Southwest Nova Scotia (SWNS) is Canada's most productive lobster (Homarus americanus) fishing region. Abandoned, lost, and discarded fishing gear (ALDFG) is widespread. This baseline study provides the first preliminary assessment of environmental and economic impacts of ALDFG on the commercial lobster industry in SWNS. Fishers conducted 60 retrieval trips, searched ~1523 km² of the seafloor and removed 7064 kg of ALDFG (comprising 66% lobster traps and 22% dragger cable). Results showed that lost traps continued to capture target and non-target species until gear degraded. A total of 15 different species were released from retrieved ALDFG, including 239 lobsters (67% were market-sized) and seven groundfish (including five species-at-risk). The present findings, combined with information on regional fishing effort and market prices, estimate that commercial losses from ALDFG can exceed $175,000 CAD annually. This baseline assessment provides useful data for government and commercial fishing stakeholders to improve ALDFG management.

The study was conducted to improve knowledge and provide guidance on reducing uncertainty with impact predictions when drilling near sensitive environments. Near/Far-field hindcast modelling of cuttings/drilling fluid (mud) discharges from a floating platform was conducted, based on measured discharge amounts and durations and validated by ROV-based plume and seabed sampling. The high volume, concentration, and discharge rate water-based drilling mud discharges (mud pit dumps) were identified as the most significant dispersal risk, but longer-range movement was limited by the generation of jet-like plumes on release, which rapidly delivered muds to the seabed (80 m). Effects to the sparse benthic filter feeder communities close to the wells were observed, but no effects were seen on the epibenthic or demersal fish assemblages across the nearby mesophotic reef. For future drilling near sensitive environments, the study emphasized the need to better characterise drilling fluid discharges (volumes/discharge rates) to reduce uncertainty in modelling outputs.

Floating marine debris (FMD) were abundantly reported in the Northern Chilean Patagonia in 2009 where sea-based activities (mussel and salmon aquaculture) are responsible for most of them. Identifying the sources of FMD is important to take the necessary actions to diminish their abundance. In 2019 eleven transects were opportunistically conducted to evaluate the abundance, spatial distribution and composition of FMD in the same area, and to compare them with the previous study using the same methodology. FMD identified were classified into the same six categories from the previous study, however “Others” category were now the dominant one indicating that new pollutants have been increasing during the last decade. Inside the “others” category, plastics buoy and other floating devices, that normally are used by the salmon aquaculture, were the main items. Similarly than the previous study, styrofoam and domestic plastics were also the other most abundant items. In general, also, an increase in abundance compared with the previous study was found. The highest abundances were similarly found in the “Golfo de Corcovado” zone ranging from 50 to 230 items km⁻². Our results, as well as the previous study, confirm that sea-based activities are still responsible for the FMD found in the Northern Patagonia. To avoid the origin of this contamination it is urgent to implement public policies that effectively reduce FMD, and hold the aquaculture industries responsible.

The abalone aquaculture industry in South Korea has grown rapidly since the 2000s. In this study, we investigated the sedimentary pollution at four major abalone farms responsible for ~60% of all South Korean abalone produced. We also surveyed the current statuses of cage facilities, abalone mass mortality, and current velocities within and outside farm cages. The concentrations of total organic carbon in the study area were 7.92 ± 2.09 mg g⁻¹, indicating a mild level of sedimentary pollution. We observed higher mortality rates in rectangular-shaped shelter cages than in triangular shelters. With increases in the number and size of abalone farming facilities, current velocities inside the cages declined by an average of 45% relative to those outside the cages, leading to poor habitat conditions for farmed abalone. Our results provide insights into the current status of the benthic environments and major causes of mass mortality in the abalone farms of South Korea.

We investigated spatiotemporal distributions of dissolved inorganic nutrients and organic carbon (DOC) and nitrogen (DON) in coastal waters and land-based fish farm wastewater to determine effects of wastewater on seawater of Jeju Island, Korea. The nutrient concentrations in seawater were lower than in wastewater with negative correlations against salinity, indicating a terrestrial source. Wastewater-derived DOC and DON were transported offshore while wastewater-derived inorganic nutrients were effectively removed, likely via biological production, and this was closely linked to decline in N:P ratios. The correlations between DOC, DON, and colored dissolved organic matter suggest that organic matters likely originate from the fish farm wastewater. Quantitatively, the estimated wastewater-derived DOC flux was equivalent to that through submarine groundwater, which is a significant water source on the island. Our results will be able to trace contaminant sources and support assessments of seawater quality for appropriate regulation of fish farm wastewater discharge into coastal zones.

Ocean acidification generates a decrease in calcium carbonate availability essential for biomineralization in organisms such as mollusks. This effect was evaluated on Panopea globosa exposing for 7 days umbonate veliger larvae to two pH treatments: experimental (pH 7.5) and control (pH 8.0). Exposure to pH 7.5 affected growth, reducing larval shell length from 5.15–13.34% compared to the control group. This size reduction was confirmed with electron microscopy, also showing shell damage. The physiological response showed an increase in oxygen consumption in larvae exposed to low pH with a maximum difference of 1.57 nmol O₂ h⁻¹ larvae⁻¹ at day 7. The gene expression analyses reported high expression values for nicotinamide adenine dinucleotide (NADH) dehydrogenase and Perlucin in larvae at pH 7.5, suggesting a higher energetic cost in this larval group to maintain homeostasis. In conclusion, this study showed that acidification affected development of P. globosa umbonate veliger larvae.

A big challenge of the 21st century is to cope with the huge amounts of plastic waste on Earth. Especially the oceans are heavily polluted with plastics. To counteract this issue, biological (enzymatic) plastic decomposition is increasingly gaining attention. Recently it was shown that polyethylene terephthalate (PET) can be degraded in a saltwater-based environment using bacterial PETase produced by a marine diatom. At moderate temperatures, plastic biodegradation is slow and requires sensitive methods for detection, at least at initial stages. However, conventional methods for verifying the plastic degradation are either complex, expensive, time-consuming or they interfere with the degradation process. Here, we adapt lensless digital holographic microscopy (LDHM) as a new application for efficiently monitoring enzymatic degradation of a PET glycol copolymer (PETG). LDHM is a cost-effective, compact and sensitive optical method. We demonstrate enzymatic PETG degradation over a time course of 43 days employing numerical analysis of LDHM images.

Marine debris, particularly plastic debris is a ubiquitous global pervasive problem. The international community recognizes that a reduction in plastic debris density is central to sustainable ocean use based on reduction performance metrics. Although many national databases already exist or are being developed, an internationally accepted index of plastic debris density does not currently exist. Standardized methods for monitoring marine debris can help inform policy decisions to reduce sources marine debris and support mitigation effectiveness.Vietnam recently committed to addressing marine debris nationally and internationally and developed ambitious targets to manage and reduce ocean plastic debris, yet Vietnam does not currently have a national marine debris monitoring database. This study identified international best practices and standards; developed a marine plastic database for accurate, efficient information gathering, management, and reporting; and developed a centralized database platform for future marine plastic debris management in Vietnam that can be adapted for other jurisdictions.

The occurrence, ecological risk, and source of heavy metals in the Liaohe River Protected Area from the watershed of the Bohai Sea were investigated. The maximum concentrations of Cu, Zn, Ni, Cd, Cr, Pb, and As in water were 8.50, 25.22, 3.80, 0.14, 1.76, 8.52, and 3.19 μg/L, respectively. The maximum concentrations of Cu, Zn, Ni, Cd, Cr, Pb, and As in sediment were 27.0, 109, 33.2, 0.56, 318, 43.7, and 29.3 mg/kg, respectively. The percentages of soil samples with observed concentrations above background values were 31.25%, 31.25%, 25%, 28.13%, 56.25%, 34.38%, and 37.5% for Cu, Cr, Zn, Ni, Cd, Pb, and As, respectively. Igₑₒ suggested that sediments were polluted with Cd, Pb, As, Cr, and Zn, whereas soils were contaminated with all seven metals. Potential ecological risk index values exhibited that sites L25 and L12 were classified as moderately polluted in sediment and soil, respectively.

In recent years, dense Alexandrium ostenfeldii blooms have been reported in different coastal areas. In this study, we report for the first time the occurrence of A. ostenfeldii blooms associated with the detection of paralytic shellfish toxins (PSTs) in the Peruvian scallop (Argopecten purpuratus) from Paracas Bay. Alexandrium ostenfeldii blooms occurred at the end of summer and early fall, after the increase of riverine input and under stratified conditions following a decrease in wind velocity. The highest abundances occurred during warm sea surface temperatures (18–27 °C). High PST concentrations that exceed the maximum permissible level (800 μg STX eq. kg⁻¹) occurred even under low A. ostenfeldii abundances (20 × 10³ cells l⁻¹). Our results contribute to a better understanding of the dynamics of A. ostenfeldii in coastal systems influenced by riverine inputs and upwelling and can be used to improve monitoring programs and allow the implementation of mitigation measures along the Peruvian coast.