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- Phytoplankton distribution and physical processes off NW Iberia during two consecutive upwelling seasonsPublication . Oliveira, P. B.; Amorim, F. N.; Dubert, J.; Nolasco, R.; Moita, TeresaThis work presents the results of two oceanographic surveys conducted off NW Iberia during successive summer upwelling seasons, aiming at the identification of the physical processes underlying the phytoplankton distribution in the area. Mooring (ADCP and thermistors) and ship-based CTD-F observations corroborate previous results that wind-driven upwelling circulation, (sub)mesoscale eddies and the stratification induced by the Western Iberia Buoyant Plume (WIBP) are the main processes affecting the chlorophyll distribution, but also provide new insights on key oceanographic structures governing the shelf circulation and phytoplankton structuring, namely (i) the link between frontal activity along the shelf break south of similar to 41 degrees N, the flow bifurcation at that latitude and the establishment of a cyclonic area with low frontal activity over the mid-shelf; (ii) the measurement of a previously unreported, remarkably persistent (> 1 month), near bottom poleward flow at the 30 m isobath, interpreted as the response to the alongshore pressure gradient driven by the stronger upwelling intensity north of 41 degrees N; (iii) the impact of low salinity buoyant plumes expressed on the shallowing of the Ekman layer, with the consequent frictional (Ekman) currents intensity increase, their low chlorophyll content contrary to previous winter/spring observations, and the lack of a direct relationship between plume salinities and river runoff; and (iv) the strong coupling between the chlorophyll distribution and the small-scale (O(1 - 10)km) oceanographic features providing further evidence that the phytoplankton distribution off NW Iberia in the summer upwelling season is strongly coupled to submesoscale processes.
- Ocurrence of Ostreopsis in two temperate coastal bays (SW iberia): Insights from the planktonPublication . Santos, Mariana; Oliveira, Paulo B.; Calixto De Jesus Moita Garnel, Maria Teresa; David, Helena; Caeiro, Maria Filomena; Zingone, Adriana; Amorim, Ana; D. Silva, AlexandraThe benthic genus Ostreopsis contains toxic-bloom forming species and is an important cause of concern in warm-temperate and tropical waters. On the coast of Portugal, NE Atlantic, the occurrence of Ostreopsis cf. siamensis and Ostreopsis cf. ovata has been reported since 2008 and 2011, respectively. This work aims to understand the favorable conditions for high concentrations of Ostreopsis cells in the plankton at two sites, Lagos and Lisbon Bays, located in the South and West coast of Portugal, respectively. This study is based on weekly Ostreopsis abundance data in the plankton, from 2011 to 2017, daily satellite and in situ sea surface temperature (SST), and meteorological and sea state parameters, namely wind stress and significant wave height. The molecular identification of local Ostreopsis spp. is also presented. The maximum cell densities occur between late-summer and autumn. The distribution range of Ostreopsis cf. ovata is restricted to the South coast, while Ostreopsis cf. siamensis has a wider distribution range, being also present on the West coast. In the study period, there was only one occurrence of Ostreopsis spp., in Lagos Bay, with concentrations within the alert phase of monitoring. In Lagos Bay, high Ostreopsis spp. concentrations were related with positive SST anomalies. These high concentrations were often recorded after a period of almost 2-weeks to more than 4-weeks of low sea state ( < 0.6 m), followed by short time events of onshore wind and moderate waves (0.6-1 m). The former conditions are interpreted as favoring bloom development on the substrate and the latter as causing the re-suspension of Ostreopsis cells in the water column. In Lisbon Bay, O. cf. siamensis occurred in the plankton in few occasions and no clear relation could be established with the studied environmental variables. It is here hypothesized that the recent records of O. cf. siamensis in Lisbon Bay may correspond to an early colonization stage of an invasion process. Knowledge gained on Ostreopsis dynamics along the Portuguese coast can be used for both the improvement of benthic harmful algal blooms (BHABs) monitoring in the region and as a basis to design forecasting models.
- Mesoscale dynamics and niche segregation of two Dinophysis species in Galician-Portuguese coastal watersPublication . Díaz, Patricio; Reguera, Beatriz; Calixto De Jesus Moita Garnel, Maria Teresa; Bravo, Isabel; Ruiz-Villarreal, Manuel; Fraga, SantiagoBlooms of Dinophysis acuminata occur every year in Galicia (northwest Spain), between spring and autumn. These blooms contaminate shellfish with lipophilic toxins and cause lengthy harvesting bans. They are often followed by short-lived blooms of Dinophysis acuta, associated with northward longshore transport, at the end of the upwelling season. During the summers of 1989 and 1990, dense blooms of D. acuta developed in situ, initially co-occurring with D.acuminata and later with the paralytic shellfish toxin-producer Gymnodiniumcatenatum. Unexplored data from three cruises carried out before, during, and following autumn blooms (13⁻14, 27⁻28 September and 11⁻12 October) in 1990 showed D. acuta distribution in shelf waters within the 50 m and 130 m isobaths, delimited by the upwelling front. A joint review of monitoring data from Galicia and Portugal provided a mesoscale view of anomalies in SST and other hydroclimatic factors associated with a northward displacement of the center of gravity of D. acuta populations. At the microscale, re-examination of the vertical segregation of cell maxima in the light of current knowledge, improved our understanding of niche differentiation between the two species of Dinophysis. Results here improve local transport models and forecast of Dinophysis events, the main cause of shellfish harvesting bans in the most important mussel production area in Europe.