Renewal time and the impact of harmful algal blooms on the extensive mussel raft culture of the Iberian coastal upwelling system (SW Europe)

Abstract

The extension and intensity of the upwelling season in the NW Iberian Peninsula (42º-43ºN) have decreased by 30% and 45% over the last 40 years, respectively. Accordingly, the renewal time (τ) of the Rías Baixas, four large coastal inlets where 15% of the World extraction of blue mussels occurs, has increased by 240%. We indirectly demonstrate here that the growing τ has caused the increasing occurrence of harmful microalgae in these embayments, dramatically affecting mussel raft cultivation. The equation            ) c exp(1 365 D 1 τ explains 80% of the variability of the number of days per year that mussels cannot be extracted from the hanging ropes because of the occurrence of harmful microalgae (D). The coefficient c 1 = 37± 2 days indicates that an average τ over the upwelling season of > 25±1 or 50± 3 days reduce mussel extraction to only 50% or 25% of the year, respectively.

Autotrophic and heterotrophic microbial plankton biomass in the NW Iberian upwelling: seasonal assessment of metabolic balance

“…Autotrophy in this region will depend on the frequency and intensity of upwelling events, which could promote an increase in carbon fixation mainly due to diatoms and so fuel the entire metabolism of the microbial community. However, in a possible future scenario with low upwelling intensity and frequency (Álvarez-Salgado et al 2008), this upwelling zone would become heterotrophic. In this case, the microbial community on the continental shelf should be powered by allochthonous organic inputs, with ex port from the nearby Rías Baixas, where autotrophy predominates (Arbones et al 2008), playing a pivotal role.…”

Integrative taxonomy supports the presence of two species of <em>Kyphosus</em> (Perciformes: Kyphosidae) in Atlantic European waters

“…The presence of Kyphosus species in the Mediterranean and the European Atlantic has been related to the warming of waters (Bañón 2004, Canas et al 2005. A rise of 0.24°C per decade has been observed in the Galician sea waters since 1974 (Gómez-Gesteira et al 2011), with a decrease in the extension and intensity of the upwelling seasons, responsible for the presence of colder coastal surface waters in summer, and an increase in the extension and intensity of the downwelling seasons, which favour the poleward current (Álvarez-Salgado et al 2008).…”

Harmful Algal Blooms in Eastern Boundary Upwelling Systems: A GEOHAB Core Research Project

“…These relationships were established on the ecological basis of a dynamic segregation of diatoms and dinoflagellates determined by the residual circulation of the Rías Baixas. Over the past 40 years, dinoflagellates, including lipophilic toxin producers, have been favored by a decrease in the extent and intensity of the upwelling season and a consequent increase in the renewal time of the rias (Álvarez-Salgado et al, 2008). In the smaller Ría de Ares-Betanzos (Ríaz Altas), Álvarez-Salgado et al (2011) show similar correlations between mussel harvesting closures due to lipophilic toxins and both coastal winds and precipitation.…”

“…Álvarez-Salgado et al (2008) applied statistical approaches to long-term data sets from the Rías Baixas on the Iberian coast to demonstrate a correlation between wind patterns on the shelf, which control the flushing of these large coastal inlets, and closures of mussel cultivation areas. These relationships were established on the ecological basis of a dynamic segregation of diatoms and dinoflagellates determined by the residual circulation of the Rías Baixas.…”