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Simple Summary: Many Vibrio species can be pathogens for aquatic macroalgae (e.g., Saccharina), animals (e.g., fish and shellfish) and even humans. Studies on the diversity and ecological distribution of Vibrio spp. will contribute to the conservation of aquatic aquaculture and have extremely important research value in terms of economic developments. Therefore, in this study, the distribution patterns of total and culturable Vibrio spp. in seawater along Ría de Vigo were investigated by cultivable methods, qPCR and high-throughput sequencing. The results of this study can provide a reference for management and pathogen prevention in aquaculture ecosystems in the context of global climate change. The genus Vibrio is genetically and ecologically diverse, resulting in severe economic losses in aquacultural macroalgae and animals. Studies on vibrios will contribute to the conservation of aquatic aquaculture in Ría de Vigo (Spain), which is famous for its shellfish farming activity. However, limited research focused on the diversity and distribution of Vibrio spp. in Ría de Vigo has been reported. Here, a slight increase in the abundance of Vibrio spp. was recorded from inshore to the open sea by quantitative PCR (qPCR). Vibrios were more abundant in the free-living (FL) than in the particle-associated (PA) fraction, showing that FL might be their preferential lifestyle. Photobacterium piscicola, Vibrio japonicus and Vibrio harveyi, which are serious pathogens for fish and invertebrates in mariculture, were found to be the dominant species across all samples by high-throughput sequencing and analyses and were mainly affected by stochastic processes. More colony-forming units and species of vibrios were recorded at 16 °C (18 species) than at 28 °C (6 species), and five isolates (5.05% of the total isolates) showed low 16S rRNA gene similarity (<98.65%) to the known strains. The results indicate that culture conditions closer to the in situ temperature may help to isolate more Vibrio species. Our findings may contribute to local aquatic aquaculture research, providing background information and novel insights for management and pathogen prevention in aquaculture, and more studies should focus on Ría de Vigo to acquire novel or pathogenic microbes in the future. [ABSTRACT FROM AUTHOR]

Increasing nutrient inputs driven by global environmental pressures may lead to changes in prokaryotic plankton biomass and community composition in coastal environments. Nutrient addition experiments (inorganic, organic, and mixed) were performed at the continental shelf outside the Ría de Vigo, in spring, summer and autumn 2014, and the results contrasted with those from similar previous experiments carried out inside the ría in 2013. The mixed nutrient additions caused the greatest changes in community composition, mostly consisting of blooms of Vibrionales. Inorganic nutrients yielded increased proportions of Oceanospirillales and Alteromonadales. Euclidean distances among samples were used to estimate compositional resistance to disturbances derived from nutrient additions. Changes in prokaryotic biomass were used as an indicator of biomass resistance. Generally, prokaryotic communities were more resistant to inorganic than organic nutrient additions. Communities sampled inside the ría, presumably exposed to greater perturbations, showed milder variability in the non-amended control than those from outside the ría. By contrast, shelf communities, with higher ambient organic matter concentrations, were more resistant to organic and mixed nutrient additions than those from the ría. Our data suggest that the perturbation history is related to the resistance of microbial communities to changes in nutrient inputs into the coastal ocean. [ABSTRACT FROM AUTHOR]

The genus Vibrio is genetically and ecologically diverse, resulting in severe economic losses in aquacultural macroalgae and animals. Studies on vibrios will contribute to the conservation of aquatic aquaculture in Ría de Vigo (Spain), which is famous for its shellfish farming activity. However, limited research focused on the diversity and distribution of Vibrio spp. in Ría de Vigo has been reported. Here, a slight increase in the abundance of Vibrio spp. was recorded from inshore to the open sea by quantitative PCR (qPCR). Vibrios were more abundant in the free-living (FL) than in the particle-associated (PA) fraction, showing that FL might be their preferential lifestyle. Photobacterium piscicola, Vibrio japonicus and Vibrio harveyi, which are serious pathogens for fish and invertebrates in mariculture, were found to be the dominant species across all samples by high-throughput sequencing and analyses and were mainly affected by stochastic processes. More colony-forming units and species of vibrios were recorded at 16 °C (18 species) than at 28 °C (6 species), and five isolates (5.05% of the total isolates) showed low 16S rRNA gene similarity (Vibrio species. Our findings may contribute to local aquatic aquaculture research, providing background information and novel insights for management and pathogen prevention in aquaculture, and more studies should focus on Ría de Vigo to acquire novel or pathogenic microbes in the future.

Because of the difficulties in tracking a water mass over time and conducting synoptic surveys over large spatial scales, measurements of biological variables in the ocean are often restricted to isolated Eulerian observations. Here a proof-of-concept of a pseudo-Lagrangian transformation was applied to a time series of chlorophyll-a profiles acquired at a single fixed station to diagnose the shape of a phytoplankton patch, and its physical-biological rates of transformation. During August 2013, a 27-hr time series of observations of horizontal currents, hydrographic properties, turbulent mixing and chlorophyll-a was acquired at a central station of the Ría de Vigo (NW Iberian Peninsula). A chlorophyll-a patch, tilted upward toward the inner part of the Ría, was observed moving back and forth past the sampling station. Its shape and position during the sampling period were modulated by the semi-diurnal (M2) tidal currents and the vertically sheared upwelling circulation. The pseudo-Lagrangian transformation allowed estimation of chlorophyll-a net rates of change. These rates were positive between 12 and 14 m depth, and negative elsewhere, with a mean value of −0.001 ± 0.449 days−1 within the patch maximum. After accounting for the effects of diffusion and sinking, the mean net biological production rate in the upper 15 m (0.53 ± 0.25 days−1) was comparable with in vitro estimates of the balance between phytoplankton growth and mortality obtained from dilution experiments carried out under similar conditions (0.2 ± 0.7 days−1). This pseudo-Lagrangian transformation is complementary to traditional analyses for the quantification of ecological processes and biogeochemical budgets.

Galician Rias are fluvial valleys that were flooded during the last marine transgression in the Atlantic margin. The study of fossil dunes in the Cies Islands, a small archipelago in the mouth of the one of the rias (Ria de Vigo), allowed us to reconstruct the coastal evolution from the end of the Late Pleistocene to the present day. During this period, sea-level was 100 metres below the present one and the shoreline located about 5–10 kilometres away. About 15,000 years ago, sea-level rise began, radically modifying the coastline. This started with a gradual advance of large dune fields on both sides of the valley. The aeolian accretion continued until the Late Holocene, finishing when the sea reached its present level. [ABSTRACT FROM AUTHOR]

On 24 June 2024, we detected foil that tightly adhered to an intertidal wall in Vigo harbor (Spain) during low tide. It covered multiple barnacles, potentially threatening their survival. We present photos of this novel debris-animal interaction and discuss possible effects that such cover could have on barnacles. [Display omitted] • First documented case of anthropogenic foil sealing filter-feeders. • Feeding, breathing and reproduction of the barnacles appear impaired. • Foil likely derived from wet wipe pollution. [ABSTRACT FROM AUTHOR]

Data from an acoustic Doppler current profiler (ADCP), a wave‐gauge, a met‐ocean buoy and model results provide new insights into the wave regime in a partially sheltered upwelling‐driven bay, the Ría de Vigo (NW Iberia), and the adjacent continental shelf from June 2013 to August 2014. Swell on the NW‐Iberian shelf comes mainly from NW directions, while wind sea comes from the NW under upwelling conditions, and from the SW under downwelling conditions. As the ria is protected from the NW and exposed to the SW, swell is almost always attenuated when entering the bay, and wave height inside the ria depends mostly on shelf wind sea variability. During the upwelling season, swell and wind sea barely enter the ria and wave heights inside the ria are small (0.21 m). During the downwelling season, shelf wind sea directly enters the ria, contributing more to the total wave height which achieves its maximum values (0.46 m). There is a cumulative action of wave and currents (wave current coupling, WCC) that is stronger during the downwelling season. The WCC entails an increase in the seabed energy which could reinforce bottom remineralization. The inter‐annual variability (2009–2016) of winter wave height and WCC in the ria is associated with the combined role played by the North Atlantic Oscillation (NAO) and West Europe Pressure Anomaly (WEPA) indices. The highest waves and strongest WCC occur during the coincidence of negative NAO and positive WEPA phases and can have potentially relevant repercussions on the ecosystem services of the ria. Plain Language Summary: This manuscript focuses on the wave regime inside a semi‐enclosed and upwelling‐driven bay (Ría de Vigo, NW Iberian Peninsula), its relationship with wind‐driven currents and the seasonal and inter‐annual variability of both. Our results show that although the wave regime on the shelf is dominated by swell, inside the ria wind sea is the major contributor to wave height variability. As wind sea is generated by the same local winds that control the wind‐driven currents (coastal upwelling/downwelling), there is a wave‐current coupling that has relevant effects on the ecosystem services of the ria. At inter‐annual scales, the winter variability of the wave regime and the wave current coupling are related to the variability of main climatic modes of the Eastern North Atlantic. Key Points: Orientation of the ria and local orography allow shelf wind sea to control ria wave regime during downwelling, but not during upwellingDuring downwelling, wave‐driven currents and wind‐driven currents are strongly coupled in the ria, but not during upwellingInter‐annual winter variability of waves, currents and their coupling are strongly correlated with the interplay of West Europe Pressure Anomaly and North Atlantic Oscillation indices [ABSTRACT FROM AUTHOR]

Previous studies focused on understanding the role of physical drivers on phytoplankton bloom formation mainly used indirect estimates of turbulent mixing. Here we use weekly observations of microstructure turbulence, dissolved inorganic nutrients, chlorophyll a concentration and primary production carried out in the Ría de Vigo (NW Iberian upwelling system) between March 2017 and May 2018 to investigate the relationship between turbulent mixing and phytoplankton growth at different temporal scales. In order to interpret our results, we used the theoretical framework described by the Critical Turbulent Hypothesis (CTH). According to this conceptual model if turbulence is low enough, the depth of the layer where mixing is active can be shallower than the mixed-layer depth, and phytoplankton may receive enough light to bloom. Our results showed that the coupling between turbulent mixing and phytoplankton growth in this system occurs at seasonal, but also at shorter time scales. In agreement with the CTH, higher phytoplankton growth rates were observed when mixing was low during spring-summer transitional and upwelling periods, whereas low values were described during periods of high mixing (fall-winter transitional and downwelling). However, low mixing conditions were not enough to ensure phytoplankton growth, as low phytoplankton growth was also found under these circumstances. Wavelet spectral analysis revealed that turbulent mixing and phytoplankton growth were also related at shorter time scales. The higher coherence between both variables was found in spring-summer at the ~16–30 d period and in fall-winter at the ~16–90 d period. These results suggest that mixing could act as a control factor on phytoplankton growth over the seasonal cycle, and could be also involved in the formation of occasional short-lived phytoplankton blooms.

Because of the difficulties in tracking a water mass over time and conducting synoptic surveys over large spatial scales, measurements of biological variables in the ocean are often restricted to isolated Eulerian observations. Here a proof‐of‐concept of a pseudo‐Lagrangian transformation was applied to a time series of chlorophyll‐a profiles acquired at a single fixed station to diagnose the shape of a phytoplankton patch, and its physical‐biological rates of transformation. During August 2013, a 27‐hr time series of observations of horizontal currents, hydrographic properties, turbulent mixing and chlorophyll‐a was acquired at a central station of the Ría de Vigo (NW Iberian Peninsula). A chlorophyll‐a patch, tilted upward toward the inner part of the Ría, was observed moving back and forth past the sampling station. Its shape and position during the sampling period were modulated by the semi‐diurnal (M2) tidal currents and the vertically sheared upwelling circulation. The pseudo‐Lagrangian transformation allowed estimation of chlorophyll‐a net rates of change. These rates were positive between 12 and 14 m depth, and negative elsewhere, with a mean value of −0.001 ± 0.449 days−1 within the patch maximum. After accounting for the effects of diffusion and sinking, the mean net biological production rate in the upper 15 m (0.53 ± 0.25 days−1) was comparable with in vitro estimates of the balance between phytoplankton growth and mortality obtained from dilution experiments carried out under similar conditions (0.2 ± 0.7 days−1). This pseudo‐Lagrangian transformation is complementary to traditional analyses for the quantification of ecological processes and biogeochemical budgets. Plain Language Summary: Oceanography distinguishes two ways to make observations: Eulerian and Lagrangian. Eulerian approaches measure properties at fixed locations in space as a function of time as water flows past the instrument. In contrast, Lagrangian approaches quantify temporal changes in fluid parcels while following the flow. Isolated Eulerian observations are the most common approach to investigate biological properties. However, temporal variations in Eulerian observations result from combinations of physical and biological processes whose effects are often difficult to separate. We applied a pseudo‐Lagrangian methodology to reconstruct the spatial structure of a phytoplankton (microscopic algae) patch observed at a single station in a coastal embayment. Because the flow was dominated by tidal currents, some water parcels were sampled multiple times, allowing to compute the rate of change of properties in the phytoplankton patch. Biological production, or the rate of change due to biological processes, was comparable with traditional estimates from in vitro experiments performed in the region under similar hydrographic conditions. Our findings show that the pseudo‐Lagrangian transformation is a useful complement to data obtained from traditional analyses for the quantification of ecological processes and biogeochemical budgets. Key Points: A pseudo‐Lagrangian transformation was applied to diagnose the shape of a phytoplankton patchThe pseudo‐Lagrangian transformation allowed estimation of Chl‐a fluorescence net rates of changeNet biological production was comparable with in vitro estimates from dilution experiments under similar hydrographic conditions [ABSTRACT FROM AUTHOR]

The Gómez-Muñoz model was developed to aid the management of small-scale or artisanal fisheries and is based on interview data from fishermen and other personnel directly related to the fishery. The non-targeted and targeted Loligo vulgaris fishery in the Ría de Vigo and the Aldán Cove is explored. Eighty-one interviews were carried out. This survey yielded 38 valid interviews, which were used to estimate the parameters of the model for the period 2011-2015. Comparison between official landings and catches estimated by this model showed discrepancies varying between 41.8% and 98.4%, depending on the fish markets considered. An 82.2% decrease of the squid catches over the period 2011-2015 was recorded. The reasons for that drop as well as the sensitivity and accuracy of the model are discussed.

Subterranean estuaries (STEs), where continental groundwaters and saltwaters meet, are zones of intense biogeochemical reactivity. As such, STEs significantly modify groundwater-borne nutrient fluxes to the coastal zone. Thus, evaluating their reactive role is crucial to anticipate impacts of submarine groundwater discharge (SGD) over coastal ecosystems. Here, we studied the nitrogen biogeochemistry of two STEs with contrasting wave-exposure and redox conditions in Panxón and Ladeira beaches (Ría de Vigo, NW Iberian Peninsula). Seasonal surveys were performed at the permanently saturated zone of both beaches during low tide in February, May, July, and October 2019. Sediment was sampled and porewater samples collected using push-pull piezometers. Salinity, 222Rn and 226Ra activities were used to trace water circulation inside each beach. Porewater nitrate, ammonium, nitrite and dissolved oxygen were used to evaluate the role of these STEs as reactive sinks or sources of inorganic nitrogen. Our results showed a marked seasonal variability of water circulation inside both beaches, with strong salinity gradients in February and May and weakened circulation in July and October. The presence of a gravel layer in Panxón beach completely altered the typical structure of STEs by increasing porewater transport and mixing through the beach interior. As a result, Panxón beach profiles were highly enriched in nitrate and oxygen. Conversely, suboxic, and anoxic conditions were prevalent in Ladeira beach during the study period, with ammonium being the prevailing inorganic nitrogen form. High nitrate concentrations occurred associated to the tidal circulation cell during February and May, being the only effective mechanism of sediment oxygenation in Ladeira beach. Although nitrate reduction and production were observed in both STEs, comparison with averaged conservative mixing porewater profiles showed that Ladeira beach acted as a net nitrogen sink whereas Panxón beach acted as a net nitrogen source. The presence of a gravel layer oxygenates the interior of Panxón beach, thus limiting nitrate reduction and promoting the amplification of groundwater-borne nitrogen fluxes to the coast.

Wildfire ash can have an impact on coastal prokaryotic plankton. To understand the extent to which community composition and abundance of coastal prokaryotes are affected by ash, two ash addition experiments were performed. Ash from a massive wildfire that took place in the Ría de Vigo watershed in October 2017 was added to natural surface water samples collected in the middle sector of the ría during the summer of 2019 and winter of 2020, and incubated for 72 h, under natural water temperature and irradiance conditions. Plankton responses were assessed through chlorophyll a and bacterial abundance measurements. Prokaryotic DNA was analyzed using 16S rRNA gene partial sequencing. In summer, when nutrient concentrations were low in the ría, the addition of ash led to an increase in phytoplankton and bacterial abundance, increasing the proportions of Alteromonadales, Flavobacteriales, and the potentially pathogenic Vibrio , among other taxa. After the winter runoff events, nutrient concentrations in the Ría de Vigo were high, and only minor changes in bacterial abundance were detected. Our findings suggest that the compounds associated with wildfire ash can alter the composition of bacterioplanktonic communities, which is relevant information for the management of coastal ecosystems in fire-prone areas. [Display omitted] • Wildfire ash had an impact on bacterioplankton abundance and phytoplankton biomass. • The greatest changes in chlorophyll a and bacterial abundance happened in summer, under low-nutrient conditions. • Exposure to wildfire ash aqueous extracts changed the composition of the bacterioplankton community. • Alteromonadales, Flavobacteriales, and Vibrio increased their relative abundances after exposure to ash. [ABSTRACT FROM AUTHOR]

The use of marine bivalves in metal pollution monitoring is undoubtedly one of the best tools to evaluate metal pollution in coastal areas worldwide. However, since bivalves integrate metal pollution from both the dissolved and the particulate phases, it cannot be assured that metal bioaccumulation in their tissues will predict the risk posed by metals to sensitive organisms such as invertebrate larvae or microalgae, which are known to be mainly affected by the free metal ion fraction. This study aims to test the usefulness of mussel gills-the primary exchange surfaces with dissolved metals-in reflecting dissolved metal bioavailability in the field. For that, we analyzed metal concentrations in environmental samples (whole soft tissues of mussels, mussel gills, sediment, and particulate and dissolved fractions in the water column) collected from 7 sampling sites during a multi-year investigative monitoring survey in the Ría de Vigo. The results showed a different pattern of Cu and Zn accumulation in gills compared to whole soft tissues, and these differences are attributable to the faster response of gills to changes in dissolved metal concentrations and to the regulation of essential metals at the whole body level. In the case of Pb, by contrast, concentrations in gills were very similar to those in the whole body. The use of mussel gills in metal pollution biomonitoring is a promising tool for the detection of changes in bioavailable metals in the environment, especially for essential metals such as Cu and Zn. [ABSTRACT FROM AUTHOR]

Over the past decades, as a consequence of human activity, there was an increase in nutrient inputs to the ocean and they are expected to enhance even more in the future. Coastal areas, accounting for a significant proportion of marine primary productivity, are the most vulnerable zones to anthropogenic impacts. The response of phytoplankton communities to an increase in organic and inorganic nutrients levels from natural allochthonous sources was assessed in microcosm experiments conducted in a coastal system affected by intermittent upwelling events (Ría de Vigo, NW Iberia). Three nutrient addition experiments were performed in spring, summer and autumn, when surface water was supplemented with 5 and 10% of atmospheric and riverine matter. Pico-, nano- and microphytoplankton abundances, chlorophyll a concentration (Chl a ) and primary production rates (PP) were measured and compared with those in the control seawater sample (without additions) after 48 h of incubation. Simultaneous experiments with controlled additions of inorganic and organic nutrients were also performed in order to describe the limiting nutrient for phytoplankton growth at each experiment. The composition of the matter inputs and the structure of the phytoplankton communities determined the type of response observed. Phytoplankton responses varied among seasons, being positively correlated with dissolved inorganic nitrogen (DIN) concentrations. As expected, the phytoplankton responses to external nutrient inputs were stronger under low nutrient levels (summer) than when phytoplankton was already growing in nutrient replete conditions (spring). Null and negative responses to the natural inputs were observed in autumn, which suggests that the oceanic phytoplankton advected to this coastal system during downwelling events could be occasionally inhibited by these nutrient inputs. In a future global change scenario, characterized by enhanced nutrient inputs from riverine and atmospheric origin, the response of phytoplankton communities will strongly depend on the concentration and chemical composition of these inputs and on the structure of phytoplankton communities able to respond to them. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and carbon (C) isotopic analyses in seagrasses have been established as effective environmental tracers to assess the anthropogenic influence on seagrass meadows. The aim of this study was to determine the spatial patterns and seasonal variability in the C and N stable isotopic composition of sediments, leaves and epiphytes at a Zostera noltei meadow in an intertidal complex located at the Ría de Vigo (NW Iberian Peninsula) and to explore the mechanisms underlying such variability. Measurements of carbon and nitrogen stable isotopes, morphological features of Z. noltei and the C:N mass ratios were undertaken monthly during an annual seasonal cycle. N recycling between the seagrass and the sediment under its canopy influenced the spatial and seasonal nitrogen isotopic variability in the Z. noltei meadow. The relative contribution of nitrogen stable isotopes both in Z. noltei and the sediments under its canopy showed significant seasonal differences. The seasonal variability observed in carbon and nitrogen stable isotopes and C:N mass ratios of Z. noltei was mainly explained by the physiological mechanisms of carbon and nitrogen uptake and the differential nutrient demand of the plant depending on the growth stage. [ABSTRACT FROM AUTHOR]

The high sedimentation rates and high organic matter contents in the sediments of the Ría de Vigo (NW Spain) promote the development of anoxic conditions, determining the dynamics of elements like Fe and conditioning his speciation and reactivity. Four gravity cores were retrieved in anoxic sediments of the Ría de Vigo in November 2012. In order to understand the behavior of Fe in these complex environments different fractions of reactive iron were analyzed. The decrease in highly reactive iron and sulfide contents with depth showed the relationship between the iron and sulfur cycle in the middle and outer zones of the ría. In the inner zone, the apparition of shallow methane gas may cause the slower decrease of the highly reactive iron contents. In zones without methane, sediment layers enriched in iron −with a reactivity higher than in other sediment samples− were observed. An increase was observed in the dithionite and total reactive iron contents from the inner to the outer zone of the ría, according to the gas depth. Furthermore, a decrease in Fe (III)-bearing minerals contents with depth was observed in the outer and middle zones, but not in the innermost area where the gas is shallow. The high organic matter and sulfide contents, mainly in the inner zone of the ría, indicate that the most of the Fe (II) is FeS. Moreover, the high contents of total reactive iron and pH values (6.86–7.98) could contribute the formation of stable minerals like pyrite along the Ría de Vigo. [ABSTRACT FROM AUTHOR]

The intertidal and subtidal soft-bottoms of the inner area of the Ria de Vigo (NW Spain) were sampled in November and December 1999, and spatial distribution of crustacean species was examined. Environmental variables from water and sediment were measured at each sampling site. Amphipods and myocopids were the numerically dominant orders (49.9 and 26.9% dominance), amphipods accounting for more than 54% of identified taxa. The highest crustacean densities occurred with 55-41 species and 5953.6-4346.4 ind. m–2 in external areas, where the diversity index reached the maximum values. Multivariate techniques revealed that distribution of crustaceans in the inlet was highly dependent on depth. Ordination analysis determined three major assemblages: Intertidal bottoms colonized by seagrasses and subjected to strong variations of salinity were dominated by the amphipod Melita palmata, harpacticoids and the isopod Idotea baltica (Group A). The amphipod Corophium cf. runcicorne and the cumacean Iphinoe tenella predominated in the muddy bottoms of central areas (Group B). These species were also present in the deep muddy bottoms of the mouth of the inlet, with high carbonate and gravel contents, and with the myocopids and the amphipod Microdeutopus cf. armatus displaying maximum dominances (Group C).

River runoff off northwest Iberia generates a low-density buoyant structure with a strong influence on shelf and coastal circulation. This study estimates the runoff to the shelf of the ten largest rivers in the region based on the furthest downstream gauge records available, and also takes into account the basin area downstream from the station (22% of the basin area for the entire study region). Monthly statistics were computed to obtain mean values for each river to cover the recurrent lack of runoff data in the region. In order to reconstruct gaps in the time series on a daily scale, a method based on the observed discharge of a nearby river basin was used. In addition, the influence of runoff on the shelf was analyzed using monthly CTD data sampled during a 12-year period in the Ría de Vigo and the adjacent shelf. The CTD series shows the existence of a buoyant structure with maximum growth during winter and with large variability of its thermal anomaly. The salinity anomaly correlated significantly with mean winter monthly values of the North Atlantic Oscillation (NAO) index. This atmospheric index integrates both the influence of precipitation —and therefore runoff— and the predominant winds during winter that contribute to the accumulation of fresh water over the shelf.

The potential power output expected from the installation of a tidal farm near the mesotidal Ria de Vigo (NW Spain) is assessed using two different tidal stream energy converters (TEC). For this, the results of a previous resource assessment based on a 28-day long hydrodynamic simulation are used. From this data we identify the areas susceptible of hosting the farms, select the optimal location for them, and assess the total available and extractable energy for each turbine type. Finally, using a simple farm design based on standard inter-turbine separation, we estimate the expected power supplied by the farm. Irrespective of the site, the total available tidal power in the areas susceptible of hosting the farms is around 150 MW; at the optimal location, the hourly extractable power is about 22.5 MW, of which only between 10% and 15% can be harnessed by the designed farms, powering between 4411 and 6638 homes. A local analysis of the most energetic subregions within these sites increases this ratio up to 30%. Nevertheless, the power output is sufficient to fulfil the needs of between 1660 and 2213 households, depending on the chosen site and the selected TEC. [ABSTRACT FROM AUTHOR]

The goal of this paper is to find out whether suspended mussel culture affects the vertical fluxes of biogenic particles in the Ría de Vigo on a seasonal scale. With this aim, vertical fluxes of particulate organic carbon (POC) and the magnitude and composition of vertical export of phytoplankton carbon (Cphyto) collected in sediment traps were examined by comparing data obtained inside a mussel farming area (RaS) with those found at a reference station (ReS) not affected by mussels. Our results indicate that mussel farming has a strong impact on sedimentation fluxes under the rafts, not only increasing POC flux but also altering the magnitude and composition of Cphyto fluxes. Average POC flux at RaS (2564 ± 1936 mg m day) was four times higher than at ReS (731 ± 276 mg m day), and much of this increase was due to biodeposit fluxes (Cbiodep) which accounted for large proportion of POC flux (35-60 %). Indeed, because of this high Cbiodep flux, only a small proportion of the POC flux was due to Cphyto flux (3-12 %). At the same time, we observed an increased sedimentation of phytoplankton cells at RaS that could be explained by a combination of mechanisms: less energetic hydrodynamic conditions under mussel rafts, ballast effect by sinking mussel feces, and diatom aggregates. Moreover, mussel farming also altered the quality of the Cphyto flux by removing part of the predatory pressure of zooplankton and thus matching diatom composition in water column and sediment traps. [ABSTRACT FROM AUTHOR]

Two short-range (46 MHz) Coastal Ocean Dynamics Application Radar (CODAR) SeaSonde HF were operating in the Ría de Vigo during one year between September 2012 and August 2013 to permit observations of the surface circulation in the outer region of the Ría de Vigo (NW Spain). An analysis of low-pass current and vorticity conducted over one year revealed two opposite vorticity structures in the HF radar coverage area. Simultaneously, wind stress and its curl, calculated at two meteorological stations (Cíes and Borneira) in the HF radar coverage area, were assessed to establish the main mechanisms promoting the formation of these two opposite vorticity structures. Researchers selected three periods of 58, 41.5, and 77 days within the study year in which radar and wind data were simultaneously recorded at two stations. Examining HF radar vorticity at specific grid points representing both vorticity structures reveals a greater correlation between HF radar vorticity and the y-component of wind stress at the outermost meteorological station (Cíes) for all periods (R=0.52–0.80).Only one period (1 Sep–28 Oct 2012) displayed a correlation between the vorticity and the curl wind stress calculated at these two meteorological stations (R=0.50–0.62). Once wind forcing has been reported as the main factor responsible for generating these dipolar vorticity structures at subtidal frequencies, these structures can be shown to develop in two patterns: (1) counter-clockwise and clockwise relative vorticity in the northern and southern outer ría respectively, mainly developing during the transition from upwelling to downwelling, and with a lifetime normally dependent to the duration of the subsequent downwelling/relaxation conditions; and (2) clockwise and counter-clockwise vorticity in the northern and southern outer ría respectively, mainly generated during moderate or intense upwelling events. The life span of these vorticity structures ranges from 2 to 8 days. The largest range between positive and negative vorticity, or the most extreme vorticity, is observed/recorded during downwelling events. This is the first time these double vorticity structures have been observed at low frequencies in the outer Ría de Vigo. Their existence is key to understanding the mechanisms of transport between the Ría de Vigo and the shelf, and they could help explain the retention of plankton or pollutants inside some regions of the ría. [ABSTRACT FROM AUTHOR]

The Ría of Vigo (Galicia, Spain) is an estuarine system modulated by fluctuating alongshore southward and northward winds (associated with downwelling and upwelling events respectively). This lead to a very productive ecosystem that supports an important artisanal fishery of Octopus vulgaris. Additionally, the Islas Cíes, an important spawning site for O. vulgaris, connect the Ría de Vigo with the ocean through two mouths (north and south) that determinate the inflow and outflow (depending on upwelling-downwelling events). Several researches have attempt to understand the ecology of O. vulgaris early stages (i.e. paralarvae) in the Ría, but there is still little knowledge about the vertical behavior of Octopus paralarvae, which may be modulated by this oceanographic variability. This work studies the distribution of the paralarvae at both mouths and inside the Ría in different upwelling and downwelling events. For this, we undertook 3 oceanographic cruises at night in early autumn in 2013: One cruise to characterize distributions during an upwelling event, another during a downwelling event and a 24 hours cruise during a strong upwelling event to determinate day-night variation. Sampling strategy consisted on two transects intersecting the inflow and outflow at both mouths, and one transect following the water fluxes moving along the Ría. Sampling was performed with a multinet trawl gear from the bottom to the surface every 5 meters. Results show different patterns according to variation of oceanographic conditions: - Downwelling situation: Southerly winds push superficial waters (0-15m) into the Ría through the southern mouth and are washed out through the northern mouth. Bottom waters leave the Ría through the southern mouth. The cruise was undertaken after a strong downwelling event during previous days, and showed that the highest abundance of paralarvae was at the southern mouth concentrated below superficial waters (10-25m), rising to the surface (0-5 m) at the inner part of the Ría. - Upwelling situation: superficial waters (0-20m) enter through the northern mouth of the Ría and are washed through the southern mouth. This water movement promotes the entrance of cold, bottom upwelled water through the southern mouth of the Ría. Under this scenario, Octopus paralarvae are concentrated at the surface (10-0m), thus leaving the Ría. This difference is bigger after strong upwelling during the previous days. Abundances inside the Ría are the highest, maybe because it acts as a temporal retention area, or because cold upwelled waters might stimulate hatching inside the Ría. Day/night changes under strong upwelling conditions: paralarvae abundance in both mouths was quite similar, except that during the day they were in sub-surficial waters (10-5 m), while at night paralarvae were mainly found close to the surface (0-5 m). This vertical distribution during the day is remarkable because paralarvae may select offward surface waters.

A three-dimensional, non-linear, baroclinic model is described and tested for the first time to study the residual circulation and the thermohaline distribution of the Ría de Vigo (NW Spain) at short time scales and under different wind stress regimes. Two markedly different realistic scenarios were chosen: northerly upwelling-favourable winds and southerly downwelling-favourable winds. The numerical experiments carried out indicate that the hydrodynamic regime of the Ría de Vigo is mostly a consequence of wind events. As could be expected, moderately strong North winds reinforce the normal (positive) Ría circulation, while winds blowing from the South, when sufficiently strong, reverse the typical circulation pattern and reduce the characteristic outgoing velocities and the flushing time inside the Ría. The temperature and salinity fields generated by the model in both situations were compared with observations and found to be in qualitatively good agreement, supporting the 3D velocity field distribution.

Two phytoplankton succession events (September-October 1993 and March 1994) in the Ría de Vigo were studied in relation to their hydrodynamic context. By means of a circulation box model we calculated horizontal and vertical residual fluxes as well as budgets of phytoplankton associated with them. This allowed us to assess the importance of the two factors involved in the selection processes: one hydrodynamic (dependent upon physical dispersion) and one biogeochemical (involving all other processes such as growth, mortality and grazing). The first period was characterised by a downwelling event which produced a reversal of the estuarine circulation pattern (horizontal velocity = 4 km d-1 and downward velocities up to 9 m d-1). This provided suitable conditions for the blooming of Gymnodinium catenatum favoured by its capacity to swim, while the diatom community almost disappeared. The second period corresponded to an upwelling Æ relaxation sequence. During upwelling (horizontal velocity = 6 km d-1; upward velocities up to 12 m d-1), Thalassiosira spp. was dominant. It is suggested that the less energetic conditions associated with the relaxation event (horizontal velocity=1 km d-1; upward velocities < 1 m d-1) favoured the selection of Chatoceros spp. due to its lower sinking rate.

The Ría de Vigo is a semi-enclosed bay with high primary productivity due to the influence of coastal upwelling-downwelling dynamics. The area is heavily populated and affected by numerous human activities, which lead to sediment modification. Epibenthic megafauna from the non-estuarine zones of this bay has been studied in order to describe its spatial distribution, testing possible differences between inner and outer areas. With that purpose, 75 sites have been sampled by means of a towing dredge. Megafauna was identified to the lowest taxonomic level possible, and each taxon counted and weighted. 113 different taxa were identified and a high spatial heterogeneity was observed in terms of abundance, biomass, taxa richness, diversity and evenness. Suspension-feeding molluscs dominated the innermost part of the studied area, and were substituted by echinoderms towards the external zones; this spatial pattern was also reflected in the results of multivariate analyses. These shifts in taxonomic and trophic guild composition of the assemblages have been tentatively related to differences in pollution levels and primary productivity along the main axis of the bay. [ABSTRACT FROM AUTHOR]

Coastal upwelling is one of the best studied oceanographic phenomena because of its effects on primary production. The western coast of the Iberian Peninsula has high biological diversity, mainly due to this primary production. In this study, the response of salinity and temperature to the occurrence of upwelling was analysed at the Ria de Vigo- and Ria de Aveiro-ocean boundary over the course of a year. Both systems were influenced by similar external forcing, but the response of thermohaline properties differed. Salinity and temperature were dependent on external forcing throughout the water column at Ria de Aveiro, whereas near-bed measurements revealed the presence of upwelled water at Ria de Vigo. Eastern North Atlantic Central Water was observed during spring-summer (summer) at the southern (northern) mouth of Ria de Vigo, but it was not observed at Ria de Aveiro. This difference may be due to the shallowness and narrowness of the Ria de Aveiro mouth, which can limit the entrance of ocean water. The trends found are unlikely to be unique, suggesting that geomorphologic characteristics of system-ocean boundaries determine how physical processes occurring in adjacent coastal areas impact estuarine properties. The western coast of the Iberian Peninsula has high biological diversity, mainly due to coastal upwelling. The response of thermohaline properties to upwelling events was analysed at two estuarine systems over a year. Results suggest that geomorphological characteristics of system-ocean boundaries determine how physical processes occurring in adjacent coastal areas affect estuarine properties. [ABSTRACT FROM AUTHOR]