Additive effects of temperature and sedimentation in coral recruits: Does reducing a local stressor increases coral resilience to ocean warming?
Francesca Fourney and Joana Figueiredo (corresponding author)
Corals worldwide are facing population declines due to global climate change and local anthropogenic impacts. Global climate change effects are hard to tackle but recent studies show that some coral species can better handle climate change stress when provided with additional energy resources. The local stressor that most undermines energy acquisition is sedimentation because it impedes coral heterotrophic feeding and their ability to photosynthesize. To investigate if reducing local sedimentation will enable corals to better endure ocean warming, we quantitatively assessed the combined effects of increased temperature and sedimentation (rate, grain size composition, and turbidity) on the survival of coral recruits of the species, Porites astreoides. We used sediment from a reef and a boat basin to mimic natural sediment (coarse) and anthropogenic (fine) sediment (common in dredging), respectively. Natural sediment did not to negatively impact coral survival, but anthropogenic sediment did. We found that the capacity of coral recruits to survive under warmer temperatures is improved when anthropogenic sediment is maintained at minimal levels (30mg.cm-2). Our study suggests that a reduction of US-EPA allowable turbidity from 29 Nephelometric Turbidity Units (NTU) to 7 NTU near coral reefs would facilitate coral recruit survival under current and higher temperatures.
Nova Southeastern University, Halmos College of Natural Sciences and Oceanography, Dania Beach, FL 33004 USA
*corresponding author: [email protected]
Francesca Fourney and Joana Figueiredo (corresponding author)
Corals worldwide are facing population declines due to global climate change and local anthropogenic impacts. Global climate change effects are hard to tackle but recent studies show that some coral species can better handle climate change stress when provided with additional energy resources. The local stressor that most undermines energy acquisition is sedimentation because it impedes coral heterotrophic feeding and their ability to photosynthesize. To investigate if reducing local sedimentation will enable corals to better endure ocean warming, we quantitatively assessed the combined effects of increased temperature and sedimentation (rate, grain size composition, and turbidity) on the survival of coral recruits of the species, Porites astreoides. We used sediment from a reef and a boat basin to mimic natural sediment (coarse) and anthropogenic (fine) sediment (common in dredging), respectively. Natural sediment did not to negatively impact coral survival, but anthropogenic sediment did. We found that the capacity of coral recruits to survive under warmer temperatures is improved when anthropogenic sediment is maintained at minimal levels (30mg.cm-2). Our study suggests that a reduction of US-EPA allowable turbidity from 29 Nephelometric Turbidity Units (NTU) to 7 NTU near coral reefs would facilitate coral recruit survival under current and higher temperatures.
Nova Southeastern University, Halmos College of Natural Sciences and Oceanography, Dania Beach, FL 33004 USA
*corresponding author: [email protected]