Coral Reef Seafloor Erosion and Coastal Hazards

Science Center Objects

Synchronized field work focused on geochemistry, geology, and metabolic processes overlaid on a habitat map of an entire reef to produce a synoptic overview of reef processes that contribute to carbonate precipitation and dissolution.

relationship between biology, chemistry, and physical and environmental processes in understanding ocean acidification

Infographic showing the relationship between biology, chemistry, and physical and environmental processes in understanding ocean acidification. (Credit: Kim Yates, USGS. Public domain.)

Coral reefs and the shallow seafloor surrounding them serve as natural barriers that protect coastal communities and shorelines from hazards such as storms, waves, and erosion. These ecosystems also provide socioeconomic stability for more than 200 million people worldwide that depend on them as food, recreational, cultural, and economic resources. The extent to which these ecosystems provide this service depends on whether or not coral reefs grow fast enough to keep up with rising sea level. However, many coral reef ecosystems are degrading due to human and natural impacts.

Quantifying coral reef seafloor accretion or erosion, and understanding the processes that underlie whether the reef is growing or degrading, are fundamental to questions of reef health, resiliency, and vulnerability of coastal communities to coastal and socioeconomic hazards.

Coral reefs are complex ecosystems where chemical, biological, and physical factors interact and strongly control the 3-dimensional structure of coral reefs and the surrounding seafloor that creates a natural barrier to coastal hazards and supports coral reef resources. We combine these areas of expertise using an integrated seascape approach to investigate how much erosion or accretion has occurred in coral reef ecosystems, its causes, and the effects of these changes on risks from storms, waves, and habitat loss.

For example, this USGS-CMGP task is the first ecosystem-wide study of seafloor erosion, changing coastal water depths, and effects on coastal storm and wave impacts along the Florida Keys Coral Reef Tract in South Florida. Regional-scale erosion measurements indicate that seafloor erosion is increasing water depths along the coastline much faster than sea level rise alone and increasing risks from storms and waves. USGS scientists are using these data along with measurements of waves and ocean currents to measure how much these changes have already increased risks to coastal communities, and how these risks will change in the future. A few select locations show seafloor accumulation. Localized studies are being conducted to help determine the causes of reef and seafloor erosion in some areas and accretion in other areas of the Florida Keys.

geochemistry, geology, metabolic processes

Infographisc showing reefscape synchronized field work: geochemistry, geology, metabolic processes.(Public domain.)

Geology and geophysics to measure erosion and accretion, the physical processes causing erosion, and impacts on storms and waves:

  • Sea-floor elevation measurements
  • ATRIS-derived habitat mapping
  • Sediment distributions (grain size and mineralogy)
  • Current and wave measurement and analysis

Chemistry to investigate the potential for chemical erosion of reefs:

  • Long-term autonomous seawater chemical and physical parameters (hourly sampling)
  • Diurnal and seasonal discrete seawater chemistry across the reefscape

Vertical chemistry profilesBiological processes affecting coral reef erosion and accretion are also investigated:

This research is part of the Coral Reef Ecosystem Studies (CREST) project.