very coastal and benthic species, generally high in regions of limited geographical
extension (low genetic differentiation). However, for the ecosystems management
and fisheries assessment perspective, the connectivity at short and middle temporal
scale (i.e., within a year) is more variable and relevant influencing the population
dynamics (demographic connectivity) and the long-term populations’ persistence.
Connectivity research implies the development of varied research tools, ranging
from biophysical modelling, population genetics, tag and recapture, and otolith
microchemistry.
Hydrodynamic connectivity, understood as the capability of a flow to connect
separated areas by exchanging water parcels and their eventual biogeochemical
content, depends on the circulation patterns and their variability. Stable currents,
as the inflow of Atlantic water in the Mediterranean Sea through the Strait of
Gibraltar, promote the exchange of nonresident species among adjacent basins
without human intervention (Rodriguez et al. 1982; Whitehead et al. 1986). However, due to the highly unpredictable nature of geophysical flows, in which turbulence, mixing processes, and a wide spectrum of spatial and temporal scales are
involved, understanding and addressing this connectivity is one of the main challenges in modern ecology. Despite the many limitations due to the number of spatial
scales resolved and the unavoidably simplified role of the biotic component, numerical models are affordable tools that provide reliable results to delineate the main
patterns of connectivity (CIESM 2016; Werner et al. 2001; Conklin et al. 2018).
Models must increase resolution in coastal areas and resolve at least the mesoscale
satisfactorily (and as much submesoscale as possible) since these processes are
essential for connectivity. Thus, previous knowledge of the hydrodynamics, the
circulation patterns, and their variability become fundamental issues to build up
models in a given region. Biological traits and life history of the fish species
concerned, especially those impacting the early life stages, are equally important.
These issues are the focus of this chapter.
12.2 Hydrodynamic Connectivity and the Alboran Sea
Circulation
12.2.1 Mean Circulation Pattern and Mesoscale
and Seasonal Variability
Regarding the surface circulation of the Mediterranean Sea, the Alborán Sea may be
seen as a zonal-oriented basin that conveys the inflow of Atlantic water through the
Strait of Gibraltar toward the interior of the Mediterranean (Vargas-Yañez, this
book). This eastward flow, with typical speed of 1 m/s, is a meandering stream
(the Atlantic Jet, AJ hereinafter) that usually encircles two medium-sized anticyclonic gyres (referred to as WAG and EAG for Western and Eastern Alboran Gyres
hereinafter, see sketch in Fig. 12.1) where newly arrived Atlantic water accumulates
(Parrilla and Kinder 1987; Viudez et al. 1998; Vargas-Yañez, this book). They are
12 Biophysical Processes Determining the Connectivity of the Alboran Sea Fish. . .
461
extension (low genetic differentiation). However, for the ecosystems management
and fisheries assessment perspective, the connectivity at short and middle temporal
scale (i.e., within a year) is more variable and relevant influencing the population
dynamics (demographic connectivity) and the long-term populations’ persistence.
Connectivity research implies the development of varied research tools, ranging
from biophysical modelling, population genetics, tag and recapture, and otolith
microchemistry.
Hydrodynamic connectivity, understood as the capability of a flow to connect
separated areas by exchanging water parcels and their eventual biogeochemical
content, depends on the circulation patterns and their variability. Stable currents,
as the inflow of Atlantic water in the Mediterranean Sea through the Strait of
Gibraltar, promote the exchange of nonresident species among adjacent basins
without human intervention (Rodriguez et al. 1982; Whitehead et al. 1986). However, due to the highly unpredictable nature of geophysical flows, in which turbulence, mixing processes, and a wide spectrum of spatial and temporal scales are
involved, understanding and addressing this connectivity is one of the main challenges in modern ecology. Despite the many limitations due to the number of spatial
scales resolved and the unavoidably simplified role of the biotic component, numerical models are affordable tools that provide reliable results to delineate the main
patterns of connectivity (CIESM 2016; Werner et al. 2001; Conklin et al. 2018).
Models must increase resolution in coastal areas and resolve at least the mesoscale
satisfactorily (and as much submesoscale as possible) since these processes are
essential for connectivity. Thus, previous knowledge of the hydrodynamics, the
circulation patterns, and their variability become fundamental issues to build up
models in a given region. Biological traits and life history of the fish species
concerned, especially those impacting the early life stages, are equally important.
These issues are the focus of this chapter.
12.2 Hydrodynamic Connectivity and the Alboran Sea
Circulation
12.2.1 Mean Circulation Pattern and Mesoscale
and Seasonal Variability
Regarding the surface circulation of the Mediterranean Sea, the Alborán Sea may be
seen as a zonal-oriented basin that conveys the inflow of Atlantic water through the
Strait of Gibraltar toward the interior of the Mediterranean (Vargas-Yañez, this
book). This eastward flow, with typical speed of 1 m/s, is a meandering stream
(the Atlantic Jet, AJ hereinafter) that usually encircles two medium-sized anticyclonic gyres (referred to as WAG and EAG for Western and Eastern Alboran Gyres
hereinafter, see sketch in Fig. 12.1) where newly arrived Atlantic water accumulates
(Parrilla and Kinder 1987; Viudez et al. 1998; Vargas-Yañez, this book). They are
12 Biophysical Processes Determining the Connectivity of the Alboran Sea Fish. . .
461