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In this short note, we present new results on stress on stress response measurements in both farmed and wild Mediterranean mussels from the town of Sozopol, Bulgaria, collected in the summer of 2024 (August) and compare them with our previous results for the winter and spring season. [ABSTRACT FROM AUTHOR]

Simple Summary: The multiple impacts of polycylic aromatic hydrocarbon on the aquatic invertebrates were rarely assessed in a chronic way and multiple-species experiments, despite the clear advantage of better mimicking natural conditions compared to traditional acute and single-species-focused toxicological experiments. The application of such an approach is essential to lower the health risks for populations that regularly consume seafood. The data presented herein supported the use of Mytilus galloprovincyalis and Ruditapes decussatus as bioindicators of phenanthrene in water and/or sediment and proved the efficacy of the biomarkers' assessment and molecular modelling in determining environmental thresholds and policies for governments. The aim of the current study was to assess the multifaceted effects of the polycylic aromatic hydrocarbon phenanthrene, mainly used in the colouring, explosive, and pharmaceutical industries, on the physiology of two bivalve species with economic value as seafood, namely, the Mediterranean mussel Mytilus galloprovincyalis and the European clam Ruditapes decussatus. The current study assessed how the phenanthrene affected several biomarkers and biometric endpoints in both bivalves, based on an in vivo experiment in silico approach. The bivalves were exposed during four time slots (i.e., 7, 15, 21, and 28 days) to two concentrations of phenanthrene in water (50 µg/L and 100 µg/L). For the clam R. decussatus, an additional contamination of sediment was applied due their typical benthic lifestyle (50 µg/kg and 100 µg/kg). The phenanthrene significantly reduced the ability of bivalves to tolerate desiccation and their Median Lethal Time, and also inhibited the activity of the enzyme acetylcholinesterase in a time-dependent manner. The activity of catalase indicated that bivalves also experienced oxidative stress during the first 21 days of the experiment. The significant decline in catalase activity observed during the last week of the experiment for the mussel M. galloprovincyalis supported a depletion of enzymes caused by the phenanthrene. The phenanthrene has also toxicokinetic and toxicodynamic properties, as assessed by the in silico approach. Overall, the results obtained suggest that the bivalves Ruditapes decussatus and M. galloprovincyalis can be used as a sentinel species in monitoring studies to assess the environmental impact of phenanthene in marine ecosystems. The significance of our findings is based on the fact that in ecotoxicology, little is known about the chronic effects, the simultaneous use of multiple species as bioindicators, and the interactions molecular modelling. [ABSTRACT FROM AUTHOR]

Abstract Intertidal sessile organisms constitute through their life history unintended stress recorders. This study focuses on the impact of pollution on Mytilus edulis ability to cope with an additional stress. For this purpose, two acclimation stages to different temperatures were conducted before an acute stress exposure in mussels collected from a heavily polluted site. Gill proteomes were analyzed by 2DE and regulated proteins identified. Massive mortality was observed for organisms acclimated to colder temperatures. Despite this major difference, both groups shared a common response with a strong representation of proteoforms corresponding to "folding, sorting and degradation" processes. Nevertheless, surviving mussels exhibit a marked increase in protein degradation consistent with the observed decrease of cell defense proteins. Mussels acclimated to warmer temperature response is essentially characterized by an improved heat shock response. These results show the differential ability of mussels to face both pollution and acute heat stress, particularly for low-acclimated organisms. Graphical abstract Unlabelled Image Highlights • 2DE were carried out on contaminated mussels after acclimation and acute heat stress. • High mortality rate were observed for non-acclimated mussels. • Acclimated mussels show enhanced stress protein expressions. • Surviving mussels exhibited a main distress signal associated with truncated proteins. [ABSTRACT FROM AUTHOR]

This study investigated whether general stress biomarkers in mussels can be applied as common first-tier biomarkers in regional biomonitoring programmes in the North Sea (including Iceland) and western Mediterranean Sea. Stress on Stress (SoS) and lysosomal membrane stability (LMS) biomarkers were analysed in resident mussels ( Mytilus sp.) from 8 coastal sites and in transplanted mussels ( Mytilus galloprovincialis) from two Spanish Mediterranean coastal sites. The assessment of results, as input to pollution monitoring strategies, was performed jointly for LMS and SoS data from the two regions. Contaminant body burden of the mussels was compared with biomarker results. The results demonstrated that these two general and non-expensive stress biomarkers in mussel can be applied throughout European waters, providing a cost-effective and harmonised approach to screen contaminant-related biological effects within the framework of wide-scale pollution biomonitoring programmes, such as that proposed by the European Union, i.e. the Marine Strategy Framework Directive. [ABSTRACT FROM AUTHOR]

Abstract: Polycyclic aromatic hydrocarbons (PAHs) constituents, such as phenanthrene (PH) and anthracene (AN), are considered toxic for marine organisms, including bivalve mollusks. The present study showed that the perturbation of health status in mussels, as well as their inability to survive in air (stress on stress response), following exposure to either PH or AN (at a final concentration of 0.1mg/L respectively), and a mixture of them (ration 1:1, at a final concentration of 0.2mg/L) for 7days, is probably related with alterations occurred in their haemocytes. According to the present study, PH and AN, either alone or in a mixture, could induce elevated levels of superoxide anions (•O2 −) within haemocytes of mussels, thus leading to immune susceptibility as indicated by the increased levels of cell death and the elevated levels of lysosomal membrane acid phosphatase (AcP) activity, probably occurred via its overproduction or its release into the cytosol after lysosomal membrane destabilisation. PAH-mediated oxidative and genotoxic effects, indicated by the increased levels of both lipid peroxidation (MDA content) and nuclear abnormalities (MN test) could be related with haemocytes'' inability to overcome free radical generation, thus leading to attenuation of general health status, before other disturbances, such as death, occur. [Copyright &y& Elsevier]

The aim of this work was to detect in vivo effects of cadmium on marine organisms Cerastoderma glaucum and to determine the optimal conditions for the metallothionein-like protein (MTLP) induction in this species under laboratory conditions. The cockles Cerastoderma glaucum were exposed in vivo to different cadmium concentrations (50, 75, 100 and 150 µg L-1). Stress on stress test, cadmium, metallothionein-like protein (MTLP), malondialdehyde (MDA) and protein levels were measured after 5, 10, 15 and 20 days of metal exposure. The results showed that the CdCl2 concentrations of 50 µg L-1 for 15 days as well as 150 µg L-1 for 10 days provoked the highest MTLP induction. Nevertheless, the results obtained by the MDA, protein quantification and the stress on stress test showed that animals exposed to 50 µg L-1 for 15 days were in a better health status than those exposed to 150 µg L-1 CdCl2 for 10 days. [ABSTRACT FROM AUTHOR]