Chitosan reduces turbidity without negative effects on scleractinian coral

Removal of marine sediment to widen or deepen channels during dredge operations is needed to maintain coastal infrastructure and navigation, but the fine sediment generated by dredging increases turbidity and can impact water quality creating adverse impacts on coral reefs. Corals heavily rely on the photosynthetic byproducts generated by symbiotic algae; increased turbidity reduces light availability inhibiting photosynthesis resulting in harmful impacts to growth and survival of scleractinian coral. Chitosan is a biodegradable flocculant, derived from the exoskeletons of crustaceans, which may be incorporated into existing dredging activities to reduce turbidity and mitigate water quality impacts for protection and conservation of scleractinian coral. This study investigated the potential health impacts of chitosan on Atlantic scleractinian coral. In a 30-day laboratory-based experiment, chitosan did not impact growth on Acropora cervicornis or Pseudodiploria clivosa. Additionally, chitosan significantly reduced turbidity within 1 hour of addition and maintained lower turbidity than the sediment only treatment every hour measured. Our research adds to the limited knowledge of potential chitosan impacts on scleractinian corals and expands on its potential use for effective turbidity mitigation in coastal ecosystems where coral reefs are present.