Holocene Coral-Reef Development
With the continuing threat of climate change and other anthropogenic disturbances, the future of Florida's coral reefs is uncertain. One way to gain insights into the future trajectories of Florida's coral reefs is to investigate how they responded to environmental disturbances in the past.
Coral Cores - A Climate History Archive
The coral reefs of the Florida Keys Reef Tract (FKRT) are an invaluable natural resource. They protect shorelines by reducing wave energy, provide critical habitat to associated marine life, and contribute nearly $3 billion annually to local economies. Over the last several decades, coral reefs around the world have declined as a result of a variety of local- to global-scale perturbations; the reefs along the FKRT are no exception to this trend (Toth and others, 2014). With the continuing threat of climate change and other anthropogenic disturbances, the future of Florida's coral reefs is uncertain. One way to gain insights into the future trajectories of Florida's coral reefs is to investigate how they responded to environmental disturbances in the past (Toth and others, 2012; Toth 2013).
Cores collected from coral reef frameworks (fig. 1) can provide valuable records of reef development across millennial timescales. Using underwater hydraulic drilling (fig. 2), USGS researchers have been collecting cores from the reefs of the Florida Keys since the early 1970s. As a result, USGS-Saint Petersburg has amassed an extensive archive of coral reef cores. We are synthesizing records of existing reef cores and new cores collected during the course of this study (Fig. 3), to better understand the spatial and temporal trends in the development of Florida's reefs during the Holocene. The study is divided into three main parts: reconstructions of Holocene reef accretion, coral-reef paleoecology, and paleoenvironmental reconstructions.
Holocene Reef Accretion
We are using a combination of radiocarbon and U-series dating techniques to determine whether the timing of reef decline differed across the FKRT as a result of environmental differences. We will also calculate reef-accretion rates during the Holocene epoch, the period since the last glacial time, from ~10,000 years ago to present. Reef accretion is a measure of the net vertical growth of the reef over time that incorporates both calcification and erosion. By better understanding how reef accretion changed in response to environmental changes in the past, we can make predictions about how Florida's reef may respond to changes in climate, water quality, and sea-level rise in the future. This work compliments other studies in CREST that are investigating calcification rates and reef-scape biogeochemical processes on today's reefs.
Coral-Reef Paleoecology
We are using core records to reconstruct the species composition of reefs during the Holocene to determine how modern reef assemblages compare to the assemblages of the past. We are also analyzing Holocene coral skeletons to determine if coral growth rates have changed through time. We will compare these paleoecological data with our records of reef accretion to determine what ecological changes may have characterized changes in reef growth in the past.
Paleoenvironmental Reconstructions
We are working with the Reef History and Climate Change team in CREST to reconstruct environmental conditions on Florida’s reefs during the Holocene using geochemical archives from coral skeletons. We are also using the dating records from the cores to develop a model of sea-level changes on the FKRT over the last 10,000 years. This will allow us to directly measure the impact of environmental variability on the history of Florida’s reefs.
This research is part of the Coral Reef Ecosystem Studies (CREST) project. That project and other related tasks are listed below.
Coral Reef Ecosystem Studies (CREST)
Reef History and Climate Change
Coral Reef Seafloor Erosion and Coastal Hazards
Measuring Coral Growth to Help Restore Reefs
With the continuing threat of climate change and other anthropogenic disturbances, the future of Florida's coral reefs is uncertain. One way to gain insights into the future trajectories of Florida's coral reefs is to investigate how they responded to environmental disturbances in the past.
Coral Cores - A Climate History Archive
The coral reefs of the Florida Keys Reef Tract (FKRT) are an invaluable natural resource. They protect shorelines by reducing wave energy, provide critical habitat to associated marine life, and contribute nearly $3 billion annually to local economies. Over the last several decades, coral reefs around the world have declined as a result of a variety of local- to global-scale perturbations; the reefs along the FKRT are no exception to this trend (Toth and others, 2014). With the continuing threat of climate change and other anthropogenic disturbances, the future of Florida's coral reefs is uncertain. One way to gain insights into the future trajectories of Florida's coral reefs is to investigate how they responded to environmental disturbances in the past (Toth and others, 2012; Toth 2013).
Cores collected from coral reef frameworks (fig. 1) can provide valuable records of reef development across millennial timescales. Using underwater hydraulic drilling (fig. 2), USGS researchers have been collecting cores from the reefs of the Florida Keys since the early 1970s. As a result, USGS-Saint Petersburg has amassed an extensive archive of coral reef cores. We are synthesizing records of existing reef cores and new cores collected during the course of this study (Fig. 3), to better understand the spatial and temporal trends in the development of Florida's reefs during the Holocene. The study is divided into three main parts: reconstructions of Holocene reef accretion, coral-reef paleoecology, and paleoenvironmental reconstructions.
Holocene Reef Accretion
We are using a combination of radiocarbon and U-series dating techniques to determine whether the timing of reef decline differed across the FKRT as a result of environmental differences. We will also calculate reef-accretion rates during the Holocene epoch, the period since the last glacial time, from ~10,000 years ago to present. Reef accretion is a measure of the net vertical growth of the reef over time that incorporates both calcification and erosion. By better understanding how reef accretion changed in response to environmental changes in the past, we can make predictions about how Florida's reef may respond to changes in climate, water quality, and sea-level rise in the future. This work compliments other studies in CREST that are investigating calcification rates and reef-scape biogeochemical processes on today's reefs.
Coral-Reef Paleoecology
We are using core records to reconstruct the species composition of reefs during the Holocene to determine how modern reef assemblages compare to the assemblages of the past. We are also analyzing Holocene coral skeletons to determine if coral growth rates have changed through time. We will compare these paleoecological data with our records of reef accretion to determine what ecological changes may have characterized changes in reef growth in the past.
Paleoenvironmental Reconstructions
We are working with the Reef History and Climate Change team in CREST to reconstruct environmental conditions on Florida’s reefs during the Holocene using geochemical archives from coral skeletons. We are also using the dating records from the cores to develop a model of sea-level changes on the FKRT over the last 10,000 years. This will allow us to directly measure the impact of environmental variability on the history of Florida’s reefs.
This research is part of the Coral Reef Ecosystem Studies (CREST) project. That project and other related tasks are listed below.