A new study has revealed that coral reefs face more than twice as much coral disease risks at dredging sites than at control sites.
Joe Pollock, a PhD candidate, said that Corals require both light and food to survive and unfortunately, dredging impacts corals on two fronts; increased turbidity means less light for photosynthesis, while increased levels of sediment falling onto the coral can interfere with their ability to feed
He further explained that just like in any other organism, it seems that chronic stress can lead to increased levels of disease in corals.
Already low on energy, the corals then must spend further energy cleaning the extra sediment from their surface. Such an energy imbalance could lead to chronic coral stress. In the past 20 years, the frequency of coral disease has risen across the world, and has become a significant factor in global coral reef decline. In the Caribbean, disease has diminished coral cover by as much as 95 percent in some locations.
This was the first study to examine the link between dredging and coral disease in nature and it was found that the most common diseases affecting corals after dredging events were the 'white syndromes', where the coral tissues fall off, leaving behind exposed, white coral skeletons. These coral diseases are chronic, and there are fears that they may linger well after the completion of dredging operations.
Dr Britta Schaffelke from AIMS, said that numerous environmental stressors like turbidity and sedimentation have been suggested as potential drivers of coral disease.
The researchers concluded that a solid understanding of the impacts of dredging, sediment and turbidity on coral health would be essential in the development of well-informed management and monitoring strategies for vulnerable coral reef ecosystems.