Marine Ecology

Growth versus breakdown
climate change threatens balance
reefs of the future

Nyssa Silbiger
University of Hawaii at Manoa

Title: Environmental drivers of the coral reef accretion-erosion balance in present and future ocean conditions.
Worldwide, declines in coral cover and shifts in coral reef community composition have raised concerns about whether reef accretion (reef growth by coral and other calcifiers) will continue to exceed reef erosion (reef breakdown by borers and grazers). Reef persistence is influenced by global and local anthropogenic factors, such as ocean warming, acidification, eutrophication, and overfishing, as well as natural environmental variability. Predicting reef response to environmental stress requires an understanding of both natural and anthropogenic environmental drivers of reef accretion and erosion, and how these drivers interact at different spatiotemporal scales. For my dissertation, I measured variation in accretion and erosion along a natural gradient to determine the dominant environmental drivers of accretion-erosion rates at fine (tens of meters) and broad (1000s of kilometers) spatial scales. I also used a controlled mesocosm experiment to directly examine the effects of global anthropogenic stressors (i.e., temperature and ocean acidification) on the coral reef accretion-erosion balance. My results highlight the importance of spatial scale in interpreting accretion-erosion data on coral reefs and also indicate that increases in reef erosion, combined with expected decreases in calcification, could accelerate the shift of coral reefs to an erosion-dominated system in a high CO2 world.