Time filter

Source Type

Vilagarcía de Arousa, Spain

Bernardez P.,CSIC - Institute of Marine Research | Bernardez P.,University of Vigo | Varela M.,Spanish Institute of Oceanography | Pazos Y.,Intecmar | And 2 more authors.
Journal of Plankton Research | Year: 2010

Seasonal variability of diatom abundances was measured in the water column, sediment traps and in the underlying sediment from the Pontevedra ría. Seasonal variations of the diatom species in the water column were indicative of ocean influence, river influx and water column stratification. Additionally, analysis of diatom distribution and other biosiliceous components was studied in 27 surface sediment samples. The marine planktonic assemblage in the surface sediments is located in the outer area of the ría. It is mainly composed by Chaetoceros resting spores (R.S.) together with Thalassionema nitzschioides, Leptocylindrus danicus R.S. and Paralia sulcata. Higher abundances of freshwater assemblages are limited to the inner ría, as well as crysophycean cysts and phytoliths, where the Lérez River has its strongest influence. The benthic group is also restricted to the innermost and shallow areas where shallow water depths allow for growth. Factor analysis distinguished between estuarine-freshwater and ocean-dominated upwelling areas in the Pontevedra ría. A mixed area where both processes take place was also discriminated. A good agreement between the biocoenotic and the thanatocoenotic diatom community was found. Despite the fact that the low preservation of some species obscures the interpretation of the sedimentary record of biogenic silica flux and accumulation, the results are useful in the reconstruction of hydrodynamics and production in the marine paleo-records in the ría and estuarine domains. This is even though the low preservation of some species results in difficulties interpreting the sedimentary record. Biological response, production patterns and diatom succession related with ecological preferences in this ría can also be applied to other rías and temperate coastal environments. © The Author 2010. Published by Oxford University Press. All rights reserved.

Garibo D.,IRTA - Institute of Agricultural-Alimentary Research and Technology | Damaso E.,IRTA - Institute of Agricultural-Alimentary Research and Technology | Eixarch H.,IRTA - Institute of Agricultural-Alimentary Research and Technology | de la Iglesia P.,IRTA - Institute of Agricultural-Alimentary Research and Technology | And 4 more authors.
Harmful Algae | Year: 2012

The applicability of the protein phosphatase inhibition assay (PPIA) to the determination of okadaic acid (OA) and its acyl derivatives in shellfish samples has been investigated, using a recombinant PP2A and a commercial one. Mediterranean mussel, wedge clam, Pacific oyster and flat oyster have been chosen as model species. Shellfish matrix loading limits for the PPIA have been established, according to the shellfish species and the enzyme source. A synergistic inhibitory effect has been observed in the presence of OA and shellfish matrix, which has been overcome by the application of a correction factor (0.48). Finally, Mediterranean mussel samples obtained from Ría de Arousa during a DSP closure associated to Dinophysis acuminata, determined as positive by the mouse bioassay, have been analysed with the PPIAs. The OA equivalent contents provided by the PPIAs correlate satisfactorily with those obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS). © 2012 Elsevier B.V.

Barton E.D.,CSIC - Institute of Marine Research | Largier J.L.,University of California at Davis | Torres R.,Plymouth Marine Laboratory | Sheridan M.,University of California at Davis | And 5 more authors.
Progress in Oceanography | Year: 2015

Semi-enclosed bays in upwelling regions are exposed to forcing related to winds, currents and buoyancy over the shelf. The influence of this external forcing is moderated by factors such as connectivity to the open ocean, shelter by surrounding topography, dimensions of the bay, and freshwater outflows. Such bays, preferred locations for ports, mariculture, marine industry, recreational activities and coastal settlement, present a range of characteristics, understanding of which is necessary to their rational management. Observations in such a semi-enclosed bay, the Ria de Vigo in Spain, are used to characterize the influence of upwelling and downwelling pulses on its circulation. In this location, near the northern limit of the Iberian upwelling system, upwelling events dominate during a short summer season and downwelling events the rest of the year. The ria response to the external forcing is central to nutrient supply and resultant plankton productivity that supports its high level of cultured mussel production. Intensive field studies in September 2006 and June 2007 captured a downwelling event and an upwelling event, respectively. Data from eight current profiler moorings and boat-based MiniBat/ADCP surveys provided an unprecedented quasi-synoptic view of the distribution of water masses and circulation patterns in any ria. In the outer ria, circulation was dominated by the introduction of wind-driven alongshore flow from the external continental shelf through the ria entrances and its interaction with the topography. In the middle ria, circulation was primarily related to the upwelling/downwelling cycle, with a cool, salty and dense lower layer penetrating to the inner ria during upwelling over the shelf. A warmer, lower salinity and less dense surface layer of coastal waters flowed inward during downwelling. Without external forcing, the inner ria responded primarily to tides and buoyancy changes related to land runoff. Under both upwelling and downwelling conditions, the flushing of the ria involved shelf responses to wind pulses. Their persistence for a few days was sufficient to allow waters from the continental shelf to penetrate the innermost ria. Longer term observations supported by numerical modeling are required to confirm the generality of such flushing events in the ria and determine their typical frequency, while comparative studies should explore how these scenarios fit into the range of conditions experienced in other semi-enclosed bays. © 2015 Elsevier Ltd.

Huhn F.,University of Santiago de Compostela | von Kameke A.,University of Santiago de Compostela | Allen-Perkins S.,TRAGSATEC | Montero P.,Intecmar | And 2 more authors.
Continental Shelf Research | Year: 2012

Horizontal Lagrangian surface transport is studied in the Ria de Vigo, an estuary in NW Spain with tidal and wind-driven dynamics. Surface drifters and the surface flow from a high-resolution 3-D hydrodynamic model are compared to each other. In particular, our analysis is based on a classical comparison of real and artificial trajectories and on Lagrangian Coherent Structures (LCS) defined as ridges in spatial fields of the Finite-Time Lyapunov Exponent (FTLE). The trajectories of the drifters are in good agreement with the prediction of the model in two out of four cases. Further, FTLE ridges computed from the model velocity fields are found to mark transport barriers for the drifters. The results indicate that the model is able to represent the general circulation in the estuary. Main patterns in the Lagrangian surface transport in the model are shown for two typical meteorological situations, north wind and south wind. They can be interpreted as an imprint of a 3-dimensional circulation pattern in the Ria de Vigo and reveal in detail the separation of the time-dependent in- and outflow at the surface of the estuary. © 2012 Elsevier Ltd.

Sampedro N.,CSIC - Institute of Marine Sciences | Franco J.M.,CSIC - Institute of Marine Research | Franco J.M.,Spanish Institute of Oceanography | Zapata M.,CSIC - Institute of Marine Research | And 8 more authors.
Harmful Algae | Year: 2013

The toxicity of Alexandrium andersonii Balech is unclear and its intraspecific variability has yet to be studied. To address these gaps in our knowledge, in the present work five strains of A. andersonii from four different localities were characterized. The results showed that despite genetic homogeneity in the 5.8-ITS (internal transcribed spacer) and large subunit (LSU) regions and similar growth rates, strains originating from different locations varied with respect to cell size, the ratios of certain pigments, and their growth patterns. Cultures of the strains grown at 20. °C were analyzed for toxicity using four different methodologies. The two officially established methods, mouse bioassay and high-performance liquid chromatography with fluorescence detection (HPLC-FLD) and post-column reaction analysis of PSP toxins, failed to show the toxicity of any strain. Strains grown at 14. °C were also negative for PSP toxins by HPLC-FLD. However, strains grown at 20. °C exhibited both a response characteristic of the presence of toxin-inhibiting voltage-gated sodium channels, as demonstrated in a neuroblastoma neuro-2a cell-based assay, as well as hemolytic activity in a sheep red blood cell assay. © 2013 Elsevier B.V.

Discover hidden collaborations