National Estuarine Research Reserve Research Articles

Permeable Reactive Barriers Designed To Mitigate Eutrophication Alter Bacterial Community Composition and Aquifer Redox Conditions.

Permeable reactive barriers (PRBs) consist of a labile carbon source that is positioned to intercept nitrate-laden groundwater to prevent eutrophication. Decomposition of carbon in the PRB drives groundwater anoxic, fostering microbial denitrification. Such PRBs are an ideal habitat to examine microbial community structure under high-nitrate, carbon-replete conditions in coastal aquifers. We examined a PRB installed at the Waquoit Bay National Estuarine Research Reserve in Falmouth, MA. Groundwater within and below the PRB was depleted in oxygen compared to groundwater at sites upgradient and at adjacent reference sites. Nitrate concentrations declined from a high of 25 μM upgradient and adjacent to the barrier to <0.1 μM within the PRB. We analyzed the total and active bacterial communities filtered from groundwater flowing through the PRB using amplicons of 16S rRNA and of the 16S rRNA genes. Analysis of the 16S rRNA genes collected from the PRB showed that the total bacterial community had high relative abundances of bacteria thought to have alternative metabolisms, such as fermentation, including candidate phyla OD1, OP3, TM7, and GN02. In contrast, the active bacteria had lower abundances of many of these bacteria, suggesting that the bacterial taxa that differentiate the PRB groundwater community were not actively growing. Among the environmental variables analyzed, dissolved oxygen concentration explained the largest proportion of total community structure. There was, however, no significant correlation between measured environmental parameters and the active microbial community, suggesting that controls on the active portion may differ from the community as a whole.

Evaluating nonindigenous species management in a Bayesian networks derived relative risk framework for Padilla Bay, WA, USA.

Many coastal regions are encountering issues with the spread of nonindigenous species (NIS). In this study, we conducted a regional risk assessment using a Bayesian network relative risk model (BN-RRM) to analyze multiple vectors of NIS introductions to Padilla Bay, Washington, a National Estuarine Research Reserve. We had 3 objectives in this study. The 1st objective was to determine whether the BN-RRM could be used to calculate risk from NIS introductions for Padilla Bay. Our 2nd objective was to determine which regions and endpoints were at greatest risk from NIS introductions. Our 3rd objective was to incorporate a management option into the model and predict endpoint risk if it were to be implemented. Eradication can occur at different stages of NIS invasions, such as the elimination of these species before being introduced to the habitat or removal of the species after settlement. We incorporated the ballast water treatment management scenario into the model, observed the risk to the endpoints, and compared this risk with the initial risk estimates. The model results indicated that the southern portion of the bay was at greatest risk because of NIS. Changes in community composition, Dungeness crab, and eelgrass were the endpoints most at risk from NIS introductions. The currents node, which controls the exposure of NIS to the bay from the surrounding marine environment, was the parameter that had the greatest influence on risk. The ballast water management scenario displayed an approximate 1% reduction in risk in this Padilla Bay case study. The models we developed provide an adaptable template for decision makers interested in managing NIS in other coastal regions and large bodies of water.

Does bird removal affect grasshopper grazing on Juncus roemerianus (black needlerush) marshes?

Grazing on J. roemerianus (black needlerush), grasshopper abundance, and black needlerush plants was examined in the presence and exclusion of marsh birds. Birds were excluded using a PVC framed exclosure wrapped with bird netting that allowed free passage of marsh grasshoppers. These measurements were taken bi-monthly from April to August 2011 in a black needlerush marsh within the Grand Bay National Estuarine Research Reserve (Moss Point, MS, USA). Grazing metrics, grasshopper abundance, and plant health metrics showed no effect of bird exclusions across all sampling dates. In contrast to other marsh systems with strong trophic cascades (e.g., Spartina alterniflora on US east coast), these results suggest that the primary consumer (grasshoppers) is not affected by the presence of their dominant predator (birds) which leads to no change in the health of the primary producer (black needlerush). Information derived from this study furthers our understanding of the trophic relationships within black needlerush marshes in the northern Gulf of Mexico.

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Jobos Bay National Estuarine Research Reserve (JBNERR) is located on the southern coast of Puerto Rico. Here, the mussel Brachiodontes exustus (Mollusca: Mytilidae) is abundant on mangrove roots. DNA damage levels in B. exustus mantle cells (measured using the comet assay at pH ~ 13) and metal concentrations in the remaining soft tissues (analyzed by atomic absorption spectroscopy) were measured at four sites in JBNERR. The lowest DNA damage levels were detected at the site closest to the open ocean. However, the DNA damage levels of B. exustus mantle tissue was consistently higher at the site closest to a thermoelectric power plant. These elevated damage levels could have been caused by the presence of genotoxic conditions at this site.

Meteorological Modeling Using the WRF-ARW Model for Grand Bay Intensive Studies of Atmospheric Mercury

Measurements at the Grand Bay National Estuarine Research Reserve support a range of research activities aimed at improving the understanding of the atmospheric fate and transport of mercury. Routine monitoring was enhanced by two intensive measurement periods conducted at the site in summer 2010 and spring 2011. Detailed meteorological data are required to properly represent the weather conditions, to determine the transport and dispersion of plumes and to understand the wet and dry deposition of mercury. To describe the mesoscale features that might influence future plume calculations for mercury episodes during the Grand Bay Intensive campaigns, fine-resolution meteorological simulations using the Weather Research and Forecasting (WRF) model were conducted with various initialization and nudging configurations. The WRF simulations with nudging generated reasonable results in comparison with conventional observations in the region and measurements obtained at the Grand Bay site, including surface and sounding data. The grid nudging, together with observational nudging, had a positive effect on wind prediction. However, the nudging of mass fields (temperature and moisture) led to overestimates of precipitation, which may introduce significant inaccuracies if the data were to be used for subsequent atmospheric mercury modeling. The regional flow prediction was also influenced by the reanalysis data used to initialize the WRF simulations. Even with observational nudging, the summer case simulation results in the fine resolution domain inherited features of the reanalysis data, resulting in different regional wind patterns. By contrast, the spring intensive period showed less influence from the reanalysis data.

The role of light, soil and human factors on the probability of occurrence of an invasive and three native plant species in coastal transitions of coastal Mississippi, USA

Aims Understanding relationships between the distributions of species and their surrounding environment provides a basis for forecasting how species will respond to future environmental changes. In this study, we examined the effects of environmental factors and human developmental features associated with disturbances on probability of occurrence of juveniles of invasive Triadica sebifera and three native plant species, Baccharis halimifolia, Ilex vomitoria and Morella cerifera within a typical coastal transition in coastal Mississippi, USA. Methods We recorded presence of juveniles of focal species and measured environmental factors (soil salinity, canopy openness, soil texture and soil carbon to nitrogen ratio) along an 11.3 km transect located at Grand Bay National Estuarine Research Reserve. Further, we documented anthropogenic features and associated activities as a proxy for human disturbance.

An integrated assessment of habitat quality of national estuarine research reserves in the southeastern United States.

Multiple indicators of water quality, sediment quality, and biological condition were used to assess the status of ecological condition of National Estuarine Research Reserve System (NERRS) sites in North Carolina, South Carolina, and Georgia relative to a suite of corresponding scoring criteria. All measurements were made in subtidal aquatic habitats. Calculated scores were integrated into an overall index of habitat quality and used to make comparisons among the various NERR and nonNERR estuaries throughout the region. Sediment quality scores varied considerably among NERR sites, but in most cases were similar between individual NERR and non-NERR sites in corresponding states. Water quality and biological condition indicators scored consistently higher for NERRs versus non-NERR sites. Overall habitat quality scores also were consistently higher for NERRS sites, suggesting that these areas are on par with if not in slightly better condition ecologically than neighboring nonNERR estuaries. Portions of individual NERR sites rated as poor with respect to overall habitat quality were limited to relatively small areas (<13% of a reserve's total sampling area).

Nekton and Macro-Crustacean Habitat Use of Mississippi Micro-Tidal Salt Marsh Landscapes

Salt marshes have long been recognized as productive habitats that form an important trophic link between the aquatic and terrestrial biomes through the dynamic intertidal zone. This project focused on the distribution of nekton (free-swimming organisms) and common macro-crustaceans within the intertidal to assess the breadth of habitat use by these assemblages based on geo-spatial and hydrological variables. Sampling was conducted on the flooded marsh intertidal in August and September 2011 at three sites in the micro-tidal Grand Bay National Estuarine Research Reserve, MS, using bottomless lift nets and pit traps in a landscape design. The sampled assemblage data were compared with concurrent site hydrological analyses in order to determine how distribution on the salt marsh intertidal may be influenced by defined inundation components (e.g., inundation time and frequency of inundation) and by the distance to the nearest water source. A total of 3238 organisms were collected comprising 12 fish and 13 macro-crustacean species. A two-way nested analysis of similarities (ANOSIM) indicated that the density of the assemblage varied by site (p = 0.1 %) and across the salt marsh intertidal (marsh level (MLV); p = 1.4 %). Overall, assemblages were found to be strongly influenced by the inundation characteristics along the marsh elevation gradient as well as by the unique micro-topography of each site.

Distribution and sources of PCBs (Aroclor 1268) in the Sapelo Island National Estuarine Research Reserve

Aroclor 1268 is a highly chlorinated PCB mixture that was released into the aquatic environment near Brunswick, GA (BR), as a result of decades of local industrial activity. This extensive contamination has led to US EPA Superfund designation in estuarine areas in and around Purvis Creek, GA. Roughly 50km to the northeast is the Sapelo Island National Estuarine Research Reserve (SI) where previous studies have documented unexpectedly high Aroclor 1268-like PCB levels in blubber and plasma samples of resident bottlenose dolphins. This result led to a collaborative effort to assess the PCB patterns and concentrations in SI sediment and fish (as potential vectors for PCB transfer to SI resident dolphins). Thirty SI randomly assigned stations were sampled for sediment PCB levels. Additionally, fish were collected and analyzed from SI (n = 31) and BR (n = 33). Results were pooled with regional assessments of PCB concentrations from South Carolina and North Carolina in an effort to determine the association of Aroclor 1268 levels in SI samples. Results indicated that PCB levels in sediment and fish are much lower in the SI estuary compared to BR sediment and fish concentrations. However, PCB congener profiles for both sediments and fish were similar between the two locations and consistent with the Aroclor 1268 signature, indicating possible transport from the Brunswick area. A likely source of Aroclor 1268 in dolphins from SI is contaminated fish prey.

Hurricane wrack generates landscape‐level heterogeneity in coastal pine savanna

Wrack (vegetation debris) deposited by storm surges of major hurricanes along the northern Gulf of Mexico produces depressant effects that vary from partial to complete mortality of groundcover vegetation in coastal savannas. As wrack decomposes or is relocated by a subsequent hurricane, patches are opened to colonization. We postulated that patterns of wrack deposition and removal, coupled with differential responses by savanna plant species should produce alternate states of groundcover vegetation. We explored extreme effects of wrack deposited by Hurricane Katrina (2005) in savannas dominated by slash pinePinus elliottiiand cordgrassSpartina patensand located above mean high tide at the Grand Bay National Estuarine Research Reserve, Mississippi, USA. In 2008, we established plots in adjacent areas with and without wrack deposits. Almost no groundcover plant species occurred in wrack deposits compared to adjacent groundcover without wrack. We simulated redistribution of wrack during a new storm surge by removing wrack from replicated plots and depositing it in plots without wrack, recording plant species in treatment and control plots before, then one month and one year after manipulations. One year later, about half the species present before wrack addition (especially dominant graminoids) grew back through redistributed wrack, suggesting that some species were resistant to burial of limited amounts of wrack. Wrack removal resulted in germination and establishment of numerous herbaceous plant species not in undisturbed groundcover, doubling total aboveground numbers of species in the pine savanna and shifting groundcover communities to alternate states not present prior to Katrina. Removal of wrack opens space colonized by resilient species, including those transported in wrack and those surviving intervals between disturbances belowground. Wrack dynamics (deposition and removal) generated alternate states that resulted from resistance‐ and resilience‐driven changes in different patches of groundcover in coastal savannas.

Mercury Speciation at a Coastal Site in the Northern Gulf of Mexico: Results from the Grand Bay Intensive Studies in Summer 2010 and Spring 2011

During two intensive studies in summer 2010 and spring 2011, measurements of mercury species including gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM), trace chemical species including O3, SO2, CO, NO, NOY, and black carbon, and meteorological parameters were made at an Atmospheric Mercury Network (AMNet) site at the Grand Bay National Estuarine Research Reserve (NERR) in Moss Point, Mississippi. Surface measurements indicate that the mean mercury concentrations were 1.42 ± 0.12 ng∙m−3 for GEM, 5.4 ± 10.2 pg∙m−3 for GOM, and 3.1 ± 1.9 pg∙m−3 for PBM during the summer 2010 intensive and 1.53 ± 0.11 ng∙m−3 for GEM, 5.3 ± 10.2 pg∙m−3 for GOM, and 5.7 ± 6.2 pg∙m−3 for PBM during the spring 2011 intensive. Elevated daytime GOM levels (&gt;20 pg∙m−3) were observed on a few days in each study and were usually associated with either elevated O3 (&gt;50 ppbv), BrO, and solar radiation or elevated SO2 (&gt;a few ppbv) but lower O3 (~20–40 ppbv). This behavior suggests two potential sources of GOM: photochemical oxidation of GEM and direct emissions of GOM from nearby local sources. Lack of correlation between GOM and Beryllium-7 (7Be) suggests little influence on surface GOM from downward mixing of GOM from the upper troposphere. These data were analyzed using the HYSPLIT back trajectory model and principal component analysis in order to develop source-receptor relationships for mercury species in this coastal environment. Trajectory frequency analysis shows that high GOM events were generally associated with high frequencies of the trajectories passing through the areas with high mercury emissions, while low GOM levels were largely associated the trajectories passing through relatively clean areas. Principal component analysis also reveals two main factors: direct emission and photochemical processes that were clustered with high GOM and PBM. This study indicates that the receptor site, which is located in a coastal environment of the Gulf of Mexico, experienced impacts from mercury sources that are both local and regional in nature.

Influence of changes in developed land and precipitation on hydrology of a coastal Texas watershed

Freshwater inflows, among the most important factors in the overall health of estuarine environments, can be altered both by regional climatic influences as well as changes in land use and land cover. We conduct a scenario analysis to study the individual and combined impacts of changes in land use and land cover and in precipitation patterns in a coastal Texas watershed. The watershed is one of the major sources of freshwater for the estuarine area within the Mission-Aransas National Estuarine Research Reserve (NERR). Our scenario analysis suggests that climatic changes are more influential than land changes at the watershed level. However, localized impacts of land change may still be significant on habitats within the NERR site. Results from our watershed-level analysis poorly agree with the recommended freshwater flows established for the region, which deserve further scrutiny. Our findings suggest that geomorphic characteristics of the streams in the watershed need to be taken into consideration in hydrological modeling. Further research on the interactions between land change and hydrological dynamics should also aim for tighter temporal integration of the two sets of processes.

Sentinel Site Development of a Major Salt Marsh System in the Mid-Atlantic Region (USA)

The Tuckerton Peninsula, a large expanse (~2000 ha) of highly inundated Spartina alterniflora salt marsh habitat, forms one of the most extensive coastal wetland systems in New Jersey (USA). It is projected to be among the first salt marsh systems in New Jersey to be lost by rising sea level driven by climate change. The changes that occur in the demographic, ecologic, and ecogeomorphic characteristics of the salt marsh habitat at this location will be vital to understanding future habitat change in coastal wetlands in the Mid-Atlantic region. As a consequence, the Tuckerton Peninsula salt marsh system is designated as a sentinel site of the Jacques Cousteau National Estuarine Research Reserve (JCNERR) for the detection, monitoring, and assessment of climate change effects, most notably sea-level rise and inundation. Development of the Tuckerton Peninsula as a sentinel site requires a high accuracy local geodetic control network to connect existing water quality monitoring stations, vegetation transects and monitoring surface elevation tables, ground water wells, and digital elevation models on the same vertical datum. The integration of these monitoring infrastructure components is crucial to effective operation of the sentinel site. It will enable the collection of essential data to assess rates of marsh migration and upland transgression, as well as delineate key natural and anthropogenic drivers influencing habitat condition and change. The JCNERR sentinel site designation supports the National Oceanic and Atmospheric Administration’s long-term goal of assessing coastal vulnerability in the USA to climate change and generating data useful for forging climate adaptation and mitigation initiatives for coastal communities. Habitat and vertical control data collected at this sentinel site will be made available to decision makers across the nation and will enable them to determine how the loss of critical salt marsh habitat will affect coastal communities, their adaptation to future habitat loss, and their development of mitigation plans to address impacts and enhance resiliency.

Modeling of Inundation Characteristics of a Microtidal Saltmarsh, Grand Bay National Estuarine Research Reserve, Mississippi

Ennis, B.; Peterson, M.S., and Strange, T.P., 2014. Modeling of inundation characteristics of a microtidal saltmarsh, Grand Bay National Estuarine Research Reserve, Mississippi. Intertidal saltmarsh habitats are unique productive estuarine systems in that their relative productivity is strongly influenced by the morphology of the landscape and the degree of water inundation. Despite the recognized effect that flooding in saltmarsh intertidal zones has on the natural history of resident fauna and the conservation of the habitat itself, limited data are available with regard to hydrological conditions to conduct proper assessment of these habitats. In this paper we describe a geographic information system–based model that was used to quantify the inundation characteristics of intertidal habitats within the microtidal Crooked Bayou, Grand Bay National Estuarine Research Reserves (GNDNERR), Mississippi, system. Using water levels from a nearby National Oceanic and Atmospheric Administration tide station, inundation characteristics were generated by the model for multiple sample sites and for plots within each site along a common marsh elevation gradient. The derived characteristics generated by the model were used in a principal components analysis to create factor scores depicting flooding conditions. These factor scores were then used as the means of comparison of cumulative inundation characteristics between sites and the plots within sites. Overall, inundation characteristics were found to vary significantly between sampling sites (Kruskal-Wallis, χ2 = 26.13, p < 0.001) and among the plots (Friedman's, χ2 = 19.27, p < 0.001) across the elevation gradient. In general, although the inundation potential of the sampling plots within each site significantly decreased as the marsh elevation gradient increased, there were marked differences among and within sites because of the considerable microtopography patterns we identified that exemplify the microtidal, low-lying intertidal landscape of GNDNERR.

Impacts of Sea Level Rise on Marsh as Fish Habitat

Sea level rise and accompanying coastal squeeze will drive changes in marsh spatial configuration and connectivity affecting how fishes utilize the marsh. We investigate how sea level rise and coastal squeeze affect the spatial distribution, configuration, and connectivity within tidal marshes in a landscape context. Using spatial analyses, we compare two outputs from a process model: one with constant vertical accretion and the other with a more optimistic prediction that rates of vertical accretion will equal rates of sea level rise. We use landscape metrics on the model outputs to evaluate the landscape scale changes that occur in a selected marsh at the National Estuarine Research Reserve (NERR) site in Wells, Maine, USA. We found that moderate sea level rise would benefit marshes by expanding their area and maintaining habitat spatial complexity. However, rapid sea level coupled with stressors like coastal squeeze is likely to result in smaller and more dispersed marshes with simpler patch edges and less connected patches. Such features indicate lesser potential for food and refugia.

Effects of Northeaster Storms on Water Level and Turbidity in a Delaware Bay Subestuary

ABSTRACT Moskalski, S.M. and Sommerfield, C.K., 2013. Effects of northeaster storms on water level and turbidity in a Delaware Bay subestuary. Coastal storms have a major influence on the ecology and geomorphology of U.S. Atlantic estuaries and tidal marshes. The purpose of this study was to determine which types of storms are most effective in flooding the marsh platform with high-turbidity water, a condition conducive for sedimentation. Eleven years (2000–10) of continuous water level and turbidity data for the St. Jones River National Estuarine Research Reserve, a subestuary of Delaware Bay, were analyzed and compared to weather events registered in the National Climate Data Center Storm Events Database. Statistically significant water-level and turbidity reference values were established and used to identify storm-produced events in the data records. Results indicate that northeasters were responsible for most (41%) of all concurrent water-level and turbidity events; other types of weather conditions,...

Seasonal and Inter-annual Patterns in Primary Production, Respiration, and Net Ecosystem Metabolism in Three Estuaries in the Northeast Gulf of Mexico

Measurements of primary production and respiration provide fundamental information about the trophic status of aquatic ecosystems, yet such measurements are logistically difficult and expensive to sustain as part of long-term monitoring programs. However, ecosystem metabolism parameters can be inferred from high frequency water quality data collections using autonomous logging instruments. For this study, we analyzed such time series datasets from three Gulf of Mexico estuaries: Grand Bay, MS; Weeks Bay, AL; and Apalachicola Bay, FL. Data were acquired from NOAA's National Estuarine Research Reserve System Wide Monitoring Program and used to calculate gross primary production (GPP), ecosystem respiration (ER), and net ecosystem metabolism (NEM) using Odum's open water method. The three systems represent a diversity of estuaries typical of the Gulf of Mexico region, varying by as much as two orders of magnitude in key physical characteristics, such as estuarine area, watershed area, freshwater flow, and nutrient loading. In all three systems, GPP and ER displayed strong seasonality, peaking in summer and being lowest during winter. Peak rates of GPP and ER exceeded 200 mmol O2 m−2 day−1 in all three estuaries. To our knowledge, this is the first study examining long-term trends in rates of GPP, ER, and NEM in estuaries. Variability in metabolism tended to be small among sites within each estuary. Nitrogen loading was highest in Weeks Bay, almost two times greater than that in Apalachicola Bay and 35 times greater than to Grand Bay. These differences in nitrogen loading were reflected in average annual GPP rates, which ranged from 825 g C m−2 year−1 in Weeks Bay to 401 g C m−2 year−1 for Apalachicola Bay and 377 g C m−2 year−1 in Grand Bay. Despite the strong inter-annual patterns in freshwater flow and salinity, variability in metabolic rates was low, perhaps reflecting shifts in the relative importance of benthic and phytoplankton productivity, during different flow regimes. The advantage of the open water method is that it uses readily available and cost-effective sonde monitoring technology to estimate these fundamental estuarine processes, thus providing a potential means for examining long-term trends in net carbon balance. It also provides a historical benchmark for comparison to ongoing and future monitoring focused on documenting the effect of human activities on the coastal zone.

Impacts ofPhragmitesManagement on Marsh Wren Nesting Behavior

Abstract We monitored territory density, nest density, date of nest initiation, nest height, and associated vegetation characteristics of Marsh Wrens (Cistothorus palustris) in two marshes managed with herbicide in late summer 2009 to control Phragmites. Average territory density declined fourfold from 2.39 to 0.54 territories/ha (one-tailed t-test, P = 0.004), and average active nest density declined tenfold from 1.43 to 0.12 nests/ha (one-tailed t-test, P = 0.055) between 2009 and 2010. The mean date of nest initiation was twice as late in 2010 (21 Jul) as in 2009 (15 Jun), one-tailed t-test, P = 0.009. Mean nest height was similar (one-tailed t-test, P = 0.20) in 2009 (86.4 cm) and 2010 (79.6 cm), but the vegetation took longer to reach these heights in 2010, particularly at Old Woman Creek National Estuarine Research Reserve. These results suggest large scale aerial herbicide applications to manage Phragmites compromised productivity of Marsh Wrens in the coastal marshes studied. Caution shoul...

Atrazine fate and transport within the coastal zone in southeastern Puerto Rico

Agrichemical transport to coastal waters may have adverse ecological impact. This work examined atrazine fate and transport in a field adjacent to Puerto Rico’s Jobos Bay National Estuarine Research Reserve. The herbicide’s use was linked to residue detection in shallow groundwater and movement toward the estuary; however, data indicated that transport via this pathway was small. In contrast, surface runoff as tropical storm systems moved through the area appeared to have high potential for atrazine transport. In this case, transport to the estuary was limited by runoff event timing relative to atrazine application and very rapid atrazine dissipation (DT50=1–3days) in field soil. Soil incubation studies showed that accelerated degradation conditions had developed in the field due to repeated atrazine treatment. To improve weed management, atrazine replacement with other herbicide(s) is recommended. Use of products that have greater soil persistence may increase runoff risk.

Molecular Approach to Microbiological Examination of Water Quality in the Grand Bay National Estuarine Research Reserve (NERR) in Mississippi, USA

Grand Bay National Estuarine Research Reserve (NERR) is an important ecosystem in the Mississippi Gulf Coast. It serves as important nursery areas for juveniles of many species of fish. The bay is also used for fishing, crabbing, oyster togging, boating as well as recreation. Like in other aquatic environments, this bay may be contaminated by microorganisms including pathogenic bacteria. The objective of this study was to evaluate the microbiological quality of water in the Grand Bay NERR and determine the levels and potential source(s) of human fecal pollution. To achieve this goal, water samples were collected aseptically every month in Bayou Heron, Bayou Cumbest, Point Aux Chenes Bay and Bangs Lake. Enterococci were concentrated from water samples by membrane filtration according to the methodology outlined in USEPA Method 1600. After incubation, DNA was extracted from bacteria colonies on the membrane filters by using QIAamp DNA extraction kit. Water samples were also tested for the presence of traditional indicator bacteria including: heterotrophic plate count, total coliforms, fecal coliforms, and Enterococcus bacteria. The marker esp gene was detected in one site of Bayou Cumbest, an area where human populations reside. Data from this study indicates higher concentrations of indicator bacteria compared to the recommended acceptable levels. Presence of esp marker and high numbers of indicator bacteria suggest a public health concern for shellfish and water contact activities. Hence, control strategies should be developed and implemented to prevent further contamination of the Grand bay NERR waters.