Recently, seagrass recovery has stagnated in several areas of Tampa Bay, despite ambient water quality and light availability conditions that appear adequate to support continued seagrass expansion. For example, the deep edges of the H. wrightii meadows in southeastern Hillsborough Bay and in eastern Middle Tampa Bay were estimated to receive an average 44 and 57% of the incident light, respectively. These light levels are considerably greater than the 20.5% light target adopted by the TBEP, however, no significant expansion of these meadows into deeper water has occurred over the last five years.

Many factors may limit seagrass expansion in Tampa Bay in addition to water quality. Lewis et al. (1985) discussed the importance of an offshore unvegetated sand bar, that separates the main seagrass meadow from the open bay waters, to protect the seagrass meadow by reducing wave impacts from storms and ship traffic. Destabilization and the ultimate loss of the bar may result in the shoreward migration of the seagrass meadow. However, studies examining the dynamics of the shallow sand bars and their interaction with the development of seagrass meadows are lacking for Tampa Bay.

Additional elevation measurements are recommended to learn more about the seagrass depth distribution and the dynamics of the shallow sand bars in Tampa Bay. The GPS carrier-phase processing technique could be used to accurately and quickly determine the transect depth profiles of the 62 bay-wide seagrass monitoring transects (see Avery and Johansson 2001). Further, the depth distribution of the different seagrass species found on each transect could easily be determined during the profile measurements.

Periodically conducted seagrass and transect elevation measurements will provide important information to complement the biennial high altitude aerial seagrass photography conducted by Southwest Florida Water Management District and the yearly cooperative Tampa Bay seagrass transect monitoring program. Combined, the three programs would become a powerful tool for evaluating the progress of the Tampa Bay water quality and seagrass restoration effort.