LSU Science & Technology | Barrier Island Breakdown

Ship Shoal to the Rescue?

Greg Stone's research team is using various types of instrumentation to take measurements and collect data on and near Ship Shoal. By studying the large sand body, the researchers can predict whether removing some of the sand would be harmful to the habitat around Ship Shoal.

Those South Louisiana residents who have experienced major hurricanes, such as Betsy, Andrew, and Georges, tend to view those storms as measuring sticks for other hurricanes. But LSU researchers say that if a storm like Betsy, which hit New Orleans in 1965, hit today, the damage would be far worse than it was back then, primarily because of the extensive loss of the coast's wetlands and barrier islands to erosion and sinking.

According to Greg Stone of the Department of Oceanography and Coastal Sciences, Louisiana is experiencing the highest rate of coastal erosion in America, losing about 100 yards of land every 30 minutes. That's a football field every half-hour.

In addition, barrier islands and beaches are eroding at rates in excess of 20 feet per year in some locations, Stone said.

Losing those islands is like losing the state's "first line of defense" against hurricanes and tropical and winter storms, Stone said. The barrier islands protect the coastline by breaking down waves and storm surges before they hit the coast and move onshore toward the wetlands.

But LSU is fighting to save the coastline and preserve the all-important barrier islands and wetlands. And a large body of sand known as Ship Shoal, located about 10 miles offshore, may play a key role.

Stone, who is the James P. Morgan Distinguished Professor and faculty member in the Department of Oceanography and Coastal Sciences and director of LSU's Coastal Studies Institute, is working with two other LSU researchers to study the feasibility of mining sand from Ship Shoal and pumping it onto existing barrier islands to stabilize them.

Before the idea can be considered, however, some major questions about Ship Shoal have to be answered, such as:

Will removing sand from Ship Shoal disturb the bottom-dwelling invertebrates, shrimp, and speckled trout that inhabit the waters around the sand body? Because shrimp feed on invertebrates, and speckled trout feed on shrimp, any disturbance of Ship Shoal could disrupt the food chain and possibly alter the habitat around Ship Shoal. That habitat is crucial to Louisiana's shrimping industry.
What role does Ship Shoal play in breaking down wave energy? If Ship Shoal is mitigating wave conditions offshore and serving almost the same function as a barrier island, will removing the sand make Louisiana's erosion problem worse by causing bigger waves to hit the barrier islands and coastline during storms?
Could the sand be removed without disturbing the oil and gas pipelines and rigs that exist on and around Ship Shoal? The oil and gas industry is vital to Louisiana's economy and is part of the reason Louisiana's erosion problem affects the entire nation.

Louisiana's barrier islands, like the one shown here, are the state's first line of defense against hurricanes and storm surge, but they are eroding at an alarming rate. LSU researchers are working to restore those islands and help protect the coastline.

To answer the questions about the habitat around Ship Shoal, Stone brought two of his colleagues in on the project, Associate Professor Richard Condrey of LSU's Department of Oceanography and Coastal Sciences and Coastal Fisheries Institute, and George C. Kent Endowed Professor John Fleeger of LSU's Department of Biological Sciences. Condrey will study the Ship Shoal habitat in relation to shrimp, speckled trout, and macroscopic invertebrates, and Fleeger will study it in relation to microscopic invertebrates.

Meanwhile, with the assistance of the Coastal Studies Institute's Field Support Group, Stone will soon deploy a variety of instruments on Ship Shoal to measure waves, currents, sediment transport, and other variables.

Precise measurements of what happens on and around Ship Shoal will enable Stone to run accurate computer models that will predict what will happen if Ship Shoal is altered.

By working together, the three researchers should be able to predict any adverse effects of mining Ship Shoal. If they discover that mining it will be harmful, then they'll be able to rule out the possibility of using Ship Shoal to help restore the coast.

Their study, funded by a $1.2 million grant from the Mineral Management Service (MMS) and the Louisiana Department of Natural Resources, and coordinated with LSU's Coastal Marine Institute, is the first impact study for MMS that will examine what an environmental change might do to a major fishery habitat.

Click image for larger view.

Stone said they are studying Ship Shoal for two major reasons: Its sand is high-quality and coarser than the sand on the barrier islands, therefore, it would last longer on the barrier islands and reduce wave energy more effectively than finer sand; and, since Ship Shoal is located in close proximity to the barrier islands of south-central Louisiana, there would be fewer costs associated with getting the sand to the coast than if sand from farther offshore was used.

Stone said he is hopeful that current wetland restoration projects will help the coast's situation, but he believes the barrier islands need immediate attention. "We can pump sediment into the wetlands and marshes all we want, but if we don't enhance the barrier islands, we're only doing half the job," Stone said.

He believes this study of Ship Shoal is a step in the right direction. And while pumping new sand onto the barrier islands is only a temporary fix, Stone says it's still essential. "The laws of physics show that we can't stop coastal erosion, but what we can do is buy ourselves some time," he said. "At the rate we're losing land, preserving the coastline for two or three decades is really critical."

Contact Kristine Calongne | LSU University Relations
Highlights Team
Spring 2005