Diversity and abundance of gastropods in the intertidal zone of Muduing Bay, Zamboanga Peninsula, Philippines

Abstract

The Dumanquillas Bay Protected Landscape and Seascape (DBPLS) of the Zamboanga Peninsula in the Philippines is a leading fishing ground and source of income for thousands of fisherfolks of the different communities residing along the coast of the Peninsula. One of the coastal bays along the DBPLS has been subjected to severe human-induced pressures such as encroachment of the mangrove areas for human habitation, resource utilization, and construction of fish pens. It is perceived that these activities compounded with the effects of global climate change are considered threats to marine life in the area; thus, we investigated one of the groups of marine organisms that are generally considered a good indicator of the health of the marine ecosystem - the gastropods. Their diversity and relative abundance can be used as a useful measure in understanding the status of the bay. Determining the correlation between the diversity and abundance with conditions such as pH, salinity, dissolved oxygen, water temperature, and total suspended solids is also considered a good measure; thus was also done in the study. Only one site was found to have a high diversity index. Three species from two sampling sites were associated with pH, while the low species richness in one location was due to low dissolved oxygen. Other physicochemical parameters have no significant effects on the diversity and abundance of gastropods. These results indicate that the low diversity index observed can be primarily attributed more to anthropogenic activities in the area. While the area is included in the protected landscape, is still a need to study further the dynamics of the populations of the different species focusing on other possible environmental and anthropogenic factors affecting their biodiversity. The information that will be generated will be valuable in the proper establishment and management of fishponds in the bay, including appropriate practices for their conservation and sustainable utilization.