Influence of coastal uplift and subsidence on the mangrove-associated crab community in the Andaman Islands, India

Abstract

The 2004 Sumatra-Andaman earthquake caused vertical ground movements (uplift and subsidence), which had a profound negative impact on the mangrove ecosystem of the Andaman and Nicobar Islands. Studies post-catastrophe largely delved into estimating the severity of degradation through changes in coastal vegetation cover. However, the implications of coastal uplift (sea level drop-SLD), and coastal subsidence (sea level rise-SLR) on the mangrove crab community remain largely unexplored. Therefore, to understand the impact of SLD and SLR on the diversity and zonation patterns of the mangrove crab community, we surveyed nine mangrove sites across the Andaman Islands representing various uplift (n = 4), subsidence (n = 4) and no-change scenarios (n = 1). We observed 57 distinct crab species in the control site (n = 57) followed by subsided sites (n = 45–54) and uplift sites (n = 20–37). The crab zonation pattern varied between the subsided and uplift habitats, based on their spatial distribution within the intertidal zone. Both, the transgression (towards land) and progression (towards the sea) of the crab community were evident in SLR and SLD scenarios, respectively. The current study serves as an important baseline for the long-term monitoring of mangrove crabs, which would help better understand the ecological response of mangrove crabs to the change in sea levels.