The integrated biomarker response revisited: optimization to avoid misuse

Biomarker responsiveness in Norwegian Sea mussels, Mytilus edulis, exposed at low temperatures to aqueous fractions of crude oil alone and combined with dispersant

Biological effects of aqueous fractions of a crude oil, alone or in combination with dispersant, were investigated in mussels, Mytilus edulis, exposed at three temperatures (5, 10 and 15 °C). Polycyclic aromatic hydrocarbons (PAHs) tissue concentrations were determined, together with genotoxicity, oxidative stress and general stress biomarkers and the Integrated Biological Response (IBR) index. The bioaccumulation of individual PAHs varied depending on the exposure temperature, with relevant bioaccumulation of phenantrene and fluoranthene at 5 °C and heavier (e.g. 5-rings) PAHs at 15 °C. The values and response profiles of each particular biomarker varied with exposure time, concentration of the oil aqueous fraction and dispersant addition, as well as with exposure temperature. Indeed, PAH bioaccumulation and biomarker responsiveness exhibited specific recognizable patterns in mussels exposed at low temperatures. Thus, genotoxicity was recorded early and transient at 5 °C and delayed but unremitting at 10-15 °C. Catalase activity presented a temperature-dependent response profile similar to the genotoxicity biomarker; however, glutathione-S-transferase responsiveness was more intricate. Lysosomal membrane stability in digestive cells decreased more markedly at 5 °C than at higher temperatures and the histological appearance of the digestive gland tissue was temperature-specific, which was interpreted as the combined effects of PAH toxicity and cold stress. It can be concluded that the profile and level of the biological effects are definitely different at low temperatures naturally occurring in the Arctic/Subarctic region (e.g. 5 °C) than at higher temperatures closer to the thermal optimum of this species (10-15 °C).

Multispecies and multibiomarker assessment of fish health from Iguaçu River reservoir, Southern Brazil

This study investigated the impact of micropollutants on fish health from Segredo hydroelectric reservoir (HRS) along the Iguaçu River, Southern Brazil, contaminated by urban, industrial, and agricultural activities. This is the first comprehensive study assessment in the river after the severe drought in the 2020s in three fish species from different trophic levels Astyanax spp. (water column depth/omnivorous), Hypostomus commersoni (demersal/herbivorous), and Pimelodus maculatus (demersal/omnivorous). Animals, water, and sediment samples were collected from three distinct sites within the reservoir: Floresta (upstream), Iratim (middle), and Station (downstream). The chemical analysis revealed elevated concentrations of metals (Al, Cu, Fe) and the metalloid As in water, or Cu, Zn, and As in sediment, surpassing Brazilian regulatory limits, while the organic pollutants as DDT, PAHs, PCBs, and PBDEs were found under the Brazilian regulatory limits. The metal bioaccumulation was higher in gills with no significant differences among sites. The species Astyanax spp. and H. commersoni displayed variations in hepatosomatic index (HSI) and P. maculatus in the condition factor index (K) between sites, while adverse effects due to micropollutants bioaccumulation were observed by biochemical, genotoxic, and histopathological biomarkers. The principal component analysis and integrated biomarker response highlighted the upstream site Floresta as particularly inhospitable for biota, with distinctions based on trophic level. Consequently, this multifaceted approach, encompassing both fish biomarkers and chemical analyses, furnishes valuable insights into the potential toxic repercussions of micropollutant exposure. These findings offer crucial data for guiding management and conservation endeavors in the Iguaçu River.

Combined toxicity of polyethylene microplastics and nickel oxide nanoparticle on earthworm (Eisenia andrei): oxidative stress responses, bioavailability and joint effect

The co-occurrence of heavy metals and microplastics (MPs) is an emerging issue that has attracted considerable attention. However, the interaction of nickel oxide nanoparticle (nano-NiO) combined with MPs in soil was poorly researched. Here, experiments were conducted to study the influence of nano-NiO (200 mg/kg) and polyethylene (PE) MPs with different concentrations (0.1, 1, and 10%) and sizes (13, 50, and 500 µm) on earthworms for 28 days. Compared to control, the damage was induced by PE and nano-NiO, which was evaluated by biomarker Integrated Biomarker Response index: version 2 (IBRv2) based on six biomarkers including SOD, POD, CAT, MDA, AChE, Na+/K+-ATPase and cellulase. The majority of the chosen biomarkers showed significant but complicated responses with increasing contaminant concentrations after 28 days of exposure. Moreover, the joint effect was assessed as antagonism by the effect addition index (EAI). Overall, this work expands our understanding of the combined toxicity of PE and nano-NiO in soil ecosystems.

Environmental assessment of the central Atlantic coast of Morocco using a multibiomarker approach in Mytilus galloprovincialis

A multibiomarker approach helps assess environmental health as it provides a complete tool to understand the effects of environmental stressors on ecosystems and human health. We applied this approach in the central Atlantic Ocean of Morocco, an area subjected to the impact of many types of pollutants, threatening the durability of its resources. In this study, four biomarkers acetylcholinesterase (AChE), glutathione-s-transferase (GST), metallothioneins (MTs), and catalase (CAT) were measured in the digestive gland of the mussel Mytilus galloprovincialis collected from four sites: Imsouane (S1), Cap Ghir (S2), Imi Ouaddar (S3), and Douira (S4). These sites were chosen due to the diversity of impacts ranging from industrial to agricultural and touristic. We also assembled all the enzymatic responses (AChE, GST, CAT, and MTs), using the integrated biomarker response (IBR), to estimate the degree of impact of pollutants at the prospected sites to reveal all the complex interactions between biomarkers and to classify sites via the integrated approach. Results show a seasonal change in biomarker responses with variability between sites. We also recorded the highest levels of AChE inhibition and GST induction in S1, higher levels of catalase activity in S4, and a significant impact on metallothionein concentration in S1 and S3. This project highlights the interest in using a multibiomarker approach to ensure accurate interpretation of biomarker variation to protect the Moroccan coast and its resources.

Physiological strategies of acute thermal conditions of Rhamdia voulezi collected in the Iguaçu river watershed, Paraná, Brazil: biochemical markers of metabolic and oxidative stress

Thermal pollution creates substantial challenges that alter energy demand and produce reactive oxygen species that damage fish DNA, proteins, and lipids. Rhamdia voulezi is a species of fish native to the Iguaçu river, Paraná, Brazil, that does not have scientific records of minimum (CTmin) and maximum (CTmax) temperatures required for survival. As it is a top predator species in the food chain and lives at temperatures below 22 °C, the loss of the species can cause functional problems in controlling the ecosystem and energy flow. The study evaluated the tissue metabolism of the brain, heart, and muscle of R. voulezi (n = 72) subjected to acute thermal stress of 31 °C for 2, 6, 12, 24, and 96 h after acclimatization to 21 °C. The biochemical markers SOD, GPx, MDH, HK, and CK of the brain, PCO of the heart and CAT, glycogen, G6PDH, and ALT of muscle were significant. PCA, IBR, thermal sensitive, and condition factor suggested that R. voulezi has different physiological strategies for acclimatization to 31 °C to mobilize and sustain the metabolic needs of oxygenation and energy allocation/utilization for tissue ATP production.

Combined effects of pentachlorophenol and nano-TiO2 with different sizes on antioxidant, digestive, and immune responses of the swimming crab Portunus trituberculatus

Marine nano-titanium dioxide (nano-TiO2) and pentachlorophenol (PCP) pollution are escalating concerns in coastal areas. This study investigated the combined effects of continuous exposure to nano-TiO2 (25 nm, 100 nm) and PCP (0, 1, 10 μg/L) for 28 days on the antioxidant, digestive, and immune abilities of the swimming crab Portunus trituberculatus. Compared with the control group, the interaction between nano-TiO2 and PCP was significantly higher than exposure to a single stressor, with a pronounced decrease in amylase activity observed due to the reducing nano-TiO2 particle sizes. Resulting in increased MDA and SOD activity. The expression levels of Toll4, CSP3, and SER genes in crab hemolymph showed perturbations following exposure to nano-TiO2 and PCP. In summary, according to the results of CAT, GPX, PES and AMS enzyme activities, it was concluded that compared to the larger particle size (100 nm), the single stress of nano-TiO2 at a smaller particle size (25 nm) and co-stress with PCP have more significant impacts on P. trituberculatus. However, the potential physiological regulation mechanism of the interaction between these pollutants remains elusive and requires further study.

Assessing physiological responses and oxidative stress effects in Rhamdia voulezi exposed to high temperatures

Exposure to high temperatures induces changes in fish respiration, resulting in an increased production of reactive oxygen species. This, in turn, affects the enzymatic and non-enzymatic components of antioxidant defenses, which are essential for mitigating cellular stress. Rhamdia voulezi, an economically important fish species endemic to Brazil's Iguaçu River, served as the subject of our study. Our goal was to assess enzymatic antioxidant biomarkers (superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, glutathione reductase, glucose-6-phosphate dehydrogenase), non-protein thiol levels (reduced glutathione), and markers of oxidative damage (lipoperoxidation and carbonylation) in the liver, gills, and kidneys of R. voulezi after acute exposure to high temperatures (31°C) for 2, 6, 12, 24, and 96 h. Control groups were maintained at 21°C. Our findings revealed that the liver exhibited increased superoxide dismutase levels up to 12 h and elevated glutathione S-transferase levels at 12 and 96 h at 31°C. In the gills, superoxide dismutase levels increased up to 24 h, along with increased lipoperoxidation at 2, 6, 12, and 96 h of exposure to high temperatures. The kidneys responded to heat stress at 12 h, with an increase in superoxide dismutase and catalase activity, and lipid peroxidation was observed at 2 and 6 h at 31°C. The three tissues evaluated responded differently to heat stress, with the liver demonstrating greater physiological adjustment to high temperatures. The intricate interplay of various antioxidant defense biomarkers and oxidative damage suggests the presence of oxidative stress in R. voulezi when exposed to high temperatures.

Binary effects of fluoxetine and zinc on the biomarker responses of the non-target model organism Daphnia magna

The antidepressant effect of zinc on mammals has been documented in recent decades, and the concentration of the antidepressant fluoxetine (FLX) in aquatic environments has been rising constantly. The aim of the present study is to evaluate the combined toxicity of a serotonin reuptake inhibitor (FLX) and Zn2+ on a non-target aquatic model organism Daphnia magna. Animals were exposed to single and binary combinations of FLX (20.5 and 41 µg/L for subchronic and 41 and 82 µg/L for acute exposures) and Zn2+ (40 µg/L for subchronic and 80 µg/L for acute exposures). In vivo experiments were done for 7 days subchronic and 48 h acute exposure, while subcellular supernatants of whole Daphnia lysate (WDL) were directly treated with the same concentrations used in the acute experiments. Morphological characteristics, Ca2+-ATPase, antioxidant enzyme activities, and lipid peroxidation were examined. There was antioxidant system suppression and Ca2+-ATPase inhibition despite the diverse response patterns due to duration, concentration, and toxicant type. After acute exposure, biomarkers showed a diminishing trend compared to subchronic exposure. According to integrated biomarker response index (IBR) analysis, in vivo Zn2+ exposure was reasonably effective on the health of D. magna, whereas exposure of WDL to Zn2+ had a lesser impact. FLX toxicity increased in a concentration-dependent manner, reversed by the combined exposure. We concluded that potential pro-oxidative and adverse Ca2+-ATPase effects of FLX and Zn2+ in D. magna may also have harmful impact on ecosystem levels. Pharmaceutical exposure (FLX) should be considered along with their potential to interact with other toxicants in aquatic biota.

Assessing combined effects of long-term exposure to copper and marine heatwaves on the reef-forming serpulid Ficopomatus enigmaticus through a biomarker approach

Sessile benthic organisms can be affected by global changes and local pressures, such as metal pollution, that can lead to damages at different levels of biological organization. Effects of exposure to marine heatwaves (MHWs) alone and in combination with environmentally relevant concentration of copper (Cu) were evaluated in the reef-forming tubeworm Ficopomatus enigmaticus using a multi-biomarker approach. Biomarkers of cell membrane damage, enzymatic antioxidant defences, metabolic activity, neurotoxicity, and DNA integrity were analyzed. The exposure to Cu alone did not produce any significant effect. Exposure to MHWs alone produced effects only on metabolic activity (increase of glutathione S-transferase) and energy reserves (decrease in protein content). MHWs in combination with copper was the condition that most influenced the status of cell homeostasis of exposed F. enigmaticus. The combination of MHWs plus Cu exposure induced increase of protein carbonylation and glutathione S-transferase activity, decrease in protein/carbohydrate content and carboxylesterase activity. This study on a reef-forming organism highlighted the additive effect of a climate change-related stressor to metals pollution of marine and brackish waters.

Iron and aluminum ore mining pollution induce oxidative and tissue damage on fruit-eating bats from the Atlantic Forest

Mining, a vital industry for economic growth, poses significant environmental pollution challenges. Failures in tailings dam containment have caused environmental contamination and raised concerns about preserving the globally significant biodiversity in the Atlantic Forest, which is under severe threat. Fruit-eating bats are key for forest regeneration as essential seed dispersers and pollinators. This study focuses on two keystone species, Artibeus lituratus and Sturnira lilium, exploring the effects of iron ore mining area (FEOA) and aluminum ore mining area (ALOA) on these bats, respectively, and comparing to individuals from a preserved Atlantic Forest fragment (FFA). Bats from FEOA showed higher Aluminum (Al), Calcium (Ca), Iron (Fe) and Barium (Ba) liver accumulation, as well as Ca and Fe muscle accumulation. These animals also showed higher liver and kidney oxidative damage associated with liver fibrosis and kidney inflammation. Brain and muscle also showed oxidative stress. Bats from ALOA showed higher Ca and Ba liver accumulation and Ca, Zinc (Zn), and Ba muscle accumulation, along with higher brain oxidative stress, liver fibrosis, and kidney inflammation. Our findings indicate that iron and aluminum ore mining activities cause adverse effects on bat tissues, posing a potential threat to biodiversity maintenance in the Atlantic Forest.

Size-dependent effects of plastic particles on antioxidant and immune responses of the thick-shelled mussel Mytilus coruscus

Micro-/nano-plastic particles (MNPs) are present in the ocean with potential detrimental impacts on marine ecosystems. Bivalves are often used as marine bioindicators and are ideal to evaluate the threat posed by various-sized MNPs. We exposed the mussel Mytilus coruscus to MNPs with different particle sizes (70 and 500 nm, 5, 10 and 100 μm) for 3, 72 h and 30 days. The antioxidant responses in digestive gland and the hemolymph were then evaluated. The time of exposure played a strong modulating role in the biological response. A 3-hour exposure had no significant impact on the digestive gland. After 72 h, an increase in oxidative stress was observed in the digestive gland, including increased hydrogen peroxide (H2O2) level, catalase (CAT), glutathione peroxidase (GPx) activities and malondialdehyde (MDA) production. After a 30-day exposure, the oxidative stress decreased while lipid peroxidation increased. A 30-day exposure increased hemocyte mortality (HM) and reactive oxygen species (ROS) levels in the hemolymph, while phagocytosis (PA), lysosome content (LC), mitochondrial number (MN) and mitochondrial membrane potential (MMP) significantly decreased. Longer-term exposure to MNPs caused oxidative stress in the digestive gland as well as impaired viability and immunity of hemocytes. Particle size also influenced the response with smaller particles having more severe effects. A depuration for 7 days was enough to reverse the negative effects observed on the digestive gland and hemolymph. This study provides new insights on the effects of small-sized MNPs, especially nanoplastic particles (NPs), on aquatic organisms, and provides a solid theoretical knowledge background for future studies on toxic effects of MNPs.

Concentration-dependent effects of lithium on Daphnia magna: Life-history profiles and integrated biomarker response implementation

The growing use of lithium (Li) in industrial and energy applications and increasing demand worldwide has inevitably resulted in its wide dispersal, representing a significant threat to aquatic systems. Unfortunately, as a ubiquitous emerging contaminant, the comprehensive toxicological information regarding Li at multifarious levels is limited. To diminish this gap, this work was focused to explore Li-induced cascading effects on Daphnia magna as a key species in freshwater ecosystems. Specifically, the organisms were chronically exposed to gradient Li concentrations with emphasis on characterizing life-history traits from individual to population scale, primarily as observed by a markedly concentration-dependent decrease along exposure gradients. In parallel, a robust set of biomarkers relating to energy reserves, antioxidant and biotransformation enzymes, cellular damage, ionoregulation and neurotoxicity were assayed for further understanding potential underlying mechanisms. As a result, biomarker alterations were characterized by significant decreases in energy storage and enzymatic profiles of antioxidant and biotransformation systems, not only triggering an imbalance between reactive oxygen species (ROS) generation and elimination under Li exposure, but compromising the fecundity fitness of phenotypical costs. In contrast, malondialdehyde (MDA) levels were remarkably enhanced as a consequence of inefficient antioxidant and biotransformation capacity leading to lipid peroxidation (LPO). Additionally, Li exerted a dose-dependent biphasic effect on the activities of superoxide dismutase (SOD), Na+,K+-ATPase and acetylcholinesterase (AChE) by interfering with inherent balance. In terms of responsive patterns and dose-effect trends, the integrated biomarker response indices (IBRv2) and star plots were consistent with the differences in biomarker profiles, not only presenting comprehensively biological effects in a visualized form, but signaling the importance of progressive induced changes in an integrative way. Overall, these findings highlighted the need for elucidating Li-produced impacts from a comprehensive perspective, providing valuable insights into better understanding the toxicity of Li in relation to aquatic ecosystem functioning and ecological relevance.

Low-frequency noise aggravates the toxicity of cadmium in sea slug Onchdium reevesii

Industrial development not only triggers heavy metal pollution but also introduces a less easily discernible disturbance: low-frequency noise pollution. Low-frequency noise can disrupt wildlife behavior, potentially exerting complex effects through interacting with heavy metals. Nevertheless, the cumulative impacts of low-frequency noise and cadmium (Cd) pollution on marine organisms remain largely unexplored. This study aimed to evaluate the immune defense response of sea slugs (Onchdium reevesii) exposed to Cd (1.32 mg/L) and low-frequency noise (500 Hz, 1000 Hz). Our results show that Cd exposure results in Cd2+ accumulation in the sea slug's hepatopancreas, leading to a decrease in total antioxidant capacity (TAC) and a significant increase in enzyme activities, including glutathione (GSH), lipid peroxidation (LPO), and aspartate transferase (AST). Additionally, there is a substantial upregulation in the expression of genes related to tumor protein p53 (p53), Cytochrome C (CytC), Caspase 3, and Caspase 9, as well as metallothionein (MT) and heat shock protein 70 (Hsp70) genes. Concurrently, an excessive production of reactive oxygen species (ROS) occurs in the hemocytes, resulting in apoptosis and subsequent diminished cell viability, with these effects positively correlating with the exposure duration. Furthermore, when sea slugs were exposed to both Cd and low-frequency noise, there was a decrease in the hepatopancreas's antioxidant capacity and an enhancement in hemocytes immune responses, which positively correlated with low-frequency noise frequency. The comprehensive assessment of biomarker responses highlights that low-frequency noise has the potential to amplify the deleterious effects of Cd on sea slug physiology, with this negative impact positively linked to noise frequency. Consequently, our study underscores that the combined influence of low-frequency noise and Cd pollution magnifies the effects on sea slug health. This could potentially disrupt the population stability of this species within its natural habitat, providing fresh insights into the evaluation of cumulative environmental pollution risks.

Pollutant bioaccumulation in sentinel fish chronically exposed in Iguaçu river reservoirs (Southern Brazil) and human health risk of fish consumption

Bioaccumulation studies in fish mark the initial phase of assessing the risk of chemical exposure to biota and human populations. The Iguaçu River boasting a diverse endemic ichthyofauna, is grappling with the repercussions of human activities. This study delved into the bioaccumulation of micropollutants, the early-warning effects on Rhamdia quelen and Oreochomis niloticus in the Segredo Reservoir (HRS) and the potential risk of human exposure. Two groups of caged fish in three sites of the reservoir were exposed during the autumn-winter and spring-summer, while a third group (O. niloticus) underwent a twelve-month exposure, and inorganic and organic chemicals analysis in water, sediment, and biota. Additionally, metallothionein expression and genotoxicity were employed as biomarkers. PAHs, PCBs, Al, Cu, Fe, and As in water and DDTs, Cu, Zn, and As in sediment surpassed the thresholds set by Brazilian regulations, where DDT exhibited bioaccumulation in muscle, alongside metals in liver, kidney, gills, and muscle tissues. R. quelen showed metallothionein expression whereas DNA damage and NMA frequencies were elevated in target organs and in brain and erythrocytes of O. niloticus during summer. In this species the DNA damage in liver was remarkable after twelve months. Target Hazard Quotients and Cancer Risk values shedding light on the vulnerability of both children and adults. The reservoir's conditions led to heightened sensitivity to micropollutants for R. quelen species. The data presented herein provides decision-makers with pertinent insights to facilitate effective management and conservation initiatives within the Iguaçu Basin.

The use of integrative tools and multiple models for aquatic environmental quality assessment: a case study of the Mirim Lagoon, Southern Brazil

This study performed toxicity assays with microalgae, microcrustaceans, and fish as well as evaluated biochemical and behavioral biomarkers in fish and microcrustaceans to assess the quality of the surface water of Mirim Lagoon, which belongs to one of the largest hydrographic basins in the world, located in southern Brazil. Three distinct sampling periods were chosen (January, March, and June 2022) based on the rice plantation dynamics which is the main activity surrounding the lagoon. In January, the plantation is irrigated; in March, the water is drained into the Mirim Lagoon, and July is the off-season. Concerning toxicity tests, there was significant inhibition in microalgae growth when exposed to water collected in March, but no mortality was observed for Ceriodaphia dubia, Daphnia magna, and Danio rerio. Regarding biomarkers, behavioral variables contributed more to the higher values of the Integrated Biomarker Response (IBR) index for both D. magna and D. rerio, in March. The Redundancy Analysis (RDA) indicated a correlation between the biomarkers for both organisms and abiotic parameters, mainly nutrients (total phosphorus and total nitrogen), thermotolerant coliforms, total solids, and turbidity. Spatially, there was no difference during monitoring, but the most significant ecotoxicological effects were observed in March. Multivariate analysis and the IBR index proved to be useful tools for monitoring of water bodies such as Mirim Lagoon.

The combined effects of phenanthrene and micro-/nanoplastics mixtures on the cellular stress responses of the thick-shell mussel Mytilus coruscus

Pollution with complex mixtures of contaminants including micro- and nano-plastics (MNPs) and organic pollutants like polycyclic aromatic hydrocarbons (PAH) poses a major threat to coastal marine ecosystems. Toxic mechanisms of contaminant mixtures are not well understood in marine organisms. We studied the effects of single and combined exposures to polycyclic aromatic hydrocarbon phenanthrene (Phe) and MNPs mixture with sizes of 70 nm, 5 μm and 100 μm on the immune health and oxidative stress parameters in the thick-shell mussel Mytilus coruscus. Immune cells (hemocytes) were more sensitive to the pollutant-induced oxidative stress than the gills. In hemocytes of co-exposed mussels, elevated mortality, lower lysosomal content, high production of reactive oxygen species (ROS) and decrease mitochondrial were found. Disparate responses of antioxidant enzymes in the hemolymph (e.g. increased superoxide dismutase (SOD) activity without a corresponding increase in catalase (CAT) in Phe exposures and an increase in CAT without a change in SOD in MNPs exposures) suggests misbalance of the antioxidant defense in the pollutant-exposed mussels. Gill lacked pronounced oxidative stress response showing a decline in ROS and antioxidant levels. Tissue-specific single and combined effects of Phe and MNPs suggest variation in bioavailability and/or different sensitivity to these pollutants in the studied tissues. Notably, the combined effects of MNPs and Phe were additive or antagonistic, showing that MNPs do not enhance and occasionally mitigate the toxic effects of Phe on the hemocytes and the gills of the mussels. Overall, our study sheds light on the impact of long-term exposure to MNPs and Phe mixtures on mussels, showing high sensitivity of the immune system and modulation of the Phe toxicity by MNPs co-exposure. These findings that may have implications for understanding the impacts of combined PAH and MNPs pollution on the health of mussel populations from polluted coastal habitats.

Integrated biomarker responses: a further improvement of IBR and IBRv2 indexes to preserve data variability in statistical analyses

In biomonitoring and laboratory studies, it is typical to measure a battery of molecular, biochemical, and cytogenetic biomarkers to evaluate the effects of xenobiotics in biota. However, summarizing the results of several biomarkers to inform laypersons and environmental agencies is still a challenge for researchers and environmental specialists. To address this issue, researchers have developed indexes such as the Integrated Biomarker Responses (IBR) and Integrated Biomarker Response version 2 (IBRv2) to summarize all biomarkers responses into a single value. Unfortunately, these indexes do not preserve the original biological variability, which hampers subsequent statistical analyses. In this study, we created new versions of IBR and IBRv2, which preserve individual data variability and can be used in typical statistical analyses. The new Integrated Biomarker Responses individual (IBRi), Integrated Biomarker Responses version 2 individual (IBRv2i) and Weighted Integrated Biomarker Responses version 2 individual (Weighted IBRv2i) indexes correlated with the original IBR and IBRv2 indexes and were able to detect differences among experimental groups in a simulated and case studies. Using the IBRi, IBRv2i, or Weighted IBRv2i indexes is advantageous because they maintain the data variability of the experimental groups and can be analyzed using hypothesis testing statistics like any other parameter. Additionally, this approach can help translate technical scientific terminology into a more accessible language suitable for environmental governmental agencies and decision-makers.

Management strategy influences coral oxidative stress responses in a marine protected area in the Southwestern Atlantic

Coral reefs are experiencing accelerated degradation due to global and local stressors. The understanding of how corals cope with these disturbances is urgent. We focused on elucidating antioxidant capacity responses of the Mussismilia harttii and Siderastrea sp. corals, in reefs with use management in a marine protected area. We tested whether the activity of antioxidant enzymes in healthy colonies is higher at multiple-use reefs than at no-take reef, and whether the activity of antioxidant enzymes is higher for bleached than for healthy Siderastrea sp. colonies. Lipid peroxidation and enzymatic activity found in bleached colonies evidence chronic stress and cellular damage not related to thermal anomalies. Chronic stress in healthy colonies was also found but responses differed among species, being higher at multiple use reefs, mainly for Siderastrea sp. We highlight the role of the local conservation actions in the integrity of coral physiology and reef resilience under global climate changes.

Combined toxic effects of nanoplastics and norfloxacin on antioxidant and immune genes in mussels

Nanoplastics (NPs) and antibiotics (ABs) are two of the emerging marine contaminants that have drawn the most attention in recent years. Given the necessity of figuring out the effects of plastic and antibiotic contamination on marine organism life and population in the natural environment, it is essential to apply rapid and effective biological indicators to evaluate their comprehensive toxic effects. In this study, using mussel (Mytilus coruscus) as a model, we investigated the combined toxic effects of NP (80 nm polystyrene beads) and AB (Norfloxacin, NOR) at environmental-relevant concentrations on antioxidant and immune genes. In terms of the antioxidant genes, NPs significantly increased the relative expression of Cytochrome P450 3A-1 (CYP3A-1) under various concentrations of NOR conditions, but they only significantly increased the relative expression of CYP3A-2 in the high concentration (500 μg L-1 NOR) co-exposure group. In the NP-exposure group which exposed to no or low concentrations of NOR, nuclear factor erythroid 2-related factor 2 (Nrf2) was upregulated. In terms of the immune genes, interleukin-1 receptor-associated kinase (IRAK) -1 showed a significant increase in the low-concentration NOR group while a significant inhibition in the high-concentration NOR group. Due to the presence of NPs, exposure to NOR resulted in a significant increase in both IRAK-4 and heat shock protein (HSP) 70. Our findings indicate that polystyrene NPs can exacerbate the effects of NOR on the anti-oxidant and immune defense performance of mussels. This study delves into the toxic effects of NPs and ABs from a molecular perspective. Given the expected increase in environmental pollution due to NPs and ABs, future research is needed to investigate the potential synergistic effect of NPs and ABs on other organisms.

Antioxidant enzyme activity and pathophysiological consequences in the sludge worm Tubifex tubifex under acute and sub-lethal exposures to the fungicide Tilt ®

This study aimed to evaluate the effects of propiconazole on the tubificid segmented worm, Tubifex tubifex. The animals were exposed to various concentrations of propiconazole for 96 h to assess the acute effect of this fungicide and for subacute level animals were exposed for 14 days with 10% and 20% of the 96 h LC50 value (0.211 and 0.422 mg/l, respectively). The 96 h LC50 value was determined to be 2.110 mg/l, and sublethal propiconazole concentrations caused significant changes in the oxidative stress enzymes. When compared to control organisms, superoxide dismutase (SOD) and catalase (CAT) activity first decreases and then significantly increases on days 7 and 14. However, GST activity decreases and MDA concentration rises in a concentration- and time-dependent manner throughout the exposure period. In addition, the impacts of propiconazole on Tubifex tubifex were characterized and depicted using a correlation matrix and an integrated biomarker response (IBR) assessment. These findings suggest that exposure to this fungicide distorts the survivability and behavioral response in Tubifex tubifex at the acute level. In addition, it modulates changes in oxidative stress enzymes at the sublethal level. Furthermore, the species sensitivity distribution curve indicates that this tubificid worm has a high risk of survival in the presence of the fungicide propiconazole in aquatic ecosystems.

Impacts of Nile Tilapia (Oreochromis niloticus) exposed to microplastics in bioflocs system

Microplastics (MPs) are abundant in aquaculture water, including in bioflocs aquaculture systems. Compared with other aquaculture systems, biofloc technology systems have the richest microbes and are beneficial to cultivated organisms. Therefore, this study provides a comprehensive assessment of the potential effects of MPs on aquaculture organisms in bioflocs systems. Here, Nile Tilapia (Oreochromis niloticus) were exposed to MPs (polystyrene; 32-40 μm diameter) with 0, 80 items/L (30 μg/L), and 800 items/L (300 μg/L) for 28 days in a bioflocs aquaculture system. The results showed that the MPs generally had no apparent effect on water quality, tilapia growth, or digestive enzyme activity. However, MPs accumulated the most in the liver (5.65 ± 0.74 μg/mg) and significantly increased the hepato-somatic index of tilapia and reduced the crude protein and lipid of tilapia muscle (p < 0.05). The levels of the antioxidant enzymes catalase and glutathione S-transferase increased significantly in response to MPs (p < 0.05). In contrast, MPs did not affect the content of glutathione, glutathione peroxidase, oxidized glutathione, and malondialdehyde, or the enzyme activity of Na+/K+-ATPase. Moreover, using an improved integrated biomarker response index, growth performance was found to be less responsive to MPs than to oxidative stress and digestive activity. Exposure to MPs did not significantly influence the microbial communities of the bioflocs and tilapia guts (p < 0.05). These results suggest that MPs barely affected tilapia in the bioflocs system. This study contributes to the evaluation of the ecological risk of MPs in aquaculture systems and a better understanding of the integrated response of cultivated vertebrates to MPs in biofloc technology systems.

Integrated Biomarker responses in the mollusk, Patella vulgata: Assessing Aquatic pollution in Agadir Bay, South Morocco

In Agadir Bay, a study evaluated pollution biomarkers in the mollusk species Patella vulgata. Samples were collected seasonally from September 2021 to September 2022 at two distinct coastal sites within Agadir Bay: Cap Ghir and Anza Beach. Notable variations were observed in biomarkers like malondialdehyde, with a peak at 10.62 nmol/mg P in spring 2022 at Anza Beach. Catalase activity spiked in spring at 69.56 µmol/min/mg P for Cap Ghir and 72.73 µmol/min/mg P for Anza Beach. Acetylcholinesterase showed a decrease at 9.84 nmol/min/mg P in autumn at Anza Beach. Meanwhile, glutathione-S-transferase recorded an increase to 317.96 nmol/min/mg P at Cap Ghir in spring 2022. Using the Integrated Biomarker Response (IBR), these results were visualized, highlighting more stress in mollusks from Anza Beach compared to Cap Ghir. This research provides critical insights into the environmental effects on P. vulgata and potential conservation strategies.

Multi-biomarker approach for the (eco)toxicity of UV-filter environmental pollution on the Mediterranean mussel Mytilus galloprovincialis in a multiple stressor context. The case of 4-MBC under salinity shifts

Marine-coastal ecosystems are rapidly transforming because of climate change (CC). At the same time, the impacts of emerging organic contaminants (i.e., organic UV-filters) on these ecosystems are intensifying. In the Mediterranean, the consequences of these disturbances are occurring at a fast pace making this area a potential sentinel site to be investigated. While singular effects of organic UV-filters or CC-related factors on marine biota have been relatively described, their combined impact is still largely unknown. Thus, the objective of this study was to assess the long-term responses of the Mediterranean mussel Mytilus galloprovincialis towards anticipated salinity changes (decreases-S20 or increases-S40) when exposed to environmentally relevant concentrations of the UV-filter 4-methylbenzylidene camphor (4-MBC). An integrated multi-biomarker approach was applied, featuring general and oxidative stress, antioxidant and biotransformation enzyme capacity, energy metabolism, genotoxicity, and neurotoxicity biomarkers. Results showed that both projected salinities, considered separately, exerted non-negligible impacts on mussels' health status, with greater biological impairments found at S 40. Combining both stressors resulted in an evident increase in mussels' susceptibility to the UV-filter, which exacerbated the toxicity of 4-MBC. The dominant influence of salinity in the climate change-contaminant interaction played a crucial role in this outcome. The most severe scenario occurred when S 20 was combined with 4-MBC. In this situation, mussels exhibited a decrease in filtration rate, metabolic capacity and deployment of energy reserves increased, with an upregulation of biotransformation and inhibition of antioxidant enzyme activities. This exposure also led to the observation of cellular and DNA damage, as well as an increase in AChE activity. Furthermore, salinity-dependent bioaccumulation patterns were evaluated revealing that the lowest values in contaminated mussels are found at S 20. Overall, the present findings provide evidence that projected CC/pollutant scenarios may represent high risks for mussels' populations, with global relevant implications for the ecosystem level.

Toxicity assessment of poultry-waste biosynthesized nanosilver in Anabas testudineus (Bloch, 1792) for responsible and sustainable aquaculture development-A multi-biomarker approach

The current study investigates the potential utilization of poultry intestines for the synthesis of stable silver nanoparticles (AgNPs) and their impact on fish physiology. The AgNPs were synthesized and characterized using various analytical techniques. The toxicity of AgNPs on Anabas testudineus was evaluated, determining a 96-h LC50 value of 25.46 mg l-1. Subsequently, fish were exposed to concentrations corresponding to 1/10th, 1/25th, 1/50th, and 1/100th of the estimated LC50 for a duration of 60 days in a sub-acute study. A comprehensive range of biomarkers, including haematological, serum, oxidative stress, and metabolizing markers, were analyzed to assess the physiological responses of the fish. Additionally, histopathological examinations were conducted, and the accumulation of silver in biomarker organs was measured. The results indicate that silver tends to bioaccumulate in all biomarker organs in a dose- and time-dependent manner, except for the muscle tissue, where accumulation initially increased and subsequently decreased, demonstrating the fish's inherent ability for natural attenuation. Analysis of physiological data and integrated biomarker responses reveal that concentrations of 1/10th, 1/25th, and 1/50th of the LC50 can induce stress in the fish, while exposure to 1/100th of the LC50 shows minimal to no stress response. Overall, this study provides valuable insights into the toxicity and physiological responses of fish exposed to poultry waste biosynthesized AgNPs, offering potential applications in aquaculture while harnessing their unique features.

Earlier biomarkers in fish evidencing stress responses to metal and organic pollution along the Doce River Basin

The Doce River Basin (DRB) represents a well-described watershed in terms of contamination by metals, especially after a major environmental disaster of a mining tailing dam failure. Despite the massive mortality of the ichthyofauna, very few studies addressed the risks to the health of wild fish exposed to complex mixtures of pollutants from multiple sources. The present study proposed to investigate earlier responses of fish for assessing the impacts of multiple sources of pollution, considering: different niches of fish and target organs; and the influence of seasonality, associated with their probable sources of pollution. To achieve that, fish were collected along the DRB, and biomarkers responses were assessed in target organs and correlated with the levels of inorganic and organic contaminants. As one of the most prominent responses, fishes from the Upper DRB showed the highest expression of the metallothionein and oxidative stress parameters which were related to the higher levels of metals in this region due to the proximity of mining activities. On the other hand, higher levels of DNA damage and increased AChE activity from fish sampled in the Mid and Lower DRB were more associated with organic contaminants, from other sources of pollution than mining residues. The integrated biomarker responses also revealed seasonal variations, with higher values in fishes from the dry season, and pelagic fish showing greater variation within the seasons. The multivariate analysis integrating suitable biomarkers with chemical data represented an adequate strategy for assessing the ecological risks in the DRB, allowing the identification of distinct spatio-temporal impacts from multiple sources of contaminants. The continued exposure of the ichthyofauna representing future risks reinforces the need for ecological restoration and the protection of the fauna from the Doce River.

Ecotoxicity of emerging contaminants in the reproductive organ of marine mussels Mytilus galloprovincialis

Contaminants of emerging concern (CECs) present a new threat to the marine environment, and it is vital to understand the interactions and possible toxicity of CEC mixtures once they reach the ocean. CECs-such as metal nanoparticles, nanoplastics, and pharmaceuticals-are groups of contaminants some of which have been individually evaluated, though their interactions as mixtures are still not fully understood. To ensure a healthy and prosperous future generation, successful reproduction is key: however, if hindered, population dynamics may be at danger leading to a negative impact on biodiversity. This study aimed to understand the effects of silver (20 nm nAg, 10 μg/L), polystyrene nanoparticles (50 nm nPS, 10 μg/L), and 5-fluorouracil (5FU, 10 ng/L) individually and as a mixture (10 μg/L of nPS + 10 μg/L of nAg +10 ng/L of 5FU) in the gonads of Mytilus galloprovincialis. A multibiomarker approach, namely the antioxidant defence system (ADS; superoxide dismutase, catalase, glutathione peroxidases, glutathione - S - transferases activities), and oxidative damage (OD; lipid peroxidation) were analysed in the gonads of mussels. All exposure treatments after 3 days led to an increase of enzymatic activity, followed by an inhibition after 14 and 21 days. Thus, ADS was overwhelmed due to the generation of ROS, resulting in OD, except for nPS exposed mussels. The OD in Mix exposed mussels increased exponentially by 57-fold. When CEC mixtures interact, they are potentially more hazardous than their individual components, posing a major threat to marine species. To understand synergistic and antagonistic interactions, a model was applied, and antagonistic interactions were observed in evaluated biomarkers at all time-points, apart from a synergistic interaction at day 3 relative to LPO. Results indicate that the effects observed in Mix-exposed mussel gonads are mainly due to the interaction of nAg and 5FU but not nPS.

Ecogenotoxicity assessment with land snails: A mini-review

In the context of the increasing environmental and sanitary crisis, it is accepted that soil pollution can cause health alterations and disturb natural population dynamics. Consequently, the assessment of the genotoxic potential of compounds found in contaminated soils is important. Indeed, the alteration of genomic integrity may increase the risk of cancer development and may impair reproduction and long-term population dynamics. Among the methodologies to assess terrestrial genotoxic potential, there has been growing interest during the last decade in monitoring alterations of the genome in bioindicators of soil quality. As some land snail species are recognized bioindicators of soil quality, especially to assess the environmental and toxicological bioavailability of compounds, this review focuses on current knowledge regarding the genotoxicology of land snails. Classical biomarkers to assess genotoxic effects have been used (e.g., DNA breakage, micronuclei, random amplification polymorphic DNA) at various stages of the life cycle, including embryos. The studies were performed in vitro, in vivo, in situ and ex situ and covered a diverse set of contaminants (nanoparticles, metal(loid)s, pesticides, polycyclic aromatic hydrocarbons) and snail species (Cantareus aspersus, Eobania vermiculata, Theba pisana, Helix lucorum). Based on recent studies reviewed here, the use of land snails to map soil genotoxic potential is promising due to their ability to reveal pollution and subsequent environmental risks. Moreover, the position of snails in the trophic chain and the existing bridges between contaminant bioavailability to snails and bioaccessibility to humans reinforce the value of land snail-based ecotoxicological assessment.

Single and combined effects of caffeine and salicylic acid on mussel Mytilus galloprovincialis: Changes at histomorphological, molecular and biochemical levels

Caffeine (CAF) and salicylic acid (SA) are frequently detected in waterbody, though information on their biological impact is poor. This work assesses the effects of CAF (5ng/L to 10µg/L) and SA (0.05µg/L to 100µg/L) alone and combined as CAF+SA (5ng/L+0.05µg/L to 10µg/L+100µg/L) on mussel Mytilus galloprovincialis under 12-days exposure by histomorphology of digestive gland and oxidative stress defense at molecular and biochemical levels. Besides evaluating tissue accumulation, absence of histomorphological damage and haemocyte infiltration highlighted activation of defensive mechanisms. Up-regulation of Cu/Zn-sod, Mn-sod, cat and gst combined with increased catalase and glutathione S-transferase activity were found in CAF-exposed mussels, while SA reduced ROS production and mitochondrial activity. CAF+SA exposure induced differential responses, and the integrated biomarker response (IBR) revealed more pronounced effects of SA than CAF. These results enlarge knowledge on pharmaceuticals impact on non-target organisms, emphasizing the need for proper environmental risk assessment.

Integrative biomarker response - Threshold (IBR-T): Refinement of IBRv2 to consider the reference and threshold values of biomarkers

The Integrated Biomarker Response (IBR) is one of the most used index in biomonitoring, especially the IBRv2 integrating a reference condition. However, some limitations remain for its routine and large-scale use. The IBRv2 is proportional to the total number of biomarkers, is dependent on the nature of biomarkers and considers all biomarkers modulations, even small and biologically non-significant. In addition, IBRv2 relies on reference values but the references are often different between each study, making it difficult to compare results between studies and/or campaigns. To overcome these limitations, the present work proposed a new index called IBR-T ("Integrated Biomarker Response - Threshold") which considers the threshold values of biomarkers by limiting the calculation of the IBR value to biomarkers with significant modulations. The IBRv2 and the IBR-T were calculated and compared on four datasets from active biomonitoring campaigns using Dreissena polymorpha, a bivalve widely used in freshwater biomonitoring studies. The comparison between indices has demonstrated that the IBR-T presents a better correlation (0.907 < r² < 0.998) with the percentage of biomarkers significantly modulated than the IBRv2 (0.002 < r² < 0.759). The IBRv2 could not be equal to 0 (0.915 < intercept <1.694) because the value was dependent on the total number of biomarkers, whereas the IBR-T reached 0 when no biomarker was significantly modulated, which appears more biologically relevant. The final ranking of sites was different between the two index and the IBR-T ranking tends to be more ecologically relevant that the IBRv2 ranking. This IBR-T have shown an undeniable interest for biomonitoring and could be used by environmental managers to simplify the interpretation of large datasets, directly interpret the contamination status of the site, use it to decision-making, and finally to easily communicate the results of biomonitoring studies to the general public.

Baseline levels of integrated biomarker response index (IBR) in Mytilus galloprovincialis (Lamarck, 1819) of BouIsmail bay for monitoring Algerian Bays (Mediterranean Sea)

The Multiple Linear Regression (MLR) technique was used to determine the relationship between the integrated biomarker response index (IBR) with the most important confounding factors (Temperature, pH, Salinity and Dissolved oxygen), in order to define: (1) the baseline assessment criteria (BAC), (2) the environmental assessment criteria (EAC) and (3) the BouIsmail Bay (BIB) -Taxonomy by using Mytilus galloprovincialis sampled from two references sites in BIB (W. Tipaza, Algeria) during one season. Therefore, our results show that, the temperature appeared as a major factor for the explanation of the model. The coefficients of determination and F values for IBR validated the efficiency of model. In addition, the use MLR, BAC and EAC values in BIB-Taxonomy can deference between unpolluted and polluted areas in BouIsmail Bay in particular and Algerian Bays in general. This approach is therefore a valuable tool that could be used for monitoring the coastal sites.

Bifenthrin disrupts cytochrome c oxidase activity and reduces mitochondrial DNA copy number through oxidative damage in pool barb (Puntius sophore)

Bifenthrin (BF), a synthetic pyrethroid is used worldwide for both agricultural and non-agricultural purposes due to its high insecticidal activity and low toxicity in mammals. However, its improper usage implies a possible risk to aquatic life. The Study was aimed to correlate the association of BF toxicity with mitochondrial DNA copy number variation in edible fish Punitus sophore. The 96-h LC 50 of BF in P. sophore was 3.4 μg/L, fish was treated with sub-lethal doses (0.34 μg/L,0.68 μg/L) of BF for 15 days. The activity and expression level of cytochrome c oxidase (Mt-COI) were measured to assess mitochondrial dysfunction caused by BF. Results showed BF reduced the level of Mt-COI mRNA in treated groups, hindered complex IV activity and increased ROS generation leading to oxidative damage. mtDNAcn was decreased in the muscle, brain and liver after BF treatment. Furthermore, BF induced neurotoxicity in brain and muscle cells through the inhibition of AchE activity. The treated groups showed elevated level of malondialdehyde (MDA) and an imbalance of antioxidant enzymes activity. Molecular docking and simulation analysis also predicted that BF binds to the active sites of the enzyme and restricts the fluctuation of active sites' residues. Hence, outcome of the study suggests reduction of mtDNAcn could be a potential biomarker to assess Bifenthrin induced toxicity in aquatic ecosystem.

Reduced Survival and Disruption of Female Reproductive Output in Two Copepod Species (Acartia clausi and A. tonsa) Exposed to the Model Endocrine Disruptor 17α-Ethinylestradiol

Estuaries are heavily impacted by pollutants from different sources such as urban sewage, industrial waste and agricultural runoff. Endocrine-disrupting chemicals (EDCs) are very concerning pollutants to estuarine wildlife, but little is known about their impact on microscopic biota such as zooplankton. The aim of this work was to investigate the effects of a model EDC, the 17α-ethinylestradiol (EE2), on two copepod species inhabiting the Basque coast (Southeastern Bay of Biscay) estuaries: Acartia clausi (autochthonous neritic species) and Acartia tonsa (non-indigenous brackish species). Female copepods were collected at population maximum time (spring for A. clausi and summer for A. tonsa) and exposed individually to 5 ng/L (low), 5 µg/L (medium) and 500 µg/L EE2 (high) doses, from environmental concentrations found in sewage effluents to toxicological concentrations. After 24 h exposure, the survival rate of experimental individuals was checked and the lethal concentration LC50 was calculated. The number of egg-producing females and the amount of egg laying and egg hatching were recorded. The integrated biomarker index (IBR) was calculated to integrate the overall effects of EE2 exposure. Both species had reduced survival rates at 500 µg/L, and the LC50 was lower in A. tonsa (158 µg/L) compared to A. clausi (398 µg/L). The number of eggs laid was significantly reduced in A. clausi at EE2 medium and high doses, while a reduction in the number of eggs in A. tonsa was observed only at the high dose. However, no significant differences were detected in the egg hatching success of exposed A. clausi and A. tonsa. IBR index showed that EE2 had the most detrimental effects on A. tonsa and A. clausi females at the 500 µg/L dose. In conclusion, after 24 h of exposure, EE2 reduced female copepod survival and disrupted reproductive output, but only at high non-environmentally relevant concentrations.

Disturbances in growth, oxidative stress, energy reserves and the expressions of related genes in Daphnia magna after exposure to ZnO under thermal stress

The toxicological effects of metal contamination are influenced by the ambient temperature. Therefore, global warming affects the toxicity of metal contamination in aquatic ecosystems. ZnO is widely used as a catalyst in many industries, and causes contamination in aquatic ecosystems. Here, we investigated the effects of ZnO concentration under elevated temperature by observing growth, oxidative stress, energy reserves and related gene expression in exposed Daphnia magna. Body length and growth rate increased in neonates exposed to ZnO for 2 days but decreased at 9 and 21 days under elevated temperature. ZnO concentration and elevated temperature induced oxidative stress in mature D. magna by reducing superoxide dismutase (SOD) activity and increasing malondialdehyde (MDA) levels. In contrast, juveniles were unaffected. Carbohydrate, protein and caloric contents were reduced throughout development in D. magna treated with ZnO and elevated temperature in all exposure periods (2, 9 and 21 days). However, lipid content also decreased in mature D. magna treated with ZnO cultured under elevated temperature, while that of juveniles showed an increase in lipid content. Therefore, energy was perhaps allocated to physiological processes for detoxification and homeostasis. Moreover, expression patterns of genes related to physiological processes changed under elevated temperature and ZnO exposure. Taken together, our results highlight that the combination of temperature and ZnO concentration induced toxicity in D. magna. This conclusion was confirmed by the Integrated Biological Response (IBR) index. This study shows that changes in biological levels of organization could be used to monitor environmental change using D. magna as a bioindicator.

Differential physiological response of marine and freshwater microalgae to polystyrene microplastics

Effects of microplastics on microalgae have not been compared from different habitat. To answer this question, three marine microalgae species (Chlorella marined, Nannochloropsis oculate, and Phaeodactylum tricornutum) and two freshwater species (Chlorella vulgaris and Tetradesmus obliquus) were selected and exposed to the environment relevant concentrations of polystyrene microplastics. The results indicated that microplastics have a significant concentration effect on the growth of microalgae. The attachment of microalgae to microplastics surface and the aggregation of microalgae with each other were observed. Under exposure of microplastics, the photosynthesis of microalgae was inhibited while the antioxidant system was activated, indicating that microplastics had a negative impact on microalgae. At the end of exposure, the oxidative stress status caused by microplastics in marine microalgae were alleviated, but the antioxidant system of freshwater microalgae was still at high levels, indicating a stress response. In addition, integrated biomarker response (IBR) indicated that the effects of microplastics on freshwater microalgae were severer than marine microalgae, which might relate to their differences in removing reactive oxygen species (ROS) effectively and membrane structure. Our study provides a reliable data for understanding the complex effects of microplastics on microalgae, and especially for comparing the differential effects of microplastics among different microalgae.

Multi-level responses of oysters Crassostrea virginica for assessing organochlorine pesticides in a Ramsar coastal lagoon in southern Mexico

Organochlorine pesticides (OCPs) have been intensively used without proper regulation and control in Latin America due to the prevalence of diseases and pests, thus posing potential risks to nontarget organisms. Initiatives for ecosystem preservation, such as to designate protected areas, may not be enough to avoid contamination by OCPs, considering that protected areas tend to be permeable to diffuse sources. Here, we investigate multi-level responses of the oyster Crassostrea virginica to OCPs in Laguna de Términos, a RAMSAR coastal lagoon in the southern Gulf of Mexico. For this aim, OCPs occurrence and concentrations in the water, sediment, and in oysters from 3 settlement banks were assessed. Enzymatic and non-enzymatic biochemical biomarkers were quantified in the oysters' mantle and digestive gland, and the human health risk due to oyster consumption was also evaluated. OCPs in water were below detection limits. Fourteen OCPs were detected in sediments (∑OCPs mean of 49 ngg^-1) and 7 in oyster tissues (∑OCPs mean of 121 ngg^-1). The occurrence of OCPs was related to the land uses along the watersheds of the rivers that drain into the lagoon. Biochemical responses were correlated with OCPs (∑HCH, ∑DDT, heptachlor and endosulfan) in sediment, and oyster tissues. OCPs in oyster tissues showed a strong association with pro-oxidant forces and oxidative stress responses (Superoxide dismutase, Catalase, Glutathione Peroxidase, and lipid peroxidation), and neurotoxicity (Acetylcholinesterase), suggesting that the current OCPs contamination exerts significant stress. Our study also shows that the consumption of oysters from the lagoon increases the potential human health risk. Considering that Laguna de Términos is a protected Ramsar site, we suggest that environmental protection measures should be increased and that a monitoring program for OCPs exposure is necessary to assess the effects on this ecosystem.

Systematic toxicological analysis of the effect of salinity on the physiological stress induced by triphenyltin in Nile tilapia

Triphenyltin (TPT), a synthetic chemical, is prevalent in complex salinity areas, including estuaries and coastal regions. However, current studies on the toxicological effects of TPT relevant to the environment at different salinities are limited. In the study, biochemical, histological, and transcriptional analyses of TPT and salinity alone, or in combination, was performed on the Nile tilapia (Oreochromis niloticus) liver. Nile tilapia exhibited weakened antioxidant defenses and liver damage. Transcriptomic analysis revealed that TPT exposure primarily affected lipid metabolism and immunity; salinity exposure alone particularly affected carbohydrate metabolism; combined exposure primarily immune- and metabolic-related signaling pathways. In addition, the single exposure to TPT or salinity induced inflammatory responses by up-regulating the expression of pro-inflammatory cytokines, whereas combined exposure suppressed inflammation by down-regulating pro-inflammatory cytokine levels. These findings are beneficial to understand the negative effects of TPT exposure in Nile tilapia in the broad salinity zones and its potential defense mechanisms.

The influence of ocean acidification and warming on responses of Scylla serrata to oil pollution: An integrated biomarker approach

Anthropogenic activities primarily combustion of fossil fuel is the prime cause behind the increased concentration of CO₂ into the atmosphere. As a consequence, marine environments are anticipated to experience shift towards lower pH and elevated temperatures. Moreover, since the industrial revolution the growing demand for petroleum-based products has been mounting up worldwide leading to severe oil pollution. Sundarbans estuarine system (SES) is experiencing ocean warming, acidification as well as oil pollution from the last couple of decades. Scylla serrata is one of the most commercially significant species for aquaculture in coastal areas of Sundarbans. Thus, the prime objective of this study is to delineate whether exposure under ocean warming and acidification exacerbates effect of oil spill on oxidative stress of an estuarine crab S. serrata. Animals were separately exposed under current and projected climate change scenario for 30 days. After this half animals of each treatment were exposed to oil spill conditions for 24 h. Oxidative stress status superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), lipid peroxidation (LPO level) and DNA damage (Comet assay) were measured. Augmented antioxidant and detoxification enzyme activity was noted except for SOD but failed to counteract LPO and DNA damage. The present results clearly highlighted the detrimental combined effect of OWA and pollution on oxidative stress status of crabs that might potentially reduce its population and affect the coastal aquaculture in impending years.

Dissecting integrated indices of multiple biomarker responses: Think before use

The multiple biomarker approach is an effective tool to study the responses of aquatic organisms to contaminants. Summarizing multiple biomarker responses for facilitated communication of research findings has been aided by some integrated indices. Here we explain how existing integrated indices were built and why they turn out to be the wheel reinvented. We discuss the role of integrated indices in ecological risk assessment and recommend some changes in summarizing multiple biomarker results. Integr Environ Assess Manag 2023;19:302-311. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Preliminary inter-port study of the quality of environments using physiological responses of invertebrates exposed to chronic trace element and organic contamination in Corsica (Mediterranean Sea)

Port areas are socio-ecosystems impacted by chronic mixture pollution. Some marine species benefit from living there and may be studied to define the ecological state of such environments. In this study, the risks of chronic chemical contamination and its consequences on three marine molluscs were evaluated in North Corsica (France) port areas. Mediterranean mussel Mytilus galloprovincialis, tubular sea cucumber Holothuria tubulosa and Mediterranean limpet Patella sp. were sampled in three port areas and a reference location. A set of biomarkers was analysed to evaluate oxidative stress, detoxification, energetic metabolism, neurotoxicity, immunity and bioaccumulation (metallic trace elements and organic pollutants). The objectives were to assess pollution-induced effects in organisms, to determine the best bioindicator species for the selected locations and to validate a "pool" sampling technique (when the analysis is done on a single pool of samples and not on individual samples). The results validate the sampling techniques as "pool" for management purposes. St-Florent was demonstrated as the most contaminated location. All the other locations present a low contamination, below the recommended threshold values (for metallic trace elements and organic pollutants). Finally, the limpet appears to be the best bioindicator for the selected locations. Mussel and sea cucumber are inappropriate due to their absence in this oligotrophic region and the lack of responses observed, respectively.

Integrated biomarker responses and metal contamination survey in the wedge clam Donax trunculus from the Atlantic coast of Morocco

In Morocco, the marine environment has always been a major occupation for socioeconomic activities (industry, tourism, urbanization, etc.). Thus, this work displays a case study of Taghazout coast in the central Atlantic part of the country, which becomes the center of several development projects, such as the touristic resort Taghazout Bay. In the aim to assess the health status of this coastal ecosystem, a multi-indicator approach based on the response of biomarkers in the wedge clam Donax trunculus was adopted during two years (2016/2017). The undertaken investigations on the response of biomarkers (AChE, GST, MDA, and CAT) in the sentinel species D. trunculus showed an activation of defense mechanisms in this bivalve, which would imply exposure to chemical stress in this ecosystem. The monitoring of seasonal bioaccumulation of cadmium (Cd), lead (Pb), and copper (Cu) by D. trunculus indicates that the bivalves collected have been exposed to these metal sources in the study area. In addition, the correlation study has reported a significant effect of environmental parameters on biomarker response. Overall, the multi-indicator approach has clearly revealed the health status of Taghazout coast registered in a coastal urbanization.

Low particle concentrations of nanoplastics impair the gut health of medaka

The environmental occurrence of nanoplastics (NPs) is now evident but their long-term impacts on organisms are unclear, limiting ecological and health risk assessment. We hypothesized that chronic exposure to low particle concentrations of NPs can result in gut-associated toxicity, and subsequently affect survival of fish. Japanese medaka Oryzias latipes were exposed to polystyrene NPs (diameter 100 nm; 0, 10, 10⁴, and 10⁶ items/L) for 3 months, and histopathology, digestive and antioxidant enzymes, immunity, intestinal permeability, gut microbiota, and mortality were assessed. NP exposures caused intestinal lesions, and increased intestinal permeability of the gut. The trypsin, lipase, and chymotrypsin activities were increased, but the amylase activity was decreased. Oxidative damage was reflected by the decreased superoxide dismutase and alkaline phosphatase and increased malondialdehyde, catalase, and lysozyme. The integrated biomarkers response index values of all NP-exposed medaka were significantly increased compared to the control group. Moreover, NP exposures resulted in a decrease of diversity and changed the intestinal microbiota composition. Our results provide new evidence that long-term NPs exposure impaired the health of fish at extremely low particle concentrations, suggesting the need for long-term toxicological studies resembling environmental particle concentrations when assessing the risk of NPs.

Do predator (Mystus gulio) and prey (Penaeus monodon) have differential response against heatwaves? Unveiling through oxidative stress biomarkers and thermal tolerance estimation

Extreme climatic events such as heatwaves are anticipated to intensify in future and impose additional thermal stress to aquatic animals. Knowledge regarding an organism's thermal tolerance or sensitivity is therefore important in determining the effects of fluctuating water temperature on physiological responses. Thus, thermal tolerance tests can serve as a first step in understanding the present and future effects of climate warming. Climatic variability will alter prey-predator attributes differentially and impact their subsequent interactions. The key objective of this study was to compare and decode the stress responses, resistance and vulnerability of two economically important species from Sundarbans estuarine system- Penaeus monodon (prey) and Mystus gulio (predator) subjected to acute thermal challenges such as sudden heatwaves. Both the species were subjected to an increasing thermal ramp of 1°C h^-1 from 22°C to 42°C. Organisms were observed continuously throughout the ramping period and changes in the locomotory behaviour were followed until their loss of equilibrium. The digestive tissue samples were dissected out from both M. gulio and P. monodon at every 2°C and also after a recovery period of 48 h. The SOD, CAT, GST, LPO were measured and integrated biomarker response (IBR) was analysed. The results from thermal tolerance maxima estimation, biomarker study, IBR responses indicated more intense stress response in fish M. gulio whereas recovery potential was greater in shrimp P. monodon. Our findings corroborate the 'trophic sensitivity hypothesis' which advocates predators to be less tolerant in aggravated environmental stress than their prey.

How do different arsenic species affect the joint toxicity of perfluorooctanoic acid and arsenic to earthworm Eisenia fetida: A multi-biomarker approach

Perfluorooctanoic acid (PFOA) and arsenic are widely distributed pollutants and can coexist in the environment. However, no study has been reported about the effects of different arsenic species on the joint toxicity of arsenic and PFOA to soil invertebrates. In this study, four arsenic species were selected, including arsenite (As(III)), arsenate (As(V)), monomethylarsonate (MMA), and dimethylarsinate (DMA). Earthworms Eisenia fetida were exposed to soils spiked with sublethal concentrations of PFOA, different arsenic species, and their binary mixtures for 56 days. The bioaccumulation and biotransformation of pollutants, as well as eight biomarkers in organisms, were assayed. The results indicated that the coexistence of PFOA and different arsenic species in soils could enhance the bioavailability of arsenic species while reducing the bioavailability of PFOA, and inhibit the arsenic biotransformation process in earthworms. Responses of most biomarkers in joint treatments of PFOA and As(III)/As(V) showed more significant variations compared with those in single treatments, indicating higher toxicity to the earthworms. The Integrated Biomarker Response (IBR) index was used to integrate the multi-biomarker responses, and the results also exhibited enhanced toxic effects in combined treatments of inorganic arsenic and PFOA. In comparison, both the biomarker variations and IBR values were lower in joint treatments of PFOA and MMA/DMA. Then the toxic interactions in the binary mixture systems were characterized by using a combined method of IBR and Effect Addition Index. The results revealed that the toxic interactions of the PFOA/arsenic mixture in earthworms depended on the different species of arsenic. The combined exposure of PFOA with inorganic arsenic led to a synergistic interaction, while that with organic arsenic resulted in an antagonistic response. Overall, this study provides new insights into the assessment of the joint toxicity of perfluoroalkyl substances and arsenic in soil ecosystems.

Biotransformation and oxidative stress responses in fish (Astyanax aeneus) inhabiting a Caribbean estuary contaminated with pesticide residues from agricultural runoff

The estuarine ecosystem of Madre de Dios Lagoon (MDL), in the Caribbean Coast of Costa Rica, is exposed to contamination with pesticide residues coming from the upstream agricultural areas. Biomarkers can provide a better indication of the fitness of biota in real mixture exposure scenarios than traditional lethal dose toxicity measurements. Here, we measured biomarkers of biotransformation, oxidative stress, and neurotoxicity on Astyanax aeneus, an abundant fish species in MDL. Glutathione S-transferase activity (GST), catalase activity (CAT), lipid peroxidation (LPO), and cholinesterase activity (ChE) were measured in fish collected during seven sampling campaigns, carried out between 2016 and 2018. Pesticide residues were analyzed in surface water samples collected every time fish were sampled. Residues of 25 pesticides, including fungicides, insecticides, and herbicides, were detected. The biomarkers measured in A. aeneus varied along the sampling moments, with biotransformation and oxidative stress signals showing a coupled response throughout the assessment. Furthermore, significant correlations were established between three biomarkers (GST, LPO, and CAT) and individual pesticides, as well as between GST and LPO with groups of pesticides with shared biocide action. Among pesticides, insecticide residues had a major influence on the responses observed in fish. This work demonstrates the chronic exposure to pesticide residues in MDL and how such exposure is related to physiological responses in fish that can affect their health and potentially, the trophic networks. This early warning information should be considered to improve the protection of estuarine ecosystems in the tropics.

Gene expression and biochemical patterns in the digestive gland of the mussel Mytilus galloprovincialis (Lamarck, 1819) exposed to 17α-ethinylestradiol

Contaminants of emerging concern (CECs) are a class of chemicals that can spread throughout the environment and may cause adverse biological and ecological effects. While there are many different classes of CECs, one of the most well documented in the aquatic environment are pharmaceutical drugs, such as natural and synthetic estrogens. In particular, the widespread presence of the synthetic estrogen 17 α-Ethinylestradiol (EE2) in water may lead to bioaccumulation in sediment and biota. EE2 is the primary component in contraceptive pills, and is a derivative of the natural hormone estradiol (E2). In this study, the mussel Mytilus galloprovincialis was exposed to EE2 in a semi-static and time-dependent experiment, for a total exposure period of 28 days. Biochemical and transcriptomics analyses were performed on mussel digestive glands after exposure for 14 (T14) and 28 (T28) days. Metabolic and DNA impairments, as well as activation of antioxidant and biotransformation enzymes activation, were detected in T28 exposed mussels. RNA-Seq analysis showed significant differential expression of 160 (T14 compared to controls), 33 (T28 compared to controls) and 79 (T14 compared to T28) genes. Signs of stress after EE2 treatment included up-regulation of gene/proteins involved with immune function, lipid transport, and metabolic and antibacterial properties. This study elucidates the underlying mechanisms of EE2 in a filter feeding organisms to elucidate the effects of this human pharmaceutical on aquatic biota.

Can high- and low-temperature thermal stress modulate the antioxidant defense response of Astyanax lacustris brain?

Change in temperature of aquatic environment have impacts on the physiology of fish, especially in the brain, which is a vital organ and prone to oxidative damage. Astyanax lacustris is a freshwater fish that play an important role in the food market and has been increasingly used in fish farms, besides environmental monitoring studies. Therefore, this study aimed to evaluate the responses of antioxidant biomarkers and products of the oxidative process in the brains A. lacustris subjected to thermal shock. The specimens were obtained from artificial farming lakes and subjected to shock induced by exposure to high (31 °C ± 0.5) and low (15 °C ± 0.5) temperature for 2, 6, 12, 24, 48, 72 and 96 h; control group were maintained at 23 °C ± 0.5. At 31 °C, glutathione-related enzymes were more responsive, suggested by the change activity of GPx and G6PDH enzymes, in addition to GSH levels. At 15 °C, enzymes of the first line of defense were more active, evidenced by the change CAT activity. No significant changes were detected in the levels of ROS, LPO and PCO. These results indicate that the brains of A. lacustris have an efficient antioxidant defense system with the ability to acclimatize to the temperatures tested.

Environmental quality and ecotoxicity of sediments from the lower Salado River basin (Santa Fe, Argentina) on amphibian larvae

The lower Salado River basin receive agricultural, industrial and domestic waste water. So, the aim was to evaluate the quality of three sampling sites that belong to the Salado River basin (S1: Cululú stream; S2: Salado River, at Esperanza City, S3: Salado River at Santo Tomé City) based on physicochemical parameters, metals and pesticides analyses and ecotoxicity on Rhinella arenarum larvae. R. arenarum larvae (Gosner Stage -GS- 25) were chronically exposed (504h) to complex matrixes of surface water and sediment samples of each site for the determination of the survival rate. Biomarkers of oxidative stress, neurotoxicity and genotoxicity were analyzed in R. arenarum larvae (GS. 25) after exposure (96h) to the complex matrix of water and sediment. The water quality index showed a marginal quality for all sites, influenced mainly by low dissolved oxygen, high total suspended solid, phosphate, nitrite, conductivity, Pb, Cr and Cu levels. Metal concentrations were higher in sediment than in water samples (˜34-35000 times). In total, thirty different pesticides were detected in all water and sediment samples, S1 presented the greatest variety (26). Glyphosate and AMPA were detected in sediments from all sites, being higher in S3. N,N-Diethyl-meta-toluamide (DEET) and atrazine were detected in all water samples. Greatest mortality was observed in larvae exposed to samples from S1 from 288h (43.3%), reaching a maximum value of 50% at 408h. Oxidative stress and genotoxicity were observed in larvae exposed to S1 and S3 matrix samples. Neurotoxicity was observed in larvae exposed to all matrix samples. The integrated biomarker response index showed that larvae exposed to S1 and S3 were the most affected. According to the physicochemical data and the ecotoxicity assessment, this important river basin is significantly degraded and may represent a risk to aquatic biota, especially for R. arenarum larvae.

Fish biomarker responses reflect landscape anthropic disturbance in savanna streams

Disturbance in the landscape surrounding streams can interfere with water quality and cause harm to aquatic organisms. In this study, we evaluate the influence of land use on the genetic and biochemical biomarkers of fish in streams of Brazilian savanna (Cerrado). We also evaluated whether biomarker responses are seasonally consistent. For this purpose, individuals of the Neotropical tetra fish Astyanax lacustris were exposed in cages for 96 h, in 13 streams draining agroecosystems with different degrees of disturbance during the dry and wet seasons. After exposure, blood, liver, and gills were collected for multibiomarker analyses (micronuclei, erythrocytic nuclear abnormalities, lipid peroxidation, antioxidant enzymes, and biotransformation enzyme). The results showed that the gradient of anthropic disturbance was positively associated with genotoxic damage (erythrocytic nuclear abnormalities) and negatively associated with antioxidant and biotransformation enzymes of the liver in both seasons. No association of the gradient of anthropic disturbance with the frequency of micronuclei and for most gill enzymes was found for both seasons. Landscape disturbance was also negatively associated with water quality in the wet season. These results indicate that changes in land use interfere with the genetic and biochemical processes of organisms. Thus, the multibiomarker approach may represent an effective strategy for assessing and monitoring terrestrial landscape disturbance.

Mechanistic insights to lactic and formic acid toxicity on benthic oligochaete worm Tubifex tubifex

Lactic and formic acid are two commonly found monocarboxylic organic acids. Lactic acid is discharged into the water bodies as acidic industrial effluent from the food, cosmetic, chemical, and pharmaceutical industries, whereas formic acid is discharged from various paper, leather tanning, and textile processing industries. The present study investigated the toxicity of both organic acids upon the benthic oligochaete worm Tubifex tubifex. The 96-h median lethal concentration (LC₅₀) values for lactic and formic acid are determined as 143.81 mg/l and 57.99 mg/l respectively. The effects of two sublethal concentrations (10% and 30% of 96 h LC₅₀) of these acids on differential expression of oxidative stress enzymes are investigated. The comparative analysis of acute toxicity demonstrates that formic acid exposure is more detrimental to T. tubifex than lactic acid. The in silico structural analysis predicts that formic acid can interact with cytochrome c oxidase of the electron transport system and thereby inhibits its functionality and induces reactive oxygen species production. Integrated biomarker response (IBR) analysis illustrates that overall oxidative stress of formic acid to T. tubifex is significantly higher than that of lactic acid, which supports the structural analysis. It is concluded from this study that toxicokinetic-toxicodynamic and species sensitivity distributions studies are helpful for ecological risk management of environmental toxicants.