Impact of polyethylene microplastics on coral Goniopora columna causing oxidative stress and histopathology damages

The comparative toxicity of biobased, modified biobased, biodegradable, and petrochemical-based microplastics on the brackish water flea Diaphanosoma celebensis

The escalating production and improper disposal of petrochemical-based plastics have led to a global pollution issue with microplastics (MPs), which pose a significant ecological threat. Biobased and biodegradable plastics are believed to mitigate plastic pollution. However, their environmental fate and toxicity remain poorly understood. This study compares the in vivo effects of different types of MPs, poly(butylene adipate-co-terephthalate) as a biodegradable plastic, polylactic acid (PLA) as a biobased plastic, β-cyclodextrin-grafted PLA as a modified biobased plastic, and low density polyethylene as the reference petrochemical-based plastic, on the key aquatic primary consumer Diaphanosoma celebensis. Exposure to MPs resulted in significant reproductive decline, with comparable effects observed irrespective of MP type or concentration. Exposure to MPs induced distinct responses in redox stress, with transcriptional profiling revealing differential gene expression patterns that indicate varied cellular responses to different types of MPs. ATP-binding cassette transporter activity assays demonstrated altered efflux activity, mainly in response to modified biobased and biodegradable MPs. Overall, this study highlights the comparable in vivo and in vitro effects of biobased, biodegradable, and petrochemical-based MPs on aquatic primary consumers, highlighting their potential ecological implications.

Northern coral triangle coral ciliates diseases and disease prevention: A first record

This study is the first to report ciliate infection on soft corals in the Northern Coral Triangle. Infected Briareum violacea will undergo tissue ulceration and death within a short period of time. This ciliate was identified as Scuticociliatia sp. through 18S rRNA gene identification. In this study, the body length of the ciliate was approximately 80-85 μm before parasitizing the B. violacea. After being parasitizing, the body length was approximately 200-250 μm, and the body width was 50 μm. Body size increased three times after parasitism. According to observations, ciliates will first parasitize the coral endoderm in the early stage of infection, and no ciliates were found in the ectoderm. Preliminary judgment suggests that it may invade the coral endoderm through the mouth for parasitism. After parasitism, the ciliate eats the coral tissue and zooxanthellae. The antioxidant enzymes SOD, CAT, and MDA of infected corals were significantly increased, which also means that the corals are in a stress response. Ciliates will eat the zooxanthellae in the coral body, resulting in a significant reduction in the number of zooxanthellae and chlorophyll a. To effectively prevent and treat this disease, Combretum indicum extract was used in this study. It is a tropical plant commonly used medicinally to treat roundworms, pinworms and parasitic diseases. The results showed that at a concentration of 1500-2500 ppm, Combretum indicum extract can be used to treat ciliates and can applied via medicinal bath therapy for long periods without causing coral stress reactions. The results of this study regarding coral disease prevention are in line with SDG 14 and promote the practical application of coral reef ecological sustainability and large-scale coral aquaculture.

Chronic effects of exposure to polyethylene microplastics may be mitigated at the expense of growth and photosynthesis in reef-building corals

The causes of the physiological effects of microplastic pollution, potentially harming reef-building corals, are unclear. Reasons might include increased energy demands for handling particles and immune reactions. This study is among the first assessing the effects of long-term microplastic exposure on coral physiology at realistic concentrations (200 polyethylene particles L-1). The coral species Acropora muricata, Pocillopora verrucosa, Porites lutea, and Heliopora coerulea were exposed to microplastics for 11 months, and energy reserves, metabolites, growth, and photosymbiont state were analyzed. Results showed an overall low impact on coral physiology, yet species-specific effects occurred. Specifically, H. coerulea exhibited reduced growth, P. lutea and A. muricata showed changes in photosynthetic efficiency, and A. muricata variations in taurine levels. These findings suggest that corals may possess compensatory mechanisms mitigating the effects of microplastics. However, realistic microplastic concentrations only occasionally affected corals. Yet, corals exposed to increasing pollution scenarios will likely experience more negative impacts.

Microplastics alter the leaf litter breakdown rates and the decomposer community in subtropical lentic microhabitats

Microplastics, pervasive pollutants in aquatic environments, have been primarily studied for their impact on marine ecosystems. However, their effects on freshwater systems, particularly in forested phytotelmata habitats, remain understudied in Subtropical systems. This research examines the influence of varying microplastic concentrations (0.0, 200, 2,000, 20,000, and 200,000 ppm) on leaf litter breakdown of Inga vera (in bags of 10 and 0.05 mm mesh) and the naturally associated invertebrate community occurring in forested phytotelmata. The study employs an experimental design with microplastic concentration treatments in artificial microcosms (buckets with 800 mL of rainwater) arranged in an area of Atlantic Rain Forest native vegetation of Subtropical systems. The results indicate that elevated concentrations of microplastics may enhance leaf litter breakdown (6-8%), irrespective of the bag mesh, attributed to heightened decomposer activity and biofilm formation. Consequently, this contributes to increased invertebrate richness (33-37%) and greater shredder abundance (21-37%). Indicator analysis revealed that Culicidae, Stratiomyidae, Chironomidae, Empididae, Planorbidae, and Ceratopogonidae were indicative of some microplastic concentrations. These findings underscore the significance of accounting for microplastics when evaluating the taxonomic and trophic characteristics of invertebrate communities, as well as the leaf breakdown process in Subtropical systems.

Microplastics inhibit the growth of endosymbiotic Symbiodinium tridacnidorum by altering photosynthesis and bacterial community

Microplastics, ubiquitous anthropogenic marine pollutants, represent potential threats to coral-Symbiodiniaceae relationships in global reef ecosystems. However, the mechanism underlying the impacts of polystyrene microplastics (PS-MPs) on Symbiodiniaceae remains poorly understood. In this study, the cytological, physiological, and microbial responses of Symbiodinium tridacnidorum, a representative Symbiodiniaceae species, to varying concentrations of PS-MPs (0, 5, 50, 100, and 200 mg L-1) were investigated. The results revealed that microplastic exposure inhibited cell division, resulting in reduced cell density compared to control group. Furthermore, algal photosynthetic activity, as indicated by chlorophyll content, Fv/Fm, and net photosynthetic rate, declined with increasing microplastic concentration up to 50 mg L-1. Notably, elevated levels of microplastics (100 and 200 mg L-1) prompted a significant increase in cell size in S. tridacnidorum. Transmission electron microscopy and fluorescence microscopy indicated that hetero-aggregation was formed between high levels of PS-MPs and algal cells, ultimately causing damage to S. tridacnidorum. Moreover, the impact of PS-MPs exposure on the bacterial community associated with S. tridacnidorum was investigated. The results showed a reduction in alpha diversity of the bacterial community in groups exposed to 50, 100, and 200 mg L-1 of microplastics compared to those treated with 0 and 5 mg L-1. Additionally, the relative abundance of Marinobacter, Marivita, and Filomicrobium significantly increased, while Algiphilus and norank Nannocystaceae declined after microplastic exposure. These findings suggest that MPs can inhibit the growth of S. tridacnidorum and alter the associated bacterial community, posing a potential serious threat to coral symbiosis involving S. tridacnidorum.

Physical and cellular impact of environmentally relevant microplastic exposure on thermally challenged Pocillopora damicornis (Cnidaria, Scleractinia)

Microplastic pollution is an increasing threat to coral reefs, which are already strongly challenged by climate change-related heat stress. Although it is known that scleractinian corals can ingest microplastic, little is known about their egestion and how microplastic exposure may impair corals at physiological and cellular levels. In addition, the effects of microplastic pollution at current environmental concentration have been little investigated to date, particularly in corals already impacted by heat stress. In this study, the combined effects of these environmental threats on Pocillopora damicornis were investigated from a physical and cellular perspective. Colonies were exposed to three concentrations of polyethylene microplastic beads (no microplastic beads: [No MP], 1 mg/L: [Low MP]; 10 mg/L: [High MP]), and two different temperatures (25 °C and 30 °C) for 72 h. No visual signs of stress in corals, such as abnormal mucus production and polyp extroflection, were recorded. At [Low MP], beads adhered to colonies were ingested but were also egested. Moreover, thermally stressed colonies showed a lower adhesion and higher egestion of microplastic beads. Coral bleaching was observed with an increase in temperature and microplastic bead concentration, as indicated by a general decrease in chlorophyll concentration and Symbiodiniaceae density. An increase in lipid peroxidation was measured in colonies exposed to [Low MP] and [High MP] and an up-regulation of stress response gene hsp70 was observed due to the synergistic interaction of both stressors. Overall, our findings showed that heat stress still represents the main threat to P. damicornis, while the effect of microplastics on coral health and physiology may be minor, especially at control temperature. However, microplastics could exacerbate the effect of thermal stress on cellular homeostasis, even at [Low MP]. While reducing ocean warming is critical for preserving coral reefs, effective management of emerging threats like microplastic pollution is equally essential.

Combined toxicity of microplastics and copper on Goniopora columns

As microplastics (MP) become ubiquitous, their interactions with heavy metals threatens the coral ecosystem. This study aimed to assess the combined toxicity of MP and copper (Cu) in the environment of coral. Goniopora columna was exposed to polyethylene microplastics (PE-MP) combined with Cu2+ at 10, 20, 50, 100, and 300 μg/L for 7 days. Polyp length and adaptability were recorded daily, and coral samples were collected at 1, 3, 5, and 7 days to analyse zooxanthellae density and antioxidant activity. Tissue observations and the analysis of MP and Cu2+ accumulation were conducted on the 7th day. After 1 day of exposure, PE-MP combined with different concentrations of Cu2+ significantly decreased polyp length and adaptability compared with PE-MP alone. Simultaneously, a significant increase in malondialdehyde (MDA) content, lead to coral oxidative stress, which was a combined effect with PE-MP. After 3 days of exposure, PE-MP combined with Cu2+ at >50 μg/L significantly reduced zooxanthellae density, damaging the coral's symbiotic relationship. In antioxidant enzyme activity, superoxide dismutase (SOD) activity decreased significantly after 1 day of exposure. After 3 days of exposure, glutathione peroxidase (GPx) activity significantly increased with Cu2+ at >20 μg/L. After 5 days of exposure, PE-MP combined with different concentrations of Cu2+ significantly reduced catalase (CAT), glutathione (GSH), and glutathione transferase (GST) activity, disrupting the antioxidant enzyme system, and acting antagonistically to PE-MP alone. Tissue observations revealed that the PE-MP combined with Cu2+ at >50 μg/L caused severe mesenteric atrophy, vacuolar, and Cu2+ accumulation in the coral mesenteric compared with PE-MP alone. The results suggest that combined exposure of PE-MP and copper leads to more severe oxidative stress, disruption antioxidant enzyme system, tissue damage, and Cu2+ accumulation, resulting in a significant maladaptation of corals to the environment.

Occurrence of phthalic acid esters (PAEs) and active pharmaceutical ingredients (APIs) in key species of anthozoans in Mediterranean Sea

The Mediterranean Sea's biodiversity is declining due to climate change and human activities, with plastics and emerging contaminants (ECs) posing significant threats. This study assessed phthalic acid esters (PAEs) and active pharmaceutical ingredients (APIs) occurrence in four anthozoan species (Cladocora caespitosa, Eunicella cavolini, Madracis pharensis, Parazoanthus axinellae) using solid phase microextraction (SPME) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). All specimens were contaminated with at least one contaminant, reaching maximum values of 57.3 ng/g for the ∑PAEs and 64.2 ng/g (wet weight) for ∑APIs, with dibutyl phthalate and Ketoprofen being the most abundant. P. axinellae was the most contaminated species, indicating higher susceptibility to bioaccumulation, while the other three species showed two-fold lower concentrations. Moreover, the potential adverse effects of these contaminants on anthozoans have been discussed. Investigating the impact of PAEs and APIs on these species is crucial, given their key role in the Mediterranean benthic communities.

Common types of microdebris affect the physiology of reef-building corals

Marine debris, particularly microdebris (< 1 mm) poses a potential threat to marine life, including reef-building corals. While previous research has mainly focused on the impact of single polymer microplastics, the effects of natural microdebris, composed of a mixture of materials, have not been explored. Therefore, this study aimed to assess the effects of different microdebris, originating from major sources of pollution, on reef-building corals. For this, we exposed two scleractinian coral species, Pocillopora verrucosa and Stylophora pistillata, known to frequently ingest microplastics, to four types of microdebris in an 8-week laboratory experiment: fragmented environmental plastic debris, artificial fibers from clothing, residues from the automobile sector consisting of tire wear, brake abrasion, and varnish flakes, a single polymer microplastic treatment consisting of polyethylene particles, and a microdebris-free control treatment. Specifically, we (I) compared the effects of the different microdebris on coral growth, necrosis, and photosynthesis, (II) investigated the difference between the microdebris mixtures and the exposure to the single polymer treatment, and (III) identified potential mechanisms causing species-specific effects by contrasting the feeding responses of the two coral species on microdebris and natural food. We show that the fibers and tire wear had the strongest effects on coral physiology, with P. verrucosa being more affected than S. pistillata. Both species showed increased volume growth in response to the microdebris treatments, accompanied by decreased calcification in P. verrucosa. Photosynthetic efficiency of the symbionts was enhanced in both species. The species-specific physiological responses might be attributed to feeding reactions, with P. verrucosa responding significantly more often to microdebris than S. pistillata. These findings highlight the effect of different microdebris on coral physiology and the need for future studies to use particle mixtures to better mimic naturally occurring microdebris and assess its effect on corals in more detail.

Understanding the mechanistic roles of microplastics combined with heavy metals in regulating ferroptosis: Adding new paradigms regarding the links with diseases

As a new type of pollutant, microplastics (MPs) commonly exist in today's ecosystems, causing damage to the ecological environment and the health of biological organisms, including human beings. MPs can function as carriers of heavy metals (HMs) to aggravate the enrichment of HMs in important organs of organisms, posing a great threat to health. Ferroptosis, a novel process for the regulation of nonapoptotic cell death, has been shown to be closely related to the occurrence and processes of MPs and HMs in diseases. In recent years, some HMs, such as cadmium (Cd), iron (Fe), arsenic (As) and copper (Cu), have been proven to induce ferroptosis. MPs can function as carriers of HMs to aggravate damage to the body. This damage involves oxidative stress, mitochondrial dysfunction, lipid peroxidation (LPO), inflammation, endoplasmic reticulum stress (ERS) and so on. Therefore, ferroptosis has great potential as a therapeutic target for diseases induced by MPs combined with HMs. This paper systematically reviews the potential effects and regulatory mechanisms of MPs and HMs in the process of ferroptosis, focusing on the mitochondrial damage, Fe accumulation, LPO, ERS and inflammation caused by MPs and HMs that affect the regulatory mechanism of ferroptosis, providing new insights for research on regulating drugs and for the development of ferroptosis-targeting therapy for Alzheimer's disease, Parkinson's disease, cancer and cardiovascular disease.

Microplastics elicit an immune-agitative state in coral

Microplastic pollution in the ocean is a major problem, as its pervasiveness elicits concerns the health impacts microplastics may have on marine life (such as reef-building corals). As a primary endpoint, the organismal lipidome can define the weakening of fitness and reveal the physiological context of adverse health effects in organisms. To gain insight into the effects of microplastics on coral health, lipid profiling was performed via an untargeted lipidomic approach on the coral Turbinaria mesenterina exposed to ~10 μm polystyrene microparticles for 10 days. Considerable microplastic accumulation and obvious effects relating with immune activation were observed in the coral treated with a near environmentally relevant concentration of microplastics (10 μg/L); however, these effects were not evident in the high level (100 μg/L) treatment group. In particular, increased levels of membrane lipids with 20:4 and 22:6 fatty acid chains reallocated from the triacylglycerol pool were observed in coral host cells and symbiotic algae, respectively, which could upregulate immune activity and realign symbiotic communication in coral. High levels of polyunsaturation can sensitize the coral cell membrane to lipid peroxidation and increase cell death, which is of greater concern; additionally, the photoprotective capacity of symbiotic algae was compromised. As a result, coral physiological functions were altered. These results show that, realistic levels of microplastic pollution can affect coral health and should be a concern.

Biomarkers of oxidative stress, inflammation, and genotoxicity to assess exposure to micro- and nanoplastics. A literature review

The increased awareness about possible health effects arising from micro- and nanoplastics (MNPs) pollution is driving a huge amount of studies. Many international efforts are in place to better understand and characterize the hazard of MNPs present in the environment. The literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology in two different databases (PubMed and Embase). The selection of articles was carried out blind, screening titles and abstracts according to inclusion and exclusion criteria. In general, these studies rely on the methodology already in use for assessing hazard from nanomaterials and particles of concern. However, only a limited number of studies have so far directly measured human exposure to MNPs and examined the relationship between such exposure and its impact on human health. This review aims to provide an overview of the current state of research on biomarkers of oxidative stress, inflammation, and genotoxicity that have been explored in relation to MNPs exposure, using human, cellular, animal, and plant models. Both in-vitro and in-vivo models suggest an increased level of oxidative stress and inflammation as the main mechanism of action (MOA) leading to adverse effects such as chronic inflammation, immunotoxicity and genotoxicity. With the identification of such biological endpoints, representing critical key initiating events (KIEs) towards adaptive or adverse outcomes, it is possible to identify a panel of surrogate biomarkers to be applied and validated especially in occupational settings, where higher levels of exposure may occur.

Unveiling the hidden threat of microplastics to coral reefs in remote South Atlantic islands

The widespread presence of marine microplastics (< 5 mm) is a significant concern, as it may harm marine biodiversity and ocean ecosystems. Corals' capacity to ingest microplastics has emerged as a significant threat to reef ecosystems, owing to the detrimental physiological and ecological effects it can trigger. The extent of the impact of microplastics on Brazilian corals remains unclear and this study aimed to investigate its distribution and characteristics in four coral species: Favia gravida, Mussismilia hispida, Montastrea cavernosa, and Siderastrea stellata, found in the Trindade and Martim Vaz Islands - the most isolated archipelago of Brazil, located about 1200 km (680 miles) east of the coast. This study aims to reveal the extent of microplastic distribution in the coral reef environment, assess the amount of microplastics in different coral species, and compare each species' capacity to adhere and accumulate microplastics. A high concentration of ingested and adhered microplastics was detected in all coral species evaluated in the present study. No significant differences were observed in the sampling points which indicates that although the sampling points are located at different distances from the coast, the microplastic pollution is equally distributed in the region. Polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), poly(methyl methacrylate) (PMMA), Rayon, and Nylon particles were detected, with a predominance of PE (45.5 %). No significant differences in microplastic concentration were detected among the various species and locations studied. Our research presents findings that demonstrate the extensive occurrence of microplastic contamination in coral colonies located on remote islands.

Physiological and biochemical responses of soft coral Sarcophyton trocheliophorum to doxycycline hydrochloride exposure

In light of the rapid expansion of the marine aquaculture industry, there has been widespread and irregular usage of aquatic drugs to combat biological diseases, which significantly impact the neighboring aquatic ecosystems. This study delves into the impact of the antibiotic aquatic drug known as doxycycline hydrochloride (DOX) on offshore soft corals, providing valuable data for the responsible use and management of aquatic drugs. In this investigation, we subjected Sarcophyton trocheliophorum to acute exposure to varying concentrations of DOX (0, 1, 5, and 10 mg L-1). We meticulously assessed critical parameters and observed alterations in protein levels, superoxide dismutase (SOD) activity, catalase (CAT) activity, lipid peroxidation (LPO), malondialdehyde (MDA) levels, Acid phosphatase (ACP) activity, alkaline phosphatase (AKP) activity, glutathione (GSH) concentration, glutathione S-transferase (GST) activity, glutathione Peroxidase (GSH-Px) activity, zooxanthellae density, and chlorophyll content. Our findings reveal that in the presence of DOX-induced environmental stress, there is a significant increase in LPO, MDA, chlorophyll, carotenoid levels, and the activities of ACP, GST, and GSH-Px in soft corals. Simultaneously, there is a noteworthy decrease in zooxanthellae density. Additionally, the protein concentration and SOD activity in soft corals experience substantial reduction when exposed to 5 mg L-1 DOX. Notably, CAT activity varies significantly in environments with 1 and 10 mg L-1 DOX. Moreover, these conditions exhibit a discernible influence on AKP activity, GSH content, and chlorophyll levels. These findings suggest that DOX exposure carries the potential for toxicity in aquaculture settings, affecting protein synthesis in soft corals and influencing oxidative stress, lipid peroxidation, immunity, and detoxification processes within these organisms. There is also a risk of compromising the coral defense system, potentially leading to coral bleaching. Furthermore, this study underscores the significant impact on photosynthesis, growth, and the metabolic dynamics of the coral-zooxanthellae symbiotic system. Consequently, our research offers vital insights into the mortality and bleaching effects of aquatic drugs on marine corals, offering a foundation for the prudent use and management of such substances.

Microplastic as an invisible threat to the coral reefs: Sources, toxicity mechanisms, policy intervention, and the way forward

Microplastic (MP) pollution waste is a global macro problem, and research on MP contamination has been done in marine, freshwater, and terrestrial ecosystems. Preventing MP pollution from hurting them is essential to maintaining coral reefs' ecological and economic benefits. However, the public and scientific communities must pay more attention to MP research on the coral reef regions' distribution, effects, mechanisms, and policy evaluations. Therefore, this review summarizes the global MP distribution and source within the coral reefs. Current knowledge extends the impacts of MP on coral reefs, existing policy, and further recommendations to mitigate MPs contamination on corals are critically analyzed. Furthermore, mechanisms of MP on coral and human health are also highlighted to pinpoint research gaps and potential future studies. Given the escalating plastic usage and the prevalence of coral bleaching globally, there is a pressing need to prioritize research efforts on marine MPs that concentrate on critical coral reef areas. Such investigations should encompass an extensive and crucial understanding of the distribution, destiny, and effects of the MPs on human and coral health and the potential hazards of those MPs from an ecological viewpoint.

Presence, variation, and potential ecological impact of microplastics in the largest shallow lake of Central Europe

The presence of microplastics (MPs) in the global ecosystem has generated a rapidly growing concern worldwide. Although their presence in the marine environment has been well-studied, much less data are available on their abundance in freshwaters. MPs alone and in combination with different chemicals has been shown to cause acute and chronic effects on algae and aquatic invertebrate and vertebrate species at different biological levels. However, the combined ecotoxicological effects of MPs with different chemicals on aquatic organisms are still understudied in many species and the reported data are often controversial. In the present study, we investigated, for the first time, the presence of MPs in Lake Balaton, which is the largest shallow lake of Central Europe and an important summer holiday destination. Moreover, we exposed neonates of the well-established ecotoxicological model organism Daphnia magna to different MPs (polystyrene [3 μm] or polyethylene [≤ 100 μm]) alone and in combination with three progestogen compounds (progesterone, drospirenone, levonorgestrel) at an environmentally relevant concentration (10 ng L^-1) for 21 days. The presence of 7 polymer types of MPs in the size range of 50-100 μm was detected in Lake Balaton. Similarly to the global trends, polypropylene and polyethylene MPs were the most common types of polymer. The calculated polymer-independent average particle number was 5.5 particles m^-3 (size range: 50 μm - 100 μm) which represents the values detected in other European lakes. Our ecotoxicological experiments confirmed that MPs and progestogens can affect D. magna at the behavioral (body size and reproduction) and biochemical (detoxification-related enzyme activity) levels. The joint effects were negligible. The presence of MPs may lead to reduced fitness in the aquatic biota in freshwaters such as Lake Balaton, however, the potential threat of MPs as vectors for progestogens may be limited.

Maternal Zearalenone Exposure Affects Gut Microbiota and Follicular Development in Suckled Offspring

Zearalenone (ZEN) is a mycotoxin that is widely present in feed and agricultural products. Studies have demonstrated that ZEN, as a type of estrogen analogue, can significantly affect the female reproductive system. Breast milk is the best nutrient for infant growth and development, but it is still unknown whether ZEN influences the fertility of offspring through suckling. In this study, we collected fecal and ovarian tissue from neonatal female offspring, whose mothers were exposed to ZEN for 21 days, and explored the effects of maternal ZEN exposure on intestinal microecology and follicular development in the mouse using 16S rRNA amplicon sequencing technology. Our findings suggested that maternal ZEN exposure significantly diminished ovarian reserve, increased apoptosis of ovarian granulosa cell (GC), and impacted the developmental competence of oocytes in lactating offspring. In addition, the results of 16S rRNA sequencing showed that the abundance of gut microbiota in offspring was significantly changed, including Bacteroidetes, Proteobacteria, and Firmicutes. This leads to alterations of glutathione metabolism and the expression of antioxidant enzymes in ovaries. In summary, our findings supported a potential relationship between gut microbiota and abnormal ovarian development caused by ZEN, which offers novel insights for therapeutic strategies for reproductive disorders induced by ZEN exposure.

Effects of environmentally relevant concentrations of microplastics on amphipods

Lack of microplastics (MP) toxicity studies involving environmentally relevant concentrations and exposure times is concerning. Here we analyzed the potential adverse effects of low density polyethylene (LDPE) MP at environmentally relevant concentration in sub-chronic exposure to two amphipods Gmelinoides fasciatus and Gammarus lacustris, species that naturally compete with each other for their habitats. 14-day exposure to 2 μg/L (8 particles/L corresponding to low exposure) and 2 mg/L (∼8400 particles/L, corresponding to high exposure) of 53-100 μm LDPE MP were used to assess ingestion and egestion of MP, evaluate its effects on amphipod mortality, swimming ability and oxidative stress level. Both amphipod species were effectively ingesting and egesting LDPE MP. On the average, 0.8 and 2.5 MP particles were identified in the intestines of each amphipod exposed to 2 μg/L and 2 mg/L LDPE MP, respectively. Therefore, intestinal MP after 14-day exposure did not fully reflect the differences in LDPE MP exposure concentrations. Increased mortality of both amphipods was observed at 2 mg/L LDPE MP and in case of G. lacustris also at 2 μg/L exposure. The effect of LDPE on swimming activity was observed only in case of G. fasciatus. Oxidative stress marker enzymes SOD, GPx and reduced glutathione GSH varied according to amphipod species and LDPE MP concentration. In general G. lacustris was more sensitive towards LDPE MP induced oxidative stress. Overall, the results suggested that in MP polluted environments, G. lacustris may lose its already naturally low competitiveness and become overcompeted by other more resistant species. The fact that in the sub-chronic foodborne exposure to environmentally relevant and higher LDPE MP concentrations all the observed toxicological endpoints were affected refers to the potential of MP to affect and disrupt aquatic communities in the longer perspective.

Ecological responses of coral reef to polyethylene microplastics in community structure and extracellular polymeric substances

The relationships and interactions between extracellular polymeric substances (EPS) and microplastics (MPs) in coral reef ecosystems were symmetrically investigated. The current study aims to investigate the responses of scleractinian coral (Goniopora columna) to exposure of model MPs, exemplified by polyethylene (PE), in the size range of 40-48 μm as affected by MPs concentration of MP in the range between 0 and 300 mg L^-1 for 14 days. The structure of EPS-associated microbial community was studied using a series of techniques including high-throughput sequencing of 16 S rRNA, transmission electron microscopy (TEM), hydrodynamic diameter, surface charge (via zeta potential), X-ray diffraction (XRD), attenuated total reflectance‒Fourier transform infrared (ATR‒FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and fluorescence excitation-emission matrix (FEEM) spectroscopy. Microbial interactions between PE-MPs and coral caused aggregation and formation of EPS matrix, which resulted in increase and decrease in the relative abundance of Donghicola (Proteobacteria phylum) and Marivita (Proteobacteria phylum) in PE-MP-associated EPS, respectively. Particle size, electrostatic interactions, and complexation with the functional groups of the EPS-based matrix affected the humification index. FEEM spectroscopy analyses suggested the presence of humic- and fulvic-like fluorophores in EPS and dissolved organic matter (DOM) in PE-MP-derived DOM. The findings provided insights into the potential environmental implications of coral-based EPS and co-existing microbial assemblages due to EPS-PE-MP-microbiome interactions throughout the dynamic PE-MP exposure process.

Plastics in the environment as potential threat to life: an overview

Plastics have become inevitable for human beings in their daily life. Million tons of plastic waste is entering in oceans, soil, freshwater, and sediments. Invasion of plastics in different ecosystems is causing severe problems to inhabitants. Wild animals such as seabirds, fishes, crustaceans, and other invertebrates are mostly effected by plastic entanglements and organic pollutants absorbed and carried by plastics/microplastics. Plastics can also be potentially harmful to human beings and other mammals. Keeping in view the possible harms of plastics, some mitigation strategies must be adopted which may include the use of bioplastics and some natural polymers such as squid-ring teeth protein. This review focuses on the possible sources of intrusion and fate of plastics in different ecosystems, their potential deleterious effects on wildlife, and the measures that can be taken to minimize and avoid the plastic use.