Diversity and distribution of protosteloid amoebae in the ridge-to-reef ecosystem of San Fernando City, Philippines

Protosteloid amoebae are a group of fungus-like protists that play critical ecological roles in nutrient cycling and microbial regulation within terrestrial ecosystems. Despite their ecological importance, their diversity and spatial distribution in Philippine landscapes remains understudied. Hence, this study randomly collected foliar litter on five timber upland forests and five coastal lowland forests to capture the range of microhabitats that may influence protosteloid diversity and investigate the spatial distribution of protosteloid amoebae across a ridge-to-reef ecosystem in San Fernando City, La Union, Philippines. Using established laboratory protocols and morphological examination, the following results were revealed: (i) eleven determinable species belonging to seven genera reflected a moderate sampling effort for the study, (ii) species diversity of protosteloid amoebae was higher in the upland than in the lowland but almost the same when microhabitats (aerial vs ground) were compared, and (iii) there were more similarities in composition in terms of substrates rather than elevation. These findings suggest that the distribution between upland and coastal lowland habitats is affected by possible ecological gradients and habitat specificity playing a vital role in shaping protist communities. This study highlights the urgent need for management strategies to protect unique microhabitats along the Philippine ridge-to-reef ecosystems and preserve the region's hidden microbial biodiversity.