MEPS 494:191-203 (2013)  -  doi:10.3354/meps10572

Spatial differences in larval abundance within the coastal boundary layer impact supply to shoreline habitats

Kerry J. Nickols1,4,*, Seth H. Miller1, Brian Gaylord1,2, Steven G. Morgan1,3, John L. Largier1,3

1Bodega Marine Laboratory, University of California at Davis, Bodega Bay, California 94923, USA
2Department of Evolution and Ecology, University of California at Davis, Davis, California 95616, USA
3Department of Environmental Science and Policy, University of California at Davis, Davis, California 95616, USA
4Present address: Hopkins Marine Station, Stanford University, Pacific Grove, California 93950, USA

ABSTRACT: Explorations of the dynamics of nearshore regions of the coastal zone are missing from many efforts to understand larval transport and delivery to suitable habitats. Larval distributions in the coastal ocean are variable and depend on physical processes and larval behaviors, leading to biophysical interactions that may increase larval retention nearshore and bolster their return to natal sites. While recent evidence suggests that many larvae are retained within a few kilometers from shore, few studies incorporate measurements sufficiently close to shore to plausibly assess supply to the shoreline benthos. We measured cross-shore distributions of larvae of benthic crustaceans between 250 and 1100 m from shore (i.e. just beyond the surf zone) within the coastal boundary layer (CBL)—a region of reduced alongshore flow—and simultaneously quantified a suite of physical factors that may influence larval distributions. We found high larval abundance within the CBL, with a peak at 850 m from shore, and a decrease in abundance along the shoreward edge of the sampled transect. We also found distinctly different larval assemblages at outer stations within the CBL, as compared to inner stations that are more influenced by shoreline dynamics. These patterns persisted across sample dates, suggesting that the spatial structure of nearshore larval assemblages is at least somewhat robust to temporal changes in physical conditions. Thus, while larval abundance appears to be high within the CBL, larvae appear to be sparse within the narrow band of water adjacent to the surf zone. Low larval supply adjacent to suitable habitats has important implications for the coupling of supply and recruitment, and resulting dynamics of shoreline populations.


KEY WORDS: Dispersal · Invertebrate larvae · Retention · Nearshore · Transport


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Cite this article as: Nickols KJ, Miller SH, Gaylord B, Morgan SG, Largier JL (2013) Spatial differences in larval abundance within the coastal boundary layer impact supply to shoreline habitats. Mar Ecol Prog Ser 494:191-203

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