Oil Palm to Coral Reefs: Effects of landuse intensification on coral reef systems

Tropical catchments are globally important centres for biodiversity and provide key ecosystem services. Relatively pristine until recent decades, deforestation and conversion to agriculture have led to unprecedented changes in the tropical landscape (Figure 1). For example 70% of the pristine forest of the Kinabatangan River, Sabah, Malaysia has been removed since the 1970’s, while oil palm agriculture has increased significantly. Associated increases in terrestrial sediment, nutrient, and pollutant load from rivers, is rapidly altering water quality in many nearshore settings, and is regarded as an especially significant threat to coral reef communities (1). This project seeks to quantify how the short term effects of terrestrial pollution in near-shore environments are linked to coral reef degradation through the novel coupling of geochemical and sedimentary/palaeoecological methods.
Annually banded massive corals provide ideal material for high-resolution environmental reconstructions, due to their long life span, and wide distribution in the tropical ocean. The student would develop high resolution geochemical proxy records of near shore water quality in coral skeletons from coral reefs proximal to two contrasting catchments in Sabah, Malaysia, one close to a pollution source and one further offshore, to develop records of terrestrial inputs over the last ~50 years at each site. To examine these changes in near shore chemistry in the context of changes in coral reef ecology, the student will develop high resolution coral palaeoecological records and sedimentary records derived from proximal reef framework cores (2) and apply CT scanning to create 3-D images of coral growth.
Specifically, the student will undertake retrieval of coral cores from the shallow water coral species Porites (Figure 2), ideal for geochemical reconstructions and abundant along coastal Sabah. In situ water quality and reef health measurements are available since 2007 and will allow modern calibration of the geochemical reconstructions and ecological impacts. Coral cores will be imaged using CT scanning to examine changes in reef health. Records of stable isotopic variations and traditionally used tracers of terrigenous inputs (e.g. d13C, Ba) will enable a multi-proxy approach to interpreting changes in influx of land-derived sediments carried from rivers into coral reef environments (2). Complimentary reef framework cores will be taken from adjacent sites to provide a detailed history of how coral communities have (or not) responded to these landuse changes. The PhD studentship will uniquely elucidate major trends in coral reef decline from integration of coral reef growth, terrestrial change, geochemical proxy, and climate records.