Preliminary Comparison of Natural Versus
Model-Predicted Recovery of
Vessel-Generated Seagrass Injuries in
Florida Keys National Marine Sanctuary
A. V. Uhrin, M. S. Fonseca, and W. J. Kenworthy
NOAA/NOS Center for Coastal Fisheries and Habitat Research (CCFHR)
Each year, more than 500 motorized vessel groundings cause widespread damage to
seagrasses in Florida Keys National Marine Sanctuary (FKNMS). Under Section 312 of
the National Marine Sanctuaries Act (NMSA), any party responsible for the loss, injury,
or destruction of any Sanctuary resource, including seagrass, is liable to the United States
for response costs and resulting damages. As part of the damage assessment process, a
cellular automata model is utilized to forecast seagrass recovery rates. Field validation of
these forecasts was accomplished by comparing model-predicted percent recovery to that
which was observed to be occurring naturally for 30 documented vessel grounding sites.
Model recovery forecasts for both Thalassia testudinum and Syringodium filiforme
exceeded natural recovery estimates for 93.1% and 89.5% of the sites, respectively. For
Halodule wrightii, the number of over- and under-predictions by the model was similar.
However, where under-estimation occurred, it was often severe, reflecting the well-
known extraordinary growth potential of this opportunistic species. These preliminary
findings indicate that the recovery model is consistently generous to Responsible Parties
in that the model forecasts a much faster recovery than was observed to occur naturally,
particularly for T. testudinum, the dominant seagrass species in the region and the species
most often affected. Environmental setting (i.e., location, wave exposure) influences
local seagrass landscape pattern and may also play a role in the recovery dynamics for a
particular injury site. An examination of the relationship between selected environmental
factors and injury recovery dynamics is currently underway.
Keywords: Seagrass recovery, vessel groundings, seagrass disturbance, seagrass recovery model,
Florida Keys National Marine Sanctuary, Mini-312 Program
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