Influence of limestone and anthropogenic activities on land snail communities in Satun Province, Thailand

Abstract

Southeast Asia is renowned for its rich biodiversity and serves as a global hotspot for organisms. Satun Province, located in southern Thailand, represents a significant biogeographic and biodiversity region situated in the transition zone between the Indochinese and Sundaland hotspots. Thus, Satun Province has high diversity and abundance of organisms, especially land snails. However, Satun Province has been largely understudied for both diversity and biogeography. Our study aimed to investigate land snail communities, emphasizing comparisons between the mainland and island sites, and the influence of limestone and other rock types in Satun Province. Our exploration efforts identified a diverse land snail community comprising 17 families, which updated the total reported species in the province from 22 to 58 species. The results showed that islands had significantly greater land snail species richness and abundance, and larger Shannon index values in comparison to the mainland. Anthropogenic activities on the mainland led to habitat transformation and had detrimental impacts on native land snail diversity while promoting the spread of invasive species. In contrast, the presence of little-disturbed limestone habitats on some of the islands contributed to higher richness of land snails, as limestone areas are known for their high diversity and endemism. Snail communities varied along site characteristics; especially, limestone versus non-limestone areas and human activity levels (which were associated with national park protection), with limestone and protected areas having the highest diversity. Our study illustrates the value of protected areas as potential hotspots of biodiversity, especially for islands that are little disturbed by human activities and that have habitats that support high diversity, such as limestone outcrops. This study provides valuable insights into the biogeography of land snails in Satun Province and Southeast Asia and contributes to our understanding of the factors influencing land snail diversity.

Keywords: Biodiversity hotspot; Biogeography; Diversity; Human activities; Island; Land snail assemblages.