Fertilization success in Galeolaria caespitosa (Polychaeta: Serpulidae): gamete characteristics, role of sperm dilution, gamete age, and contact time

• Autores: Elena K. Kupriyanova
• Localización: Scientia Marina, ISSN 0214-8358, Vol. 70, Nº. Extra 3, 2006 (Ejemplar dedicado a: Scientifc advances in polychaete research), págs. 309-317
• Idioma: inglés
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• Resumen

  • Variability in gamete traits and the factors affecting fertilization success were studied in a common gregarious broadcast-spawning serpulid polychaete Galeolaria caespitosa. Variability of egg size and sperm velocity were not related to the adult size. High sperm concentrations (107-108 sperm. ml-1) were required to achieve fertilization rates of 60-80%. The gamete contact time required to achieve high fertilization rates (70-80%) in G. caespitosa did not exceed 5 minutes of gamete exposure given sufficiently high sperm concentrations. This suggests that attachment of sperm to the egg takes place very rapidly, and a short-term exposure to highly concentrated sperm is a common feature of fertilization ecology of this gregarious species. A sharp decline in fertilization rates at high sperm concentrations usually attributable to polyspermy was not observed. Sperm were motile for up to 6 hours after activation; however, swimming velocity and fertilization success decreased after 2 hours. Eggs of G. caespitosa were fertilizable up to 10 hours after spawning, but the number of embryos resulting from fertilizations by fresh sperm decreased after 2 hours. The gamete traits of G. caespitosa appear to have evolved to enable this sessile organism to reproduce under conditions of high population density and increased risk of polyspermy.