4 Synthesis: Coral response to dredging

Description

In Australia, and especially in sub-tropical and tropical northwestern Australia, there are many examples of current and planned major dredging projects where millions of cubic metres of sediments require removal. These volumes are significant by global standards and since the released sediments can reduce or block light, clog filtering and feeding apparatus and smother benthic organisms they carry a significant environmental risk. To manage this risk, there is a critical need to establish quantitative relationships between dredging-relating pressures and the responses for key biota, especially iconic and ecologically important groups such as corals.

Work is divided into four projects, with projects 1 and 2 involving analysis of existing data and reviews, project 3 involving laboratory manipulations and including project 4 involving field work. The work program is staggered and integrated, with projects 1 and 2 informing project 3. The field-work component (Project 4) is associated with recovery modelling [as opposed to deriving pressure-response relationships] as the latter was considered to be far too risky an approach given the uncertainty of field work.

Aims

• To better understand the effects of dredging and dredge spoil disposal on corals by identifying the principle mechanisms by which suspended and settling sediments affect adult colonies in the short and long term.
• To establish pressure-response relationships for relevant pressure parameters that will provide water quality guidelines for dredging projects around coral reef environments.
• To produce protocols that describe how to incorporate this information into environmental impact assessment and monitoring programs. This will reduce uncertainty and environmental risks associated with large scale dredging projects and provide a mechanism for industry to ensure compliance with regulatory conditions.

Outcomes

A ‘new’ sensor was developed to monitor sediment deposition in coral reef environments by increasing the number of measurement points and its surface complexity so that it more closely resembles a coral surface.

 

Project News 

• Dredging Science: Understanding how low light levels can affect coral health
• Branching corals are better at rejecting dredging sediment
• Study finds early warning triggers for corals during dredging operations
• Bleached corals have reduced capacity to clear sediment
• Scientists test new sediment sensor that mimics coral reef
• Sneezing corals: Mucous sheets and sediment exposure
• Light limitation affects coral health more than sediment
• DSN Report 4.3: Corals of the northwest of Western Australia: biogeography and considerations for dredging-related research
• Coral colonies respond to sediment with sheets of mucus
• New research determines dredging effects on seawater quality

Reports

Bessell-Browne P, Negri A.P., Fisher R, Clode P.L., Jones R (2017) Impacts of light limitation on corals and crustose coralline algae Scientific Reports doi:10.1038/s41598-017-11783-z

Bessell-Browne P, Negri A.P., Fisher R, Clode P.L., Jones R, (2017) Cumulative impacts: thermally bleached corals have reduced capacity to clear deposited sediment Scientific Reports doi:10.1038/s41598-017-02810-0

Bessell-Browne P, Fisher R, Duckworth A, Jones R, (2017) Mucous sheet production in Porites: an effective bioindicator of sediment related pressures Marine Pollution Bulletin 2017 http://dx.doi.org/10.1016/j.ecolind.2017.02.023

Bessell-Browne P, Negri A.P., Fisher R, Clode P.L., Duckworth A, Jones R, (2017) Impacts of turbidity on corals: The relative importance of light limitation and suspended sediments Ecological Indicators 2017 http://dx.doi.org/10.1016/j.marpolbul.2017.01.050

Duckworth A, Giofre N, Jones R (2017) Coral morphology and sedimentation Marine Pollution Bulletin doi.org/10.1016/j.marpolbul.2017.08.036

Fisher R, Bessell-Browne P, Jones R (2019) Synergistic and antagonistic impacts of suspended sediments and thermal stress on corals. Nature communications 10:2346. https://doi.org/10.1038/s41467-019-10288-9

Fisher R, Walshe T, Bessell-Browne P, Jones R. (2017) Accounting for environmental uncertainty in the management of dredging impacts using probabilistic dose–response relationships and thresholds. J Appl Ecol. doi.org/10.1111/1365-2664.12936

Fisher R, Stark P, Ridd P, Jones R (Dec 2015) Spatial Patterns in Water Quality Changes during Dredging in Tropical Environments PLOS DOI: 10.1371/journal.pone.0143309

Jones R, Fisher R, Bessell-Browne P (2019) Sediment deposition and coral smothering. PLoS ONE 14(6): e0216248. https://doi.org/10.1371/journal.pone.0216248

Jones R, Bessell-Brownea P, Fishera R, Klonowskic W, Slivkoffc M (Dec 2015) Assessing the impacts of sediments from dredging on corals Marine Pollution Bulletin doi:10.1016/j.marpolbul.2015.10.049

Jones R, Fisher R, Stark C, Ridd P (Oct 2015) Temporal Patterns in Seawater Quality from Dredging in Tropical Environments PLOS DOI: 10.1371/journal.pone.0137112

Whinney J, Jones R, Duckworth A, Ridd P (Dec 2016) Continuous in situ monitoring of sediment deposition in shallow benthic environments Coral Reefs DOI 10.1007/s00338-016-1536-7

Media

Presentations

Whinney J et al. Continuous in situ monitoring of sediment deposition in shallow benthic environments. (2017 WAMSI Research Conference)

Dredging and bleaching events (2017 WAMSI Research Conference)

Sub-lethal indicators of dredging pressures – mucous sheet production in Porites corals. (2017 WAMSI Research Conference)

Specific and interactive effects of total suspended solids, light attenuation and sediment deposition on adult corals. (2017 WAMSI Research Conference)