Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Harmful phytoplankton diversity and dynamics in an upwelling region (Sagres, SW Portugal) revealed by ribosomal RNA microarray combined with microscopyPublication . Danchenko, Sergei; Fragoso, Bruno; Guillebault, Delphine; Icely, John; Berzano, Marco; Newton, AliceThe study region in Sagres, SW Portugal, is subject to natural eutrophication of coastal waters by wind-driven upwelling, which stimulates high primary productivity facilitating the recent economic expansion of bivalve aquaculture in the region. However, this economic activity is threatened by harmful algal blooms (HAB) caused by the diatoms Pseudo-nitzschia spp., Dinophysis spp. and other HAB dinoflagellates, all of which can produce toxins, that can induce Amnesic Shellfish Poisoning (ASP), Diarrhetic Shellfish Poisoning (DSP) and Paralytic Shellfish Poisoning (PSP). This study couples traditional microscopy with 18S/28S rRNA microarray to improve the detection of HAB species and investigates the relation between HAB and the specific oceanographic conditions in the region. Good agreement was obtained between microscopy and microarray data for diatoms of genus Pseudo-nitzschia and dinoflagellates Dinophysis spp., Gymnodinium catenation and raphidophyte Heterosigma akashiwo, with less effective results for Prorocentrum. Microarray provided detection of flagellates Prymnesium spp., Pseudochattonella spp., Chloromorum toxicum and the important HAB dinoflagellates of the genera Alexandrum and Azadinium, with the latter being one of the first records from the study region. Seasonality and upwelling induced by northerly winds were found to be the driving forces of HAB development, with Pseudonitzschia spp. causing the risk of ASP during spring and summer upwelling season, and dinoflagellates causing the risk of DSP and PSP during upwelling relaxation, mainly in summer and autumn. The findings were in agreement with the results from toxicity monitoring of shellfish by the Portuguese Institute for Sea and Atmosphere and confirm the suitability of the RNA microarray method for HABs detection and aquaculture management applications.
- Dinoflagellate assemblages in the west iberian upwelling region (Sagres, Portugal) during 1994–2001Publication . Danchenko, Sergei; Dodge, John David; Icely, John; Newton, AliceChanges in the composition of dinoflagellates from 1994 to 2001 at a station influenced by wind-induced seasonal upwelling off SW Portugal were analyzed in relation to oceanography. 194 taxa of dinoflagellates were detected, the most frequent belonged to the genera Tripos, Protoperidinium, Dinophysis, Diplopsalopsis, Prorocentrum and Lingulodinium. The composition of dinoflagellate communities followed a seasonal pattern, in association with oceanographic forcing and change of upwelling conditions. Harmful species such as Dinophysis acuminata, D. acuta, D. caudata, Gonyaulax spp. and Lingulodinium polyedra were found to develop during the upwelling season, typically comprising summer and early autumn in the West Iberian upwelling system, and also occasionally in the conditions following upwelling events in other seasons.