Salinity and Marine Mammal Dynamics in Barataria Basin: Historic Patterns and Modeled Diversion Scenarios

Abstract

Understanding spatiotemporal patterns of salinity in Barataria Basin in coastal Louisiana is important to better understand and manage operations of existing and proposed freshwater and sediment diversions from the Mississippi River into the estuary. In this study, a comprehensive salinity dataset was compiled which covered the entire basin and included data from 1990 through 2015. The data were aggregated into daily mean salinity timeseries across Barataria Basin at a variety of spatial scales and used to analyze historic patterns. Simulations were conducted with two hydrodynamic models, the Integrated Compartment Model (ICM) and Delft3D. The Delft3D model output was overlaid with observed geo-tagged locations of bottlenose dolphins that were sampled from the southwest quadrant of the basin. The ICM simulations were used to assess the impact of existing freshwater and proposed sediment diversion projects which reintroduce riverine water into the estuary. The salinity in the uppermost portions of the basin is sensitive primarily to the existing freshwater diversion, whereas additional flows from a proposed sediment diversion result in additional freshening. The lowermost region of the basin is most sensitive to the proposed sediment diversion; however, the magnitude varies by diverted flow volumes and assumed sea levels in the Gulf of Mexico.

Quantifying the Relative Importance of Riverine and Open‐Ocean Nitrogen Sources for Hypoxia Formation in the Northern Gulf of Mexico

“…However, a quantitative analysis of the relative importance of nutrient inputs from the Mississippi and Atchafalaya Rivers versus those from offshore has not yet been done. Such a quantification has become more relevant in light of recent discussions to divert river discharge toward coastal wetlands in order to reduce nutrient loads into the NGoM (e.g., Allison & Meselhe, ; Peyronnin et al, ; White et al, ). An increased discharge diversion toward the Atchafalaya River would likely change spatial patterns of stratification and affect hypoxia formation.…”

The geography of high‐priority conservation areas for marine mammals

“…For marine species, salinity represents an important variable in determining habitat suitability, which justifies it as an important variable associated with marine mammal species distributions. For example, a recent study performed on the salinity levels in an estuary located in the Gulf of Mexico showed that salinity gradients can influence the dynamics of bottlenose dolphins’ use of habitat, with the majority of dolphins preferring areas with high salinity (White et al, 2018). Salinity was the most important variable for complementarity groups UNK, TR and FA (Table 2).…”

Mitigating the Effects of Sea-Level Rise on Estuaries of the Mississippi Delta Plain Using River Diversions

“…This addition of the upwinding technique greatly increased the stability of salinity predictions. Further discussion and analysis of the ICM methodology, calibration, validation, model performance and analysis are provided in the Supplementary Materials as well as several peer reviewed articles [24][25][26][30][31][32][33][34] and technical reports [35][36][37][38][39][40][41].…”

“…Before the ICM was used to assess future hydrologic and landscape conditions throughout coastal Louisiana, the ICM-Hydro subroutine was run from 2006 to 2013 using observed salinity and water level data collected across coastal Louisiana. The descriptions of the data used for this run and discussions on general model performance and limitations can be found in previously published literature [28,[30][31][32]. This run is used to illustrate the current pattern of salinity fluctuations within the estuaries, against which simulations that include sea-level rise can be compared.…”