Feeding patterns of Lampanyctus pusillus (Pisces: Myctophidae) throughout its ontogenetic development

The trophic ecology of the lanternfish Lampanyctus pusillus was investigated using individuals captured off the Balearic Islands (39°N, 2°E) (western Mediterranean) in December 2009. Based on gut content analyses, the trophic niche breadth, diet composition and selectivity were determined for the entire life cycle of L. pusillus. The larval stages fed actively near the surface during the day, with a feeding incidence (FI) of approximately 71 %. In contrast, the adults fed at night, both in near-surface depths and in the 400 m deep scattering layer, with a higher FI (83 %). Diet analysis revealed a shift in the prey choice throughout ontogenetic development, from preflexion individuals, which selected nauplii and small oncaeids, to postflexion larvae, which consumed a variety of calanoids, mainly Clausocalanus spp., to the adults, which preyed on large organisms, exhibiting positive selectivity for Pleuromamma spp. and euphausiids. These results show that the vertical distribution of larvae and adults is partly conditioned by their respective feeding habits, with larvae feeding on small zooplankton in the upper layer and adults preferring to consume larger taxa that perform nycthemeral migrations.     

Phytoremediation of potentially toxic elements using constructed wetlands in coastal areas with a mining influence

Environmental Geochemistry and Health - This paper proposes the use of wetlands as a phytoremediation strategy for areas of mining and maritime influence in the southeast of Spain. Potentially...     

Acute toxicity of arsenic to Aliivibrio fischeri (Microtox® bioassay) as influenced by potential competitive–protective agents

In this study, we investigated the effect of some potential alleviative compounds against the acute toxicity of arsenic (As^V, As^III and DMA^V) on Aliivibrio fischeri (formerly Vibrio fischeri), a bioluminescent model bacterium, through the Microtox® bioassay. The compounds studied differed in their mechanism of action, and they included the following: phosphate and glycerol, as chemical analogues (and potential competitors) of As^V or As^III, respectively; citrate, a weak natural organic ligand; and the antioxidant ascorbic acid. Special attention was paid to phosphate effects, a widespread pollutant in natural environments. As^V was found to be more acutely toxic than As^III to A. fischeri, in accordance with its higher interaction with the bacteria. Both As^V and As^III were found to be much more acutely toxic than DMA^V, which was essentially non-acutely toxic even at very high concentrations. Phosphate presence (at equimolar P/As ratios or higher) resulted in the almost total suppression of bioluminescence inhibition, suggesting it exerts an alleviative effect against As^V acute toxicity on A. fischeri. Interestingly, the uptake and the percentage of extracellular As^V were not affected by the addition of phosphate, suggesting that such protective effect does not result from the competition for their common transporters. In contrast, the acute toxicity of As^III was essentially unaffected by phosphate. Glycerol did not decrease the acute toxicity or the uptake of As^III by A. fischeri, denoting the likely occurrence of an additional mechanism for As^III uptake in such bacteria. Similarly, citrate and ascorbic acid essentially did not caused alleviation of As^V or As^III acute toxicity. As for environmental and operational implications, P could beneficially protect aquatic microorganisms against acute detrimental effects of As^V, whilst its presence could mask the toxicity due to As^V when assessed using the Microtox® bioassay, thus leading to seriously underestimate the actual ecological and health risks.     

Sea-urchin (Paracentrotus lividus) glutathione S-transferases and cholinesterase activities as biomarkers of environmental contamination

Activities of glutathione S-transferases (GST) and cholinesterase (ChE) from Paracentrotus lividus were investigated as possible biomarkers of environmental contamination in the coastal zone. In the first phase of the study, the activity of both enzymes was determined in various tissues in order to select the most appropriate ones to be used in the following assays. In the second phase, the ChEs present in ambulacra were characterized using different substrates and selective inhibitors. In the next phase, laboratory bioassays were performed with dilutions of water-accommodated fraction of #4 fuel-oil (WAF) and benzo[a]pyrene (BaP) to determine the response of those enzymes to these pollutants and, finally, the activity of both enzymes was determined during a year in indigenous specimens from six sites on the Northwest coast of Portugal, with different pollution levels, to determine basal values and seasonal variations of ChE and GST activities. Among the several tissues tested, ambulacra and the anterior portion of the intestine were selected for ChE and GST assays, respectively. The determination of ChE in ambulacra tissue may be performed in a non-destructive way. Ambulacra ChE hydrolysed acetylthiocholine preferentially to propionylthiocholine and butyrylthiocholine and, inhibition by excess of substrate was observed. Enzymatic activity was almost fully inhibited by eserine sulfate (>98%) at concentrations equal or higher than 6.25 microM. Sensitivity to both BW284C51 (reaching 98% at 200 microM) and iso-OMPA (73% at 8 mM) was found. In laboratory bioassays, GSTs activity was inhibited by WAF and induced by BaP, whereas ChE activity was not affected by any of these environmental contaminants. Seasonal variations in enzymatic activities were found. For example, in a reference site, ChE values changed from 52.2 +/- 9.3 U mg(-1) protein in autumn to 71.8 +/- 13.3 U mg(-1) protein in spring, while GST activity changed from 129.9 +/- 29.8 U mg(-1) protein in winter to 279.0 +/- 48.0 U mg(-1) protein in autumn. Sea-urchins from reference sites presented significantly higher values of both ChE and GST than animals from contaminated sites in all seasons. In conclusion, the results of this study indicate that (i) ambulacra and the anterior portion of intestine are the most suitable tissues to measure ChE and GST activities, respectively; (ii) only one form of ChE seems to be present in ambulacra, showing properties of both typical acetylcholinesterase (AChE) and pseudocholinesterase (PChE); (iii)P. lividus GST is sensitive to both WAF and BaP even after acute exposures while ChE is not, and (iv) in spite of the significant seasonal variations observed in both enzymes in the field, P. lividus ChE and GST were capable of discriminate sites with different contamination levels and, thus, they are suitable for use as biomarkers in biomonitoring studies in the coastal zone.     

Urinary arsenic levels influenced by abandoned mine tailings in the Southernmost Baja California Peninsula,Mexico

Gold has been mined at San Antonio-El Triunfo, (Baja California Sur, Mexico) since the 18th century. This area has approximately 5,700 inhabitants living in the San Juan de Los Planes and El Carrizal hydrographic basins, close to more than 100 abandoned mining sites containing tailings contaminated with potentially toxic elements such as arsenic. To evaluate the arsenic exposure of humans living in the surrounding areas, urinary arsenic species, such as inorganic arsenic (iAs) and the metabolites mono-methylated (MMA) and di-methylated arsenic acids (DMA), were evaluated in 275 residents (18–84 years of age). Arsenic species in urine were analyzed by hydride generation-cryotrapping-atomic absorption spectrometry, which excludes the non-toxic forms of arsenic such as those found in seafood. Urinary samples contained a total arsenic concentration (sum of arsenical species) which ranged from 1.3 to 398.7 ng mL^?1, indicating 33 % of the inhabitants exceeded the biological exposition index (BEI = 35 ng mL^?1), the permissible limit for occupational exposure. The mean relative urinary arsenic species were 9, 11 and 80 % for iAs, MMA and DMA, respectively, in the Los Planes basin, and 17, 10 and 73 %, respectively, in the El Carrizal basin. These data indicated that environmental intervention is required to address potential health issues in this area.     

Removal of metal ions from aqueous solution by chelating polymeric hydrogel

Polysaccharide natural seed coat from the tree Magonia pubescens, in the form of hydrogel was used to remove metals in aqueous solution. Swelling tests indicate that seed coat presents hydrogel behavior, with maximum water absorption of 292 g water/g. Adsorption experiments performed using Na⁺, Mg²⁺, K⁺, Ca²⁺, Cr³⁺, Fe³⁺ and Zn²⁺ demonstrated that the polysaccharide structure has a high capacity to extract these ions from the aqueous solution. Scanning electron microscopy revealed significant morphological changes of the material before and after water contact. Differential scanning calorimetry measurements indicate a signal shift of the water evaporation temperature in the material with adsorbed zinc. X-ray photoelectron spectroscopy analysis combined with theoretical studies by the density functional theory and on Hartree–Fock (HF) level evidence that the metallic ions were adsorbed through coordination with hydroxyl groups of polysaccharide. In the case of Zn²⁺ the lowest HF energy was observed for the tetracoordination mode, where Zn²⁺ is coordinated by two hydroxyl groups and two water molecules.     

Perceived safety climate, job demands, and coworker support among union and nonunion injured construction workers

PROBLEM: This study evaluated injured construction workers' perceptions of workplace safety climate, psychological job demands, decision latitude, and coworker support, and the relationship of these variables to the injury severity sustained by the workers. METHODS: Injury severity was assessed using the Health Assessment Questionnaire (HAQ), which evaluates functional limitations. Worker perceptions of workplace variables were determined by two instruments: (a) the Safety Climate Measure for Construction Sites and (b) the Job Content Questionnaire (JCQ). RESULTS: The overall model explained 23% of the variance in injury severity, with unique contributions provided by union status, the Safety Climate Score, and Psychological Job Demands. A positive significant correlation was found between injury severity and the Safety Climate Scores (r = .183, P = .003), and between the Safety Climate Scores and union status (r = .225, P < .001). DISCUSSION: There were statistically significant differences between union and nonunion workers' responses regarding perceived safety climate on 5 of the 10 safety climate items. Union workers were more likely than nonunion workers to: (a) perceive their supervisors as caring about their safety; (b) be made aware of dangerous work practices; (c) have received safety instructions when hired; (d) have regular job safety meetings; and (e) perceive that taking risks was not a part of their job. However, with regard to the 49-item JCQ, which includes Coworker Support, the responses between union and nonunion workers were very similar, indicating an overall high degree of job satisfaction. However, workers who experienced their workplace as more safe also perceived the level of management (r = -.55, P < .001) and coworker (r = -.31, P < .001) support as being higher. IMPACT ON INDUSTRY: The findings of this study underscore the critical need for construction managers to alert workers to dangerous work practices and conditions more frequently, and express concern and praise workers for safe work in a manner that is culturally acceptable in this industry. Workplace interventions that decrease the incidence and severity of injuries, but that are flexible enough to meet a variety of potentially competing imperatives, such as production deadlines and client demands, need to be identified.     

Monitoring SARS-CoV-2 in the Wastewater and Rivers of Tapachula,a Migratory Hub in Southern Mexico

Food and Environmental Virology - The COVID-19 pandemic has been monitored by applying different strategies, including SARS-CoV-2 detection with clinical testing or through wastewater-based...     

The role of leaf litter as a protective barrier for copper-containing pesticides in orchard soils

Environmental Science and Pollution Research - This study assessed the capacity of leaf litters to adsorb copper ions applied as a copper-based pesticide. Leaf litters of two fruit tree species...