Ecological effects of Gulf Coast hurricanes

Hurricane Katrina made landfall August 29, 2005 becoming the costliest ($75 billion) and one of the deadliest (nearly 2,000 human lives lost) hurricanes in U.S. history. With the nation still reeling from Katrina, Hurricane Rita hit on September 24, 2005, causing $10 billion in damage but taking a far less direct toll on human lives. The duo's ecological consequences were also considerable: storm surges flooded coastal areas. Powerful winds felled forests in south Louisiana and Mississippi, havens for wildlife and migratory birds. Saltwater and polluted floodwaters from New Orleans surged into Lake Pontchartrain. Taking stock nearly a year later, experts from the Gulf Coast region will address the storms' ecological consequences and will offer insights on how ecological knowledge can help mitigate damage from future hurricanes.

“Not only is the City of New Orleans built on reclaimed wetlands that have subsided by up to 5 meters, over 25 percent of coastal wetlands disappeared in the 20th century,” says John Day (Louisiana State University). Day, one of the symposia's presenters, argues that serious wetland restoration plans must close or restrict the Mississippi River Gulf Outlet, a canal that contributed to the flooding of New Orleans and that disconnects the river from its delta plain. Wetlands help stem storm surges and diffuse powerful winds.

Complementing Day's argument, Paul Keddy (Southeastern Louisiana University) believes residents in the Gulf Coast states will have to decide if they want “business as usual” or a dramatic change in the way people accept the limitations and realities of dynamic coastal areas. During his presentation, Keddy will lay out what he sees as the connections between hurricanes, human irrationality, and Gulf Coast ecosystems. “From the American dust bowl to the collapse of the Canadian cod fishery, people have chosen development trajectories that are catastrophic in the longer term,” he says.

Gary Shaffer (Southeastern Louisiana University) will suggest some concrete wetlands restoration steps that he believes will need to go hand-in-hand with human-made flood control barriers. “Bald cypress – water tupelo swamps are particularly effective at dampening forward progress of both floodwaters and winds,” he notes. Shaffer believes that cypress and tupelo seedlings could achieve 10 meter heights within a single decade and serve as major storm damage reduction agents.

Looking specifically at Louisiana's Lake Pontchartrain, Carlton Dufrechou's (Lake Pontchartrain Basin Foundation, a non-profit organization dedicated to restoring and preserving the Lake Pontchartrain Basin) presentation will include post-storm satellite imagery that suggests that Hurricane Katrina may have destroyed over 60 square miles of the lake's wetlands in a mere 24 hour period. “As more coastal areas disappear, residents in the region become more vulnerable to the effects of tropical storms and hurricanes,” says Dufrechou. On a brighter note, however, the lake's water quality appears to have recovered to pre-Katrina conditions, in spite of being the recipient of nearly nine billion gallons of highly contaminated water pumped out of New Orleans and into the lake.