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Marine Ecology Progress Series

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MEPS 409:107-119 (2010)  -  DOI:

Fertilization efficiency and gamete viability in the ascidian Pyura praeputialis in Chile

Patricio H. Manríquez1,*, Juan Carlos Castilla2

1Instituto de Biología Marina ‘Dr. Jürgen Winter’ and Laboratorio Costero de Recursos Acuáticos de Calfuco, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
2Departamento de Ecología, Facultad de Ciencias Biológicas and Center for Advanced Studies in Ecology and Biodiversity, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114–D, Santiago, Chile

ABSTRACT: In Chile, the ascidian Pyura praeputialis is an introduced species that occurs in intertidal and subtidal habitats restricted to Antofagasta Bay where it commonly forms extensive colonies that dominate mainly the rocky intertidal. Here we report the results of laboratory experiments conducted to determine the patterns of gamete spawning, and the consequences of the mode of reproduction, sperm age and sperm concentration on fertilization success. Our laboratory experiments indicate that the synchronous release of gametes takes place after the specimens are exposed to air, which is then followed by the formation of a biofoam in the rearing containers. Self fertilization with gametes obtained either by stripping or natural spawning failed to produce larvae or normal development, which occurred only when allosperm were used. Under laboratory conditions, fertilization success significantly decreased with sperm age and sperm concentration. Under field conditions, we recorded a negative effect of distance from areas with biofoam associated with spawning individuals on fertilization success. These findings suggest that it is selectively advantageous for this broadcast species to release gametes at low tide or after a period of emersion followed by biofoam formation. We suggest that this mechanism might have evolved to mitigate the difficulties of fertilization in turbulent aerated seawater, and to maximize fertilization success of short-lived gametes.

KEY WORDS: Broadcast spawner · Gamete longevity · Sperm concentration · Reproductive success · Synchronous spawning · Biofoam · Ascidian

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Cite this article as: Manríquez PH, Castilla JC (2010) Fertilization efficiency and gamete viability in the ascidian Pyura praeputialis in Chile. Mar Ecol Prog Ser 409:107-119.

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