A science-based seagrass survey window for coastal construction project planning in Florida

Abstract

A variety of construction activities occur in or near estuarine and coastal waters of Florida within habitats that may support seagrass. Resource managers have a need for a science-based seagrass survey window for Florida to ensure that habitats are adequately mapped and characterized prior to authorizing the destruction or modification of the habitat. The development of a survey window requires a balance between physical factors that maximize the ability to detect seagrass during sampling (essentially water clarity) and the time of year that supports peak biomass and distribution. Of the seven seagrass species found in Florida, two species exhibit greater seasonality: Halophila decipiens and Halodule wrightii. Several publications were synthesized that refer to the seasonality of seagrass. Based on this review and consultation with leading seagrass scientists, surveys for these seagrass species should occur June 1 through September 30. Results from surveys conducted outside this window will require careful evaluation given the likelihood that seagrass distribution or extent is underrepresented. This recommendation differs from but is not in conflict with recommendations from NMFS Protected Resources Division for Johnson's seagrass, Halophila johnsonni, which exhibits a life history that makes year-round sampling less problematic than it is for Halophila decipiens and Halodule wrightii. Because Halophila decipiens and Halodule wrightii are within the range of Halophila johnsonii, conducting surveys within the June 1 to September 30 window could eliminate the need for multiple surveys.