The transport of fish larvae to estuarine nursery areas: A modeling study

Factors controlling the movement of fish larvae from coastal spawning environments to estuarine nursery areas are important to fish recruitment. In this dissertation, the role of physical processes in larval transport to estuarine nursery areas in the Aransas Pass, Texas, region are examined using a circulation model coupled with a passive particle transport model. Two phases of transport are examined: transport on the shelf to the tidal inlet and transport through the inlet to estuarine nursery areas.; Observed pulsing in the supply of red drum (Sciaenops ocellatus ) larvae to the tidal inlet is significantly correlated with modeled particle supply. This pulsing is not correlated with a specific physical process but results from the interaction of several factors affecting water movement, including low-frequency variations in water level and wind forcing. Simulations suggest that the primary spawning region for red drum larvae that utilize nursery habitat in the Aransas Pass region is located north of the inlet. Patterns in the trajectories of particles that successfully enter the inlet reveal that the nearshore region is an important conduit for larval transport to estuarine nursery habitat.; The interaction of physical processes with bathymetry produces temporal and spatial variability in supply of particles inside the bays. The approach path of particles outside the inlet determines the spatial transport patterns for inlets with branched channels and multiple bays. High larval abundances in Aransas Bay result from a combination of high larval input, limited habitat for settlement, and proximity of habitat to the inlet. Spatial settlement patterns depend upon the developmental stage of larvae entering the inlet, with competent larvae settling along leading edges of settlement habitat and pre-competent larvae settling in more central regions.; This study demonstrates that physical processes play an important role in determining larval supply and settlement in estuarine nursery areas. These results combined with observational and modeling studies of others suggest that the transport patterns identified in this study may be a common feature for recruitment of estuarine-dependent species in other locales.