Development and Implementation of Sargassum Early Advisory System (SEAS): Phase One By Brandon N. Hill Ocean and Coastal Resources bhill8901@yahoo.com Robert K. Webster Ph.D. Candidate, Marine Sciences Department captrwebster@aol.com Texas A & M University at Galveston P.O. Box 1675 Galveston, Texas 77553

Abstract: Sargassum is a crucial aspect of many oceanic and coastal environments. However, it can inundate a coast if the conditions permit excessive growth and landings. In nature this is not a detriment to the beaches, but actually serves to reduce erosion and provide nutrients. When beaches are relied upon to support the tourism industry abnormally excessive Sargassum landings can become an impediment. This creates a struggle between the environmental good of the beach and the economic good of the tourism industry. The Sargassum Early Advisory System (SEAS) Phase One focuses on increasing the efficiency of the current beach management practices. Phase One begins with the effort to employ NASA Landsat images as early warning devices of Sargassum's impending landfall. Oceanic currents as well as coastal wind patterns are hypothesized to be the primary drivers of Sargassum. The Hybrid Coordinate Ocean Model (HYCOM) as well as the Texas Automated Buoy System (TABS), Weatherbuoy, and beach cameras are used to receive real time data as well as future predictions to allow for the creation of accurate macroalgae forecasts. Landsat imagery has a sufficient resolution that slicks created by the Sargassum's disruption of the water surface can be differentiated. The Landsat's RGB array allows it to identify large Sargassum mats by a distinct green glow. The SEAS Team has created a 555 km X 516 km swath of monitoring that provides two to three week notices of eminent Sargasssum landfall. The remote sensing data is crosschecked with ground-truthing via mounted beach cameras and boating contacts. The SEAS Team creates advisories that are sent out to local beach managers and other stakeholders. These advisories allow for the beach managers to more efficiently allocate resources. If Sargassum is not observed in the Landsat images then beach managers are able to scale back the workforce and equipment committed to removing the Sargassum from the beach. If an excess of Sargassum is projected to make landfall the beach managers are better equipped to service the beaches before the arrival of tourists. This added efficiency saves money and time that otherwise would be left up to guesswork. The SEAS Phase One has increased the knowledge of Sargassum locomotion via currents. The Landsat imagery supports the hypothesis that wind can be a major contributor to Sargassum's movements. Evidence of Langmuir Circulation is found in the images, implying that wind plays a larger role than originally thought. The average direction and speed of Sargassum can be deduced by using certain methods of creating a sum total of movement by considering wind and ocean current velocity and direction. The proximity of the Landsat images and their frequency of recurrence allow for the progress of the Sargassum slicks to be tracked. Given this and the other methods that the SEAS Team has employed allows for extreme accuracy in predictions. With an accuracy rate of 98% the SEAS Team has created a monitoring system that is a utility for those dealing with Sargassum.