title: That sinking feeling: Suspended sediments can prevent the ascent of coral egg bundles.
abstract: Spawning synchrony represents a common reproductive strategy in sessile marine organisms and for broadcast spawning corals, buoyancy of egg-sperm bundles is critical to maximise fertilisation at the ocean surface. Here we demonstrate a novel threat to coral reproduction whereby buoyant egg-sperm bundles intercept and are "ballasted" by sediment grains on their journey to the ocean surface, preventing them from reaching the ocean surface and greatly reducing egg-sperm encounter rates. Empirical observations of this mechanism are successfully captured by a mathematical model that predicts the reduction in ascent probability and egg-sperm encounters as a function of sediment load. When applied to 15 m deep reefs, the model predicts that 10% and 50% reductions in egg-sperm encounters occur at 35 mg L(-1) and 87 mg L(-1) suspended sediment concentrations, respectively, and for a 5 m deep reef a 10% reduction occurs at 106 mg L(-1). These concentrations are commonly associated with sediment plumes from dredging or natural resuspension events. The potential for sediments to sink coral gametes highlights the need to carefully manage the timing of turbidity-generating human activities near reefs during spawning periods.
authors.affiliation: Australian Institute of Marine Science, Townsville, 4810, Queensland, and Perth, 6009, Western Australia, Australia.|Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, 6009, Western Australia, Australia.|Western Australian Marine Science Institution, Perth, 6009, Western Australia, Australia.|Oceans Institute, University of Western Australia, Perth, 6009, Western Australia, Australia.
authors.forename: Gerard F
authors.initials: GF
authors.lastname: Ricardo
authors.affiliation: Australian Institute of Marine Science, Townsville, 4810, Queensland, and Perth, 6009, Western Australia, Australia.|Western Australian Marine Science Institution, Perth, 6009, Western Australia, Australia.|Oceans Institute, University of Western Australia, Perth, 6009, Western Australia, Australia.
authors.forename: Ross J
authors.initials: RJ
authors.lastname: Jones
authors.affiliation: Australian Institute of Marine Science, Townsville, 4810, Queensland, and Perth, 6009, Western Australia, Australia.|Western Australian Marine Science Institution, Perth, 6009, Western Australia, Australia.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Negri
authors.affiliation: Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Roman
authors.initials: R
authors.lastname: Stocker
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000254:growth & development*; D057894:Coral Reefs; D005306:Fertilization / Q000187:drug effects*; D019015:Geologic Sediments / Q000737:chemistry; D005854:Germ Cells / Q000187:drug effects / Q000254:growth & development; D008297:Male; D008962:Models, Theoretical; D009792:Oceans and Seas; D010063:Ovum / Q000187:drug effects / Q000254:growth & development; D012098:Reproduction / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects / Q000254:growth & development