Dinoflagellate Assemblages in the West Iberian Upwelling Region (Sagres, Portugal) During 1994–2001

Abstract

Changes 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.

Naturally and Anthropogenically Induced Lingulodinium polyedra Dinoflagellate Red Tides in the Galician Rias (NW Iberian Peninsula)

“…Blanco [13] suggested that temperature controls the rate of cyst germination, while Peña-Manjarrez [50] pointed out that when water temperature increases to approximately 17 • C, a "thermal window" is reached for this species, promoting cyst germination, together with a decrease of their relative abundance in surface sediments. This role of temperature was also proposed by other authors within a temperature range from 17 to 23 • C [15, [50][51][52]. Maximum threshold temperature may change according to geographical area, but the minimum temperature reported for cyst germination is always 17 • C. This is the case observed in the Ria of Coruña, when below 17 • C the seawater column remains stable and stratified during summer [39] and bottom waters do not meet the temperature requirements for cyst development (Figure 3).…”

A demographic model to forecast Dinophysis acuminata harmful algal blooms

“…Anschütz et al, 2022) as well as other Dinoflagellate species causing HABs in the North Atlantic (Gianella et al, 2021;Lima et al, 2022). These favourable conditions correspond to the spring-summer upwelling regime characterized by bright sunny days and nutrientrich cold waters, typical to the Iberian and Morocco coastal ocean (Ambar and Dias, 2008;Alvarez et al, 2010;Dıáz et al, 2013Dıáz et al, , 2016Moita et al, 2016;Leitão et al, 2019;Danchenko et al, 2022). In other locations on the North Atlantic, namely along the Bay of Biscay, British Isles and British Channel, the water is cold enough due to its higher latitude.…”

“…In other locations on the North Atlantic, namely along the Bay of Biscay, British Isles and British Channel, the water is cold enough due to its higher latitude. Consequently, the summer is the typical season for HAB of D. acuminata as well as other Dinoflagellate species in the North Atlantic (Smayda and Trainer, 2010;Dıáz et al, 2013Dıáz et al, , 2016Moita et al, 2016;Swan et al, 2018;Fernańdez et al, 2019;Gianella et al, 2021;Danchenko et al, 2022;Lima et al, 2022). Despite the environmental conditions favouring HABs being already reasonably understood, attempts to systematically forecast them have underachieve.…”

“…The other is to intensify the seawater collection effort only when conditions are favourable for any given HAB species. Considering D. acuminata, this sampling intensification should take place during the upwelling regime that takes place along the western Iberian shelf mainly during the summer season (Ambar and Dias, 2008;Alvarez et al, 2010;Leitão et al, 2019;Danchenko et al, 2022). Hence, weather forecasts of incoming north winds leading to upwelling, and the subsequent cooling of SST, may be used as triggers (in some semi-automatic way) to intensify the sampling effort, as well as to relax the remaining time.…”

Potential Effects of Climate Change on Offshore Aquaculture of the Mediterranean Mussel (Mytilus galloprovincialis, Lamarck, 1819) in Portugal

“…Of course this has vindicated the efforts of the producers in their request to the monitoring authorities to reduce the areas for specific zones along the Algarve coast and has demonstrated the importance of liaison between the producers and the governing authorities. The situation with HAB monitoring in Sagres is presented in more detail by Danchenko et al (2019Danchenko et al ( , 2022.…”