If the brown tide persists for a long time, it could kill off the sea grasses and change the Laguna Madre from a sea grass ecosystem to a phytoplankton ecosystem.
(the brown tide; persists; T:for a long time) (it; could kill off; the sea grasses) (it; change; the Laguna Madre; from a sea grass ecosystem; to a phytoplankton ecosystem)
the brown tide it it
persists could kill off change
T:for a long time
the sea grasses
the Laguna Madre from a sea grass ecosystem to a phytoplankton ecosystem