Archive for Science
Straddling the border of Plaquemines and St. Bernard parishes in Southeastern Louisiana is the Caernarvon Freshwater Diversion built by the Army Corps of Engineers and operated since 1992 to balance water salinity by funneling river water into coastal marshes.
Lately, the diversion has had indirect effects that are raising eyebrows among scientists and those seeking to find solutions to address the crisis of Louisiana’s disappearing coast. The Caernarvon Freshwater Diversion is creating land at a rapid pace by delivering nutrient-rich river fresh water to bayous that have been starved of sediment and are eroding at an alarming rate.
In a new video, Coordinator of Lake Pontchartrain Basin Foundation’s Coastal Sustainability Program Dr. John Lopez outlines how approximately 1,000 acres of wetlands have been developed from the Caernarvon Diversion to create a new delta and within it a new bayou known as Bayou Bonjour. The new bayou is named in contrast to the book "Bayou Farewell," foretelling of the tragic loss of our wetlands and bayous. “Caernarvon was not designed or operated to build land,” Lopez notes, yet “Big Mar Pond has been filling up over the last twenty years due to sediment from Caernarvon.” How did this happen? Lopez explains how the diversion has provided an “ideal recipe for building a delta”: (river freshwater + sediments + nutrients = land growth).
Big Mar is located directly behind Braithwaite Park, a Plaquemines Parish community housed outside the federal levee system where devastation from Hurricanes Katrina, Rita, and Isaac occurred. Building land in Big Mar could provide a much-needed buffer for this community and an example for how to protect others like it. “As long as Caernarvon Diversion is flowing, this waterway and others like it will develop and this gives us hope in Louisiana that we can rebuild our coast,” says Lopez. In addition, recently planted cypress trees are thriving and will provide additional environmental and flood protection benefit as a new "line of defense."
Take a tour of Bayou Bonjour:
Want to learn more about the Caernarvon Diversion and other solutions for restoring the Mississippi River Delta? Visit mississippiriverdelta.org, like us on Facebook, and follow us on Twitter. You can also share the video with your network using the following tweet:
- Introducing Bayou Bonjour: Caernarvon Diversion has created an “ideal recipe for building a delta” #RestoreOurCoast http://youtu.be/5TExITZM2Wg
By Matthew Phillips, National Wildlife Federation
When trying to understand how ecosystems function, scientists often look at food webs–the complex relationships between animals, insects, plants, and bacteria that govern who eats whom.
Food webs in the Gulf of Mexico are as complex as they come. The different habitat types, from forests to wetlands to ocean, mean a diverse array of species. The Gulf food web would be nearly impossible to understand in its entirety, but we can simplify it into a chain to help us think about it. Plants form the base of this chain, as they convert sunlight into the energy that fuels the entire system. Plants are eaten by herbivores, who are then eaten by larger organisms. Scientists can learn a lot about how an ecosystem functions by studying the ends of the chain–the plants at the bottom and the animals that occupy the top. However, it’s the species in the middle that provide crucial linkages.
One recent study, “Disturbance and recovery of salt marsh arthropod communities following BP Deepwater Horizon oil spill” assessed how arthropods living in the Gulf wetlands responded to the BP oil spill. Arthropods are an enormous group of organisms, including insects, spiders, crabs, crustaceans, and just about anything else with a hard outer shell that lacks a vertebral column. The authors looked at the heart of the food chain: the huge number of arthropod species that provide links between fish, birds, and other animals. If the oil spill affected these populations, they reasoned, the effects would ripple through the rest of ecosystem, causing unpredictable damage.
They measured the density of arthropod populations in patches of Spartina alterniflora, a grass that dominates Gulf coast marshes, while oil was washing up on marsh shoreline in 2010 and again one year later. For comparison, they visited 12 marshes with oil and 10 with no oil. They ensured the vegetation and soil were similar in each location to negate any differences between habitat types.
Their results were both striking and hopeful. During 2010, they found half as many arthropods in the marshes that had oil as in those with no oil. Because birds, fish, and even plants depend on these organisms, losing half the population could potentially devastate the ecosystem. But by 2011 arthropods in the oiled marshes were back at the same densities as in the unoiled marshes. It seemed that arthropods were primarily susceptible to the direct effects of oil. Oil may remain in wetlands for decades after a spill, but it usually seeps into the soils under the marsh grass. The arthropods in this study lived in the grasses above the marsh surface. Once the oil disappeared into the soil, their populations returned to normal.
This study presents a more important conclusion than simply the resilience of arthropods to oil. Ecosystems are intricate webs of interactions between the living and non-living environment, and looking at one organism, relationship, or phenomenon may not reveal any significant truth about the ecosystem as a whole. Except for a thin sheen of oil, the marshes in this study appeared healthy. But, in fact, oil had wiped out half the arthropods. We should treat ecosystems as the fragile, profoundly complex systems they are. Protecting them should be the top priority. Any disturbance can have widespread and unpredictable consequences.
To learn more about our coalition and the plans to restore our marshes and wetlands, click here. More information about the ongoing effects of the BP oil spill can be found here: "Understanding effects of chemical dispersants on marine wildlife is critical to whale population" and "Five years later, scientists gather to assess ongoing impact of BP oil spill."No Comments
This was originally posted on the National Wildlife Federation's Wildlife Promise blog.
By Emily Guidry Schatzel, National Wildlife Federation
One day after BP released a report saying the Gulf is on the road to recovery, we took a trip to one of the most impacted areas from the BP oil spill—Barataria Bay, Louisiana. From a dead baby dolphin to devastation at a bird rookery to active clean-up crews removing tons of oil from barrier islands, we found a very different picture from what BP painted in its report.
We started the day off at Cat Island. Once a vibrant barrier island covered in brown pelicans, roseate spoonbills, terns and gulls, it was hit hard by the oil during the spill. Today, the island is unrecognizable. The thick mangrove forests are all dead and the island is essentially a small spit of mud with the skeletal remains of vegetation, hosting just a handful of birds. Coastal Louisiana is already losing a football field of land every hour, and studies show that the oil accelerated this erosion.
Next we went to East Grand Terre, a nearby barrier island. Roughly 20 workers were out there cleaning up oil. BP confirmed this latest clean-up was part of a process to remove a 25,000-pound tar mat found in late February 2015. Finding oil here is not a huge surprise–two years ago, a 40,000 pound tar mat was found in the same area.
Even worse, in that same area, we also saw a mother dolphin attempting to resuscitate her dead infant. She was surrounded by a group of dolphins–all of them visibly in distress. Such a tragic sight was difficult to witness.
On the same day, The Lens reported that two dead adult bottlenose dolphins washed up on nearby Queen Bess Island.
We don’t know why these particular dolphins died. But we do know that NOAA has determined bottlenose dolphins in this area of Barataria Bay are sick—very sick. They have symptoms of oil exposure—unusual lung masses, adrenal gland problems, even teeth that are falling out. Based on the study, NOAA concluded that “the health effects seen in the Barataria Bay dolphins are significant and likely will lead to reduced survival and ability to reproduce.”
We also know that dolphin deaths in Louisiana remain four times higher than average. And that high numbers of stillborn and premature dolphins have been found in the northern Gulf every spring since 2010.2 Comments
This was originally posted on the National Wildlife Federation's Wildlife Promise blog.
By Ryan Fikes, National Wildlife Federation
BP has just released a new report on the state of the Gulf, called Gulf of Mexico: Environmental Recovery and Restoration. The glossy report is filled with footnotes and citations, but leaves key pieces of science out.
Here are ten important things BP’s latest report strategically didn’t mention:
- Dolphins died before the spill – from freshwater
The report says: “An “unusual mortality event” (UME) involving an abnormally high number of dolphin deaths in the Gulf of Mexico began in February 2010, months before the Deepwater Horizon accident.”
What it leaves out: The deaths of a cluster of dolphins during the months before the Deepwater Horizon exploded were likely caused by extended exposure to fresh water and unusually cold weather. (Source: NOAA)
- Gulf dolphins are now very susceptible to an old disease
The report says: “NOAA has said that brucella, a bacterium that can infect animals, is “a common thread” in a number of the animals examined. Nearly one-third of the dolphins tested as of Nov. 25, 2014 were positive for brucella.”
What it leaves out: In 2011, Teri Rowles, the coordinator of NOAA’s National Marine Mammal Health and Stranding Response Program said, “Severe environmental stress, including from exposure to oil, could have reduced the animals’ ability to fight infection.”(Source: NOAA)
And in 2013, NOAA released a study showing that dolphins in heavily-oiled Barataria Bay had adrenal gland problems consistent with oil exposure that would in fact harm their ability to fight infections.(Source: Environmental Science & Technology)
- For the Kemp's ridley, anything less than an increase is a decrease
The report says: “For Kemp’s ridley sea turtles, nesting numbers the two years after the accident were above historical averages.”
What it leaves out: Up until 2009, Kemp’s ridley nests were increasing exponentially (15-19%) every year. In 2011 and 2012, the number of Kemp’s ridley nests—while essentially the same as the
numbers seen in 2009—were still below expectations. Even more troubling are the significant decreases in nests seen in 2010, 2013, and 2014. (Source: Gulf States Marine Fisheries Commission)
- Sperm whales in the Gulf have high levels of toxic metals
The report says: “While data analysis is ongoing, BP has not seen any evidence indicating that oil or dispersant compounds from the Deepwater Horizon accident have impacted the health of whales in the Gulf.”
What it leaves out: Researchers have found higher levels of DNA-damaging metals such as chromium and nickel in sperm whales in the Gulf of Mexico compared to sperm whales elsewhere in the world. (Source: Environmental Science & Technology)
And a recent study found that the two dispersants used in the Deepwater Horizon spill—Corexit 9500 and 9527—were both found to be damaging to sperm whale cells and DNA. (Source: Aquatic Toxicology)
- Oil exposure damages fish development – in many species
The report says: “A study by university and government researchers examined the overlap between spawning habitat and oiled waters and concluded that the spawning area for bluefin tuna extended much farther west than previously known and that “the proportion of spawning habitat impacted by oil was generally predicted to be small (<10%).”
What it leaves out: Estimates vary on how many larval bluefin tuna may have been exposed. One NOAA study estimated that the figure could be as high as 20 percent. (Source: NOAA)
And a recent comprehensive laboratory study found that a chemical in Deepwater Horizon oil can cause irregular heartbeats in bluefin and yellowfin tuna that can lead to heart attacks, or even death. The resulting heartbeat changes significantly altered the development of other organs. The researchers suggest that many other vertebrate species in the Gulf could have been similarly affected. (Source: Science)
- Right after the spill, red snapper and other fish had unusual lesions
The report says: “Researchers from the University of South Alabama and Dauphin Island Sea Lab in Alabama took samples of reef fish from the Alabama and western Florida Panhandle coasts from January 2010 to June 2011. They found no significant evidence of diseased fish in those populations.”
What it leaves out: In the aftermath of the spill, a number of fish caught in the Gulf between eastern Louisiana and western Florida had unusual lesions or rotting fins. Lesions were most common in bottom-dwelling species, including red snapper, and were particularly common north of the wellhead. (Source: Transactions of the American Fisheries Society)
- An unusual lack of young red snapper
The report says: “In an Auburn University study published in 2014, researchers found no evidence that the spill affected young red snapper populations on reefs off the Alabama coast.”
What it leaves out: Both 2010 and 2011 had the lowest numbers of juvenile red snapper seen in the eastern Gulf fishery since 1994. (Source: NOAA SEDAR)
- Seaside sparrows on oiled sites less likely to fledge
The report says: “Data from studies that BP conducted independently indicate that in 2011, the spill did not adversely impact bird productivity – how successful birds are at producing offspring. Brown pelicans, laughing gulls, great egrets, black skimmers, bald eagles and ospreys were studied.
What it leaves out: Preliminary data from 2012 and 2013 indicate that seaside sparrows from nests on unoiled sites were significantly more likely to fledge than those on oiled sites.. (Source: BioScience)
- Oil is still washing up on beaches
The report says: “Since some of the heavily oiled areas were last surveyed a year or two earlier, NRDA teams resurveyed the areas in 2014 and determined that a total of just one mile remained heavily oiled.”
What it leaves out: Recent studies of beach shoreline in Alabama suggest that tar balls are likely to continue washing up for years to come on Gulf Coast beaches, and could pose a risk to organisms living on or near those beaches. (Source: Science of the Total Environment)
- Oil remains in Louisiana's coastal marshes
The report says: “A 2012 University of Florida study that measured the rate of marsh erosion in a limited geographic area in Louisiana showed that erosion rates returned to normal 18 months after the spill and that its impact was generally limited to the edge of the marshes.”
What it leaves out: In May 2013, three years after the spill, more than 80 miles of marsh shoreline in Louisiana remained visibly oiled. The long-term effects of the oiling of Gulf marshes are still unclear and may take decades to unfold. (Source: International Oil Spill Conference)
By Matthew Phillips, National Wildlife Federation
During and after the 2010 BP oil spill, clean-up crews relied heavily on chemical dispersants to break up oil slicks in the Gulf of Mexico. In total, crews used more than 2 million gallons of dispersants, namely Corexit 9500 and 9527, applying them directly to the head of the leaking well and over the surface waters of the Gulf. Dispersants break down oil into small droplets that easily mix with water and, in theory, biodegrade quickly. The intention is to reduce the amount of oil in an area, dispersing it throughout the water column. While debate continues over the efficacy of dispersants in cleaning up spills, their use continues to rise, despite little data on their suspected toxicity. For this reason, scientists have begun looking into the effects of these powerful chemicals on marine wildlife.
In a recent study out of the University of Southern Maine, “Chemical dispersants used in the Gulf of Mexico oil crisis are cytotoxic and genotoxic to sperm whale skin cells,” researchers tested the effects of the chemical dispersants Corexit 9500 and Corexit 9527 to sperm whale skin cells. There is a small population, around 1600 sperm whales, residing in the Gulf. Since these whales inhabit part of the area inundated with oil after the BP spill, there is a high chance some of these whales came into contact with oil, and with the dispersants. With so few whales, the population is highly susceptible to disturbance: any chaotic or harmful event threatens its overall vitality. In addition, the most recent IUCN Red List of Threatened Species classified sperm whales as Vulnerable, meaning they are at risk of extinction. Therefore, understanding the effects of chemical dispersants on sperm whales is critical for ensuring the population’s health and stability.
To begin the process, researchers grew skin cells from samples obtained from Gulf whales before the spill. They applied varying concentrations of the two dispersants to the cultured cells, and measured the effects for one day. Since chemicals can be harmful in different ways, researchers studied the dispersants’ toxicity to the cells (called cytotoxicity) and to chromosomes (called genotoxicity). They found both dispersants to be poisonous to the cells, but only Corexit 9527 to be toxic to the cells’ genetic material.
Cytotoxicity and genotoxicity have different implications. A chemical that is cytotoxic –poisonous only at the cellular level—may cause fatal or non-fatal issues for individual organisms, such as skin lesions or respiratory complications. A chemical that is genotoxic, that disrupts the functions of genes, can leave an imprint on the next generation. It may cause problems in mating, reproduction, or calf development. A sperm whale exposed to Corexit 9527 may be unable to reproduce. If she can reproduce, she may have mal-formed or non-reproductive offspring.
Genotoxicity can have lingering detrimental effects on the population as a whole, endangering its future. While it would be valuable to know which dispersant is more toxic, researchers caution it is difficult to compare them because the effects are very different. Corexit 9500 was slightly more cytotoxic, but Corexit 9527 was significantly more genotoxic. Ultimately, the choice of which to use may depend on which outcome is more, or perhaps less, desirable.
There is no way to determine how many whales were exposed to dispersants, nor the degree of exposure. But a 2014 study citing widespread health problems among Gulf marine mammals, including complications in fetus development, gives cause for concern. The population’s size, the toxicity of chemical dispersants, and reports of toxin-related health problems make clear that Gulf sperm whales are at risk. Researchers will continue monitoring the health of the population, and only time will illuminate the full effects. Until we know more, we’re left wondering: if dispersants harm wildlife, how useful are they?No Comments
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