ACQUISITION OF ACOUSTIC DATA IN HIGHLY ENERGETIC, TIDE-DOMINATED COASTAL LAGOONS OFF CAPE COD, MA: MAPPING THE SEAFLOOR SWATH BY SWATH

The glacial bluffs of Cape Cod provide a uniquely sediment-rich environment resulting in the formation of complex barrier systems. Energetic nearshore environments undergo spatial and temporal variations in response to wind, tide and anthropogenic-driven dynamics. Storms are particular drivers of coastal change, often disrupting navigation and impacting vulnerable ecosystems such as eelgrass beds, oyster reefs and saltwater marshes. Acoustic mapping of coastal nearshore environments is integral to understanding the processes that drive coastal change, and provides empirical data to managers for rigorous, science-based guidance. Mapping highly energetic coastal lagoons where a large percentage of the survey area is intertidal, poses challenges that can vary dramatically from traditional vessel-based surveying, and often requires “out of the box” flexibility and some measure of finesse. To safely and efficiently map these systems, modification of vessels and proper configuration of equipment is required. Surveying tide-dominant systems require careful planning, allowing for short survey days and sudden changes in sea conditions. Between 2014 – 2018, the Center for Coastal Studies mapped 4 tide-dominated coastal lagoons in Barnstable County, MA, using a phase measuring sidescan sonar. The results of these surveys will be discussed as well as insights into improving data acquisition and post-processing methods.