Geospatial video monitoring of nearshore benthic habitats of Biscayne Bay, Florida using the shallow-water positioning systems (SWaPS)

Lirman, Diego; Deangelo, Gregory; Brown, Alexandra

The nearshore habitats of Biscayne Bay, a shallow lagoon adjacent to the city of Miami, are heavily influenced by salinity fluctuations caused by freshwater discharges from canals but the benthic communities in these susceptible littoral habitats have been under-represented in existing monitoring programs due to the difficulties associated with boat access. In this project, we implemented a geospatial video survey technique, the Shallow-Water Positioning System (SWaPS), to monitor the abundance and distribution ofbenthic organisms in western Biscayne Bay. This system uses a GPS receiver attached to a video camera installed in a shallow-draft boat and each video frame recorded is stamped with position, date, depth, heading, and pitch and roll. The field surveys using SWaPS showed that species distributions are influenced by their respective tolerances to salinity patterns. Seagrass species with high tolerance for low salinity like Halodule wrightii, Ruppia maritima have high abundance only in areas influenced directly by canal discharges, while species with limited tolerance for low salinity like marine sponges are rare along nearshore habitats. The use of video surveys with a high spatial precision provides a rapid, cost-effective, and repeatable method to monitor marine benthic communities. The most attractive features of the this system are the ability to: 1) survey large areas rapidly without the need to deploy divers; and 2) return to precise locations without the need to establish permanent markers. Moreover, the digital video and still images collected with SWaPS are a valuable permanent visual archive that can provide the baseline information needed to evaluate long-term patterns of change in environments like Biscayne Bay that are subject to increasing pressure from human activities.