Sediment from dredging severely impacts coral reefs

Study finds sediment accumulation on coral tissue is a “strong and consistent cause of tissue mortality”.

Research by the Australian Institute of Marine Science and the Australian Research Centre of Excellence have discovered that dredging severely impacts certain coral species.

The scientists conducted laboratory tests to develop lethal and sub-lethal benchmarks for coral exposed to dredging-generated sediments. The researchers tested two species of coral found in offshore locations to six levels of total suspended solids for 16 weeks, including a four week recovery period. They found after 12 weeks all coral tissue under the sediment had died, exposing white coral skeleton. Australian Institute of Marine Science senior principal research scientist Ross Jones says the sediment can affect coral by impacting their ability to feed as well as settling on the coral’s surface, causing it to expend energy cleaning itself. “It can also attenuate light—light attenuation is a key thing because a lot of these habitats are primary producer habitats so the corals and sea life need light to photosynthesise and light is attenuated by the sediments.  The study found that sediment accumulation on coral tissue was a “strong and consistent cause of tissue mortality” and resulted in the death of whole coral fragments over prolonged periods.

Read more at: http://phys.org/news/2012-09-offshore-dredging-severely-impacts-coral.html#jCp

Above photo taken by Cry-of-the-Water shows federally protected staghorn coral smothered with sediment from 2009 Broward County beach renourishment project.