Assemblages of benthic foraminifera in Pujada Island, Davao Oriental, Philippines

Abstract

The present study investigated the composition, density, abundance, and diversity of benthic foraminifera, and their relationship with various physico-chemical parameters such as pH, salinity, temperature, and sediment grain size. Foraminifera were collected from the intertidal zone using sediment cores and extracted from the sediments through sieving. The extracted foraminifera were stained with Rose bengal solution and preserved with buffered formalin. A total of 9,459 individuals of foraminifera were identified, consisting of 39 species classified into four orders, 16 families, and 21 genera. The top three most abundant genera were Calcarina, Baculogypsina, and Amphistegina. The comparison (ANOVA) of the abundance of foraminifera among the six stations revealed highly significant differences (P= 0.000; df= 38). Station 1 exhibited the highest diversity of foraminifera on Pujada Island, as indicated by an H’ value of 3.06. Conversely, station 6 displayed the lowest diversity, with an H’ value of 1.59. The pH, salinity, and temperature values are all within acceptable limits for seawater. The decreased diversity observed in some stations are attributed by various factors, like site disturbance (accessibility to many tourists and availability of beach resorts) and the variation in sediment grain size composition. The findings suggest that generally, Pujada Island remains an undisturbed coastal area. As a result, this study provides a baseline for future monitoring of the impacts of natural and human-induced activities in the region, thereby recommending the use of foraminifera's as bioindicators for marine health.