Reef History and Climate Change Active
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.
Corals as Paleo-environmental Archives
In order to better understand how the morphology and ecology of our coastal reefs has changed during the Holocene (past 10,000 years), we are analyzing coral skeletons to document past environmental changes and determine the relationships between the changing environment and coral growth. This information is critical to our understanding of the natural history of coral reefs and will provide clues to the future of reef accretion processes and climate change.
Scleractinian or "hard" corals deposit a skeleton of calcium carbonate (CaCO3), and serve as important geochemical archives for the reconstruction of paleo-environmental conditions on the reef. Mound corals are long-lived (100-300 years) and their skeletons have alternating light and dark layers that result from seasonal changes in growth rates. The couplets of light and dark layers represent annual bands, similar to tree rings, that can be used to determine the age of the coral skeleton. Variations in the chemical composition of the skeleton can be calibrated to environmental parameters such as seawater temperature, salinity, and pH as the coral grows.
Coral Geochemistry
In order to generate a time series of environmental variability, we drill a path of continuous samples along the growth axis of a coral using a computer driven triaxial micro-milling machine. This results in sub-annual sampling with 10-20 samples/year, depending on the coral linear extension rate. Using this approach we can reconstruct centuries-long records of seasonally resolved δ18O and Sr/Ca from long-lived Atlantic coral species such as Siderastraea siderea and Montastraea faveolata.
The Strontium to Calcium ratio (Sr/Ca) of the coral aragonite is related to the water temperature at which a coral calcifies. This is because Sr2+ and Ca2+ are both divalent cations with similar properties (they occupy the same column in the periodic table), so Sr2+ can substitute for Ca2+ in the CaCO3 of coral aragonite. As temperature increases, there is less Sr2+ substitution, and the Sr/Ca ratio decreases. The Sr/Ca to temperature relationship can differ between different species and different colonies of the same species of coral. We have empirically determined the Sr/Ca-temperature calibration equations for both M. faveolataand S. siderea in Dry Tortugas National Park, and applied those calibrations to time series covering the past 100-300 years.
The oxygen isotopic composition (δ18O) of coral aragonite is related to the temperature and the salinity of seawater. We are pairing Sr/Ca and δ18O measurements in corals to make inferences about past changes in temperature and salinity.
We are also exploring additional geochemical proxies in corals (e.g., B/Ca, Ba/Ca, δ11B, Li/Ca), which may tell us more about water nutrients, pH, salinity and temperature.
This research is part of the Coral Reef Ecosystem Studies (CREST) project. That project and other releated tasks are listed below.
Coral Reef Ecosystem Studies (CREST)
Holocene Coral-Reef Development
Coral Reef Seafloor Erosion and Coastal Hazards
Measuring Coral Growth to Help Restore Reefs
Below are publications associated with this project.
Fidelity of the Sr/Ca proxy in recording ocean temperature in the western Atlantic coral Siderastrea siderea
Multi-species coral Sr/Ca-based sea-surface temperature reconstruction using Orbicella faveolata and Siderastrea siderea from the Florida Straits
The relationship between the ratio of strontium to calcium and sea-surface temperature in a modern Porites astreoides coral: Implications for using P. astreoides as a paleoclimate archive
A reconstruction of sea surface temperature variability in the southeastern Gulf of Mexico from 1734 to 2008 C.E. using cross-dated Sr/Ca records from the coral Siderastrea siderea
Sr/Ca proxy sea-surface temperature reconstructions from modern and holocene Montastraea faveolata specimens from the Dry Tortugas National Park
Linear extension rates of massive corals from the Dry Tortugas National Park (DRTO), Florida
Holocene core logs and site methods for modern reef and head-coral cores - Dry Tortugas National Park, Florida
St. Petersburg Coastal and Marine Science Center's Core Archive Portal
Holocene core logs and site statistics for modern patch-reef cores: Biscayne National Park, Florida
Coral reefs, present and past, on the west Florida shelf and platform margin: Chapter 4
Patch-reef morphology as a proxy for Holocene sea-level variability, Northern Florida Keys, USA
Utility of shallow-water ATRIS images in defining biogeologic processes and self-similarity in skeletal scleractinia, Florida reefs
Below are news stories associated with this project.
- Overview
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.
Corals as Paleo-environmental Archives
In order to better understand how the morphology and ecology of our coastal reefs has changed during the Holocene (past 10,000 years), we are analyzing coral skeletons to document past environmental changes and determine the relationships between the changing environment and coral growth. This information is critical to our understanding of the natural history of coral reefs and will provide clues to the future of reef accretion processes and climate change.
Scleractinian or "hard" corals deposit a skeleton of calcium carbonate (CaCO3), and serve as important geochemical archives for the reconstruction of paleo-environmental conditions on the reef. Mound corals are long-lived (100-300 years) and their skeletons have alternating light and dark layers that result from seasonal changes in growth rates. The couplets of light and dark layers represent annual bands, similar to tree rings, that can be used to determine the age of the coral skeleton. Variations in the chemical composition of the skeleton can be calibrated to environmental parameters such as seawater temperature, salinity, and pH as the coral grows.
Coral Geochemistry
In order to generate a time series of environmental variability, we drill a path of continuous samples along the growth axis of a coral using a computer driven triaxial micro-milling machine. This results in sub-annual sampling with 10-20 samples/year, depending on the coral linear extension rate. Using this approach we can reconstruct centuries-long records of seasonally resolved δ18O and Sr/Ca from long-lived Atlantic coral species such as Siderastraea siderea and Montastraea faveolata.
The Strontium to Calcium ratio (Sr/Ca) of the coral aragonite is related to the water temperature at which a coral calcifies. This is because Sr2+ and Ca2+ are both divalent cations with similar properties (they occupy the same column in the periodic table), so Sr2+ can substitute for Ca2+ in the CaCO3 of coral aragonite. As temperature increases, there is less Sr2+ substitution, and the Sr/Ca ratio decreases. The Sr/Ca to temperature relationship can differ between different species and different colonies of the same species of coral. We have empirically determined the Sr/Ca-temperature calibration equations for both M. faveolataand S. siderea in Dry Tortugas National Park, and applied those calibrations to time series covering the past 100-300 years.
The oxygen isotopic composition (δ18O) of coral aragonite is related to the temperature and the salinity of seawater. We are pairing Sr/Ca and δ18O measurements in corals to make inferences about past changes in temperature and salinity.
We are also exploring additional geochemical proxies in corals (e.g., B/Ca, Ba/Ca, δ11B, Li/Ca), which may tell us more about water nutrients, pH, salinity and temperature.
- Science
This research is part of the Coral Reef Ecosystem Studies (CREST) project. That project and other releated tasks are listed below.
Coral Reef Ecosystem Studies (CREST)
The specific objectives of this project are to identify and describe the processes that are important in determining rates of coral-reef construction. How quickly the skeletons of calcifying organisms accumulate to form massive barrier-reef structure is determined by processes of both construction (how fast organisms grow and reproduce) and destruction (how fast reefs break down by mechanical...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 Reef Seafloor Erosion and Coastal Hazards
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.Measuring Coral Growth to Help Restore Reefs
It is critical to start measuring calcification rates in a systematic way now, particularly at subtropical latitudes where conditions fluctuate seasonally, so that we can understand how dynamic ocean conditions affect calcifying organisms today and predict possible changes in the future. We established a calcification monitoring network in the Florida Keys and have been measuring calcification... - Publications
Below are publications associated with this project.
Fidelity of the Sr/Ca proxy in recording ocean temperature in the western Atlantic coral Siderastrea siderea
Massive corals provide a useful archive of environmental variability, but careful testing of geochemical proxies in corals is necessary to validate the relationship between each proxy and environmental parameter throughout the full range of conditions experienced by the recording organisms. Here we use samples from a coral-growth study to test the hypothesis that Sr/Ca in the coral Siderastrea sidAuthorsIlsa B. Kuffner, Kelsey E. Roberts, Jennifer A. Flannery, Jennifer M. Morrison, Julie N. RicheyMulti-species coral Sr/Ca-based sea-surface temperature reconstruction using Orbicella faveolata and Siderastrea siderea from the Florida Straits
We present new, monthly-resolved Sr/Ca-based sea-surface temperature (SST) records from two species of massive coral, Orbicella faveolata and Siderastrea siderea, from the Dry Tortugas National Park, FL, USA (DTNP). We combine these new records with published data from three additional S. siderea coral colonies to generate a 278-year long multi-species stacked Sr/Ca-SST record from DTNP. The compoAuthorsJennifer A. Flannery, Julie N. Richey, Kaustubh Thirumalai, Richard Z. Poore, Kristine L. DeLongThe relationship between the ratio of strontium to calcium and sea-surface temperature in a modern Porites astreoides coral: Implications for using P. astreoides as a paleoclimate archive
An inverse relationship has been demonstrated between water temperature and the ratio of strontium to calcium (Sr/Ca) in coral aragonite for a number of Pacific species of the genus Porites. This empirically determined relationship has been used to reconstruct past sea-surface temperature (SST) from modern and Holocene age coral archives. A study was conducted to investigate this relationship forAuthorsTess E. Busch, Jennifer A. Flannery, Julie N. Richey, Anastasios StathakopoulosA reconstruction of sea surface temperature variability in the southeastern Gulf of Mexico from 1734 to 2008 C.E. using cross-dated Sr/Ca records from the coral Siderastrea siderea
This study uses skeletal variations in coral Sr/Ca from three Siderastrea siderea coral colonies within the Dry Tortugas National Park in the southeastern Gulf of Mexico (24°42′N, 82°48′W) to reconstruct monthly sea surface temperature (SST) variations from 1734 to 2008 Common Era (C.E.). Calibration and verification of the replicated coral Sr/Ca-SST reconstruction with local, regional, and historAuthorsKristine L. DeLong, Christopher R. Maupin, Jennifer A. Flannery, Terrence M. Quinn, CC ShenSr/Ca proxy sea-surface temperature reconstructions from modern and holocene Montastraea faveolata specimens from the Dry Tortugas National Park
Sr/Ca ratios from skeletal samples from two Montastraea faveolata corals (one modern, one Holocene, ~6 Ka) from the Dry Tortugas National Park were measured as a proxy for sea-surface temperature (SST). We sampled coral specimens with a computer-driven triaxial micromilling machine, which yielded an average of 15 homogenous samples per annual growth increment. We regressed Sr/Ca values from resultAuthorsJennifer A. Flannery, Richard Z. PooreLinear extension rates of massive corals from the Dry Tortugas National Park (DRTO), Florida
Colonies of three coral species, Montastraea faveolata, Diploria strigosa, and Siderastrea siderea, located in the Dry Tortugas National Park (DRTO), Florida, were sampled and analyzed to evaluate annual linear extension rates. Montastraea faveolata had the highest average linear extension and variability in (DRTO: C2 = 0.67 centimeters/year (cm yr-1) ± 0.04, B3 = 0.85 cm yr-1 ± 0.07), followed byAuthorsAdis Muslic, Jennifer A. Flannery, Christopher D. Reich, Daniel K. Umberger, Joseph M. Smoak, Richard Z. PooreHolocene core logs and site methods for modern reef and head-coral cores - Dry Tortugas National Park, Florida
The Dry Tortugas are a series of islands, banks, and channels on a carbonate platform off the west end of the Florida Keys. Antecedent topography of the Dry Tortugas reflects carbonate accumulations of the last interglacial (marine isotope substage 5e, ~ 125,000 years ago, ka) when sea level was ~ 6 to 7 meters (m) higher than present (Schrag and others, 2002). The substage 5e surface was subsequeAuthorsTodd D. Hickey, Christopher D. Reich, Kristine L. DeLong, Richard Z. Poore, John BrockSt. Petersburg Coastal and Marine Science Center's Core Archive Portal
This Web site contains information on rock cores archived at the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC). Archived cores consist of 3- to 4-inch-diameter coral cores, 1- to 2-inch-diameter rock cores, and a few unlabeled loose coral and rock samples. This document - and specifically the archive Web site portal - is intended to be a 'living' documentAuthorsChris Reich, Matt Streubert, Brendan Dwyer, Meg Godbout, Adis Muslic, Dan UmbergerHolocene core logs and site statistics for modern patch-reef cores: Biscayne National Park, Florida
The bedrock in Biscayne National Park (BNP), a 1,730-square kilometer (km2) region off southeast Florida, consists of Pleistocene (1.8 million years ago (Ma) to 10,000 years ago (ka)) and Holocene (10 ka to present) carbonate rocks (Enos and Perkins, 1977; Halley and others, 1997; Multer and others, 2002). Most of the surficial limestone in BNP, including the islands of the Florida Keys, was formeAuthorsChristopher D. Reich, T. Don Hickey, Kristine L. DeLong, Richard Z. Poore, John BrockCoral reefs, present and past, on the west Florida shelf and platform margin: Chapter 4
This paper summarizes the geomorphic variability of these different reef types, their geologic setting, and the present coral-reef biological community. The paper is organized along a virtual depth transect by presenting different reef settings and types starting from the shallower mid-shelf or mid-ramp setting, moving to the shelf edge, and then to the deeper upper slope.AuthorsAlbert C. Hine, Robert B. Halley, Stanley D. Locker, B. D. Jarrett, Walter C. Jaap, David J. Mallinson, Katherine T. Ciembronowicz, Nancy B. Ogden, Brian Donahue, David NaarPatch-reef morphology as a proxy for Holocene sea-level variability, Northern Florida Keys, USA
A portion of the northern Florida Keys reef tract was mapped with the NASA Experimental Advanced Airborne Research Lidar (EAARL) and the morphology of patch reefs was related to variations in Holocene sea level. Following creation of a lidar digital elevation model (DEM), geospatial analyses delineated morphologic attributes of 1,034 patch reefs (reef depth, basal area, height, volume, and topograAuthorsJ. C. Brock, M. Palaseanu-Lovejoy, C. W. Wright, A. NayegandhiUtility of shallow-water ATRIS images in defining biogeologic processes and self-similarity in skeletal scleractinia, Florida reefs
A recently developed remote-sensing instrument acquires high-quality digital photographs in shallow-marine settings within water depths of 15 m. The technology, known as the Along-Track Reef-Imaging System, provides remarkably clear, georeferenced imagery that allows visual interpretation of benthic class (substrates, organisms) for mapping coral reef habitats, as intended. Unforeseen, however, arAuthorsB. H. Lidz, J. C. Brock, D.B. Nagle - News
Below are news stories associated with this project.