An Initial Exploration into the Population Dynamics and Reproduction of Patelloida saccharina on Rocky Shores in Taklong Island National Marine Reserve (TINMR), Southern Guimaras, Philippines


by:Karen A. Villarta, Angel Florie Leigh Ontoy, Ian Kenneth D. Villanueva, Mary Antoinette D. Ybañez


The population dynamics and reproduction of the limpet Patelloida saccharina (Linnaeus, 1758) on rocky shores in Taklong Island, Guimaras were examined in September 2016 (Southwest monsoon; SW) and December 2016 (Northeast monsoon; NE). Transects were laid parallel to the shore at five different tidal heights and 10 quadrats (25cm x 25cm) were placed randomly along each transect. Shell lengths (SL) of limpets encountered in each quadrat, at every tidal height, were measured to the nearest 0.1 mm using a Vernier caliper. Limpets were observed to occupy the low shores, with sizes ranging from 5.5 to 39.3 mm during the SW monsoon and 3.2 to 38.9 mm during the NE monsoon. P. saccharina showed a significant seasonal pattern whereby more limpets were observed during the SW monsoon (108 ind) than the NE monsoon (78 ind). A separate group of 30 limpets, during each season, was also collected to investigate the reproductive characteristics, with SLs ranging from 20.7 – 32.8 mm for females and 21.9 – 34 mm for males. Sex ratio between males and females showed no significant differences between sampling periods (p > 0.05). Investment in gonads during the SW monsoon was higher than during the NE monsoon, showing seasonal differences in reproductive effort, with females showing higher GSI compared to males. The higher abundance and increased reproductive investment during the SW monsoon may indicate seasonal differences in food availability or a general reduction in external stress. Further research to elucidate the cause of the observed differences is needed.

Keywords: Intertidal, Limpet, Monsoon, Vertical Distribution, Abundance, GSI, Population Structure, Rocky Shore