Archive for Science
By Alisha Renfro, National Wildlife Federation & Jacques Hebert, National Audubon Society
Last week while some people on the Gulf Coast were in the thick of celebrating Mardi Gras, more than 1000 scientists, including those from the Restore the Mississippi River Delta campaign, met in Houston, Texas, to attend the third-annual Gulf of Mexico Oil Spill and Ecosystem Science Conference. The four-day conference, which included a mix of keynotes and oral and poster presentations, aimed to share scientific information and forward scientific understanding of the Gulf of Mexico ecosystem and particularly the impact of oil pollutants on this fragile ecosystem. Nearly five years since the BP oil spill, the takeaway is clear: The effects of the oil spill on the Gulf ecosystem are far-reaching, ongoing and significant.
Here are three key highlights from last week’s conference:
- The impact is far-reaching: Research ranging from the deep sea to Gulf shoreline estuaries has documented significant impacts of the oil spill on ecosystems and on different animal and plant life.
- The impact is ongoing: Recent research has found a large amount of the oil discharged during the spill can still be found in offshore sediments. Storms, like Hurricane Isaac in 2012, redistribute oil into previously unoiled marshes and wash sandy tar balls onto beaches.
- The impact is significant: The rate of marsh shoreline erosion increased with oiling and continued impacts on marshes have been documented at least four years after the spill.
And for more, don’t miss some of the media coverage that came out of the conference:
- Los Angeles Times: “BP cherry-picks study to dodge blame for massive deaths of gulf dolphins”
- Houston Chronicle: “Studies: BP spill reduced Gulf life”
- Houston Public Media: “Houston Conference Highlights Scientific Research On Deepwater Oil Spill Damage”
Want to learn about efforts to provide meaningful restoration in the ongoing wake of the BP oil spill? Visit mississippiriverdelta.org, like us on Facebook, and follow us on Twitter. You can also share this post with your network using the following tweet:
- 5 years later, major oil spill science conference tells us BP effects are evident and ongoing: http://www.mississippiriverdelta.org/blog/2015/02/26/five-years-later-scientists-gather-to-assess-ongoing-impact-of-bp-oil-spill/ #GulfScienceConference
Press Statement + Interview Opportunities Available
Emily Guidry Schatzel, National Wildlife Federation, 225.253.9781, email@example.com
Elizabeth Van Cleve, Environmental Defense Fund, 202.553.2543, firstname.lastname@example.org
Lauren Bourg, National Audubon Society, 225.776.9838, email@example.com
Final Phase of BP Oil Spill Trial to Begin Next Week
BP must be held fully accountable for its role in nation’s largest oil disaster
(New Orleans – January 15, 2015) On Tuesday, January 20, 2015, the third and final phase of the BP oil spill civil trial will begin in New Orleans. This concluding portion of the trial will determine how much BP will be required to pay in Clean Water Act fines for its role in the 2010 Gulf oil disaster.
National and local conservation organizations committed to Mississippi River Delta and Gulf Coast restoration – Environmental Defense Fund, National Wildlife Federation, National Audubon Society and the Lake Pontchartrain Basin Foundation – issued the following statement in advance of Tuesday’s proceedings:
“Nearly five years after the oil disaster, the people and wildlife of the Gulf Coast still wait for justice. For 87 days, BP dumped more than 200 million gallons of oil into our Gulf, contaminating our marshes and beaches and jeopardizing wildlife ranging from brown pelicans to sperm whales. But the oil giant has yet to take full responsibility. BP has dragged out litigation in the courts, challenging every decision only to have each decision against them confirmed by higher courts.
“Despite claims that it would ‘make it right’ in the Gulf, BP has, for the past five years, waged a public relations war focused on blaming everyone else and denying sound scientific research showing ongoing impacts from the oil disaster. The effects of the oil spill are far from over and may not be fully known for years, or even decades, to come.
“Now the court has the opportunity and responsibility to make it right, to hold BP fully accountable for the damage done to the Gulf and to assign the maximum penalty to BP for its gross negligence. The outcome from this decision must send a clear and powerful signal to every other operator in the Gulf: deep-sea drilling is risky business, and they must protect their employees, our communities and our ecosystems. BP chose not to do that, so they deserve to pay the maximum fines allowed by law.
“Through the RESTORE Act of 2012, Congress paved the way for the Gulf’s recovery by ensuring that 80 percent of the Clean Water Act fines BP will pay will be reinvested into Gulf Coast restoration. But that restoration can’t begin until this case is resolved and the legal wrangling ends – and BP remains the principle barrier to much-needed funding going to vital restoration projects.
“Holding BP fully accountable for the 2010 Gulf oil disaster is the fair and right thing to do for the Gulf’s ecosystems and economies. We are hoping, after five long years, that justice is close. The Gulf has waited long enough.”
Interview Opportunities: Interview opportunities are available with experts in science, policy, wildlife and restoration issues from our national and local conservation organizations.
Mississippi River Delta Restoration Experts:
David Muth, Director for Mississippi River Delta Restoration, National Wildlife Federation
Douglas J. Meffert, D. Env., MBA, Executive Director, National Audubon Society (Audubon Louisiana)
Steve Cochran, Director for Mississippi River Delta Restoration, Environmental Defense Fund
John A. Lopez, Ph.D., Coastal Scientist, Lake Pontchartrain Basin Foundation
Alisha Renfro, Ph.D., Coastal Scientist, Mississippi River Delta Restoration, National Wildlife Federation
Natalie Peyronnin, Director of Science Policy, Mississippi River Delta Restoration, Environmental Defense Fund
Courtney Taylor, Policy Director, Ecosystems Program, Environmental Defense Fund
Since the BP oil disaster began nearly five years ago, ongoing findings deliver truths omitted by BP’s ads: the oil disaster’s negative effects are increasingly clear, present and far from resolved. Over the past year alone, new research has surfaced:
- An October 2014 study showed that the Gulf oil disaster left an “oily bathtub ring” the size of Rhode Island on the sea floor.
- A study by the National Oceanic and Atmospheric Administration (NOAA) detailed how exposure to BP oil can lead to abnormalities including irregular heartbeats and heart attacks in Atlantic bluefin tuna and amberjack.
- A NOAA study revealed that dolphins exposed to BP oil had increased health problems, including adrenal problems, severe lung disease and reproductive issues.
- A study in the Proceedings of the National Academy of Sciences definitively linked a community of damaged deep water corals near the Macondo well to the BP oil spill.
- A Louisiana State University researcher found that the BP oil spill is still killing Louisiana coastal insects.
- Visible tar balls and tar mats continue to surface, including a 40,000-pound tar mat discovered off the coast of a Louisiana barrier island in June 2013, three years after the start of the oil spill.
- An infographic depicts ongoing impacts of the Gulf oil disaster.
By Matt Phillips, National Wildlife Federation
The 2010 BP Deepwater Horizon oil disaster spilled nearly 200 million gallons of oil into the Gulf of Mexico. Oil coated the shore, covering hundreds of miles of coastline, including some of Louisiana’s coastal wetlands. Scientists have spent the years since the spill assessing its continuing impacts on Gulf wildlife and ecosystems. And next Tuesday in New Orleans, Phase III of the BP oil spill trial will start in New Orleans.
In a recent study, “Physiological relationship between oil tolerance and flooding tolerance in marsh plants,” Keri L. Caudle and Brian R. Maricle of Fort Hays State University in Kansas studied how oil affects plant health. Studies have demonstrated that oil can poison plants, and toxic chemicals in oil can prevent photosynthesis – the process by which plants convert sunlight to food. Since all Gulf Coast wildlife, including birds, turtles, dolphins and insects, ultimately rely on plants for food and shelter, the effects of oil on plant life could impact the entire Gulf Coast ecosystem.
Besides a general toxic effect, relatively little is known about how oil impacts plant health. However, substantial research has assessed how plants deal with flooding. The authors of this study hypothesized that a plant’s response to flooding might be similar to its response to oil. In both situations, plants have a harder time absorbing oxygen from their surroundings. Oxygen is critical to a plant’s survival: Plants breathe similarly to humans at times, absorbing oxygen and exhaling carbon dioxide. If oil seeps into the soil, it could cover the plant’s roots, preventing them from absorbing oxygen.
The authors wanted to determine if oil harmed plants by preventing oxygen absorption or by poisoning them. To do so, they labeled nine species of plants as either flooding tolerant, moderately flooding tolerant or flooding sensitive. Because flooding prevents plants from absorbing oxygen from soil, flooding tolerance was an appropriate stand-in for oil tolerance. The researchers reasoned that if oil’s effects primarily prevented plants from getting oxygen, plants would have to breathe without taking in oxygen.
Plants are able to breathe without oxygen temporarily and produce a certain chemical compound in their roots when doing so. Therefore, the researchers measured whether this chemical was being produced to determine if the plants were still breathing but forgoing oxygen. If the effects of oil were instead due to toxic effects, then the plants would be less able to photosynthesize because their cells would be poisoned and unable to function properly.
The experimenters observed three important results. They found that flooding-sensitive plant species were breathing without oxygen, suggesting that they were struggling to absorb it from the soil. They also observed that flooding-tolerant species were not having trouble absorbing oxygen, suggesting that their tolerance to flooding afforded them a higher tolerance to oil. Third, they discovered that, regardless of tolerance to flooding, plants exposed to oil were photosynthesizing less than under normal conditions. The researchers determined that the toxic effects of the oil were interrupting the photosynthetic process.
The study concluded that oil affected plants most harmfully by preventing oxygen absorption, rather than through its toxic properties. Flooding-tolerant plants were better able to withstand the effects of oil, and continue absorbing oxygen, whereas flooding-sensitive plants had a harder time. They also recognized that across the board, oil proved toxic to plants. Oil tolerance followed flooding tolerance, but the toxic effects of the oil were still present across all species.
Plants are the foundation of the Gulf Coast ecosystem. Discovering the effects of oil on plant health is critical to understanding the full effects of the BP oil spill on Gulf Coast wildlife, as wildlife depend on plants for food and habitat. With this study, we have another piece of the puzzle.No Comments
By Theryn Henkel, Ph.D., Lake Pontchartrain Basin Foundation
The Coastal Sustainability Program at the Lake Pontchartrain Basin Foundation (LPBF) recently released an article titled “Examination of Deltaic Processes of Mississippi River Outlets–Caernarvon Delta and Bohemia Spillway in Southeastern Louisiana” in the Gulf Coastal Association of Geological Societies Journal. The article details work that LPBF has done investigating the development of the Caernarvon Delta and operation of the Bohemia Spillway, both located in Plaquemines Parish, La.
Natural land-building deltaic processes of the Mississippi River Delta have been severely limited by artificial river levees, which prevent water and sediment from flowing over the banks during spring floods. To counteract the effects of severing the connection between the river and the delta, focus has been placed on reconnecting the river to the surrounding wetlands by the creation of artificial outlets, also called diversions.
The Caernarvon Freshwater Diversion was designed to deliver up to 8,000 cubic feet per second (cfs) of water from the Mississippi River. For reference, a flow rate of 8,000 cfs could fill up an Olympic-size swimming pool in 11 seconds or the Superdome in 4.5 hours. The Mississippi River also contains sediment that is carried along with the fresh water through the Caernarvon Diversion into the adjacent wetlands or open water, where it can nourish the wetlands and/or build land.
LPBF collects data on the turbidity, or cloudiness, of the water diverted through the diversion. Through established equations, the cloudiness of the water can be related to sediment load or the amount of sediment carried in the water. From this, it was calculated that the total amount of sediment carried into the wetlands and open waters areas from 2009 to 2012 was 264,000 cubic yards, or a volume equal to 81 swimming pools. Due to other considerations, the diversion is not always operated when the sediment load in the river is high and therefore does not maximize potential sediment capture. Despite this variability in operation of the diversion – and the fact that the Caernarvon Diversion was built to minimize sediment capture, as it was built solely for salinity control, not land building – there actually has been enough sediment diverted by the Caernarvon Diversion to build a new delta. Total wetland growth of the delta in the open water area receiving diverted water from 1998 to 2011 was 600 acres. This new wetland area is lush and thriving with a variety of plant species (trees and herbaceous) growing, and alligators, birds and insects abound.
The Bohemia Spillway is an 11-mile stretch along the east side of Mississippi River south of New Orleans where the federal protection levees were removed. It was created in 1926 by the removal of existing artificial river levees, thereby allowing river water to flow over the banks and into the adjacent wetlands when the river was high. This overflowing process is how the river would have operated historically.
In 2011, the Mississippi River watershed experienced an historic flood which provided an ideal opportunity to investigate and study how the spillway operates. When the river overflows its banks, if brings fresh water, nutrients and sediment to the wetlands. This cannot happen when the connection is cut off by levees. The severing of the connection of the river to the wetlands is one of the contributing factors to the high rates of land loss rates experienced by southeast Louisiana.
Current land loss rates in the Bohemia Spillway are negligible, perhaps due to receiving inputs of fresh water, nutrients and sediment during high river events since 1926. We have not observed delta formation in the Bohemia Spillway, as we did at the Caernarvon Diversion, but we have observed the infilling of defunct navigation and oil and gas canals as they slowly convert back to land.
In many parts of Louisiana’s coast, man-made canals often contribute to increased land loss. Poorly maintained canals erode and become wider, and salt water is conveyed through the canals into adjacent fresh marshes, killing plants and converting land to open water. Therefore, seeing canals infilling and low rates of land loss in the Bohemia Spillway indicates that the restoration of somewhat normal processes, by reconnecting the river to the wetlands since 1926, has had a positive effect on the area.
For both Bohemia Spillway and the Caernarvon Diversion, there are clearly benefits to sustaining or increasing wetland areas. However, the two outlets also provide a contrast in the future possibilities. Precisely replicating the Bohemia Spillway by levee removal is generally not feasible because of the ongoing need for protection from river floods. However, a controlled diversion built and operated to more efficiently capture and deliver sediment in ways that emulate more natural processes, such as in the Bohemia Spillway, may hold great promise for coastal restoration, rather than the obsolete design and operational goals of a diversion such as Caernarvon.No Comments
By Alisha Renfro, National Wildlife Federation
“Oysters are the most tender and delicate of all seafoods. They stay in bed all day and night. They never work or take exercise, are stupendous drinkers, and wait for their meals to come to them.” – Hector Bolitho
Oysters are remarkable organisms. Not only are they delicious, but each oyster can filter up to 50 gallons of water per day, which provides food for the oyster and improves local water quality. A collection of oysters form an oyster reef, which can provide food and habitat for a wide variety of fish and birds. In addition to these benefits, oyster reefs can also be an important tool for coastal restoration.
Oyster barrier reef restoration can reduce the erosion and retreat of nearby shorelines. An alternative to rocks in some areas of coastal Louisiana, oyster reef restoration can be a low maintenance project, as reefs can build themselves vertically over time, helping them keep pace with rising sea levels.
The benefits of oyster reef restoration can be great, but are all those benefits present as soon as the reef restoration project is finished or do they develop over time? A study published this year in Ecological Engineering, “Temporal variation in development of ecosystem services from oyster reef restoration,” examines the development of oyster reef benefits over time, including improved water quality, stabilization of nearby shorelines and use as fish and bird habitat.
In the study, led by Megan La Peyre, researchers built six experimental oyster reef projects along the shoreline of Sister Lake in Terrebonne Parish, La. The oyster reefs were created using shell material. The researchers found that:
- Reefs were populated by oysters and other filter feeding organisms that provided water filtration benefits within the first year of post-project construction and continued for the duration of the study.
- Shoreline stabilization benefits provided by the restored reef to nearby marshes varied with results suggesting that shoreline stabilization benefits only occurred during periods of high winds and more powerful waves.
- Created oyster reefs immediately provided habitat and had increases in the abundance of fish species associated with them. This remained consistent throughout the study.
The results of this study suggest that oyster restoration projects can provide multiple benefits to the ecosystem that surrounds them fairly quickly after their construction, but that their ability to stabilize nearby shorelines may be limited in areas where waves are small but persistent. However, the researchers in the study suggest that modifications to the design and footprint of oyster reef restoration projects exposed to low energy wave may increase the shoreline stabilization benefits and should be explored further.
Oyster barrier reef restoration projects are an important component in our arsenal of coastal restoration tools. Prominently featured in Louisiana’s 2012 Coastal Master Plan, this project type can have multiple benefits under the right conditions. However, like all types of restoration projects, there are factors that can limit project success. Oyster reef restoration projects depend on the recruitment and survival of oysters, which flourish under very specific conditions. Water that is too cold, too fresh, too salty or doesn’t have enough oxygen can limit the success of the project – if not dooming it to complete failure.
No one type of restoration project is the cure-all for combatting the rapid loss of land in coastal Louisiana. Instead, we need to use a combination of science-based projects in our restoration toolbox to staunch the rapid loss of our coast and build a more sustainable future.No Comments
This post originally appeared on Environmental Defense Fund's EDF Voices blog.
By Estelle Robichaux, Environmental Defense Fund
Nine years ago, as Hurricane Katrina gathered strength in the Gulf of Mexico, I called my grandmother and namesake to wish her happy 84th birthday – and to urge her to leave her home on Bayou Lafourche until the storm passed.
It would take several more days before I heard my mother’s voice over the phone and was reassured that everyone in my family was fine. Thankfully, all we lost to Hurricane Katrina were material things.
As we mark another anniversary of the landfall of Hurricane Katrina on August 29, the memory of the infamous storm and its aftermath is still vivid for many current and former Gulf residents.
While New Orleans and many coastal communities have since been revitalized, some scars remain visible and serve as a reminder of the tremendous and destructive power of Mother Nature. They call on us to act now to prepare our communities for the next big storm.
River helps rebuild wetlands
In their most recent reports, the Intergovernmental Panel on Climate Change and the National Climate Assessment warned that as the climate continues to warm, the North Atlantic basin will likely experience more Category 4 and 5 hurricanes.
While the Gulf Coast won’t necessarily see more storms in the future, scientists believe they may be more intense. This, combined with the effects of sea level rise, means the region’s communities and infrastructure will be increasingly vulnerable to storm surge and high winds associated with tropical storms.
At Environmental Defense Fund, we’re working as part of the Mississippi River Delta Restoration Coalition, to rebuild healthy wetlands in coastal Louisiana, using the natural power of the Mississippi River to take advantage of sediment in the river to rebuild land.
In addition to levees and other structural storm protection measures, the state needs resilient coastal wetlands to be part of its hurricane risk reduction system. Coastal wetlands can serve as an important buffer and retention area for storm surge.
That way, when the next big storm shows up, Louisiana communities and cities will be better protected.
Economic stakes are huge
For the last 40 years, EDF has been working to address the root causes of land loss in Louisiana and find innovative solutions to restore the delta. One-quarter of the state's coastal land area has disappeared since 1930 and Louisiana continues to lose land at an alarming rate – one football field every hour, on average.
Coastal restoration will help save jobs and industry vital to our economy, and help us build resilience against catastrophic storm surges like the one brought by Katrina.
It also has direct implications for important national and international economic and ecological systems:
- 100 million birds live in or pass through the delta each year, with 400 different species relying on the delta at some point during their life or migratory cycles.
- Louisiana has the largest commercial fishery in the lower 48 states.
- Five of the 15 largest ports in the country are in Louisiana, and 60 percent of all grain exported from the United States is shipped through the ports of New Orleans and South Louisiana.
- Louisiana is home to the Louisiana Offshore Oil Port, the only deep water oil port in the United States capable of offloading deep draft tankers.
Coming up: Peak hurricane season
With only three named storms to date in 2014, this year’s hurricane season has so far been unusually quiet. But today, nobody in Louisiana is sitting back.
The peak hurricane season, which falls between mid-August and the end of October, has only just begun. This means the Atlantic and Gulf Coasts may see more action soon enough.
At the same time, data show that the intensity and duration of hurricanes continue to increase. Louisianians know we must act now to restore our coast and the protection it gives us before the next Katrina comes along.No Comments
By Erin Greeson (National Audubon Society) and Alisha Renfro (National Wildlife Federation)
While there is no question that large-scale action is urgently needed to add address Louisiana’s land loss crisis, some questions surround the scientific solutions necessary to address this challenge. As the state of Louisiana advances its Coastal Master Plan and the comprehensive set of restoration projects within it, experts have opened discussion to scientists and interested members of the public to provide information, share science and encourage dialogue.
This week in New Orleans, the Expert Panel on Diversion Planning and Implementation had their second meeting, which offered an opportunity to reconvene for updates and discussion on sediment diversions – one of the key tools in Louisiana’s coastal restoration toolbox. In addition to addressing environmental concerns, the panel addressed social and economic questions about river diversions and the communities they will impact.
At the start of the meeting, Mr. King Milling, Chair of the Governor’s Advisory Commission on Coastal Protection, Restoration and Conservation, delivered a powerful reminder of Louisiana’s disappearing coast:
“Demise of this delta would be an environmental impact of international proportions: disaster for economy, culture, communities – all the things we do and live for in the delta. If we don’t proceed urgently, we will lose the delta. Nothing will stop this damage if we don’t proceed in an orderly fashion with large-scale, comprehensive solutions. This is not a time for debate. Our role is to address the issue of remarkable deterioration, and the state’s diversion committee will be addressing issues and conflicts. Its position is to focus on the larger picture of how we can preserve as much as we can, and how can we create a system that will protect as much as we can.”
The first day of the meeting was open to the public, and the agenda reflected many of the areas of focus that require follow-up from the panel’s first meeting. Presentations from the Army Corps of Engineers, The Water Institute of the Gulf and Biedenharn Group focused on the Hydrodynamic Study, which is collecting data in the river and using models to represent conditions in the river as it is today, predicting what the river will be like in the future without diversion projects and how the construction and operation of diversion projects change the river compared to the future without the diversions. They also briefly discussed the Mississippi River Delta Management Study, expected to begin soon, which will focus on the basin-side effects of diversions and evaluate combinations of diversion projects that maximize the number of acres of wetlands built or sustained over time.
Presentations from David Lindquist from the state’s Coastal Protection and Restoration Authority (CPRA) summarized the current state of knowledge on fisheries and wildlife response to existing freshwater diversions. Craig Colten, Ph.D. from the Water Institute of the Gulf highlighted the importance of considering the influences of restoration projects on communities.
A presentation from Micaela Coner and Bob Beduhn narrowed the discussion down to the engineering and design considerations of a single project – the Mid-Barataria Diversion. Ms. Coner, CPRA, discussed the Mid-Barataria sediment diversion project within the context of the 109 Coastal Master Plan projects. Speaking to the plan’s theme of reconnecting the river with its estuaries, she described sediment diversions as the best opportunity to build, maintain and sustain land.
Dr. Robert Twilley, Louisiana State University, described how the river once built natural resource wealth: “Natural resource economies and the flooding of the river once coexisted. The wealth of fisheries, and the wealth of the river building wetlands, once coexisted. Today, there’s a conflict. Historically, the river built land during big flood events. Nature had this figured out. We’re forcing a conflict. There is a resolution to this.”
During the closing portion of the meeting, attendees had opportunities to provide comments to the Expert Panel. Mississippi River Delta Restoration Coalition leaders were among the conversation.
David Muth of the National Wildlife Federation urged the panel to consider the historical context of the river in addressing site-specific questions about diversions: “We have glimpses from historical record about how productive this system once was. But for the past 300 years, we have been choking off that system.”
John Lopez of the Lake Pontchartrain Basin Foundation described the coastal land loss crisis in powerful terms and underscored for a sense of urgency: “This house is on fire. Lives are at risk. We have a great scientific challenge, but we don’t have time to delay.”
More background on the Expert Panel:
During its first meeting in January, the Expert Panel was asked to focus on the topics of uncertainty – underlying natural variability and limitations in knowledge – they perceived surrounding the design and operation of major freshwater and sediment diversions. A report summarizing their findings and recommendations from that first meeting was released in February.
In this report the panel focused on identifying six areas that should be answered or considered as sediment diversions move further from idea into planning, engineering and design:
- Data collection is important for understanding the system as it is today and for evaluating performance of individual diversion projects.
- A controlled sediment diversion does not currently exist, but some information needed to understand the time scales and extent of land building that could be expected from a controlled sediment diversion can be gleaned from natural crevasses.
- The response of plant, fish and wildlife communities to the operation of sediment diversions should be incorporated into modeling of different scenarios, both capacity and operation, of a diversion.
- The potential social and economic influences of a diversion project need to be considered to minimize any potential negative impacts that can be foreseen.
- Planning and design of diversion projects need to be explored under present day and possible future conditions (e.g. sea level rise, changes in precipitation) to maximize project success in the very near and long-term future.
- Communications between planners and stakeholders to discuss the realities and limitations of any predictions is essential for project success.
By Alisha A. Renfro, Ph.D., National Wildlife Federation
As spring weather warms the Midwest, snow melts and drains from 31 states into the Mississippi River. In south Louisiana, the mighty Mississippi River is nearing its peak flow of nearly 900,000 cubic feet of water per second. Rolling down the river with the water is mud and sand, which are essential to building wetlands in the disappearing Mississippi River Delta.
Every hour in Louisiana, a football field of land becomes open water. This land loss crisis is caused in part by levees built for flood protection and navigation which severed the connection between the delta and the river, almost completely halting the land-building processes that once created this iconic landscape.
Sediment diversions are large-scale restoration projects that move sand and mud from the river through the levees into nearby wetlands during high river flows – such as this year’s spring high water flow – to restart the land-building process and help sustain existing wetlands. One important question to understand the full land-building potential of these projects is: Is the Mississippi River a long-term, sustainable source of mud and sand?
A recent Nature Geoscience paper by Jeffrey Nittrouer, Ph.D. of River University and Enrica Viparelli, Ph.D. of the University of South Carolina, “Sand as a stable and sustainable resource for nourishing the Mississippi River delta,” suggests that while the amount of mud carried by the Mississippi River has decreased since the 1970s, the sand it carries has remained steady and may do so for the next 600 years.
The Missouri River is an important source of sediment to the Mississippi, historically supplying about one-half of the total sediment moving down the Mississippi River. However, dams built in the 1950s along the Missouri have been hypothesized as the cause of the large reduction in the amount of total sediment (mud plus sand) that makes its way down to the Mississippi.
In this study, Nittrouer and Viparelli look at changes in the mud and sand carried by the river over a year since the 1970s and found that while the amount of mud that makes it to Tarbert Landing, Miss. (306 miles above the Bird’s Foot delta) has decreased over time, the amount of sand has been consistent. They point out that the likely source of sand is material that is being eroded out of the river channel.
Nittrouer and Enrica applied a model to simulate the response of a sudden reduction in sediment supply that likely occurred with dam construction along the Missouri River in the 1950s. The model indicates that erosion of sand in the river channel between Cairo, Ill. and Vicksburg, Miss. keeps the amount of sand available at Tarbert Landing, Miss. steady for the next 600 years.
Sand and mud are both needed to restore the Mississippi River Delta. Sand, which is 20 percent of the sediment carried by the river, is essential for building new platforms that can support marsh vegetation. Mud, which makes up the other 80 percent, is necessary for maintaining and increasing the resiliency of existing marsh to sea level rise and storm events.
This study suggests that there is a steady supply of sand to the lowermost part of the Mississippi River that can be put to work by constructing and using sediment diversions to mimic nature to build new land, help sustain existing wetlands and begin the restoration of the Mississippi River Delta. This is positive news for large-scale coastal restoration efforts.No Comments
By Estelle Robichaux, Environmental Defense Fund
The Gulf of Mexico Research Initiative (GoMRI) hosted its 2014 Gulf of Mexico Oil Spill and Ecosystem Science Conference January 26-29 in Mobile, Ala. GoMRI was created soon after the 2010 Deepwater Horizon oil disaster when BP committed $500 million over 10 years to fund a broad, independent research program with the purpose of studying the environmental and public health impacts of the oil spill in the Gulf of Mexico.
The conference drew several hundred attendees from academia, state and federal agencies and non-governmental organizations who gathered to hear presentations on cutting-edge research about the impacts of the Gulf oil disaster and continuing socio-ecological recovery. This conference, the second of its kind, facilitates interdisciplinary discussion by giving GoMRI-funded researchers from many different fields an opportunity to come together.
The four-day event entailed around 150 oral presentations in 10 different sessions, more than 400 poster presentations and nearly a dozen other associated meetings, events and plenary sessions. Some of the conference sessions were very technical, including transportation of oil spill residues (i.e., tar balls and tar mats) and dispersants, and impacts of the oil spill on fisheries, coastal marshes and nearshore water ecosystems. Other sessions were technological, focusing on ecosystem monitoring and data management, while others examined the human side, looking at public health and socio-economic issues.
Some of the research coming out of the Coastal Waters Consortium is particularly interesting because it goes beyond the physical and chemical impacts of the spill, focusing on broader ecological issues such as coastal processes and food webs. Dr. Sabrina Taylor is the principle investigator looking at the post-spill reproductive success, survival and dispersal of the Seaside sparrow, a bird that lives its entire life on salt marsh and is very sensitive to environmental changing, making it an excellent “indicator species.”
Dr. Christy Bergeron Burns presented preliminary results showing less species abundance and less reproductive productivity for the Seaside sparrow in oiled versus unoiled areas of Barataria Bay, La. While the trend in abundance was less pronounced in 2013 than it was in 2012, the trends in reproductive indicators (number of nests, failed nests and fledglings) remained consistent. With more data to collect in 2014, this study has not yet reached any final conclusions. But these preliminary results are prompting questions that are shaping the ongoing research to determine the factors that are causing these trends: Has exposure to Polycyclic Aromatic Hydrocarbons or PAHs – compounds found in crude oil – directly impacted the bird’s reproductive success and habitat selection? Is PAH exposure, or environmental stress in general, affecting hormone levels in this species? Or has the primary food source of the birds – insects – been impacted by the spill somehow, indirectly affecting reproductive success and habitat selection of the Seaside sparrow?
After scientifically assessing the correlation of ecological changes to the Deepwater Horizon oil spill, researchers will dig deeper to understand what has actually caused these changes. Continued collection and analysis of data will give the scientific community a clearer, evidence-based picture of how the oil spill affected specific components of the Gulf ecosystem. But the Gulf Coast region will not get the most benefit from this extensive research until scientists have started to develop a more comprehensive, ecosystem-wide understanding of how the oil spill has impacted the Gulf of Mexico.No Comments
This was originally posted by Environmental Defense Fund on EDF Voices.
By Estelle Robichaux, Restoration Project Analyst, Environmental Defense Fund
Soon after my flyover of the Mississippi River Delta, I joined Dr. John Lopez of the Lake Pontchartrain Basin Foundation (LPBF) on a boat ride down the Bohemia Spillway to Mardi Gras Pass. As we sped down the spillway canal, beautiful swamp lilies and purple morning glories popped out against a backdrop of lush, green plants. Once we reached our destination, we saw an incredible number of birds: Laughing Gulls, Snowy Egrets, Great Blue and Tricolored Herons – just to name a few. This, along with an increase in the number of river otters and beavers observed, is a good indicator that there are healthy fish populations in the area.
Thirty-five miles southeast of New Orleans, Mardi Gras Pass is the Mississippi River’s newest and naturally evolving “distributary,” a channel of water that flows away from the main branch of the river. This new distributary began forming during the spring flood of 2011, when the water level of the Mississippi River was so high that it flowed over the natural levee in this area. When the floodwaters receded, Dr. Lopez and his team of scientists noticed two breaches in the embankment. These breaches continued to widen and deepen and soon, right around Mardi Gras Day 2012, the breach was complete. The Mississippi River was once again connected to the surrounding wetlands, allowing freshwater and land-building sediment back into the area.
Louisiana has lost 25% of its coastal land area since 1930 and continues to lose land at an alarming rate – one football field every hour, on average. Man-made levees along the Mississippi River cut off many small distributaries, like Mardi Gras Pass, from the wetlands in the floodplain of the river and have contributed to this massive wetland loss. Our team here at EDF works with partner organizations, including the Lake Pontchartrain Basin Foundation, as part of the Mississippi River Delta Restoration Coalition, which has a vision of reconnecting the Mississippi River to its delta to help protect people, wildlife and jobs in coastal Louisiana.
To address the complex, yet urgent need for coastal restoration in Louisiana, the state legislature unanimously passed the 2012 Coastal Master Plan. This plan is a long-term, science-based restoration program that includes nearly 250 restoration projects such as barrier island restoration, marsh creation, establishment of oyster barrier reefs and sediment diversions that will help rebuild Louisiana’s disappearing coast.
Restoring our coast, restoring my hope
One of the principal guidelines for restoration under the Coastal Master Plan is to address the root causes of land loss by using the natural power of the Mississippi River to build land at a large scale. Sediment diversions, a central component of the plan, embody this principle because they are designed to mimic the natural stages of the river and carry sediment to the areas of coastal Louisiana that need it most. By operating diversions at times of high water flow (like during a flood), large amounts of sediment can be diverted. It will then settle out in the wetlands and shallow bays, eventually building land mass in vulnerable coastal areas.
In a way, Mardi Gras Pass is a naturally occurring ‘pilot project’ of a sediment diversion. Knowledge gained from studying this area can tell us about the land-building properties, as well as the short-term effects, of sediment diversions. To learn more about this, LPBF scientists are studying how the reintroduction of freshwater and sediment to the spillway area is changing the wetlands and affecting wildlife populations.
Swift currents and downed trees along the edge of the flooded forest can make navigating Mardi Gras Pass somewhat treacherous, but we, in a trusty 14’ skiff, maneuvered through the channel and onto the Mississippi River for a brief but thrilling cruise.
This is what it means for the river to be connected to its floodplain, I thought as we emerged out onto the open water, this is what this ecosystem is supposed to be like.
Although I grew up only a few miles from it, this was the third time in my life I had been out on the Mississippi River and the first time it was in a boat small enough that I could reach down and touch its muddy waters. As our tiny boat circled out in that mighty river, despite the heat and the midday sun, I had goose bumps.No Comments