ABSTRACT: The simultaneously hermaphroditic sabellid Laonomealbicingillum Hsieh is the most dominant polychaete species in a mangrove estuary in northern Taiwan. Isolated individuals produced fertilized eggs which developed into normal larvae. Seminal receptacles were not found, indicating that individuals cannot store sperm. Ova, which were obtained directly from the coelom and inseminated by the same individual, developed into viable larvae and then settled successfully. The viability of embryos and newly settled larvae did not differ between self- and outcross fertilizations, indicating that self-fertilization has no immediate deleterious effects. Hypoosmotic seawater (salinity below 10o/oo) severely damaged sperm, resulting in stretched, perforated, or torn membranes. In contrast, seawater with 20 to 30o/oo salinity did not injure sperm morphology. In estuarine environments, hyposaline ambient water presents such great constraints that selfing may be an advantageous fertilization alternative for this simultaneously hermaphroditic species that is sessile and has broadcast spawning.

KEY WORDS: Self-fertilization · Hyposaline effects · Simultaneous hermaphrodite · Sabellid polychaete

Published in MEPS Vol. 147 (1997) on February 27
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997