Temperature and salinity vertical profiles (CTD) data in the Ría de Vigo and adjacent shelf collected in the Radiales program, 1987-2020.

The Galician rías and their adjacent continental shelf form part of the northern boundary of the Canary Current upwelling system (CanCUS), one of the world's major eastern boundary upwelling ecosystems (EBUEs). During summer, prevailing northerly winds export surface water offshore, allowing deeper, cooler, nutrient-rich water to rise, creating a fertilizing effect on coastal waters that support valuable fisheries and aquaculture economy. This data article describes a time series of hydrographic data collected on a biweekly to monthly frequency from August 1987 to September 2020 in the interior of the Ría de Vigo (one of the aforementioned Galician rías) and its adjacent shelf. This monitoring effort results in the longest sampling series in the area up to 2020, providing high value for understanding the connectivity processes between the coastal embayment and the adjacent shelf, changes in ocean climate, as well as ecosystem structure and functioning. Data were collected with vertical pressure, temperature and conductivity profilers, varying the profiler instrument over time (MARK III, SBE 9 Plus, SBE 19, SBE 25). Data were collected at four stations with depths ranging from 29 m to 148 m, although only two of these stations cover the full temporal range of the monitoring program. Due to the temporal extent of the sampling, the data have been processed with different techniques and by different technicians throughout the duration of the monitoring program. To ensure data consistency and increase data reusability, all data have been now reprocessed under the same criteria, quality-controlled, and unified in this dataset. The dataset in both MedAtlas SeaDataNet ASCII and CF-compliant netcdf formats are available via SEANOE repository at: https://www.seanoe.org/data/00828/94008/.

A nationwide monitoring of atmospheric microplastic deposition.

Plastic production continues to increase every year, yet it is widely acknowledged that a significant portion of this material ends up in ecosystems as microplastics (MPs). Among all the environmental compartments affected by MPs, the atmosphere remains the least well-known. Here, we conducted a one-year simultaneous monitoring of atmospheric MPs deposition in ten urban areas, each with different population sizes, economic activities, and climates. The objective was to assess the role of the atmosphere in the fate of MPs by conducting a nationwide quantification of atmospheric MP deposition. To achieve this, we deployed collectors in ten different urban areas across continental Spain and the Canary Islands. We implemented a systematic sampling methodology with rigorous quality control/quality assurance, along with particle-oriented identification and quantification of anthropogenic particle deposition, which included MPs and industrially processed natural fibres. Among the sampled MPs, polyester fibres were the most abundant, followed by acrylic polymers, polypropylene, and alkyd resins. Their equivalent sizes ranged from 22 µm to 398 µm, with a median value of 71 µm. The particle size distribution of MPs showed fewer large particles than expected from a three-dimensional fractal fragmentation pattern, which was attributed to the higher mobility of small particles, especially fibres. The atmospheric deposition rate of MPs ranged from 5.6 to 78.6 MPs m-2 day-1, with the higher values observed in densely populated areas such as Barcelona and Madrid. Additionally, we detected natural polymers, mostly cellulosic fibres with evidence of industrial processing, with a deposition rate ranging from 6.4 to 58.6 particles m-2 day-1. There was a positive correlation was found between the population of the study area and the median of atmospheric MP deposition, supporting the hypothesis that urban areas act as sources of atmospheric MPs. Our study presents a systematic methodology for monitoring atmospheric MP deposition.

Temperature and salinity trends in the northern limit of the Canary Current Upwelling System.

Thermohaline time series are crucial for detecting and quantifying abiotic changes in the marine environment, and even more so in the present global change scenario. This is particularly relevant for the Ría the Vigo and its adjacent shelf, a highly productive ecosystem at the northern limit of the Canary Current Upwelling System (CanCUS). This study analyses a 34-year time series (1987-2020) of Conductivity-Temperature-Depth (CTD) casts, the longest series available to date in the region. Long-term trends, shifts, and seasonal variability of temperature and salinity were assessed and investigated in relation to regional meteorological variability and basin-scale atmospheric teleconnection indices. Generalized Additive Models (GAM) allowed us to determine that monthly thermohaline variability can be largely explained by regional meteo-climatic variability, mainly upwelling index and river discharge. Trends and shifts in some teleconnection patterns, especially the East Atlantic (EA) pattern, may also be related to both the shift in salinity in 2013 and its long-term decrease below 50 m depth. Despite the current global warming context, no statistically significant trend was observed for either the upwelling index or temperature. The spatial analysis of sea surface temperature trends suggests that our study area has been responding to climate change differently from other surrounding near-shore areas, as the Finisterre Cape or the southern Bay of Biscay. Overall, this study highlights the importance of long-term observations to elucidate the impact of climate change in the northern limit of the CanCUS and encourages caution when extrapolating conclusions from ecosystem studies on a regional scale.

Top 10 marine litter items on the seafloor in European seas from 2012 to 2020.

We studied the ten most frequently encountered litter items from the seafloor in European seas to advance actions and inform future mitigation measures to reduce marine litter and the associated social, economic and environmental impacts it has on European seas and beyond. Data were collected during trawl surveys from 2012 to 2020 as part of national and regional marine litter monitoring programmes in the Greater North Sea (5652 trawls), Celtic Seas (3505), Bay of Biscay (651), and Baltic Sea (3688). A Bayesian approach is used to quantify the variation in the item rankings. Overall, plastic items predominate in the top positions in each area. Synthetic rope, plastic sheets, monofilament fishing line and plastic bags occupy four of the top five positions for each of the Greater North Sea, Celtic Seas and the Bay of Biscay. Items from fishing and rope (representing mainly other maritime activities) are strongly represented in the top ten lists from three of our four areas, with synthetic rope, fishing nets, and tangled and untangled monofilament fishing line listed in the top seven positions for the Greater North Sea, Celtic Seas and the Bay of Biscay. The top ten items in the Baltic Sea are of a different profile to the other regions, but the most commonly caught items are still predominantly plastic, with plastic sheets, other plastic items and plastic bags occupying three of the top four positions. The findings in this study highlight the need to address sea-based sources to try and eliminate litter from fishing and maritime activities. Measures such as improved port reception facilities, marking of fishing gear, promoting reporting of the loss of fishing gear and increasing public awareness should be introduced.

Occurrence and size distribution study of microplastics in household water from different cities in continental Spain and the Canary Islands.

The purpose of this study was to investigate the occurrence of microplastics (MPs) in drinking water in Spain by comparing tap water from different locations using common sampling and identification procedures. We sampled tap water from 24 points in 8 different locations from continental Spain and the Canary Islands by means of 25 µm opening size steel filters coupled to household connections. All particles were measured and spectroscopically characterized including not only MPs but also particles consisting of natural materials with evidence of industrial processing, such as dyed natural fibres, referred insofar as artificial particles (APs). The average concentration of MPs was 12.5 ± 4.9 MPs/m3 and that of anthropogenic particles 32.2 ± 12.5 APs/m3. The main synthetic polymers detected were polyamide, polyester, and polypropylene, with lower counts of other polymers including the biopolymer poly(lactic acid). Particle size and mass distributions were parameterized by means of power law distributions, which allowed performing estimations of the concentration of smaller particles provided the same scaling parameter of the power law applies. The calculated total mass concentration of the identified MPs was 45.5 ng/L. The observed size distribution of MPs allowed an estimation for the concentration of nanoplastics (< 1 µm) well below the ng/L range; higher concentrations are not consistent with scale invariant fractal fragmentation. Our findings showed that MPs in the drinking water sampled in this work do not represent a significant way of exposure to MPs and would probably pose a negligible risk for human health.

PAHs and trace metals in marine surficial sediments from the Porcupine Bank (NE Atlantic): A contribution to establishing background concentrations.

Little is known about pollutant concentrations in marine remote areas such as the Porcupine Bank in the NE Atlantic Ocean. Remote locations are much less studied than the more readily accessible coastal areas, nevertheless, are of great importance both to unveil how far human influence has reached and, are more challenging, to infer background concentrations (BCs) of naturally occurring and/or anthropogenic pollutants. Knowledge of contaminant background levels are critical for establishing remediation and management strategies; in addition, background assessment is heavily emphasised in legislative monitoring requirements. Obtaining suitable sampling locations to assess background concentrations can be challenging, as samples should match characteristics to the target area and not be impacted by historical or current inputs of the chemical substances of study. Anthropogenic impacts generally deem local-based sampling to be unsuitable to infer background pollution values. Sampling in remote areas such as the Porcupine Bank better fulfils low impact and pressure requirements making them more suitable for the derivation of background concentration estimates for organic compounds and metals. The total concentrations of polycyclic aromatic hydrocarbons (PAHs) and metal(loid)s in deep sea sediments were evaluated and both an environmental status and a set of concentration data were adequate to derive BCs concentrations is presented. Concentration data indicated, in comparison with previous published data, trace level presence of PAHs and metal(loids) in sediments from the Porcupine Bank. These values will provide a valuable tool to identify the natural presence of organic and inorganic compounds and be the basis to perform a sound environmental assessment.

Microplastic occurrence in deep-sea fish species Alepocephalus bairdii and Coryphaenoides rupestris from the Porcupine Bank (North Atlantic).

Microplastic occurrence in marine biota has been reported in a wide range of animals, from marine mammals and seabirds to invertebrates. Commercial and shallow-water fish have been the subject of numerous works on microplastic ingestion, given their importance in human diet and accessibility. However, little is known about microlitter occurrence in fish species inhabiting the dark ocean, in the bathyal zone and there is a high degree of uncertainty about microplastic distribution in offshore areas and the deep sea. In this study, bathydemersal species Alepocephalus bairdii and Coryphaenoides rupestris from the Porcupine Bank caught between 985 and 1037 m depth were inspected for microdebris. The stomach contents were digested by the alkaline method plus ethanol addition to avoid clogging. A filament of Polyethylene Terephthalate (PET) was found in the stomach of a specimen of A. bairdii, representing 4% of the total sampled specimens of this species (i.e. prevalence in n = 25). However, when considering potential microplastics, the prevalence increased to 28% in both, A. bairdii and C. rupestris. This work provides the first baseline study of microplastic items in fish from such depths in the Atlantic and suggests these species might be used as biomonitors in future research.

The seasonal cycle of micro and meso-plastics in surface waters in a coastal environment (Ría de Vigo, NW Spain).

Marine litter is an emerging environmental problem. In this study, micro and mesoplastics were determined for the first time in seawater in Ría de Vigo (Spain) identifying their concentration, annual cycle, size, shape and polymer composition. Besides, temporal variations at an annual scale were also established. The Ría de Vigo is well known for the important industry related to marine activities (fishing, mollusc culture, shipyards, and tourism). Three sampling stations were selected along the transverse axis of Ría and were monthly sampled for one year. Seawater samples were collected using a manta trawl and analyzed with ATR-FTIR, and Raman spectroscopy to determine plastic polymer type. The mesozooplankton community (0.2-20 mm) was also studied. The samples were collected with bongo nets in the same sampling stations as plastics. Manta trawl net (330 µm) was used to collect 32 samples (identifying 854 plastic particles; 677 microplastics and 177 mesoplastics). The mean concentration across all sites was 25.4 ± 13.4 items·km-2. The microplastics abundance was greater than that of mesoplastics (79%, and 21%, respectively). Around 30% of plastics analyzed were Polyethylene (PE), 19% were acrylates, 18% were Polypropylene (PP) and 10% were Polystyrene (PS). The main shapes of both micro and mesoplastics were fibers followed by paint sheets being black the main colour in both cases. The results showed high seasonal variability by micro and mesoplastics but similar spatial distribution. This seasonal heterogeneity can have effects on a future monitoring program. Furthermore, it was demonstrated that pollution by mesoplastics cannot be estimated through the microplastics abundances. Regarding the values of microplastics-zooplankton, they present a great negative correlation.

Micro and Nano-Plastics in the Environment: Research Priorities for the Near Future.

Plastic litter dispersed in the different environmental compartments represents one of the most concerning problems associated with human activities. Specifically, plastic particles in the micro and nano size scale are ubiquitous and represent a threat to human health and the environment. In the last few decades, a huge amount of research has been devoted to evaluate several aspects of micro/nano-plastic contamination: origin and emissions, presence in different compartments, environmental fate, effects on human health and the environment, transfer in the food web and the role of associated chemicals and microorganisms. Nevertheless, despite the bulk of information produced, several knowledge gaps still exist. The objective of this paper is to highlight the most important of these knowledge gaps and to provide suggestions for the main research needs required to describe and understand the most controversial points to better orient the research efforts for the near future. Some of the major issues that need further efforts to improve our knowledge on the exposure, effects and risk of micro/nano-plastics are: harmonization of sampling procedures; development of more accurate, less expensive and less time-consuming analytical methods; assessment of degradation patterns and environmental fate of fragments; evaluating the capabilities for bioaccumulation and transfer to the food web; and evaluating the fate and the impact of chemicals and microorganisms associated with micro/nano-plastics. The major gaps in all sectors of our knowledge, from exposure to potentially harmful effects, refer to small size microplastics and, particularly, to the occurrence, fate and effects of nanoplastics.

The role of cigarette butts as vectors of metals in the marine environment: Could it cause bioaccumulation in oysters?

Tobacco is a well-documented threat to human health. However, its environmental impact has only recently been considered. Metals can interact with cigarette butts (CBs) being transported in the marine environment and reaching organisms. To understand this mechanism, a series of metal(loid)s were analyzed in cigarette filters (virgin, artificially smoked, leached in seawater and aged in beach and harbour) as well as in artificially contaminated oyster tissues. Smoked filters showed higher levels of metals compared to the virgin ones showing enrichment factors up to 90, probably associated with tobacco metal content. Once the CBs are delivered to the environment, metals can be leached to seawater until reaching equilibrium, which may be dependent on initial metal levels in the water. Copper was the element with the highest percentage of desorption (91 ± 3%) while strontium showed the lowest percentage (40 ± 0%). CBs revealed a great capacity to accumulate metals from the environment when weathered in contaminated areas. A chemical impact derived from CBs contamination might exist as they serve as a carrier for metals in the marine environment. The release of metals from CBs or the ingestion of metal loaded CBs may pose a toxicological risk for marine organisms via accumulation in their tissues.

Phthalates, organotin compounds and per-polyfluoroalkyl substances in semiconfined areas of the Spanish coast: Occurrence, sources and risk assessment.

In this work two sensitive areas of the Spanish coast located in the Atlantic (Ria de Vigo) and Mediterranean (Mar Menor lagoon) have been studied regarding their contamination by phthalates, organotin compounds and per-polyfluoroalkyl substances (seawater and sediments) in two different campaigns (spring and autumn in 2015). PFAS and OTCs were detected in seawater and sediments at low concentrations (few ng L-1 or ng g-1), whereas PAEs were detected at levels two orders of magnitude higher, particularly in Mar Menor lagoon due to its semi-confined characteristics. However, PAEs and OTCs concentration in sediments were higher in Ría de Vigo than in Mar Menor lagoon as a consequence of the influence of the important urban nuclei and port in that area. The ecological risk assessment revealed that in both areas tributyltin, dibutyltin and diethylphthalate pose a significant risk in sediments, whereas in seawater tributyltin in both areas resulted in a high risk.

Modelling the distribution of microplastics released by wastewater treatment plants in Ria de Vigo (NW Iberian Peninsula).

The accumulation of plastic waste in estuaries is growing due to the increase in their use in daily life and their inadequate treatment on wastewater plants (WWTPs). Hydrodynamic and particle-tracking models were validated and used to improve the knowledge about the distribution and concentration of microplastics released by WWTPs in the Ria de Vigo. Results showed that the Vigo WWTP is the main driver of microplastics to the Ria de Vigo. Besides, 21% of the released microplastics reach the adjacent ocean, 24% remain anchored around the Cies Islands, and a negligible percentage reaches the upper estuary when the emission occurs under ebb on spring tide conditions. A negligible number of released microplastics is exported to the nearby ocean when the emission occurs under neap tide conditions. This research can provide a useful tool to support the identification of monitoring processes and debris removal.

Plackett Burman design for microplastics quantification in marine sediments.

Microplastics are gaining worldwide attention due to their omnipresence. The marine environment is one of the most affected systems; especially the sediment compartment. Microplastic separation from the sediment matrix is the first step to evaluate its abundance and availability. Nevertheless, a lack of consistency in extraction protocols is a fact. This paper describes the optimization of the microplastic extraction procedure from marine sediments. The Plackett-Burman saturated factorial design was used to identify the significant factors and to select optimum working conditions. With this purpose, the following variables were studied: the number of extractions; the amount of sediment; the settling time; the density separation solution volume; the agitation time and the suitability of using wet or freeze-dried sediment. The Plackett-Burman design has revealed that the most statistically significant variables were sediment mass and agitation time. The optimized method was applied for two marine sediments collected in the Mar Menor Lagoon.

From the coast to the shelf: Microplastics in Rías Baixas and Miño River shelf sediments (NW Spain).

Microplastics (<5 mm; MPs) are globally recognized as an issue of emerging concern in the marine environment. In this study, MPs were determined for the first time in sediments from Rías Baixas and Miño river shelf, to show the baseline contamination levels. The Rías is well known for its intense fishing and shellfish harvesting activities. The sampling stations were selected due to their different exposure to anthropogenic activities and/or pressures. Sediment samples were collected using a box corer dredge and analyzed with density separation and µF-TIR analysis to determine polymer type. The results showed MPs pollution in all stations. The mean concentration was 70.2 ± 74.2 particles/kg DW. The main MPs shape was fibers (88.8%) followed by fragments (5.80%). Regarding the polymers, the most abundant were PP (43%) and HDPE (29%). Once again, MPs are ubiquitous all along Rías and Miño river mouth as previously shown in different works.

Microplastic ingestion by pelagic and benthic fish and diet composition: A case study in the NW Iberian shelf.

We evaluated the incidence of microplastics in the digestive tract contents of four fish species: Engraulis encrasicolus, Sardina pilchardus, Callionymus lyra and Mullus surmuletus. Alkaline digestion (10% KOH) was used to degrade the organic matter. The percentage of fish with microplastics was 78% (88% fibres, 12% fragments). The main types of polymers identified by Raman spectroscopy were polyethylene and polypropylene. The diet of the four species was also studied and two feeding types were determined: plankton-feeders and benthic-feeders. The effect of a set of biological variables (Length, Fullness index, Fulton's condition factor and Feeding type) on the number and size of microplastics ingested was studied using Generalised Additive Models (GAMs). A significant increase in the number of microplastics with increasing length was observed. No significant effect of trophic variables (fullness index and feeding type) on the number and size of microplastics was found.

Microplastics in the Bay of Biscay: An overview.

Microplastics (MPs) are an environmental problem of growing concern, and several studies have defined the Bay of Biscay (BoB) as a marine litter accumulation area. To address the abundance of MPs in this region, a critical overview is presented compiling the research performed to date on the different water bodies, sediments and biota. The comparative assessment highlights high spatial and temporal variability in MP distribution. MPs appear in at least 50% of the samples in waters and sediments. Polypropylene, polyethylene, polyester and polystyrene are the most frequent polymers, with a significant predominance of fragments and fibres. The BoB can be considered a region with medium concentration of MPs. However, monitoring programmes are needed to compile data over time and thus evaluate the historical trends of MP pollution. The difficulty of comparing studies is highlighted, due to the use of different methodologies. Hence, the harmonisation of monitoring methods is urgently required.

Fibers spreading worldwide: Microplastics and other anthropogenic litter in an Arctic freshwater lake.

We investigated the presence of microplastics and other anthropogenic litter in the sediments adhered to rocks of an Arctic freshwater lake at Ny-Ålesund (Svalbard Archipelago, 78°N; 11°E). Most of the sampled microparticles were fibers (>90%). The identification of polymer types and additives was performed by combining three spectroscopic techniques, namely Raman Microscopy, Fourier-Transform Infrared microspectroscopy (µFTIR) and Synchrotron Radiation µFTIR (SR-FTIR). SR-FTIR confirmed the presence of poly(ethylene terephthalate) fibers, while RAMAN spectroscopy provided evidence of fibers containing industrial additives. Our results estimated an average concentration of 400 microparticles/m2 of rocks identified as anthropogenic litter, which included an estimation of 90 microplastics/m2 identified as polyester fibers; the rest are mostly natural fibers with evidence of anthropogenic origin. Taken together, the results proved the occurrence of anthropogenic pollutants in remote polar areas. Their probable origin is the long range atmospheric transport.

Uptake of Inorganic and Organic Nitrogen Sources by Dinophysis acuminata and D. acuta.

Dinoflagellate species of Dinophysis are obligate mixotrophs that require light, nutrients, and prey for sustained growth. Information about their nitrogenous nutrient preferences and their uptake kinetics are scarce. This study aimed to determine the preferred nitrogen sources in cultures of D. acuminata and D. acuta strains from the Galician Rías Baixas (NW Spain) and to compare their uptake kinetics. Well-fed versus starved cultures of D. acuminata and D. acuta were supplied with N15 labeled inorganic (nitrate, ammonium) and organic (urea) nutrients. Both species showed a preference for ammonium and urea whereas uptake of nitrate was negligible. Uptake rates by well-fed cells of D. acuminata and D. acuta were 200% and 50% higher, respectively, than by starved cells. Uptake of urea by D. acuminata was significantly higher than that of ammonium in both nutritional conditions. In contrast, similar uptake rates of both compounds were observed in D. acuta. The apparent inability of Dinophysis to take up nitrate suggests the existence of incomplete nitrate-reducing and assimilatory pathways, in line with the paucity of nitrate transporter homologs in the D. acuminata reference transcriptome. Results derived from this study will contribute to understand Harmful Algal Blooms succession and differences in the spatio-temporal distribution of the two Dinophysis species when they co-occur in stratified scenarios.

Plastic debris accumulation in the seabed derived from coastal fish farming.

In this study, we assessed plastic accumulation in marine sediments due to finfish aquaculture using floating net-pens. We studied plastic concentrations around three fish farms located at the Mediterranean coastline of Spain. The macroplastic categories and abundances were determined by video monitoring, detecting the majority of elements (78%), including ropes, nets and fibres, a basket trap and a cable tie, close to the facilities, which were not exclusively linked to fish farming but also to fishing activities. Concentrations of microplastics (<5 mm) ranged from 0 to 213 particles/kg dry weight sediment with higher values in sites directly under the influence of the fish farms. Most particles (27.8%) were within the size fraction from 1.1 to 2.0 mm and fibre was the most common shape with 62.2%. The Infrared spectroscopy analysis showed that PE and PP were the predominant types of polymers analysed. In addition, changes in the enthalpy of melting (ΔHm (J/g)) and the degree of crystallinity indicate degradation of the microplastics analysed. This study shows that, in the studied fish farms, levels of microplastic pollution can be one order of magnitude lower compared to other areas suffering other anthropogenic pressures from the same or similar regions. Nevertheless, more research effort is needed to get concluding results.