Model Initialization

Particle Initial Location (PIL) – We used super-individual particles to represent freshly hatched larvae, issued from a birth-pulse, where all eggs are produced at the same time. We used a bathymetric constraint insured spawning occurred shoreward of the 70 m isobath (Figure). We imposed this condition for computational efficiency as particles occurring further offshore were often entrained by the shoreward edge of Gulf Stream meanders, and carried beyond the shelf break where they became unable to reach nurseries and were consequently lost to recruitment. (pers. obs.; see also Lozier and Gawarkiewicz, 2001; Stegmann et al., 1999; Werner et al., 1999).

Spawning locations were further constrained by temperature. Acceptable spawning temperatures ranged from 13 to 24 °C (inclusive, Stegmann et al., 1999). Given the predominantly southward alongshore flow, and to estimate the effect of spawning latitude, we placed 7 discrete patches, each seeded with 300 particles, relative to seven7 potential nursery areas, subject to the aforementioned conditions.

These seven potential nursery areas were, from south to north (Figure), the Ocracoke Inlet / Pamlico Sound system (OcI/PS), Oregon Inlet / Albemarle Sound system (OI/AS), Chesapeake Bay (CB), Delaware Bay (DB), Little Egg Harbor / Great Bay system (LEH/GB), Hudson River / Lower Bay / Upper Bay (HR/LB/UB), and Long Island Sound / Narragansett Bay / Buzzard’s Bay system (LIS/NB/BB). Note that, for the present study, the temperature constraint restricted particle initialization to occur generally south of the Hudson River. The location of the southernmost nursery, OcI/PS, is somewhat peculiar relative to the others in that it is separated from the mid-Atlantic Bight by Cape Hatteras around which the shelf is at its narrowest on the ESPreSSO grid .

Particles were all initialized at a depth of 10m. To determine the temperature distribution at 10 m we used the same interpolation scheme as in LTRANS. Specifically, we interpolated temperature values along s-levels to produce a vertical profile at each particle’s horizontal (x- and y-) coordinates, we then determined temperature at the desired depth by fitting a tension spline to these profiles (additional details can be found in North et al., 2011). For this purpose, we used the first record of the ESPreSSO flow solution data set to determine the temperature distribution at 10 m over the model domain on the starting date.

QuaFEL research areas


Blue crab ecology

Multispecies interactions

Fisheries Oceanography

Elasmobranch ecology


Last revised: 1/18/2016