Georgia Southern University and Gray’s Reef NMS researchers release current-tracing dye and drifters into Altamaha River outflow

With funding provided by the Georgia Department of Natural Resources and vessel support from Gray’s Reef National Marine Sanctuary, researchers from Georgia Southern University released 50 gallons of fluorescent red dye (rhodamine WT) into the Altamaha River outflow during the week of May 12-16, 2014. The plume of dye was monitored visually and with instrumentation as it flowed from the release point (just south of Wolf Island) along the Georgia coast and offshore. Tracking the path of the dye will provide estimates of the extent to which the Altamaha River delivers dissolved contaminants and nutrients north and south along the Georgia coast and to hard-bottom reefs, such as Gray’s Reef National Marine Sanctuary, occurring up to 20 miles offshore.
The research team visually monitored the floating dye for the first eight to nine hours after the release and then relied on instruments, called fluorometers, programmed to scan for the presence of rhodamine WT in the water every minute of the day for two weeks. These fluorometers were positioned at four artificial reefs managed by Georgia DNR (reefs A, SFC, J-Y, and CAT), as well as Gray’s Reef to create an arc of detection points.

Marked with yellow crab-pot buoys and clearly labeled, these fluorometers are easy to spot. If sighted, please do not damage or remove them.

GR Drifter 1 wIn addition to releasing the dye, the investigators deployed up to four satellite-enabled drifters that will provide information on how larger materials, such as dead stalks of marsh grass, may disperse after being exported from the Altamaha River estuary.The drifters are constructed from basic materials found in local hardware stores such as bamboo poles, drop cloths, hose clamps, and nylon cord. Data obtained from the drifter paths will be made available to local school teachers for use in the classroom. As with the buoys, these drifters will be clearly labeled so please do not remove them if spotted offshore. Alternatively, please contact the investigators if a drifter is found on shore.

For additional information, contact Georgia Southern University’s Dr. Daniel Gleason (912-478-5957), Dr. Risa Cohen (912-478-1228), or Gray’s Reef Communications and Outreach Coordinator Amy Rath (amy.rath@noaa.gov; 912-598-2397).

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