7 Synthesis: Dredging pressures on coral

Description

Sediments released from dredging can reduce or block light, clog filtering and feeding apparatus and smother benthic organisms. Sediments can also affect many aspects of the reproduction and recruitment processes which underlie the maintenance of communities and their resilience to disturbance.

Particularly relevant to managing the risk of dredging projects around coral reefs is the phenomenon of multi-specific synchronous spawning of corals, where many (though not all) coral species spawn at predictable times of the year. Since some studies have indicated that the early life-history stages of corals are particularly sensitive to sediments (and since no evidence has been presented to the contrary), the precautionary principle has been applied to managing risks posed by elevated sediments during the mass spawning period.

Regulations in WA have required a shutdown of dredging operations shortly before and after the known synchronous spawning periods. These shutdown periods are referred to as Environmental Windows (EW). Theme 7 of the WAMSI Dredging Science Node addresses the environmental effects of sediments on the early life-history stages of corals, coral spawning Environmental Windows and shutdown procedures as applied to large-scale dredging projects in WA.

Aims

To address the environmental effects of sediments on the early life-history stages of corals, coral spawning Environmental Windows and shutdown procedures as applied to large-scale dredging projects in WA.

Outcomes

Project News 

• Sticky sediments and low sperm increase risk to coral fertilisation
• A thin layer of sediment impacts coral settlement behaviour
• Confidential information unlocks secrets to coral reproduction in Western Australia
• That sinking feeling: Suspended sediments can prevent the ascent of coral egg bundles
• Suspended sediments limit coral sperm availability
• Can dredging sediments affect the reproductive cycle of corals?
• Coral embryos make next-gen mucous cocoons

Reports

Gilmour J, Speed CW, Babcock R. (2016) Coral reproduction in Western Australia. PeerJ 4:e2010 https://doi.org/10.7717/peerj.2010

Jones R, Ricardo G.F., Negri A.P. (Sept 2015) Effects of sediments on the reproductive cycle of corals. Marine

Pollution Bulletin doi:10.1016/j.marpolbul.2015.08.021

Ricardo G, Jones R, Clode P, Humanes A, Giofre N, Negri A (2018) Sediment characteristics influence the fertilisation success of the corals Acropora tenuis and Acropora millepora. Marine Pollution Bulletin https://doi.org/10.1016/j.marpolbul.2018.08.001

Ricardo G.F., Jones R.J., Nordborg M, Negri A.P. (2017) Settlement patterns of the coral Acropora millepora on sediment-laden surfaces. Science of The Total Environment doi.org/10.1016/j.scitotenv.2017.07.153

Ricardo G.F., Jones R.J., Clode P.L., Negri A.P. (2016) Mucous Secretion and Cilia Beating Defend Developing Coral Larvae from Suspended Sediments. PLoS ONE 11(9): e0162743. doi:10.1371/journal.pone.0162743

Ricardo G.F., Jones R, Negri A, Stocker R (Feb 2016) That sinking feeling: Suspended sediments can prevent the ascent of coral egg bundles. Scientific Reports doi:10.1038/srep21567

Ricardo G.F., Jones R, Clode P, Humanes A, Negri A. (Dec 2015) Suspended sediments limit coral sperm availability Scientific Reports doi:10.1038/srep18084

 

Media

Presentations

Effects of dredging on coral reproduction (2017 WAMSI Research Conference)

Laboratory experimentation on the effects of dredging on fertilisation, larval development and settlement of corals. (2017 WAMSI Research Conference)

Coral reproduction in Western Australia. (2017 WAMSI Research Conference)