Assessing the risk of light reduction from natural sediment resuspension events and dredging activities in an inshore turbid reef environment

Heidi M Luter; Mari-Carmen Pineda; Gerard Ricardo; David S Francis; Rebecca Fisher; Ross Jones

doi:10.1016/j.marpolbul.2021.112536

Assessing the risk of light reduction from natural sediment resuspension events and dredging activities in an inshore turbid reef environment

Mar Pollut Bull. 2021 Sep:170:112536. doi: 10.1016/j.marpolbul.2021.112536. Epub 2021 Jun 11.

Authors

Heidi M Luter¹, Mari-Carmen Pineda¹, Gerard Ricardo¹, David S Francis², Rebecca Fisher³, Ross Jones⁴

Affiliations

¹ Australian Institute of Marine Science, Townsville, QLD and Perth, WA, Australia.
² School of Life and Environmental Sciences, Deakin University, Geelong, VIC, Australia.
³ Australian Institute of Marine Science, Townsville, QLD and Perth, WA, Australia; The UWA Oceans Institute University of Western Australia, WA, Australia.
⁴ Australian Institute of Marine Science, Townsville, QLD and Perth, WA, Australia; The UWA Oceans Institute University of Western Australia, WA, Australia. Electronic address: r.jones@aims.gov.au.

PMID: 34126443
DOI: 10.1016/j.marpolbul.2021.112536

Abstract

The reduction in benthic light from natural sediment resuspension events, dredging activities and clouds was quantified over multiple time periods (days to weeks) from a 3-year in-situ field study in the inshore turbid-zone coral communities of the Great Barrier Reef. The results were then used to examine the tolerance levels of three coral species and a sponge to light reduction and associated changes in spectral light quality (in conjunction with elevated sediment concentrations) in a 28-day laboratory-based study. All species survived the exposures but sub-lethal responses involving changes in pigmentation, lipids and lipid ratios were observed. A pocilloporid coral was the most sensitive taxon, with a 28-d EC10 value for bleaching (dissociation of the symbiosis) of 2.7 mol photons m² d^-1. The possibility of such light reduction levels occurring naturally and/or during maintenance dredging activities was then examined using the 3-year in-situ field study as part of a risk assessment.

Keywords: Bioeroding sponge; Corals; Dredging; Light availability; Suspended sediments; Turbidity.

MeSH terms

Animals
Anthozoa*
Coral Reefs*
Geologic Sediments
Physical Phenomena
Symbiosis