Connectivity and larval dispersal along the Oregon coast estimated by numerical simulations

Abstract

[1] Connectivity and larval dispersal is explored off the Oregon coast during the summer upwelling season of 2001 using numerical ocean circulation simulations. The study region, with strong wind-driven currents and variable topography, is modeled using the Regional Ocean Modeling System (ROMS) forced by the Coupled Ocean Atmosphere Mesoscale Prediction System. A large number of passive particles as models of planktonic larvae are released daily for 120 days from 1 May to 28 August at depths of 1, 7, 15, 20, 50, and 75 m at every grid point shoreward of the 200 m isobath (on average 32 km offshore). The particles are transported by the three-dimensional currents of the model simulation. The competency time window for larval settlement is assumed to be in between days 15 and 35 after larvae are released. Larval settlement occurs at the shallowest location during the competency time window. Connectivity matrices reveal that some of the places of highest retention are similar to the proposed Oregon marine reserve sites, especially Cape Perpetua. The Heceta Bank region has high probabilities as both a source and a destination for settled larvae. Larvae released in the Heceta Bank region often settle at higher latitudes than their release location. There are strong correlations between the number of settled larvae shallower than the 50 m isobath and a 6 to 8 day running mean of the alongshore wind stress. Larvae are retained near the shore when the winds, averaged over the previous 6 to 8 days, are relaxed or downwelling favorable.Citation: Kim, S., and J. A. Barth (2011), Connectivity and larval dispersal along the Oregon coast estimated by numerical simulations,

Relationship between larval settlement, alongshore wind stress and surface temperature in a numerical model of the central California coastal circulation

“…The strong relationship between wind stress and settlement is consistent with some CCS modeling studies (Kim & Barth 2011), but differs from the calculations of buoyant larvae by Mitarai et al (2008). That work examined larval dispersal within an idealized, alongshore-uniform, wind-driven coastal upwelling system using stratification, bathymetry and surface forcing statistics representative of the CCS.…”

“…However, this variation in weights is not significant, indicating again that the PLD-averaged wind stress may be the best predictor of settlement. Kim & Barth (2011) found the cumulative nearshore abundance of both competent and pre-competent larvae released daily off the coast of Oregon was best predicted by a 6 to 8 d running mean of the wind stress. Our results for this 20 to 22 d PLD suggest that wind stress from release to competency contributes to settlement, consistent with recent idealized modeling experiments (Harrison & Siegel 2014).…”

“…This transport decreases nearshore retention and settlement during extended upwelling events (Kim & Barth 2011, Harrison & Siegel 2014) and over the entire upwelling season (Petersen et al 2010, Drake et al 2011). Yet other modeling studies suggest that this effectively 2-dimensional description of wind-driven larval transport is too simplistic.…”

Influence of larval behavior on transport and population connectivity in a realistic simulation of the California Current System

“…At large temporal and spatial scales, the relatively low swimming speeds of most larvae suggest they are advected passively by often chaotic and unpredictable ocean currents (Thorson 1950;Caley et al 1996;Metaxas 2001). Modest ocean currents can easily transport passive larvae hundreds of kilometers from their home populations in just a few weeks (Cowen et al 2003;Largier 2003;Carr et al 2008;Petersen et al 2010;Drake et al 2011;Kim and Barth 2011), yet populations persist. The apparent paradox indicates larvae have developed mechanisms to stay within or return to natal sites, travel from distant subpopulations by unknown pathways, or are supplied by some combination of these factors (Sponaugle et al 2002).…”

Effect of tide in oil spill prediction during Hebei spirit accident in Korea

“…Many studies were carried out with the trajectory models to simulate the spatial and temporal variations in the distribution of suspended matter, i.e., marine debris, pollutant drift, phytoplankton, zooplankton, egg-larvae, and giant jellyfish [12,16,17,18]. Those numerical experiments use basically same method of particle tracking in a 3D numerical model.…”