Archive for Science
By Alisha A. Renfro, Ph.D., Staff Scientist, National Wildlife Federation
Worldwide, rising global temperature is a threat to coastal communities in the form of rising sea levels and stronger hurricanes. Last week, the Louisiana State Museum in New Orleans hosted a presentation by Virginia Burkett, Ph.D., Chief Scientist for Global Climate and Land Use Change at the United States Geological Survey. In Dr. Burkett’s presentation, “Climate Change and Sea Level Rise: Implications for New Orleans,” she discussed the science of climate change and the threats sea level rise present to the vulnerable low-lying landscape and communities of coastal Louisiana. Louisiana’s 2012 Coastal Master Plan acknowledges these threats and outlines a 50-year plan for protection and restoration that takes into account subsidence, sea level rise and increased storm frequency and intensity.
Global sea level rise is a consequence of water influx from melting glaciers and ice sheets and the expansion of ocean water as it is heated. During the 20th century, global sea level rose approximately eight inches, but satellite data indicates that the annual rate of sea level rise has almost doubled over the last 20 years. As the different processes that affect melting of large ice sheets are still the subject of intense scientific study, the range of predicted sea level rise in this century ranges from 0.6 to 6.6 feet, but the most likely range of sea level rise is between one and four feet.
While the predicted rate of global sea level rise is enough to cause concern for many coastal regions, in Louisiana, the threat is intensified as not only is sea level rising, but the land is also sinking. Subsidence can occur due to natural geological processes, such as dewatering and compaction of deposited river sediments over time, but it can also be increased by human actions, such as groundwater withdrawal and oil and gas extraction. Subsidence rates across Louisiana’s coast vary, but in many areas, the rate of subsidence far exceeds the global rate of sea level rise. The combination of global sea level rise and local subsidence means that the local sea level will rise sooner and higher in Louisiana than in most other places in the world.
At the conclusion of her talk, Dr. Burkett had a few recommendations for actions we here in Louisiana can take to adapt to sea level rise and increase the resiliency of our coastal communities and coastline. For coastal communities, elevating and flood-proofing infrastructure are important steps for adapting to the increased threat of inundation from sea level rise and hurricanes, but in some cases, retreat from low-lying coastal areas may be necessary.
We can better manage our coast by factoring our understanding of the natural processes and trends and by getting sediment from the Mississippi River into the wetlands. As one of the most vulnerable areas to sea level rise in the United States, coastal Louisiana will serve as the testing ground for scientific innovation and policy that will likely shape the response of coastal communities throughout the country to the threats of climate change and sea level rise.No Comments
Study demonstrates importance of sediment diversions for building land in the Mississippi River DeltaMarch 27, 2013 | Posted by Delta Dispatches in 2012 Coastal Master Plan, Diversions, Restoration Projects, Science
By Alisha A. Renfro, Ph.D., Staff Scientist, National Wildlife Federation
Last week, an independent scientific panel comprised of prominent scientists from throughout the U.S. released a report, “Mississippi River Freshwater Diversions in Southern Louisiana: Effects of Wetland Vegetation, Soils, and Elevation,” which examines some of the ecological effects of freshwater river diversions. The panel concluded that there is little evidence suggesting that the existing freshwater diversions in Louisiana have appreciably reversed the rate of land loss in the region, and that to reverse the land loss trend, significant inputs of sediment are needed. While most of the existing diversions in Louisiana were built to move fresh water only, many of the diversions included in Louisiana’s 2012 Coastal Master Plan focus on sediment capture and conveyance into coastal wetlands.
Freshwater diversions affect basins by reducing salinities. Extensive dredging of canals throughout the Mississippi River Delta’s wetlands has allowed for salt water from the gulf to intrude into wetlands adapted to lower salinity conditions, resulting in large areas of these wetlands dying and being converted to open water. Wetland vegetation is affected directly by the salinity of the water in wetland soil. High salt concentrations in the soil can affect vegetation by reducing the overall rate of photosynthesis, decreasing nutrient uptake and stunting growth rates. Consequently, the introduction of fresh water into wetland communities damaged by saltwater intrusion is vital in any restoration effort.
Freshwater diversions also increase the amount of nutrients introduced into the receiving basin. While increases in nutrient availability to wetland vegetation would presumably stimulate growth, scientific information collected in Louisiana marsh communities have exhibited varying results depending on plant species, nutrient concentrations and the abundance of different types of nutrients. Increasing the amount of nutrients may also alter the composition of the plant community, as some species of plants have a competitive advantage when it comes to nutrient uptake and growth.
River diversions can also have an influence on wetland elevation. In order for wetlands to persist over time, processes that increase the surface elevation of the wetlands must be equal to factors that increase the threat of submergence (e.g. sea level rise, storms). Diversions have the potential to promote an increase in the elevation of a wetland by adding mineral sediment to the surface and stimulating plant growth both above and below ground. However, the surface elevation of a wetland could decrease as nutrients become less scarce, as the abundance of vegetation roots decline and as an increase in the breakdown of belowground organic material by bacteria takes place. More scientific studies are needed to enhance our understanding of the relationship between marsh response and river input in order to better predict the net effect that sediment and freshwater diversions may have on different marsh types.
This scientific panel found that any freshwater diversion that does not transport a substantial sediment load is unlikely to reverse the current trend of wetland loss in Louisiana. The 2012 Coastal Master Plan recognizes and addresses this reality by focusing on large-scale diversions that would be capable of transporting significant amounts of river sediment into the nearby wetlands. In addition to shifting the focus of diversions from fresh water to sediment, the panel determined that a formal adaptive management scheme is needed for existing and planned diversions where the goals of the project are clear, the pre-diversion conditions of the affected area are well characterized, monitoring in the outfall area is done to measure the progress of the project in relation to its goals and a process exists to adjust the operation of the structure to increase the likelihood those goals are reached.
- Fact sheet: "Pulsed" land-building sediment diversions
- Mississippi River Freshwater Diversions in Southern Louisiana: Effects of Wetland Vegetation, Soils, and Elevation (Technical Panel from the Workshop on Response of Louisiana Marsh Soils and Vegetation to Diversions)
By Emily Guidry Schatzel, Communications Manager, National Wildlife Federation
Recent news reports suggest that the potential for compromise exists in the case of Mardi Gras Pass, the newest known distributary of the Mississippi River. The pass was discovered in 2012 when the river cut a channel through its bank in the Bohemia Spillway, a stretch without levees, giving an exciting and rare view at how a natural delta system operates.
While the pass promises ecological prosperity for the delta, the newly enlarged channel washed out the private road that one local oil company uses to access its facilities. The company has since applied for a permit to rebuild that road. Coastal restoration advocates believe that the current plan to rebuild will effectively close the Mardi Gras Pass and will eliminate encouraging ecological benefits that scientists from the Lake Pontchartrain Basin Foundation have been monitoring since the channel’s development.
This video further explains the debate over keeping the pass open, and alternatives for compromise. The key takeaway? Whether it be construction of a bridge, or another reasonable alternative that gives the oil company access while allowing Mother Nature to literally “run its course,” this is clearly an issue that requires the full attention of key decision-makers so that the best long-term solution is achieved.
As Dr. John Lopez, executive director of the Lake Pontchartrain Basin Foundation — the organization that discovered the pass in 2012 — said, “It’s the kind of thing that most scientists sit in their offices there, dreaming how it might happen. Here, you can actually see it.” Keeping Mardi Gras Pass open is important — it’s a chance for the river to reconnect with its wetlands, which is exactly what the river is designed to do.1 Comment
By Whit Remer, Policy Analyst, Environmental Defense Fund
The Gulf Coast Ecosystem Restoration Council recently released "The Path Forward to Restoring the Gulf Coast: A Proposed Comprehensive Plan." The RESTORE Act, signed into law in July, required the newly created Restoration Council to publish a Proposed Plan within six months of the legislation becoming law. Only six pages in length, the Path Forward provides a general framework for the Restoration Council to follow while developing their more robust Initial Comprehensive Plan, due out in July 2013. Moving forward, it is important that the Restoration Council create a Comprehensive Plan concentrated on restoring Gulf Coast ecosystems, which are the backbone of a healthy and thriving gulf economy.
Following the 2010 gulf oil disaster, Congress passed the RESTORE Act to ensure robust restoration of the Gulf Coast. Through the RESTORE Act, Congress developed a framework for federal and state officials to undertake comprehensive restoration. Congress provided money for restoration by ensuring at least 30 percent of funds under the RESTORE Act are dedicated to ecosystem projects. To oversee much of the restoration, the RESTORE Act establishes a highly experienced body of federal and state stakeholders, known at the Gulf Coast Ecosystem Restoration Council. Finally, the law requires the Restoration Council to develop a scientifically-based Comprehensive Plan to guide ecosystem restoration projects to implementation. The “Path Forward” document is a first step to building a plan for ecosystem restoration.
As expected, and required by law, the Path Forward builds on the work and recommendations of the Gulf Coast Ecosystem Restoration Task Force, which was led by the Environmental Protection Agency. The Task Force strategy had four overarching goals: habitat restoration, restore water quality, replenish marine resources and enhance community resilience. The newly released Path Forward adds a fifth goal of revitalizing the gulf economy. Moving forward, it is important for the Restoration Council to ensure that funds dedicated to the Comprehensive Plan are used solely for ecosystem restoration projects. After all, numerous studies have shown that ecosystem restoration supports economic restoration, including healthy tourism and fishing industries. New jobs created by the ecosystem restoration projects help protect existing infrastructure, rebuild critical wetlands, and create a new export industry focused on coastal and delta restoration.
We are excited about the Restoration Council’s commitment to long-term recovery in the gulf. In the Path Forward, the Restoration Council has reaffirmed their plans to invest in “specific actions, projects, and programs that can be carried out in the near-term to help ensure on-the-ground results to restore the overall health of the ecosystem.” By incorporating the best available science and adapting the Comprehensive Plan over time to incorporate new science, the plan can advance innovative ecosystem restoration solutions, like freshwater sediment diversions.
We look forward to the next draft of the Comprehensive Plan due out sometime before July.No Comments
By Alisha A. Renfro, Ph.D., Staff Scientist, National Wildlife Federation
On April 20, 2010, a blowout of BP’s Macondo well, just 50 miles off the coast of Louisiana, began the largest marine oil spill in U.S. history. For more than 80 days, oil spewed from the well into the deep and dark waters of the Gulf of Mexico, quickly spreading to mid-depths and to the surface. While this disaster resulted in the mobilization of an unprecedented amount of resources to address the environmental emergency, in many cases, the experience and response methods used in other oil spills were found to be ineffective or impossible to apply in this case. An article in the current issue of the Proceedings of the National Academy of Sciences of the United States of America, “Science in support of the Deepwater Horizon response,” examines the federal agency coordination and response to this spill as well as the many valuable lessons learned that should be applied to future events.
The size and complexity of the BP oil spill presented unprecedented challenges to federal and academic scientists. For the response and cleanup efforts, scientists needed real-time scientific data, from determining the flow rate of oil from the well to tracking and predicting where oil would surface to assessing the effects the oil and dispersant had on species and habitats throughout the gulf ecosystem. This spill also pushed scientists to use existing scientific methods in fresh ways and to develop new methods to help answer important questions. In addition, the National Science Foundation awarded more than $10 million through their Rapid Response program to scientific research that focused on various aspects of the oil spill.
This tragic event highlighted several important science priorities that are crucial for future oil spill response preparedness, including gathering adequate baseline data in at-risk regions, filling in information gaps about the biological effects of oil, collecting data to understand the cost of an oil spill to the impacted region and the nation and conducting more research on the impacts of dispersants on different types of species at various life stages. In the case of the BP oil disaster, scientists are now trying to answer these questions in hindsight, which can lead to further damage to the environment, the health of the workers involved in the cleanup efforts and the recovery of the ecosystem.
As oil and gas exploration pushes into deeper and deeper waters, it is imperative that we take steps to safeguard the ecosystems at risk. While everyone hopes that an event like the gulf oil spill doesn't happen again, we need to not only be prepared for the possibility of it happening again, but we also need to be prepared to respond to it better. More than 1,000 days since the start of the spill, the gulf is still waiting to be made whole.
- Lubchenco J, McNutt M, Dreyfus G, et al., Science in support of the Deepwater Horizon response. Proceedings of the National Academy of Sciences of the United States of America, 2012-20221.
By Shannon Hood, Environmental Defense Fund
Terrestrial carbon sequestration is the process by which atmospheric carbon dioxide is taken up by plants through photosynthesis and stored as carbon in biomass and soil. During the process of photosynthesis, plants take carbon dioxide from the atmosphere, coupled with sunlight and water, and turn it into sugar and oxygen, allowing them to act as long-term storage facilities for carbon (“carbon sinks”). Some carbon is re-emitted during the process of respiration, but overall, vegetated areas act as net carbon storage facilities. Utilizing vegetated areas as sinks for carbon allows carbon emissions from other sources (fossil fuel emissions, deforestation, etc.) to be offset. The value of forested lands has been documented for carbon sequestration (e.g., “REDD-Avoiding Planned Deforestation” and “Afforestation and Reforestation of Degraded Lands”), however, until now, the ability of wetlands to capture and store blue carbon hasn’t been formally recognized or quantifiable.
Tierra Resources LLC, an environmental consulting firm based in New Orleans, has developed the first American Carbon Registry-certified methodology for creating carbon offset credits for wetland restoration activities. (In a follow-up post, we will provide information on the methodology and test site). The methodology provides a calculation for determining the number of carbon credits that may be obtained from a wide variety of wetland restoration projects. Never before had wetlands entered the arena for carbon credits, but the potential for credits to be obtained from their restoration is tremendous!
Biologically, wetlands are some of the most highly productive ecosystems in the world, with high rates of photosynthesis. Higher rates of photosynthesis lead to greater carbon capture and storage by trees, grasses and other plants. In addition, wetlands soils are largely anaerobic, meaning that incorporated carbon decomposes slowly and can be stored for long periods of time.
Tierra Resources estimates that if 25 percent of the four million acres of Mississippi River Delta wetlands that are eligible under this methodology are selected for restoration through carbon sequestration, between $5 and $15 billion may be generated over the next 40 years. This creates an additional source of funding for wetlands restoration and adds yet another ecosystem service to the many already provided by the Mississippi River Delta.No Comments
By Alisha A. Renfro, Ph.D., Staff Scientist, National Wildlife Federation
This year, drought conditions throughout most of the country have left the Mississippi River flowing at a near all-time low. This is a stark comparison to 2011, when heavy rains and a large snowmelt in the spring sent record levels of water and sediment flowing down the river. At the Old River Control Structure north of Baton Rouge, the flow of the river is split, with 70 percent continuing down the Mississippi to the Bird’s Foot delta, and the remaining 30 percent flowing down the Atchafalaya River. During the 2011 flood, the flood protection levees and the opening of the Morganza and Bonnet Carré spillways successfully shunted water safely past the high population centers in the region. However, this event was a missed opportunity to capitalize on the influx of fresh water and sediment and to reconnect the river with sediment-starved wetlands of Louisiana.
In a recent study published in Nature Geoscience, research led by Federico Falcini, Ph.D. examined the link between the historic 2011 river flood and sediment accumulation in nearby wetlands. Their analysis suggested that the natural dynamics of the coastal system coupled with man-made alterations to the river system influenced the amount of sediment deposited in the wetlands. This work shows that under river flood conditions, diverting the flow of the river into shallow basins adjacent to the river could contribute significantly to sediment deposition in the wetlands and therefore contribute to wetland growth.
In the study, the sediment plumes of the Mississippi and Atchafalaya Rivers were tracked using satellite imagery from the 2011 flood event to understand where the sediment went once it exited these rivers. The Mississippi’s sediment plume exited the river in focused jets of sediment-laden water due to the confinement of much of the river’s flow between artificial levees. This plume moved past the coastal current and into the deeper waters of the Gulf of Mexico, limiting the amount of sediment that could be deposited in the near-shore area and adjacent wetlands. In contrast, the Atchafalaya’s sediment plume exited the river and moved along a broad, near-shore area, mixing with waters from the Gulf of Mexico and creating conditions that were likely to favor sediment deposition.
A comparison of sediment accumulation during the 2011 flood in nearby marshes shows a trend that corresponds to the difference in behavior of the two river plumes. Sediment accumulation was highest at marsh sites near the Atchafalaya River, which supports the idea that its sediment plume spreading out over a large area in relatively shallow water, promoting increased sedimentation in the region. Sediment accumulation in wetlands near the mouth of the Mississippi River was substantial, but significantly lower than near the Atchafalaya. While the Mississippi River carried a larger sediment load during the 2011 flood event, much of the sediment was lost to the deeper waters of the gulf.
Louisiana’s 2012 Coastal Master Plan identifies several sediment diversions that are key to restoring the important coastal Louisiana landscape. The success of these diversions will depend on a variety of factors, including location and operation. However, this new research confirms that fine sediments introduced into shallow water can substantially contribute to sediment accumulation in wetlands. In order to restore the rapidly deteriorating wetlands of coastal Louisiana, it is critical to reintroduce the sediment that once built this productive region.2 Comments
By Alisha Renfro, Ph.D., Staff Scientist, National Wildlife Federation
In the aftermath of the BP oil disaster, President Obama created the Gulf Coast Ecosystem Restoration Task Force through an executive order in October 2010. The mission of this Environmental Protection Agency-led group was to develop a long-term, holistic and science-based ecosystem restoration plan for the Gulf Coast.
Included in this effort was the Science Coordination Team which involved more than 70 scientists from federal and state agencies who provided scientific input for the development of the strategy document. While the final Gulf of Mexico Regional Ecosystem Restoration Strategy was released in December 2011, the Science Coordination Team realized there was also a need to develop a science program to ensure that both focused and ecosystem-wide science would be available to implement and maintain the Gulf Coast restoration projects. The science team produced a report in April 2012 titled “Gulf of Mexico Ecosystem Science Assessment and Needs,” which identified current conditions in the gulf and specified actions that need to be taken to meet the goals set for a healthier ecosystem.
The qualifiers for the recovery of the Gulf of Mexico ecosystem are:
- Coastal wetland and barrier shoreline habitats are healthy and resilient.
- Fisheries are healthy, diverse, and sustainable.
- Coastal communities are adaptable and resilient.
- A more sustainable storm buffer exists.
- Inland habitats, watersheds, and offshore waters are healthy and well managed.
The coastal habitats of the Gulf of Mexico are some of the most productive ecosystems on earth. However, there has been an overall decline in health of these ecosystems as wetlands have been lost, barrier islands have eroded, and water and sediment quality has declined, which has increased stressors on commercially-important species and other organisms. As miles of the Gulf Coast’s protective wetlands and shorelines have been lost due to natural disasters and other events, including the BP oil spill and several hurricanes, the vulnerability of the people who call the region home has increased.
To address these changes, the science team recommended a variety of actions, including identifying historic changes in land use and shoreline changes; determining the sediment, water and nutrient resources needed to support sustainable habitats; and increasing the understanding of the relationships between different types of gulf habitats. Additionally, long-term, continuous scientific data, analysis, and interpretation were identified as critical for informing the design, construction, and operation of restoration projects. They were also considered key in developing modeling tools, methods, and protocols for undertaking ecosystem-level restoration planning and assessing restoration success.
Increasing the health of the surrounding ecosystem will also help improve the resiliency of coastal communities. To directly address risk reduction for communities, the science team suggested holding workshops and training opportunities to bring together local community planners, emergency managers and building code officials to learn about the surrounding environment and how to build more resilient coastal communities.
In September 2012, the duties and responsibilities of the Task Force were transitioned to the Gulf Coast Ecosystem Restoration Council. That month, President Obama issued an Executive Order recognizing the importance of the Gulf Coast as a national treasure and acknowledging the successful completion of the Task Force and its strategy document. The Executive Order transferred the Task Force’s duties to the new Restoration Council. The Council, established by the RESTORE Act, will build on the work of the Task Force, identifying projects and programs that would help restore and protect natural resources and ecosystems of the Gulf Coast with funding from the RESTORE Act’s Gulf Coast Restoration Trust Fund. With a strategy and source of funding in place, recovery and restoration of the Gulf Coast, including the Mississippi River Delta, moves one step closer to becoming a reality.No Comments
This story was originally published by the National Wildlife Federation.
By Craig Guillot, National Wildlife Federation
When Hurricane Isaac struck Louisiana on the seven-year anniversary of Hurricane Katrina, its winds and tidal surge caused four deaths and at least $1.5 billion in insured damages. For many residents around the Mississippi River Delta, Isaac brought back memories of two recent disasters to hit the coast — Katrina and the 2010 Gulf oil disaster. Before the storm even hit land, residents in some coastal communities noticed a rise in the number of tar balls washing ashore. Officials later discovered moderate amounts of tar balls and weathered oil in coastal Louisiana, Mississippi and Alabama.
Experts say scenes like this could be normal for decades to come and that Louisiana’s coast will require constant monitoring and a long-term plan for restoration. Despite advertising campaigns to the contrary, the region is still reeling from the Gulf oil disaster more than two years after the blow out of BP’s Macondo well.
Tar balls and oil reappears in the Mississippi River Delta
Even before Hurricane Isaac hit the coast, residents in communities from Grand Isle, La., to as far east as Gulf Shores, Ala., started to report an increase in tar balls washing ashore as the Gulf began to churn. Tar balls, sheen and various remnants of weathered oil were found following the storm in many of those areas including the pristine shorelines of Ship Island in Mississippi.
A National Wildlife Federation (NWF) team surveyed the waters and beaches near Port Fourchon, Elmer’s Island and Grand Isle on September 6 to survey the waters and beaches. While they did not find any evidence of significant oiling, they did find moderate amounts of tar balls on the beaches in Grand Isle. Tar balls have been a reality on Louisiana's coast for decades but Grand Isle residents say what was left on the beaches after Isaac was "a lot more than normal."
NWF Staff Scientist Alisha Renfro, Ph.D., said a number of tropical storms and weather events have washed up tar balls since the start of the 2010 disaster.
“They continue to wash up because there’s a lot of weathered oil still out there, either just offshore or just beneath the surface of the sand,” Renfro said.
NWF also made a trip out to Myrtle Grove, La., on September 7 to survey the damage that Isaac inflicted on the marsh. The eye of the storm first made landfall near the mouth of the Mississippi River and passed over some of the state's most fragile marshes before making a second landfall near Port Fourchon.
David Muth, Louisiana state director for NWF, said the team found evidence of localized marsh destruction. On his survey, Muth noticed hundreds of large chunks of marsh that had broken away and been deposited in open water.
“Marsh break-up occurred in areas that have a history of rapid marsh loss in Louisiana, near Myrtle Grove. Healthier marshes to the south showed no signs of break-up. The findings illustrate the importance of quickly building the authorized Myrtle Grove Sediment Diversion, which will build new marsh in this vital area.”
The NWF team also found three oiled pelicans near Myrtle Grove. A number of media outlets reported oiled birds and wildlife following the storm. While there is no connection between these findings and the Macondo disaster, Muth said, “This is further evidence that we have not yet completely learned the lessons of the Gulf oil disaster.
"Oil could be here for decades."
Even 23 years after the Exxon-Valdez spill in Prince William Sound, Alaska, oil can still be found beneath the surface. Biologists say that "sub-lethal" effects to fisheries could linger in the Gulf of Mexico for years to come.
"It will probably be an issue for a long time, especially as many people conjecture that there are still tar mats laying on the bottom that you can't easily clean up," Muth said.
In April 2012, two years after oil started pouring into the Gulf, an NWF team found heavy oil still sitting just beneath the surface on small islands in Barataria Bay and Bay Jimmy. On one island, the oil was so abundant that it oozed to the surface under each foot step. Renfro said while oil may remain below the surface during the winter, it can emerge in the spring and summer when the heat softens it up and liquefies it. Many biologists believe that reappearing oil could be an annual occurrence in the summer months.
If there’s any good news, it’s that when oil comes to the surface, sunlight and weathering can help further break it down.
“Photo-oxidation from the sunlight helps break down that material even more. It also helps reveal it so that cleanup crews can get it. Hopefully we’ll have less and less over time,” Renfro said.
Last week, Louisiana State University ran lab tests for the Louisiana Department of Wildlife and Fisheries and determined that the oil found on Grand Isle and Elmer's Island matched the footprint for the oil spilled from BP's Macondo well. BP later confirmed that the oil was from the well and that they would dispatch workers to clean it up.
Ed Overton, Ph.D., professor emeritus with the Department of Environmental Sciences at Louisiana State University, said that while oil is still out there, it is hard to tell exactly how much. Overton did say that storms can serve as “Mother Nature’s hurricane” in helping break down the oil. He believes that oil will degrade faster on the Gulf Coast than it did in Prince William Sound because of the geography of the shore.
“Our shoreline erodes and moves around more quickly. The problem with sandy beaches is that once it gets buried, you just don’t know where it is. We’ll likely see it for years but not at the level we saw in 2010,” Overton said.
Mississippi River Delta wetlands remain in a precarious state
Biologists and coastal restoration advocates say while the oil is an issue, it is only one part of a number of problems eating away at Louisiana’s wetlands. Oil has attacked the roots of plants and contributed to the death of marsh grass and mangroves but the encasement of the Mississippi River and saltwater intrusion has had a destructive impact for decades. In some areas of the marsh, the oil appears to have been the final straw.
Renfro also surveyed the Mississippi River by air on September 7 and saw heavily damaged patches of marsh between Belle Chase and Point a la Hache. She and Muth said there were clear differences in how untouched marshes fared compared to those that were heavily oiled during the summer of 2010.
“Pelican Island doesn’t look good at all. The mangrove has just been all brown and dead. It saw heavy oiling in 2010,” Muth said.
While marshes have always endured the winds and surges of hurricanes, Muth said he’s seen clear differences in how a healthy marsh can recover quickly. Further south in “healthier” areas of marsh, Muth said some parts looked almost invigorated by the storm where natural processes can deposit new layers of clay and sediment.
Renfro said the Wax Lake Delta is a clear example of how a thriving marsh can recover from a storm. After Hurricane Rita struck the area in 2005, damage to these wetlands was observed in the aftermath of the storm, but there was not a significant lasting impact. The Wax Lake Delta has been a rare success story in coastal restoration because it is fed sediment by the Atchafalaya River.
“The steady supply of mineral-rich sediments from the river help make these wetlands more resilient and allow them to recover quickly when damaged,” Renfro said.
NWF’s Greater New Orleans Program Manager Amanda Moore said it all underlines why the Gulf Coast needs a long-term comprehensive strategy for coastal restoration. NWF was instrumental in helping create and push for the passage of the RESTORE Act, a bill that ensures 80 percent of the fines and penalties from the Gulf oil disaster will be dedicated to Gulf Coast restoration.
Moore said its passage has been a monumental victory for the coast and that funding in the near future should help move along big coastal restoration projects. Ongoing monitoring of the impacts of the Gulf oil disaster will be needed to ensure a sound recovery.
“We knew that when the disaster happened, we'd be dealing with this for years to come. We need to keep vigilant and watching it because we could be dealing with this for a long time,” Moore said.No Comments
By Meg Sutton, Environmental Defense Fund
Oyster reefs in coastal estuaries around the globe have been degraded for the past 100-200 years due to a combination of overfishing, harmful dredging practices, decreasing water quality, sedimentation and oyster diseases.1 Many formerly productive reefs are now functionally extinct, and it is estimated that 85 percent of reefs have been lost globally.2 The majority of commercial oysters are currently sourced from only five eco-regions in the world, concentrated on the east coast of North America and the northern Gulf of Mexico.2 In Louisiana, restoration of oyster reefs has been proposed to both mitigate the decline in stocks and to secure a number of co-benefits which oysters provide. Such restoration has an associated cost which has some asking: How much is an oyster worth?
Restoration of oyster reefs in the gulf would impart several benefits to the region including increases in oyster and fish stocks, improved water quality, erosion control, storm attenuation and economic stimulus for local businesses. Each of these benefits has an associated economic value and should be factored into the decision to bring oyster reef restoration to scale.
The most readily apparent economic benefit of oyster reef restoration is an increase in, or maintenance of, primary oyster productivity. Louisiana is the leading oyster producing state in the U.S., supporting an oyster industry that generates $35 million in dockside value annually.3 Additionally, oyster reefs serve as refuge and feeding ground for many estuarine species including fish, mobile crustaceans and invertebrates. This ecosystem benefit is especially pertinent along the Louisiana coast, where oyster reefs are the primary three-dimensional habitats available. In Louisiana, 23 percent of annual marine fishing occurs over oyster beds, and these areas provide approximately $2 million (2003 dollars) in fisheries value annually for coastal Louisiana.4
Oysters are filter feeders, and this filtration notably reduces the turbidity and nitrogen loading of their surrounding water. Reduction of turbidity — the removal of suspended solids — has been shown to have a significant recreational value for boating and beach swimming. The willingness to pay for reduction in bacteria and oil, as well as improvement in water color for beach goers, was estimated to be $23.39 per person per year.5 In a study of the Choptank River in Maryland, the economic value of the nitrogen removed by an oyster over a ten-year interval was found to be greater than the dockside value of the oyster.6 In a separate analysis, an acre of healthy oyster reef was estimated to yield $3,000 in de-nitrification value annually.7
Additionally, the three-dimensional oyster reef structure attenuates wave energy, which can reduce erosion rates. Oyster reefs are generally understood to dampen wave energy by creating frictional energy between their rough outer surfaces and the wave. The associated economic value of wave attenuation is hard to determine, as it varies based on location. One factor to consider, however, is that the Gulf of Mexico has over 8,000 miles of shoreline that are at risk for erosion.8 Erosion rates and risk of flooding due to storm surge will continue to increase over time with global climate change, environmental degradation and subsidence of the area. If we choose to armor these shorelines, the current option is to install a bulkhead. Bulkheads can cost up to $1 million per mile, while oyster cultch placement — a common method for oyster reef restoration — can be completed for one-third of the cost.8
The industrial and commercial activity that would be generated by large-scale gulf oyster restoration will additionally boost the economy in the Gulf Coast and provide new job opportunities in the gulf and in 17 other states.9 Such restoration efforts would generally benefit small businesses, creating opportunities for local residents to both build new business and contribute to the sustainability of their region.
Restoration of oyster reefs may be necessary to maintain oyster landings in Louisiana, and it would also contribute to the sustainability of the region through ecological co-benefits, shoreline protection and economic stimulus. While these benefits may be difficult to generalize to a per-oyster dollar value, it is clear that the overwhelming co-benefits of oyster reef restoration in Louisiana should be considered in conjunction with the total cost of restoration.
1 Grabowski, J.H. & Peterson, C.H. Restoring oyster reefs to recover ecosystem services. Theoretical Ecology Series 281-298 (Elsevier Academic Press: Burlington, MA, 2007).
2 Beck, M.W. et al. Oyster Reefs at Risk and Recommendations for Conservation, Restoration, and Management. BioScience 61, 107-116 (2011).
3 Louisiana Department of Wildlife and Fisheries. Oyster Stock Assessment Report. (Baton Rouge, LA, 2010).
4 Henderson, J. & O’Neil, J. Economic Values Associated with Construction of Oyster Reefs by the Corps of Engineers. United States Army C (2003).
5 Freeman, A.M.I. The Benefits of Water Quality Improvements for Marine Recreation : A Review of the Empirical Evidence. 10, 385-406 (1995).
6 Newell, R., Fisher, T., Holyoke, R. & Cornwell, J. Influence of Eastern Oysters on Nitrogen and Phosphorus Regeneration in Chesapeake Bay, USA. The comparative roles of Suspension Feeders in Ecosystems 47, 93-120 (2005).
7 Piehler, M.F. & Smyth, A.R. Habitat-specific distinctions in estuarine denitrification affect both ecosystem function and services. Ecosphere 2, (2011).
8 National Fish and Wildlife Federation. Toward a Healthy Gulf of Mexico: A Coordinated Strategy for Oyster Restoration in the Gulf. 1-6 (2012).
9 Duke Center on Globalization, Governance & Competitiveness. Stokes, S., Wunderink, S., Lowe, M. & Gereffi, G. Restoring Gulf Oyster Reefs: Opportunities for Innovation (2012).