PC studies the changing channel dimensions caused by the water flowing through the pass from the Mississippi River. The introduction of the Mississippi River has brought in sediment to build new wetlands which has now been colonized with new growth of grasses and trees.   

So far, we have reached a few major conclusions about the pass although we continue to study it. Freshwater discharge has increased over time which allows more water flow. Growth in sediment deposits have increased and pioneer grasses and trees have taken root. Lastly, we know that many species of saltwater and freshwater fish are using the pass as well as mammals, birds, reptiles and crustaceans. 

PC has been investigating the spillway since 2007. Primarily we have studied periodic flooding, land loss and land gain, land elevation changes, and vegetation surveys. We also conducted extensive research during the 2011 Mississippi River flood.  

During the 2011 Mississippi River flood survey we saw that overtopping waters were captured quickly by small natural channels and gullies shortly after the water overtopped the natural levee. Little overland flow was observed, relegated to the forest found along the natural levee and not reaching the adjacent marshes.   

Our land loss analysis from 1932 to 2010 showed that there have been low land loss rates in the spillway since 1975. The Bohemia Spillway does not seem to suffer the same interior land loss as other parts of the coast. This stability may be the result of periodic pulses of water and sediment received from the Mississippi River during flood events but could also be due to underlying geology, or a combination of the two.   

Canals in the Bohemia Spillway are being reclaimed by infilling. This is a rare occurrence in southeast Louisiana where canals usually expand and contribute to interior marsh loss.  Through our observations and study, we have concluded that the pulsed flow from the Mississippi River in flood years since 1926 has contributed to the sustainability and resiliency of marshes in the Bohemia Spillway. 

The creation of the BSJ Urban Marsh has been a success; the marsh is resilient and functioning as intended. We met the goal of re-establishing fringing marsh habitat along the south shore of Lake Pontchartrain, even if at a small scale. Located in a highly urbanized environment, this marsh is a place people can enjoy and learn about wetlands. People are fishing and birding near the marsh, plants are colonizing the marsh and animals find precious refuge, habitat and food there. The BSJ Urban Marsh is one in a small chain of created, restored or remnant marshes fringing the south shore of Lake Pontchartrain that includes the Lincoln Beach marshes, Bucktown Mitigation Marsh, Lake Villa Pond, the Kenner Boat Launch marsh and LaBranche Wetlands. Conserving, restoring and creating these types of habitats establishes lost habitat and contributes to storm protection. BSJ Urban Marsh can be a model for how to create wetlands in high energy environments.      

In 2015, we noted a large swath of the land bridge where natural swamp regeneration seems to be underway. To determine if natural regeneration is occurring, PC set up a study that investigated the extent and density of natural swamp regeneration in the Maurepas land bridge.  

Over 600 trees comprised the sample for the regeneration study. The species composition, in general, consisted of many small individuals of red maple and green ash, medium sized individuals of black willow and black gum and larger individuals of water tupelo and bald cypress. However, bald cypress was found across a range of sizes with both small and large individuals present. In general, there was a trend of more individuals and more species found at lower soil salinity. 

Although this data set is limited, it does suggest that the swamp forest on the Maurepas Land Bridge is in the beginning stages of natural regeneration. The future of natural regeneration in the region is uncertain but there are a few factors that increase the chances of success. The closure of the MRGO (Mississippi River-Gulf Outlet) has decreased both the surface and soil salinity in the region, and salinity fluctuations have decreased. Over time, the continuation of this study will reveal the dynamics of natural swamp regeneration, including shifts in species composition, mortality, and the next generation of saplings that would become the future tree canopy. 

PC studied the Central Wetlands by collecting water depth, surface salinity, soil salinity and vegetation data. PC studied the Central Wetlands in order to understand the health of the region and what kinds of restoration are needed, feasible and realistic.  

Our findings determined that the Central Wetlands cannot be thought of as one large area under the same influences, and therefore restoration solutions do not apply universally across the entire area. Varying salinities, water depth and vegetation indicate precise and separate areas with different restoration needs. 

Learn more about our latest work in the Central Wetlands with multiple community partners as CWRC.

The Caernarvon Diversion has effectively converted what was once brackish, open water in Big Mar to intermediate and freshwater marsh, resulting in an increase in biodiversity and ecosystem services throughout the project area.  Since 2005, over 1,148 acres of land have been built because of the diversion. Due to the careful research and selection of planting sites, this project has had an 85-90% success rate of the trees planted.   

In addition, the intermediate / freshwater marsh provides critical nursery habitat for a variety of coastal species including shrimp, crabs, alligators and fish. The resulting estuarine biodiversity in these freshwater nurseries creates and supports biodiversity further up the food chain, attracting a variety of reptiles and waterfowl which have been observed by land managers and recreational users in the area.   

Swamp forest, such as the one reforested and regenerated at Big Mar, is effective in reducing storm surge and buffering wind and wave action. The location of this project is doubly useful as it is adjacent to the levee system. 

While the size of the hypoxic area in these sounds vary on a yearly basis, it always appears north of the Chandeleur Islands and into the Cat Island Channel. Many factors seem to contribute to this dynamic process, including water quality, winds, tides, currents and rainfall. Each year, the development, expansion and disappearance of the hypoxic area tends to occur in areas cut off from prevailing currents in the Gulf of Mexico. The cause of the formation of hypoxia may be a naturally induced phenomenon simply due to the lack of wind and wave energy during the summer. It does not appear that the development of bottom hypoxia east of the Mississippi River is driven by the input of excess nutrients, as it is for the Dead Zone. However, the exact cause of this hypoxia has not been found and study continues.