title: Sediment and turbidity associated with offshore dredging increase coral disease prevalence on nearby reefs.
abstract: In recent decades, coral reef ecosystems have declined to the extent that reefs are now threatened globally. While many water quality parameters have been proposed to contribute to reef declines, little evidence exists conclusively linking specific water quality parameters with increased disease prevalence in situ. Here we report evidence from in situ coral health surveys confirming that chronic exposure to dredging-associated sediment plumes significantly increase the prevalence of white syndromes, a devastating group of globally important coral diseases. Coral health surveys were conducted along a dredging-associated sediment plume gradient to assess the relationship between sedimentation, turbidity and coral health. Reefs exposed to the highest number of days under the sediment plume (296 to 347 days) had two-fold higher levels of disease, largely driven by a 2.5-fold increase in white syndromes, and a six-fold increase in other signs of compromised coral health relative to reefs with little or no plume exposure (0 to 9 days). Multivariate modeling and ordination incorporating sediment exposure level, coral community composition and cover, predation and multiple thermal stress indices provided further confirmation that sediment plume exposure level was the main driver of elevated disease and other compromised coral health indicators. This study provides the first evidence linking dredging-associated sedimentation and turbidity with elevated coral disease prevalence in situ. Our results may help to explain observed increases in global coral disease prevalence in recent decades and suggest that minimizing sedimentation and turbidity associated with coastal development will provide an important management tool for controlling coral disease epizootics.
authors.affiliation: ARC Centre of Excellence for Coral Reef Studies, School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia; AIMS@JCU, Australian Institute of Marine Science and James Cook University, Townsville, Queensland, Australia; Australian Institute of Marine Science, PMB 3, Townsville, Queensland, Australia.
authors.forename: F Joseph
authors.initials: FJ
authors.lastname: Pollock
authors.affiliation: ARC Centre of Excellence for Coral Reef Studies, School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia; AIMS@JCU, Australian Institute of Marine Science and James Cook University, Townsville, Queensland, Australia.
authors.forename: Joleah B
authors.initials: JB
authors.lastname: Lamb
authors.affiliation: Department of Parks and Wildlife, Marine Science Program, Kensington, Western Australia, Australia; Oceans Institute, University of Western Australia, Crawley, Western Australia, Australia.
authors.forename: Stuart N
authors.initials: SN
authors.lastname: Field
authors.affiliation: NOAA Coral Reef Watch, Townsville, Queensland, Australia; Marine Geophysical Laboratory, School of Engineering and Physical Sciences, James Cook University, Townsville, Queensland, Australia.
authors.forename: Scott F
authors.initials: SF
authors.lastname: Heron
authors.affiliation: Australian Institute of Marine Science, PMB 3, Townsville, Queensland, Australia.
authors.forename: Britta
authors.initials: B
authors.lastname: Schaffelke
authors.affiliation: Department of Parks and Wildlife, Marine Science Program, Kensington, Western Australia, Australia.
authors.forename: George
authors.initials: G
authors.lastname: Shedrawi
authors.affiliation: Australian Institute of Marine Science, PMB 3, Townsville, Queensland, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Bourne
authors.affiliation: ARC Centre of Excellence for Coral Reef Studies, School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia; AIMS@JCU, Australian Institute of Marine Science and James Cook University, Townsville, Queensland, Australia.
authors.forename: Bette L
authors.initials: BL
authors.lastname: Willis
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D057894:Coral Reefs; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data*; D019015:Geologic Sediments; D008954:Models, Biological; D012044:Regression Analysis; D013997:Time Factors; D014873:Water Pollutants / Q000009:adverse effects*; D014904:Western Australia
chemical_list: D014873:Water Pollutants