Model-derived connectivity patterns along the western Iberian Peninsula: asymmetrical larval flow and source-sink cell

Abstract

Predicting the spatial and temporal patterns of marine larval dispersal and supply is a challenging task, requiring the use of novel approaches capable of capturing the inherent variability in the mechanisms involved. Biophysical models are emerging as important tools used to understand dispersal and recruitment of marine larvae on several scales, and are used here to investigate these problems in the Northeast Atlantic Iberian Upwelling system. We used a Regional Ocean Modelling System configuration coupled with an individual-based model in order to simulate diel vertical migration and estuary-reinvasion behaviours, growth and mortality of larvae of the common shore crab Carcinus maenas. With this simulation we aimed to hindcast coast-wide connectivity patterns under the atmospheric and river flow forcings of the years 2001 to 2009. In a previous study, this model had been shown to produce time series of larval supply to a single population, at daily frequencies, that were strongly correlated with observed time series. In the current application, the model predicts that along-shore advection of larvae is variable from year to year; is correlated with the annual North Atlantic Oscillation index, which reflects the strength and persistence of equatorward winds; and is usually asymmetric, with a predominant equatorward transport. The model also predicts a source-sink cell located between the Muros-Noia and Mondego estuaries, where populations in the north consistently act as net sources of larvae supplying net sink populations to the south. This source-sink cell appears to be related to the existence of habitat gaps, coast geo metry and an oceanographic retention effect associated with upwelling dynamics.

The oceanic concordance of phylogeography and biogeography: a case study in Notochthamalus

“…; Nolasco et al. ). For example, the insight that the depth at which chthamalid larvae have been observed offshore is not the depth at which coastal retention of larvae is maximized (e.g., deeper release points in the model, as shown in Figure , appear to require little or no fitness differential, compared to the depths at which larvae have been seen in prior studies) is useful for understanding life history evolution; similarly, the transitions in lineage frequency can happen over very short spans of coastline (e.g., Fig.…”

“…; Nolasco et al. ). Of course, there can also be instances of simple, neutral patterns of population structure arising from currents and ocean physics alone (Sunday et al.…”

“…; Nolasco et al. ; Sunday et al. ), although some explore most of a species’ range (Taylor and Hellberg ; Wares and Cunningham ; Cowen et al.…”

Nearshore Larval Retention and Cross-Shelf Migration of Benthic Crustaceans at an Upwelling Center

“…Elsewhere, postlarvae can navigate onshore to suitable settlement sites using hierarchies of cues that are effective over different spatial scales, including celestial bodies, polarized light, magnetic and electric fields, waves and tides, and acoustic, chemical and visual cues (Kingsford et al, 2002;Montgomery et al, 2006;Arvedlund and Kavanagh, 2009;Morgan, in press). Adding onshore navigation into individual based biophysical models in upwelling regions (Pfeiffer-Herbert et al, 2007;Carr et al, 2008;Petersen et al, 2010;Domingues et al, 2012;Drake et al, 2013;Nolasco et al, 2013) should reduce the scale of population connectivity even further, but onshore navigation remains to be documented for species in upwelling regimes (Morgan, in press). The ultimate goal is to determine realized population connectivity, reconciling evidence from studies of circulation, plankton, genetics and microchemistry.…”

The influence of discharge, current speed, and development on the downstream dispersal of larval nase (Chondrostoma nasus) in the River Danube

“…Observations of larvae moving along hydraulic gradients (Stoll and Beeck 2012), adapting swimming and drifting speeds to the prevailing flow regime (Hogan and Mora 2005) or regulating depth distribution according to currents (Kunze et al 2013), further emphasize an active response to the hydrodynamic environment. The interactive effects of temporally unstable hydrodynamics and ontogenetically variable larval behaviour are increasingly being used in oceanic dispersal models to gain more realistic simulation results (Vikebo et al 2011;Sponaugle et al 2012;Nolasco et al 2013).…”