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:Leni Yap-Dejeto, Abraham Cera, Jessica Labaja, Joseph Dominic Palermo, Alessandro Ponzo, Gonzalo


The whale shark is the world’s largest fish yet 60-90% of its diet is made up of the smallest prey, the zooplankton. The species is listed as endangered under the International Union for Conservation of Nature Red List of Threatened species. The biology and ecology of this species are largely unknown. Although parts of their movements have been mapped out, their food, which plays a major role in their travels and habitat use, is hardly studied. We therefor analysed zooplankton community composition along whale shark aggregation sites in Pintuyan, Southern Leyte, where sharks occur seasonally from November to June; and Oslob, Cebu, where they are hand-fed and found daily year- round. Water samples were taken in stations in each site during November 2014, January and February, 2015. In both sites with mostly microzooplankton of the Order Tintinnida was the most abundant group with a density of 2,000 indiv/m3 and 3,000 indiv/m3 in Pintuyan and Oslob, respectively. Other zooplankton observed were from classes Appendicularia, Ascidia, Bivalvia, Crustacea, Gastropoda, Ophiuroidae, Polychaeta, and Sarcodina. In total, the densities in both sites were not significantly different. Oslob registered a density value of 5,000 indiv/m3 and SB had 4,000 indiv/m3. In contrast, Pintuyan had a higher diversity value (2.75) than Oslob (2.36). Our results highlight that although whale sharks were not actively feeding near the sampling sites, the waters near their feeding sites are both abundant and rich in zooplankton diversity. Further studies to quantify and understand their target prey are needed.

Keywords: Microzooplankton, Whale shark, aggregation sites, Cebu