Seagrass Habitat Characterization in Estuarine Waters of the Jacques Cousteau National Estuarine Research Reserve Using Underwater Videographic Imaging Techniques

Abstract

A benthic habitat assessment study conducted in the Barnegat Bay-Little Egg Harbor Estuary from June to November 2006 reveals that boat-based videographic imaging is comparable to in situ diver observations for determining the occurrence and percent cover of seagrasses in actively growing beds. A Seaviewer Sea Drop camera and recorder unit deployed along 12 transects in the estuary generated 331 images of seagrass habitat during the study period. A comparison of video still images with data derived from diver observations indicates consistent results in terms of the presence/absence and percent cover of seagrass on the estuarine floor throughout the seagrass growing season. Plots of the percent cover of seagrass recorded by the camera system vs. in situ diver observations reveal a high correlation for the June–July, August–September, and October–November sampling periods (R2 = 0.936, 0823, and 0.894, respectively) as well as for the entire June–November sampling period (R2 = 0.888). A kappa statistic calculated for the presence/absence of seagrass in the estuary (0.83) reflects a nearly perfect level of agreement between the two methods (camera and diver) of data collection. In addition to generating rapid databases, digital underwater video imaging requires less field time than the use of divers and other traditional field monitoring methods. Digital videographic files can also be post-processed, geolocated using a global positioning system, analyzed by multiple investigators, and stored for later analysis, thereby offering several other advantages over traditional in situ monitoring techniques in shallow estuarine systems.