Global change driver impacts on the persistence of island ecosystems

Gabriela Schaepman-Strub

Annabelle Constance

Michael Schaepman

Owen Petchey

Summary:

Global change drivers present an imminent threat to ecosystems on low-lying islands which often harbour endemic species. The persistence of island ecosystems and endemic taxa is challenged by the progressive disappearance of suitable habitat as a result of an increasing sea level. In this project we hypothesise that sea level rise on Aldabra Atoll will influence coastal habitat (specifically mangrove) extent and species composition based on tolerance to salinity and sustained inundation. A combination of remotely sensed images and field surveys is used to investigate historical and contemporary changes in coastal species composition, habitat extent, and shoreline location as well as their drivers. Finally, to understand how sea level rise may impact the terrestrial biodiversity on Aldabra, we are modelling habitat inundation exposure of the Aldabra giant tortoise (Aldabrachelys gigantea). The results of this work will serve as a valuable baseline for islands facing an uncertain future in the face of sea level rise, specifically for atolls like Aldabra where distinct ecological communities occur.

Research:

The objectives of this project are threefold: to advance methods and detect significant patterns of change and their drivers occurring on Aldabra Atoll and inform management strategies in the region.

Figure 1: Image captured during a drone survey of a mature mangrove stand on Aldabra in 2015. Source: University Research Priority Programme