The Early Development of the Short-Necked Clam, <i>Paphia undulata </i>(Born 1778) (Mollusca, Pelecypoda: Veneridae) in the Laboratory
Abstract
The population of Paphia undulata in Negros Occidental waters continues to decline due to unregulated harvesting because of the increasing demand for this resource. One potential effort to mitigate this problem is reseeding or stock enhancement of the natural population. For these efforts to be effective however, successful laboratory rearing and breeding of this species is a prerequisite. Thus, this study was conducted to describe the embryonic and larval development of P. undulata to provide information on laboratory larval rearing. Broodstock were collected during the natural spawning peak from Hinigaran, Negros Occidental and were maintained in a static system with a mean salinity and temperature of 36 ppt. and 26.7 OC, respectively and were fed with Isochrysis galbana, Chaetoceros calcitrans, and Tetraselmis tetrahele. Fertilized eggs started to divide 30 minutes after fertilization. Ciliated swimming blastulas were observed after 1.5 hours with an average shell length (SL) of 40 µm. These further developed into trocophore larvae (average SL 60µm) after 7 hours and into D-veliger (average SL 80 µm) after 12 hours. Fully developed D-larvae (average SL 90 µm) were attained after 17 hours. Larvae with completely developed umbo were observed on day 9 with an average SL of 140 µm. On day 13, larvae (average SL 220 µm) started to settle and metamorphose. Spontaneous spawning was observed during the peak of reproductive activities of P. undulata showing that collection of broodstock must be conducted during the peak of reproductive season to ensure successful spawning and production of viable gametes under laboratory conditions. Further experiments should be conducted to determine optimum conditions to improve survival rates of the larvae during settlement. The results corroborate other studies and help explain the derived information on the species' population and reproductive biology.
Issue
Section
Articles
Keywords
Paphia undulata; embryonic and larval development; reproductive biology; laboratory breeding; Negros Occidental
Submission of a manuscript implies: that the work described has not been published before (except in the form of an abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that its publication has been approved by all co-authors, if any, as well as by the responsible authorities at the institute where the work has been carried out; that, if and when the manuscript is accepted for publication, the authors agree to the automatic transfer of the copyright to the publisher; that the manuscript will not be published elsewhere in any language without the consent of the copyright holders; that written permission of the copyright holder is obtained by the authors for material used from other copyrighted sources; and that any costs associated with obtaining this permission are the authors’ responsibility.
