MEPS 350:1-17 (2007)  -  DOI:

Spatial variability of recruitment in the sand crab Emerita analoga throughout California in relation to wind-driven currents

Jennifer M. Diehl1, Robert J. Toonen2,*, Louis W. Botsford1

1Department of Wildlife, Fish and Conservation Biology, University of California, Davis, California 95616, USA
2School of Ocean and Earth Science and Technology, The Hawai’i Institute of Marine Biology, University of Hawai’i at Manoa, Coconut Island, PO Box 1346, Kane’ohe, Hawai’i 96744, USA
*Corresponding author. Email:

ABSTRACT: We compared recruitment of the sand crab Emerita analoga over 2 yr at 17 sites distributed along >800 km of the California coastline. We hypothesized that larvae of benthic invertebrates are retained by water circulation near headlands, and then redistributed alongshore north of the promontories during synoptic-scale relaxation in upwelling winds. We tested for a negative relationship between recruitment and distance north of 4 headlands: Point Arena, Point Reyes, Monterey Peninsula, and Point Conception. We also examined patterns of recruitment at sites east of Point Conception, within the Southern California Bight (SCB). Recruitment magnitude was predictable at a given site within a recruitment season (June through October), but not between the 2 years at each site. Recruitment of E. analoga north of Point Conception was negatively correlated with site distance north of a headland in 1998, but not in 1999. Upwelling indices in 1998 were not significantly different from the long-term average either north of Point Conception or within the SCB; in contrast, during 1999, upwelling was stronger than the 54 yr average at all sites north of Point Conception, but not at those within the SCB. Thus, the upwelling-relaxation mechanism appeared to operate effectively from Point Arena to Point Conception in 1998, when upwelling and wind stress were within long-term average levels, but not in 1999, when upwelling and wind stress were anomalously high. However, in the SCB, we observed similar magnitude and spatial patterns of recruitment in both years. One implication of our results is that the California coast may be composed of separate retentive cells of populations separated by headlands, which enhances population persistence, but the extent of larval loss from these cells remains unknown.

KEY WORDS: Upwelling · Relaxation · Wind stress · Inner shelf · Larval transport · Settlement

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Cite this article as: Diehl JM, Toonen RJ, Botsford LW (2007) Spatial variability of recruitment in the sand crab Emerita analoga throughout California in relation to wind-driven currents. Mar Ecol Prog Ser 350:1-17.

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