The marine and estuarine ecosystems and living resources of Mississippi are of considerable importance to the area’s ecology and to the state’s economy. Dissolved oxygen is an important water quality parameter in determining oyster habitat suitability. A coupled hydrodynamic-water quality model was developed to study the oyster habitat suitability of the Western Mississippi Sound (WMSS) in the Northern Gulf of Mexico. The Visual Environmental Fluid Dynamic Code (VEFDC) was used to create a non-uniform grid-based model in four layers of the estuary’s depth. The input data for the model were provided from measurement gauge stations available within and near the computational grid, and the Lower Pearl River Model developed by TetraTech. The coupled hydrodynamic-water quality model was calibrated and validated against measured observed data for 2009 to 2017. The model was calibrated to dissolved oxygen (DO), chlorophyll a, NH3, and PO4. The Root Mean Square Error (RMSE), and Coefficient of Determination (R2) were applied as absolute and relative statistical measures of model performance. Measured dissolved oxygen in the western MS Sound shows stratification with higher levels of oxygen at the surface and lower levels at the bottom. Atmospheric reaeration is a source for dissolved oxygen in the top layers. Sediment oxygen demand is a sink for dissolved oxygen in the bottom layers. This study investigates the role of sediment oxygen demand and wind-based reaeration on modeled dissolved oxygen.

The Harmful Algal BloomS Observation System (HABSOS) is a web based data collection and distribution system for harmful algal bloom (HAB) information in the Gulf of Mexico, operated by NOAA’s National Centers for Environmental Information (NCEI). The goal of HABSOS is to provide environmental managers, scientists, and the public a resource for HAB data and information, including the distribution, extent and timing of the blooms. Karenia brevis is currently the only HAB species contained in HABSOS, however the potential for inclusion of other species exists. HABSOS operates as a cooperative enterprise with Gulf of Mexico state agency partners that monitor Karenia brevis blooms and submit their near real-time data to the HABSOS database. HABSOS uses an ESRI mapping application to display the HAB data housed in its database. The map viewer application displays by default the last 28 days of K. brevis data from the current date, however the display period can be set to any time span within the HABSOS database. There are additional data sources incorporated into the map viewer including satellite-derived, oceanographic, and meteorological layers, such as chlorophyll, surface currents forecast, or surface winds. Furthermore, the K. brevis cell count data and associated environmental data are archived and publicly available from the NCEI archive, https://data.nodc.noaa.gov/cgi-bin/iso?id=gov.noaa.nodc:0120767. HABSOS is a unique resource utilized by a wide variety of user groups including academia, government agencies, private enterprise, non-profit organizations, and individuals.

Groundwater quality and quantity in Alabama’s coastal system are affected by natural and anthropogenic stressors, including most notably, climatic variations, tropical storms and hurricanes, sea-water intrusion, land-use changes, agricultural activities, and water usage due to increasing public-supply, industrial and irrigation demands. Monitoring activities established by the Geological Survey of Alabama Groundwater Assessment Program (GSA-GAP) are designed to evaluate these stressors on the Miocene aquifer, a three-component system comprised of shallow, middle, and deep zones, which supplies most of the groundwater to the region. Domestic wells are primarily sourced from the shallow zone, and public-supply, industrial, and agricultural wells derive groundwater from the middle and deep zones. Changes in hydraulic head, as reflected by water level and primarily due to usage, in all zones, are evaluated through two GSA-GAP monitoring networks, a periodic network and a real-time network. Water levels in periodic network wells are measured bi-yearly. Water level and specific conductance in real-time network wells are continuously monitored. Several of these wells are used to inform the Monitoring and Impact Group of the Alabama Drought Assessment and Planning Team. Specific conductance changes are evaluated to provide insight on potential contamination effects from tropical storm surge and hurricanes and are supplemented with data derived from groundwater analyses collected from piezometers installed along the Gulf Coast beach front. A new program recently initiated by the GSA-GAP uses major parameter analytical results from groundwater collected from public-supply wells in conjunction with historical results to evaluate long-term quality changes due to pumping. A concerted effort is being made to expand these networks to improve these assessments and to be proactive in the evaluation of Alabama’s coastal groundwater system.

Submarine groundwater discharge (SGD) is often an important, yet understudied, process in coastal estuarine systems. In the western Mississippi Sound, samples were taken of surface waters for chemical species typically enriched in SGD (i.e., Ra quartet, Ba, methane, 222Rn, nutrients). Mass balance approaches were used on the radon and radium isotopes to determine an estimated water flux from SGD to the Sound. The radon and radium estimated SGD fluxes were 7.0×106 m3/d (0.04 m/d) and 9.1×106 m3/d (0.05 m/d), respectively. The local river input from the Pearl, Wolf, and Jourdan Rivers combined to this area has an average of 3.2×107 m3/d flux to the western Sound. Based on this average, the SGD flux was between 22% and 28% of river input. While SGD is only a fraction of riverine water flux, estimates of SGD nutrient fluxes (DIN, DIP, DSi) indicate that SGD is an equivalent or greater source of nutrients to the Sound as compared with local rivers. This could mean that SGD is the main source of nutrients to the Sound when river fluxes are lower than normal. A time series along the coastline of the Sound where there were elevated radon signatures during several surveys was also conducted. Monthly, five sites were sampled over the course of 17 months (June 2018 - November 2019), including during the opening of the Bonnet Carré Spillway (BCS), a diversion that keeps flood waters of the Mississippi River from reaching New Orleans. The average seepage measured during the time series was 0.08 m/d, but when the local rivers experienced extremely low discharge, groundwater influence increased, and during August 2018, the seepage was up to 0.19 m/d. However, with increasing river discharge in the winter months, along with BCS influence, the SGD input became negligible in the winter/spring of 2018/19.

Ecosystem restoration has been globally recognized as a key component of conservation programs and is considered essential to the long-term sustainability of many ecosystems. However, little information exists on the impacts these ecologically-based land management activities have on environmental quality. Exposing bare mineral soil following prescribed fire and herbicide treatment can result in surface erosion and increased sediment transport to stream channels. Beyond sediment transport, it is known that fires result in large fluxes of nitrate that leach into surface and groundwater. Any activities that increase nitrate delivery to surface water could further exacerbate eutrophication in local streams and hypoxia in the Gulf of Mexico and require serious consideration. To understand the impacts of coastal forest ecosystem restoration activities, we established a field experiment at the Infinity Science Center in Pearlington, Mississippi in summer 2020 to monitor long-term changes in water quality and soil health. Water quality measurements of surface and shallow groundwater include electrical conductivity, pH, turbidity, dissolved oxygen, nitrate, ammonium, total nitrogen, phosphate, total phosphorus, and dissolved organic carbon. Soil quality measurements include total carbon, total nitrogen, inorganic nitrogen transformations, and respiration. While laboratory analyses are still pending, results from this study are expected to aid in our understanding of the association between different land management activities commonly employed in restoration efforts on water quality and soil health.

In spring and summer of 2019, the two openings of the Bonnet Carré Spillway represented an unprecedented change from natural modes of variability to an engineered diversion in a coastal system. The abundance of river discharge diverted by this event has an unknown potential for impacts on water quality and coastal dynamics in this region. Using a combination of data from shelf hydrographic surveys and a mooring site during the event, the dissolved oxygen dynamics on the shelf are investigated. Extensive of areas of hypoxia on the shelf were observed throughout the summer study period with high variability in both space and time. Of particular interest was a regularly occurring mid-water column dissolved oxygen minimum, which in one incidence was hypoxic and had lower dissolved oxygen levels than bottom waters. Furthermore, time series data of bottom dissolved oxygen from June through September were highly correlated with changes in bottom temperature, revealing a significant connection to upwelling/downwelling events and the presence or absence of hypoxia on the inner to mid-shelf. The results of this study are expected facilitate the development of more effective mitigation and adaptation strategies in response to current and predicted changes in coastal oceans.