The depth at the edge of the grass bed is called the ecological compensation
depth (ECD), because it is the depth below which the carbon balance for the
entire canopy becomes negative, and hence, unsustainable. In the Indian River
Lagoon (Florida, U.S.A.), the ECD for Halodule wrightii and for Syringodium
filiforme appeared to be the depth to which 23–37% of surface irradiance penetrated
(Kenworthy, 1992).