The role of land use change in the decline and recovery of coral reefs

Arizona State University, Scottsdale AZ

Investigators

Abstract

As the window for coral survival is quickly closing due to accelerating climate change impacts, there is an urgent need to identify and implement near-term solutions to stem coral declines and promote coral recovery. One essential component of this strategy that is underdeveloped is the reduction of land-based pollution inputs that harm corals. This project investigates the past and present impacts of land-based pollution on the health of coral reef ecosystems and assesses the potential for improved land use to increase reef resilience to climate change. To address the lack of reef water quality monitoring, this study combines data from the reef fossil record with historical and current data on coastal land use change from satellite imagery to link human alteration on land over the past 40 years with changes in reef water quality and coral health. This approach provides data at temporal scales that can lead to new understanding and monitoring of the long-term impacts of land alteration on coral reefs. This study uses established partnerships with local reef conservation organizations and research institutions to provide local reef managers with a range of potential scenarios for increasing coral reef health via improved land management. This project also provides students with interdisciplinary training in the traditionally separate fields of paleoecology, coral reef ecology, environmental geochemistry, and geography. Coral reefs in many regions are negatively impacted by a range of environmental and social factors. Over the past 50 years reefs have lost over half of their habitat forming corals due to the cumulative effects of climate change and local human impacts including fishing, introduction of invasive species, land use and land cover change, and associated land-based pollution. These declines threaten reef persistence and the critical ecosystem services reefs provide to millions of people. Although it is widely suspected that coral loss is associated with declining reef water quality, it has been difficult to quantify the link between land use and land cover change, reef water quality change, and coral declines because (1) the linkages between land-based activities and associated social-ecological impacts on coastal marine systems have been under-studied within the land system science community and (2) there is a lack of long-term data on human and reef ecosystem dynamics. This project combines paleoecological and geochemical techniques for reconstructing long-term reef water quality and ecosystem health with geospatial analyses of remote sensing data to track long-term anthropogenic change to Caribbean coastal watersheds. This approach addresses three key questions for reef management and conservation: (1) How have land system dynamics associated with human-induced land use conversion affected reef water quality over the past 40 years? (2) How has changing reef water quality, impacted by land-based pollution and runoff, affected coral reef health and resilience over centennial and millennial time scales? (3) What are the projected impacts of improved land use management on future coral reef health? This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.