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Marine Ecology Progress Series

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MEPS 410:125-141 (2010)  -  DOI:

Shelf and estuarine transport mechanisms affecting the supply of competent larvae in a suite of brachyuran crabs with different life histories

A. O. Olaguer-Feliú1,*, A. A. V. Flores2, H. Queiroga3, J. I. González-Gordillo1

1CACYTMAR, Universidad de Cádiz, Campus Universitario de Puerto Real, 11510 Puerto Real (Cádiz), Spain
2Centro de Biologia Marinha—Universidade de São Paulo, Rodovia Manoel Hipólito do Rego, km 131.5, 11600-000, São Sebastião, São Paulo, Brazil
3Departamento de Biologia, CESAM—Centro de Estudos do Ambiente e do Mar, Universidad de Aveiro, 3810-193 Aveiro, Portugal

ABSTRACT: Supply of competent larvae to the benthic habitat is a major determinant of population dynamics in coastal and estuarine invertebrates with an indirect life cycle. Larval delivery may depend not only on physical transport mechanisms, but also on larval behavior and physiological progress to the competent stage. Yet, the combined analysis of such factors has seldom been attempted. We used time-series analyses to examine tide- and wind-driven mechanisms responsible for the supply of crab megalopae to an estuarine river under a major marine influence in SW Spain, and monitored the vertical distribution of upstream moving megalopae, their net flux and competent state. The species Panopeus africanus (estuarine), Brachynotus sexdentatus (euryhaline) and Nepinnotheres pinnotheres (coastal) comprised 80% of the whole sample, and responded in a similar way to tide and wind forcing. Tidal range was positively correlated to supply, with maxima 0 to 1 d after spring tides, suggesting selective tidal stream transport. Despite being extensively subjected to upwelling, downwind drift under the effect of westerlies, not Ekman transport, explained residual supply variation at our sampling area. Once in the estuary, net flux and competence state matched the expected trends. Net upstream flux increased from B. sexdentatus to P. africanus, favoring transport to a sheltered coastal habitat (N. pinnotheres), or to the upper estuary (P. africanus). Competence state was highest in N. pinnotheres, intermediate in B. sexdentatus and lowest in P. africanus, as expected if larvae respond to cues from adequate benthic habitat. P. africanus megalopae were found close to the bottom, not above, rendering slower upstream transport than anticipated.

KEY WORDS: Upwelling · Ekman transport · Downwind drift · Selective tidal stream transport · Larval net flux · Bay of Cádiz

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Cite this article as: Olaguer-Feliú AO, Flores AAV, Queiroga H, González-Gordillo J (2010) Shelf and estuarine transport mechanisms affecting the supply of competent larvae in a suite of brachyuran crabs with different life histories. Mar Ecol Prog Ser 410:125-141.

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