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The aim of the present study was to determine the influence of salinity and organism age on the chronic toxicity of waterborne lead (Pb) to Atherinops affinis and to compare the relative Pb sensitivity of A. affinis with other marine species. Chronic Pb exposure experiments were conducted in a water flow-through testing system. Survival, standard length, dry weight, and tissue Pb concentration were measured and lethal concentrations (LCs), effect concentrations (ECs), and bioconcentration factors (BCFs) were calculated. In general, increasing salinity and organism age decreased Pb toxicity. The LC50s for larval fish at 14 and 28 ppt salinity were 15.1 and 79.8 μg/L dissolved Pb, respectively; whereas, the LC50 for juvenile fish was 167.6 μg/L dissolved Pb at 28 ppt salinity. Using standard length data, the EC10 values for larval fish were 16.4 and 82.4 μg/L dissolved Pb at 14 and 28 ppt salinity, respectively. The dry weight EC25s for low and high salinity were 15.6 and 61.84 μg/L dissolved Pb, respectively. The BCFs were higher with the lower salinity study (1703) in comparison to the higher salinity study (654). Results of Pb speciation calculation showed higher fraction of Pb 2+ in water with lower salinity, explaining the higher observed toxicity of Pb in lower salinity water than higher salinity water. Atherinops affinis is more sensitive to Pb than several other marine species. Evidence of abnormal swimming and skeletal deformities were observed in Pb exposure treatments. Results of the present study are useful for marine biotic ligand modeling and support ecological risk assessment and deriving Pb environmental quality criteria for marine environments. Environ Toxicol Chem 2018;37:2705-2713. © 2018 SETAC., (© 2018 SETAC.)

A comprehensive probabilistic terrestrial ecological risk assessment (ERA) was conducted to characterize the potential risk of mosquito control insecticide (i.e., naled, it's metabolite dichlorvos, and permethrin) usage to adult butterflies in south Florida by comparing the probability distributions of environmental exposure concentrations following actual mosquito control applications at labeled rates from ten field monitoring studies with the probability distributions of butterfly species response (effects) data from our laboratory acute toxicity studies. The overlap of these distributions was used as a measure of risk to butterflies. The long-term viability (survival) of adult butterflies, following topical (thorax/wings) exposures was the environmental value we wanted to protect. Laboratory acute toxicity studies (24-h LD50) included topical exposures (thorax and wings) to five adult butterfly species and preparation of species sensitivity distributions (SSDs). The ERA indicated that the assessment endpoint of protection, of at least 90% of the species, 90% of the time (or the 10th percentile from the acute SSDs) from acute naled and permethrin exposures, is most likely not occurring when considering topical exposures to adults. Although the surface areas for adulticide exposures are greater for the wings, exposures to the thorax provide the highest potential for risk (i.e., SSD 10th percentile is lowest) for adult butterflies. Dichlorvos appeared to present no risk. The results of this ERA can be applied to other areas of the world, where these insecticides are used and where butterflies may be exposed. Since there are other sources (e.g., agriculture) of pesticides in the environment, where butterfly exposures will occur, the ERA may under-estimate the potential risks under real-world conditions., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The uptake and effects (survival, weight) of copper (Cu) on Florida apple snails (Pomacea paludosa) via exposures to copper-enriched agricultural soil-water and water-only treatments were investigated. Soils were collected from citrus sites in south Florida and flooded with laboratory freshwater for 14d. Neonate apple snails (96-h-old) were then exposed to either Cu from a soil-overlying water (i.e., flooded agricultural soils) treatment or overlying water-only (i.e., equilibrated overlying water produced from 14d flooding of agriculture soils) treatment for 14d under standard laboratory conditions. Survival, weight (dry, wet), and whole body Cu uptake were measured. Copper exposure via soil-water exposures resulted in higher mortality and whole body Cu uptake than water-only exposures, indicating Cu uptake from soils. However, snail wet and dry weights were higher in soil-water treatments than in water-only treatments. Micronutrients from soils may be consumed by snails increasing weights. Survival, apple snail dry weight, and whole body Cu concentrations were significantly correlated with soil and water Cu concentrations in soil-water treatments. Survival was significantly correlated with the concentration of Cu(CO3)2(2-) in water-only treatments. This suggests that Cu(CO3)2(2-) is toxic to apple snails. Whole body Cu concentrations were higher in surviving snails than dead snails, suggesting that apple snails have the ability to detoxify accumulated Cu (e.g., through metallothionein induction, granules).

Research on the toxicity of arsenic has focused on sublethal effects that do not provide sufficient information for risk estimation. While most studies have focused on organism response to constant arsenic exposures, organisms in nature are exposed to fluctuating As concentrations. Consequently, results obtained from standardized bioassays with constant exposures may not adequately characterize risk to indigenous biota. This research was designed to characterize the response of Daphnia magna to fluctuating arsenic exposures during 21-day experiments. At concentrations > or =3000 microg/L As, 21-day pulsed exposure mortality increased as a function of exposure concentration and duration. In addition, 21-day pulsed exposure mortality increased with increasing recovery time. Pulsed As exposure did not affect the growth of D. magna over 21 days. Twenty-one day accumulative reproduction of D. magna was only affected by pulsed exposures of high As concentration and long durations.