Macro and mesoscale physical patterns in the Bay of Biscay

Abstract

The study area for this work includes all the southern edge of the Bay of Biscay, from the north-west Iberian Peninsula to the southern half of the French shelf. The principal aim of this article is to provide a complete overview of the physical oceanography of the area, mainly in its mesoscale aspects, of which there are few published studies, and the implications for early fish life history stages. The results showed the existence of two space and temporal scales for most of the physical processes that occur in the Bay of Biscay, a macroscale for seasonal time periods and a meso and submesoscale for the periods between seasons. The importance of local phenomena, such as upwelling or the variability of the Poleward Current, was observed. The interaction of both scales on these physical processes is discussed and the need for sampling at the submesoscale level to determine the distribution of ichthyoplankton is considered. Moreover, the mesoscale physical oceanography study is essential to improve the knowledge of interactions between strategies and environmental conditions that result in a significant mortality reduction in fish early stages.

Deep sea megafaunal assemblages off the northern Iberian slope related to environmental factors

“…The production in the area is greatly influenced by a seasonal coastal upwelling (spring and summer) and hydrographical mesoscale activity along the northwestern shelf-break (Gil, 2008). Lavín et al (2005) report that upwelling events are more common and intense to the west of Cape Peñas, and that this is a mechanism of spatial variability between the western and eastern parts of the Cantabrian Sea.…”

“…Lavín et al (2005) report that upwelling events are more common and intense to the west of Cape Peñas, and that this is a mechanism of spatial variability between the western and eastern parts of the Cantabrian Sea. This is a consequence of the geographical location of the western area, which is closer than the eastern one to the anticyclone edge of the Azores High, and hence more influenced by eastern winds (Gil, 2008). Because of this, coastal summer upwelling strength-and hence chlorophyll values-decrease eastwards (Gil, 2008), and following the trophic webs these differences are also reflected in the abundance of zooplankton (Lavín et al, 2005).…”

“…This is a consequence of the geographical location of the western area, which is closer than the eastern one to the anticyclone edge of the Azores High, and hence more influenced by eastern winds (Gil, 2008). Because of this, coastal summer upwelling strength-and hence chlorophyll values-decrease eastwards (Gil, 2008), and following the trophic webs these differences are also reflected in the abundance of zooplankton (Lavín et al, 2005). In spring (as a consequence of mountain snow melting), the southeasternmost corner of the Bay of Biscay is the area of greatest discharge of continental fresh water, mainly through French rivers.…”

“…In spring (as a consequence of mountain snow melting), the southeasternmost corner of the Bay of Biscay is the area of greatest discharge of continental fresh water, mainly through French rivers. During this season, a boundary between the warm salty western water and the cold fresh eastern water is located around Cape Peñas (Gil, 2008).…”

“…For instance, the strength of seasonal upwelling (Gil, 2008), estuarine outwelling (López-Jamar et al, 1992) and canyon funnelling (Sorbe, 1999) is particularly different between western (Atlantic) and eastern areas (Cantabrian Sea). Moreover, several studies have highlighted regional differences regarding other factors such as width and steepness of the shelf, and type of sediment (Rey and Medialdea, 1989;Serrano et al, 2006Serrano et al, , 2008.…”