the field soils tested; (2) PV derived from ecotoxicological assays in artificial soil cannot be representative for Brazilian field soils; (3) Using PV based on the pseudo-total fraction, without a soil-type normalizing factor, may limit the representativeness of this threshold for different soil types.

Linking environmental exposure and effects of pharmaceuticals on aquatic biota: state of knowledge in Latin America

The presence of pharmaceutically active compounds (PhACs) in the environment has been confirmed in different parts of the world, but mainly in North America and Europe. In Latin America, progress on this issue has not been as advanced, so we decided to compile the available information. The aim was to relate the environmental exposure of PhACs detected in fresh surface waters of Latin America, their bioaccumulation and lethal or sublethal effects. Most of the reported concentrations are in the same order of magnitude (113 PhACs in fresh surface water: 0.04-227,000 ng/L, 57 PhACs in aquatic biota: 0.02-652 ng/g d.w.) as those previously reported worldwide. The groups with the highest concentrations were analgesics/anti-inflammatories in water and antibiotics in biofilm. For effects, we found 67 no observed effect concentration (NOEC) values for 37 PhACs, 36 lowest observed effect concentration (LOEC) values for 26 PhACs and 45 lethal concentration (LC50) values for 31 PhACs. The only compound whose concentration in water exceeded the lowest LC50 value was acetaminophen (32,000 ng/L), which is an alarm signal for the need for further monitoring of this PhAC. In addition, acetaminophen, caffeine, carbamazepine, propranolol, 17α-ethinylestradiol and 17β-estradiol were the only PhACs with NOEC and LOEC values below the concentration in water. At the regional level, the information available in Latin America is scarce and becomes even scarcer when bioaccumulation in aquatic biota is considered. At the global level, little ecotoxicological information is available. This review identifies knowledge gaps and serves as a guide and reference for further decision-making.

Assessment of Acute and Short-Term Developmental Toxicity of Mercury Chloride to Rare Minnow (Gobiocypris rarus)

Mercury (Hg), as the most potentially hazardous heavy metal, has accumulated in the aquatic environment and has caused concern about its safety. To test the toxic effects of mercury chloride (Hg2+) on rare minnow (Gobiocypris rarus), the acute toxicity of Hg2+ to embryos, newly hatched larvae, juvenile fish, and the short-term developmental toxicity of Hg2+ to the embryo and sac-fry stages, were investigated. The 96-h LC50 values of Hg2+ to embryos, newly hatched larvae, and juvenile fish were 0.56, 0.07, and 0.10 mg/L, respectively, suggesting newly hatched larvae were the most sensitive, followed by juvenile fish, while embryos were the most resistant in response to an Hg2+ challenge. The research data revealed that the safe level of Hg2+ exposure for rare minnow was 0.7 μg/L. In addition, the LOEC (lowest observed effect concentration) and NOEC (no observed effect concentration) values of Hg2+ to heartbeat, mortality, malformation rate, and body length of survived larvae were identically, 0.05 and 0.01 mg/L, respectively. These findings indicated that Hg2+ had lethal effects on rare minnow at different life stages, and that newly hatched larvae were the most sensitive stage. The above findings have important implications for better understanding the environmental risk assessment of Hg2+ on aquatic organisms.

Acute Toxicity of NH4Cl to Tambra Fish (Tor Tambroides) Fry

Ammonia is one of the nutrient wastes products which can be toxic to all vertebrates, including fish. Usually, ammonia toxicity is expressed as Total Ammonia Nitrogen (TAN, mgN/L). Tambra fish (Tor tambroides) is freshwater fish with important economic value in some areas in Indonesia. According to overfishing and forest degradation, the fish has become threatened. This research aimed to calculate the LC50 value of ammonia to Tambra fish (Tor tambroides) and estimate NOEC, LOEC, and MATC values of ammonia to Tambra fish (Tor tambroides). This study was conducted using the static test method with two steps. The first stage is a preliminary test, where the preliminary test is observed for 24 hours With five concentrations excluding control. Whereas in the second stage that is carried out, observation for 96 hours with four concentrations excluding control. The Probit test is Performed to obtain LC50 value results, then proceed with ammonia analysis using the Salicylate Test Kit method. The results showed that ammonia had acute toxicity with LC50-96 hour value of NH4Cl against Tambra fish fry (Tor tambroides) in the amount of 354.615 mg/L. Ammonia caused acute toxicity to Tambra fish fry (Tor tambroides).The LC50-96 hour value was 354.615 mg/L in the form of Total Ammonia Nitrogen (TAN) or it was equivalent to un-ionized Ammonia (NH3) of 9.8937 mg/L, while values of the Lowest Observed Effect Concentration (LOEC) and No Observed Effect Concentration (NOEC) of ammonia on Tambra fish (Tor tambroides) were 578.24 mg/L and 280.18 mg/L, respectively.

Phyto-Synthesized Silver Nanoparticle Toxicity Effect on Aquatic Plant Lemna minor L.

Silver nanoparticles (AgNP) are made up about 55% of all nanomaterials produced and are widely used in consumer products. Its is inevitable that these particles are released to the aquatic environment during production, use and disposal. In this study, subacute toxicity of AgNPs obtained by phyto-synthesis was investigated on Lemna minor L. (duckweed) plants. Plant stock cultures were grown in the climate room according to OECD 221 guidelines. After 8 weeks of acclimation, the plants were treated with AgNP concentrations ranging from 0.005 to 50 mg L−1 for 7- and 14-days. The formation of silver nanoparticles obtained from laurel (Laurus nobilis L.) extract was determined by UV-VIS spectrophotometric measurements. The AgNPs synthesized by the phyto-synthesis method were characterized by Fourier transform infrared spectroscopy (FT-IR), Zeta size and potential, Inductively Coupled Plasma Mass Spectrometry and Scanning electron microscopy (SEM-EDS) analysis. The analysis results show that AgNPs are homogeneously distributed, spherical in shape with an average size of 34 nm and coated with phyto-content. The increase in AgNP concentration caused a decrease in frond numbers. Growth inhibition data showed that the EC50 value of phyto-synthesized AgNP was 4.78 mg L-1 and the lowest observed effect concentration (LOEC) was 0.5 mg L-1 for 7-days. AgNP concentrations below LOEC level (0.05, to 0.5 mg L-1) caused a significant decrease in growth rate by 20.07% after 7 days of exposure while it was found 4.03% for 14-days treatment at the highest AgNP concentration (0.5 mg L-1). Similar trend was observed in fresh-and dry weight of plants indicating prolonged exposure time triggering tolerance mechanism which was corroborated by chlorophyll a/b and carotenoids content results. Based on higher NOEC, LOEC and EC50 values, phyto-synthesized AgNP usage may lead less environmental toxicity.

Risk of chlorine dioxide as emerging contaminant during SARS-CoV-2 pandemic: enzyme, cardiac, and behavior effects on amphibian tadpoles

ObjectiveThe use of chlorine dioxide (ClO2) increased in the last year to prevent SARS-CoV-2 infection due to its use as disinfectant and therapeutic human treatments against viral infections. The absence of toxicological studies and sanitary regulation of this contaminant represents a serious threat to human and environmental health worldwide. The aim of this study was to evaluate the acute toxicity and sublethal effects of ClO2 on tadpoles of Trachycephalus typhonius, which is a common bioindicator species of contamination from aquatic ecosystems.Materials and methodsMedian lethal concentration (LC50), the lowest-observed effect concentration (LOEC), and the no-observed effect concentration (NOEC) were performed. Acetylcholinesterase (AChE) and glutathione-S-transferase (GST) activities, swimming behavior parameters, and cardiac rhythm were estimated on tadpoles of concentrations ≤ LOEC exposed at 24 and 96 h. ANOVA and Dunnett’s post-hoc comparisons were performed to define treatments significance (p ≤ 0.05).ResultsThe LC50 of ClO2 was 4.17 mg L−1 (confidence limits: 3.73–4.66). In addition, NOEC and LOEC values were 1.56 and 3.12 mg L−1 ClO2, respectively, at 48 h. AChE and GST activities, swimming parameters, and heart rates increased in sublethal exposure of ClO2 (0.78–1.56 mg L−1) at 24 h. However, both enzyme activities and swimming parameters decreased, whereas heart rates increased at 96 h.ConclusionOverall, this study determined that sublethal concentrations of ClO2 produced alterations on antioxidant systems, neurotoxicity reflected on swimming performances, and variations in cardiac rhythm on treated tadpoles. Thus, our findings highlighted the need for urgent monitoring of this chemical in the aquatic ecosystems.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s13530-021-00116-3.

Survival and Reproductive Effects in the Aquatic Invertebrate Ceriodaphnia dubia Exposed to Uranium Spiked Site Water Collected from Two Creeks in the Yukon, Canada.

This study evaluates aqueous uranium (U) toxicity in Ceriodaphnia dubia exposed to surface water collected from two creeks located in U-rich areas of Yukon, Canada. Water for toxicity testing was collected at two times of the year to represent water quality characteristics generally observed during open-water (high flows) and winter baseflow water (low flows) seasons. Collected water was transferred to the toxicological laboratory and spiked with U to achieve nominal concentrations of 50, 150, 350, 500, 650, 800, and 1000µgU/L. Toxicity endpoints included lethal concentrations (LC50) for survival, in addition to no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) for reproduction. All derived toxicity endpoints were significantly higher than applicable Canadian water-quality guidelines for U (15μg/L [Chronic] and 33μg/L [Acute]). No effects on C. dubia survival were observed at LC50 concentrations > 799μgU/L. Derived NOEC (381μgU/L) and LOEC (524μgU/L) values also were significantly above chronic water quality guidelines. The differences noted in the toxicity response between seasons were mainly due to the presence of toxicity ameliorating factors for U (i.e., dissolved organic carbon). These results highlight the high conservatism in applicable water-quality guidelines and the crucial need to consider site-specific water characteristics when deriving environmentally relevant, yet protective thresholds for uranium in aquatic environments.

제브라피쉬 초기배아발생단계의 기형현상을 이용한 만성 NOEC의 예측방법 개발

This study has developed a new simplicity toxicity assessment method that can predict the chronic NOEC (No Observed Effect Concentration) value rapidly by observing the morphological abnormality at the low concentration area in the early embryonic development stage of Danio rerio. As a result, the acute LOEC (Lowest Observed Effect Concentration) values of Camptothecin, Camphor and Curcumin were calculated as 9.3 nM, 1248.4 μM and 18.3 μM, respectively. The morphological anomalies were observed to yolk sac edema (YSE), pericardial edema (PE), black yolk (BY), bent spine (BS), albinism (A), dyed yellow yolk (DY), collapse symptoms of fertilized embryo tissue (CPFE), no heartbeat (NHB), reduced heart rate (RHR), hatching delay (HD), short body length (SBL). And acute NOEC values were classified into A-type and B-type depending on the presence or absence of morphological anomalies. A-type morphological anomalies were observed at 6.2 nM, 832.3 μM and 9.2 μM, similar to the area near acute LOEC except for albinism (A), dyed yellow yolk (DY), collapse symptoms of fertilized embryo tissue (CPFE), and no heartbeat (NHB). On the other hand, morphological anomalies of B-type did not occur at all in 0.4, 4.0, and 0.1 within 4 days, and the acute NOEC values of B-type were consistent with the chronic NOEC values at 32 days. This means that the concentration without any deformity in acute toxicity test during 4 days is consistent with the chronic NOEC value. That is, it is also a means to quickly calculate chronic NOEC using the acute NOEC value through the presence or absence of morphological abnormality in the Danio rerio embryo development stage of short term.

Effect of sublethal gradient concentrations of nickel on postlarvae of Penaeus monodon, Perna viridis and Terapon jarbua: Enzyme activities and histopathological changes

The present study evaluates the enzyme activities and histopathological changes in the post larvae (PL) of shrimp (Penaeus monodon), green mussel (Perna viridis) and fingerlings of crescent perch (Terapon jarbua) exposed to sublethal gradient concentrations of Nickel (Ni). The median lethal concentration (LC50) values were 2.49, 66.03 and 43.92 mg Ni L−1 derived for the PL of shrimp, green mussel and fish fingerlings respectively. No Observed Effect Concentration (NOEC), Lowest Observed Effect Concentration (LOEC) and chronic values of the PL of shrimp were 46.5, 73.0 and 58.3 μg Ni L−1 derived for the 21-d survival endpoint. The NOEC, LOEC and chronic values for the 30-d survival endpoint of the green mussels and fish fingerlings were 4.6, 6.32, 5.4 and 1.95, 2.6, 2.25 mg Ni L−1 respectively. The isoforms of esterase, superoxide dismutase and malate dehydrogenase activities in the whole body tissues of test organisms were studied by native polyacrylamide gel electrophoresis after exposure to Ni. Histological examination of compound eye sections of shrimp revealed deformation, compression, fusion and detachement in the corneal cells from the corneal facet of the ommatidia indicating cellular anomalies due to Ni toxicity. Gill sections of the green mussel witnessed reduced haemolymph in sinuses of gill filaments, degenerative changes in interfilamentous junction and necrosis of frontal ciliated epithelial cells with vacuoles after exposure to Ni. Nickel affects the vision of shrimp and fish fingerlings, gills and byssus of green mussels.

ACUTE TOXICITY OF CADMIUM (Cd) TO VELIGER LARVAE OF FLUTED GIANT CLAM (Tridacna squamosa LAMARCK, 1819)

Clams have a planktonic period which is sensitive to metal pollutants in the waters. The natural concentration of cadmium (Cd) is relatively low in marine waters but may increase with increasing anthropogenic activity on land that may be lethal to organisms, especially in the sensitive larval stages. The purpose of this study was to analyze the values of 24h-LC50, NOEC (No Observed Effect Concentration), LOEC (Lowest Observed Effect Concentration) and MATC (Maximum Acceptable Toxicant Concentration) along with the impact of acute Cd toxicity on mortality and morphological changes of Tridacna squamosa veliger. The toxicity test used was an acute toxicity test with a static method (4 replications). Acute toxicity tests were performed on veliger phase larvae with short-term exposure (24 hours) on various Cd concentrations ie., 0.1 mg/L, 1 mg/L, 2.5 mg/L, 5 mg/L and 10 mg/L . The 24h-LC50 value was calculated using the Trimmed Spearman-Karber application version 4.1, and the LOEC and NOEC values were analyzed using the Dunnet test. Results showed that the 24h-LC50 value of Cd applied to Tridacna squamosa veliger was 2.12 mg/L, whereas the NOEC, LOEC, and MATC values were 1 mg/L, 2.5 mg/L, 1.581 mg/L respectively. Mortalities were observed with increasing Cd concentrations. It was also shown a decreasing number of zooxanthellae, damaged in mantle tissue and shells, changes in shell color, released of mantle tissue from the shell with increasing Cd concentrations.

B-esterases and Behavioral Biomarkers in Tadpoles Exposed to Pesticide Pyrethroid-TRISADA®

The ecotoxic effects of pesticide used for mosquito’s control TRISADA® (TRI) [deltamethrin (D) 1%+tetramethrin (T) 0.33%, and piperonyl butoxide (PB) 0.29%] on amphibian larvae were investigated. In the laboratory, Rhinella arenarum tadpoles were exposed to nominal concentrations of 0.0000 (control; CO), 0.0003125% (C1); 0.000625% (C2); 0.00125% (C3); 0.0025% (C4); 0.005% (C5) (v/v) of formulated TRI. Median lethal concentration (LC50) (%) and 95% confidence limits (CL), the no-observedeffect concentration (NOEC), and the lowest-observedeffect concentration (LOEC) were quantified. The possible effects of TRI on B-esterases, evaluated through acetylcholinesterase (AChE) and carboxylesterase (CbE) activities, in addition to swimming performance (distance moved, mean speed, maximum speed, global activity, and resting time or immobility) were measured in tadpoles whose concentrations displayed survival rates higher than 50%. The 48 h LC50 of TRI was 0.00125% (v/v) [12.5 (D)+4.1 (T)+3.6 (PB); μg L-1] (CL: 0.000811- 0.001926%). The 48 h NOEC and LOEC values were 0.0003125% (v/v) [3.1 (D)+1 (T)+0.9 (PB); μg L-1] and 0.000625% (v/v) [6.2 (D) +2 (T) +1.8 (PB); μg L-1], respectively. At 48 h of exposure to upper sublethal TRI concentration assay (C3), AChE and CbE activities were significantly inhibited (68 and 84%, respectively) with respect to controls. Also, all the sublethal TRI concentrations caused significantly alterations of all swimming endpoints evaluated. The current study established that pesticide TRI is toxic to R. arenarum tadpoles and had detrimental effects on the B-sterases activities and swimming activity at TRI sublethal concentrations.

Comparative toxicity of chlorpyrifos: Sublethal effects on enzyme activities and histopathology of Mugil cephalus and Chanos chanos

Ecotoxicological data and potential impact of chlorpyrifos (CPF) in the region are scarce for prescribing safety limits. Therefore, toxicity and sublethal impact of CPF on fish fingerlings of Mugil cephalus (3.0 ± 1.2 cm) and Chanos chanos (3.0 ± 1.5 cm) were studied. Acute and chronic toxicity tests were conducted by continuous flow through method and derived 96 h median lethal concentration (LC50). Mean LC50 value of 1.13 μg/L for M. cephalus, and 3.20 μg/L for C. chanos were derived by Probit. Chronic toxicity tests were conducted for 30 days and determined no observed effect concentration values of 0.09 μg/L 0.17 μg/L and lowest observed effect concentration values of 0.16 μg/L 0.32 μg/L and chronic values of 0.13 μg/L 0.25 μg/L for M. cephalus and C. chanos respectively. Key biomarker enzyme activities viz., EST, SOD and MDH were studied at sublethal concentrations of CPF. Native gel electrophoresis revealed gradual decrease in isoforms of EST and SOD activities, whereas MDH activity increased in fingerlings. These responses indicate inhibition of cholinesterase, antioxidants and synthesis of ATPs in the cells due to CPF stress. Pathological lesions were evaluated in gill and eye tissues of fingerlings. Epithelial fusion and degenerative changes were prominent in primary lamellae. Hyperplasia, lifting epithelium, fusion of lamellae and necrosis were evidenced in the secondary lamellae. Cellular anomalies in the retina of the eye of C. chanos include vacuoles in nerve fiber layer, shrinkage of outer plexiform layer and detachment of pigment epithelium layer. These changes indicate physiological disturbance in the gill and eye.

Thiacloprid-induced toxicity influenced by nutrients: Evidence from in situ bioassays in experimental ditches.

Many studies show that neonicotinoid insecticides cause toxicity to aquatic invertebrates. Some studies report that insecticide toxicity may differ in combination with other agrochemicals under realistic field conditions. To explore such altered toxicity further, we aimed to determine the single and combined effects of environmentally relevant levels of the neonicotinoid thiacloprid and nutrients on different endpoints of 4 aquatic invertebrate species. Animals were exposed to these agrochemicals using a caged experiment within experimental ditches. We observed thiacloprid-induced toxicity for 2 crustaceans, Daphnia magna and Asellus aquaticus, and for 1 out of 2 tested insect species, Cloeon dipterum. We observed no toxic effects for Chironomus riparius at the time-weighted average test concentration of 0.51 μg thiacloprid/L. For D. magna, the observed toxicity, expressed as the lowest-observed-effect concentration (LOEC), on growth and reproduction was present at thiacloprid concentrations that were 2456-fold lower than laboratory-derived LOEC values. This shows that these species, when exposed under natural conditions, may exhibit neonicotinoid-induced toxic stress. Contrary to the low nutrient treatment, such toxicity was often not observed under nutrient-enriched conditions. This was likely attributable to the increased primary production that allowed for compensatory feeding. These findings warrant the inclusion of different feeding regimes in laboratory experiments to retrieve the best estimates of neonicotinoid-induced toxicity in the natural environment. Environ Toxicol Chem 2018;37:1907-1915. © 2018 SETAC.

Acute Toxicity of Colloidal Silicon Dioxide Nanoparticles on Amphibian Larvae: Emerging Environmental Concern

Fil: Lajmanovich, Rafael Carlos. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Effects of triphenyltin on reproduction in Japanese medaka (Oryzias latipes) across two generations

Triphenyltin (TPT) is an organotin compound used in marine anti-fouling coatings to prevent the attachment and growth of marine organisms, and it has negative effects on aquatic organisms. TPT is still detected at low concentrations, although its use has been prohibited at least in the European Community and is restricted in Japan as well. Studies using Japanese medaka (Oryzias latipes) indicate that TPT has the potential to inhibit reproduction. Although TPT is detected in many aquatic ecosystems, the multi-generational impact of TPT remains unknown. We investigated the two-generational effects of TPT on Japanese medaka and examined the relationships of several such effects between the F0 and F1 generations. Suppression of fecundity was observed in both generations, and fertility and growth were inhibited in the F1 generation. Moreover, delayed hatching and lower hatchability were observed in F1 embryos. Importantly, the value of the lowest observed effect concentration (LOEC) for these influences in F1 was lower than that in F0: that is, the LOEC values of fecundity and mortality were 3.2μg/L in the F0 generation and 1.0μg/L in the F1 generation. Fertility was not affected by TPT in F0, whereas it was significantly suppressed in the 1.0μg/L-exposure group of the F1 generation. Our results provide the first evidence of the effects of TPT on reproduction in a teleost fish across two generations, highlighting the concern that TPT could affect reproduction and mortality at decreasing concentrations in temporally overlapping generations.

Coupling biological assays with diffusive gradients in thin-films technique to study the biological responses of Eisenia fetida to cadmium in soil

This work sets out to investigate biological responses of Eisenia fetida to Cd, based on the bioavailable rather than total concentration of Cd, in soils. E. fetida was cultured for 14d in three selected Chinese soils amended with 0.1–40mgkg−1 Cd. Potentially bioavailable concentrations of Cd were measured in soil solution, in extractions using CaCl2 and HAc solutions, and using the technique of diffusive gradients in thin-films (DGT). Antioxidant system responses in E. fetida to Cd were measured as biological endpoints. Biological responses were more highly correlated with Cd concentrations evaluated using bioavailable methods than with total concentrations. Cd concentration measured using DGT and CaCl2 extraction provided the narrowest ranges of lowest observed effect concentration (LOEC) values based on biological responses, indicating the potential use of these measurements in management of soil quality and setting soil remediation standards. The LOEC values obtained from 15 field soils contaminated by Cd were similar to those from the three Cd-amended soils and suggested that DGT in particular can be a good tool to predict stress responses of E. fetida to Cd in soils. The study shows the potential of combining biological response and DGT measurements in risk assessment.

Effects of copper enrichment on survival, growth and photosynthetic pigment of seedlings and young plants of the eelgrass Zostera marina

ABSTRACTCopper (Cu2+) is an essential nutrient for plants but toxic at high concentrations. We subjected seedlings and young plants of eelgrass Zostera marina to different seawater Cu concentrations (3, 4, 5, 10, 30 and 50 µg l−1) for over 30 days under controlled laboratory conditions. Natural seawater without added Cu (3 µg l−1) was used as reference seawater. We measured plant response in terms of survivorship, morphology, growth, productivity and leaf pigment concentration. Survival analysis combined with morphological, dynamic and productive assessment suggested that the optimum seawater Cu concentration for the establishment of Z. marina seedlings and young plants is 4 μg l−1. The photosynthetic response of young plants to copper enrichment, including an increase in chlorophyll content under low Cu concentration treatment but significant decrease when treated with high concentrations of Cu, is similar to those reported for other seagrass species. NOEC (no observed effect concentration), LOEC (lowest observed effect concentration) and LC50 (lethal concentration that caused an increase in mortality to 50% of that of the control) values of seedlings were significantly lower than those of young plants, implying a reduced Cu tolerance to high concentrations (>10 μg l−1). This study provides data that could prove helpful in the development of successful eelgrass restoration and conservation.

Effect Factors for marine eutrophication in LCIA based on species sensitivity to hypoxia

Hypoxia is an important environmental stressor to marine species, especially in benthic coastal waters. Increasing anthropogenic emissions of nutrients and organic matter contribute to the depletion of dissolved oxygen (DO). Biotic sensitivity to low levels of DO is determined by the organisms’ ability to use DO as a respiratory gas, a process depending on oxygen partial pressure. A method is proposed to estimate an indicator of the intensity of the effects caused by hypoxia on exposed marine species. Sensitivity thresholds to hypoxia of an exposed ecological community, modelled as lowest-observed-effect-concentrations (LOEC), were compiled from literature for 91 benthic, demersal and benthopelagic species of fish, crustaceans, molluscs, echinoderms, annelids, and cnidarians, and converted to temperature-specific benthic (100m depth) LOEC values. Species distribution and LOEC values were combined using a species sensitivity distribution (SSD) methodology to estimate the DO concentration at which the potentially affected fraction (PAF) of the community's species having their LOEC exceeded is 50% (HC50LOEC). For the purpose of effect modelling in Life Cycle Impact Assessment (LCIA), Effect Factors (EF [(PAF)m3kgO2−1]) were derived for five climate zones (CZ) to represent the change in effect due to a variation of the stressor intensity, or EF=ΔPAF/ΔDO=0.5/HC50LOEC. Results range from 218 (PAF)m3kgO2−1 (polar CZ) to 306 (PAF)m3kgO2−1 (tropical CZ). Variation between CZs was modest so a site-generic global EF of 264 (PAF)m3kgO2−1 was also estimated and may be used to represent the average impact on a global ecological community of marine species exposed to hypoxia. The EF indicator is not significantly affected by the major sources of uncertainty in the underlying data suggesting valid applicability in characterisation modelling of marine eutrophication in LCIA.

Determination of lethal concentrations of indoxacarb in fingerling Cyprinus carpio at two temperatures

Acute (24-96 hrs) toxicity of indoxacarb, a new insecticide generation, was determined in Cyprinus carpio under the semi-static condition. Fish (~5 g) were exposed to increasing concentrations of indoxacarb over 24-96 hrs at 17oC, and over 24 hrs at 22oC, and mortality was recorded every 24 hrs. Indoxacarb-LC 50 values at 17oC were found to be 37.55, 20.92, 18.77 and 16.85 ppm after 24, 48, 72 and 96 hrs, respectively. LC 50 after 24 hrs at 22oC was 21.55 ppm, which was significantly lower than that obtained at 17oC. The lowest observed effect concentration (LOEC) values at 17oC were 14 ppm for 24, 48, 72 hrs, and 11 ppm for 96 hrs. No observed effect concentration (NOEC) values at 17oC were 11 ppm for 24, 48, 72 hrs, and 8 ppm for 96 hrs. NOEC and LOEC values after 24 hrs at 22oC were 8 and 11 ppm, respectively. The results indicated that indoxacarb is classified as harmful substance in common carp and, the higher temperature, the more toxicity of indoxacarb.