Biomonitoring of environmental stress in Pollicipes pollicipes from the northern coast of Portugal: a non-destructive approach using haemolymph

The goose barnacle Pollicipes pollicipes as a tool for trace metal biomonitoring and health risk assessment for human consumers in northwestern Atlantic coast of Morocco

The bioaccumulation of trace metals Cd, Cr, Cu, Fe, and Zn in soft tissues of the barnacle Pollicipes pollicipes was investigated seasonally along the Atlantic coast of northwestern Morocco. Average concentrations (μg g-1 dry weight) exhibited a decreasing order: Fe (548.15 ± 132.43) > Zn (430.80 ± 181.68) > Cd (17.46 ± 9.99) > Cu (7.72 ± 1.26) > Cr (3.12 ± 0.80), with the highest levels during wet seasons. The "Metal Pollution Index" and "Individual Multimetal Bioaccumulation Index" revealed a substantial barnacle contamination in industrialized areas. Additionally, Cd and Zn concentrations surpassed permissible guideline limits. While the "Target Hazard Quotient" and "Hazard Index" unveiled no significant health risks associated with barnacle consumption for humans, Cd posed potential risks, particularly for children consuming barnacles from polluted locations. Regarding the "Maximum Safe Consumption", Cd demonstrated potential harm across all sex and age groups. These findings contribute valuable data on the safety of barnacle consumption, marking the initial assessment of such risks in Morocco. The study offers evidence of metal pollution occurrence and proposes the barnacle species as a reliable biomonitor of trace metal bioavailabilities in marine coastal areas. To our knowledge, this investigation is the first comprehensive report of metal contamination biomonitoring using barnacles from Moroccan Atlantic waters.

Under pressure: Assessing the ecological boundaries of the epipelagic goose barnacle Lepas anatifera using ocean gliders and laboratory experiments

Epipelagic barnacles have been considered good bioindicators since they are abundant and broadly distributed but with apparent tolerance restrictions to temperature and salinity, and also bioaccumulate pollutants. However, Lepas anatifera was found attached to the oceanic gliders, thriving through drastic and unreported environmental fluctuations. This study aimed to assess the resistance and oxidative stress responses of L. anatifera collected from gliders and attached to floating litter to temperature, salinity, and pressure. Barnacles withstood all tested pressure, temperature, and salinity ranges, except the extreme salt concentration. The activities of antioxidant enzymes - catalase and superoxide dismutase - were significantly increased under high temperature, high pressure, and low salinity. Malondialdehyde levels significantly increased only under high pressure. In conclusion, L. anatifera can be considered resistant organisms to extreme environmental changes. However, the instauration of oxidative stress under certain circumstances makes them vulnerable to predicted future trends in marine environments.

Acetylcholinesterase activity in muscle tissue of Norway lobster Nephrops norvegicus: Importance of body size, season, sex and naturally occurring metals

The aim of the present study was to determine the levels of acetylcholinesterase (AChE) activity in the tail muscle tissue of wild populations of Nephrops norvegicus from the Northern Adriatic, and correlate it to body size, seasons, sex and the content of mercury, arsenic, cadmium, lead and copper. The animals of both sexes were collected in spring and autumn from two relatively distant fishing grounds. A marked variability of muscle AChE activity was found (0.49 to 11.22 nmol/min/mg prot.), displaying the opposite seasonal trend between two sampling sites. Small, but significant negative correlation has been found between AChE activity and carapace length (rs = - 0.35, p < 0.05). Data reported here provide an essential baseline for future studies of neurotoxicity in crustaceans. The study highlights the necessity for continuous monitoring of potentially toxic metals in edible marine species to avoid possible repercussions of seafood consumption on human health.

Evaluation of single and combined effects of two pharmaceuticals on the marine gastropod Phorcus lineatus enzymatic activity under two different exposure periods

Pharmaceutical drugs are among the most used chemicals for human and veterinary medicines, aquaculture and agriculture. Pharmaceuticals are environmentally persistent, biologically active molecules, thereby having the potential to exert biological effects on non-target species. Among the most used pharmaceuticals, one may find salicylic acid (SA), a non-steroid anti-inflammatory drug (NSAID) that acts by inhibiting the enzymes cyclooxigenases; it is also possible to identify acetazolamide (ACZ), a diuretic that acts by inhibiting the activity of carbonic anhydrase (CA). In this work, the effects of both single and combined effects of these drugs were assessed on the marine gastropod Phorcus lineatus, by measuring key enzymatic activities, namely carbonic anhydrase (CA) and cyclooxygenase (COX), under two different exposure periods (14 and 28 days). We observed no straightforward pattern of enzymatic response in all treatments of both pharmaceuticals, on both analyzed tissues (gut and gills), and for both exposure regimes. We assume that this species is not responsive to the hereby tested pharmaceuticals, a finding that may be due to general mechanisms of response to adverse conditions, such as reduction of metabolism, of heart rate, of filtration rates, and to the increase production of mucus. All these functional adaptations can mitigate the deleterious effects caused by adverse conditions, without triggering biochemical responses. In conclusion, the species P. lineatus seems not to be sensitive in terms of these specific enzymatic pathways to these contaminants, under the adopted conditions.

Preliminary results on the uptake and biochemical response to water-exposure of Tamiflu® (oseltamivir phosphate) in two marine bivalves

Tamiflu® (oseltamivir phosphate, OST) is an antiviral drug used for the pandemic treatment of avian influenza but few data are available regarding its toxicity. It should be noted that acute adverse responses are not likely to occur due to low environmental presence of this drug. Nonetheless, water concentration levels of this compound may reach the µg/L range under influenza episodes. Bivalves are reliable sentinels of chemical exposure due to their low metabolism; however, biotransformation of drugs does occur in these aquatic invertebrates. Two species of bivalves, namely mussels Mytilus galloprovincialis and clams Ruditapes philippinarum, were exposed for 48 h to 100 µg/L OST. Hemolymph from control and treated bivalves was withdrawn and the presence of OST and its metabolite oseltamivir carboxylate (OST-C) determined by LC-MS/MS. Gills and digestive gland were excised from control and exposed bivalves and carboxylesterase (CE) activities measured using different substrates. In addition, antioxidant defences and lipid peroxidation levels were determined. Higher metabolism of OST seemed to occur in mussels, since both OST and OST-C were found in hemolymph, whereas in clams only the parent compound was detected. In contrast, biomarker responses were more evident in exposed clams which indicate that this species may be considered as more sensitive to OST exposure. CE-related activities successfully reflected OST exposure, with substrates 1-naphthyl acetate (1NA) and 1-naphthyl butyrate (1NB) displaying the highest sensitivity in the two bivalve species. Data thus indicate the usefulness of CE-related activities as biomarkers for OST exposure in bivalves.

iTRAQ-based quantitative proteomic analysis identified Eno1 as a cadmium stress response gene in Propsilocerus akamusi (Tokunaga) hemolymph

Propsilocerus akamusi (Tokunaga) is a common species of midge in Siberia, Japan, and China and an important prey species for fish and aquatic birds. Furthermore, this species has been shown to have an extraordinary capacity to resist cadmium (Cd) toxicity. In this study, isobaric tags for relative and absolute quantitation (iTRAQ) coupled liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to analyze relative changes in the P. akamusi hemolymph proteome following exposure to a sublethal concentration of Cd²⁺. The results showed that Cd²⁺ stress affects energy metabolism in P. akamusi. After examining the differentially expressed proteins (DEPs), only one up-regulated protein associated with metabolism, α-enolase (Eno1) was identified and further isolated and characterized. Sequence alignments showed that the deduced P. akamusi Eno1 amino acid sequence is highly conserved, with similarities of 77-95% noted when compared to other Dipteran Eno1 sequences. Furthermore, prolonged Cd²⁺ exposure impacted Eno1 transcription, protein expression and enzyme activity levels. These results suggest that Eno1 may play a role in the response to Cd²⁺ stress in P. akamusi.

Effects of zinc pyrithione on biochemical parameters of the freshwater Asian clam Corbicula fluminea

Zinc pyrithione (ZnPT) is an organometallic biocide with bactericide, algaecide, and fungicide activity. Considering this biological activity, ZnPT has been used in anti-fouling paints, and also in human therapeutics and cosmetics, in shampoos to treat dandruff and seborrhoea. Despite its potential uses and consequent presence in the aquatic environment, the ecotoxicological effects of ZnPT are poorly understood. This work aims to characterise the effects of ZnPT in biochemical parameters of the Asian clam, one of the most invasive bivalves known for its biofouling action in hydro-dependent industries, using a classical (LC₅₀ determination) and a biomarker-based approach (quantification of the activities of catalase, GSTs, and acetylcholinesterase, and also the muscle glycogen content). The here determined LC₅₀-96 h for zinc pyrithione was 2.17 mg/L. ZnPT caused significant increases in the activity of catalase and of cholinesterases. These findings evidence the pro-oxidative effects caused by the metabolism of ZnPT. Despite the absence of clear effects, it is important to stress that the presence of ZnPT in the wild is usually accompanied by other pyrithiones, whose co-existence can contribute to the exertion of considerable toxic effects.

Testing biomarker feasibility: a case study of Laeonereis culveri (Nereididae, Annelida) exposed to sewage contamination in a subtropical estuary

The feasibility of biomarkers to accurately detect pollution in estuaries and coastal areas appears to be overestimated in the scientific literature, and is likely stemming from a bias towards publishing only positive results. Herein, we test the applicability of antioxidant capacity and lipid peroxidation to detect potential in situ sewage impacts on a subtropical estuary. We experimentally assessed variation in malondialdehyde (MDA, an indicator of lipid peroxidation) and total antioxidant capacity against peroxyl radicals (ACAP) through transplantations of the worm Laeonereis culveri from control to sewage-polluted areas. Variations in biomarkers were more related to natural environmental variability and small-scale heterogeneity among areas than to experimental exposure to sewage. Use of oxidative stress biomarkers is promising but further experimental work under real-life conditions is necessary to further validate and establish their accuracy and feasibility for practical purposes.

Can environmental pollution by metals change genetic diversity? Ucides cordatus (Linnaeus, 1763) as a study case in Southeastern Brazilian mangroves

Industrial areas on estuarine systems are commonly affected by heavy metals, affecting all local biota. Random Amplified Polymorphic DNA (RAPD) was used to evaluate genetic diversity of Ucides cordatus at mangroves in southeastern Brazil (Juréia, J; São Vicente, SV; and Cubatão, C), with distinct pollution levels by metals. The genetic diversity of this species was compared with concentrations of metals (Cd, Pb, Cu, Cr and Hg) in the environment. A pollution gradient was confirmed (SV>C>J), with low levels detected in water, except for mercury in SV. All metals in the sediment samples were below Threshold Effect Level (TEL), without an apparent biological risk to the biota. Genetic distance was very similar between J and C, with SV occurring as an out-group. RAPD was a powerful tool to investigate the effect of metal pollution on genetic diversity of this mangrove crab, and to evaluate the conservation status of the mangrove ecosystem.