Although the presence of microplastics in marine biota has been widely recorded, extraction methods, method validation and approaches to monitoring are not standardized. In this study a method for microplastic extraction from fish guts based on a chemical alkaline digestion is presented. The average particle retrieval rate from spiked fish guts, used for method validation, was 84%. The weight and shape of the test particles (PET, PC, HD-PE) were also analysed with no noticeable changes in any particle shapes and only minor weight change in PET (2.63%). Microplastics were found in 1.8% of herrings (n=164) and in 0.9% of sprat (n=154). None of the three-spined sticklebacks (n=355) contained microplastic particles.

The aim of the present study was to verify the antimicrobial susceptibility profile and virulence factors of Vibrio parahaemolyticus isolated from water and bivalve mollusks. A high percentage of V. parahaemolyticus was isolated in natura, processed bivalves tissues, and surrounding water (75%, 20%, and 59%, respectively). The most potential virulence phenotype in V. parahaemolyticus isolates was amylase production (97%) followed by DNase (83%), phospholipase (70%), β-hemolytic activity (57%). The tdh and trh genes were not detected. Besides, a high antimicrobial resistance was observed for ampicillin (97%), minimum inhibitory concentration [MIC] = 400 μg and cephalothin (93%, MIC ≤ 100 μg). The absence of expression of tdh and trh virulence genes excluded the toxigenic potential of V. parahaemolyticus isolates; however, the high prevalence of antimicrobial resistance among the environmental strains is a risk to human health.

Estuarine oxygen depletion is one of the worldwide problems, which is caused by the freshwater-input-derived severe stratification and high nutrients loading. In this study we presented the horizontal and vertical distributions of dissolved oxygen (DO) in the Pearl River estuary, together with temperature, salinity, chlorophyll a concentration and heterotrophic bacteria abundance obtained from two cruises during the summer (wet) and winter (dry) periods of 2015. In surface water, the DO level in the summer period was lower and varied greater, as compared to the winter period. The DO remained unsaturated in the summer period if salinity is <12 and saturated if salinity is >12; while in the winter period it remained saturated throughout the estuary. In subsurface (>5m) water, the DO level varied from 0.71 to 6.65mgL−1 and from 6.58 to 8.20mgL−1 in the summer and winter periods, respectively. Particularly, we observed an area of ~1500km2 low DO zone in the subsurface water with a threshold of 4mgDOL−1 during this summer period, that located at the fresh- and saline-water intersection where is characterized with severe stratification and high heterotrophic bacteria abundance. In addition, our results indicate that spatial DO variability in surface water was contributed differently by biological and physio-chemical variables in the summer and winter periods, respectively.

Heavy metals cannot be biodegraded and they remain in the environment until being removed. Thus, the removal of heavy metals from contaminated water is of special concern for the protection of human and aquatic lives. Studies on polymer inclusion membranes (PIMs) started more than 50 years ago and have shown outstanding separation performance of metal ions. The potential and capabilities of PIMs have made it more favorable than ion exchange and liquid-liquid extraction process. To achieve efficient transport of metal ions, different types of extractant with compatible base polymer have been successfully used along with suitable targeted metal ions. However, selectivity of metal ion is only limited to one type of metal ion based on the extractant used in PIMs. The present review describes the current literature on heavy metal removal using PIMs for the past 3 years. The compatibility of extractant with base polymer and plasticizer is discussed. Most of PIM studies used cellulose triacetate (CTA) and polyvinyl chloride (PVC) as the base polymer, and only a few studies have used other base polymers. These new base polymers have shown better PIMs in terms of stability and separation performance compared to the CTA- and PVC-based PIMs. Moreover, a new invention of dual PIM separation system has allowed simultaneous separation of multiple metal ions. Such improvement in PIM technology can speed up commercialization process and make it viable for large scale and industrial use especially in hydrometallurgy and wastewater treatment.

Environmental contamination by mercury is a concern in marine food webs, and especially for large fish. We examined methylmercury (MeHg) levels in blood, muscle and liver of 35 individual Atlantic sturgeon (Acipenser oxyrhynchus), a commercially harvested, anadromous fish eastern Canada. Females had higher blood and liver MeHg levels than males, and in some tissues there was a suggestion of higher mercury in longer fish. Collectively, sturgeon MeHg levels were far below Canadian and international guidelines for safe consumption of fish meat.

Marine renewable energy (MRE) developments often coincide with sites frequented by small cetaceans. To understand habitat use and assess potential impact from development, echolocation clicks were recorded with acoustic click loggers (C-PODs) in Swansea Bay, Wales (UK). General Additive Models (GAMs) were applied to assess the effects of covariates including month, hour, tidal range and temperature. Analysis of inter-click intervals allowed the identification of potential foraging events as well as patterns of presence and absence. Data revealed year-round presence of porpoise, with distinct seasonal and diel patterns. Occasional acoustic encounters of dolphins were also recorded. This study provides further evidence of the need for assessing temporal trends in cetacean presence and habitat use in areas considered for development. These findings could assist MRE companies to monitor and mitigate against disturbance from construction, operation and decommissioning activities by avoiding times when porpoise presence and foraging activity is highest in the area.

Sediment trap samples from the shelf edge area (400-450m water depth), 58km northeast of the failed Macondo well, were collected before, during and after the Deepwater Horizon oil spill. Detailed chemical analyses of particulates revealed that fluxes of spill-derived TPH (2356μg/m2/day), total PAH (5.4μg/m2/day), and hopane (0.89μg/m2/day) settling to the seafloor directly beneath the surface-plume were 19- to 44-times higher during the active spill than pre- and post-spill background values. The oil was variably biodegraded, evaporated and photo-oxidized indicating that it derived from the sinking of surface oil. The hopane-based oil flux that we calculate (10bbl/km2) indicates that at least 76,000bbl of Macondo oil that reached the ocean surface subsequently sank over an area of approximately 7600km2. We explore how this flux of sunken surface oil contributed to the total volume of oil deposited on the seafloor following the Deepwater Horizon incident.

In aquatic environments, Cd contamination is a great concern because this non-essential metal presents risks both for wildlife and human health. Data about the concentration and transfer of Cd in Patagonian and Antarctic aquatic food webs are crucial for assessing the impacts of this element in pristine ecosystems. Consequently, the concentration of Cd was measured in thirty-two species collected in the 2014 austral summer from two locations of the Western Patagonia and two locations of the Antarctic Peninsula. The main objective of this work was to assess the relationship between Cd concentration and trophic level determined by δ15N. In the studied trophic positions, Cd showed a positive relationship between concentration and trophic level, which suggests biomagnification of this element in macroinvertebrates. However, there was a significant dilution when higher trophic organisms were considered.

Seabird colonies drastically transform the sites that they inhabit. Although the influence of seabirds on nutrient cycling has been investigated in numerous studies, the effects on trace elements has scarcely been considered. In this study, we determined the total contents of 9 trace elements in biomaterials (excrement, pellets, feathers and eggs) and soils in relation to the presence the Yellow-legged gull Larus michahellis. The concentrations of Zn, Cu and As were particularly high in the pellets and excrement. The total contents of the trace elements were significantly higher in the soils in the sub-colonies in which Yellow-legged gulls predominate than in soil from the control zone (with no gulls). The difference was even higher for the most reactive geochemical fractions. We observed that the oxidizable fraction was the most relevant fraction for almost all trace elements, indicating the importance of organic matter in trace element retention in sandy soils.