Effects of ferroelectric oxides of barium strontium titanate (Ba0.85Sr0.15TiO3) nanoparticles on Ruditapes decussatus assessed through chemical, physiological, and biochemical methods

Metabolic variation and oxidative stress responses of clams (Ruditapes philippinarum) perturbed by ofloxacin exposure

Ofloxacin (OFL), one of the most widely used fluoroquinolone antibiotics, has been frequently detected in marine environments. Nonetheless, researchers are yet to focus on the effects of OFL on the benthos. In the present study, marine clams (Ruditapes philippinarum) were exposed to OFL (0.5, 50, and 500 μg/L) for 14 d, followed by a 7 d depuration period. The accumulation of OFL, antioxidative defense responses, neurotoxicity, burrowing behavior, and metabolomic changes in clams were evaluated. The results indicated that OFL could accumulate in clams, albeit with a low bioaccumulation capacity. The intermediate (50 μg/L) and high (500 μg/L) levels of OFL induced significant antioxidative responses in the gills and digestive glands of clams, mainly manifesting as the inhibition of catalase activities and the induction of superoxide dismutase and glutathione S-transferase activities, which ultimately elevated the content of malondialdehyde, causing oxidative damage. Furthermore, the significant induction of acetylcholinesterase activities was observed, coinciding with a significant increase in burrowing rates of clams. The high level of OFL affected glycerophospholipid, arachidonic acid, steroid hormone biosynthesis, unsaturated fatty acids biosynthesis, and glycolysis/glycogenesis metabolism. In conclusion, this study has contributed to the understanding of the physiological and biochemical effects and molecular toxicity mechanisms of OFL to marine bivalves.

Experimental and computational assessment of Antiparkinson Medication effects on meiofauna: Case study of Benserazide and Trihexyphenidyl

Two concentrations (6.25 and 1.25 mg/L) were used for two Parkinson's disease medications, Benserazide, and Trihexyphenidyl, to test their effects on the meiobenthic nematofauna. It is predicted that these highly hydrosoluble drugs will end up in marine environments. The results showed that both medications when added alone, induced (i) important changes in the numbers and (ii) taxonomic composition. The impact of Benserazide and Trihexyphenidyl was also reflected in the (iii) functional traits of nematofauna, with the most affected categories following exposure being the trophic group 1B, the clavate tails, the circular amphids, the c-p2 life history, and the body length of 1-2 mm. These results were supported by the molecular interactions of the studied drugs with both GLD-3 and SDP proteins of Caenorhabditis elegans. (iv) The mixtures of both drugs did not show any changes in the nematode communities, suggesting that no synergistic or antagonistic interactions exist between them.

Biochemical and physiological alterations caused by Diuron and Triclosan in mussels (Mytilus galloprovincialis)

The rise in the utilization of pesticides within industrial and agricultural practices has been linked to the occurrence of these substances in aquatic environments. The objective of this work was to evaluate the uptake and adverse impacts of Diuron (Di) and Triclosan (TCS) on the mussel species Mytilus galloprovincialis. To accomplish this, the accumulation and toxicity of these pesticides were gauged following a brief period of exposure spanning 14 days, during which the mussels were subjected to two concentrations (50 and 100 μg/L) of each substance that are ecologically relevant. Chemical analysis of Di and TCS within gills and digestive gland showed that these pesticides could be accumulated in mussel's tissues. In addition, Di and TCS are preferably accumulated in digestive gland. Measured biomarkers included physiological parameters (filtration FC and respiration RC capacity), antioxidant enzyme activities (superoxide dismutase and catalase), oxidative damage indicator (Malondialdheyde concentration) and neurotoxicity level (acetylcholinesterase activity) were evaluated in gills and digestive glands. Both pesticides were capable of altering the physiology of this species by reducing the FC and RC in concentration and chemical dependent manner. Both pesticides induced also an oxidative imbalance causing oxidative stress. The high considered concentration exceeded the antioxidant defense capacity of the mussel and lead to membrane lipid peroxidation that resulted in cell damage. Finally, the two pesticides tested were capable of interacting with the neuromuscular barrier leading to neurotoxicity in mussel's tissues by inhibiting acetylcholinesterase. The ecotoxicological effect depended on the concentration and the chemical nature of the contaminant. Obtained results revealed also that the Di may exert toxic effects on M. galloprovincialis even at relatively low concentrations compared to TCS. In conclusion, this study presents innovative insights into the possible risks posed by Diuron (Di) and Triclosan (TCS) to the marine ecosystem. Moreover, it contributes essential data to the toxicological database necessary for developing proactive environmental protection measures.

Do functional traits and biochemical biomarkers of the nematode Oncholaimus campylocercoides De Coninck and Schuurmans Stekhoven, 1933 affected by fluoranthene and polystyrene microplastics? Results from a microcosm bioassay and molecular modeling

The current experiment measured the multifaceted effects of polystyrene and fluoranthene, acting alone or in a mixture, on the meiobenthic nematode species Oncholaimus campylocercoides. This Oncholaimid was first experimentally selected from an entire nematode assemblage taken from the Jeddah coasts (Saudi Arabia). Several discernible changes were found in morphometry and functional traits after exposure to single and combined treatments. An increase in the activity of the biochemical biomarkers catalase and glutathione S-transferase was also observed following the exposure of males and gravid females of O. campylocercoides to 37.5 ng fluoranthene·g-1 dry weight (DW) and 62.5 mg polystyrene·kg-1 DW paralleled by a higher vulnerability of females. Moreover, the reproduction and feeding of this species were impaired, starting from 37.5 ng fluoranthene·g-1 and 62.5 mg polystyrene·kg-1, respectively. These results have been confirmed by good binding affinities and molecular interactions of fluoranthene and polystyrene with both GLD-3 and SDP receptors.

Ecotoxicity of chrysene and phenanthrene on meiobenthic nematodes with a case study of Terschellingia longicaudata: Taxonomics, toxicokinetics, and molecular interactions modelling

Polycyclic aromatic hydrocarbons (PAHs) are toxic for humans and marine fauna alike. The current study assessed the impact of PAHs on the migratory behaviour of meiobenthic nematodes collected from the Bizerte lagoon, Tunisia. The experiment lasted for 15 days and was carried in open microcosms, which comprised a lower, contaminated and an upper, uncontaminated compartment. Three treatments were used, for each of them an untreated control was set up: sediment contaminated with chrysene (116 ng g^-1 dry weight (DW), with phenanthrene (116 ng g^-1 DW) and a mixture of both. The results showed a significant decrease in diversty and abundance in the lower, contaminated compartments compared to the upper zones. The results also highlighted that under an increased stress some species progressively increased in number, these were considered PAH-tolerant species such as Odontophora villoti, some others had an occasionally increased in number were considered as opportunistic species, such as Paracomesoma dubium and the species that showed a progressive decreased in number, such as Metoncholaimus pristiurus and Steineria sp., Terschellingia. longicaudata, and Oncholaimellus sp. were classified as PAH-sensitive. Moreover, an increase in the activity of biochemical biomarkers was observed following the exposure of males and gravid females of T. longicaudata to 29, 58 and 87 ng g^-1 DW of chrysene and phenanthrene paralleled by a higher vulnerability of the latter demographic category. Besides, a significant decrease in fertility of females and an increase in pharyngeal sucking power were observed for both types of PAHs considered. The sex ratio was also significantly imbalanced in the favor of males, which suggest that chrysene and phenanthrene affect also the hormone system of T. longicaudata. The high affinities of these PAHs and their molecular interactions with both germ line development protein 3 (GLD-3) and sex-determining protein (SDP) may justify these results and explain the toxicokinetic attributes.

Effects of benzo(a)pyrene on meiobenthic assemblage and biochemical biomarkers in an Oncholaimus campylocercoides (Nematoda) microcosm

A microcosm experiment was carried out to determine how benzo(a)pyrene (BaP) may affect marine meiofauna community, with a main emphasis on nematode structure and functional traits. Three increasing concentrations of BaP (i.e. 100, 200 and 300 ng/l, respectively) were used for 30 days. The results revealed a gradual decrease in the abundance of all meiobenthic groups (i.e. nematodes, copepods, amphipods, polychaetes and oligochaetes), except for isopods. Starting at concentrations of 200 and 300 ng/l BaP, respectively, significant changes were observed at community level. At taxonomic level, the nematode communities were dominated at the start of the experiment and also after being exposed or not to BaP by Odontophora villoti, explicable through its high ecologic ubiquity and the presence of well-developed chemosensory organs (i.e. amphids), which potentially increased the avoidance reaction following exposure to this hydrocarbon. Moreover, changes in the activity of several biochemical biomarkers (i.e. catalase 'CAT', gluthatione S-transferase 'GST', and ethoxyresorufin-O-deethylase 'EROD') were observed in the nematode species Oncholaimus campylocercoides, paralleled by significant decreases in CAT activity for non-gravid females compared to controls at concentrations of 25 ng/l BaP and associated with significant increase in GST and EROD activities for both types of individuals.