Abstract: A portable ammonium analyzer was developed and used to measure in situ ammonium in the marine environment. The analyzer incorporates an improved LED photodiode-based fluorescence detector (LPFD). This system is more sensitive and considerably smaller than previous systems and incorporates a pre-filtering subsystem enabling measurements in turbid, sediment-laden waters. Over the typical range for ammonium in marine waters (0-10 µM), the response is linear (r2 = 0.9930) with a limit of detection (S/N ratio >3) of 10 nM. The working range for marine waters is 0.05-10 µM. Repeatability is 0.3% (n = 10) at an ammonium level of 2 µM. Results from automated operation in 15 min cycles over 16 days had good overall precision (RSD = 3%, n = 660). The system was field tested at three shallow South Florida sites. Diurnal cycles and possibly a tidal influence were expressed in the concentration variability observed.
Abstract:
An acoustic Doppler current profiler was installed on the south side of the Port Everglades Inlet to measure the velocity of the water flow at levels starting near the surface and reaching down to near the channel bottom. The system was built using a commercial, horizontal-looking ADCP deployed in a hybrid manner to measure the vertical velocity structure. This system was calibrated so that its velocity measurements could estimate the mean channel velocity at specific depth layers by repeatedly transecting a vessel-mounted, down-looking ADCP across the channel at the location of the fixed system. The channel cross-sectional area at the location of the fixed system was measured, and a pressure sensor on the fixed system allowed the cross section of the channel to be estimated at the time of each velocity measurement. From the area and mean channel velocity measurements, an estimate of the volume transport per unit of time (Q) in a surface and deep layer was made. By integrating the Q measurements over a tidal phase, measurements of total volume transport per tidal phase in the surface and bottom layers were made. These volume estimates will be used to estimate the total seaward flux of certain substances measured by the Florida International University group during the study. Using an independent data set, the dispersion of materials advected seaward from the inlet into the coastal ocean was estimated.
Abstract: Over the last ten years several wireless architectures have been developed for transmitting meteorological and oceanographic data (in real-time or near real-time) from coral reef ecosystems in Florida, the Caribbean, Saipan, and Australia. These architectures facilitate establishing trends in environmental parameters and aid in ecosystem modeling and ecological forecasting. Here, existing architectures, as well as those currently in development, are described, incorporating use of Geostationary Operational Environmental Satellites, radio transceivers, wireless digital cellular modems, mobile wireless hotspots, and Android phones. Each architecture is reviewed for advantages and disadvantages, along with some examples of deployments. These summaries provide reef managers and scientists with a suite of options for monitoring, allowing the selection of the most appropriate architecture for the particular needs and capacities of each coral reef location.
Abstract: The Integrated Coral Observing Network (ICON) program has constructed and installed a series of Coral Reef Early Warning System (CREWS) stations which provide a wealth of high-quality meteorological and oceanographic data in near real-time. CREWS stations date back to 2001 with the deployment of an early buoy-type design in the Bahamas. Beginning in 2002, the program shifted to a pylon-type design which was reengineered in 2005, resulting in the modern CREWS stations found in the Bahamas, Puerto Rico, the U.S. Virgin Islands and Jamaica. The CREWS instrumentation architecture described herein has evolved over time into a robust package that, combined with a regimen of regular instrument cleaning and recalibration, has yielded a continuous, long-term, high-quality dataset from these harsh marine environments.