The Big Bend Region (BBR) in the Northeastern Gulf of Mexico (NEGOM) contains some of the country's most ecologically diverse and economically productive marine habitats. This region contains both spawning sites and nursery habitats for many key species of the region, such as the gag grouper (Mycteroperca microlepis). Adult gag spawn on offshore reefs along the continental shelf break each spring (Feb - April) (Coleman et al., 1996). Gag larvae are transported across the shelf until eventually settling as juveniles in the seagrasses of the coastal waters 30-60 days later (Koenig and Coleman, 1998). The study outlined in Todd et al. (2014) is the first to identify transport pathways from spawning grounds to seagrass beds in the Big Bend.
The primary tool used for this work is a very high-resolution (1/120°) configuration of the Regional Ocean Modeling System over the Big Bend Region of the Northeastern Gulf of Mexico (called the BBROMS). The BBROMS is nested within the 1/25° Gulf of Mexico HYCOM and configured for a domain that encompasses the entire BBR and the local shelf break. Simulations are run for 2004-2010 and are analyzed for their variability on time scales from synoptic, to seasonal, to interannual.
In addition to the hydrodynamic model, we incoroporate the Langrangian TRANSport Model (LTRANS) to track the fate of particles released into the simulated currents. Over 150,000 particles are released into the currents in "offline" mode each year to simulate the paths of larvae without any behavior (following only the ambient currents). Particles are followed for the mean pelagic larval duration for gag -- 45 days.