Some anthropogenic noise is now considered pollution, with evidence building that noise from human activities such as transportation, construction and exploration can impact behaviour and physiology in a broad range of taxa. However, relatively little research has considered the effects of repeated or chronic noise; extended exposures may result in habituation or sensitisation, and thus changes in response. We conducted a field-based experiment at Moorea Island to investigate how repeated exposure to playback of motorboat noise affected a coral reef fish (Dascyllus trimaculatus). We found that juvenile D. trimaculatus increased hiding behaviour during motorboat noise after two days of repeated exposure, but no longer did so after one and two weeks of exposure. We also found that naïve individuals responded to playback of motorboat noise with elevated ventilation rates, but that this response was diminished after one and two weeks of repeated exposure. We found no strong evidence that baseline blood cortisol levels, growth or body condition were affected by three weeks of repeated motorboat-noise playback. Our study reveals the importance of considering how tolerance levels may change over time, rather than simply extrapolating from results of short-term studies, if we are to make decisions about regulation and mitigation.

Little is known about the propensity of crocodilians to bioaccumulate trace elements as a result of chronic dietary exposure. We exposed 36 juvenile alligators (Alligator mississippiensis) to one of four dietary treatments that varied in the relative frequency of meals containing prey from coal combustion waste (CCW)-contaminated habitats vs. prey from uncontaminated sites, and evaluated tissue residues and growth rates after 12 mo and 25 mo of exposure. Hepatic and renal concentrations of arsenic (As), cadmium (Cd) and selenium (Se) varied significantly among dietary treatment groups in a dose-dependent manner and were higher in kidneys than in livers. Exposure period did not affect Se or As levels but Cd levels were significantly higher after 25 mo than 12 mo of exposure. Kidney As and Se levels were negatively correlated with body size but neither growth rates nor body condition varied significantly among dietary treatment groups. Our study is among the first to experimentally examine bioaccumulation of trace element contaminants in crocodilians as a result of chronic dietary exposure. A combination of field surveys and laboratory experiments will be required to understand the effects of different exposure scenarios on tissue residues, and ultimately link these concentrations with effects on individual health.

The role of hydrogen sulfide (H₂S) is well known in the regulation of abiotic stress such as toxic heavy metal. However, mechanism(s) lying behind this amelioration are still poorly known. Consequently, the present study was focused on the regulation/mitigation of hexavalent chromium (Cr(VI) toxicity by the application of H₂S in wheat and rice seedlings. Cr(VI) induced accumulation of reactive oxygen species and caused protein oxidation which negatively affect the plant growth in both the cereal crops. We noticed that Cr(VI) toxicity reduced length of wheat and rice seedlings by 21% and 19%, respectively. These reductions in length of both the cereal crops were positively related with the down-regulation in the ascorbate-glutathione cycle, and were recovered by the application NaHS (a donor of H₂S). Though exposure of Cr(VI) slightly stimulated sulfur assimilation but addition of H₂S further caused enhancement in sulfur assimilation, suggesting its role in the H₂S-mediated Cr(VI) stress tolerance in studied cereal crops. Overall, the results revealed that H₂S renders Cr(VI) stress tolerance in wheat and rice seedlings by stimulating sulfur assimilation and ascorbate-glutathione which collectively reduce protein oxidation and thus, improved growth was observed.

The decreasing ocean pH seems to adversely affect marine organisms, including crustaceans, which leads to potential threats to seafood safety. The present investigation evaluated the effect of seawater acidification on the edible marine mud crab Scylla serrata instars. The experimental setup was designed using a multi-cell cage based system assembled with 20 pre holed PVC pipes containing 20 individual crabs to avoid cannibalism. The crab instars were exposed to CO₂ driven acidified seawater at pH 7.8 (IPCC forecast pH at the end of the 21ˢᵗ century), 7.6, 7.4, 7.2, and 7.0 for 60 days. The crabs reared in seawater without acidification at pH 8.2 served as control. The present study revealed a notable decrease in survival, feed intake, growth, molting, tissue biochemical constituents, minerals, chitin, and alkaline phosphatase in S. serrata instar reared in acidified seawater, denotes the adverse effect of seawater acidification on crabs. The significant elevations in antioxidants, lipid peroxidation, and metabolic enzymes in all acidified seawater compared to ambient pH indicates the physiological stress of the crabs' instars. The changes in the metabolic enzymes reveal the metabolism of protein and glucose for additional energy required by the crabs to tolerate the acidic stress. Hence, the present study provides insight into the seawater acidification can adversely affect the crab S. serrata.

Urban environments are characterized by multiple exposures that may influence body mass index (BMI) growth in early life. Previous studies are few, with inconsistent results and no evaluation of simultaneous exposures. Thus, this study aimed to assess the associations between exposure to air pollution, green spaces and built environment characteristics, and BMI growth trajectories from 0 to 5 years. This longitudinal study used data from an electronic primary care health record database in Catalonia (Spain), including 79,992 children born between January 01, 2011 and December 31, 2012 in urban areas and followed until 5 years of age. Height and weight were measured frequently during childhood and BMI (kg/m²) was calculated. Urban exposures were estimated at census tract level and included: air pollution (nitrogen dioxide (NO₂), particulate matter <10 μm (PM₁₀) and <2.5 μm (PM₂.₅₎), green spaces (Normalized Difference Vegetation Index (NDVI) and % green space) and built environment (population density, street connectivity, land use mix, walkability index). Individual BMI trajectories were estimated using linear spline multilevel models with several knot points. In single exposure models, NO₂, PM₁₀, PM₂.₅, and population density were associated with small increases in BMI growth (e.g. β per IQR PM₁₀ increase = 0.023 kg/m², 95%CI: 0.013, 0.033), and NDVI, % of green spaces and land use mix with small reductions in BMI growth (e.g. β per IQR % green spaces increase = −0.015 kg/m², 95%CI: −0.026, −0.005). These associations were strongest during the first two months of life. In multiple exposure models, most associations were attenuated, with only those for PM₁₀ and land use mix remaining statistically significant. This large longitudinal study suggests that early life exposure to air pollution, green space and built environment characteristics may be associated with small changes in BMI growth trajectories during the first years of life, and that it is important to account for multiple exposures in urban settings.

To assess the effects of elevated concentrations of carbon dioxide (CO2) and ozone (O3) on the growth of two mid-successional oak species native to East Asia, Quercus mongolica var. crispula and Quercus serrata, we measured gas exchange and biomass allocation in seedlings (initially 1-year-old) grown under combinations of elevated CO2 (550 μmol mol−1) and O3 (twice-ambient) for two growing seasons in an open-field experiment in which root growth was not limited. Both the oak species showed a significant growth enhancement under the combination of elevated CO2 and O3 (indicated by total dry mass; over twice of ambient-grown plants, p < .05), which probably resulted from a preferable biomass partitioning into leaves induced by O3 and a predominant enhancement of photosynthesis under elevated CO2. Such an over-compensative response in the two Japanese oak species resulted in greater plant growth under the combination of elevated CO2 and O3 than elevated CO2 alone.

The present study was conducted to assess morphological, biochemical and yield responses of palak (Beta vulgaris L. cv Allgreen) to ambient and elevated levels of CO2 and O3, alone and in combination. As compared to the plants grown in charcoal filtered air (ACO2), growth and yield of the plants increased under elevated CO2 (ECO2) and decreased under combination of ECO2 with elevated O3 (ECO2 + EO3), ambient O3 (ACO2 + AO3) and elevated O3 (EO3). Lipid peroxidation, ascorbic acid, catalase and glutathione reductase activities enhanced under all treatments and were highest in EO3. Foliar starch and organic carbon contents increased under ECO2 and ECO2 + EO3 and reduced under EO3 and ACO2 + AO3. Foliar N content declined in all treatments compared to ACO2 resulting in alteration of C/N ratio. This study concludes that ambient level of CO2 is not enough to counteract O3 impact, but elevated CO2 has potential to counteract the negative effects of future O3 level.

Guidelines provided by OECD and EPPO allow the use of data obtained in greenhouse experiments in the risk assessment for pesticides to non-target terrestrial plants in the field. The present study was undertaken to investigate the predictability of effects on field-grown plants using greenhouse data. In addition, the influence of plant development stage on plant sensitivity and herbicide efficacy, the influence of the surrounding vegetation on individual plant sensitivity and of sublethal herbicide doses on the biomass, recovery and reproduction of non-crop plants was studied. Results show that in the future, it might well be possible to translate results from greenhouse experiments to field situations, given sufficient experimental data. The results also suggest consequences at the population level. Even when only marginal effects on the biomass of non-target plants are expected, their seed production and thereby survival at the population level may be negatively affected. The response of greenhouse-grown wild plant species to herbicide exposure could be related to the response of the same species when grown in the field.

Growth is an important toxicity end-point in ecotoxicology but is rarely used in soil ecotoxicological studies. Here, we assessed the growth change of Oppia nitens when exposed to reference and heavy metal toxicants. To assess mite growth, we developed an image analysis methodology to measure colour spectrum changes of the mite integument at the final developmental stage, as a proxy for growth change. We linked the values of red, green, blue, key-black, and light colour of mites to different growth stages. Based on this concept, we assessed the growth change of mites exposed to cadmium, copper, zinc, lead, boric acid, or phenanthrene at sublethal concentrations in LUFA 2.2 soil for 14 days. Sublethal effects were detected after 7 days of exposure. The growth of O. nitens was more sensitive than survival and reproduction when exposed to copper (EC50growth = 1360 mg/kg compared to EC50reproduction = 2896 mg/kg). Mite growth sensitivity was within the same order of magnitude to mite reproduction when exposed to zinc (EC50growth = 1785; EC50reproduction = 1562 mg/kg). At least 25% of sublethal effects of boric acid and phenanthrene were detected in the mites but growth was not impacted when O. nitens were exposed to lead. Consistent with previous studies, cadmium was the most toxic metal to O. nitens. The mite growth pattern was comparable to mite survival and reproduction from previous studies. Mite growth is a sensitive toxicity endpoint, ecologically relevant, fast, easy to detect, and can be assessed in a non-invasive fashion, thereby complimenting existing O. nitens testing protocols.

The number of published studies evaluating the effects of microplastics (MPs) in fish has increased in the last decade. However, of the available studies, few have explored the long-term effects of MPs on fish growth and reproduction and have resorted to MPs in the form of μm-sized beads/microspheres. In this study, 6-10 day-old post-hatch medaka (Oryzias latipes) fish were exposed to 50 (i.e. 1X) and 500 (i.e. 10X) μg of heterogeneously sized and irregularly shaped virgin polystyrene (PS) MP particles (200-μm range)/L for 150 days. These concentrations corresponded to respective daily mean values of 247 and 3087 particles/L administered through the diet. The PS MPs dietary exposure resulted in body burdens of 114 and 440 particles/g fish on day 50, and of 78 and 173 particles/g fish on day 100 since the respective exposures to the 1X and the 10X treatments started. The biometric analyses found no incidence of PS MPs ingestion on overall fish growth and development. The histological survey in the 10X group did not reveal alterations in gills or in the digestive tract. Mild alterations in other organs were seen and included increased fluid material in the peritoneal cavity, glomerular and tubular alterations in kidneys, and differences in the diameter of the thyroid follicles and thickness of the follicular epithelial cells. The initial days of the reproductive phase revealed MP-related differences in the number of gravid females, fecundity, and fertilization rates. Overall, these values reverted to normal rates throughout the succeeding days. No significant effects of PS MPs exposure were evidenced on offspring success. The 150-day PS MPs dietary exposure used in this study provided clues of histological effects and a reproduction delay. However, it did not seem to compromise overall growth/thriving and the ongoing reproduction.