Coral reef ecosystems in the Persian Gulf are frequently exposed to crude oil spills. We investigated benthic bacterial and eukaryote community structures at such coral reef sites subjected to different degrees of polycyclic aromatic hydrocarbon (PAH) pollution using environmental DNA (eDNA) metabarcoding. Both bacterial and eukaryote communities responded with pronounced shifts to crude oil pollution and distinguished control sites, moderately and heavily impacted sites with significant confidentiality. The observed community patterns were predominantly driven by Alphaproteobacteria and metazoans. Among these, we identified individual genera that were previously linked to oil spill stress, but also taxa, for which a link to hydrocarbon still remains to be established. Considering the lack of an early-warning system for the environmental status of coral reef ecosystems exposed to frequent crude-oil spills, our results encourage further research towards the development of an eDNA-based biomonitoring tool that exploits benthic bacterial and eukaryote communities as bioindicators.

The habitat of the endangered southern resident killer whale (SRKW) overlaps major international shipping lanes near the Port of Vancouver, British Columbia. Shipping is a dominant source of underwater noise, which can hinder SRKW key life functions. To reduce environmental pressure on the SRKWs, Vancouver Fraser Port Authority offers incentives for quieter ships. However, the absence of a widely accepted underwater radiated noise (URN) measurement procedure hinders the determination of relative quietness. We review URN measurement procedures, summarizing results to date from two Canadian-led projects aimed at improving harmonization of shallow-water URN measurement procedures: One supports the International Organization for Standardization (ISO) in the development of a URN measurement standard; the other supports the alignment of URN measurement procedures developed by ship classification societies. Weaknesses in conventional shallow-water URN metrics are identified, and two alternative metrics proposed. Optimal shallow-water measurement geometry is identified.

In this study, we evaluated the combined effects of exposure to BP3 (at an environmentally relevant concentration of 1 μg/L) with temperature increasing (24 °C) in the marine bivalve Amarilladesma mactroides. The BP3 (1 μg/L) at 20 °C increased ROS and antioxidants in the digestive glands of clams, without causing significant effect on lipid peroxidation (LPO). However, at high temperature (24 °C), BP3 suppressed increases in antioxidant defenses, mainly glutathione peroxidase, lead to a rise in LPO in the digestive gland, however this condition increased hemocyte viability. The Integrated Biological Responses (IBR) approach show that temperature influences BP3 effects, as the highest score was observed in animals exposed to 1 μg/L of BP3 at 20 °C (9.35), while the lowest was observed in BP3 group at 24 °C (1.02). These results draw attention to the harmful effects of BP3 on bivalves, especially in a scenario of thermal stress.

Besides being food and a refuge to marine species, macroalgae are a powerful and renewable economic resource. However, they may introduce microplastics (MPs) in the trophic chain. We developed a reliable analytical method to characterize and quantify MPs in common and edible macroalgae. Several digestion methods and filters, along with various measurement options, were studied. A new enzymatic-oxidative protocol with a unique final filtration was selected and validated with a mixture of 5 commercial macroalgae (Undaria pinnatifida spp, Porphyra spp, Ulva spp, Laminaria ochroleuca and Himanthalia elongate). Further, it was shown that washing the macroalgae to release MPs is suboptimal and the potential adhesion of MPs to macroalgae was evaluated. A filter subsampling strategy that scans 33.64 % of its surface reduced the time required to characterize <70 μm particles and fibres directly on the 47 mm diameter filter using an IR microscope (1 sample/day).

The accumulation of drift organisms (Arribadas, constituted by benthic microalgae, macroalgae and bryozoans) on Central Beach in Balneário Camboriú (SC) has drawn attention since the early 2000s. However, historical surveys suggest an ancient phenomenon that has been increasing in intensity, promoted by urbanization and the eutrophication of the bay in recent years, leading to changes in the taxonomic composition. Previously, these Arribadas were comprised of two species of benthic microalgae (Amphitetras antediluviana and Biddulphia biddulphiana) and the bryozoan Arbocuspis ramosa. However, since 2019, a substantial increase in biomass has been observed on the beach and the dominance of the macroalgae Bryopsis plumosa strongly suggests an increase in the load of organic matter and nutrients in the bay. Recently (2022) the presence of a new invasive bryozoan species (Amathia alternata) was detected, highlighting the need to continue investigating the Arribadas to monitor the ecological evolution of this process.

Microplastics (MPs) are accessible for organisms with active filter feeding strategies, as are many marine molluscs, which live attached or semi-buried in sediments. In the present study, MPs (from 0.02 to 5 mm) concentration, morphology, and composition were determined in consumed mollusc species of the Catalan coast (NW Mediterranean Sea). Microplastic concentrations, morphologic characteristics and composition were studied according to species, catchment zones and depuration condition. Finally, human intake of MPs through molluscs' consumption was determined. >2300 individuals were analysed, being 1460 MPs extracted and their size, and polymeric composition registered. Big oysters and mussels showed the highest MPs concentration by individual, with levels of 22.8 ± 14.4 and 18.6 ± 23.0 MPs/individual, respectively. Mean annual MPs (≥20 μm) consumption for adult population was estimated in 8103 MPs/year, with a 95th percentile of 19,418 MPs/year. It suggests that the consumption of molluscs is an important route of MPs exposure for the Catalan population.

This study aimed to assess the combined effects of ocean acidification (OA) and pollution to the polychaete Syllis prolifera inhabiting the CO₂ vent system of the Castello Aragonese (Ischia Island, Italy). We investigated the basal activities of antioxidant enzymes in organisms from the acidified site and from an ambient-pH control site in two different periods of the year. Results showed a limited influence of acidified conditions on the functionality of the antioxidant system. We then investigated the responsiveness of individuals living inside the CO₂ vent compared to those from the control to face exposure to acetone and copper. Results highlighted a higher susceptibility of organisms from the vent to acetone and a different response of antioxidant enzymes in individuals from the two sites. Conversely, a higher tolerance to copper was observed in polychaetes from the acidified-site with respect to controls, but any significant oxidative stress was induced at sublethal concentrations.

A novel adsorbent, 3-phenyl-1-(2-pyridyl)thiourea (PPTU) was synthesized and its adsorption capabilities were studied for Cu(II), Cd(II), Ni(II), Pb(II) and Fe(II) cations in the waters such as tap and polluted seawaters. The kinetics, Langmuir and Freundlich isotherms were discussed related to the adsorptions. The adsorption capacities of PPTU were found 9.4; 12.6; 90.9; 57.1 and 30.4 mg g⁻¹ and preconcentration with PPTU including the FAAS step yielded the LOQ values 0.46; 2.65; 1.12; 2.65 and 1.72 ng mL⁻¹ for Cu(II), Cd(II), Ni(II), Pb(II) and Fe(II), respectively. The adsorbent after the elutions and washings could be reused three times in the next adsorptions. The interferences on the adsorptions arising from the major cations of the seawater and the usability of PPTU for interested metals in the seawater were discussed. The proposed method is simple with highly efficient and green preconcentration procedure for trace analysis of the target metal ions.

This study focuses on determination of quantity, shape, size and polymer types of microplastics in Pacific oysters (Crassostrea gigas) cultured in Danang Bay, Vietnam. Visual verification and chemical identification of microplastics was carried out by μFT-IR spectra using Nicolet iN10 MX Infrared Imaging Microscope. The average abundance of microplastic in oysters was 1.88 ± 1.58 particles/g (wet weight) and 18.54 ± 10.08 particles/individual. The prevalent shape of microplastics included three main forms as fragment, fiber and bead corresponding to 73.71; 25.84 and 0.45%, respectively. Additionally, the size of microplastics was a range of 22.4–1318.8 μm, and the most common size was less than 100 μm, accounted for 77.30%. Fifteen polymer types were detected while Nylon was the most abundant polymer type with 50.56%. In this study, microplastics accumulation with their abundance and polymeric structures could be considered as reliable evidence for further studies on assessment of their potential risk to human health.

We examined microplastics (MP) in two commercially important dried fish, Bombay duck (Harpadon nehereus) and ribbon fish (Trichiurus lepturus), collected from two sites on the Bay of Bengal (Cox's Bazar and Kuakata). The number of MP found in dried Bombay duck and ribbon fish from Kuakata was significantly higher (41.33 g⁻¹ and 46.00 g⁻¹, respectively) than the MP present in samples collected from Cox's Bazar (28.54 g⁻¹ and 34.17 g⁻¹, respectively). Fibers were the most common type of MP identified in all samples (41–64%), followed by fragments (22–34%), microbeads (9–16%), films (3–4%), foams (1–4%), and pellets (0–2%). ATR-FTIR analysis revealed three different types of MP polymer - polyethylene (35–45%), polystyrene (20–30%) and polyamide (30–45%) in the dried fish samples. The study confirms the presence of high MP loads in dried fish from the Bay of Bengal, with high potential of trophic transfer of MP to the human body.