MEPS 316:139-153 (2006)  -  doi:10.3354/meps316139

Coastal brachyuran decapods: settlement and recruitment under contrasting coastal geometry conditions

Alvaro T. Palma1,2,*, L. M. Pardo2,3, R. Veas1, C. Cartes1, M. Silva1, K. Manriquez1, A. Diaz1, C. Muñoz1, F. P. Ojeda1,2

1Departamento de Ecología, and 2Center for Advanced Studies in Ecology and Biodiversity, Pontificia Universidad Católica de Chile, Alameda 340 Casilla 114-D, Santiago, Chile
3Laboratorio Costero Calfuco, Instituto de Biología Marina ‘Jürgen Winter’, Universidad Austral de Chile, Casilla 567, Valdivia, Chile

ABSTRACT: The importance of coastal morphology, and its influence on the magnitude of larval delivery and subsequent recruitment patterns of brachyuran decapods, was investigated at a broad range of spatial and temporal scales along the central coast of Chile. Larvae were quantified through plankton net towing as well as by using artificial settlement collectors deployed at different depths, while the abundance of benthic stages was quantified via in situ SCUBA airlifting and visual surveys. The abundance of young-of-the-year (YOY) and of individuals older than 1 yr (>1 yr) was compared between sites with contrasting conditions of coastal exposure at peninsulas several hundred kilometers apart. Additionally, we pursued a temporally more detailed surveying program, which included more species, at the southernmost peninsula. From our results we conclude that: (1) in general, the abundance of Paraxanthus barbiger, the most abundant species throughout, was greater at all locations in 2003 compared with 2004 and it was also greater (particularly >1 yr individuals) at protected sites; (2) for most of the species, the abundance of megalopae and YOY was highly seasonal, with peaks during the austral spring and summer months; and (3) for at least 2 of the 4 species considered in the southernmost peninsula, the abundance of YOY and >1 yr individuals exhibited higher abundance at the protected site. In spite of our efforts, we failed to find significant correlation between local abundance of settlers on artificial collectors and YOY individuals that settled in nursery habitats directly below. Post-settlement mortality, operating very soon after settlement, is a likely explanation for this finding. Our study highlights the importance of considering factors such as coastal morphology together with the occurrence of post-settlement processes when studying coastal organisms with complex life cycles.

KEY WORDS: Recruitment · Settlement · Physical factors · Larval delivery · Brachyuran decapods · Coastal morphology · Larval supply

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