Tidal and wind-event variability and the distribution of two groups of Pseudo-nitzschia species in an upwelling-influenced ría

Type Article
Date 2014-03
Language English
Author(s) Diaz Patricio A.1, 6, 7, Ruiz-Villarreal Manuel2, Velo-Suarez Lourdes1, 3, Ramilo Isabel1, Gentien Patrick3, Lunven Michel3, Fernand Liam4, Raine Robin5, Reguera Beatriz1
Affiliation(s) 1 : Inst Espanol Oceanog, Ctr Oceanog Vigo, Cabo Estay Vigo 36390, Spain.
2 : IEO, Ctr Oceanog A Coruna, La Coruna 15001, Spain.
3 : Inst Francais Rech Exploitat Mer, IFREMER, Ctr Brest, F-29280 Plouzane, France.
4 : Ctr Environm Fisheries & Aquaculture Sci, Lowestoft NR33 OHT, Suffolk, England.
5 : Natl Univ Ireland Univ Coll Galway, Ryan Inst, Galway, Ireland.
6 : Univ Austral Chile, Programa Invest Pesquera, Puerto Montt, Chile.
7 : Univ Austral Chile, Inst Acuicultura, Puerto Montt, Chile.
Source Deep-sea Research Part Ii-topical Studies In Oceanography (0967-0645) (Pergamon-elsevier Science Ltd), 2014-03 , Vol. 101 , P. 163-179
DOI 10.1016/j.dsr2.2013.09.043
WOS© Times Cited 17
Keyword(s) Pseudo-nitzschia spp., Upwelling-downwelling cycle, Spring-neap tidal variability, Thin layers, Circadian variability, Galician Rias
Abstract High-resolution physical and biological measurements were carried out in May-June 2007 during the ‘HABIT-Pontevedra 2007' survey in Ría de Pontevedra (Galician Rías Baixas, NW Spain) to study small-scale physical-biological interactions in the distribution of microphytoplankton, with special emphasis on harmful species. Longitudinal transects from the Ría to the adjacent shelf were sampled to describe the spring-neap tidal and circadian variability. An in situ particle profiler, a moored ADCP, and a towed undulating CTD (Scanfish) were used during the survey, which took place after an upwelling pulse at neap tides during a downwelling–upwelling cycle and coincided with the annual maximum of Pseudo-nitzschia spp. Cell maxima of P. seriata (2×106 cells L−1) and P. delicatissima (6×105 cells L−1) groups were observed during the first half of the cruise during downwelling, and a significant decrease in cell numbers occurred during subsequent relaxation-upwelling conditions. Thin layers were eroded during downwelling and formed again in the subsequent upwelling pulse. Cells of the P. seriata group were always dominant in terms of biomass but the contribution of the P. delicatissima group increased with stratification. Water exchange between the Ría and the adjacent shelf was mainly controlled by the upwelling/downwelling cycle, and tidal (both semidiurnal and spring-neap) variability appeared as a modulation of the response of the Ría circulation to wind variability. The circadian variability was regulated by tidal forcing, and Pseudo-nitzschia spp. maxima were associated with high stratification during low tide. The magnitude of spring-neap tidal and circadian variability has to be considered when designing and implementing water quality and harmful algae monitoring programmes. Blooms of Pseudo-nitzschia ssp. were not associated with the occurrence of domoic acid in shellfish even when Pseudo-nitzschia australis was dominant. These results confirm that just cell densities of the potential toxin producer are not enough for early warning in monitoring of Pseudo-nitzschia events.
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Diaz Patricio A., Ruiz-Villarreal Manuel, Velo-Suarez Lourdes, Ramilo Isabel, Gentien Patrick, Lunven Michel, Fernand Liam, Raine Robin, Reguera Beatriz (2014). Tidal and wind-event variability and the distribution of two groups of Pseudo-nitzschia species in an upwelling-influenced ría. Deep-sea Research Part Ii-topical Studies In Oceanography, 101, 163-179. Publisher's official version : https://doi.org/10.1016/j.dsr2.2013.09.043 , Open Access version : https://archimer.ifremer.fr/doc/00157/26794/