Laboratory Exposure Research Articles

Effects of early clinical and basic laboratory exposure program on premedical students: a questionnaire survey.

BackgroundBecause premed students do not take courses related to medicine during their first 2 years, they cannot establish their identity as students at medical schools, making it difficult for them to set goals as future doctors. We conducted an early clinical and basic laboratory exposure program for premed students and studied the effects of the program and student satisfaction levels. MethodsWe performed an early clinical and basic laboratory exposure program for premed students for 2 days and evaluated the effects of the program and student satisfaction with it. The program consisted of two types: type 1, where two to four students formed a group, which was assigned to a particular department to participate and make observations during ward rounds, outpatient clinics, examinations, procedures, and surgeries (in the case of basic laboratory work, the students partook in experimental observations); and type 2, where one student followed a medical school professor to observe the professor’s day. After the program ended, an online survey was conducted to investigate the effects on students, their thoughts, and satisfaction levels.ResultsIn total, 114 students (91.2%) responded to the survey. Approximately 94% of them were satisfied with the program. They found that the program would be useful for deciding on future career paths, gaining knowledge about a department of interest, studying for a medical program after premedical studies, and befriending residents and professors in certain departments. ConclusionEarly clinical and basic laboratory exposure programs are recommended for premedical students.

Wi-Fi technology and human health impact: a brief review of current knowledge.

An enormous increase in the application of wireless communication in recent decades has intensified research into consequent increase in human exposure to electromagnetic (EM) radiofrequency (RF) radiation fields and potential health effects, especially in school children and teenagers, and this paper gives a snap overview of current findings and recommendations of international expert bodies, with the emphasis on exposure from Wi-Fi technology indoor devices. Our analysis includes over 100 in vitro, animal, epidemiological, and exposure assessment studies (of which 37 in vivo and 30 covering Wi-Fi technologies). Only a small portion of published research papers refers to the “real” health impact of Wi-Fi technologies on children, because they are simply not available. Results from animal studies are rarely fully transferable to humans. As highly controlled laboratory exposure experiments do not reflect real physical interaction between RF radiation fields with biological tissue, dosimetry methods, protocols, and instrumentation need constant improvement. Several studies repeatedly confirmed thermal effect of RF field interaction with human tissue, but non-thermal effects remain dubious and unconfirmed.

Combined impact of UV radiation and nitric acid on high‐density polyethylene containers as a laboratory test

AbstractIn a laboratory test, transparent high‐density polyethylene (HDPE) jerrycans have been exposed to both UV radiation and 55 wt‐% nitric acid solution at (41 ± 2)°C, for up to 20 days. For comparison, UV radiant exposure (21 days) and nitric acid exposure (up to 6 weeks) were performed separately, at nearly equal temperatures. The damages are compared with FTIR spectroscopy in ATR and HT‐gel permeation chromatography(GPC) on a molecular level and with hydraulic internal pressure testing as a component test. For the used jerrycans, relevant oxidation can only be found after the combined exposure. This is caused by the decomposition of nitric acid into nitrous gases by UV radiation, which is also observed at lower concentrations (28 wt‐%). After 6 days of laboratory exposure, this is rated as critical, which corresponds to about 1/10 year in Central Europe, according to the UV radiant exposure. The gradual increase in oxidative damage shows the reproducibility of the test.

Invertebrate metal accumulation and toxicity from sediments affected by the Mount Polley mine disaster.

On August 4, 2014, a tailings dam failed at the Mount Polley copper and gold mine near Likely, British Columbia, Canada, releasing approximately 25 M m[Formula: see text] of contaminated water and solid tailings material into Polley and Quesnel lakes. Water, sediment, freshwater scuds (Hyalella azteca), and mayfly larvae (Ephemeroptera) were collected during the summer of 2018 from Polley Lake, affected and unaffected sites in Quesnel Lake, and both mine-contaminated and clean far-field sites as references. Analytical results indicated that invertebrates from sites affected by the tailings breach had elevated metal concentrations relative to those from non-affected or reference sites. We conducted a controlled laboratory exposure to determine if laboratory-reared Hyalella azteca metal concentrations were related to field-collected water or sediments from the same sites as the field study. Half of the replicates prevented amphipods from directly contacting sediments (water-only exposure), while the other half allowed them direct access (sediment and water exposure). Whole-body Cu concentration was highest in Hyalella exposed to substrate from the most contaminated sites as well as in treatments where they were allowed direct access to sediments. Hyalella having direct access to metal-contaminated sediments showed reduced survival and growth relative to those in reference or control treatments. These results suggest that metals from the fine sediments associated with the Mount Polley mine disaster are bioavailable and potentially toxic to epibenthic invertebrates, even several years after the initial breach.

Effects of Two Toxin-Producing Harmful Algae, Alexandrium catenella and Dinophysis acuminata (Dinophyceae), on Activity and Mortality of Larval Shellfish.

Harmful algal bloom (HAB) species Alexandrium catenella and Dinophysis acuminata are associated with paralytic shellfish poisoning (PSP) and diarrhetic shellfish poisoning (DSP) in humans, respectively. While PSP and DSP have been studied extensively, less is known about the effects of these HAB species or their associated toxins on shellfish. This study investigated A. catenella and D. acuminata toxicity in a larval oyster (Crassostrea virginica) bioassay. Larval activity and mortality were examined through 96-h laboratory exposures to live HAB cells (10–1000 cells/mL), cell lysates (1000 cells/mL equivalents), and purified toxins (10,000 cells/mL equivalents). Exposure to 1000 cells/mL live or lysed D. acuminata caused larval mortality (21.9 ± 7.0%, 10.2 ± 4.0%, respectively) while exposure to any tested cell concentration of live A. catenella, but not lysate, caused swimming arrest and/or mortality in >50% of larvae. Exposure to high concentrations of saxitoxin (STX) or okadaic acid (OA), toxins traditionally associated with PSP and DSP, respectively, had no effect on larval activity or mortality. In contrast, pectenotoxin-2 (PTX2) caused rapid larval mortality (49.6 ± 5.8% by 48 h) and completely immobilized larval oysters. The results indicate that the toxic effects of A. catenella and D. acuminata on shellfish are not linked to the primary toxins associated with PSP and DSP in humans, and that PTX2 is acutely toxic to larval oysters.

Examining the Impact of Cadaver‐Based Anatomy Laboratory Experiences on Medical Students Through a Thematic Analysis of their Written Reflections

Cadaver dissection has long been considered the gold standard pedagogical approach in anatomical education for its ability to teach students not only anatomy knowledge, but also non‐traditional discipline‐independent skills that are pertinent to professional training programs in healthcare. With the onset of the COVID‐19 pandemic in 2020, many medical schools were forced to adopt remote or blended teaching formats, reducing students’ dissection time in the anatomy laboratory. Some have raised concerns about how having limited interaction with body donors in anatomical education may dehumanize medical students’ learning experiences and alter their learning outcomes, but there is a paucity of research in this area. To examine how reduced exposure to cadavers during the COVID‐19 pandemic may impact the student experience, a pre‐pandemic assessment must first be made. Halfway through the first year of medical school, McGill University medical students consider the meaning of their anatomy laboratory experience and how it has contributed to their future career through a written reflective assignment. The present study aimed to describe how students reflected on their laboratory experience and its importance in their training as both individuals and future healthcare professionals, prior to the onset of COVID‐19. Reflections written by the McGill University medical class of 2023, whose time in the anatomy laboratory was not limited by the pandemic, were analyzed through the six‐step framework to thematic analysis by Braun and Clarke (2006). Three undergraduate research students (BB, MR, IG) inductively coded students’ reflections (n = 134) using NVivo software to identify preliminary themes. Themes were reviewed, defined, and named through discussion with the entire research team (all listed authors). Three central themes were identified: (1) philosophical reflections, (2) perceived outcomes of the anatomy laboratory and (3) reflections on the body donor or body donation. Notable sub‐themes included: (1.1) reflections on the body and soul, (2.1) reflections on the current medical curriculum and (3.1) the dichotomy of objectification and personification during student‐donor interaction. The presence of these themes and example quotes drawn from the reflections confirm that donor‐dissection not only teaches students anatomical knowledge but enables them to realize the importance of dissection to the medical curriculum, consider the gift that is body donation, and explore philosophical ideas of life and death. A thematic analysis of the reflections written by McGill University’s 2024 medical class, who were subject to a blended learning format during the COVID‐19 pandemic, is currently underway to determine the degree to which decreased laboratory exposure influenced the students’ reflections on their laboratory experience.

Toxic exposure in a clinical pathology laboratory as a potential occupational hazard causing small fibre neuropathy

Introduction. Small fibre neuropathy (SFN) is a heterogeneous condition involving the thinly-myelinated Aδ and unmyelinated C-fibres, characterised by pain and altered temperature sensation and perception. Toxins such as alcohol and chemotherapeutic agents are known causes of SFN, with research into other toxic aetiologies well underway. Pathologists are routinely exposed to a variety of organic solvents, such as xylene, acetone and methanol, which potentially lead to the development of SFN.
 Methods. We performed a retrospective review of all pathologists who were treated at the SFN clinic in our hospital between January 2020 and May 2021. Their clinical presentation, disease course, treatment and outcomes were described.
 Results. Three patients with SFN were identified. These patients experienced somatic symptoms of SFN such as burning pain, paraesthesia and autonomic symptoms including tachycardia and postural hypotension. Normal nerve conduction studies indicated intact large nerve fibres. Abnormal SFN tests including quantitative sensory testing, quantitative sudomotor axonal testing, and tilt table testing contributed to the diagnosis of SFN. Inflammatory and autoimmune markers were raised in two of the three pathologists. Toxicology screens performed later were negative, possibly indicating that blood solvent concentrations had decreased to undetectable levels over time. Administration of intravenous immunoglobulin (IVIg) resulted in an improvement in symptoms and functional outcomes.
 Conclusion. Chronic exposure to organic solvents in the routine job scope of pathologists may lead to the development of SFN. Awareness of this hazard is imperative in order to ensure occupational safety.

Influence of solid particles deposition on the initial atmospheric corrosion of 7B04 aluminum alloy

The influence of the deposition of three different particles (NaCl, C and SiO2) on the initial atmospheric corrosion of 7B04 aluminum alloy was investigated via laboratory exposure testing, environmental scanning electron microscope (E-SEM), energy dispersive X-ray spectroscopy (EDS), and scanning Kelvin probe (SKP). The results showed that the deposition of NaCl had a significant acceleration effect on the initial corrosion of 7B04 aluminum alloy and resulted in the occurrence of localized corrosion on sample surface. Because of its capillary condensation effect, SiO2 could absorb the vapor in humid environment to form a local water-rich area around the particles which could promote the corrosion of 7B04 aluminum alloy. C had basically no effect on the corrosion of 7B04 aluminum alloy.

Uptake of microplastics by the snakelocks anemone (Anemonia viridis) is commonplace across environmental conditions

Microplastics (<1 mm) are ubiquitous in our oceans and widely acknowledged as concerning contaminants due to the multi-faceted threats they exert on marine organisms and ecosystems. Anthozoans, including sea anemones and corals, are particularly at risk of microplastic uptake due to their proximity to the coastline, non-selective feeding mechanisms and sedentary nature. Here, the common snakelocks anemone (Anemonia viridis) was used to generate understanding of microplastic uptake in the relatively understudied Anthozoa class. A series of microplastic exposure and multi-stressor experiments were performed to examine particle shape and size selectivity, and to test for the influence of food availability and temperature on microplastic uptake. All A. viridis individuals were found to readily take up microplastics (mean 142.1 ± 83.4 particles per gram of tissue) but exhibited limited preference between different particle shapes and sizes (n = 32). Closer examination identified that uptake involved both ingestion and external tissue adhesion, where microplastics were trapped in secreted mucus. Microplastic uptake in A. viridis was not influenced by the presence of food or elevated water temperature (n = 40). Furthermore, environmental sampling was performed to investigate microplastic uptake in A. viridis (n = 8) on the coast of southwest England, with a mean of 17.5 ± 4.0 particles taken up per individual. Fibres represented the majority of particles (91%) followed by fragments (9%), with 87% either clear, blue or black in colour. FTIR analysis identified 70% of the particles as anthropogenic cellulosic or plastic polymers. Thus, this study provides evidence of microplastic uptake by A. viridis in both laboratory exposures experiments and in the marine environment. These findings support recent literature suggesting that external adhesion may be the primary mechanism in which anthozoans capture microplastics from the water column and highlights the potential role anemones can play as environmental microplastic bioindicators.

Detection of microplastics in human lung tissue using μFTIR spectroscopy

Airborne microplastics (MPs) have been sampled globally, and their concentration is known to increase in areas of high human population and activity, especially indoors. Respiratory symptoms and disease following exposure to occupational levels of MPs within industry settings have also been reported. It remains to be seen whether MPs from the environment can be inhaled, deposited and accumulated within the human lungs. This study analysed digested human lung tissue samples (n = 13) using μFTIR spectroscopy (size limitation of 3 μm) to detect and characterise any MPs present. In total, 39 MPs were identified within 11 of the 13 lung tissue samples with an average of 1.42 ± 1.50 MP/g of tissue (expressed as 0.69 ± 0.84 MP/g after background subtraction adjustments). The MP levels within tissue samples were significantly higher than those identified within combined procedural/laboratory blanks (n = 9 MPs, with a mean ± SD of 0.53 ± 1.07, p = 0.001). Of the MPs detected, 12 polymer types were identified with polypropylene, PP (23%), polyethylene terephthalate, PET (18%) and resin (15%) the most abundant. MPs (unadjusted) were identified within all regions of the lung categorised as upper (0.80 ± 0.96 MP/g), middle/lingular (0.41 ± 0.37 MP/g), and with significantly higher levels detected in the lower (3.12 ± 1.30 MP/g) region compared with the upper (p = 0.026) and mid (p = 0.038) lung regions. After subtracting blanks, these levels became 0.23 ± 0.28, 0.33 ± 0.37 and 1.65 ± 0.88 MP/g respectively. The study demonstrates the highest level of contamination control and reports unadjusted values alongside different contamination adjustment techniques. These results support inhalation as a route of exposure for environmental MPs, and this characterisation of types and levels can now inform realistic conditions for laboratory exposure experiments, with the aim of determining health impacts.

Monitoring Laboratory Occupational Exposures to Burkholderia pseudomallei.

Burkholderia pseudomallei is a Tier 1 overlap select agent and subject to the select agent regulations (42 CFR §73 and 9 CFR §121). It is a gram-negative, motile, soil saprophyte, and the etiologic agent of melioidosis. B. pseudomallei infection can produce systemic illness and can be fatal in the absence of appropriate treatment. Laboratory exposures involving this organism may occur when appropriate containment measures are not employed. Current disease treatment inadequacies and the risk factors associated with melioidosis make this an agent of primary concern in research, commercial, and clinical laboratory environments. This study presents data reported to Centers for Disease Control and Prevention (CDC), Division of Select Agents and Toxins for releases involving B. pseudomallei in 2017-2019 that occurred in Biosafety Level (BSL)-2 and BSL-3 laboratories. Fifty-one Animal and Plant Health Inspection Service (APHIS)/CDC Form 3 release reports led to the medical surveillance of 275 individuals. Entities offered post-exposure prophylaxis to ∼76% of the individuals impacted in the presented events. Laboratory safety can be improved by implementing appropriate safety precautions to minimize exposures. Most of the incidents discussed in this evidence-based report occurred during work conducted in the absence of primary containment. None of the releases resulted in illness, death, or transmission to or among workers, nor was there transmission outside of a laboratory into the surrounding environment or community. Effective risk assessment and management strategies coupled with standard and special microbiological policies and procedures can result in reduced exposures and improved safety at facilities.

Effects of microplastics (PVC, PMMA) on the mussel Semimytilus algosus differ only at high concentrations from those of natural microparticles (clay, celite)

Laboratory exposure studies allow to investigate the impact of microplastics on marine biota, but commonly lack a procedural control, i.e. assessing the effects of natural microparticles. In two experiments with the mussel Semimytilus algosus, we compared the effects of clay vs. polyvinyl chloride (PVC) and celite vs. polymethyl-methacrylate (PMMA), respectively, at concentrations of 1.5, 15 and 150 mg l−1. After more than 60 days, no effects on respiration and clearance rates, mortality and byssus strength were observed. However, in mussels exposed to PVC the Body Condition Index was 34% lower at 150 mg l−1 than at 1.5 mg l−1. Furthermore, at 15 mg l−1, mussels exposed to microplastics produced over 40% less byssus than those exposed to natural microparticles. This suggests that mussels react differently to natural microparticles and to microplastics, but only at high particle loads that exceed current environmental microplastic concentrations by orders of magnitude.

The Effects of Various Organic and Inorganic Fertilizers on the Density of Entomopathogenic Nematodes Symbiont

Entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora and their bacterial symbionts Xenorhabdus nematophila and Photorhabdus luminescens (P. luminescens), represent a specific agricultural niche. The successful integration of entomopathogenic nematodes (EPN) as regular use biological control agents require specific knowledge and understanding of the adaptation and establishment of applied biological control agents in agricultural ecosystems. For many years, the pest management capabilities of these pathogenic partnerships have been implemented in biological control settings. In this study, ten fertilizers were examined to explore the effects of nitrogen, phosphorus, and potassium (NPK) on the production of entomopathogenic bacteria Xenorhabdus nematophila and Photorhabdus luminescens. Laboratory exposure to fertilizer concentrations (0.5-2.5%) was used to determine the production of each bacterial species. Results conclude that P. luminescens are generally more sensitive to fertilizer than X. nematophila. Moreover, fertilizers containing high nitrogen suppressed bacterial densities more readily than those with lesser amounts. This paper summarizes the effects of the three important nutrients found in various concentrations of organic and inorganic fertilizers on entomopathogenic bacteria production.

Evidence for Negative Impacts on Terrestrial Salamanders following Invasive Plant Removal

Invasive species are widely believed to be a major threat to biodiversity. Therefore, invasive species control is a common practice among land managers. However, the impacts of invasive species control on nontarget organisms are often unknown. To examine the impact of invasive plant removal on a functionally important, but often overlooked, group of organisms, we carried out a field experiment focusing on terrestrial salamanders. Using coverboards, we monitored the occurrence of terrestrial salamanders (primarily Northern Ravine Salamanders, Plethodon electromorphus) in forest plots where invasive plants had been experimentally removed compared with control plots where removal did not occur. We replicated this design at three study sites and sampled coverboards over 3 yr (2016–2018; 2,187 sampling events). We also undertook a laboratory experiment exposing Northern Two-Lined Salamanders (Eurycea bislineata) to native and invasive plant root extracts compared with a plain water control. Results from occupancy modeling and other analytical techniques indicated strongly reduced occupancy of P. electromorphus in plots where invasive plants were removed, compared with controls. This pattern varied among study sites but was strongest at the most heavily invaded sites. Results from the laboratory exposure study showed no significant differences in response to root extracts from native versus invasive plants. Together, these data suggest that some terrestrial salamanders may not be negatively impacted by invasive plants and that invasive plant removal, when not accompanied by native plant restoration, may have unanticipated negative effects on terrestrial salamander populations.

Behaviors and trophodynamics of o,p′-dichlorodiphenyltrichloroethane (o,p′-DDT) in the aquatic food web: Comparison with p,p′-DDT

The broad-spectrum insecticide p,p′-dichlorodiphenyltrichloroethane (p,p′-DDT) has been banned in most countries since the 1970s on account of its environmental persistence as well as the high biomagnification of its major metabolite 1,1-dichloro-2,2-bis(4-chorophenyl)ethylene (p,p′-DDE). However, the information on the bioaccumulation and behavior of p,p′-DDTs in aquatic organisms is lacking. In this study, all 6 DDT isomers were detected in biota from the food web of the Liaodong Bay, China, and the total concentrations of DDT isomers in Chinese anchovy (Thrissa kammalensis) and Japanese Spanish mackerel (Scomberomrus niphonius) were 223 ± 42 ng/g ww and 242 ± 70 ng/g ww, respectively. In biota, o,p′-DDD dominated among the o,p′-isomers (80.5 ± 17.3%), while p,p′-DDE dominated among the p,p′-isomers (61.8 ± 15.2%). Contrastingly, sediment from the Liaodong Bay contained similar proportions of o,p′-DDT and p,p′-DDTs, suggesting an isomer-specific metabolism of the compounds in biota. A well-controlled laboratory exposure experiment with Japanese medaka (Oryzias latipes) demonstrated that o,p′-DDT was more difficult to metabolize to o,p′-DDE compared with that of p,p′-DDT. Significantly positive regressions were found between trophic levels and lipid equivalent concentrations for both o,p′-DDT and o,p′-DDD, and the trophic magnification factors (TMFs) were estimated as 12.3 and 9.12 (p < 0.05), respectively. The TMFs of o,p′-DDT and o,p′-DDD in the aquatic food web were higher than p,p′-DDT (7.76), p,p′-DDD (4.17), and p,p′-DDE (3.39), which may be explained by the isomer-specific metabolism differences in biota.

Relevant and Realistic Assessments of Micro- and Nanoplastics in the Environment.

Plastic pollution remains a global anthropogenic threat due to its universal use in our daily life and ubiquitous presence in all environmental compartments (Geyer et al. 2017). Despite large and increased research efforts within this field (Sorensen and Jovanović 2021), clear guidelines on safe concentrations, thresholds and ultimately adverse effects for environmental health are lacking (Toussaint B et al 2019.). This can be largely attributed to the fact that micro- and nanoplastics are, unlike other groups of contaminants, an extremely heterogeneous group. They vary in shape, size and chemical composition and each of these parameters may influence the behaviour, fate, transport and effects. In the past, most studies have focussed on homogenous pristine micro- or nanoplastics in a defined shape and size class (Paul-Pont et al. 2018). While these studies certainly have value in unravelling modes of action and mechanisms of toxicity, the gap between laboratory and natural exposure is large and these studies remain far from environmental reality. Micro- and nanoplastics can actually be seen as a mixture of different types of particles that can further interact with the environment. These interactions include environmental weathering, absorption/desorption of chemicals and additives (Lusher et al. 2017; Koelmans et al. 2016) and biofilm formation which may lead to pathogen transfer (Huang et al. 2021). At present, more and more studies are addressing these issues and the current knowledge gaps are primarily related to small micro- and nanoplastics and their fate, transport and ultimately environmental risk. This is can be partly attributed to analytical challenges in terms of extraction, quantification and characterization in complex environmental matrices where only recently significant progress was made (Silva et al 2018). This special issues integrates publications that will contribute scientific knowledge to (1) improved analytical methodologies for complex environmental matrices, (2) effect assessments of micro- and nanoplastics accounting for physico-chemical properties as well as environmental interactions and (3) integrated perspectives and analyses on risk assessment. This article is protected by copyright. All rights reserved.

Effects of Microplastics on the Mineral Elements Absorption and Accumulation in Hydroponic Rice Seedlings (Oryza sativa L.).

Environmental pollution caused by microplastics (MPs) have become a non-negligible environmental problem and come into our notice recently. Herein, the nutrient elemental signature (ionome) of rice seedlings exposed to four levels of polyethylene microplastics (PE-MPs), and was analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) or mass spectroscopy (ICP-MS) to determine the relationship between ionome and MPs. After 21days of laboratory exposure, no shoots growth difference has shown among any doses of PE-MPs treatments, however, the roots growth was significantly inhibited after the medium and high doses of PE-MPs treatments. Further analysis showed that PE-MPs treatments could decrease the accumulation of one essential mineral element Mn and some non-essential mineral elements accumulation including As and Cd, while increase the accumulation of one essential mineral elements including Na in rice seedlings. This study is the first to document the variation of the rice seedlings ionome after exposing microplastics.

Evaluation of Applied Stress on Atmospheric Corrosion and Pitting Characteristics in 304L Stainless Steel

The effects of applied stress, ranging from tensile to compressive, on the atmospheric pitting corrosion behavior of 304L stainless steel (SS304L) were analyzed through accelerated atmospheric laboratory exposures and microelectrochemical cell analysis. After exposing the lateral surface of a SS304L four-point bend specimen to artificial seawater at 50°C and 35% relative humidity for 50 d, pitting characteristics were determined using optical profilometry and scanning electron microscopy. The SS304L microstructure was analyzed using electron backscatter diffraction. Additionally, localized electrochemical measurements were performed on a similar, unexposed, SS304L four-point bend bar to determine the effects of applied stress on corrosion susceptibility. Under the applied loads and the environment tested, the observed pitting characteristics showed no correlation with the applied stress (from 250 MPa to −250 MPa). Pitting depth, surface area, roundness, and distribution were found to be independent of location on the sample or applied stress. The lack of correlation between pitting statistics and applied stress was more likely due to the aggressive exposure environment, with a sea salt loading of 4 g/m2 chloride. The pitting characteristics observed were instead governed by the available cathode current and salt distribution, which are a function of sea salt loading, as well as pre-existing underlying microstructure. In microelectrochemical cell experiments performed in Cl− environments comparable to the atmospheric exposure and in environments containing orders of magnitude lower Cl− concentrations, effects of the applied stress on corrosion susceptibility were only apparent in open-circuit potential in low Cl− concentration solutions. Cl− concentration governed the current density and transpassive dissolution potential.

Thermal stress responses of the antipatharian Stichopathes sp. from the mesophotic reef of Mo'orea, French Polynesia

Antipatharians, also called black corals, are present in almost all oceans of the world, until extreme depths. In several regions, they aggregate in higher densities to form black coral beds that support diverse animal communities and create biodiversity hotspots. These recently discovered ecosystems are currently threatened by fishing activities and illegal harvesting for commercial purposes. Despite this, studies dedicated to the physiology of antipatharians are scarce and their responses to global change stressors have remained hardly explored since recently. Here, we present the first study on the physiological responses of a mesophotic antipatharian Stichopathes sp. (70–90 m) to thermal stress through a 16-d laboratory exposure (from 26 to 30.5 °C). Oxygen consumption measurements allowed identifying the physiological tipping point of Stichopathes sp. (Topt = 28.3 °C; 2.7 °C above mean ambient condition). Our results follow theoretical predictions as performances start to decrease beyond Topt, with lowered oxygen consumption rates, impairment of the healing capacities, increased probability of tissue necrosis and stress responses activated as a function of temperature (i.e. increase in mucocyte density and total antioxidant capacity). Altogether, our work indicates that Stichopathes sp. lives at suboptimal performances during the coldest months of the year, but also that it is likely to have low acclimatization capacity and a narrow thermal breadth.

Microplastics can alter phytoplankton community composition

Microplastic pollution is a growing concern globally due to the risks they may pose to ecological communities. Phytoplankton are key ecological community in aquatic ecosystems providing both energy to food webs and have critical roles in ecosystem functions such as carbon cycling. To date studies on how microplastics effect phytoplankton have largely been limited to laboratory exposure studies using monocultures of algae. It remains unknown how the structure of phytoplankton communities will be influenced by growing microplastic pollution. The aim of this study was to determine how different concentrations microplastic fibers influence phytoplankton community structure. Two six-day microcosm studies were conducted testing the response of the phytoplankton community to low, medium, and high microplastics concentrations on the Georges River, Australia. The results showed the highest concentrations of microplastics significantly altered the structure phytoplankton community. These differences were largely driven by increased abundances of cyanobacteria taxa Aphanocapsa and Pseudanabaena, and to a lesser extent reduced abundances of taxa including Crucigenia and Chlamydmonas. There were no significant differences between controls and the low and medium treatments in either experiment. The high concentrations used in this experiment whilst likely rare in the environment are environmentally relevant and equivalent to some of more polluted ecosystems. The results highlight the potential risk to food webs and ecosystem functioning through altering the dynamics of primary production and provide evidence for further study examining the response of ecological communities to microplastics in the environment.