Gulf of Mexico Research Papers (original) (raw)

This paper describes the successful application of amplitude-versus-angle ͑AVA͒ inversion of prestack-seismic amplitude data to detect and delineate deepwater hydrocarbon reservoirs in the central Gulf of Mexico. Detailed AVA fluid/ lithology sensitivity analysis was conducted to assess the nature of AVA effects in the study area based on well-log data. Standard techniques such as crossplot analysis, Biot-Gassmann fluid substitution, AVA reflectivity modeling, and numerical simulation of synthetic gathers were part of the AVA sensitivity analysis.

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- Geophysics, Sensitivity Analysis, Gulf of Mexico

One of the critical information needs identified at the 2003 Deep-Sea Corals Workshop in Galway, Ireland, was to locate and chart deep-sea corals in order to develop reliable estimates of their distribution and abundance. While reports of deep-sea corals from the Gulf of Mexico date back to the 1860s, relatively little is known about their distribution or abundance. This paper attempts to provide a current assessment of the occurrence of Lophelia pertusa and Madrepora oculata in water depths greater than 200 m in the Gulf of Mexico by summarizing records from (1) published material, (2) the 2003 National Museum of Natural History Taxonomic Database, (3) findings obtained during the September-October 2003 NOAA-OE RV Ronald H. Brown cruise RB-03-07-leg-2 in the northern Gulf, and (4) from various unpublished sources.

- by Julie Olson
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- Natural History, Gulf of Mexico, Deep water, Cold-Water Corals

The algal-derived compound dimethylsulfoniopropionate (DMSP), which is the precursor of the climatically active gas dimethylsulfide, is potentially an important source of carbon and sulfur to marine bacterioplankton. Currently, bacteria of the Roseobacter clade, a subgroup of ␣-proteobacteria, are hypothesized to be the key participants in the metabolism of DMSP. To test this hypothesis, we used a combination of microautoradiography and fluorescence in situ hybridization (Micro-FISH) to identify the bacteria assimilating 35 S DMSP in the Gulf of Mexico, the Gulf of Maine, and the Sargasso Sea. On average, half of the bacterial community assimilated DMSP in these environments. Members of the ␣-proteobacteria dominated DMSP assimilation, accounting for 35-40% of bacteria assimilating DMSP. Cytophaga-like bacteria and ␥-proteobacteria each accounted for 15-30% of DMSP-assimilating cells. The ␣-proteobacteria accounted for a greater fraction of the DMSP-assimilating community than expected based on their overall abundance, whereas Cytophaga-like bacteria were typically underrepresented in the DMSP-assimilating community. Members of the Roseobacter clade assimilated more DMSP on a per-cell basis than any other group, but they did not account for most of the DMSP assimilation, nor were they always present even when DMSP turnover was high. These results indicate that the biogeochemical flux of dissolved DMSP is mediated by a large and diverse group of heterotrophic bacteria.

- by David Kirchman
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- Earth Sciences, Biological Sciences, Environmental Sciences, North Atlantic

The Alligator Snapping Turtle (Macrochelys temminckii) is a large freshwater turtle endemic to river systems that drain into the Gulf of Mexico. Turtle populations were sharply reduced by commercial harvest in the 1970s and 1980s; however, the species has yet to be protected under the Endangered Species Act. While anthropogenic stressors such as habitat fragmentation and degradation and illegal capture continue to threaten populations, the degree to which disease may be contributing to any decline of the Alligator Snapping Turtle is unknown. Data were collected from 97 free-ranging Alligator Snapping Turtles in nine waterways in Florida and Georgia from 2001 to 2006. Eleven turtles were captured more than once, resulting in a total sample pool of 123. Reference ranges were established for complete blood count, plasma biochemistry values, trace metals (mercury, zinc, copper, lead, and arsenic), and nutrient parameters (vitamins A, E, D, and selenium). Variations by capture location, sex, and season were detected and likely resulted from external factors such as habitat and diet. Turtles sampled in one location were positive for tortoise herpesviral antibodies. Blood mercury values also differed among populations. This study provides justification for the use of these long-lived aquatic turtles as biologic monitors of the health of local freshwater ecosystems.

- by Terry Norton
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- Arsenic, Trace Metals, Georgia, Seasonality

A dual-channel microwave radiometer that measures precipitable water vapor and cloud liquid was operated during the 1979 Severe Storms and Mesoscale Experiment (Sesame). Conventional retrievals of vapor in the presence of clouds with high liquid content were not satisfactory. To correct these retrievals, an adaptive retrieval algorithm is developed and applied to the Sesame data. During clear conditions, or conditions of light clouds, the new recoveries are quite close to those obtained by conventional statistical inversion; however, during heavy liquid-bearing clouds the recovered vapor agrees better with radiosonde data.

- by E. Westwater
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- Multidisciplinary, Gulf of Mexico, Microwave radiometer, Precipitable Water Vapor

An 8-year database of sea surface temperature (SST), 7 years of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color images, wind fields, and numerical model results are analyzed to identify regions and periods of coastal upwelling... more

- by Jorge Zavala-hidalgo and +1
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- Geology, Oceanography, Sea surface temperature, Seasonality

We recorded high-resolution seismic-reflection data in the northern Gulf of Mexico to study gas and gas-hydrate distribution and their relation to seafloor slides. Gas hydrate is widely reported near the seafloor, but is described at only one deep drill site. Our data show highreflectivity zones (HRZs) near faults, diapirs, and gas vents and interbedded within sedimentary sections at shallow depth (, 1 km). The HRZs lie below the gas-hydrate-stability zone (GHSZ) as well as within the zone (less common), and they coincide with zones of shallow water-flows. Bottom simulating reflections are rare in the Gulf, and not documented in our data. We infer HRZs result largely from free gas in sandy beds, with gas hydrate within the GHSZ. Our estimates for the base BHSZ correlate reasonably with the top of HRZs in some thick well-layered basin sections, but poorly where shallow sediments are thin and strongly deformed. The equivocal correlation results from large natural variability of parameters that are used to calculate the base of the GHSZ. The HRZs may, however, be potential indicators of nearby gas hydrate. The HRZs also lie at the base of at least two large seafloor slides (e.g. up to 250 km 2) that may be actively moving along decollement faults that sole within the GHSZ or close to the estimated base of the GHSZ. We suspect that water/gas flow along these and other faults such as 'chimney' features provide gas to permit crystallization of gas hydrate in the GHSZ. Such flows weaken sediment that slide down salt-oversteepened slopes when triggered by earthquakes. Published by Elsevier Science Ltd.

- by Patrick Hart
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- Geology, Geophysics, Gas Hydrate, Salt diapir

The link between the Pacific/North American pattern (PNA) and the North Atlantic Oscillation (NAO) is investigated in reanalysis data (NCEP, ERA40) and multi-century CGCM runs for present day climate using three versions of the ECHAM model. PNA and NAO patterns and indices are determined via rotated principal component analysis on monthly mean 500 hPa geopotential height fields using the varimax criteria.

- by Joaquim Pinto and +1
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- Oceanography, Principal Component Analysis, North Eastern North America Archaeology, North Atlantic Oscillation

We examined a suite of paleoindicators in 210 Pb-dated sediment cores to determine the historical course of primary production, eutrophication, and oxygen stress in the coastal ocean adjacent to the plumes of the Mississippi and Atchafalaya rivers. The assumption that hypoxia is a natural feature of the coastal ecosystem in the northern Gulf of Mexico influenced by the discharge of the Mississippi River system is not supported by paleoindicators in accumulated sediments. There is a propensity for the ecosystem to develop hypoxia because of the high discharge of the Mississippi River and physical dynamics on the continental shelf that support stratification. However, paleoindicators of eutrophication and oxygen conditions record recent anthropogenic influences. The evidence for increased carbon production and accumulation comes from diatoms and their remnants, marine-origin carbon in the sediments, and phytoplankton pigments. Surrogates for oxygen condition, including mineral, isotopic, microfossil, and phytoplankton pigment indicators, indicate worsening oxygen stress. The changes are more apparent in areas of present chronic hypoxia and are coincident with the increasing nitrogen loads from the Mississippi River system beginning in the 1950s. Longer-term shifts in offshore ecology parallel landscape changes within the watershed in the last two centuries. The temporal shifts in this coastal ecosystem parallel the time sequence of similarly eutrophied coastal waters globally and coincide nicely with sediment analyses from other locations.

- by Michael Parsons
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- Biological Sciences, Environmental Sciences, Ecological, Gulf of Mexico

This paper describes the linkage of a three-dimensional hydrodynamic circulation model with descriptive and experimental biological data concerning oyster (Crassostrea virginica) population dynamics in the Apalachicola Estuary (Florida, U.S.A.). Our intent was to determine the direct and indirect role of Apalachicola River flow in the maintenance of oyster production. Results of a monthly field sampling programme conducted on the oyster reefs in the Apalachicola system during 1985-1986 were used to develop statistical models relating several life-history characteristics of oysters to physical-chemical aspects of water quality. The same life-history characteristics were related statistically to output from a circulation model of Apalachicola Bay. Highest oyster densities and overall bar growth were found in the vicinity of the confluence of high salinity water moving westwards from St George Sound and river-dominated (low salinity) water moving south and eastwards from East Bay. With the exception of models for oyster mortality, the predictive capability of results from the parallel modelling efforts was low. A time-averaged model was developed for oyster mortality during the summer of 1985 by running a regression analysis with averaged predictors derived from the hydrodynamic model and observed (experimental) mortality rates throughout the estuary. A geographic information system was then used to depict the results spatially and to compare the extent of expected mortality in 1985 and 1986. High salinity, relatively low-velocity current patterns, and the proximity of a given oyster bar to entry points of saline Gulf water into the bay were important factors that contribute to increased oyster mortality. Mortality was a major determinant of oyster production in the Apalachicola Estuary with predation as a significant aspect of such mortality. By influencing salinity levels and current patterns throughout the bay, the Apalachicola River was important in controlling such mortality. Oyster production rates in the Apalachicola system depend on a combination of variables that are directly and indirectly associated with freshwater input as modified by wind, tidal factors, and the physiography of the bay. River flow reduction, whether through naturally occurring droughts, through increased upstream anthropogenous (consumptive) water use, or a combination of the two, could have serious adverse consequences for oyster populations. By coupling hydrodynamic modelling with descriptive and experimental biological data, we were able to determine the effects of potential freshwater diversions on oyster production in Apalachicola Bay.

- by Mark Monaco
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- Earth Sciences, Life history, Biological Sciences, Environmental Sciences

A Spatio-Temporal Analysis of Dolphinfish; Coryphaena (August 2008) Hippurus, Abundance in the Western Atlantic: Implications for Stock Assessment of a Data-Limited Pelagic Resource. Abstract of a dissertation at the University of Miami. Dissertation supervised by Professor David Die. No. of pages in text. (331) Dolphinfish (Coryphaena hippurus) is a pelagic species that is ecologically and commercially important in the western Atlantic region. This species has been linked to dominant oceanographic features such as sea surface temperature (SST) frontal regions.

Dimethylsulfoniopropionate (DMSP) is produced by marine algae and released during foraging activity by zooplankton and fish. Pelagic fishes depend on patchily distributed foraging opportunities, and DMSP may be an important signaling molecule for these events. We have previously shown that the abundance of carangid jacks is positively associated with elevated DMSP levels over coral reefs in the Gulf of Mexico, suggesting that these fishes may use spatial and temporal variation in DMSP to locate foraging opportunities. Here, we extend this work by demonstrating that juveniles of two species of pelagic jack, crevalle jack, Caranx hippos, and bluefin trevally, C. melampygus, detect and respond to DMSP in a flow-through tank in the laboratory. Juveniles of these species showed elevated swimming activity in response to ecologically relevant concentrations of DMSP (10−9 M). These results provide further evidence that this chemical may serve as a chemosensory cue for carangid species.

- by Jennifer DeBose and +1
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- Entomology, Animal Behavior, Behavior, Chemical Ecology

Marine humic and fulvic acids were concentrated from about 1,400 liters of seawater from the Gulf of Mexico, and specific absorption coefficients were measured for each from 240 to 675 nm. Spectral absorption coefficients were then calculated for Gulf of Mexico stations where earlier data on humic and fulvic acid concentrations were available. Marine humic and fulvic acid values have

- by Robert Steward
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- Remote Sensing, Humic acid, Fulvic acid, Gulf of Mexico

Seven sea anemone species from coral reefs in the southern Gulf of Mexico are taxonomically diagnosed
and images from living specimens including external and internal features, and cnidae are provided. Furthermore,
the known distribution ranges from another 10 species are extended. No species records of sea
anemones have been previously published in the primary scientific literature for coral reefs in the southern
Gulf of Mexico and thus, this study represents the first inventory for the local actiniarian fauna.

- by Ricardo Gonzalez and +1
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- Coral Reefs, Marine biodiversity, Biodiversity, Cnidaria

An ecological and hydrologic restoration of the Mississippi-Ohio-Missouri (MOM) Basin in the United States is proposed as the solution to the reccurring hypoxic conditions in the Gulf of Mexico. Nitrate-nitrogen is the cause of this eutrophication in the Gulf and its source is mainly due to increased fertilizer use in the American Midwest. In that same Midwest, the land has also been artificially drained and 80-90% of the original wetlands have been lost. Our proposed restoration involves the strategic creation and restoration of 2.2 million ha of wetlands in the MOM basin where in-field wetlands intercept agricultural runoff and diversion wetlands are overflowed by flooding river water. Case studies that total 50 wetland-years of data from Illinois, Ohio, and Louisiana are summarized as the basis for the restoration area estimate. Benefits of this restoration, in addition to solving the Gulf hypoxia, include water quality improvement, reduction of public health threats, habitat creation, and flood mitigation that will accrue to the locations in the MOM basin where the restoration occurs. Before the restoration commences, there is a need for formal and rigorous large-scale research in the basin to reduce uncertainties. (W.J. Mitsch).

- by William J Mitsch
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- Engineering, Ecological Engineering, Earth Sciences, Water quality

The Antillean manatee (Trichechus manatus manatus) is considered endangered in Mexico. Local extinctions have been documented in the northern Gulf of Mexico, and the only remaining population with a northern distribution is found in the Alvarado Lagoon System (ALS). The objective of this study was to determine manatee distribution in ALS. The system covers an area of 267,010 ha and includes hundreds of lagoons, floodable areas, and dozens of rivers. To detect manatees, systematic line transects were done in a boat 7.6 m in length, totaling 332.6 h of search effort with an average of 7.38 h d–1 in 45 surveys. There was a total of 13 manatee sightings: seven direct sightings, five with hydrophones, and one with a side-scan sonar. For each record the geographical coordinates were taken and integrated in a geographical information system to analyze their distribution. Manatee distribution was not uniform throughout the study area. Manatees were sighted in very specific areas of ALS cons...

- by Arturo Serrano
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- Marine Biology, Geography, Conservation Biology, Marine Ecology

. White spot syndrome virus WSSV is one of the most important pathogens of penaeid shrimp. It is widely distributed in most Asian countries where penaeid shrimp are cultured, as well as in the Gulf of Mexico and SE USA. The virulence of six geographic isolates of WSSV was compared using Litopenaeus Õannamei postlarvae and Farfantepenaeus duorarum juveniles. The six geographic isolates of WSSV originated from China, India, Thailand, Texas, South Carolina, as well as from crayfish maintained at the USA National Zoo. For challenge studies, virus infected tissues were given per os to L. Õannamei postlarvae and Fa. duorarum juveniles. Resultant WSSV infections were confirmed by histological examination. The cumulative mortality of L. Õannamei postlarvae reached 100% after challenge with each of the six geographic isolates of WSSV. However, the Texas isolate caused mortalities more rapidly than did the other shrimp isolates; the crayfish WSSV isolate was the slowest. In marked contrast, cumulative mortalities of juvenile Fa. duorarum reached only 35-60%, and varied among the geographic isolates of WSSV. Interestingly, in Fa. duorarum, the Texas WSSV isolate was also the most virulent, while the crayfish WSSV was the least virulent. The findings suggest that slight differences in virulence exist among geographic isolates of WSSV, and that susceptibility may vary with species and lifestages of the host. q 0044-8486r99r$ -see front matter q 1999 Elsevier Science B.V. All rights reserved.

- by Rita Redman
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- Zoology, Aquaculture, Virulence, South Carolina

Efforts to understand and preserve the seep communities of the deep Gulf of Mexico (GOM) begin with a comprehensive survey of the biodiversity of these communities. Previous studies have provided a conceptual model of the physiology, population, and community ecology of upper continental slope seeps. However, seeps at water depths below 1000 m in the Gulf of Mexico remain relatively unknown. In this study, data from 47 samples of tubeworm-and mussel-associated communities at depths of 1005-2750 m are examined. Other than tubeworms and mussels, 66 taxa of macro-and megafauna were collected, 43 of which appear to be restricted to water depths of over 1000 m, and 39 that have not been reported previously from the Gulf of Mexico. Diversity in mussel beds was highest at mid-slope depths, but tubeworm-associated communities did not show clear bathymetric trends in diversity. Diversity was higher in tubeworm aggregations at the alpha level (per sample), but higher in mussel beds at the beta level (species turnover among collections). Although both community types were often numerically dominated by the endemic shrimp Alvinocaris muricola, broad differences in the communities hosted by tubeworm aggregations and mussel beds were apparent. The most important factors explaining community similarity within community type were the depth, relative abundance of different mussel species in a bed, and the average size of tubeworms in an aggregation. The high proportion of deep-seep species that were found for the first time in the Gulf of Mexico emphasizes the importance of conservation efforts for these patchy communities.

- by Erik Cordes
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- Geochemistry, Oceanography, Community Ecology, Ecology

* 2. If the corresponding P-value is less than a pre-determinedα , the X variable is added. 3. Assume X7 is the variable added in step 1, the stepwise regression routine now fits next regression model with two X variables, where X7 is one... more

- by Fathi Boukadi
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- Applied Research, Neural Network, Construction Cost, Cost effectiveness

Objective: To identify reasons for air medical evacuations from oil rigs/platforms. Methods: Retrospective review of data of medical calls from 102 rigs/platforms in the US Gulf Coast from 2008 through 2012 with specific analysis of medevacs. Results: On average, 1609 total calls per year relating to illness or injury on the 102 oil rigs/platforms with 4% to 7% requiring medical air evacuation. On average, 77% of medevacs were for nonoccupational medical injury or illness. Conclusions: Illness, not occupational injuries, is identified as the major reason for medical evacuations from oil rigs. Heart disease is the leading cause of chronic health conditions resulting in a medevac.

- by Doris Konicki
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- Nursing, Workplace, United States, Gulf of Mexico

Near-bed hydrodynamic conditions were recorded for almost one year in the Viosca Knoll area (lease block 826), one of the most well-developed cold-water coral habitats in the Gulf of Mexico. Here, a reef-like cold-water coral ecosystem, dominated by the coral Lophelia pertusa, resembles coral habitats found off the southeastern US coast and the North East Atlantic. Two landers were deployed

- by Harvey Seim
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- Geochemistry, Oceanography, Food supply, Mississippi River

A B S T R A C T The purpose of this article is to present the Mexican experience related to the US-Mexico joint Gulf of Mexico Large Marine Ecosystem-Based Assessment and Management Project, particularly the community involvement and mangrove wetland restoration, and the challenges for its replication and up-scaling. Results focus on community engagement, environmental education and social participation, strategies for hydrological restoration of mangrove, and difficulties and recommendations for the implementation of the Strategic Action Program. The main conclusions are that the community-based hydrologic restoration approach, is a good way to ensure long-term restoration of wetlands. Changing from mangrove plantations to the hydrological restoration of wetlands, and construction of human capacities resulted in a more efficient strategy for ecosystem restoration and had influenced the forest environmental policy. The involvement of government and education institutions as execution agencies will contribute to a more efficient appropriation of the project and LME approach. The development of economic alternatives and the ecological monitoring are some of the identified challenges within the implementation phase of the Strategic Action Program.

Gracilaria cornea and G. crassissima are similar species that coexist at Bajo Pepito in the Mexican Caribbean. Differences in agar properties from both species were determined for two reproductive categories: carposporic and undetermined, the latter mainly composed of tetrasporophytes. Agar yield (AY), agar gel strength (GS), 3,6-anhydrogalactose content (AG) and sulfate content (S) of native and alkali-treated agar were determined for both reproductive categories. Significant differences in native and alkali-treated agar between the reproductive categories were recorded for AY, GS and S from G. cornea and G. crassissima, as well as for AG of native agar from the latter species. Our results, and previous studies, demonstrate that neither reproductive stage was predominant over the other(s) in terms of having greater or lower values of agar properties. The potential economic use of agar differences from plants of different reproductive stage remains very limited. Lower AY and GS were...

- by Julio Espinoza-Avalos
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- Caribou, Gulf of Mexico, Yucatan Peninsula, Seasonal change

This is an unpublished essay that I circulated privately in September 2005, several weeks after Hurricane Katrina struck the City of New Orleans. Having lived in the Big Easy while in college and having made it and its culture and its people an important part of my life, I was aghast at calls by people unfamiliar with the city to allow for its demise. This was before it became known to the country that the reason that the city was devastated was the failure of its levees to hold and protect the city and not because of many other factors.

- by Christopher Eck
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- Cultural History, Cultural Heritage, Hurricanes, Culture Studies

1] A method for the inversion of hyperspectral remote sensing was developed to determine the absorption coefficient for chromophoric dissolved organic matter (CDOM) in the Mississippi and Atchafalaya river plume regions and the northern Gulf of Mexico, where water types vary from Case 1 to turbid Case 2. Above-surface hyperspectral remote sensing data were measured by a ship-mounted spectroradiometer and then used to estimate CDOM. Simultaneously, water absorption and attenuation coefficients, CDOM and chlorophyll fluorescence, turbidities, and other related water properties were also measured at very high resolution (0.5-2 m) using in situ, underwater, and flow-through (shipboard, pumped) optical sensors. We separate a g , the absorption coefficient a of CDOM, from a dg (a of CDOM and nonalgal particles) based on two absorptionbackscattering relationships. The first is between a d (a of nonalgal particles) and b bp (total particulate backscattering coefficient), and the second is between a p (a of total particles) and b bp . These two relationships are referred as a d -based and a p -based methods, respectively. Consequently, based on Lee's quasi-analytical algorithm (QAA), we developed the so-called Extended Quasi-Analytical Algorithm (QAA-E) to decompose a dg , using both a d -based and a p -based methods. The absorption-backscattering relationships and the QAA-E were tested using synthetic and in situ data from the International Ocean-Colour Coordinating Group (IOCCG) as well as our own field data.

- by Qian Yu
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- Remote Sensing, Hyperspectral remote sensing, Multidisciplinary, Optical Sensor
- by Anne Thessen
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- Salinity, Pseudo-nitzschia, Gulf of Mexico, Growth rates
- by Andrew Whyte
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- Engineering, Civil Engineering, Engineering Management, Oil and gas

Four drowned shelf-edge delta complexes, two drowned shelf deltas, three drowned barrier islands, large areas of "hardground", and fields of bedforms on the mid and outer continental shelf and uppermost slope north of the head of De Soto Canyon, NE Gulf of Mexico were mapped with high-resolution multibeam echosounder. Deltas formed not during the last eustatic low stand, but during one or more interstadials when eustatic sea levels were only 60 to 80 m below present sea level. The barrier islands and deltas must have been cemented prior to rapid falls of eustatic sea level that occurred during global glaciations. Cementation is necessary to have preserved the barrier islands from erosion and subsequent destruction by the rapid sea-level rise during the last deglaciation. The preservation of the relict bathymetry is so good that features that superficially resemble trough blowouts are found in association with one of the relict barrier islands. Asymmetric bedforms on the midshelf in water depths of 50 to 60 m indicate transport directions to the SW but asymmetric bedforms in water depths of the upper slope between 100 and 120 m on the S and SE flanks of the drowned shelf-edge deltas indicate a different current direction, a separate flow that is a continuation of a SW-flowing current that was previously found on the upper slope off NW Florida.

- by Larry Mayer
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- Geology, Geomorphology, Sea Level, Depth

The chemical and isotopic characterization of formation water from 18 oil production wells, extracted from 5200 to 6100 m b.s.l. at the Jujo-Tecominoacán carbonate reservoir in SE-Mexico, and interpretations of historical production records, were undertaken to determine the origin and hydraulic behavior of deep groundwater systems. The infiltration of surface water during Late Pleistocene to Early Holocene time is suggested by 14 C-concentrations from 2.15 to 31.86 pmC, and by 87 Sr/ 86 Sr-ratios for high-salinity formation water (0.70923-0.70927) that are close to the composition of Holocene to modern seawater. Prior to infiltration, the super-evaporation of seawater reached maximum TDS concentrations of 385 g/ L, with lowest d 18 O values characterizing the most hypersaline samples. Minor deviations of formation water and dolomite host rocks from modern and Jurassic 87 Sr/ 86 Sr-seawater composition, respectively, suggest ongoing water-rock interaction, and partial isotopic equilibration between both phases. The abundance of 14 C in all sampled formation water, 87 Sr/ 86 Sr-ratios for high-salinity water close to Holocene -present seawater composition, a water salinity distribution that is independent of historic water-cut, and a total water extraction volume of 2.037 MMm 3 (1/83-4/07) excludes a connate, oil-leg origin for the produced water of the Jurassic-Cretaceous mudstone-dolomite sequence. Temporal fluctuations of water chemistry in production intervals, the accelerated migration of water fronts from the reservoir flanks, and isotopic mixing trends between sampled wells confirms the existence of free aquifer water below oil horizons. Vertical and lateral hydraulic mobility has probably been accelerated by petroleum extraction.

- by Bruce Eglington
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- Geochemistry, Thermodynamics, Hydraulics, Migration

Biogeography of macro-and microorganisms in the deep sea is, in part, shaped by naturally occurring heterogeneous habitat features of geological and biological origin such as seeps, vents, seamounts, whale and wood-falls. Artificial features including shipwrecks and energy infrastructure shape the biogeographic patterns of macro-organisms; how they influence microorganisms is unclear. Shipwrecks may function as islands of biodiversity for microbiomes, creating a patchwork of habitats with influence radiating out into the seabed. Here we show microbiome richness and diversity increase as a function of proximity to the historic deep-sea shipwreck Anona in the Gulf of Mexico. Diversity and richness extinction plots provide evidence of an island effect on microbiomes. A halo of core taxa on the seabed was observed up to 200 m away from the wreck indicative of the transition zone from shipwreck habitat to the surrounding environment. Transition zones around natural habitat features are often small in area compared to what was observed at Anona indicating shipwrecks may exert a large sphere of influence on seabed microbiomes. Historic shipwrecks are abundant, isolated habitats with global distribution, providing a means to explore contemporary processes shaping biogeography on the seafloor. This work is a case study for how built environments impact microbial biodiversity and provides new information on how arrival of material to the seafloor shapes benthic microbiomes.

- by Leila Hamdan and +1
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- Microbial Ecology, Marine Archaeology, Shipwrecks, Gulf of Mexico

Concentration profiles of dissolved and particulate 210 Pb were measured on horizontal transects of the continental shelf and slope regions of the Gulf of Mexico. Vertical profiles in the slope station in the presence and absence of warmcore ring enable us to evaluate the differences in the scavenging intensity of 210 Pb. A comparison of the rate of production of 210 Pb in the overlying water column to that of its mean annual flux calculated from the sediment inventory allows us to get a better insight in to the lateral transport and deposition of 210 Pb to the slope sediments over a o100 year time scale.

- by Mark Baskaran
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- Earth Sciences, Biological Sciences, Continental shelf, Gulf of Mexico

In this paper, two different types of the mooring system for a FPSO are considered, which is supposed to be installed in Gulf of Mexico. One system consists of 16 mooring lines (four by four) and another one consists of 12 mooring lines (four by three). It is designed that the static system stiffness are almost the same. Then two mooring systems are analyzed from the viewpoint of the extreme load and the fatigue life. A time-domain computational code is used in order to determine the extreme tension, while the spectral method is implemented for estimating the fatigue life.

- by Hang Choi
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- Engineering, Comparative Study, Spectral method, Hydrodynamics

A systematic interpretation of wettability alteration by NMR analysis was carried out on three types of sandstones with varying shalyness. Two fluid systems were investigated. Soltrol 130 was used as the refined oil. A deep water Gulf of Mexico crude oil was used as the crude oil that is known to alter the wettability in restored state core analysis. Fluids

- by George Hirasaki
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- Gulf of Mexico, Crude Oil, Deep water

Fisheries encompass complex interplays between social, economic, and environmental factors, but limitations on historical fisheries data can hamper efforts to identify and contextualize the long-term spatiotemporal patterns that shape them. We integrate 2500 years of stable isotope (δ34S, δ13C, and δ15N) and zooarchaeological evidence from Gulf of Mexico fisheries to assess cultural, demographic, and technological changes affecting sheepshead (Archosargus probatocephalus) populations and fishing practices in Louisiana, USA. Concurrent with human population growth, average sizes of sheepshead caught decreased from the 1720s to 1830s. The size of fish caught after the 1830s increased to pre-1720 levels at the same time that isotopic compositions of fish bone collagen show that fish were being caught from a more diverse range of ecosystems, including distant seagrass beds. Our findings provide the first evidence for large-scale depressions of historical sheepshead populations and the p...

- by Dean Grubbs
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- Gulf of Mexico, Essential Fish Habitat

Detrital sand grains from three beaches (Tecolutla,
Nautla, and Veracruz) along the western Gulf of Mexico were
studied by a scanning electron microscope, to investigate the
depositional environment and paleoclimate. Totally, 24
microtextures are identified; among them, 13 are grouped as
mechanical origin, 5 as mechanical and/or chemical origin, and
6 as chemical origin. These microtextures are nonuniformly
distributed among the three beach areas. Concoidal fractures,
straight and arcuate steps at Tecolutla and Veracruz beaches
indicate that the sand grains were derived from the crystalline
rocks. The abundance of angular outline grains at the Nautla
beach supports for short transportation probably close to the
source area. The domination of rounded sand grains in the
Veracruz beach reveals that the sediments were derived by
the aeolian mechanism. Chattermark trials at the Veracruz
beach sands are indicating a wet tropical climate. Chemical
features like silica globules, silica pellicle, and trapped diatoms
in the Tecolutla and Veracruz beach sands suggest a silica
saturated environment. Similarly, chemical etching and solution
pits are common in the Veracruz beach sands, which are
probably linked to the contaminated sea water. Desiccation
crack at Veracruz beach sands is an indicator of temperature
changes in the beach environment. Broken benthonic foraminifera Elphidium discoidale sp. present in the Veracruz beach indicates a high-energy littoral environment.

Metazoan meiofauna are ubiquitous in marine soft sediments and play a pivotal role in diagenesis of particulate organic matter. However, the relative importance of meiofauna to the function of deep-sea benthic boundary layer communities has not been resolved. Here, meiofauna biomass, respiration, and grazing on aerobic heterotrophic bacteria were estimated and compared to standing stocks and fluxes of other benthic components (e.g., bacteria and macrofauna). Biomass and respiration declined with depth. Highest biomass and respiration occurred in the proximity of the Mississippi River on the upper continental slope of the central Gulf of Mexico. Meiofauna required 7% of their biomass per day to meet their metabolic energy budget, compared to approximately 24% day À1 in shallow water. Respiration accounted for 8-22% of whole sediment community respiration (SCOC), reflecting the importance of meiofauna in diagenesis, deep-sea carbon budgets, and global biogeochemical cycles.

- by Gilbert Rowe and +2
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- Geochemistry, Oceanography, Ecology, Mississippi River
- by Mario Sengco
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- Biological Sciences, Environmental Sciences, Laboratory experiment, Gulf of Mexico

In this document, Kenchington comments on a selected group of documents and papers that represent part of a larger body of work conducted on gag grouper over the last 20 years. The Kenchington document is essentially divided into two broad sections. The first section addresses the status of the gag in the Gulf of Mexico, in which he reviews the stock assessments and work relating to sex ratios, genetic signs of inbreeding, recruitment indices and proposed management recommendations. The second section addresses a summary document prepared for the Gulf Council and the lay public that relates specifically to the effects of shelf-edge fishing on the demographics of the gag and the rationale for proposing a year round closure of aggregation sites. The substance of Kenchington's document largely supports the need to be cautious in the management of gag and that the council will need to take action soon (e.g., p. 22). His main concerns are the change in the sex ratio and the genetics....

- by Christopher Koenig and +1
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- Genetics, Sex ratio, Stock assessment, Gulf of Mexico

The Frampton growth anticline is part of the Atwater Valley-Southern Green Canyon frontal fold belt in the deep-water northeastern Gulf of Mexico. The anticline is located basinward of the allochthonous Sigsbee Salt sheet near the Sigsbee Escarpment. The timing and mechanisms of the formation of the frontal fold have been investigated using palinspatically restored depth sections and by the analysis of the growth stratal architecture preserved on fold limbs. The Frampton anticline is cored by autochthonous Middle Jurassic Louann salt and its western limit is bounded by the Green Knoll diapir. The fold geometry varies along strike, from a symmetric box-fold in the east, to a breached detachment fold in the west. Small-wavelength salt pillows formed during the Late Jurassic-Cretaceous in response to an early contractional deformation. These precursor structures controlled the geometry of Tertiary age folding. The Green Knoll diapir, west of the Frampton anticline, influenced deformation, leading to complex interactions between segments of the fold system and associated thrust faults. A landward-vergent thrust fault accommodated shortening adjacent to the diapir whereas folding was the main mechanism of deformation in the eastern part of Frampton anticline. Analysis of growth strata indicates that the detachment anticline developed according to a progressive limb rotation kinematic model with minor hinge migration. The fold evolution model proposed in this study could be used as an analogue for less well imaged, hydrocarbon-bearing growth folds in the deep-water province of the Gulf of Mexico, particularly those that are partially obscured by overlying allochthonous salt sheets. q

- by Ken McClay
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- Geology, Geophysics, Middle Jurassic, Gulf of Mexico

We used a drop sampler to characterize use of the marsh-edge ecotone by small fishes along two transects running inland from the Gulf of Mexico for ca. 25 km in Louisiana's Barataria-Caminada Bay System. Monthly sampling was stratified among upper, middle, and lower reaches and within reaches to characterize fish responses to salinity, depth, distance from shore, substrate, dissolved oxygen concentration, temperature, turbidity, velocity, and emergent stem density. In 681 quantitative samples, covering 658 m2, collected between October 1987 and October 1989, we collected 57 fish species and 16 864 individuals, primarily larvae and juveniles. The 15 most abundant fishes, comprising 97.7% of all individuals, were concentrated near the marsh edge (i.e., 0 to 1.25 m distance). Some significant differences within species for seasonal variables (e.g., temperature and dissolved oxygen concentration) reflected the ephemeral duration of early life history stages. Other differences reflected ontogenetic microhabitat shifts (e.g., depth and distance from shore). Within ecological groups, characterized as demersal residents, nektonic transients, and demersal transients, spatial and temporal segregation reflected the particular habitat requirements of each species. In a principal component analysis of microhabitat use, the first three components were interpreted as seasonal, depth-anddistance, and salinity axes, respectively. The array of species and size classes in principal component space reflected the complex dimensionality of microhabitat use. The high density of fish larvae and juveniles near the marsh edge confirmed the importance of the marsh-edge ecotone as a nursery for many estuarinedependent fishes.

- by Donald Baltz and +1
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- Zoology, Principal Component Analysis, Ecology, Fish Ecology

This article examines piracy and armed robbery in the Gulf of Mexico, within the framework of ocean governance and maritime transport policy, with a particular focus on maritime security policy. The study focuses on Mexico; however, these findings can also apply to other Latin-American countries facing similar security threats. It also highlights possible solutions as the establishment of an international agreement to govern piracy through State Cooperation, in addition to the effective implementation of the ISPS Code and other appropriate maritime security measures. An important conclusion is that piracy and armed robbery in the Southern part of the Gulf of Mexico has increased significantly during the last years, which has augmented the security risk of the area. This, added to the fact that the Government of Mexico isnot fulfilling their duties and obligations before the international community concerning the obligatory reports to IMO of these type of attacks against vessels is worsening the problem and expanding the risk for vessels, their crews and the marine environment. The researchers documented 11 serious security incidents against ships for the first half of 2020. Recommendations include that ports from the Southern part of the Gulf of Mexico increase the security level to operate at level 2 and that vessels anchored at anchor areas of ports or whenever anchored for oil exploration and production operations in this geographical area, increase the security level to level 2. Finally, the researchers recommend to declare the Southern part of the Gulf of Mexico as a High Risk Area (HRA) and to initiate negotiations for the establishment of a Memorandum of Agreement (MOU), for international cooperation and capacity building with the US Government to reduce security threats and protect the marine environment. These type of attacks against a MODUS or a fixed platform could cause a marine disaster, which pollution would easily reach the US coast because of the marine streams.

- by Dr. Adriana AVILA ZUNIGA NORDFJELD and +1
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- International Cooperation, Piracy, Gulf of Mexico, Armed Robbery

A significant number of offshore oil and gas installations in the United Kingdom’s (UK) North Sea have either exceeded or are approaching the end of their designed economic life. Operators and contractors are confronted with an array of challenges, which hinder the cost effective and safe completion of decommissioning projects. The costing and technological challenges that confront the oil and gas industry are identified using a series of semi-structured interviews. One of the most prominent challenges identified was the inability to reliably estimate the volume and cost of work to be undertaken. This is exacerbated by a supply chain with limited capacity and experience in executing decommissioning projects in this fledgling sector in the oil and gas industry. As a result of the analysis that is undertaken, it is recommended that an industry-wide decommissioning forum be established to facilitate the sharing of experience and knowledge, particularly with regard to cost information so that operators and contractors can ameliorate the planning and management of the decommissioning process.

- by Dominic Ahiaga-Dagbui and +1
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- Engineering, Engineering Management, Oil and gas, Cost Engineering

This paper discusses a joint industry and UK Health and Safety Executive research project on the assessment of safety culture in oshore environments. It particularly describes the development of a safety culture assessment methodology which is based on a systems approach to organisational culture. This approach combines a number of assessment methods, such as: questionnaires, focus groups, behavioural observations and situational audits, to describe and explore the ecacy of health and safety management systems. The evidence produced by these methods are complementary rather than alternatives and provide dierent views of organisational health and safety culture by tapping many aspects of the organisation's structure, function and behaviour. The assessment techniques have been piloted within collaborating organisations, both within the UK and the Gulf of Mexico. The culmination of the work is the``Safety Climate Assessment Toolkit'' which is now published and available for use by managers and safety professionals within the oshore oil extraction industry. # Safety Science 34 www.elsevier.com/locate/ssci 0925-7535/00/$ -see front matter # 2000 Elsevier Science Ltd. All rights reserved. P I I : S 0 9 2 5 -7 5 3 5 ( 0 0 ) 0 0 0 0 9 -6

- by Alistair Cheyne
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- Engineering, Technology, Methodology, Culture

The purpose of this research has been to examine the nature and trends associated with a wide range of industries and activities that support offshore oil and gas exploration, development, and production. The sectors and activities examined include: drilling contractors; underwater contractors (diving); mud, drilling, and lubricants; air transport; water transport; geophysical services; dredging; catering; workover services and environmental consulting and mitigation.
A number of issues and aspects were examined for each of these sectors that includes a basic description of the industry and the types of services provided, typical industry characteristics that includes an examination of typical facilities, the geographical distribution of the firms and their location along the Gulf of Mexico, a description of each sectors’ labor force, and identification of typical or leading firms in those particular sectors.
Each chapter includes an examination of the industry trends and outlook for that respective support sector/activity including a discussion of the impacts that hurricane activity of 2005 had on each of the various support sectors and activities.

- by Carly Voight
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- Marine Biology, Spatial Analysis, Central America and Mexico, Tropical Ecology

Upper Jurassic Haynesville and Bossier shale-gas plays of the northwestern Gulf of Mexico (GOM) Basin produce from organic-rich, marine transgressive to highstand mudrocks within mixed carbonate-clastic depositional systems. Modern wireline-log suites from w200 deep wells were used for detailed correlations, and 10 þ cores throughout the upper Kimmeridgian to lower Tithonian basin were incorporated into detailed facies, stratigraphic, and lithologic analyses. The Haynesville Shale lies within a 2nd-order transgressive systems tract (TST) that encompasses back-stepping ramp carbonates (proximal) and marine shales (distal) below a maximum flooding surface (MFS). This shale onlaps retrogradational carbonates and basement highs and is capped by the 2nd-order MFS. Bossier shales and local sandstones prograde basinward above the Haynesville shale and downlap the 2nd-order MFS. They grade upward and updip into the thick, highstand systems tract (HST), fluvio-deltaic sandstones of the Cotton Valley Group. Distally, organic-rich facies developed in restricted Bossier environments, creating another productive gas-shale opportunity. Several preexisting basement highs in the south and carbonate platforms in the northwest and west restrict and partition the basin, thus influencing deposition of highly organic versus nonorganic and siliciclastic-dominated versus carbonate-dominated lithologies. Haynesville and Bossier shales each compose three upward-coarsening cycles that probably represent 3rdorder sequences within the larger 2nd-order TST and early HST, respectively. Most of the three Bossier 3rd-order cycles are dominated by varying amounts of siliciclastics. Deposition of the Haynesville mudrocks occurred below storm-wave base under mostly dysoxic conditionsm allowing settlement of benthic bivalve communities and bioturbating organisms and oscillating periodically to more anoxic conditions on the seafloor. However, most of the sparse faunae found in these mudrocks are of planktonic origin. Bossier mudrocks exhibited more oxygenated and clastic-rich lithologies related to progradation of the clastic shoreline and sea-level highstand. Knowledge of lithologic, stratigraphic, geochemical, and faunal variations across mudrock basins needs to be detailed so that shale-gas basins might be successfully explored.

- by Ursula Hammes
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- Geology, Geophysics, Sea Level, Sequence Stratigraphy

Hurricane Katrina created the one of the worst natural disaster in the history of the United States, resulting in over 1600 fatalities and $30B in direct economic losses in southern Louisiana. The Louisiana and Mississippi coastlines experienced the highest surge level recorded in North America and Katrinagenerated waves in the Gulf of Mexico that equaled the highest previously measured by NOAA buoys. What happened in New Orleans epitomizes the risk of living below sea level in a coastal city, depending on structures that were the result of considerable compromise and piecemeal funding and construction. The Interagency Performance Evaluation Task Force was established to examine the performance of the New Orleans and southeast Louisiana hurricane protection system and provide real-time input to the repairs and rebuilding of the system. In addition to this atypical just-in-time forensic analysis, the task force examined the risk of living in New Orleans prior to and following the repairs to the hurricane protection system. Much of the forensic analysis depended on modeling and simulation of hurricane surge and waves. With virtually all measurement instruments swept away by Katrina, only models and high-water marks were available to recreate the conditions that the structures experienced during the storm. Because of the complexities of the region and the processes involved, simulation of hurricane surge and waves required many fresh ideas and new approaches and these topics, along with new concepts for future planning and design, are the focus of this special issue. Yet, the need to influence the repair and rebuilding of the damaged structures prior to the next hurricane season (roughly 9 months) dictated using existing computational tools that were ready to go. The same modeling and simulation approach was put to work to define the surge and wave hazard New Orleans faces for the future. To put this important body of work in context, this paper provides a broad overview of the entire scope of work of the task force and summarizes its principal findings.

- by Lewis Link
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- Civil Engineering, Ocean Engineering, Modeling and Simulation, Risk assessment