Anthropogenic sound can affect fish behaviour and physiology which may affect their well-being. However, it remains a major challenge to translate such effects to consequences for fitness at an individual and population level. For this, energy budget models have been developed, but suitable data to parametrize these models are lacking. A first step towards such parametrization concerns the objective quantification of behavioural states at high resolution. We experimentally exposed individual Atlantic cod (Gadus morhua) in a net pen to the playback of seismic airgun sounds. We demonstrated that individual cod in the net pen did not change their swimming patterns immediately at the onset of the sound exposure. However, several individuals changed their time spent in three different behavioural states during the 1 h exposure. This may be translated to changes in energy expenditure and provide suitable input for energy budget models that allow predictions about fitness and population consequences.

Trace elements can be accumulated from coastal environment by aquatic organisms from their food and be transferred throughout the food webs. Studying the effects of salinity on the trophic transfer of trace elements in a euryhaline fish, able to deal with large variations in salinity, is therefore key to understand their dynamics in aquatic environments. In this context, we investigated the potential influence of salinity on the trophic transfer of two essential elements (Mn and Zn) in the euryhaline fish, the turbot Scophthalmus maximus using radiotracer techniques. After acclimation to three salinities (10, 25 and 38), turbots were fed with radiolabelled pellets (⁵⁴Mn and ⁶⁵Zn). Kinetic parameters of depuration were determined after a 21-d period and trophic transfer factors were calculated. Trophic transfer of Mn at the highest salinity was significantly lower than for the other conditions whereas salinity did not significantly influenced Zn trophic transfer. Differences in the processes involved in the regulation (homeostasis) of the two tested trace elements may explain the contrasting influence of seawater salinity for Mn and Zn.

Inconsistencies in microplastic quantification are a problem in current microplastic research, leading to difficulties in inter-study comparability. This study proposes a guideline for consistent quantification of microplastic distributions. It contains specific recommendations on how to quantify common microplastic particle parameters, such as size or shape. These recommendations are based on how reliably a parameter can be measured and its importance for inter-study comparability. Furthermore, our study proposes a multidimensional vector approach, where one vector contains the information for the microplastic distribution in one sample. In this way geometric and statistical means can be used to quantitatively compare different studies. In particular, in combination with our proposed quantification procedure, a meaningful comparison of microplastic distributions across different studies becomes possible. Ultimately, this allows comparable long-term and global scale assessments, as well as the development of modeling approaches.

We report on concentrations of polybrominated diphenylethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB) measured in the adipose fins of returning adult Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) to the river Tees in the Northeast of England. Overall, higher concentrations of these contaminants were found in sea trout samples, where detected congeners reflected the more widely used commercial formulations, in particular for the PBDEs. Our results suggest that these fish could be bioaccumulating persistent organic pollutants via diet during their migratory routes (North Sea and the Norwegian Sea) and, in addition, some level of re-mobilisation of these compounds could still be occurring in the UK eastern coastal areas. The use of adipose fin of returning salmonids could be further developed as a non-lethal approach to assess whether persistent contaminants are being accumulated during the juvenile to adult phase of salmonids originating from UK rivers.

This study evaluates the potential area and the key environmental factors supporting Sargassum bed restoration (SBR) in the highly turbid northwestern Arabian Gulf where rapid coastal development impinges on the marine ecosystem functioning. Water depth was a primary environmental factor governing the distribution of the subtidal macroalgae beds in these turbid waters. The relationship between Sargassum coverage and water depth measured by an echo sounder indicated optimal water depths where the maximum coverage was observed. The availability of stable hard substrate was another key factor introducing heterogeneity in Sargassum coverage. Potential area for the SBR estimated based on the optimal depths was 4.26 km², whereas only 50% of the potential area (2.19 km²) was currently vegetated due to the absence of hard substrate. The outcomes of this study offer beneficial information toward implementation of the SBR as a part of mitigation measures in future coastal development plans in the region.

Exposure to oil can have long-term impacts on migratory birds. Following the 2010 Deepwater Horizon blowout in the Gulf of Mexico (GOM), we investigated potential impacts of oil exposure on a population of northern gannets (Morus bassanus) that breed on Bonaventure Island (Québec, Canada) and winter in GOM and along the U.S. Atlantic coast (AC). Blood and feather samples were collected from adults previously equipped with geolocators to determine wintering locations. Parent and alkylated polycyclic aromatic hydrocarbons (PAHs); trace metals; stable isotopes of carbon, nitrogen, and hydrogen; and immune, thyroid, steroid, retinoid, and genetic endpoints were measured. PAH and trace metal concentrations did not differ between gannets using different wintering sites. Feather stable isotope values varied significantly between birds from different wintering locations. Gannets wintering in GOM showed higher feather corticosterone and plasma thyroid hormone levels, which may indicate increased energetic demands and/or greater exposure to environmental stressors.

The majority of aquatic toxicity data for petroleum products has been limited to a few intensively studied crude oils and Corexit chemical dispersants, and acute toxicity testing in two standard estuarine test species: mysids (Americamysis bahia) and inland silversides (Menidia beryllina). This study compared the toxicity of two chemical dispersants commonly stock piled for spill response (Corexit EC9500A®, Finasol®OSR 52), three less studied agents (Accell Clean®DWD dispersant; CytoSol® surface washing agent; Gelco200® solidifier), and three crude oils differing in hydrocarbon composition (Dorado, Endicott, Alaska North Slope). Consistent with listings on the U.S. National Contingency Plan Product Schedule, general rank order toxicity was greatest for dispersants and lowest for the solidifier. The results indicate that freshwater species can have similar sensitivity as the conventionally tested mysids and silversides, and that the sea urchin (Arbacia punctulata) appears to be a reasonable addition to increase taxa diversity in standardized oil agent testing.

This study aims to determine the background values for metals in the Suape estuarine system, Brazil, and to identify contamination caused by anthropogenic sources. Two cores were sampled. Sedimentation rates and metal content were analysed. The Al-normalized method was used to infer the background values, and to identify anthropic influences, the enrichment and contamination factors and the geoaccumulation index were employed. The results revealed an Mn, Ni, Zn, Ga, Pb, Sr, Ti, Mg, V and Fe content (mg kg⁻¹) of 101.8, 5.7, 24.4, 8.3, 14.5, 41.9, 2744.6, 4581, 14.9 and ~ 1% respectively. After the installation of the Suape port, an increase in metal contents and in fluxes were recorded. Increases in Zn, Ga, V and Pb are supported by the indexes showing moderate contamination, enrichment and suggest an area moderately polluted. The other studied metals do not reflect an anthropogenic impact, with low values of contamination, enrichment factors and geoaccumulation indexes.

Laboratories from 14 countries (with different levels of expertise in radionuclide measurements and ²¹⁰Pb dating) participated in an interlaboratory comparison exercise (ILC) related to the application of ²¹⁰Pb sediment dating technique within the framework of the IAEA Coordinated Research Project.The laboratories were provided with samples from a composite sediment core and were required to provide massic activities of several radionuclides and an age versus depth model from the obtained results, using the most suitable ²¹⁰Pb dating model. Massic concentrations of Zn and Cu were also determined to be used for chronology validation.The ILC results indicated good analytical performances while the dating results didn't demonstrate the same degree of competence in part due to the different experience in dating of the participant laboratories. The ILC exercise enabled evaluation of the difficulties faced by laboratories implementing ²¹⁰Pb dating methods and identified some limitations in providing reliable chronologies.

Several studies have shown the ubiquitousness of microplastics across ecosystems worldwide including significant amounts in beach sand. In Thailand, however, there is a lack of studies about the microplastic pollution of beaches. This study aimed to quantify microplastics at the high-tide line of 21 beaches along the eastern Gulf of Thailand. Observed amounts ranged from 420 to >200,000 counts/kg. Anthropogenic and environmental factors affect distribution and amount of microplastics. Tide-dominated beaches and beach sections protected by beachrocks exhibit higher microplastic amounts due to lesser hydrodynamics. While human activities have a visible impact, in some cases environmental factors seem to predominate. Despite effective protection efforts led by the government and NGOs, our study shows that the substantial microplastic pollution of beach sand requires a proper management system with appropriate laws and regulations, and a public awareness campaign to reduce effects of microplastics on organisms and their ecosystems.