Louisiana Gulf Coast Research Articles

Improving Crew Overboard Recovery for Commercial Fishing in the Gulf of Mexico

ABSTRACT Occupational fatality rates in the commercial fishing industry in the United States remain more than 20 times higher than the national average. The burden of commercial fishing fatalities due to unintentional falls overboard is highest in the Gulf of Mexico (GOM) shrimp fishery. The objective of this quasi-experimental, pre-/post-test project design was disseminating recovery slings to GOM captains/deckhands, training in their use, and assessing the attitudes, beliefs, and intentions of fishermen in their adoption. Due to the COVID−19 pandemic, a land-based simulation was used to train commercial fishermen at three port locations in use of crew overboard (COB) recovery slings. A survey was developed to assess the attitudes, beliefs, and intentions of commercial fishermen in COB recovery. Purposive sampling was employed to recruit 30–50 fishermen at each location. Following pre-/post-training surveys, fishermen received one recovery sling per vessel along with a task list of instructions for use of the sling. A third survey and task list questions were performed at 12–18 months. There were 119 recovery slings and training in their use provided to 123 commercial shrimp fishing vessel owners/captains and deckhands along the Texas and Louisiana Gulf Coast. Repeated measures analysis of variance of the three surveys showed that positive change in normative beliefs was significant for the importance of quickly and safely maneuvering the vessel to the crew member. This change was most significant over the period from the initial training and receipt of the recovery sling by the vessel captain/deckhand, to the time of follow-up 12–18 months later (p = .03). Regarding control beliefs, training was associated with immediate statistically significant improved confidence that, with assistance, the fisherman would be able to use the sling and other equipment to hoist the COB (p = .02). However, this confidence waned significantly over time (p = .03). Attitudes and beliefs of commercial fishermen in the GOM can be favorably influenced toward a COB recovery device, as well as their confidence, and intention to use such devices. However, results show that attitudes and beliefs may wane over time, emphasizing the importance of repeated training and survival drills in this industry.

Sources and chemical stability of soil organic carbon in natural and created coastal marshes of Louisiana

Coastal marshes are globally important for sequestering carbon, yet sea-level rise and anthropogenic stressors can reduce their capacity as carbon sinks. Marsh restoration can offset a portion of carbon loss through the degradation of natural marshes, but potential differences in the sources and stability of soil organic carbon (SOC) between created and natural marshes may affect their function as a long-term carbon sink. Here, we examine the sources and chemical stability of SOC in natural and created marshes across the Gulf coast of Louisiana, USA. Marshes were examined along an estuarine salinity gradient in a former interdistributary basin of the Mississippi River Delta and in six created marshes across a 32-year chronosequence and a natural reference marsh (n = 6) in the Chenier Plain. Carbon source was assessed using δ13C analysis and chemical stability was determined through an acid hydrolysis digestion that removed labile carbon (LC). Soil δ13C values suggested that the local vegetation dominated SOC in all natural marshes although brackish marshes had a mix of sources and degradation of SOC. Recalcitrant carbon (RC) was 72.2 ± 0.5 % of SOC across fresh, brackish and saline marshes. The depth-averaged RC accumulation rate was almost three times greater than LC accumulation rate, yet both contributed significantly to accretion and long-term SOC accumulation (124–132 g m−2 y−1 in natural marshes). RC and SOC accumulation rate increased with mineral sediment accumulation rate. For the created marshes, SOC became increasingly recalcitrant due to an increase in in-situ plant inputs, but accumulation rates were lower than the natural marshes. Overall, this study illustrates that natural marshes have a large stock of RC from the vegetation while dredge sediment created marshes have no plant-derived carbon initially, which accumulates slowly thereafter. Restoration practices may be improved by preserving and augmenting these deteriorating but carbon-rich natural marshes.

Environmental Health and Justice Impacts of Steam Cracker Facilities

Background/Aim: Steam crackers (SCs) convert gas feedstocks into ethylene and propylene (the building blocks of plastics) at high temperatures and release toxic/carcinogenic chemicals and greenhouse gases (GHGs). The recent shale boom in the United States (US) has incentivized the expansion of SCs, but analyses of their potential environmental health and justice impacts are limited. We described SC operations, constructed a US SC emissions inventory, and evaluated socioeconomic characteristics of populations residing in proximity to SCs. Methods: We searched peer-reviewed and gray literature to describe SC operations. We constructed an inventory using publicly available datasets from industry, government, and non-governmental sources. We used descriptive statistics and data visualization to sumarize emissions from the US Environmental Protection Agency’s (EPA’s) Toxic Release Inventory (TRI) and EPA’s GHG Reporting Program. We compared population characteristics from US Census block groups (BGs) less than versus greater than 5km of an SC, within counties with a SC. Results: SC operations include: (1) pyrolysis, (2) quenching, (3) compression, cooling, and drying, and (4) fractionation. Major toxic emission sources include furnaces, fugitive emissions, and flaring. We identified 32 SC facilities across five states, with most in the Gulf Coast of Texas and Louisiana. TRI chemicals with the highest self-reported cumulative air-emission volumes from 1987-2019 were: ethylene, propylene, hydrochloric acid, benzene, n-hexane, 1,3-butadiene, ammonia, toluene, vinyl acetate, and methanol. SC facilities emitted >650 million metric tons (carbon dioxide equivalents) of GHGs in total from 2010-2019. We found that 752,465 people live in census BGs within 5km of an SC. BGs closer to SCs had higher proportions of residents who were Black, had non-professional occupations, lower educational attainment, and lower median household income. Conclusion: SC operations have the potential for adverse human health impacts and environmental inequities, underscoring the need for additional research on hazards of petrochemical infrastructure. Keywords: plastics, petroleum

Spatial and temporal predictions of whooping crane (Grus americana) habitat along the US Gulf Coast

AbstractThe challenge of conserving viable habitat while simultaneously predicting how land cover may geographically shift with future climate change has put pressure on ecologists and policy‐makers to develop near‐term (several years to a decade) ecological and geospatial predictions. This is particularly relevant for endangered species as ranges adjust to track a changing climate. The whooping crane is vulnerable to these changes, as the overwintering habitat of a small population is susceptible to climate impacts. This study mapped the historical spatial transformation of crane habitat in and around the Aransas National Wildlife Refuge. A time series of ecological niche models was developed to determine the biotic and abiotic factors correlated with crane presence and track how importance has changed over time. The results from the multitemporal models were used to predict areas along the US Gulf Coast where additional unoccupied habitat may be located for crane population expansion and model how the areas may degrade or change as sea levels rise through future climate change scenarios. Findings indicate that the percentage of emergent herbaceous wetland and water are the most important variables influencing crane presence. Sea level rise analysis indicates that potential habitat throughout the Texas–Louisiana Gulf Coast will be impacted considerably by climate change. The lack of large, continuous blocks of usable land cover could limit population expansion and future recovery efforts. However, the findings can help facilitate winter range expansion to accommodate the growing population by identifying additional areas to protect that could be used by the current wild population or experimental populations.

Leveraging community science data for population assessments during a pandemic.

The COVID-19 pandemic has disrupted field research programs, making conservation and management decision-making more challenging. However, it may be possible to conduct population assessments using integrated models that combine community science data with existing data from structured surveys. We developed a space-time integrated model to characterize spatial and temporal variability in population distribution. We fit our integrated model to 10 years of eBird (2010-2020) and 9 years of aerial survey (2010-2019) Mottled Duck count data to forecast 2020 population size along the western Gulf Coast of Texas and Louisiana. Estimates of Mottled Duck abundance were similar in magnitude to estimates calculated using previous methods but were more precise and showed evidence of a declining population. The spatial distribution for Mottled Ducks each year was characterized by several concentrations of relatively high abundance, although the location of these abundance "hotspots" varied over time. Expected abundance was higher for areas with a higher proportion of area covered by marsh habitat. By leveraging large-scale community science data, we were able to conduct a population assessment despite the disruption in structured surveys caused by the pandemic. As participation in community science platforms continues to increase, we anticipate modeling frameworks, like the integrated model we developed here, will become increasingly useful for informing conservation and management decision-making.

Projected impact of sea-level rise and urbanization on mottled duck (Anas fulvigula) habitat along the Gulf Coast of Louisiana and Texas through 2100

Coastal wetlands along the Gulf of Mexico support a wide diversity of wildlife, are important nurseries for sport and commercial fisheries, provide erosion and flood control, and serve many other ecological functions and services. These marshes have been declining in area and degrading at alarming rates since the 1930s. Effective conservation planning is vital to protect these ecosystems, but decision makers often lack knowledge of expected future conditions to strategically target conservation actions. To address this issue, we focus on a species of conservation concern, the mottled duck (Anas fulvigula), that resides year-round in the coastal marshes of the Gulf of Mexico. We used location data collected from radiomarked hen mottled ducks from 2006 to 2011 to create an ensemble model of habitat selection for 2010. We then projected future habitat states using models of sea-level rise and human development. By combining future predictions with our ensemble model, we predict future habitat for mottled ducks through 2100, in 20-year time steps beginning with 2020. Sea-level rise models predicted reductions in coastal marsh habitats and our ensemble model predict corresponding declines in overall habitat quantity and quality for mottled ducks, with the largest rate of habitat loss predicted within the Chenier Plain of Louisiana, USA at 71%. In some areas, particularly the Texas Mid-Coast, USA, future urbanization and human development is expected to reduce the ability of wetland habitat to migrate inland with rising sea-levels. Our results also highlight areas of coastal marsh particularly vulnerable to sea-level rise; and conversely, identify areas most likely to persist into the future that could be targeted for habitat conservation to help mottled ducks persist on the landscape.

ENDEMIC IN THE PANDEMIC: MURINE TYPHUS MASKING AS COVID-19 PNEUMONIA WITH PROFOUND HYPOXEMIA

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: The presentation of fever, fatigue, myalgias, and acute hypoxemic respiratory failure is COVID-19 viral pneumonia until proven otherwise. However, findings like rash, photophobia, and unexplained lab abnormalities suggest an alternate diagnosis. We present a case of flea-borne (murine) typhus, causing acute illness with increasing prevalence in southern Texas and California. CASE PRESENTATION: In April 2020, a 32-year-old male presented to our emergency department (ED) with one week of fever, headache, progressive dyspnea, myalgias, and flank pain. Five days prior, COVID-19 PCR was negative;he was diagnosed with bilateral pneumonia on CT chest tomography and prescribed azithromycin. In the ED, he was found to be in acute hypoxemic respiratory failure needing high flow oxygen support prompting ICU admission. Vital demonstrated temperature of 103.4 degrees, heart rate of 130, respiratory rate of 26, and Spo2 of 96% oxygen saturation on 10L non-rebreather mask;Physical exam demonstrated dry mucous membranes, conjunctivitis, and labored respirations with accessory muscle use. Labs revealed hyponatremia, elevated liver function tests, hypoalbuminemia, thrombocytopenia, and elevated lactate dehydrogenase and procalcitonin. Repeat CT chest tomography showed posterior lower lobe opacities and concomitant ground glass opacities suggestive of atypical infection. Negative workup included two COVID-19 nasopharyngeal swabs, influenza A/B, RSV, HIV, streptococcus pneumoniae, and legionella urine antigen. He admitted recent travel to the Louisiana Gulf Coast with exposure to horses, chickens, and insect bites on the arm on further questioning. Vancomycin, ceftriaxone, and doxycycline were started on hospital day 2. A papular rash appeared on the lower back on hospital day 6. He still remained febrile and with significant hypoxemia for seven days. On day 9, Rickettsial typhus serologies returned IgM 1:512, and repeat tests confirmed both elevated IgM and IgG. The patient tapered off oxygen and was discharged home on doxycycline. DISCUSSION: Many cases of murine typhus are assumed to be a viral illness, but the clinical triad of fever, headache, and rash in endemic areas must raise suspicion. The exposure was likely insect bites (fleas), although it is not necessary, as endemic typhus has been identified in rural/suburban areas from possums, rats, or cats. In the COVID-19 pandemic, murine typhus with fever and acute hypoxemic respiratory failure was challenging to identify, but early diagnosis and treatment with tetracyclines provided a good outcome. CONCLUSIONS: The presentation of fever, headache, and rash with thrombocytopenia and transaminitis should trigger typhus workup and early treatment, which may otherwise progress to critical illness and death. REFERENCE #1: Afzal Z, Kallumadanda S, Wang F, Hemmige V, Musher D. Acute Febrile Illness and Complications Due to Murine Typhus, Texas, USA1,2. Emerg Infect Dis. 2017;23(8):1268-1273. doi:10.3201/eid2308.161861 REFERENCE #2: van der Vaart TW, van Thiel PP, Juffermans NP, van Vugt M, Geerlings SE, Grobusch MP, Goorhuis A. Severe murine typhus with pulmonary system involvement. Emerg Infect Dis. 2014 Aug;20(8):1375-7. doi: 10.3201/eid2008.131421. PMID: 25062435;PMCID: PMC4111165. DISCLOSURES: No relevant relationships by Philip Lavere, source=Web Response No relevant relationships by Dharani Kumari Narendra, source=Web Response

Common risk segment mapping: Streamlining exploration for carbon storage sites, with application to coastal Texas and Louisiana

Large-scale deployment of Carbon Capture and Storage (CCS) will require a commensurately large number of sites. Efficient screening methods are needed to create investment assurance and focus efforts on the most promising sites. The problem is similar to petroleum exploration, for which there are well-developed (though seldom published) workflows, including Common Risk Segment (CRS) mapping. In brief, the process requires 1) defining the key play elements; 2) identifying candidate geologic intervals for each; 3) creating fact-based maps for those intervals; 4) determining minimum criteria for the success of each element; 5) reinterpreting the fact-based maps in terms of chance of success; and 6) combining the individual maps to form a composite, basin-scale view of prospectivity. In this paper, we adapt the CRS process to screening for CO2 storage sites. Critically, we redefine the process in terms of cost of characterization and development, rather than chance of success. For illustration, we apply the process to the example of the Lower Miocene on the Texas and Louisiana Gulf Coast. We show that the predictions are consistent with historic hydrocarbon production volumes and rates. The power of the CRS method is that it creates a systematic approach to geologic evaluation and translates complex, multidimensional analysis into clear, graphical and easily comprehended business inputs. The result highlights sweet spots and identifies critical risks, suggesting a focus for further data collection and analysis. The method developed here can be applied to both surface and subsurface factors anywhere that there is interest in geologic storage of CO2.

Leveraging scale economies and policy incentives: Carbon capture, utilization & storage in Gulf clusters

Carbon capture, utilization and storage (CCUS) represents a set of technologies essential to meeting ambitious mid-to late-century decarbonization goals. Yet deployment of CCUS has been slow, with fewer than 20 large-scale facilities operating worldwide in 2019. We estimate the total and marginal cost of constructing and operating new CCUS facilities and associated infrastructure to reduce carbon dioxide (CO2) emissions from current and planned industrial facilities on the Texas and Louisiana Gulf Coast. We compare these cost estimates to scheduled CCUS tax incentives through 2026 under section 45Q of the U.S. Internal Revenue Code to quantify cost-effective emissions abatement. Our analysis measures the cost-reducing potential of economies of scale in regional CO2 pipeline networks. We also compare CCUS costs to one measure of the benefits of carbon capture, the social cost of carbon. Results suggest that U.S. federal tax incentives currently in place through 2026 could justify between 3.3 million and 77.6 million tons of annual CCUS in the Gulf region, depending on the choice of storage technology and the degree of pipeline network coordination. Finally, we highlight several potential policy barriers that may explain low adoption of CCUS in the Gulf Region and elsewhere.

Sea-level rise enhances carbon accumulation in United States tidal wetlands

Sea-level rise enhances carbon accumulation in United States tidal wetlands

Jean Laffite: Piracy and the limits of state power in New Orleans, 1814-1815

The pirate, privateer and smuggler Jean Laffite dominated the mercantile life of New Orleans from 1809 to 1815 by exploiting the limited reach of a weak US government in its attempts to control over the frontier of the Louisiana Gulf Coast. Laffite’s status as a cultural anti-hero to the majority-French population, who disdained the American government and the war it initiated in 1812, saw much public support for his efforts to evade law enforcement. Such support, however, waned in the face of an overwhelming threat from British invaders in the autumn of 1814. Adept at survival, Laffite reinvented himself as a loyal patriot by contributing vital materiel to the shaky military defence of the city. In doing so, he ensured his freedom and became a hero of the Battle of New Orleans, a myth that endures to this day. His story demonstrates the limits of state power against piratical practices in the nineteenth century, particularly when they occurred on a distant shore, among a population who protected their cherished rogues.

Deepwater Horizon oil spill exposure and child health: a longitudinal analysis

The BP Deepwater Horizon oil spill (DHOS) created widespread concern about threats to health among residents of the Louisiana Gulf Coast. This study uses data from the Resilient Children, Youth, and Communities study—a longitudinal cohort survey of households with children in DHOS-affected areas of South Louisiana—to consider the effect of DHOS exposure on health trajectories of children, an especially vulnerable population subgroup. Results from latent linear growth curve models show that family DHOS exposure via physical contact and job/income loss both negatively influenced initial child health. However, the effects of physical exposure dissipated over time while the effects of job/income loss persisted. This pattern holds for both general child health and the number of recent physical health problems children had experienced. These findings help to bridge the literature on disaster impacts and resilience/vulnerability, with the literature on socioeconomic status as a fundamental cause of health outcomes over the life course.

Gulf Coast tales

Gulf Coast tales Jillian Brenner (bio) Moon Trees and Other Orphans Leigh Camacho Rourks Black Lawerence Press www.blacklawrence.com/moon-trees-and-other-orphans/ 175 Pages; Print, $15.95 Moon Trees and Other Orphans is the debut collection of Cuban American writer Leigh Camacho Rourks and a winner of the St. Lawrence Book Award. The collection is set along the Gulf Coast, where the natural beauty of the environment and the fragility of characters suffering with sickness, poverty, and mental illness combine with the harshness of their reality, resulting in unforgettable stories of impossible strength in impossible places. Camacho Rourks does not shy away from pushing her characters to their limits and examining the fallout as they break, with a style that invites both comedic commentary and sobering realizations about what it means to be disenfranchised in the South. Of the array of memorable and nuanced characters, the most remarkable of them all is perhaps the setting itself. With a characterization of place reminiscent of Flannery O’Connor’s writings of the South, Camacho Rourks brings the Gulf Coast of Louisiana to life. Though each story varies in plot and detail, the theme of hard-shelled characters nursing weaknesses — often hidden behind a veneer of wit and sarcasm — and pushing through brutal circumstances is consistent in the collection. These characters fall, they make bad decisions, and they seem very much alive. The titular story, “Moon Trees,” follows Essie and her brother, Stute, as Essie struggles to provide a stable home in the midst of their mother’s struggle with paranoid schizophrenia. Essie, a teenager, shows her mother a culmination of kindness, love, pity, and rage as Essie narrates the “myths” of their family’s history. The title comes from the family’s fascination with a 1970’s space mission, in which Stuart Roosa took an “unborn forest” into orbit before returning to plant the seeds on earth. Though the basic plot is not new, the narrative style brings a freshness and originality to the story. The commentary on the stigmas of mental illness, the difficulty of finding adequate treatment, and the failure of inequal access to education for children in low income homes is there, but they work as the subtext of the narrative. Instead, Comacho Rourks asks her readers to consider what it means to be special or how far the strands of family can be pulled before they break. Though setting is not as prevalent here as other stories, details of New Orleans and a secret “moon tree” along the River Walk are woven in. Comacho Rourks’s writing is well paced and concise, yet, despite the harshness of her subjects, inarguably beautiful. One such example is Essie’s description of her mother’s story of finding one of Roosa’s seeds and her mother’s belief that her subsequent pregnancy with Essie resulted in her illness: I can tell you how one day, when she was very lonely, she gobbled that seed up to make me. When I was a child, I did not fall asleep to Cinderella’s broom strokes and ballroom dancing. Instead, my mother told me of how her white fish-belly, iridescent with life, grew heavy and catered with my weight. I branched out inside of her, and my fetal limbs, long and searching, pierced her brain and left her addled. While “Moon Trees” is the collection’s ode to character, “Pinched Magnolias” is among the best at juxtaposing Louisiana swampland as both hero and villain. By the end of the second page, Dalia — a clear image of femininity at a height of five feet and wearing a floral sundress — has started her day by shooting her husband and then making a pot of coffee. Dalia and her sister, the sheriff, grew up on a large property alongside the bayou, where they learned to skin animals from their loving father whose murdered corpse was found in the swamp years before. The women speak to each other calmly as they dismantle the body of Dalia’s husband to be dumped for alligators. Dalia and Mary are both as much products of their environment as they are bound to it...

Influence of Land Cover and Soil Moisture based Brown Ocean Effect on an Extreme Rainfall Event from a Louisiana Gulf Coast Tropical System

Extreme flooding over southern Louisiana in mid-August of 2016 resulted from an unusual tropical low that formed and intensified over land. We used numerical experiments to highlight the role of the ‘Brown Ocean’ effect (where saturated soils function similar to a warm ocean surface) on intensification and it’s modulation by land cover change. A numerical modeling experiment that successfully captured the flood event (control) was modified to alter moisture availability by converting wetlands to open water, wet croplands, and dry croplands. Storm evolution in the control experiment with wet antecedent soils most resembles tropical lows that form and intensify over oceans. Irrespective of soil moisture conditions, conversion of wetlands to croplands reduced storm intensity, and also, non-saturated soils reduced rain by 20% and caused shorter durations of high intensity wind conditions. Developing agricultural croplands and more so restoring wetlands and not converting them into open water can impede intensification of tropical systems that affect the area.

Lignin chemistry of wetland soil profiles in two contrasting basins of the Louisiana Gulf coast

Recent studies indicate that loss of soil organic matter (SOM) from coastal wetlands can contribute to the hypoxia in the northern Gulf of Mexico along the Louisiana coast. In this study, coastal marsh soil profiles of two contrasting basins were investigated for lignin composition in order to assess organic matter source and degradation status under these different wetland formations. The Atchafalaya Basin is undergoing land building whereas the Barataria Basin is experiencing land loss. Lignin monomers were extracted using alkaline CuO oxidation followed by gas chromatography–mass spectrometry characterization. Marsh soil profiles from the Barataria Basin showed strong lignin storage with two-fold higher lignin contents (sum of vanillyl, syringyl, and cinnamyl phenols, Λ8) than those in the Atchafalaya Basin. Source SOM inputs in the Barataria Basin were non-woody angiosperms, whereas in the Atchafalaya Basin inputs were non-woody angiosperms and some gymnosperm inputs. Principal component analysis (PCA) showed that different soil environmental factors dominated the status of soil organic matter degradation. Soil pH was negatively related to the lignin degradation in the Atchafalaya Basin, whereas high total N contents inhibited lignin degradation in the Barataria Basin. Increasing electrical conductivity inhibited organic matter degradation in the low salinity wetlands of the Atchafalaya Basin, but positively influenced lignin decomposition in the higher salinity marsh soil profiles of Barataria Basin. Despite SOM in the Barataria Basin being more degraded than in the Atchafalaya, the nearly 10-fold greater amount of organic carbon (C) in the Barataria, coupled with net land loss, indicates that it is greater source of oxygen-consuming organic C, thus contributes more to the hypoxia in the Gulf.

When disasters strike environmental science: a case\u2013control study of changes in scientific collaboration networks

Studies of scientific collaboration networks reveal the social structure of scientific disciplines. Most of these studies assume scientists work under conditions of institutional stability. What happens to science when disaster strikes and research practice is disrupted? This study examines structural changes in a scientific collaboration network after serial exposure to major disasters. We analyze the collaboration network of wetlands scientists publishing research related to the marshes of the Louisiana Gulf Coast between 1996 and 2015, along with a control network from a wetlands setting in a different geographic area that did not experience any disasters over the same time span. Hurricanes Katrina and Rita (2005) and the Deepwater Horizon oil spill (2010) offer the opportunity to compare the Gulf wetlands collaboration network before and after the disasters. Results indicate changes in size, research activity, and connectivity in periods following the major hurricanes and oil spill.

Synergistic Effects of Temperature and Salinity on the Gene Expression and Physiology of Crassostrea virginica.

The eastern oyster, Crassostrea virginica, forms reefs that provide critical services to the surrounding ecosystem. These reefs are at risk from climate change, in part because altered rainfall patterns may amplify local fluctuations in salinity, impacting oyster recruitment, survival, and growth. As in other marine organisms, warming water temperatures might interact with these changes in salinity to synergistically influence oyster physiology. In this study, we used comparative transcriptomics, measurements of physiology, and a field assessment to investigate what phenotypic changes C. virginica uses to cope with combined temperature and salinity stress in the Gulf of Mexico. Oysters from a historically low salinity site (Sister Lake, LA) were exposed to fully crossed temperature (20°C and 30°C) and salinity (25, 15, and 7 PSU) treatments. Using comparative transcriptomics on oyster gill tissue, we identified a greater number of genes that were differentially expressed (DE) in response to low salinity at warmer temperatures. Functional enrichment analysis showed low overlap between genes DE in response to thermal stress compared with hypoosmotic stress and identified enrichment for gene ontologies associated with cell adhesion, transmembrane transport, and microtubule-based process. Experiments also showed that oysters changed their physiology at elevated temperatures and lowered salinity, with significantly increased respiration rates between 20°C and 30°C. However, despite the higher energetic demands, oysters did not increase their feeding rate. To investigate transcriptional differences between populations in situ, we collected gill tissue from three locations and two time points across the Louisiana Gulf coast and used quantitative PCR to measure the expression levels of seven target genes. We found an upregulation of genes that function in osmolyte transport, oxidative stress mediation, apoptosis, and protein synthesis at our low salinity site and sampling time point. In summary, oysters altered their phenotype more in response to low salinity at higher temperatures as evidenced by a higher number of DE genes during laboratory exposure, increased respiration (higher energetic demands), and in situ differential expression by season and location. These synergistic effects of hypoosmotic stress and increased temperature suggest that climate change will exacerbate the negative effects of low salinity exposure on eastern oysters.

Modeling and predicting fecal coliform bacteria levels in oyster harvest waters along Louisiana Gulf coast

Fecal coliform bacteria are important indicator microorganisms that are commonly monitored monthly for the quality of oyster harvest waters and the end product, making the protection of public health challenging as oyster harvest may occur daily and fecal coliform levels in oyster harvest waters may also change daily. This paper presents an artificial intelligence-based neural network modeling approach to predict fecal coliform bacteria levels in oyster harvest areas (waters) daily. The new approach was demonstrated by developing an artificial neural network (ANN) model for daily prediction of fecal coliform levels in seven oyster harvest areas along the Northern Gulf of Mexico coast. The model input variables were selected by using the stepwise regression analysis method. It was found that the prevalence of fecal coliform bacteria in oyster growing waters was controlled by six independent environmental predictors, including wind, salinity, tide, water temperature, rainfall, and solar radiation, which were utilized as the model input variables. It was also found that the prevalence of fecal coliform bacteria in oyster growing waters is affected by not only current conditions of the six independent environmental variables but also antecedent conditions of the variables (particularly average solar radiation and cumulative rainfall over the past two days). Model prediction results indicated that the ANN model was capable to predict not only daily variations in fecal coliform levels but also seasonal fluctuations in observed fecal coliform levels characterized by high bacteria levels in the cold season and low bacteria levels in the warm season. The performance of the ANN model was demonstrated by the linear correlation coefficient (LCC) of 0.7421 and root mean square (RMSE) of 0.3844 for the model development phase and the LCC of 0.6312 and RMSE of 0.2835 for the independent validation phase. The ANN model makes it possible to reduce the harvest and consumption of fecally contaminated oysters and thereby greatly reduce the health risk to the general public and particularly oyster consumers. Although the predictive ANN model was specifically developed for oyster harvest areas along the Louisiana Gulf coast, the methods used in this paper are generally applicable to other oyster harvest areas and coastal waters.

Assessment of Shorebird Migratory Fueling Physiology and Departure Timing in Relation to Polycyclic Aromatic Hydrocarbon Contamination in the Gulf of Mexico.

Shorebirds depend on staging sites in the Gulf of Mexico that are frequently subject to pollution by oil and its toxic constituents, polycyclic aromatic hydrocarbons (PAHs). It was hypothesized that PAH contamination lowers staging site quality for migratory shorebirds, with consequences for fueling and departure timing. Sediment total PAH concentrations were measured at six staging sites along the Texas and Louisiana Gulf Coast. Sites in Louisiana were expected to have higher total PAH concentrations as they were more heavily impacted by the Deepwater Horizon oil spill. From 2015 to 2017, 165 Sanderling ( Calidris alba) and 55 Red knots ( C. canutus) were captured at these same sites during their northward migration (late April to mid May). Mass, body morphometrics, and plasma metabolite measurements were taken to determine fuel loads and fueling rates, and a subset of birds (120 Sanderling and 39 Red knots) received a coded radio tag to determine departure dates using the Motus telemetry array. Compared to Texas sites, sediment in Louisiana had higher total PAH concentrations, dominated by heavier 6 ring indeno[1,2,3- cd]pyrene (48%). Plasma metabolite profiles suggested that fueling rates for Sanderling, but not Red knots, tended to be lower in Louisiana, and both species departed later than the study average from Louisiana. However, multiple factors, including migration patterns, food supply, and other contaminants, also likely influenced fueling and departures. PAH contamination in the Gulf of Mexico remains an ongoing issue that may be impacting the staging site quality and migration timing of long-distance migratory birds.

Disconnects in Megaregional Freight Planning Are Holding Back the Louisiana Gulf Coast

The megaregion has emerged as the preferred unit of analysis for freight transportation and global trade. In the United States, trade and transportation barriers of state boundaries can impede the formation of megaregions, resulting in the hampering of economic development. As a preliminary investigation of the Gulf Coast megaregion, we performed a content analysis of the relationship between freight-related themes in the comprehensive and long-range plans for the metropolitan areas and the respective 11 parishes (counties) in southeastern Louisiana. Our results indicated a slight correlation between freight transportation infrastructure resources and theme frequencies in the histograms, but an overall lack of planning focus on freight infrastructure or trade capacities throughout the study area. Although freight transportation is becoming important federally, Louisiana state and local governments do not fully plan for it, leading to outdated transportation systems, inefficiency, and congestion.