Discover Seagrass Over Time

While we are fortunate in having a series of seagrass surveys dating back over thirty years, the great difference in mapping methods and technologies make a rigorous comparison of the surveys problematic. The earliest 1970’s survey relied on aerial photography complemented by float plane-assisted field checking. The 1980’s survey relied on a boat-based systematic sampling of a grid at every one-quarter mile interval while the 1990’s survey was a boat-based survey that traced the outer boundaries of individual seagrass beds using a Global Positioning System. The most recent survey in 2003 was accomplished using digital camera imagery and advanced computer analysis techniques.

As a scientist one must always question the data and try to make sure that you are comparing “apples to apples.” In this case, some of the differences we see between the surveys represent a “real” change in the amount and distribution of seagrass and some represent an “artifact” of the technique used. While these surveys are not directly comparable (comparing apples to oranges), these surveys do allow us to examine general temporal (across time) and spatial (across space) trends in seagrass distributions in Barnegat Bay. The more recent 1990’s and 2000’s surveys suggest that there has been loss of seagrasses in the deeper waters of the bay, resulting in the contraction of the beds to the shallower subtidal flats (< 1 m depth), as well as a decline of the size of seagrass beds in the northern part of the Bay. While we can not conclusively establish that there has been a major dieback and loss of seagrass area, there is reason for concern over the status of seagrass beds in Barnegat Bay.