Contributions of Pacific Islands countries to marine plastic debris are disproportionate to the effects on people's connections to the ocean. Plastic waste management initiatives face challenges in containing waste and consequently plastics plague coastal environments. The Seabin, a floating trash skimmer, presents a novel and replicable approach to collecting and cataloguing marine plastics. The objectives of the study were to conduct an audit of marine plastic debris within the breakwaters of the University of the South Pacific, Marine Campus at Laucala Bay while simultaneously gauging the effectiveness of the Seabin and providing recommendations to enhance its utility. Inorganic debris was comprised entirely of plastics while the majority of debris collected was organic. This study provides the first assessment of floating marine plastic debris in an inshore environment of a Pacific Island country. Plastic debris assessments have the potential to inform policy and pivot management efforts to mitigate plastic waste pollution.

Estimated natural background levels (NBLs) are needed to assess groundwater chemical status according to the EU Groundwater Directive. They are commonly derived for different substances by applying statistical methodologies. Due to the complexity of the sea water intrusion process, some of those methods do not always provide appropriate assessment of chloride NBLs. This paper analyzes the applicability of different NBL estimation methods in five EU coastal aquifers with significant differences in available datasets and hydrogeological settings. A sensitivity analysis of results to different constraints was performed to remove samples with anthropogenic impacts. A novel statistical approach combining different methods to identify the range of chloride NBLs is proposed. In all pilots the estimated NBLs were below 85 mg/L and fitted well with previous studies and expert judgment, except Campina del Faro aquifer (the maximum being 167.5 mg/L). Although this approach is more time consuming, it provides a more robust solution.

The control of macroalgal bloom development is central for protecting estuarine ecosystems. The identification of the nutrients limiting the development of macroalgal blooms, and their most likely sources is crucial for management strategies. Three Irish estuaries (Argideen, Clonakilty and Tolka) affected by green tides were monitored from June 2016 to August 2017. During each sampling occasion, biomass abundances, tissue N and P contents, and δ¹⁵N were determined for tubular and laminar morphologies of Ulva. All estuaries showed maximum biomass during summer and minimum during winter. Tissue nutrient contents revealed P rather than N limitation. The δ¹⁵N during the peak bloom indicated agriculture as the most likely source of nitrogen in the Argideen and Clonakilty, and urban wastewaters in the Tolka. No differences in the δ¹⁵N, and the tissue nutrients content were observed between morphologies. The period between May and July is most suitable for bioassessment of green tides.

Marine litter can be found along coasts, continental shelves and slopes, down into the abyss. The absence of light, low temperatures and low energy regimes characterising the deeper habitats ensure the persistence of litter over time. Therefore, manmade items within the deep sea will likely accumulate to increasing quantities. Here we report the litter abundance encountered at the Pacific abyssal nodule fields from the Peru Basin at 4150 m depth. An average density of 2.67 litter items/ha was observed. Litter composed of plastic was the most abundant followed by metal and glass. At least 58 % of the items observed could be linked to the research expeditions conducted in the area and appeared to be mostly accidental disposals from ships. The data gathered was used to address temporal trends in litter abundance as well as the impact of human on-site presence and return cruises in the context of future deep-sea mining efforts.

Microplastics are a relevant environmental concern in marine ecosystems due to their ubiquity. However, knowledge on their dispersion patterns within the ocean basin and the interaction with biota are scarce and mostly limited to surface waters. This study investigated microplastic contamination in two species of deep-sea cephalopods from the southwestern Atlantic with different ecological behaviour: the vampire squid (Vampyroteuthis infernalis) and the midwater squid (Abralia veranyi). Microplastic contaminated most of the evaluated specimens. V. infernalis showed higher levels of contamination (9.58 ± 8.25 particles individual⁻¹; p < 0.05) than A. veranyi (2.37 ± 2.13 part. ind.⁻¹), likely due to the feeding strategy of V. infernalis as a faecal pellets feeder. The size of extracted microplastics was inversely proportional to the depth of foraging. The microplastics were highly heterogeneous in composition (shape, colour and polymer type). Our results provide information regarding microplastic interaction with deep-sea organisms and evidence of the biological influence in the microplastic sinking mechanism.

Fuzzy Cognitive Mapping (FCM) is a participatory modelling tool used to explore complex systems by facilitating interdisciplinary cooperation and integrating a variety of knowledge systems. Here FCM was used to explore marine microfiber pollution. Through individual interviews with representatives from the research, industry, water and environmental sectors, five stakeholder FCMs were developed and used to produce an aggregated community FCM in a stakeholder workshop. Stakeholder FCMs and the revised community FCM were used to compute how the modelled system reacted to changes under two scenarios developed during the stakeholder workshop; (i) Green Shift and (ii) increased textile consumption and production. Significant differences were observed in scenario results from the stakeholder-based models and the community-based model. For societal challenges characterized by unknowns around the problem and potential solutions, inclusion of a variety of knowledge systems through FCM and deliberation processes contribute to a more holistic picture of the system and its uncertainties.

Time series of temperature, salinity and nutrients in the Strait of Gibraltar (SoG) were researched to analyze which factors explain the invasive success of Rugulopteryx okamurare, which has colonized wide coastal areas at the Spanish and Moroccan coasts since 2016. Temperature and salinity were higher in the SoG compared to its native habitat, implying that the alga is active during the whole seasonal cycle and grows optimally at the high salinities occurring in the SoG. Nitrate removal experiments indicate that the alga is able to linearly increase its N uptake rates following boost in nitrate concentration. Furthermore, R. okamurae N content ranged from 1.4% to 4.5% suggesting that this species has high N storage capacity potentially usable when the external N concentration decreases. These physiological characteristics would explain sharp growth of the alga in the SoG where high N concentrations are registered occasionally.

Nanoparticles (NP) are potentially reprotoxic, which may compromise the success of populations. However, the reprotoxicity of NP is still scarcely addressed in marine fish. Therefore, we evaluated the impacts of environmentally relevant and supra environmental concentrations of titanium dioxide (TiO₂: 10 to 10,000 μg·L⁻¹) and silver NP (Ag: 0.25 to 250 μg·L⁻¹) on the sperm of gilthead seabream (Sparus aurata). We performed short-term direct exposures (ex vivo) and evaluated sperm motility, head morphometry, mitochondrial function, antioxidant responses and DNA integrity. No alteration in sperm motility (except for supra environmental Ag NP concentration), head morphometry, mitochondrial function, and DNA integrity occurred. However, depletion of all antioxidants occurred after exposure to TiO₂ NP, whereas SOD decreased after exposure to Ag NP (lowest and intermediate concentration). Considering our results, the decrease in antioxidants did not indicate vulnerability towards oxidative stress. TiO₂ NP and Ag NP induced low spermiotoxicity, without proven relevant ecological impacts.

We aimed to describe how debris originated from coastal cities and fisheries circulates and accumulates along the Argentine continental shelf and its potential interaction with southern giant petrels (SGP, Macronectes giganteus). We used tracking data of 31 SGPs (adults and juveniles) from Patagonian colonies. Lagrangian simulations of particles were released from coastal cities and fisheries. Oceanographic features together with plastic input generated a corridor of debris through the Argentine shelf with areas of high debris accumulation, exposing SGP to plastic consumption. During chick provisioning trips 93.9% of petrel's locations overlapped with areas of plastic accumulation. Although early developmental stages were more exposed to particles from cities, the exposure of petrels (all classes) to debris from fisheries was 10% higher than from cities. Measures to reduce debris from fisheries, would reduce plastic ingestion by giant petrels. Proper management of open sky dumpsters would reduce plastic consumption by chicks and juveniles.

Anthropogenic debris is used as nesting material by many seabirds and may result in negative impacts. We assessed the frequency of occurrence of debris (>5 mm) in Kelp Gull (Larus dominicanus) nests at six locations along 2400 km of the Argentine coast, at different distances from urban centres, and in nests of other seven seabird species nesting syntopically. Frequencies in Kelp Gull nests were in general relatively low, ranging between 3.3 and 37.5%, and differed significantly among colonies. No relationship was found between frequency and distance to urban centres. Debris were recorded with frequencies of less than 19.2% in nests of Olrog's Gulls (L. atlanticus), Dolphin Gulls (L. scoresbii), Imperial Cormorants (Leucocarbo atriceps) and Magellanic Penguins (Spheniscus magellanicus), but not in nests of Neotropical Cormorants (Nannopterum brasilianus), Rock Shags (Leucocarbo magellanicus) and Southern Skuas (Catharacta antarctica). This information obtained along a wide coastal sector provides a baseline for future monitoring.