Neustonic distribution of decapod planktonic stages and competence of brachyuran megalopae in coastal waters
Fabiana T. Moreira A , Joseph Harari A and Augusto A. V. Flores B CA Universidade do Estado de São Paulo. Programa de Ciência Ambiental. Rua do Anfiteatro 181, Colméia Favo 14. Cidade Universitária, 05508-900, SP, Brazil.
B Universidade Estadual Paulista. Campus do Litoral Paulista – Unidade de São Vicente, Praça Infante D. Henrique, s/n. Parque Bitaru, 11330-205. São Vicente, SP, Brazil.
C Corresponding author. Email: guca@csv.unesp.br
Marine and Freshwater Research 58(6) 519-530 https://doi.org/10.1071/MF07002
Submitted: 9 January 2007 Accepted: 5 April 2007 Published: 25 June 2007
Abstract
Settlement rate may not reflect larval supply to coastal waters in different marine invertebrates and demersal fishes. The importance of near-shore oceanography and behaviour of late larval stages may be underestimated. The present study conducted neustonic sampling over station grids and along full-length transects at two embayments in south-eastern Brazil to (1) compare diurnal and nocturnal occurrence of most frequent decapod stages to assess their vertical movements, (2) describe the formation of larval patches and (3) measure competence of crab megalopae according to their distance to recruitment grounds. Several shrimp species apparently undergo a diel vertical migration, swimming crab megalopae showed no vertical movements and megalopae of the intertidal crab Pachygrapsus transversus revealed a reversed vertical migration. During the day, crab megalopae aggregated in convergence zones just below surface slicks. These larvae consisted of advanced, pre-moult stages, at both mid-bay and near-shore patches. Competence, measured as the time to metamorphosis in captivity, was similar between larval patches within each taxon. Yet, subtidal portunids moulted faster to juveniles than intertidal grapsids, possibly because they were closer to settlement grounds. Megalopae of Pachygrapsus from benthic collectors moulted faster than those from bay areas. These results suggest that alternative vertical migration patterns of late megalopae favour onshore transport, and actual competence takes place very close to suitable substrates, where larvae may remain for days before settlement. Lack of correlation between larval supply and settlement for Pachygrapsus suggests that biological processes, besides onshore transport, may play an important role in determining settlement success of coastal crabs.
Additional keywords: larval supply, settlement, vertical migration.
Acknowledgements
This study would have been impossible without the help of numerous people in the field. We specially thank our labmates James Lee, Marília Bueno, Eduardo Gigliotti, Fernando Perina, Christiano Mansur, Larisse Perez, Ricardo Ota, Ana Mazzuco and Sandra Araújo for their dedication during the intensive sampling agenda. We are also grateful to Dr Rogério Costa (Universidade Estadual Paulista, Campus de Bauru) and Dr Sergio Bueno (Universidade de São Paulo, Department of Zoology) for their help in the identification of shrimp species, and to Sergio Rosso (Universidade de São Paulo, Department of Ecology) for his assistance in statistical multivariate analyses. Thanks are also due to three anonymous reviewers who helped improving the manuscript. This study was supported by research funds granted by the Fundação de Amparo à Pesquisa do Estado de São Paulo (01/11156-4, 04/11781-4) and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (474855-2004).
Aidar, E. , Gaeta, S. A. , Gianesella-Galvão, S. M. F. , Kutner, M. B. B. , and Teixeira, C. (1993). Ecossistema costeiro subtropical: nutrientes dissolvidos, fitoplâncton e clorofila-a e suas relações com as condições oceanográficas na região de Ubatuba, SP. Publicação especial do Instituto Oceanográfico, Sao Paulo 10, 9–43.
Costa, R. C. , Fransozo, A. , Melo, G. A. S. , and Freire, F. A. M. (2003). Chave ilustrada para identificação dos camarões Dendrobranchiata do litoral norte do Estado de São Paulo, Brasil. Biota Neotropica 3, 1–12.
Incze, L. S. , and Wahle, R. A. (1991). Recruitment from pelagic to early benthic phase in the lobster Homarus americanus. Marine Ecology Progress Series 79, 77–87.
Milicich, M. J. , Meekan, M. G. , and Doherty, P. J. (1992). Larval supply: a good predictor of recruitment of three species of reef fish (Pomacentridae). Marine Ecology Progress Series 86, 153–166.
Shanks, A. L. (2006). Mechanisms of cross-shelf transport of crab megalopae inferred from a time series of daily abundance. Marine Biology 148, 1383–1398.
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Steele, M. A. , Malone, J. C. , Findlay, A. M. , Carr, M. H. , and Forrester, G. E. (2002). A simple method for estimating larval supply in reef fishes and a preliminary test of population limitation by larval delivery in the kelp bass Paralabrax clathratus. Marine Ecology Progress Series 235, 195–203.
Valles, H. , Sponaugle, S. , and Oxenford, H. A. (2001). Larval supply to a marine reserve and adjacent fished area in the Soufrière Marine Management Area, St Lucia, West Indies. Journal of Fish Biology 59, 152–177.
