On Tue, 24 Feb 2009 13:33:16 -0600, thunder
wrote:

Yeah, I've seen quite a few grass flats with scars criss-crossing them.
One wouldn't think the damage would be all that severe, but I've read
that many sea grasses are already under considerable duress, and in some
cases, already endangered.

Once the grass is scarred it seems to change the whole ecology
underneath. On the flats the scar frequently creates a channel for
tidal run off and that tends to make it deeper over time and keep it
open. One thing that's being done in the Keys is to install public
moorings in areas where people frequently anchor for diving or
fishing. The new "screw pile" moorings cause very little bottom
disruption and anchor scarring is minimized.