Coral survival in sediment rich coastal waters

5 Jul 2015 NUS scientists have recreated pulsed turbidity events to determine coral–sediment thresholds for active management.

Active management of anthropogenically driven sediment resuspension events (e.g. dredging) near coral reefs relies on an accurate assessment of coral thresholds to both suspended and deposited sediments. Yet the wide range of coral responses to sediments both within and amongst species has limited the ability to determine representative threshold values. This study reviews information available on coral physiological responses to a range of sediment loads at varying time frames and provides a novel approach to assess coral thresholds to suspended and deposited sediments.

A team led by Prof Peter TODD from the Department of Biological Sciences in NUS has provided improved estimates of coral thresholds to sediments for three common inshore turbid water coral species. These estimates suggest that inshore corals are resilient to elevated sediment loads that surpass current recommendations. However, it is the balance between sediment suspension and deposition, controlled by local hydrodynamics, that is potentially critical to coral survival in coastal regions. Realistic threshold values combined with modelling efforts should improve prediction of reef health and enable managers to react before coral mortality occurs.

The novel experimental setup involved purpose made chambers that provided the pulsed turbidity regime to corals. Corals were exposed to six turbidity events per day, of varying severity, for four weeks. [Image credit: Nicola BROWNE]

Reference

Browne NK, Tay JKL, Todd PA. “Recreating pulsed turbidity events to determine coral sediment thresholds for active management.” Journal of Experimental Marine Biology and Ecology. 466 (2015) 98.