Principal Investigators: Dr. Thomas N. Lee, Dr. Su Sponaugle, Dr Villy Kourafalou
Participating Institutions: University of Miami
Funding: EPA (grant R8280200), NSF (grant OCE 9986359)
Project Dates: April 2000 - December 2004
The National Center for Caribbean Coral Reef Research (NCORE) was established at the University of Miami's Rosenstiel School of Marine and Atmospheric Sciences (RSMAS) to provide an organization to facilitate interdisciplinary, science-based, ecosystem process studies of coral reefs, with the aim of better understanding the natural and human influences that have controlled their past growth histories and present health. One of the first projects to be undertaken by NCORE was a study of nutrient dynamics of coral reefs in the Florida Keys.
Several sites in Pennekamp Park were identified for the initial study. Research efforts included a measurement program to quantify the nutrient inputs to the coral reefs. The necessary physical oceanographic measurements consisted of continuous time series measurements of currents and temperature from seven moorings which were deployed June 2000 through November 2003 from the R/V Walton Smith.
Hydrographic (CTD) measurements were also made and water samples were collected for nutrient analysis on bimonthly cruises of the R/V Walton Smith. The cruises were also used to maintain the moored instrumentation by diver recovery of the instruments, cleaning, recovery of all time series data to a laptop computer, replacement of batteries and any other parts that appeared defective.
To identify and describe oceanographic processes influencing recruitment in the upper Florida Keys off Key Largo, a moored array of current and temperature loggers was maintained across the shelf at the study site for the period: June 2000 to Oct. 2003 (Figs. i and 2). In this study, we used data from bottom temperature loggers (made by TSKA) positioned across the outer reef crest at depths of 9.8, 7.0, 4.0, and 5.6 m, and from mooring C, which was positioned just seaward of the reef crest at the 24 m isobath where Florida Current (FC) influences are expected to be significant. Mooring C was equipped with Sontek Argonaut-MD single point measuring acoustic current meters and temperature loggers at depths of 4 and 21 m; the data were recorded every 10 minutes in UTC. Mean hourly wind data were obtained from the NOAA-NDBC SEAKEYS/C-MAN Station MLRF1 at nearby Molasses Reef. To help identify and track the movement of frontal eddies and meanders into and through the Straits of Florida, satellite AVHRR sea surface temperature (SST) images from the study period were downloaded from the Ocean Remote Sensing Group website at John Hokins University Applied Physics Lab (http://fermi.jhuapl.edu/avhrr/).
Current and wind data were converted into an along-shelf (v-component) and cross-shelf (u-component) coordinate system, rotated 40º clockwise from true north, with v positive downstream (northeastward) toward 40º and u positive offshore toward 130º. The raw, unfiltered (10 minute) current and temperature records were used to examine high-frequency physical processes. High-frequency decreases in bottom water temperatures at semi-diurnal tidal periods indicate the onshore movement of internal tidal bores. In order to examine low-frequency physical processes, the raw data were filtered with a 3-hour low-pass filter to apply some initial smoothing to the data, and then a 40-hour low-pass filter was applied to remove tidal and higher frequency fluctuations, resulting in subtidal time series. These filtered data were used to identify low-frequency events such as the passage of frontal eddies. Mesoscale eddies pass along the Florida Keys reef tract every few months on their downstream march through the Straits of Florida. Their cyclonic circulation entrains warm-water streamers from the FC and causes reversals in the typical downstream alongshore currents. Thus the passage of eddies through the coastal waters is indicated by a sharp increase in near-bottom water temperature occurring simultaneously with a current reversal at subtidal periods.
Moorings A, B and C were bottom-mounted, moorings with temperature loggers and current measuring devices
Moorings labeled TL1 through TL4 where bottom mounted temperature moorings. During this project, five, CTD stations were added along the cross section of the deployed mooring array during the Florida Bay project cruises. The Florida Bay project, which coincided with the same time period as this project, also had standard stations to the northeast (downstream) and southwest (upstream) of the deployed NCORE moorings
|Temp Logger 4
|Temp Logger 3
|Temp Logger 2
|Temp Logger 1