| 1 |
Godcharles 1971 |
Tampa Bay, Florida, USA |
Not given |
Open sand, sand with seagrass, and sand with algae |
Water
jets penetrate to 45 cm, create trenches 15-45 cm deep; uprooted vegetation;
decreased proportion of fine sediment in some dredge tracks. |
Trenches
lasted longer (up to 86 days) in grass beds, filled in immediately in open
sand; most sediments hardened within 1 mo, some spots still soft 500 days
after dredging; sediment composition returned to normal after 1 yr, but
seagrass still had not recovered; new algal growth after 86 days, complete
after a year. |
SCUBA
observations and sediment sampling before and after experimental escalator
dredging in undisturbed sand, seagrass, and algae bottom habitats; recovery
monitored for 16+ mo. |
| 2 |
Orth et al. 1998 |
Chincoteague Bay, Virginia, USA |
Not given |
Seagrass beds |
Circular
“scars” left by dredges; loss of grass and large holes in dredge track. |
No
revegetation 3 yr after disturbance; recovery estimated to take at least 5 yr
in lightly disturbed areas, longer in heavily disturbed areas. |
Field
observations of commercial escalator dredging effects over a 3-yr period. |