Hydrologic Restoration of the Lac des Allemands Swamp, Barataria, Louisiana

Most of the forested wetlands of coastal Louisiana are in decline, primarily due to impoundment and increased flood duration. The Lac des Allemands swamp of Barataria Basin was a prime example of prolonged inundation prior to hydrologic restoration completed in February of 2018; the swamp had been impounded for over 60 years. To characterize restoration benefits, eight paired 625 m2 permanent sites were established close to and halfway between eight 30 m × 122 m gaps cut into the spoil bank of Bayou Chevreuil. During 2018, canopy closure increased by 20%. In addition, aboveground production of wood and leaves increased over 2017 from 2018–2020. Furthermore, natural regeneration has occurred annually and many of the seedlings are now approximately 1 m tall. In conclusion, hydrologic restoration of impounded wetlands in coastal Louisiana is an extremely cost-effective landscape restoration method.

A Review of 50 Years of Study of Hydrology, Wetland Dynamics, Aquatic Metabolism, Water Quality and Trophic Status, and Nutrient Biogeochemistry in the Barataria Basin, Mississippi Delta—System Functioning, Human Impacts and Restoration Approaches

Here we review an extensive series of studies of Barataria Basin, an economically and ecologically important coastal basin of the Mississippi Delta. Human activity has greatly altered the hydrology of the basin by decreasing riverine inflows from leveeing of the river and its distributaries, increasing runoff with high nutrient concentrations from agricultural fields, and channelization of wetlands of the basin interior that has altered flow paths to often bypass wetlands. This has resulted in degraded water quality in the upper basin and wetland loss in the lower basin. Trophic state analysis found the upper basin to be eutrophic and the lower basin to be mesotrophic. Gross aquatic primary production (GAPP) was highest in the upper basin, lowest in the mid basin, and intermediate in the lower basin. Forested wetlands in the upper basin have degraded over the past several decades due to increased periods of flooding, while there has been massive loss of emergent wetlands in the lower basin due to increasing water levels and pervasive alteration of hydrology. Restoration will entail reconnection of waterways with surrounding wetlands in the upper basin, and implementation of river sediment diversions, marsh creation using dredged sediments and barrier island restoration. Findings from this review are discussed in terms of the functioning of deltas globally.

Assessing Chlorophyll a Spatiotemporal Patterns Combining In Situ Continuous Fluorometry Measurements and Landsat 8/OLI Data across the Barataria Basin (Louisiana, USA)

The acquisition of reliable and accurate data to assess environmental changes over large spatial scales is one of the main limitations to determine the impact of eutrophication, and the effectiveness of management strategies in coastal systems. Here, we used a continuous in situ Chl-a fluorometry sensor and L8/OLI satellite data to develop an algorithm and map Chl-a spatial distribution to assess the impact of freshwater diversions and associated high nutrient loading rates in the Barataria Basin (BB) complex, a coastal system in the northern Gulf of Mexico. We collected water quality samples at 24 sampling stations and high-frequency continuous fluorometry in situ [Chl-a] data along a ~87 km transect from 2019–2020. Field [Chl-a] values were highly correlated (r = 0.86; p < 0.0001) with continuous in situ [Chl-a] fluorometry values. These continuous in situ [Chl-a] values were significantly related to a surface reflectance ratio ([B1 + B4]/B3) estimated using L8/OLI data (exponential model; R2 = 0.46; RMSE = 4.8, p < 0.0001). The statistical model replicated [Chl-a] spatial patterns across the BB complex. This work shows the utility of high-frequency continuous Chl-a fluorometry sampling coupled with L8/OLI image analysis to increase the frequency and number of field data sets to assess water quality conditions at large spatial scales in highly dynamic deltaic regions.

Multivariate Analyses of Water Quality Dynamics Over Four Decades in the Barataria Basin, Mississippi Delta

Here we examine a combined dataset of water quality dynamics in the Barataria Basin, Louisiana based on transect studies from 1977 to 1978 (Seaton) and from 1994 to 2016. The Davis Pond river diversion into Lake Cataouatche began discharging Mississippi River water into the mid-basin in 2005, and so the later dataset was divided in Pre- and Post-diversion periods. The stations from these three datasets (Seaton, Pre- and Post-diversion) were combined into eleven station groupings for statistical analysis that included ANOVA and principal component analysis. In addition, Trophic State Index (TSI) scores were calculated for each grouping during the three time periods. Lake Cataouatche changed the most with the opening of the Davis Pond river diversion, becoming clearer and less eutrophic with addition of river water, which passed through a large wetland area where sediments were retained before entering the lake. The TSI results for the Seaton re-analysis were very similar to the original analysis and to that of the Pre- and Post-diversion datasets, indicating that the trophic status of the basin waters has remained relatively unchanged. The upper-basin has remained eutrophic with degraded water quality while the lower-basin has remained more mesotrophic without significant water quality deterioration. A main cause of water quality deterioration is agricultural runoff and pervasive hydrologic alteration that bypasses wetlands and causes most runoff to flow directly into water bodies.

The annual flood pulse mediates crayfish as a major diet constituent of carnivorous fishes in south Louisiana

Anthropogenic modifications to river-floodplain systems can decouple floodplains from mainstem inputs, alter flood pulse dynamics, and disrupt population dynamics and trophic web stability of aquatic biota. The Atchafalaya River Basin (ARB) receives an annual flood pulse from the Mississippi River that contributes to high crayfish abundance. Conversely, reduced crayfish abundance in the Barataria Basin (BB) is attributed to the system no longer receiving an annual flood pulse from the Mississippi River. Therefore, the purpose of this research was to determine if the absence of an annual flood pulse and reduced crayfish abundance influenced the diets of carnivorous fishes by examining stomach contents of fishes from both basins. Stomach contents were grouped as crayfish, fish, non-crayfish invertebrate, and herpetological. Although the percent occurrence of crayfish in fish stomachs differed between floodplain inundation and low-water periods in the ARB, crayfish were still the major diet constituent of ARB fishes during both periods. Non-crayfish invertebrate was the major diet constituent in BB fishes, with crayfish ranking as the second fewest diet constituent present. Our results demonstrate how flood pulse dynamics influence crayfish, and ultimately trophic webs, in large river-floodplain systems.

Mitigating for coastal erosion and C loss in the Mississippi Delta; do river water diversion do more harm than good?

&lt;p&gt;Sediment, nutrient deprivation and saltwater intrusion, among other factors, are driving widespread organic soil collapse and marsh loss in the Mississippi River Delta. Freshwater wetland diversions were designed to reintroduce Mississippi River water and sediment into the adjacent basins to manage salinity and mitigate land loss. However, there is concern that loading of excess nutrients from the Mississippi River into Barataria Basin wetlands can potentially lead to increased soil OM decomposition, less soil strength or increasing buoyancy and decreased belowground biomass. A baseline study was effected of a 3,145 km&lt;sup&gt;2&lt;/sup&gt; area of wetlands and estuaries within Barataria Basin in 2007, in which the spatial variation in plant and soils were described at 140 stations before full scale diversion operations began in 2009. A subsequent spatial survey was conducted in 2018 after 11 years of diversion influence. By resampling the top 20 cm, separated into 0-10 cm and 10-20 cm layers, in 2018 provides an assessment of the status of those soils produced since 2007 and provides context for changing soil conditions. For the 2018 sampling, the soil &lt;/p&gt;

Restoring barrier habitat in Louisiana to compensate for natural resource injuries: Shell Island and Chenier Ronquille Barrier Restoration Projects

Coastal Louisiana received significant funds tied to BP penalties as a result of the Deepwater Horizon incident. As it is widely considered that the State of Louisiana sustained most of the damage due to this incident, there has been a firm push to waste no time in implementing habitat restoration projects. Sustaining the land on the coast of Louisiana is vital to our nation’s economy, as several of the nation’s largest ports are located on the Gulf coast in Louisiana. In addition, the ecosystems making up the Louisiana coast are important to sustain some of the largest and most valuable fisheries in the nation. Funded by BP Phase 3 Early Restoration, the goals of the Natural Resource Damage Assessment (NRDA) Outer Coast Restoration Project are to restore beach, dune, and marsh habitats to help compensate spill-related injuries to habitats and species, specifically brown pelicans, terns, skimmers, and gulls. Four island components in Louisiana were funded under this project; Shell Island Barrier Restoration, Chenier Ronquille Barrier Island Restoration, Caillou Lake Headlands Barrier Island Restoration, and North Breton Island Restoration (https://www. gulfspillrestoration.noaa.gov/louisiana-outer-coast-restoration, NOAA 2018). Shell Island and Chenier Ronquille are critical pieces of barrier shoreline within the Barataria Basin in Plaquemines Parish, Louisiana. These large-scale restoration projects were completed in the years following the Deepwater Horizon incident, creating new habitat and reinforcing Louisiana’s Gulf of Mexico shoreline. The Louisiana Coastal Protection and Restoration Authority (CPRA) finished construction of the Shell Island NRDA Restoration Project in 2017, which restored two barrier islands in Plaquemines Parish utilizing sand hydraulically dredged from the Mississippi River and pumped via pipeline over 20 miles over levees and through towns, marinas, and marshes to the coastline. The National Marine Fisheries Service (NMFS) also completed the Plaquemines Parish barrier island restoration at Chenier Ronquille in 2017 utilizing nearshore Gulf of Mexico sediment, restoring wetland, coastal, and nearshore habitat in the Barataria Basin. A design and construction overview is provided herein.