Multiple-biomarker approach in the assessment of the health status of a novel sentinel mussel Brachidontes rodriguezii in a harbor area

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.

Biochemical responses, feeding and survival in the solitary bee Osmia bicornis following exposure to an insecticide and a fungicide alone and in combination

In agricultural ecosystems, bees are exposed to combinations of pesticides that may have been applied at different times. For example, bees visiting a flowering crop may be chronically exposed to low concentrations of systemic insecticides applied before bloom and then to a pulse of fungicide, considered safe for bees, applied during bloom. In this study, we simulate this scenario under laboratory conditions with females of the solitary bee, Osmia bicornis L. We studied the effects of chronic exposure to the neonicotinoid insecticide, Confidor® (imidacloprid) at a realistic concentration, and of a pulse (1 day) exposure of the fungicide Folicur® SE (tebuconazole) at field application rate. Syrup consumption, survival, and four biomarkers: acetylcholinesterase (AChE), carboxylesterase (CaE), glutathione S-transferase (GST), and alkaline phosphatase (ALP) were evaluated at two different time points. An integrated biological response (IBRv2) index was elaborated with the biomarker results. The fungicide pulse had no impact on survival but temporarily reduced syrup consumption and increased the IBRv2 index, indicating potential molecular alterations. The neonicotinoid significantly reduced syrup consumption, survival, and the neurological activity of the enzymes. The co-exposure neonicotinoid-fungicide did not increase toxicity at the tested concentrations. AChE proved to be an efficient biomarker for the detection of early effects for both the insecticide and the fungicide. Our results highlight the importance of assessing individual and sub-individual endpoints to better understand pesticide effects on bees.

Gender influences molecular and histological biomarkers in mature oysters Crassostrea gasar (Adanson, 1757) after pyrene exposure

Oysters are frequently used as sentinel organisms for monitoring effects of contaminants due to their sessile, filtering habits and bioaccumulation capacity. These animals can show elevated body burden of contaminants, such as pyrene (PYR). PYR can be toxic at a molecular level until the whole oyster, which can show reproductive and behavioral changes. Considering that biologic parameters, such as gender or reproductive stage can interfere in the toxic effects elicited by contaminants uptake, the aim of this study was to evaluate some molecular and histological responses in females and males of oyster Crassostrea gasar exposed to PYR (0.25 and 0.5 μM) for 24 h at the pre-spawning stage. PYR concentrations were analyzed in water and in tissues of female and male oysters. Gene transcripts related to biotransformation (CYP3475C, CYP2-like, CYP2AU1, CYP356A, GSTO-like, GSTM-like, SULT-like), stress (HSP70), and reproduction (Vitellogenin, Glycoprotein) were quantified in gills. In addition, histological analysis and histo-localization of CYP2AU1 mRNA transcripts in gills, mantle and digestive diverticulum were carried out. Females and males in pre-spawning stage bioconcentrated PYR in their tissues. Males were more sensitive to PYR exposure. CYP2AU1 transcripts were higher in males (p < 0.05), as well as tubular atrophy was observed only in males exposed to PYR (p < 0.05). As expected, vitellogenin transcripts were lower in males (p < 0.05). Given these results, it is suggested that levels of CYP2AU1 be a good biomarker of exposure to PYR in oyster C. gasar and that it is important to consider the gender for the interpretation of biomarker responses.

Sensitivity of histopathological and histochemical parameters in the digestive gland of the apple snail Pomacea canaliculata exposed to cypermethrin

The aim of this study was to evaluate the toxic effects of the pesticide cypermethrin (CYP) in the digestive gland of the apple snail, Pomacea canaliculata, analysing histological and histochemical alterations. Adult snails were exposed to sublethal CYP concentrations (10, 25, and 100 µg/L) under acute (1 day) and sub-chronic (14 days) conditions. Histological analyses of the morphology of the digestive gland were performed and a histopathological condition index (HI) was calculated. Also, both intracellular accumulation of lipofuscins (LF) and neutral lipids (NL) were evaluated. CYP exposure induced tissue damage to this organ, such as disorganisation of the connective tissue, fibrosis, haemocytic infiltration, atrophy, and necrosis under acute and sub-chronic conditions. These alterations, integrated into a single HI value, revealed notable CYP effects during both acute and sub-chronic exposures. Cell type replacement, measured as Vv_BAS, was only observed in the sub-chronic treatment. Under acute conditions, the pyrethroid affected NL accumulation at the highest concentration, while in sub-chronic conditions NL accumulation was only observed at the lowest concentrations. P. canaliculata also showed a dose-dependent response of LF under acute CYP exposure conditions. However, under sub-chronic conditions, this parameter was not sensitive to pesticide exposure. All these relevant structural lesions may affect the normal function of the digestive gland, even though the species presented additional mechanisms, as infiltration of hemocyte and basophilic cell hyperplasia, that help it to tolerate the exposure to pollutants. This study showed that some histological and histochemical parameters are sensitive in P. canaliculata at CYP concentrations to which the snail could be exposed in the environments it inhabits.

Marine Biotoxins in Whole and Processed Scallops from the Argentine Sea

Harmful algal blooms are an increasing worldwide threat to the seafood industry and human health as a consequence of the natural production of biotoxins that can accumulate in shellfish. In the Argentine Sea, this has been identified as an issue for the offshore fisheries of Patagonian scallops (Zygochlamys patagonica), leading to potentially harmful effects on consumers. Here we assess spatial and temporal patterns in marine biotoxin concentrations in Patagonian scallops harvested in Argentinian waters between 2012–2017, based on analyses for paralytic shellfish toxins, lipophilic toxins, and amnesic shellfish toxins. There was no evidence for concentrations of lipophilic or amnesic toxins above regulatory acceptance thresholds, with trace concentrations of pectenotoxin 2, azaspiracid 2 and okadaic acid group toxins confirmed. Conversely, paralytic shellfish toxins were quantified in some scallops. Gonyautoxins 1 and 2 dominated the unusual toxin profiles (91%) in terms of saxitoxin equivalents with maximum concentrations reaching 3985 µg STX eq/kg and with changes in profiles linked in part to seasonal changes. Total toxin concentrations were compared between samples of the adductor muscle and whole tissue, with results showing the absence of toxins in the adductor muscle confirming toxin accumulation in the digestive tracts of the scallops and the absence of a human health threat following the processing of scallop adductor meat. These findings highlight that paralytic shellfish toxins with an unusual toxin profile can occur in relatively high concentrations in whole Patagonian scallops in specific regions and during particular time periods, also showing that the processing of scallops on board factory ships to obtain frozen adductor muscle is an effective management process that minimizes the risk of poisonings from final products destined for human consumption.

Transcriptomic profiling and differential analysis revealed the neurodevelopmental toxicity mechanisms of zebrafish (Danio rerio) larvae in response to tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE) exposure

Tetrabromobisphenol A bis(2-hydroxyetyl) ether (TBBPA-DHEE) is among the main derivatives of Tetrabromobisphenol A (TBBPA). Result from previous study showed that TBBPA-DHEE can cause neurotoxicity in rat. In this study, zebrafish larvae were used for evaluation of TBBPA-DHEE-induced developmental toxicity, apoptosis, oxidative stress and the potential molecular mechanisms of action. Our result showed that TBBPA-DHEE exposure caused a significant concentration-dependent developmental toxicity endpoints like death rate, malformation rate, growth rate. TBBPA-DHEE altered locomotor and enzymes activities of larvae and caused apoptosis within the brain indicating the potential TBBPA-DHEE-induced cardiac, brain impairment in the zebrafish larvae. Our transcriptomic analysis shows that 691 genes were differentially expressed (DEGs) (539 upregulated, 152 downregulated). The KEGG and GO enrichment pathway analysis shows that the DEGs were involved in development, immunity, enzyme activity. Our study provides novel evidence on the neurodevelopmental toxicity and toxicity mechanism of TBBPA-DHEE which are vital for assessment of the environmental toxicity and risk assessment of the chemical.

Microplastics in bivalves, water and sediments from a touristic sandy beach of Argentina

This study assesses for the first time the concentrations of microplastics (MPs) in sediments, water and two human-consumed mussels with different ecological traits (Amarilladesma mactroides and Brachidontes rodriguezii) in a touristic sandy beach of Argentina. MPs were characterized through FTIR and SEM/EDX techniques. All the samples presented MPs with similar concentrations as other human-impacted coastal areas of the world, being black and blue fibers of < 0.5 and 0.5-1 mm the most abundant. SEM images exhibited cracks and fractures with clay minerals and microorganisms adhered to MPs surface. EDX spectrums showed potentially toxic elements, such as Cr, Ti, and Mo. FTIR identified polymers such as cellulose, polyamides, and polyacrylates in most of the samples analyzed. Our study demonstrates that microplastic pollution is a common threat to sandy beaches in Argentina, worsened by plastic particles carrying metal ions with potential toxic effects to the biota, including A. mactroides, an endangered species.

First application of an Integrated Biological Response index to assess the ecotoxicological status of honeybees from rural and urban areas

Understanding the effects of environmental contaminants on honeybees is essential to minimize their impacts on these important pollinating insects. The aim of this study was to assess the ecotoxicological status of honeybees in environments undergoing different anthropic pressure: a wood (reference site), an orchard, an agricultural area, and an urban site, using a multi-biomarker approach. To synthetically represent the ecotoxicological status of the honeybees, the responses of the single biomarkers were integrated by the Integrated Biological Response (IBRv2) index. Overall, the strongest alteration of the ecotoxicological status (IBRv2 = 7.52) was detected in the bees from the orchard due to the alteration of metabolic and genotoxicity biomarkers indicating the presence of pesticides, metals, and lipophilic compounds. Honeybees from the cultivated area (IBRv2 = 7.18) revealed an alteration especially in neurotoxicity, metabolic, and genotoxicity biomarkers probably related to the presence of pesticides, especially fungicides. Finally, in the urban area (IBRv2 = 6.60), the biomarker results (GST, lysozyme, and hemocytes) indicated immunosuppression in the honeybees and the effects of the presence of lipophilic compounds and metals in the environment.

Pathological conditions of the sentinel bivalve, the little mussel Brachidontes rodriguezii, from contaminated intertidal sites in the Southwestern Atlantic coast

A survey of pathological conditions affecting the natural beds of the dominant bivalve species of the intertidal rocky coasts of the Southern Atlantic Ocean, was performed. Samples of the little mussel (n = 992), Brachidontes rodriguezii, which is considered a sentinel species, were collected from seven sites that present different anthropogenic activity (low anthropogenic activity, harbor, and sewage waste) along the Argentinean coast, and processed by standard histological techniques. Our results showed for the first time in a B. rodriguezii population from Mar del Plata harbor a bacterium causing cellular lysis of the spermatogenic cells (6.5% of prevalence) and in a population from Villa Gesell, a site with low anthropogenic activity, one little mussel presented cytoplasmic vacuoles in the oocytes's cytoplasm similar to a microsporidian (0.2% of prevalence). A ciliated protozoan parasitizing the cytoplasm of the epithelial digestive tubules and larval stages of two different digenean parasites, was found infecting the little mussel from both contaminated and uncontaminated sites. Sporocysts of the family Bucephalidae invaded the gonad, causing severe gonadal damage including castration, and gymnophallid metacercariae located between the mantle and shell or embedded in the mantle tissues, occupied the gonadal space. In Punta Carballido, a site located next to a sewage outfall, the highest prevalence of infection was found, for the ciliated protozoan in the digestive tubules (5.1%) and for the digenean parasites (bucephalid sporocyst 24.4%, and gymnophallid metacercariae 50%). Moreover, we found a positive correlation between shell length and overall prevalence of parasites.

1H-NMR metabolomics profiling of zebra mussel (Dreissena polymorpha): A field-scale monitoring tool in ecotoxicological studies

Biomonitoring of aquatic environments requires new tools to characterize the effects of pollutants on living organisms. Zebra mussels (Dreissena polymorpha) from the same site in north-eastern France were caged for two months, upstream and downstream of three wastewater treatment plants (WWTPs) in the international watershed of the Meuse (Charleville-Mézières "CM" in France, Namur "Nam" and Charleroi "Cr" in Belgium). The aim was to test ¹H-NMR metabolomics for the assessment of water bodies' quality. The metabolomic approach was combined with a more "classical" one, i.e., the measurement of a range of energy biomarkers: lactate dehydrogenase (LDH), lipase, acid phosphatase (ACP) and amylase activities, condition index (CI), total reserves, electron transport system (ETS) activity and cellular energy allocation (CEA). Five of the eight energy biomarkers were significantly impacted (LDH, ACP, lipase, total reserves and ETS), without a clear pattern between sites (Up and Down) and stations (CM, Nam and Cr). The metabolomic approach revealed variations among the three stations, and also between the upstream and downstream of Nam and CM WWTPs. A total of 28 known metabolites was detected, among which four (lactate, glycine, maltose and glutamate) explained the observed metabolome variations between sites and stations, in accordance with chemical exposure levels. Metabolome changes suggest that zebra mussel exposure to field contamination could alter their osmoregulation and anaerobic metabolism capacities. This study reveals that lactate is a potential biomarker of interest, and ¹H-NMR metabolomics can be an efficient approach to assess the health status of zebra mussels in the biomonitoring of aquatic environments.

Multi-biomarker approach and IBR index to evaluate the effects of different contaminants on the ecotoxicological status of Apis mellifera

The honeybee, Apis mellifera L. (Hymenoptera: Apidae), a keystone pollinator of wild plant species and agricultural crops, is disappearing globally due to parasites and diseases, habitat loss, genetic constraints, beekeeper management issues and to the widespread use of pesticides. Besides insecticides, widely studied in this species, honeybees are also exposed to herbicides and fungicides and heavy metals whose lethal and sublethal effects need to be investigated. In this context, our study aimed to evaluate the effects of fungicides and of heavy metals on honeybees and to develop and apply a multi-biomarker approach that include an Integrated Biological Index (IBRv2) to assess the toxicological status of this species. Biomarkers of neurotoxicity (AChE and CaE), metabolic alteration (ALP, and GST) and immune system (LYS, granulocytes) were measured, following honeybees' exposure to cadmium or to a crop fungicide, using the genotoxic compound EMS as positive control. A biomarker of genotoxicity (NA assay) was developed and applied for the first time in honeybees. At the doses tested, all the contaminants showed sublethal toxicity to the bees, highlighting in particular genotoxic effects. The data collected were analyzed by an IBRv2 index, which integrated the seven biomarkers used in this study. IBRv2 index increased with increasing cadmium or fungicide concentrations. The IBRv2 represents a simple tool for a general description of honeybees ecotoxicological health status. Results highlight the need for more in-depth investigations on the effects of fungicides on non-target organisms, such as honeybees, using sensitive methods for the determination of sublethal effects. This study contributes to the development of a multi-biomarker approach to be used for a more accurate ecotoxicological environmental monitoring of these animals.

Mollusk shell alterations resulting from coastal contamination and other environmental factors

Effects of contamination on aquatic organisms have been investigated and employed as biomarkers in environmental quality assessment for years. A commonly referenced aquatic organism, mollusks represent a group of major interest in toxicological studies. Both gastropods and bivalves have external mineral shells that protects their soft tissue from predation and desiccation. These structures are composed of an organic matrix and an inorganic matrix, both of which are affected by environmental changes, including exposure to hazardous chemicals. This literature review evaluates studies that propose mollusk shell alterations as biomarkers of aquatic system quality. The studies included herein show that changes to natural variables such as salinity, temperature, food availability, hydrodynamics, desiccation, predatory pressure, and substrate type may influence the form, structure, and composition of mollusk shells. However, in the spatial and temporal studies performed in coastal waters around the world, shells of organisms sampled from multi-impacted areas were found to differ in the form and composition of both organic and inorganic matrices relative to shells from less contaminated areas. Though these findings are useful, the toxicological studies were often performed in the field and were not able to attribute shell alterations to a specific molecule. It is known that the organic matrix of shells regulates the biomineralization process; proteomic analyses of shells may therefore elucidate how different contaminants affect shell biomineralization. Further research using approaches that allow a clearer distinction between shell alterations caused by natural variations and those caused by anthropogenic influence, as well as studies to identify which molecule is responsible for such alterations or to determine the ecological implications of shell alterations, are needed before any responses can be applied universally.

Uso de biomarcadores en la evaluación ambiental de ecosistemas marinos en América

The use of biomarkers in the assessment of the marine environmental status offers an integrated approach to the effects caused by diverse pollutants. This article compiles and analyzes the original research on the study of possible biomarkers in wild coastal-marine organisms from America. One of the outcomes of this review research is the need for a continuous evaluation of organisms in conjunction with the assessment of environmental vari-ables and the levels of pollutants that may be found in any ecosystem. It is well stated that the use of biomarkers is a practical tool for the environmental management; however, some limitations apply and there are several questions in regards to specificity, sensibility, usability, replicability, and interpretation to be solved, yet. Along the American continent, multiple biomarkers have been used to evaluate specific pollutants or highly impacted zones at marine-coastal environments. The most commonly used organisms are fishes and bivalves and they have been also extensively used in marine turtles. In regards of the type of biomarkers, plenty of authors integrate biomarkers from different groups, sorted in this review as biometric biomarkers (morphologic and corporal in-dexes), histological biomarkers (for tissues), molecular biomarkers (genetic) and biochemical and physiological biomarkers (both at the cellular and molecular levels). Following this classification, the most used biomarkers were biochemical and physiological biomarkers, due to the great advantages and information that they provide. It is of utmost importance to set guidelines and referenced threshold values for each biomarker to allow the early environmental diagnosis and integrated evaluation of harmful pollutants effects. Keywords: Biomarkers, environmental assessment, America.