33 CFR 334.720 - Gulf of Mexico, south from Choctawhatchee Bay; guided missiles test operations area, Headquarters...

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Gulf of Mexico, south from..., DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.720 Gulf of Mexico, south from Choctawhatchee Bay; guided missiles test operations area, Headquarters Air Proving...

Northern Gulf Littoral Initiative (NGLI), Geology and Physical Properties of Marine Sediments in the N.E. Gulf of Mexico: Data Report

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Northern Gulf Littoral Initiative (NGLI), Geology and Physical Properties of Marine Sediments in the N.E. gulf of Mexico: Data Report, was produced by the U.S....

Northern Gulf of Mexico Marine Mammal Unusual Mortality Event Database

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Tissues and samples collected from marine mammals during investigation of the Northern Gulf of Mexico Marine Mammal Unusual Mortality Event are tracked within this...

Coastal change and hypoxia in the northern Gulf of Mexico: Part I

Directory of Open Access Journals (Sweden)

2007-01-01

Full Text Available The Committee on Environment and Natural Resources (CENR has identified the input of nutrient-rich water from the Mississippi/Atchafalaya River Basin (MARB as the prime cause of hypoxia in the northern Gulf of Mexico and the prime means for its control. A Watershed Nutrient Task Force was formed to solve the hypoxia problem by managing the MARB catchment. However, the hypoxic zone is also experiencing massive physical, hydrological, chemical and biological changes associated with an immense river-switching and delta-building event that occurs here about once a millennium. Coastal change induced hypoxia in the northern Gulf of Mexico prior to European settlement. It is recommended that for further understanding and control of Gulf hypoxia the Watershed Nutrient Task Force adopt a truly holistic environmental approach which includes the full effects of this highly dynamic coastal area.

Topobathymetric Model of the Northern Gulf of Mexico, 1888 to 2013

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Accurate, high-resolution elevation information is vital to understanding the highly dynamic Northern Gulf Coast, with Louisiana being the location of North...

Waves off Gopalpur, northern Bay of Bengal during cyclone Phailin.

Digital Repository Service at National Institute of Oceanography (India)

Amrutha, M.M.; SanilKumar, V.; Anoop, T.R.; Nair, T.M.B.; Nherakkol, A.; Jeyakumar, C.

, 1073–1083, 2014 www.ann-geophys.net/32/1073/2014/ doi:10.5194/angeo-32-1073-2014 © Author(s) 2014. CC Attribution 3.0 License. Waves off Gopalpur, northern Bay of Bengal during Cyclone Phailin M. M. Amrutha1, V. Sanil Kumar1, T. R. Anoop1, T. M..., 1073–1083, 2014 www.ann-geophys.net/32/1073/2014/ M. M. Amrutha et al.: Waves off Gopalpur, northern Bay of Bengal during Cyclone Phailin 1075 Figure 1. Track of the Cyclone Phailin from 8 October 2013 03:00 UTC to 13 October 2013 06:00 UTC. S(f )= αg 2...

Aerial radiometric and magnetic survey: Beeville/Bay City National Topographic Map, Texas Gulf Coast

International Nuclear Information System (INIS)

1979-01-01

As part of the National Uranium Resource Evaluation program Geodata International, Inc. of Dallas, Texas, conducted an airborne gamma ray and total magnetic field survey of Beeville/Bay City Quadrangle of the Texas Gulf Coast area. Volume 1 gives the description of the program and results, and volume 2 gives the flight line profile data and statistical analysis results. The Beeville/Bay City Map Sheet shows Tertiary and Quaternary-aged strata which are part of the coastal plain of the Gulf Coast Geosyncline. The Cenozoic sediments overlie Mesozoic, Paleozoic, and Precambrian rocks, and have a relatively gentle homoclinal dip toward the gulf. The Quaternary and Tertiary sediments of the map sheet overlie the western flank of the Houston-East Texas Embayment, the northeastern side of the Rio Grande Embayment, and the San Marcos Arch. Recent and Pleistocene sediments crop-out in the south and east, and are more extensive in the vicinity of the structural embayments. The Pliocene-aged Goliad Formation crops-out extensively to the northwest. Miocene and Eocene strata occur in the northwestern corner of the map sheet. The uranium deposits occur in the Tertiary strata, but are most intensely mined in the Eocene strata immediately to the west of the map sheet area

Deep-water northern Gulf of Mexico hydrocarbon plays

International Nuclear Information System (INIS)

Peterson, R.H.; Cooke, D.W.

1995-01-01

The geologic setting in the deep-water (depths greater than 1,500 feet) Gulf of Mexico is very favorable for the existence of large, commercial hydrocarbon accumulations. These areas have active salt tectonics that create abundant traps, underlying mature Mesozoic source rocks that can be observed expelling oil and gas to the ocean surface, and good quality reservoirs provided by turbidite sand deposits. Despite the limited amount of drilling in the deep-water Gulf of Mexico, 11 deep-water accumulations have been discovered which, when developed, will rank in the top 100 largest fields in the Gulf of Mexico. Proved field discoveries (those with announced development plans) have added over 1 billion barrels of oil equivalent to Gulf of Mexico reserves, and unproved field discoveries may add to additional billion barrels of oil equivalent. The Minerals Management Service, United States Department of the Interior, has completed a gulf-wide review of over 1,086 oil and gas fields and placed every pay sand in each field into a hydrocarbon play (plays are defined by chronostratigraphy, lithostratigraph, structure, and production). Seven productive hydrocarbon plays were identified in the deep-water northern Gulf of Mexico. Regional maps illustrate the productive limits of each play. In addition, field data, dry holes, and wells with sub-economic pay were added to define the facies and structural limits for each play. Areas for exploration potential are identified for each hydrocarbon play. A type field for each play is chosen to demonstrate the play's characteristics

Rayleigh and Love Wave Phase Velocities in the Northern Gulf Coast of the United States

Science.gov (United States)

Li, A.; Yao, Y.

2017-12-01

The last major tectonic event in the northern Gulf Coast of the United States is Mesozoic continental rifting that formed the Gulf of Mexico. This area also experienced igneous activity and local uplifts during Cretaceous. To investigate lithosphere evolution associated with the rifting and igneous activity, we construct Rayleigh and Love wave phase velocity models at the periods of 6 s to 125 s in the northern Gulf Coast from Louisiana to Alabama including the eastern Ouachita and southern Appalachian orogeny. The phase velocities are derived from ambient noise and earthquake data recorded at the 120 USArray Transportable Array stations. At periods below 20 s, phase velocity maps are characterized by significant low velocities in the Interior Salt Basin and Gulf Coast Basin, reflecting the effects of thick sediments. The northern Louisiana and southern Arkansas are imaged as a low velocity anomaly in Rayleigh wave models but a high velocity anomaly of Love wave at the periods of 14 s to 30 s, indicating strong lower crust extension to the Ouachita front. High velocity is present in the Mississippi Valley Graben from period 20 s to 35 s, probably reflecting a thin crust or high-velocity lower crust. At longer periods, low velocities are along the Mississippi River to the Gulf Coast Basin, and high velocity anomaly mainly locates in the Black Warrior Basin between the Ouachita Belt and Appalachian Orogeny. The magnitude of anomalies in Love wave images is much smaller than that in Rayleigh wave models, which is probably due to radial anisotropy in the upper mantle. A 3-D anisotropic shear velocity model will be developed from the phase velocities and will provide more details for the crust and upper mantle structure beneath the northern Gulf of Mexico continental margin.

Evaluation of ecotourism potential in the northern coastline of the Persian Gulf

Science.gov (United States)

Nouri, Jafar; Danehkar, Afshin; Sharifipour, Rozita

2008-08-01

This research has identified areas located in the northern coastline of the Persian Gulf in the south of Iran, as strategic and ecological sites, based on tourism potential assessing criteria. To this end coastal limits were identified by satellite imagery in terms of shorelines and the maximum extent of water approach into the land and taking into consideration the characteristics of the nearby coastal villages. The studied region was then compared to similar international criteria and experiences. The original criteria were then divided into three main and four sub criteria. The Kangan region was found to have a potential for tourism industry according to the mentioned criteria. Naiband Gulf with a score of 20 was ranked first followed by Asalouyeh with a score of 18 and finally Taheri and Kangan Ports with scores of 16 and 15, respectively. With a high tourism industry potential in the studied region the necessity of ecotourism quality enhancement and environmental management planning for the northern shoreline of the Persian Gulf becomes of vital importance.

A survey of cardinalfish (Apogonidae) of Antsiranana Bay, northern ...

African Journals Online (AJOL)

The cardinalfish of Antsiranana Bay, northern Madagascar, were surveyed over an 11 month period by underwater census employing a simple search pattern using self-contained underwater breathing apparatus. Over this period 15 species were observed including one species not previously recorded in Madagascar, ...

Temperature of the Gulf Stream

Science.gov (United States)

2002-01-01

The Gulf Stream is one of the strong ocean currents that carries warm water from the sunny tropics to higher latitudes. The current stretches from the Gulf of Mexico up the East Coast of the United States, departs from North America south of the Chesapeake Bay, and heads across the Atlantic to the British Isles. The water within the Gulf Stream moves at the stately pace of 4 miles per hour. Even though the current cools as the water travels thousands of miles, it remains strong enough to moderate the Northern European climate. The image above was derived from the infrared measurements of the Moderate-resolution Imaging Spectroradiometer (MODIS) on a nearly cloud-free day over the east coast of the United States. The coldest waters are shown as purple, with blue, green, yellow, and red representing progressively warmer water. Temperatures range from about 7 to 22 degrees Celsius. The core of the Gulf Stream is very apparent as the warmest water, dark red. It departs from the coast at Cape Hatteras, North Carolina. The cool, shelf water from the north entrains the warmer outflows from the Chesapeake and Delaware Bays. The north wall of the Gulf Stream reveals very complex structure associated with frontal instabilities that lead to exchanges between the Gulf Stream and inshore waters. Several clockwise-rotating warm core eddies are evident north of the core of the Gulf Stream, which enhance the exchange of heat and water between the coastal and deep ocean. Cold core eddies, which rotate counter clockwise, are seen south of the Gulf Stream. The one closest to Cape Hatteras is entraining very warm Gulf Stream waters on its northwest circumference. Near the coast, shallower waters have warmed due to solar heating, while the deeper waters offshore are markedly cooler (dark blue). MODIS made this observation on May 8, 2000, at 11:45 a.m. EDT. For more information, see the MODIS-Ocean web page. The sea surface temperature image was created at the University of Miami using

78 FR 16628 - Gulf of the Farallones and Monterey Bay National Marine Sanctuaries Regulations on Introduced...

Science.gov (United States)

2013-03-18

... Register on October 1, 2009 (74 FR 50740) concerning regulations on the introduction of introduced species... Sanctuaries (ONMS) conducted a joint review of the management plans for Gulf of the Farallones, Monterey Bay and Cordell Bank national marine sanctuaries (hereafter referred to as the ``Joint Management Plan...

Simulating environmental effects on brown shrimp production in the northern Gulf of Mexico

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Brown shrimp (Farfantepenaeus aztecus) are a commercially important fishery species of the northern Gulf of Mexico. Young shrimp settle in estuarine salt marsh...

Using Remotely Sensed Data and Hydrologic Models to Evaluate the Effects of Climate Change on Shallow Aquatic Ecosystems in the Mobile Bay, AL Estuary

Science.gov (United States)

Estes, M. G.; Al-Hamdan, M. Z.; Thom, R.; Judd, C.; Ellis, J.; Woodruff, D.; Quattrochi, D.; Rose, K.; Swann, R.

2012-12-01

Coastal systems in the northern Gulf of Mexico, including the Mobile Bay, AL estuary, are subject to increasing pressure from a variety of activities including climate change. Climate changes have a direct effect on the discharge of rivers that drain into Mobile Bay and adjacent coastal water bodies. The outflows change water quality (temperature, salinity, and sediment concentrations) in the shallow aquatic areas and affect ecosystem functioning. Mobile Bay is a vital ecosystem that provides habitat for many species of fauna and flora. Historically, submerged aquatic vegetation (SAV) and seagrasses were found in this area of the northern Gulf of Mexico; however the extent of vegetation has significantly decreased over the last 60 years. The objectives of this research are to determine: how climate changes affect runoff and water quality in the estuary and how these changes will affect habitat suitability for SAV and seagrasses. Our approach is to use watershed and hydrodynamic modeling to evaluate the impact of climate change on shallow water aquatic ecosystems in Mobile Bay and adjacent coastal areas. Remotely sensed Landsat data were used for current land cover land use (LCLU) model input and the data provided by Intergovernmental Panel on Climate Change (IPCC) of the future changes in temperature, precipitation, and sea level rise were used to create the climate scenarios for the 2025 and 2050 model simulations. Project results are being shared with Gulf coast stakeholders through the Gulf of Mexico Data Atlas to benefit coastal policy and climate change adaptation strategies.

Using Remotely Sensed Data and Hydrologic Models to Evaluate the Effects of Climate Change on Shallow Aquatic Ecosystems in the Mobile Bay, AL Estuary

Science.gov (United States)

Estes, M. G.; Al-Hamdan, M. Z.; Thom, R.; Judd, C.; Woodruff, D.; Ellis, J. T.; Quattrochi, D.; Swann, R.

2012-01-01

Coastal systems in the northern Gulf of Mexico, including the Mobile Bay, AL estuary, are subject to increasing pressure from a variety of activities including climate change. Climate changes have a direct effect on the discharge of rivers that drain into Mobile Bay and adjacent coastal water bodies. The outflows change water quality (temperature, salinity, and sediment concentrations) in the shallow aquatic areas and affect ecosystem functioning. Mobile Bay is a vital ecosystem that provides habitat for many species of fauna and flora. Historically, submerged aquatic vegetation (SAV) and seagrasses were found in this area of the northern Gulf of Mexico; however the extent of vegetation has significantly decreased over the last 60 years. The objectives of this research are to determine: how climate changes affect runoff and water quality in the estuary and how these changes will affect habitat suitability for SAV and seagrasses. Our approach is to use watershed and hydrodynamic modeling to evaluate the impact of climate change on shallow water aquatic ecosystems in Mobile Bay and adjacent coastal areas. Remotely sensed Landsat data were used for current land cover land use (LCLU) model input and the data provided by Intergovernmental Panel on Climate Change (IPCC) of the future changes in temperature, precipitation, and sea level rise were used to create the climate scenarios for the 2025 and 2050 model simulations. Project results are being shared with Gulf coast stakeholders through the Gulf of Mexico Data Atlas to benefit coastal policy and climate change adaptation strategies.

River inputs and organic matter fluxes in the northern Bay of Bengal: Fatty acids

Digital Repository Service at National Institute of Oceanography (India)

Reemtsma, T.; Ittekkot, V.; Bartsch, M.; Nair, R.R

) 55-71 55 Elsevier Science Publishers B.V., Amsterdam \\[RA\\] River inputs and organic matter fluxes in the northern Bay of Bengal: fatty acids T. Reemtsma a, V. Ittekkot a, M. Bartsch a and R.R. Nair b alnstitut fiir Biogeochemie und Meereschemie..., R.R., 1993. River inputs and organic matter fluxes in the northern Bay of Bengal: fatty acids. Chem. Geol., 103: 55-71. Total particulate matter flux and organic carbon and fatty acid fluxes associated with settling particles collected during...

Ocean currents structuring the mesozooplankton in the Gulf of Mannar and the Palk Bay, southeast coast of India

Digital Repository Service at National Institute of Oceanography (India)

Jagadeesan, L.; Jyothibabu, R.; Anjusha, A.; Mohan, A.P.; Madhu, N.V.; Muraleedharan, K.R.; Sudheesh, K.

for the observed variance in copepod distribution. In general, the copepod community in the Gulf of Mannar was composed both of coastal and offshore species whereas, coastal species largely inhabited the Palk Bay. This kind of a study depicting zooplankton...

Baseline concentrations of strontium and 90Sr in seawater from the northern Gulf

International Nuclear Information System (INIS)

Uddin, S.; Al Ghadban, A.N.; Behbahani, M.

2013-01-01

Highlights: • This is the first baseline for strontium and 90 Sr from northern Gulf. • The total strontium concentration is much higher than reported for other oceans. • The Sr/salinity ratio correlates well with global averages. • High Sr might be due to increased salinity/CaCo 3 dissolution in acidifying Gulf waters. -- Abstract: Baseline concentration of strontium and Sr-90 in Gulf is presented. The strontium concentration is much higher than reported for other oceanic waters, while the Sr-90 concentration is low at 0.7–1.0 mBq l −1 , that represents the background level following nuclear tests and can be used as an effective tracer in case of any radioactive release in the region. The strontium concentration is primarily related to the increasing salinity off the Gulf coast

33 CFR 334.670 - Gulf of Mexico south and west of Apalachicola, San Blas, and St. Joseph bays; air-to-air firing...

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Gulf of Mexico south and west of Apalachicola, San Blas, and St. Joseph bays; air-to-air firing practice range, Tyndall Air Force Base, Fla. 334..., DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.670 Gulf of Mexico south and west of...

Genetic population structure of the lionfish Pterois miles (Scorpaenidae, Pteroinae) in the Gulf of Aqaba and northern Red Sea.

Science.gov (United States)

Kochzius, Marc; Blohm, Dietmar

2005-03-14

The aim of this study is to reveal gene flow between populations of the coral reef dwelling lionfish Pterois miles in the Gulf of Aqaba and northern Red Sea. Due to the fjord-like hydrography and topology of the Gulf of Aqaba, isolation of populations might be possible. Analysis of 5' mitochondrial control region sequences from 94 P. miles specimens detected 32 polymorphic sites, yielding 38 haplotypes. Sequence divergence among different haplotypes ranged from 0.6% to 9.9% and genetic diversity was high (h=0.85, pi=1.9%). AMOVA indicates panmixia between the Gulf of Aqaba and northern Red Sea, but analysis of migration pattern shows an almost unidirectional migration originating from the Red Sea.

Demographic clusters identified within the northern Gulf of Mexico common bottlenose dolphin (Tursiops truncates unusual mortality event: January 2010-June 2013.

Directory of Open Access Journals (Sweden)

Stephanie Venn-Watson

Full Text Available A multi-year unusual mortality event (UME involving primarily common bottlenose dolphins (Tursiops truncates was declared in the northern Gulf of Mexico (GoM with an initial start date of February 2010 and remains ongoing as of August 2014. To examine potential changing characteristics of the UME over time, we compared the number and demographics of dolphin strandings from January 2010 through June 2013 across the entire GoM as well as against baseline (1990-2009 GoM stranding patterns. Years 2010 and 2011 had the highest annual number of stranded dolphins since Louisiana's record began, and 2011 was one of the years with the highest strandings for both Mississippi and Alabama. Statewide, annual numbers of stranded dolphins were not elevated for GoM coasts of Florida or Texas during the UME period. Demographic, spatial, and temporal clusters identified within this UME included increased strandings in northern coastal Louisiana and Mississippi (March-May 2010; Barataria Bay, Louisiana (August 2010-December 2011; Mississippi and Alabama (2011, including a high prevalence and number of stranded perinates; and multiple GoM states during early 2013. While the causes of the GoM UME have not been determined, the location and magnitude of dolphin strandings during and the year following the 2010 Deepwater Horizon oil spill, including the Barataria Bay cluster from August 2010 to December 2011, overlap in time and space with locations that received heavy and prolonged oiling. There are, however, multiple known causes of previous GoM dolphin UMEs, including brevetoxicosis and dolphin morbillivirus. Additionally, increased dolphin strandings occurred in northern Louisiana and Mississippi before the Deepwater Horizon oil spill. Identification of spatial, temporal, and demographic clusters within the UME suggest that this mortality event may involve different contributing factors varying by location, time, and bottlenose dolphin populations that will be

Response of the Mississippi Bight and Sound to the Passage of Tropical Storm Cindy Through the Northern Gulf of Mexico

Science.gov (United States)

Hode, L. E.; Howden, S. D.; Diercks, A. R.; Cambazoglu, M. K.; Jones, E. B.; Martin, K. M.

2017-12-01

Damage inflicted by tropical storms and hurricanes on coastal communities and industries has become a growing concern in recent decades. Consequently, utilizing products from existing ocean observing platforms, ocean modeling forecasts and satellite data helps to identify the effects of individual storms on the northern Gulf of Mexico. Using data from the jointly-operated United States Geological Survey and Mississippi Department of Marine Resources (USGS-MDMR) hydrological stations, National Oceanic and Atmospheric Administration (NOAA) tide gages, and the Central Gulf of Mexico Ocean Observing System (CenGOOS) high frequency radar (HFR) network, we tracked temperature, salinity, water level and surface current changes in the Mississippi Sound and Bight during June 2017. We performed time series analyses and compared conditions during the buildup and passage of tropical storm Cindy to climatological values as well as to satellite observations and results from a regional application of the Navy Coastal Ocean Model (NCOM). Elevated salinities proceeded Cindy's landfall on June 22, 2017, while anomalously fresh water marked all Mississippi Sound stations afterwards. Onshore surface currents dominated the Mississippi Bight, and current speeds exceeded more than four times the climatological average in the southeastern Bight. Indeed, regions of enhanced current speeds were observed throughout the month of June 2017. Tidal ranges in the Mississippi Sound were on average half a meter higher than predicted, and Shell Beach (Louisiana) and the Bay Waveland Yacht Club (Mississippi) saw extended periods where tides exceeded one meter above predicted values. These results help to quantify the tidal inundation caused by Cindy but also illustrate the massive riverine discharge driven by the storm's precipitation. Model results provide information on areas of the study region not covered by measurements; additionally, comparing observations to model products helps estimate model

Spatial variation of phytoplankton community structure in Daya Bay, China.

Science.gov (United States)

Jiang, Zhao-Yu; Wang, You-Shao; Cheng, Hao; Zhang, Jian-Dong; Fei, Jiao

2015-10-01

Daya Bay is one of the largest and most important gulfs in the southern coast of China, in the northern part of the South China Sea. The phylogenetic diversity and spatial distribution of phytoplankton from the Daya Bay surface water and the relationship with the in situ water environment were investigated by the clone library of the large subunit of ribulose-1, 5-bisphosphate carboxylase (rbcL) gene. The dominant species of phytoplankton were diatoms and eustigmatophytes, which accounted for 81.9 % of all the clones of the rbcL genes. Prymnesiophytes were widely spread and wide varieties lived in Daya Bay, whereas the quantity was limited. The community structure of phytoplankton was shaped by pH and salinity and the concentration of silicate, phosphorus and nitrite. The phytoplankton biomass was significantly positively affected by phosphorus and nitrite but negatively by salinity and pH. Therefore, the phytoplankton distribution and biomass from Daya Bay were doubly affected by anthropic activities and natural factors.

Single-beam bathymetry data collected in 2015 from Grand Bay, Alabama-Mississippi

Science.gov (United States)

DeWitt, Nancy T.; Stalk, Chelsea A.; Smith, Christopher G.; Locker, Stanley D.; Fredericks, Jake J.; McCloskey, Terrence A.; Wheaton, Cathryn J.

2017-12-01

As part of the Sea-level and Storm Impacts on Estuarine Environments and Shorelines (SSIEES) project, scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center conducted a single-beam bathymetry survey within the estuarine, open-bay, and tidal creek environments of Grand Bay, Alabama-Mississippi, from May to June 2015. The goal of the SSIEES project is to assess the physical controls of sediment and material exchange between wetlands and estuarine environments along the northern Gulf of Mexico, specifically Grand Bay, Alabama-Mississippi; Vermilion Bay, Louisiana; and, along the east coast, within Chincoteague Bay, Virginia-Maryland. The data described in this report provide baseline bathymetric information for future research investigating wetland-marsh evolution, sediment transport, erosion, recent and long-term geomorphic change, and can also support the modeling of changes in response to restoration and storm impacts. The survey area encompasses more than 40 square kilometers of Grand Bay’s waters.

Geothermal resources of the northern gulf of Mexico basin

Science.gov (United States)

Jones, P.H.

1970-01-01

Published geothermal gradient maps for the northern Gulf of Mexico basin indicate little or no potential for the development of geothermal resources. Results of deep drilling, from 4000 to 7000 meters or more, during the past decade however, define very sharp increases in geothermal gradient which are associated with the occurrence of abnormally high interstitial fluid pressure (geopressure). Bounded by regional growth faults along the landward margin of the Gulf Basin, the geopressured zone extends some 1300 km from the Rio Grande (at the boundary between the United States and Mexico) to the mouth of the Mississippi river. Gulfward, it extends to an unknown distance across the Continental Shelf. Within geopressured deposits, geothermal gradients range upwards to 100 ??C/km, being greatest within and immediately below the depth interval in which the maximum pressure gradient change occurs. The 120 ??C isogeotherm ranges from about 2500 to 5000 m below sea level, and conforms in a general way with depth of occurrence of the top of the geopressured zone. Measured geostatic ratios range upward to 0.97; the maximum observed temperature is 273 ??C, at a depth of 5859 m. Dehydration of montmorillonite, which comprises 60 to 80 percent of clay deposited in the northern Gulf Basin during the Neogene, occurs at depths where temperature exceeds about 80 ??C, and is generally complete at depths where temperature exceeds 120 ??C. This process converts intracrystalline and bound water to free pore water, the volume produced being roughly equivalent to half the volume of montmorillonite so altered. Produced water is fresh, and has low viscosity and density. Sand-bed aquifers of deltaic, longshore, or marine origin form excellent avenues for drainage of geopressured deposits by wells, each of which may yield 10,000 m3 or more of superheated water per day from reservoirs having pressures up to 1000 bars at depths greater than 5000 m. ?? 1971.

Trophic efficiency of plankton food webs: Observations from the Gulf of Mannar and the Palk Bay, Southeast Coast of India

Digital Repository Service at National Institute of Oceanography (India)

Anjusha, A.; Jyothibabu, R; Jagadeesan, L.; Mohan, A.P.; Sudheesh, K.; Krishna, K.; Ullas, N.; Deepak, M.P.

This paper introduces the structure and trophic efficiency of plankton food webs in the Gulf of Mannar (GoM) and the Palk Bay (PB) - two least studied marine environments located between India and Sri Lanka. The study is based on the results...

Macrobenthic community structure in the northern Saudi waters of the Gulf, 14years after the 1991 oil spill

KAUST Repository

Joydas, Thadickal Viswanathan

2012-02-01

The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gulf and recent studies have indicated that even 15. years after the incident, macrobenthos had not completely recovered in the sheltered bays in the affected region such as, Manifa Bay. This study investigates the community conditions of macrobenthos in the open waters in one of the impacted areas, Al-Khafji waters, about 14. years after the spill. Diversity measures and community structure analyses indicate a healthy status of polychaete communities. The BOPA index reveals that oil sensitive amphipods were recolonized in the study area. This confirms that the benthic communities of the oil spill impacted area had taken only <14 years to recover in the open waters of the impacted areas. The study also reveals the existence of three distinct polychaete communities along the depth and sediment gradients. © 2011 Elsevier Ltd.

Macrobenthic community structure in the northern Saudi waters of the Gulf, 14years after the 1991 oil spill

KAUST Repository

Joydas, Thadickal Viswanathan; Qurban, Mohammad Ali; Al-Suwailem, Abdulaziz M.; Krishnakumar, P. K.; Nazeer, Zahid B.; Cali, N. A.

2012-01-01

The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gulf and recent studies have indicated that even 15. years after the incident, macrobenthos had not completely recovered in the sheltered bays in the affected region such as, Manifa Bay. This study investigates the community conditions of macrobenthos in the open waters in one of the impacted areas, Al-Khafji waters, about 14. years after the spill. Diversity measures and community structure analyses indicate a healthy status of polychaete communities. The BOPA index reveals that oil sensitive amphipods were recolonized in the study area. This confirms that the benthic communities of the oil spill impacted area had taken only <14 years to recover in the open waters of the impacted areas. The study also reveals the existence of three distinct polychaete communities along the depth and sediment gradients. © 2011 Elsevier Ltd.

Horizontal movements of Atlantic blue marlin (Makaira nigricans) in the Gulf of Mexico

Science.gov (United States)

Kraus, R.T.; Wells, R.J.D.; Rooker, J.R.

2011-01-01

We examined movements of Atlantic blue marlin (Makaira nigricans) from the Gulf of Mexico based upon 42 pop-up archival transmitting (PAT) tags. Long deployments (including one 334-day track) revealed diverse movement patterns within the Gulf of Mexico. North-south seasonal changes in blue marlin distribution showed strong correspondence with established seasonal patterns of sea surface temperature and primary production. During the summer spawning season, blue marlin utilized outer shelf and shelf edge waters in the northern Gulf of Mexico, and longer duration tracks indicated overwintering habitats in the Bay of Campeche. Egress occurred throughout the year and was difficult to determine because some tracks ended in the Straits of Florida (n = 3) while other tracks recorded movement through it or the Yucatan Channel (n = 4). Our results indicate that Atlantic blue marlin have a more restricted geographic range of habitats than previously recognized and that the Gulf of Mexico provides spatially dynamic suitable habitat that is utilized year-round through seasonal movements. ?? 2011 Springer-Verlag.

Bioaccumulation of 210Po in common gastropod and bivalve species from the northern Gulf.

Science.gov (United States)

Uddin, S; Bebhehani, M

2014-06-01

This study sets the baseline for the concentration of the natural-series radionuclide polonium-210 in two species of gastropods and four species of bivalves that are common to the Northern Arabian/Persian Gulf. (210)Po is primarily absorbed from water and via ingestion of detrital material by gastropoda and bivalves. This concentrated (210)Po can then be passed along to the next trophic level of the marine food web. The lowest (210)Po concentration was measured in the gastropod Stomatella auricular (10.36-12.39Bq kg(-1)dry) and the highest in the bivalve Marica marmorata (193.51-215.60Bq kg(-1)dry). The measured concentration factor for these molluscs in the northern Gulf varied between 4.8 and 115×10(3), values very similar to the IAEA recommended value for bivalves and gastropods of 2×10(4). Copyright © 2014 Elsevier Inc. All rights reserved.

Macondo-1 well oil-derived polycyclic aromatic hydrocarbons in mesozooplankton from the northern Gulf of Mexico

Science.gov (United States)

Mitra, Siddhartha; Kimmel, David G.; Snyder, Jessica; Scalise, Kimberly; McGlaughon, Benjamin D.; Roman, Michael R.; Jahn, Ginger L.; Pierson, James J.; Brandt, Stephen B.; Montoya, Joseph P.; Rosenbauer, Robert J.; Lorenson, T.D.; Wong, Florence L.; Campbell, Pamela L.

2012-01-01

Mesozooplankton (>200 μm) collected in August and September of 2010 from the northern Gulf of Mexico show evidence of exposure to polycyclic aromatic hydrocarbons (PAHs). Multivariate statistical analysis revealed that distributions of PAHs extracted from mesozooplankton were related to the oil released from the ruptured British Petroleum Macondo-1 (M-1) well associated with the R/VDeepwater Horizon blowout. Mesozooplankton contained 0.03–97.9 ng g−1 of total PAHs and ratios of fluoranthene to fluoranthene + pyrene less than 0.44, indicating a liquid fossil fuel source. The distribution of PAHs isolated from mesozooplankton extracted in this study shows that the 2010 Deepwater Horizon spill may have contributed to contamination in the northern Gulf of Mexico ecosystem.

33 CFR 334.660 - Gulf of Mexico and Apalachicola Bay south of Apalachicola, Fla., Drone Recovery Area, Tyndall Air...

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Gulf of Mexico and Apalachicola Bay south of Apalachicola, Fla., Drone Recovery Area, Tyndall Air Force Base, Fla. 334.660 Section 334... Apalachicola, Fla., Drone Recovery Area, Tyndall Air Force Base, Fla. (a) The restricted area. A rectangular...

Characterization of phytoplankton pigments and functional community structure in the Gulf of Mannar and the Palk Bay using HPLC–CHEMTAX analysis.

Digital Repository Service at National Institute of Oceanography (India)

Madhu, N.V.; Ullas, N.; Ashwini, R.; Meenu, P.; Rehitha, T.V.; Lallu, K.R.

Phytoplankton marker pigments and their functional groups were identified for the first time in the Gulf of Mannar (GoM) and the Palk Bay (PB), located in the southeast coast of India using HPLC–CHEMTAX analytical techniques. The GoM generally...

Marine Maladies? Worms, Germs, and Other Symbionts from the Northern Gulf of Mexico.

Science.gov (United States)

Overstreet, Robin M.

Parasites and related symbionts of marine and estuarine hosts of the northern Gulf of Mexico are described in this guidebook. It is meant primarily to serve as a teaching aid for the novice student, but it also contains more technical aspects for the experienced parasitologist. Forms and examples of symbiosis are explained in an introductory…

AFSC/REFM: Nearshore fish survey in northern Bristol Bay, Alaska, July-August 2009

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The project consisted of a nearshore fish, invertebrate, and habitat survey in northern Bristol Bay, Alaska. A 32-ft. gillnet vessel, the F/V Willow was chartered...

Source-to-Sink constraints on tectonic and sedimentary evolution of the Central Range, Cenderawasih Bay (Indonesia) and Gulf of Papua (Papua New Guinea)

Science.gov (United States)

Babault, J.; Viaplana-Muzas, M.; Legrand, X.; Van Den Driessche, J.; González-Quijano, M.; Mudd, S. M.; Kergaravat, C.; Ringenbach, J. C.; Callot, J. P.; Vetel, W.; Dhont, D.

2017-12-01

The island of Papua New Guinea is the result of continent-arc collision that began building the island's Central Range during the late Miocene. The tectono-sedimentary evolution of the Cenderawasih Bay, in the northwestern part of the island of Papua New Guinea (Indonesia), which links the Kepala Burung block to the Central Range is still poorly understood. Previous studies have shown that this bay contains a thick (> 8 km) sequence of undated sediments. Hypothesis claim that the embayment resulted from a 3 Ma aperture created by anticlockwise rotation of the Kepala Burung block with respect to the northern rim of the Australian plate, or from the southwest drift of a slice of volcanics/oceanic crust between 8 and 6 Ma. Using a source-to-sink approach, based on i) a geomorphologic analysis of the drainage network dynamics, ii) a reassessment of available thermochronological data, and iii) seismic lines interpretation, we suggest that sediments started to accumulate in the Cenderawasih Bay and onshore in the Waipoga Basin in the late Miocene since the beginning of the Central Range building at 12 Ma, resulting in sediment accumulation of up to 12200 m. At first order, we predict that infilling is mainly composed of siliciclastics sourced in the graphite-bearing Ruffaer Metamorphic Belt and its equivalent in the Weyland Overthrust. From the unroofing paths in the Central Range we deduce two rates of solid phase accumulation (SPAR) since 12 Ma, the first one at a mean SPAR ranging between 0.12-0.25 mm/a with a maximum SPAR of 0.23-0.58 mm/a, and the second during the last 3 Ma, at a mean SPAR ranging between 0.93-1.62 mm/a and with a maximum SPAR between 2.13-3.17 mm/a, i.e., 6700-10000 m of Plio-Pleistocene sediment accumulation. Local transtensional tectonics may explain these unusually high rates of sedimentation in an overall sinistral oblique convergence setting. We further extended this approach to the Gulf of Papua (Papua New Guinea), a foreland basin developed

Diet of juvenile Alabama shad (Alosa alabamae) in two northern Gulf of Mexico drainages

Science.gov (United States)

Paul F. Mickle; Jacob Schaefer; Donald A. Yee; Susan B. Adams

2013-01-01

Understanding food-web ecology is valuable to conservation by linking interactions of multiple species together and illustrating the functionality of trophic exchange. Alosa alabamae (Alabama Shad), an anadromous species, reproduces in northern Gulf of Mexico drainages from February through May, and for this study, the Pascagoula and Apalachicola...

Baseline concentration of 210Po and 210Pb in Sargassum from the northern Gulf

International Nuclear Information System (INIS)

Uddin, S.; Aba, A.; Bebhehani, M.

2015-01-01

Highlights: • This is the first baseline for 210 Po and 210 Pb in Sargassum from northern Gulf. • 210 Po concentration in Sargassum boveanum is higher than Sargassum oligocystum. • 210 Pb concentrations in two Sargassum species was not statistically significant. • The concentration factor is microalgae is slightly higher than IAEA recommended value. - Abstract: This baseline study highlights the 210 Po and 210 Pb concentration in two species of the benthic macroalgae Sargassum from northern Gulf, also known as the ROPME Sea Area (RSA). Within the marine environment, 210 Po is initially absorbed from water and concentrated by phytoplankton and macroalgae, and this concentrated 210 Po can then readily be passed along to the higher trophic level of the marine food web. The 210 Po concentration measured in Sargassum boveanum (22.5–25.6 Bq kg −1 ) was higher than that in Sargassum oligocystum (20.2–22.5 Bq kg −1 ), but is not statistically significant (p > 0.064), where as the difference between 210 Pb concentrations in Sargassum boveanum (15.3–16.8 Bq kg −1 ) and Sargassum oligocystum (18.4–22.0 Bq kg −1 ) was statistically significant (p > 0.019). The measured concentration factor for 210 Po in Sargassum in the northern Gulf varied between 0.55 and 1.2 × 10 4 , values higher to the IAEA recommended value of 1 × 10 3 . The 210 Po enrichment is observed in both the species of Sargassum, 210 Po/ 210 Pb ratio was >1 at all the stations for all the samples

2007 USGS/NPS/NASA Experimental Advanced Airborne Research Lidar (EAARL): Northern Gulf of Mexico Barrier Islands

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A bare earth elevation map (also known as a Digital Elevation Model, or DEM) of the northern Gulf of Mexico barrier islands and Naval Live Oaks was produced from...

Statistical Models for Sediment/Detritus and Dissolved Absorption Coefficients in Coastal Waters of the Northern Gulf of Mexico

National Research Council Canada - National Science Library

Green, Rebecca E; Gould, Jr., Richard W; Ko, Dong S

2008-01-01

... (CDOM) absorption coefficients from physical hydrographic and atmospheric properties. The models were developed for northern Gulf of Mexico shelf waters using multi-year satellite and physical data...

Metals in Bone Tissue of Antillean Manatees from the Gulf of Mexico and Chetumal Bay, Mexico.

Science.gov (United States)

Romero-Calderón, Ana G; Morales-Vela, Benjamin; Rosíles-Martínez, René; Olivera-Gómez, León D; Delgado-Estrella, Alberto

2016-01-01

Concentrations of seven metals (As, Cd, Cr, Cu, Pb, Ni, and Zn) were analyzed in 33 bone tissue samples of Antillean manatees (Trichechus manatus manatus) found dead in lagoons and rivers of Tabasco and Campeche in the Gulf of Mexico and Chetumal Bay in the Caribbean region. The concentrations of Cr, Cu, Pb, and Zn were significantly different between regions, with greater levels found in the Gulf of Mexico group than in the Mexican Caribbean group (p < 0.05). Pb concentrations differed significantly between adults and calves. No differences were observed between sexes. Metal concentrations detected in the manatee bones were higher than most of those reported for bones in other marine mammals around the world. Future studies are necessary to establish whether the metal concentrations represent a risk to the health of the species.

Influence of Subtropical Jetstream on Arabian Gulf Precipitation

Science.gov (United States)

Sandeep, S.; Pauluis, O.; Ravindran, A. M.; TP, S.

2017-12-01

The Arabian Gulf and surrounding regions are predominantly arid. However, this region hosts a large population due to the intense economic activity that is centered on the exploration of natural resources in and around the Arabian Gulf. Thus, few precipitation events that occur during boreal winter are important for society and ecology of this region. The mechanisms of winter precipitation over the Gulf are not well understood, partly due to a lack of long term meteorological observation. Here we explore the dynamics of Arabian Gulf winter precipitation events using available observations and a high resolution atmospheric model simulation. Our analyses show that the northern Gulf receives about six times more precipitation than the southern Gulf. Often, the southern Gulf precipitation forms as a result of downstream development of northern Gulf disturbance. The southward movement of northern Gulf disturbances is influenced by the location of subtropical jet. The probability of a northern Gulf precipitating weather system to move south is higher when the subtropical jet is located equatorward of 30°N. The equatorward position of jet favors the penetration of mid-latitude weather systems over the Arabian Peninsula, which in turn pushes the Arabian anticyclone eastward and triggers moisture transport from the Arabian Sea that is essential for southern Gulf precipitation events.

Introduction to the special issue on “Understanding and predicting change in the coastal ecosystems of the northern Gulf of Mexico”

Science.gov (United States)

Brock, John C.; Barras, John A.; Williams, S. Jeffress

2013-01-01

The coastal region of the northern Gulf of Mexico owes its current landscape structure to an array of tectonic, erosional and depositional, climatic, geochemical, hydrological, ecological, and human processes that have resulted in some of the world's most complex, dynamic, productive, and threatened ecosystems. Catastrophic hurricane landfalls, ongoing subsidence and erosion exacerbated by sea-level rise, disintegration of barrier island chains, and high rates of wetland loss have called attention to the vulnerability of northern Gulf coast ecosystems, habitats, built infrastructure, and economy to natural and anthropogenic threats. The devastating hurricanes of 2005 (Katrina and Rita) motivated the U.S. Geological Survey Coastal and Marine Geology Program and partnering researchers to pursue studies aimed at understanding and predicting landscape change and the associated storm hazard vulnerability of northern Gulf coast region ecosystems and human communities. Attaining this science goal requires increased knowledge of landscape evolution on geologic, historical, and human time scales, and analysis of the implications of such changes in the natural and built components of the landscape for hurricane impact susceptibility. This Special Issue of the Journal of Coastal Research communicates northern Gulf of Mexico research results that (1) improve knowledge of prior climates and depositional environments, (2) assess broad regional ecosystem structure and change over Holocene to human time scales, (3) undertake process studies and change analyses of dynamic landscape components, and (4) integrate framework, climate, variable time and spatial scale mapping, monitoring, and discipline-specific process investigations within interdisciplinary studies.

Parameter sensitivity and identifiability for a biogeochemical model of hypoxia in the northern Gulf of Mexico

Science.gov (United States)

Local sensitivity analyses and identifiable parameter subsets were used to describe numerical constraints of a hypoxia model for bottom waters of the northern Gulf of Mexico. The sensitivity of state variables differed considerably with parameter changes, although most variables ...

Toxicity of weathered Deepwater Horizon oil to bay anchovy (Anchoa mitchilli) embryos.

Science.gov (United States)

O'Shaughnessy, Kathryn A; Forth, Heather; Takeshita, Ryan; Chesney, Edward J

2018-02-01

The BP-contracted Deepwater Horizon Macondo well blowout occurred on 20 April 2010 and lasted nearly three months. The well released millions of barrels of crude oil into the northern Gulf of Mexico, causing extensive impacts on pelagic, benthic, and estuarine fish species. The bay anchovy (Anchoa mitchilli) is an important zooplanktivore in the Gulf, serving as an ecological link between lower trophic levels and pelagic predatory fish species. Bay anchovy spawn from May through November in shallow inshore and estuarine waters throughout the Gulf. Because their buoyant embryos are a dominant part of the inshore ichthyoplankton throughout the summer, it is likely bay anchovy embryos encountered oil in coastal estuaries during the summer and fall of 2010. Bay anchovy embryos were exposed to a range of concentrations of two field-collected Deepwater Horizon oils as high-energy and low-energy water accommodated fractions (HEWAFs and LEWAFs, respectively) for 48h. The median lethal concentrations (LC 50 ) were lower in exposures with the more weathered oil (HEWAF, 1.48µg/L TPAH50; LEWAF, 1.58µg/L TPAH50) compared to the less weathered oil (HEWAF, 3.87µg/L TPAH50; LEWAF, 4.28µg/L TPAH50). To measure delayed mortality and life stage sensitivity between embryos and larvae, an additional 24h acute HEWAF exposure using the more weathered oil was run followed by a 24h grow-out period. Here the LC 50 was 9.71µg/L TPAH50 after the grow-out phase, suggesting a toxic effect of oil at the embryonic or hatching stage. We also found that exposures prepared with the more weathered Slick B oil produced lower LC 50 values compared to the exposures prepared with Slick A oil. Our results demonstrate that even relatively acute environmental exposure times can have a detrimental effect on bay anchovy embryos. Copyright © 2017 Elsevier Inc. All rights reserved.

Coordinated Field Campaigns in Chesapeake Bay and Gulf of Mexico

Science.gov (United States)

Mannino, Antonio; Novak, Michael; Tzortziou, Maria A.

2015-01-01

NASA's GEOstationary Coastal and Air Pollution Events (GEO-CAPE) mission concept recommended by the U.S. National Research Council (2007) focuses on measurements of atmospheric trace gases and aerosols and aquatic coastal ecology and biogeochemistry from geostationary orbit (35,786 km altitude). Two GEO-CAPE-sponsored multi-investigator ship-based field campaigns were conducted to coincide with the NASA Earth Venture Suborbital project DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) field campaigns: (1) Chesapeake Bay in July 2011 and (2) northwestern Gulf of Mexico in September 2013. Goal: to evaluate whether GEO-CAPE coastal mission measurement and instrument requirements are optimized to address science objectives while minimizing ocean color satellite sensor complexity, size and cost - critical mission risk reduction activities. NASA continues to support science studies related to the analysis of data collected as part of these coordinated field campaigns and smaller efforts.

Genetic connectivity in scleractinian corals across the Northern Gulf of Mexico: oil/gas platforms, and relationship to the Flower Garden Banks.

Directory of Open Access Journals (Sweden)

Paul W Sammarco

Full Text Available The 3,000 oil/gas structures currently deployed in the northern Gulf of Mexico (GOM provide hard substratum for marine organisms in a region where such has been rare since the Holocene. The major exception to this are the Flower Garden Banks (FGB. Corals are known to have colonized oil/gas platforms around the FGB, facilitating biogeographic expansion. We ask the question, what are the patterns of genetic affinity in these coral populations. We sampled coral tissue from populations of two species occurring on oil and gas platforms: Madracis decactis (hermatype and Tubastraea coccinea (invasive ahermatype. We sampled 28 platforms along four transects from 20 km offshore to the continental shelf edge off 1 Matagorda Island, TX; 2 Lake Sabine, TX; 3 Terrebonne Bay, LA; and 4 Mobile, AL. The entire population of M. decactis was sampled between depths of 5 m and 37 m. T. coccinea populations were sub-sampled. Genetic variation was assessed using the PCR-based Amplified Fragment Length Polymorphisms (AFLPs. Data were analyzed via AFLPOP and STRUCTURE. Genetic connectivity among M. decactis platform populations was highest near the FGB and decreased to the east. Connectivity increased again in the eastern sector, indicating isolation between the populations from different sides of the Mississippi River (Transects 3 and 4. A point-drop in genetic affinity (relatedness at the shelf edge south of Terrebonne Bay, LA indicated a population differing from all others in the northern GOM. Genetic affinities among T. coccinea were highest in the west and decreased to the east. Very low genetic affinities off Mobile, AL indicated a dramatic difference between those populations and those west of the Mississippi River, apparently a formidable barrier to larval dispersal.

Genetic connectivity in scleractinian corals across the Northern Gulf of Mexico: oil/gas platforms, and relationship to the Flower Garden Banks.

Science.gov (United States)

Sammarco, Paul W; Brazeau, Daniel A; Sinclair, James

2012-01-01

The 3,000 oil/gas structures currently deployed in the northern Gulf of Mexico (GOM) provide hard substratum for marine organisms in a region where such has been rare since the Holocene. The major exception to this are the Flower Garden Banks (FGB). Corals are known to have colonized oil/gas platforms around the FGB, facilitating biogeographic expansion. We ask the question, what are the patterns of genetic affinity in these coral populations. We sampled coral tissue from populations of two species occurring on oil and gas platforms: Madracis decactis (hermatype) and Tubastraea coccinea (invasive ahermatype). We sampled 28 platforms along four transects from 20 km offshore to the continental shelf edge off 1) Matagorda Island, TX; 2) Lake Sabine, TX; 3) Terrebonne Bay, LA; and 4) Mobile, AL. The entire population of M. decactis was sampled between depths of 5 m and 37 m. T. coccinea populations were sub-sampled. Genetic variation was assessed using the PCR-based Amplified Fragment Length Polymorphisms (AFLPs). Data were analyzed via AFLPOP and STRUCTURE. Genetic connectivity among M. decactis platform populations was highest near the FGB and decreased to the east. Connectivity increased again in the eastern sector, indicating isolation between the populations from different sides of the Mississippi River (Transects 3 and 4). A point-drop in genetic affinity (relatedness) at the shelf edge south of Terrebonne Bay, LA indicated a population differing from all others in the northern GOM. Genetic affinities among T. coccinea were highest in the west and decreased to the east. Very low genetic affinities off Mobile, AL indicated a dramatic difference between those populations and those west of the Mississippi River, apparently a formidable barrier to larval dispersal.

The ecosystem baseline for particle flux in the Northern Gulf of Mexico

Directory of Open Access Journals (Sweden)

S.L.C. Giering

2018-01-01

Full Text Available Response management and damage assessment during and after environmental disasters such as the Deepwater Horizon (DWH oil spill require an ecological baseline and a solid understanding of the main drivers of the ecosystem. During the DWH event, a large fraction of the spilled oil was transported to depth via sinking marine snow, a routing of spilled oil unexpected to emergency response planners. Because baseline knowledge of particle export in the Northern Gulf of Mexico and how it varies spatially and temporally was limited, we conducted a detailed assessment of the potential drivers of deep (~1400 m depth particle fluxes during 2012–2016 using sediment traps at three contrasting sites in the Northern Gulf of Mexico: near the DWH site, at an active natural oil seep site, and at a site considered typical for background conditions. The DWH site, located ~70 km from the Mississippi River Delta, showed flux patterns that were strongly linked to the Mississippi nitrogen discharge and an annual subsequent surface bloom. Fluxes carried clear signals of combustion products, which likely originated from pyrogenic sources that were transported offshore via the Mississippi plume. The seep and reference sites were more strongly influenced by the open Gulf of Mexico, did not show a clear seasonal flux pattern, and their overall sedimentation rates were lower than those at the DWH site. At the seep site, based on polycyclic aromatic hydrocarbon data, we observed indications of three different pathways for “natural” oiled-snow sedimentation: scavenging by sinking particles at depth, weathering at the surface before incorporation into sinking particles, and entry into the food web and subsequent sinking in form of detritus. Overall, sedimentation rates at the three sites were markedly different in quality and quantity owing to varying degrees of riverine and oceanic influences, including natural seepage and contamination by combustion products.

Spatial and temporal ecological variability in the northern Gulf of Alaska: What have we learned since the Exxon Valdez oil spill?

Science.gov (United States)

Aderhold, Donna G. R.; Lindeberg, Mandy R.; Holderied, Kris; Pegau, W. Scott

2018-01-01

This special issue examines oceanographic and biological variability in the northern Gulf of Alaska region with an emphasis on recent monitoring efforts of the Gulf Watch Alaska (GWA) and Herring Research and Monitoring (HRM) programs funded by the Exxon Valdez Oil Spill Trustee Council (EVOSTC). These programs are designed to improve our understanding of how changing environmental conditions affect Gulf of Alaska ecosystems and the long-term status of resources injured by the Exxon Valdez oil spill.

Spatial and temporal variability of thermohaline properties in the Bay of Koper (northern Adriatic Sea)

Science.gov (United States)

Soczka Mandac, Rok; Žagar, Dušan; Faganeli, Jadran

2013-04-01

suspended matter. Additionally, we will investigate the cross correlations between the above mentioned parameters with singular value decomposition method. Reference: 1. Faganeli, J., Planinc, R., Pezdic, J., Smodis, B., Stegnar, P., and Ogorelec, B. 1991. Marine geology of Gulf of Trieste (northern Adriatic): Geochemical aspects. Marine Geology, 99: 93-108. 2. Glover, M., Jenkins, J., and Doney, S. C. 2011. Modeling methods for marine science. Cambridge University Press, 571 p.

Structure and petroleum potential of the continental margin between Cross Sound and Icy Bay, northern Gulf of Alaska

Science.gov (United States)

Bruns, T.R.

1982-01-01

Major structural features of the Yakutat segment, the segment of the continental margin between Cross Sound and Icy Bay, northern Gulf of Alaska, are delineated by multichannel seismic reflection data. A large structural high is centered on Fairweather Ground and lies generally at the edge of the shelf from Cross Sound to west of the Alsek Valley. A basement uplift, the Dangerous River zone, along which the seismic acoustic basement shallows by up to two kilometers, extends north from the western edge of Fairweather Ground towards the mouth of the Dangerous River. The Dangerous River zone separates the Yakutat segment into two distinct subbasins. The eastern subbasin has a maximum sediment thickness of about 4 km, and the axis of the basin is near and parallel to the coast. Strata in this basin are largely of late Cenozoic age (Neogene and Quaternary) and approximately correlate with the onshore Yakataga Formation. The western subbasin has a maximum of at least 9 km of sediment, comprised of a thick (greater than 4.5 km) Paleogene section overlain by late Cenozoic strata. The Paleogene section is truncated along the Dangerous River zone by a combination of erosion, faulting, and onlap onto the acoustic basement. Within the western subbasin, the late Cenozoic basin axis is near and parallel to the coast, but the Paleogene basin axis appears to trend in a northwest direction diagonally across the shelf. Sedimentary strata throughout the Yakutat shelf show regional subsidence and only minor deformation except in the vicinity of the Fairweather Ground structural high, near and along the Dangerous River zone, and at the shoreline near Lituya Bay. Seismic data across the continental slope and adjacent deep ocean show truncation at the continental slope of Paleogene strata, the presence of a thick (to 6 km) undeformed or mildly deformed abyssal sedimentary section at the base of the slope that in part onlaps the slope, and a relatively narrow zone along the slope or at

Biomarkers of Aryl-hydrocarbon Receptor Activity in Gulf Killifish (Fundulus grandis) From Northern Gulf of Mexico Marshes Following the Deepwater Horizon Oil Spill.

Science.gov (United States)

Dubansky, Benjamin; Rice, Charles D; Barrois, Lester F; Galvez, Fernando

2017-07-01

Following the Deepwater Horizon oil spill, shorelines throughout the Barataria Basin of the northern Gulf of Mexico in Louisiana were heavily oiled for months with Macondo-252 oil, potentially impacting estuarine species. The Gulf killifish (Fundulus grandis) has been identified as a sentinel species for the study of site-specific effects of crude oil contamination on biological function. In November and December 2010, 4-5 months after the Macondo well was plugged and new oil was no longer spilling into the Gulf waters, Gulf killifish were collected across the Barataria Basin from 14 sites with varying degrees of oiling. Fish collected from oiled sites exhibited biological indications of exposure to oil, including increase in cytochrome P4501A (CYP1A) mRNA transcript and protein abundances in liver tissues. Immunohistochemistry revealed increases in gill, head kidney, and intestinal CYP1A protein at heavily oiled sites. Intestinal CYP1A protein was a sensitive indicator of exposure, indicating that intestinal tissue plays a key role in biotransformation of AHR ligands and that ingestion is a probable route of exposure, warranting additional consideration in future studies.

Methylmercury in the Gulf of Trieste (Northern Adriatic Sea: From Microbial Sources to Seafood Consumers

Directory of Open Access Journals (Sweden)

Mark E. Hines

2014-01-01

Full Text Available The Gulf of Trieste (northern Adriatic Sea is one of the most mercury-polluted areas in the Mediterranean and in the world due to the past mining activity in the Idrija region (western Slovenia. The link between microbial production of toxic methylmercury (MeHg, and its bioaccumulation and biomagnification in marine food webs of the gulf is at present rather poorly characterized but is critical to understanding the links between sources and higher trophic levels, such as fish, that are ultimately vectors of human and wildlife exposure. This overview explores three major topics: (i the microbial biogeochemical cycling of Hg in the area, (ii the trophic transfer and bioaccumulation of MeHg in pelagic and benthic marine food webs, and (iii human exposure to Hg through marine fish and shellfish consumption. These are important goals since the Gulf of Trieste is an area of great economical importance.

50 CFR 226.214 - Critical habitat for Gulf sturgeon.

Science.gov (United States)

2010-10-01

... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS DESIGNATED CRITICAL HABITAT § 226.214... Sound or the Gulf of Mexico. The Withlacoochee River main stem from Florida State Road 6, Madison and...) Unit 11: Florida Nearshore Gulf of Mexico Unit in Escambia, Santa Rosa, Okaloosa, Walton, Bay, and Gulf...

Trace elements and heavy metals in the Grand Bay National Estuarine Reserve in the northern Gulf of Mexico

Science.gov (United States)

The Grand Bay National Estuarine Research Reserve has the highest biotic diversity of habitats and offer a reserve of food resources and commercially significant species. Rapid human civilization has led to accumulation of heavy metals and trace elements in estuaries. The Grand Bay National Estuarin...

Contaminant transport in Massachusetts Bay

Science.gov (United States)

Butman, Bradford

Construction of a new treatment plant and outfall to clean up Boston Harbor is currently one of the world's largest public works projects, costing about $4 billion. There is concern about the long-term impact of contaminants on Massachusetts Bay and adjacent Gulf of Maine because these areas are used extensively for transportation, recreation, fishing, and tourism, as well as waste disposal. Public concern also focuses on Stellwagen Bank, located on the eastern side of Massachusetts Bay, which is an important habitat for endangered whales. Contaminants reach Massachusetts Bay not only from Boston Harbor, but from other coastal communities on the Gulf of Maine, as well as from the atmosphere. Knowledge of the pathways, mechanisms, and rates at which pollutants are transported throughout these coastal environments is needed to address a wide range of management questions.

Satellite images survey for the identification of the coastal sedimentary system changes and associated vulnerability along the western bay of the Gulf of Tunis (northern Africa)

Science.gov (United States)

Hzami, Abderraouf; Amrouni, Oula; Romanescu, Gheorghe; Constantin Stoleriu, Cristian; Mihu-Pintilie, Alin; Saâdi, Abdeljaouad

2018-04-01

The aim of this study consists in testing the effectiveness of satellite data in order to monitoring shoreline and sedimentary features changes, especially the rapidly changing of Gulf of Tunis coast. The study area is located in the Gulf of Tunis western bay (Southern Mediterranean Sea) which is characterized by sandy beaches of Ghar Melah and Raoued (Medjerda Delta area). The aerial photographs and satellite imageries were used for mapping the evolution of shoreline. Diachronic data (satellite imagery, aerial photography and topographic maps) were used to monitor and to quantify, the evolution of the coastal areas. These thematic data were digitally overlaid and vectorised for highlighting the shoreline changes between 1936 and 2016, in order to map the rate of erosion and accretion along the shoreline. Results show that the accretion and degradation are related to the Medjerda: change of outlet in 1973 and impoundment of the Sidi Salem dam in 1982. We found that the general trend of the coastal geomorphic processes can be monitored with satellite imageries (such as Sentinel A2, Spots 4 and 5), due to its repetitive coverage along the time and their high quality concerning the spectral contrast between land and sea areas. Improved satellite imageries with high resolution should be a valuable tool for complementing traditional methods for mapping and assessing the sedimentary structures (such as shoreline, delta, marine bars), and monitoring especially the lowlands coastal areas (slightly eroded).

Establishing a baseline of estuarine submerged aquatic vegetation resources across salinity zones within coastal areas of the northern Gulf of Mexico

Science.gov (United States)

Hillmann, Eva R.; DeMarco, Kristin; LaPeyre, Megan K.

2016-01-01

Coastal ecosystems are dynamic and productive areas that are vulnerable to effects of global climate change. Despite their potentially limited spatial extent, submerged aquatic vegetation (SAV) beds function in coastal ecosystems as foundation species, and perform important ecological services. However, limited understanding of the factors controlling SAV distribution and abundance across multiple salinity zones (fresh, intermediate, brackish, and saline) in the northern Gulf of Mexico restricts the ability of models to accurately predict resource availability. We sampled 384 potential coastal SAV sites across the northern Gulf of Mexico in 2013 and 2014, and examined community and species-specific SAV distribution and biomass in relation to year, salinity, turbidity, and water depth. After two years of sampling, 14 species of SAV were documented, with three species (coontail [Ceratophyllum demersum], Eurasian watermilfoil [Myriophyllum spicatum], and widgeon grass [Ruppia maritima]) accounting for 54% of above-ground biomass collected. Salinity and water depth were dominant drivers of species assemblages but had little effect on SAV biomass. Predicted changes in salinity and water depths along the northern Gulf of Mexico coast will likely alter SAV production and species assemblages, shifting to more saline and depth-tolerant assemblages, which in turn may affect habitat and food resources for associated faunal species.

Distribution and dynamic habitat use of young bull sharks Carcharhinus leucas in a highly stratified northern Gulf of Mexico estuary.

Directory of Open Access Journals (Sweden)

J Marcus Drymon

Full Text Available Understanding how animals alter habitat use in response to changing abiotic conditions is important for effective conservation management. For bull sharks (Carcharhinus leucas, habitat use has been widely examined in the eastern and western Gulf of Mexico; however, knowledge of their movements and the factors influencing them is lacking for populations in the more temperate north-central Gulf of Mexico. To examine how changes in hydrographic conditions affected the presence of young bull sharks in Mobile Bay, Alabama, thirty-five sharks were fitted with internal acoustic transmitters and monitored with an acoustic monitoring array consisting of thirty-three receivers between June 2009 and December 2010. Tagged sharks ranged in size from 60 to 114 cm fork length and were detected between the upper and lower portions of Mobile Bay. Despite a variety of freshwater sources associated with this highly productive estuary, sharks were most consistently detected at the largest input to the system--the Mobile and Tensaw Rivers. Our findings suggest a combination of hydrographic factors interact to influence the distribution of juvenile bull sharks in Mobile Bay. The factors affecting the probability of detecting at least one bull shark varied both temporally (2009 vs 2010 and spatially (upper vs lower bay. Electivity analysis demonstrated that bull sharks showed highest affinity for warm water (29-32 °C, moderate salinities (10-11 psu and normoxic waters (5-7 mg/l, although these patterns were not consistent between regions or across years. We suggest future studies coupling telemetry and hydrographic variables should, when possible, consider the interactions of multiple environmental parameters when defining the dynamic factors explaining the spatial distribution of coastal sharks.

Distribution and dynamic habitat use of young bull sharks Carcharhinus leucas in a highly stratified northern Gulf of Mexico estuary.

Science.gov (United States)

Drymon, J Marcus; Ajemian, Matthew J; Powers, Sean P

2014-01-01

Understanding how animals alter habitat use in response to changing abiotic conditions is important for effective conservation management. For bull sharks (Carcharhinus leucas), habitat use has been widely examined in the eastern and western Gulf of Mexico; however, knowledge of their movements and the factors influencing them is lacking for populations in the more temperate north-central Gulf of Mexico. To examine how changes in hydrographic conditions affected the presence of young bull sharks in Mobile Bay, Alabama, thirty-five sharks were fitted with internal acoustic transmitters and monitored with an acoustic monitoring array consisting of thirty-three receivers between June 2009 and December 2010. Tagged sharks ranged in size from 60 to 114 cm fork length and were detected between the upper and lower portions of Mobile Bay. Despite a variety of freshwater sources associated with this highly productive estuary, sharks were most consistently detected at the largest input to the system--the Mobile and Tensaw Rivers. Our findings suggest a combination of hydrographic factors interact to influence the distribution of juvenile bull sharks in Mobile Bay. The factors affecting the probability of detecting at least one bull shark varied both temporally (2009 vs 2010) and spatially (upper vs lower bay). Electivity analysis demonstrated that bull sharks showed highest affinity for warm water (29-32 °C), moderate salinities (10-11 psu) and normoxic waters (5-7 mg/l), although these patterns were not consistent between regions or across years. We suggest future studies coupling telemetry and hydrographic variables should, when possible, consider the interactions of multiple environmental parameters when defining the dynamic factors explaining the spatial distribution of coastal sharks.

Statistical properties of the surface velocity field in the northern Gulf of Mexico sampled by GLAD drifters

NARCIS (Netherlands)

Mariano, A.J.; Ryan, E.H.; Huntley, H.S.; Laurindo, L.C.; Coelho, E.; Ozgokmen, TM; Berta, M.; Bogucki, D; Chen, S.S.; Curcic, M.; Drouin, K.L.; Gough, M; Haus, BK; Haza, A.C.; Hogan, P; Iskandarani, M; Jacobs, G; Kirwan Jr., A.D.; Laxague, N; Lipphardt Jr., B.; Magaldi, M.G.; Novelli, G.; Reniers, A.J.H.M.; Restrepo, J.M.; Smith, C; Valle-Levinson, A.; Wei, M.

2016-01-01

The Grand LAgrangian Deployment (GLAD) used multiscale sampling and GPS technology to observe time series of drifter positions with initial drifter separation of O(100 m) to O(10 km), and nominal 5 min sampling, during the summer and fall of 2012 in the northern Gulf of Mexico. Histograms of the

Contamination of harbor sediments in the eastern Gulf of Finland (Neva Bay), Baltic Sea

Energy Technology Data Exchange (ETDEWEB)

Ussenkov, S.M. [Dept. of Lithology and Marine Geology, Faculty of Geology, St. Petersburg State Univ. (Russian Federation)

1997-11-01

The areal distribution of oil products and various trace metals have been studied in bottom surface deposits from the harbors of Neva Bay. The data of contents were normalized to natural background concentrations. Also the size and biomass of benthos groups were analyzed. The results show clearly that industrial discharges have elevated levels of contamination in the sediments. Few efficient measures against environmental contamination have been taken. The sediments contain very high concentrations of oil products and such heavy metals as Hg, Pb, Cu, and Zn. The benthic organisms most sensitive to heavy metal contamination are Chironomidae. The dredging and dumping of the contaminated deposits can lead to secondary contamination of the Gulf of Finland and the Baltic proper. (orig.)

Near-coastal ocean variability off southern Tamaulipas - northern Veracruz, western Gulf of Mexico, during spring-summer 2013

Science.gov (United States)

Rivas, David

2016-04-01

Six months of observations from a near-coastal mooring deployed off southern Tamaulipas-northern Veracruz coast (western Gulf of Mexico) during spring-summer 2013 provides velocity, temperature, salinity, sea level, and dissolved oxygen series in a region which ocean dynamics is still poorly understood. As shown in a preceding analysis of this region's winter circulation for winter 2012-2013, coastal trapped motions associated with the regional invasion of synoptic cold fronts modulate the local variability; this pattern remains in the spring 2013, when even more intense events of alongshore flow (>50 cm/s) are observed. This intensified flow is associated with a significant decrease in the dissolved oxygen, most probably related to an influence of hypoxic waters coming from the northern Gulf. In late spring-mid summer, the wind pattern corresponds to persistent southeasterly winds that favor the occurrence of a local upwelling, which maintains a local thermal reduction (>3 degrees Celsius) and is associated with a persistent northward flow (>30 cm/s). The late summer was characterized by a significant tropical-cyclone activity, when a depression, a storm, and a hurricane affected the western Gulf. These tropical systems caused an intense precipitation and hence an important intensification of the local riverine discharge, and the winds enhanced the mixing of such riverine waters, via mostly kinetic stirring and Ekman pumping.

Radon concentration and its relation with some environmental conditions in the northern safaga bay

International Nuclear Information System (INIS)

Al-Arabi, A.M.; Tartor, B.A.; Bashter, I.I.; El-Saman, M.I.; Maiyza, I.A.

2005-01-01

The coastal zone along the Red Sea at Safaga town is a site for industrial development and accepting future establishment of dense recreational resorts. It includes Safaga harbour in which international trade depends. Until now most of the coastal area at Safaga is pristine and suffering from continuous increasing population densities. There is no idea about the distribution of hydro graphic parameters or radon level in the northern Safaga bay in spite of the area famous as the treatment area for Psoriases and Rheumatoid as will as attractive area for tourism. The relative high relations exist between the radioactivity component and the ph, specific conductivity, water salinity, water density and dissolved oxygen were calculated. The concentration of 226 R a, 232 T h and 40 K in sediment samples collected from bottom of the northern Safaga Bay fluctuated between 5 to 19 Bq.kg-1, 4 to 19 Bq.kg-1 and 1545 to 6122 Bq.kg-1, respectively. Whereas the concentration of radon air varies between 2 -11 Bq.cm-3

Oil & Natural Gas Technology A new approach to understanding the occurrence and volume of natural gas hydrate in the northern Gulf of Mexico using petroleum industry well logs

Energy Technology Data Exchange (ETDEWEB)

Cook, Ann [The Ohio State Univ., Columbus, OH (United States); Majumdar, Urmi [The Ohio State Univ., Columbus, OH (United States)

2016-03-31

The northern Gulf of Mexico has been the target for the petroleum industry for exploration of conventional energy resource for decades. We have used the rich existing petroleum industry well logs to find the occurrences of natural gas hydrate in the northern Gulf of Mexico. We have identified 798 wells with well log data within the gas hydrate stability zone. Out of those 798 wells, we have found evidence of gas hydrate in well logs in 124 wells (15% of wells). We have built a dataset of gas hydrate providing information such as location, interval of hydrate occurrence (if any) and the overall quality of probable gas hydrate. Our dataset provides a wide, new perspective on the overall distribution of gas hydrate in the northern Gulf of Mexico and will be the key to future gas hydrate research and prospecting in the area.

A Stock Assessment of the Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758) for Sustainable Management in Kung Krabaen Bay, Gulf of Thailand.

Science.gov (United States)

Kunsook, Chutapa; Gajaseni, Nantana; Paphavasit, Nittharatana

2014-08-01

A stock assessment of blue swimming crabs, Portunus pelagicus was conducted with crab gill nets and collapsible crab traps at Kung Krabaen Bay, in the eastern Gulf of Thailand, from 2008 to 2009. Several key indicators show that P. pelagicus population is in crisis. Fishing mortality shows an increase to 4.14. The exploitation rate is 0.71, higher than the optimal value of 0.38. The size of the mature females has also decreased from 8.10±0.39 cm to 7.52±1.14 cm. The average fecundity is 0.572×10(6)±0.261×10(6) eggs per batch, and the sex ratio (male:female) is 1:0.92. Based on these results, a sustainable management program for P. pelagicus was proposed as follows: (i) closing the bay during the spawning season, (ii) restoration of the Enhalus acoroides seagrass beds, (iii) restocking crab larvae in the bay and (iv) educating and networking all stakeholders to develop a better understanding of the ecology of the crab to support sustainable fishery management in Kung Krabaen Bay.

Baseline concentration of {sup 210}Po in Sargassum from the Northern Gulf

Energy Technology Data Exchange (ETDEWEB)

Uddin, S.; Bebhehani, M.; Talebi, L. [Kuwait Institute for Scientific Research (Kuwait)

2014-07-01

The concentration of the {sup 210}Po is of enormous interest because of its large contribution to the natural radiation dose received by marine organisms and human populations consuming seafood. In fact natural {sup 210}Po is responsible for higher radiation doses to humans consuming marine products than is plutonium and other man-made radionuclides. Many marine organisms are capable of concentrating {sup 210}Po in their tissues. {sup 210}Po is an alpha emitter in the {sup 238}U series, with 138-d half-life, that is supplied to seawater from atmospheric inputs and river runoff, however, the main source of {sup 210}Po in the environment is {sup 222}Rn exhalation from the ground. Assessing the impact of radionuclides in the environment requires the establishment of baseline levels in the environmental compartments. The objective of this study was to establish baseline levels in Sargassum. Two most common species of Sargassum found in the northern Gulf were analysed for {sup 210}Po. These macro-algae were collected from three different locations during January 2013. This study sets the baseline for {sup 210}Po concentration in northern Gulf, {sup 210}Po is absorbed from water and concentrated by Phytoplankton and macro-algae. This concentrated {sup 210}Po can then be passed along to the next trophic level of the marine food web. The {sup 210}Po concentration measured in Sargassum boveanum (4.405 - 4.952 BqKg{sup -1}) was significantly higher (p>0.084) than Sargassum oligocystum (3.838 - 4.358 BqKg{sup -1}). The {sup 210}Po concentration in these seaweeds from the Arabian/Persian Gulf were substantially lower than those found in various Phytoplankton and macro-algae species from other regions; this may be due to the lower background {sup 210}Po concentration in the Kuwait marine waters (0.282 - 0.382 mBq l{sup -1}). The {sup 210}Po concentrations in seawater measured at the 3 stations during January 2013 were less than those reported previously from the same region

Assessment of seismic hazards along the northern Gulf of Aqaba

Science.gov (United States)

Abueladas, Abdel-Rahman Aqel

Aqaba and Elat are very important port and recreation cities for the Hashemite Kingdom of Jordan and Israel, respectively. The two cities are the most susceptible to damage from a destructive future earthquake because they are located over the tectonically active Dead Sea transform fault (DST) that is the source of most of the major historical earthquakes in the region. The largest twentieth century earthquake on the DST, the magnitude Mw 7.2 Nuweiba earthquake of November 22, 1995, caused damage to structures in both cities. The integration of geological, geophysical, and earthquake engineering studies will help to assess the seismic hazards by determining the location and slip potential of active faults and by mapping areas of high liquefaction susceptibility. Ground Penetrating Radar (GPR) as a high resolution shallow geophysical tool was used to map the shallow active faults in Aqaba, Taba Sabkha area, and Elat. The GPR data revealed the onshore continuation of the Evrona, West Aqaba, Aqaba fault zones, and several transverse faults. The integration of offshore and onshore data confirm the extension of these faults along both sides of the Gulf of Aqaba. A 3D model of GPR data at one site in Aqaba indicates that the NW-trending transverse faults right laterally offset older than NE-trending faults. The most hazardous fault is the Evrona fault which extends north to the Tabs Sabkha. A geographic information system (GIS) database of the seismic hazard was created in order to facilitate the analyzing, manipulation, and updating of the input parameters. Liquefaction potential maps were created for the region based on analysis of borehole data. The liquefaction map shows high and moderate liquefaction susceptibility zones along the northern coast of the Gulf of Aqaba. In Aqaba several hotels are located within a high and moderate liquefaction zones. The Yacht Club, Aqaba, Ayla archaeological site, and a part of commercial area are also situated in a risk area. A part

Chesapeake Bay plume dynamics from LANDSAT

Science.gov (United States)

Munday, J. C., Jr.; Fedosh, M. S.

1981-01-01

LANDSAT images with enhancement and density slicing show that the Chesapeake Bay plume usually frequents the Virginia coast south of the Bay mouth. Southwestern (compared to northern) winds spread the plume easterly over a large area. Ebb tide images (compared to flood tide images) show a more dispersed plume. Flooding waters produce high turbidity levels over the shallow northern portion of the Bay mouth.

Application of biomarkers in Epaulet grouper (Epinephelus stoliczkae) to assess chromium pollution in the Chabahar Bay and Gulf of Oman

International Nuclear Information System (INIS)

Sadeghi, Parvin; Kazerouni, Faranak; Savari, Ahmad; Movahedinia, Abdolali; Safahieh, Alireza; Ajdari, Daniel

2015-01-01

In the present study plasma levels of erythropoietin (EPO) hormone and kidney histological changes were assessed as biomarkers to evaluate the chromium pollution in Epaulet grouper (Epinephelus stoliczkae) obtained from different areas in Chabahar Bay and Gulf of Oman. Chemical analyses included the evaluation of chromium in the fish kidney tissue and sediment. The highest and lowest concentrations of chromium were measured in the kidney of fish and sediment collected from Konarak (47.53 ± 1.23 and 110 ± 1.4 μg g –1 ) and the mouth of Chabahar Bay (3.43 ± 1.31 and 13.5 ± 3.23 μg g –1 ), respectively. There was significant difference (P < 0.05) of EPO plasma levels between Konarak, Beris and Ramin stations with the mouth of Chabahar Bay as the cleanest station. Reduction of Bowman's space, occlusion of the tubule lumen, leukocytes infiltration, melanomacrophage centers aggregation, nuclear vacuolation, nuclei hypertrophy of tubule cells, necrosis of the tubules, lifting of the tubular basement membrane and dilatation of glomerular capillaries were the most alterations observed in the kidney. The HAI values of Epaulet grouper from Konarak, Beris and Ramin stations were significantly higher than other stations (P < 0.05). It was concluded that selected biomarkers as a first investigation could be useful tools to environmental biomonitoring programs. - Highlights: • Plasma EPO level and kidney HAI were assessed as Cr biomarkers in E. stoliczkae. • Chromium was measured in the sediment and kidney of E. stoliczkae in the Gulf of Oman. • Highest Cr concentration was in the sediment and E. stoliczkae kidney from Konarak. • The analyzed biomarkers in E. stoliczkae are suitable to monitor Cr pollution

Application of biomarkers in Epaulet grouper (Epinephelus stoliczkae) to assess chromium pollution in the Chabahar Bay and Gulf of Oman

Energy Technology Data Exchange (ETDEWEB)

Sadeghi, Parvin, E-mail: parvin.sadeghi@gmail.com [Marine Biology Department, Marine Science Faculty, Chabahar Maritime University, Chabahar (Iran, Islamic Republic of); Kazerouni, Faranak [Department of Laboratory Medicine, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of); Savari, Ahmad; Movahedinia, Abdolali; Safahieh, Alireza [Marine Biology Department, Marine and Oceanic Science Faculty, Khorramshahr University of Marine Science and Technology, Khorramshahr (Iran, Islamic Republic of); Ajdari, Daniel [Iranian Fisheries Research Organization, Tehran (Iran, Islamic Republic of)

2015-06-15

In the present study plasma levels of erythropoietin (EPO) hormone and kidney histological changes were assessed as biomarkers to evaluate the chromium pollution in Epaulet grouper (Epinephelus stoliczkae) obtained from different areas in Chabahar Bay and Gulf of Oman. Chemical analyses included the evaluation of chromium in the fish kidney tissue and sediment. The highest and lowest concentrations of chromium were measured in the kidney of fish and sediment collected from Konarak (47.53 ± 1.23 and 110 ± 1.4 μg g{sup –1}) and the mouth of Chabahar Bay (3.43 ± 1.31 and 13.5 ± 3.23 μg g{sup –1}), respectively. There was significant difference (P < 0.05) of EPO plasma levels between Konarak, Beris and Ramin stations with the mouth of Chabahar Bay as the cleanest station. Reduction of Bowman's space, occlusion of the tubule lumen, leukocytes infiltration, melanomacrophage centers aggregation, nuclear vacuolation, nuclei hypertrophy of tubule cells, necrosis of the tubules, lifting of the tubular basement membrane and dilatation of glomerular capillaries were the most alterations observed in the kidney. The HAI values of Epaulet grouper from Konarak, Beris and Ramin stations were significantly higher than other stations (P < 0.05). It was concluded that selected biomarkers as a first investigation could be useful tools to environmental biomonitoring programs. - Highlights: • Plasma EPO level and kidney HAI were assessed as Cr biomarkers in E. stoliczkae. • Chromium was measured in the sediment and kidney of E. stoliczkae in the Gulf of Oman. • Highest Cr concentration was in the sediment and E. stoliczkae kidney from Konarak. • The analyzed biomarkers in E. stoliczkae are suitable to monitor Cr pollution.

Propagation of Tsunami-like Surface Long Waves in the Bays of a Variable Depth

Directory of Open Access Journals (Sweden)

A.Yu. Bazykina

2016-08-01

Full Text Available Within the framework of the nonlinear long wave theory the regularities of solitary long wave propagation in the semi-closed bays of model and real geometry are numerically studied. In the present article the zones of wave amplification in the bay are found. The first one is located near the wave running-up on the beach (in front of the bay entrance and the other one – in the middle part of the sea basin. Wave propagation in these zones is accompanied both by significant rise and considerable fall of the sea level. Narrowing of the bay entrance and increase of the entering wave length result in decrease of the sea level maximum rises and falls. The Feodosiya Gulf in the Black Sea is considered as a real basin. In general the dynamics of the waves in the gulf is similar to wave dynamics in the model bay. Four zones of the strongest wave amplification in the Feodosiya Gulf are revealed in the article. The sea level maximum rises and extreme falls which tend to grow with decrease of the entering wave length are observed in these zones. The distance traveled by the wave before the collapse (due to non-linear effects, was found to reduce with decreasing wavelength of the entrance to the bay (gulf.

Organochlorines in harbor seal (Phoca vitulina) tissues from the northern Gulf of Alaska

International Nuclear Information System (INIS)

Wang Dongli; Atkinson, Shannon; Hoover-Miller, Anne; Lee, Sung-Eun; Li, Qing X.

2007-01-01

Polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its metabolites, heptachlor and hexachlorocyclohexanes (HCHs) were analyzed in the harbor seal (Phoca vitulina) tissues collected from the Gulf of Alaska during 2000-2001. ΣPCBs (16-728 ng/g lw) and ΣDDTs (14-368 ng/g lw) were the predominant pollutants followed by ΣHCHs (0.56-93 ng/g lw) and heptachlor (≤0.068-6.0 ng/g lw). Concentrations of the above organochlorines (OCs) in the liver, kidney and blubber tissues correlated with ages, sex, body weight and blubber thickness of the harbor seals. The OC concentrations were similar between the samples collected from two different regions - Prince William Sound, and Kodiak Island and Southern Alaska Peninsula. Mean levels of OCs in nursing female adults were much lower than those in male adults, which indicate that lactation transfer OCs from mother seals to newborns. - Σ28 PCB congeners, p,p'-DDE, p,p'-DDD and p,p'-DDT, α-, β-, γ-, and δ-HCH and heptachlor in harbor seal tissues from the northern Gulf of Alaska are reported

Effects of ocean acidification on single and mixed seagrass species meadows in estuarine waters of the Northern Gulf of Mexico

Science.gov (United States)

In an outdoor mesocosm, we tested the hypothesis that OA would benefit seagrasses in mesohaline waters of the Northern Gulf of Mexico in homo- and hetero- specific seagrass beds of Halodule wrightii and Ruppia maritima. In this estuarine environment, short-term increases in CO2 ...

Photophysiological and light absorption properties of phytoplankton communities in the river-dominated margin of the northern Gulf of Mexico

Science.gov (United States)

Chakraborty, Sumit; Lohrenz, Steven E.; Gundersen, Kjell

2017-06-01

Spatial and temporal variability in photophysiological properties of phytoplankton were examined in relationship to phytoplankton community composition in the river-dominated continental margin of the northern Gulf of Mexico (NGOM). Observations made during five research cruises in the NGOM included phytoplankton photosynthetic and optical properties and associated environmental conditions and phytoplankton community structure. Distinct patterns of spatial and temporal variability in photophysiological parameters were found for waters dominated by different phytoplankton groups. Photophysiological properties for locations associated with dominance by a particular group of phytoplankton showed evidence of photoacclimation as reflected by differences in light absorption and pigment characteristics in relationship to different light environments. The maximum rate of photosynthesis normalized to chlorophyll (PmaxB) was significantly higher for communities dominated (>60% biomass) by cyanobacteria + prochlorophyte (cyano + prochl). The initial slope of the photosynthesis-irradiance (P-E) curve normalized to chlorophyll (αB) was not clearly related to phytoplankton community structure and no significant differences were found in PmaxB and αB between different geographic regions. In contrast, maximum quantum yield of carbon fixation in photosynthesis (Φcmax) differed significantly between regions and was higher for diatom-dominated communities. Multiple linear regression models, specific for the different phytoplankton communities, using a combination of environmental and bio-optical proxies as predictor variables showed considerable promise for estimation of the photophysiological parameters on a regional scale. Such an approach may be utilized to develop size class-specific or phytoplankton group-specific primary productivity models for the NGOM.Plain Language SummaryThis study examined the relationships between phytoplankton community composition and associated

Understanding Global Supply Chains and Seafood Markets for the Rebuilding Prospects of Northern Gulf Cod Fisheries

Directory of Open Access Journals (Sweden)

Ahmed S. Khan

2012-11-01

Full Text Available Although fisheries production and seafood trade are global in scope, with billions of dollars in exports, the rebuilding of collapsed fisheries often focus on national fisheries policy and management measures, with little attention to global supply chains and international consumer markets. Even with two moratoria and two decades of policy changes since the Northern Gulf cod fisheries collapsed in eastern Canada, rebuilding has stalled and the fishing industry and coastal communities continue to undergo challenges with economic viability and resource sustainability. This paper examines and analyzes the global supply chain and marketing dimension of Northern Gulf cod fisheries. Drawing upon fisheries bioeconomics and governance theory, a pre- and post-collapse analysis is undertaken to understand key drivers and institutional mechanisms along global fish supply chains for an effective and successful rebuilding. Findings indicate that the collapse of the cod fishery has cascading effects that go beyond ecosystem changes to new harvesting activities, industry restructuring, supply chain reorganization, new global markets and consumer preference for certified seafood. This suggests that a holistic rebuilding approach is necessary, one that integrates institutional and behavioral changes for both producers and consumers at various scales of fisheries production, political economy issues, as well as cross-scale policies on marine conservation and regional economic development.

Feeding habits and stomach contents of silver sillago, Sillago sihama, in the northern Persian Gulf

OpenAIRE

Taghavi Motlagh, A.; Hakimelahi, M.; Ghodrati Shojaei, M.; Vahabnezhad, A.; Taheri Mirghaed, A.

2012-01-01

The study investigated the stomach content of Sillago sihama in Hormuzgan Province waters located in the northern Persian Gulf from October 2009 to March 2010. The stomach analysis was carried out using frequency of occurrence and numeric methods. Diatoms, blue-green algae and dinoflagellates constituted main food of plant origin. Diatoms were found to be the most preferable food of plant origin where it occurred in more than 60.8% of food item by number and 59.5% by occurrence. Crustacean in...

Natural Sunlight Shapes Crude Oil-Degrading Bacterial Communities in Northern Gulf of Mexico Surface Waters

OpenAIRE

Bacosa, Hernando P.; Liu, Zhanfei; Erdner, Deana L.

2015-01-01

Following the Deepwater Horizon (DWH) spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH ...

Structural setting and evolution of the Mensa and Thunder Horse intraslope basins, northern deep-water Gulf of Mexico: A case study

NARCIS (Netherlands)

Weimer, P.; Bouroullec, R.; Berg, A.A. van den; Lapinski, T.G.; Roesink, J.G.; Adson, J.

2017-01-01

The Mensa and Thunder Horse intraslope minibasins in southcentralMississippi Canyon, northern deep-water Gulf ofMexico, had a linked structural evolution from the Early Cretaceous through the late Miocene. Analysis of the two minibasins illustrates the complexities of deep-water sedimentation and

Potential Connectivity of Coldwater Black Coral Communities in the Northern Gulf of Mexico

Science.gov (United States)

Cardona, Yuley; Ruiz-Ramos, Dannise V.; Baums, Iliana B.; Bracco, Annalisa

2016-01-01

The black coral Leiopathes glaberrima is a foundation species of deep-sea benthic communities but little is known of the longevity of its larvae and the timing of spawning because it inhabits environments deeper than 50 m that are logistically challenging to observe. Here, the potential connectivity of L. glaberrima in the northern Gulf of Mexico was investigated using a genetic and a physical dispersal model. The genetic analysis focused on data collected at four sites distributed to the east and west of Mississippi Canyon, provided information integrated over many (~10,000) generations and revealed low but detectable realized connectivity. The physical dispersal model simulated the circulation in the northern Gulf at a 1km horizontal resolution with transport-tracking capabilities; virtual larvae were deployed 12 times over the course of 3 years and followed over intervals of 40 days. Connectivity between sites to the east and west of the canyon was hampered by the complex bathymetry, by differences in mean circulation to the east and west of the Mississippi Canyon, and by flow instabilities at scales of a few kilometers. Further, the interannual variability of the flow field surpassed seasonal changes. Together, these results suggest that a) dispersal among sites is limited, b) any recovery in the event of a large perturbation will depend on local larvae produced by surviving individuals, and c) a competency period longer than a month is required for the simulated potential connectivity to match the connectivity from multi-locus genetic data under the hypothesis that connectivity has not changed significantly over the past 10,000 generations. PMID:27218260

DNA barcoding and morphological studies confirm the occurrence of three Atarbolana (Crustacea: Isopoda: Cirolanidae) species along the coastal zone of the Persian Gulf and Gulf of Oman.

Science.gov (United States)

Khalaji-Pirbalouty, Valiallah; Raupach, Michael J

2016-11-27

Two species of Atarbolana (Cirolanidae: Isopoda) from the intertidal zone of the Gulf of Oman and the Persian Gulf were studied and redescribed. The known distribution of this small genus is limited to the northern areas of the Indian Ocean, from the Pakistan coasts to the Persian Gulf. The analyses of DNA barcodes as well as detailed morphological studies clearly support the existence of three distinct Atarbolana species along the coastal zone of the Persian Gulf and northern Arabian Sea. Furthermore, A. dasycolus Yasmeen, 2004 is synonymized with A. setosa Javed and Yasmeen, 1989.

Tectonoestratigraphic and Thermal Models of the Tiburon and Wagner Basins, northern Gulf of California Rift System

Science.gov (United States)

Contreras, J.; Ramirez Zerpa, N. A.; Negrete-Aranda, R.

2014-12-01

The northern Gulf of California Rift System consist sofa series faults that accommodate both normal and strike-slip motion. The faults formed a series of half-greens filled with more than 7 km of siliciclastic suc­cessions. Here, we present tectonostratigraphic and heat flow models for the Tiburón basin, in the southern part of the system, and the Wag­ner basin in the north. The models are constrained by two-dimensional seis­mic lines and by two deep boreholes drilled by PEMEX­-PEP. Analysis of the seismic lines and models' results show that: (i) subsidence of the basins is controlled by high-angle normal faults and by flow of the lower crust, (ii) basins share a common history, and (iii) there are significant differences in the way brittle strain was partitioned in the basins, a feature frequently observed in rift basins. On one hand, the bounding faults of the Tiburón basin have a nested geometry and became active following a west-to-east sequence of activation. The Tiburon half-graben was formed by two pulses of fault activity. One took place during the protogulf extensional phase in the Miocene and the other during the opening of Gulf of California in the Pleistocene. On the other hand, the Wagner basin is the result of two fault generations. During the late-to middle Miocene, the west-dipping Cerro Prieto and San Felipe faults formed a domino array. Then, during the Pleistocene the Consag and Wagner faults dissected the hanging-wall of the Cerro Prieto fault forming the modern Wagner basin. Thermal modeling of the deep borehole temperatures suggests that the heat flow in these basins in the order of 110 mW/m2 which is in agreement with superficial heat flow measurements in the northern Gulf of California Rift System.

Benthic flux of nutrients and trace metals in the northern component of San Francisco Bay, California

Science.gov (United States)

Kuwabara, James S.; Topping, Brent R.; Parcheso, Francis; Engelstad, Anita C.; Greene, Valerie E.

2009-01-01

Two sets of sampling trips were coordinated in late summer 2008 (weeks of July 8 and August 6) to sample the interstitial and overlying bottom waters at 10 shallow locations (9 sites meters in depth) within the northern component of the San Francisco Bay/Delta (herein referred to as North Bay). The work was performed to better understand sources of biologically reactive solutes (namely, dissolved macronutrients and trace metals) that may affect the base of the food web in this part of the estuary. A nonmetallic pore-water profiler was used to obtain the first centimeter-scale estimates of the vertical solute-concentration gradients for diffusive-flux determinations. This study, performed in collaboration with scientists from San Francisco State University?s Romberg Tiburon Center for Environmental Studies, provides information to assist in developing and refining management strategies for the Bay/Delta system and supports efforts to monitor changes in food-web structure associated with regional habitat modifications directed by the California Bay-Delta Authority. On July 7, 2008, and August 5, 2008, pore-water profilers were successfully deployed at six North Bay sites per trip to measure the concentration gradient of dissolved macronutrients and trace metals near the sediment-water interface. Only two of the sites (433 and SSB009 within Honker Bay) were sampled in both series of profiler deployments. At each sampling site, profilers were deployed in triplicate, while discrete samples and dataloggers were used to collect ancillary data from both the water column and benthos to help interpret diffusive-flux measurements. Benthic flux of dissolved (0.2-micron filtered) inorganic phosphate (that is, soluble reactive phosphorus (SRP)) ranged from negligible levels (-0.003?0.005 millimole per square meter per day (mmole m-2d-1) at Site 4.1 outside Honker Bay) to 0.060?0.006 mmole m-2d-1 near the northern coast of Brown?s Island. Except for the elevated flux at Browns

Air-sea exchange of CO2 in the Gulf of Kutch, northern Arabian Sea based on bomb-carbon in corals and tree rings

International Nuclear Information System (INIS)

Chakraborty, S.; Ramesh, R.; Krishnaswami, S.

1994-01-01

Radiocarbon analyses were carried out in the annual bands of a 40 year old coral collected from the Gulf of Kutch (22.6degN, 70degE) in the northern Arabian Sea and in the annual rings of a teak tree from Thane (19deg14'N, 73deg24'E) near Bombay. These measurements were made in order to obtain the rates of air-sea exchange of CO 2 and the advective mixing of water in the Gulf of Kutch. The Δ 14 C peak in the Thane tree occurs in the year 1964, with a value of ∼630 part per thousand, significantly lower than that of the mean atmospheric Δ 14 C of the northern hemisphere (∼1000 part per thousand). The radiocarbon time series of the coral was modelled considering the supply of carbon and radiocarbon to the gulf through air-sea exchange and advective water transport from the open Arabian Sea. A reasonable fit for the coral data was obtained with an air-sea CO 2 exchange rate of 11-12 mol m -2 yr -1 , and an advective velocity of 28 m yr -1 between the Arabian Sea and the Gulf of Kutch; this was based on a model generated time series for radiocarbon in the Arabian Sea. The deduced velocity (∼ 28 m yr -1 ) of the advective transport of water between the Gulf and the Arabian Sea is much lower than the surface tidal current velocity in this region, but can be understood in terms of net fluxes of carbon and radiocarbon to the gulf to match the observed coral Δ 14 C time series. (author). 30 refs., 7 figs., 2 tabs

Seasonal variability in the surface sediments of Mobile Bay, Alabama, recorded by geochemistry and foraminifera, 2009–2010

Science.gov (United States)

Umberger, D.K.; Osterman, L.E.; Smith, C.G.; Frazier, J.; Richwine, K.A.

2012-01-01

A study was undertaken in order to document and quantify recent environmental change in Mobile Bay, Alabama. The study was part of the Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazard Susceptibility project, a regional project funded by the Coastal and Marine Geology Program to understand how natural forcings and anthropogenic modifications influence coastal ecosystems and their susceptibility to coastal hazards. Mobile Bay is a large drowned-river estuary that has been modified significantly by humans to accommodate the Port of Mobile. Examples include repeated dredging of a large shipping channel down the central axis of the bay and construction of a causeway across the head of the bay and at the foot of the bayhead delta. In addition to modifications, the bay is also known to have episodic periods of low oxygen (hypoxia) that result in significant mortality to fish and benthic organisms (May, 1973). For this study a series of surface sediment samples were collected. Surface benthic foraminiferal and bulk geochemical data provide the modern baseline conditions of the bay and can be used as a reference to changing environmental parameters in the past (Osterman and Smith, in press) and into the future. This report archives data collected as part of the Mobile Bay Study that may be used in future environmental change studies.

2010 Northern San Francisco Bay Area Lidar: Portions of Alameda, Contra Costa, Marin, Napa, San Francisco, Solano, and Sonoma Counties

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This Light Detection and Ranging (LiDAR) dataset is a survey of northern San Francisco Bay, California. The project area consists of approximately 437 square miles...

State of oil pollution in the northern Arabian Sea after the 1991 Gulf oil spill

Digital Repository Service at National Institute of Oceanography (India)

Sengupta, R.; Fondekar, S.P.; Alagarsamy, R.

stream_size 30182 stream_content_type text/plain stream_name Mar_Pollut_Bull_27_85.pdf.txt stream_source_info Mar_Pollut_Bull_27_85.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 Marine Pollution... Bulletin, Volume 27, pp. 85-91, 1993. 0025-326X/93 $6.00+0.00 Printed in Great Britain. O 1993 Pergamon Press Ltd State of Oil Pollution in the Northern Arabian Sea after the 1991 Gulf Oil Spill R. SEN GUPTA, S. P. FONDEKAR and R. ALAGARSAMY National...

GULF OF MEXICO AQUATIC MORTALITY NETWORK (GMNET)

Science.gov (United States)

Five U.S. states share the northern coast of the Gulf, and each has a program to monitor mortalities of aquatic organisms (fish, shellfish, birds). However, each state has different standards, procedures, and documentation of mortality events. The Gulf of Mexico Aquatic Mortality...

GoMRC Website ‘Meta-analysis Report: Land-use and submerged aquatic vegetation change in the Gulf of Mexico’

Energy Technology Data Exchange (ETDEWEB)

Judd, Chaeli; Stefansson, Emily S.; Brushnahan, Heather

2007-12-06

Over the past century, health and spatial extent of seagrasses has decreased dramatically in the Gulf of Mexico. While some of the changes can be explained by direct impacts to the seagrass beds, we hypothesize that changes in the land use in the watersheds can also be correlated with the decline of seagrasses. Through this meta-analysis, we researched historical and compared trends in seagrass populations and land use in five bays and their watersheds within the Gulf of Mexico: Mobile Bay, Perdido Bay, Tampa Bay, Charlotte Harbor, and Galveston Bay. Using both historical records and spatial datasets, we examined land use and seagrass trends in these five areas.

The areal extent of brown shrimp habitat suitability in Mobile Bay, Alabama, USA: Targeting vegetated habitat restoration

Science.gov (United States)

Smith, L.M.; Nestlerode, J.A.; Harwell, L.C.; Bourgeois, P.

2010-01-01

The availability of wetlands and shallow water habitats significantly influences Gulf of Mexico (GOM) penaeid shrimp fishery productivity. However, the GOM region has the highest rate of wetland loss in the USA. Protection and management of these vital GOM habitats are critical to sustainable shrimp fisheries. Brown shrimp (Farfantepenaeus aztecus) are a major component of GOM fisheries. We present an approach for estimating the areal extent of suitable habitat for post-larval and juvenile brown shrimp in Mobile Bay, Alabama, using an existing habitat suitability index model for the northern GOM calculated from probabilistic survey of water quality and sediment data, land cover data, and submerged aquatic vegetation coverages. This estuarine scale approach is intended to support targeted protection and restoration of these habitats. These analyses indicate that approximately 60% of the area of Mobile Bay is categorized as suitable to near optimal for post-larval and juvenile shrimp and 38% of the area is marginally to minimally suitable. We identify potential units within Mobile Bay for targeted restoration to improve habitat suitability. ?? 2010 Springer Science+Business Media B.V.

Metals content in surface waters of an upwelling system of the northern Humboldt Current (Mejillones Bay, Chile)

Science.gov (United States)

Valdés, Jorge; Román, Domingo; Alvarez, Gabriel; Ortlieb, Luc; Guiñez, Marcos

Physical-chemical parameters (temperature, salinity, dissolved oxygen, nutrients, and chlorophyll concentration) of surface waters were used to evaluate the influence of biological and physical processes over the metal concentrations (Cd, Ni, V, Mo, Mn, and Fe) in different periods of a normal annual cycle (June 2002 and April 2003), in Mejillones Bay (23° S), one of northern Chile's strongest upwelling cells. Two points were sampled every 2 months, but statistical analysis of these parameters did not show any spatial differences in surface water composition (annual average) in this bay. The order of total and dissolved metals by abundance (annual mean) in the Mejillones Bay surface waters during the sampling period was Cd Oxygen Minimum Zone which characterizes the Mejillones bay should have an important influence on surface distribution of trace metals and can explain the high temporal variability observed in most of the metals analyzed in this work. A two-box conceptual model is proposed to suggest possible influences on metals in surface waters of this coastal ecosystem.

Skin Transcriptomes of common bottlenose dolphins (Tursiops truncatus) from the northern Gulf of Mexico and southeastern U.S. Atlantic coasts.

Science.gov (United States)

Neely, Marion G; Morey, Jeanine S; Anderson, Paul; Balmer, Brian C; Ylitalo, Gina M; Zolman, Eric S; Speakman, Todd R; Sinclair, Carrie; Bachman, Melannie J; Huncik, Kevin; Kucklick, John; Rosel, Patricia E; Mullin, Keith D; Rowles, Teri K; Schwacke, Lori H; Van Dolah, Frances M

2018-04-01

Common bottlenose dolphins serve as sentinels for the health of their coastal environments as they are susceptible to health impacts from anthropogenic inputs through both direct exposure and food web magnification. Remote biopsy samples have been widely used to reveal contaminant burdens in free-ranging bottlenose dolphins, but do not address the health consequences of this exposure. To gain insight into whether remote biopsies can also identify health impacts associated with contaminant burdens, we employed RNA sequencing (RNA-seq) to interrogate the transcriptomes of remote skin biopsies from 116 bottlenose dolphins from the northern Gulf of Mexico and southeastern U.S. Atlantic coasts. Gene expression was analyzed using principal component analysis, differential expression testing, and gene co-expression networks, and the results correlated to season, location, and contaminant burden. Season had a significant impact, with over 60% of genes differentially expressed between spring/summer and winter months. Geographic location exhibited lesser effects on the transcriptome, with 23.5% of genes differentially expressed between the northern Gulf of Mexico and the southeastern U.S. Atlantic locations. Despite a large overlap between the seasonal and geographical gene sets, the pathways altered in the observed gene expression profiles were somewhat distinct. Co-regulated gene modules and differential expression analysis both identified epidermal development and cellular architecture pathways to be expressed at lower levels in animals from the northern Gulf of Mexico. Although contaminant burdens measured were not significantly different between regions, some correlation with contaminant loads in individuals was observed among co-expressed gene modules, but these did not include classical detoxification pathways. Instead, this study identified other, possibly downstream pathways, including those involved in cellular architecture, immune response, and oxidative stress

Natural sunlight shapes crude oil-degradingbacterial communities in northern Gulf of Mexico surface waters

Directory of Open Access Journals (Sweden)

Hernando P Bacosa

2015-12-01

Full Text Available Following the Deepwater Horizon (DWH spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH site with amendments of crude oil, Corexit dispersant, or both for 36 d under natural sunlight in the northern Gulf of Mexico. The bacterial community was analyzed over time for total abundance, density of alkane and polycyclic aromatic hydrocarbon degraders, and community composition via pyrosequencing. Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure. In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas. Dark samples with oil were represented by members of Thalassobius, Winogradskyella, Alcanivorax, Formosa, Pseudomonas, Eubacterium, Erythrobacter, Natronocella, and Coxiella. Both oil and Corexit inhibited the Candidatus Pelagibacter with or without sunlight exposure. For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit. Overall, our findings improve understanding of oil pollution in surface water, and provide unequivocal evidence that sunlight is a key factor in determining bacterial community composition and dynamics in oil polluted marine waters.

Statewide summary for Mississippi: Chapter H in Emergent wetlands status and trends in the northern Gulf of Mexico: 1950-2010

Science.gov (United States)

Handley, Larry; Spear, Kathryn A.; Leggett, Ali; Thatcher, Cindy A.

2012-01-01

The Mississippi coastline is 113 linear kilometers (70 miles) long and its estuaries cover approximately 594 km (369 mi; Figure 1) (Handley and others, 2007). It has a man-made sand beach 43.5 km (27 mi) long and 595.5 km (370 mi) of shoreline (Klein and others, b., 1998). The Mississippi Sound extends across the coastal waters of the State and encompasses 175,412 ha (433,443 acres). It is bordered by the Mississippi coast; Mobile Bay, Ala.; the Gulf Islands National Seashore barrier islands; and Lake Borgne, La. The watersheds and drainages feeding into Mississippi Sound, excluding tidal exchange from the Gulf of Mexico, include Lake Borgne, Pearl River, Jourdan River, Wolf River, Biloxi River, Tchoutacabouffa River, Pascagoula River, and Mobile Bay. The Pascagoula River is one of the last undammed rivers in the continental U.S. and the only undammed river flowing into the Gulf of Mexico. Freshwater inflow into Mississippi Sound, excluding that from Mobile Bay, averages 882.4 m3 per second (30,806 ft3 per second). The Mississippi coastal zone contains approximately one-third of the State’s 120 ecological communities (Klein and others, a., 1998). Regional land use includes silviculture, agriculture, and urban development, including several coastal casinos. Commercial shipping, shipbuilding, phosphate rock refinement, and electric power generation companies include some of the industrial complexes found along the Mississippi coast. The three counties found along the Mississippi coast, Hancock, Harrison, and Jackson Counties, had a total population of 370,702 as of 2010, constituting 12.5 percent of the State’s population (U.S. Census Bureau, 2010). These counties cover over 160.9 km (100 mi) of coastline and are one of the fastest growing regions in the state (Klein and others, b., 1998).The casino industry, military installations, trade, and manufacturing provide most jobs in coastal Mississippi. Two major deep-water ports exist in coastal Mississippi

Understanding Nuisance Flooding Conceptualizations and Concerns of Stakeholders in the Northern U.S. Gulf Coast

Science.gov (United States)

DeLorme, D.; Collini, R.; Stephens, S. H.

2017-12-01

As sea level rises, nuisance flooding along coasts is increasing. There is a need to understand how the public views flooding events in order to tailor communications to different audiences appropriately and help improve community resilience. This interdisciplinary presentation is intended to foster greater awareness about present-day nuisance flooding, ongoing conversation about best practices for accurately and effectively communicating about this "cumulative hazard" and its risks, and consideration about possible preparation and mitigation options for community resilience. The presentation will begin by defining and explaining nuisance flooding according to scientific experts and the scholarly literature. Next, we will share several specific examples of how nuisance flooding is increasingly impacting certain areas in the Northern U.S. Gulf Coast to demonstrate the importance of raising attention to and better understanding of this phenomenon across a range of audiences. We will particularly focus on the complex interrelated social, economic, and ecological issues associated with this hazard. Then, we will compare and contrast conceptualizations of nuisance flooding (characteristics, causes, consequences) and associated concerns from the viewpoints and experiences of various stakeholders in the Northern U.S. Gulf Coast (e.g., natural resource managers, community planners, extension specialists). These data are synthesized from multiple research methods and engagement mechanisms (e.g., focus groups, workshop mapping exercises) implemented during the first year of a multi-year NOAA-sponsored interdisciplinary project on Dynamic Sea Level Rise Assessments of the Ability of Natural and Nature-based Features to Mitigate Surge and Nuisance Flooding. To conclude, we will provide future research recommendations along with references and resources about nuisance flooding.

Baseline concentration of ²¹⁰Po and ²¹⁰Pb in Sargassum from the northern Gulf.

Science.gov (United States)

Uddin, S; Aba, A; Bebhehani, M

2015-01-15

This baseline study highlights the (210)Po and (210)Pb concentration in two species of the benthic macroalgae Sargassum from northern Gulf, also known as the ROPME Sea Area (RSA). Within the marine environment, (210)Po is initially absorbed from water and concentrated by phytoplankton and macroalgae, and this concentrated (210)Po can then readily be passed along to the higher trophic level of the marine food web. The (210)Po concentration measured in Sargassum boveanum (22.5-25.6 Bq kg(-1)) was higher than that in Sargassum oligocystum (20.2-22.5 Bq kg(-1)), but is not statistically significant (p>0.064), where as the difference between (210)Pb concentrations in Sargassum boveanum (15.3-16.8 Bq kg(-1)) and Sargassum oligocystum (18.4-22.0 Bq kg(-1)) was statistically significant (p>0.019). The measured concentration factor for (210)Po in Sargassum in the northern Gulf varied between 0.55 and 1.2×10(4), values higher to the IAEA recommended value of 1×10(3). The (210)Po enrichment is observed in both the species of Sargassum,(210)Po/(210)Pb ratio was >1 at all the stations for all the samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

EVALUATION OF TROPHIC STATUS OF AGRAKHAN BAY (THE NORTH CASPIAN SEA AS A PART OF ECOLOGICAL MONITORING OF SPECIALLY PROTECTED AREAS

Directory of Open Access Journals (Sweden)

A. A. Gadzhiev

2013-01-01

Full Text Available Abstract. Aim. Hydrochemical composition of waters of Agrakhan Bay (the North Caspian Sea, degree of pollution, structure and quantitative characteristics of phytoplankton, zooplankton and zoobenthos is given in the paper. Evaluation of a trophic status of the bay and seasonal trophodynamics are given as a result of study.Material and methods. The study is based on original materials from expeditions of 2012 (Autumn and 2013 (Spring and Summer in Agrakhan Bay. The complex materials are collected on stations with distance 3.5 km. Totally was made 16 marine stations, where samples of water, phytoplankton, zooplankton and benthos were taken.Results. Agrakhan Bay is eutrophic by level of dissolved oxygen and its BOD. However, the oxygen deficiency is not observed. concentration of oxygen is high almost in all seasons, that has a beneficial effect on hydrobionts. Seasonal dynamics indicates that Agrakhansky bay is oligotrophic within a year, but its trophic status increases to mesotrophic and even to hypertrophic in some periods. The northern part ща the bay is eutrophic. Difference in trophic levels of different parts of the bay is the result of significant differences in depth and area of water surface.Conclusions. Anthropogenic impact on Agrakhan Bay increases its trophic status. Seasonal trophic level of Agrakhan Gulf except natural processes depends on the "purity" of the Terek River sediments, which are the main source of biogenic elements. Typically, the absolute concentration of biogenic elements in Agrakhan Bay increases with the increase of eutrophication.

First occurrence of the Indo-Pacific polychaete species Glycinde bonhourei Gravier, 1904 in the Hellenic seas (Northern Evvoikos Gulf

Directory of Open Access Journals (Sweden)

N. SIMBOURA

2008-05-01

Full Text Available A specimen of Glycinde bonhourei Gravier, 1904, an Indo-Pacific species, was found at a station near the metalliferous waste disposal in the Northern Evvoikos Gulf (Aegean Sea, eastern Mediterranean. This is the second report of this species in the Mediterranean Sea after its first finding in the Levantine basin (Israel and Egypt. This paper provides new information on its distributional range in the Mediterranean Sea.

Enhanced land subsidence in Galveston Bay, Texas: Interaction between sediment accumulation rates and relative sea level rise

Science.gov (United States)

Al Mukaimi, Mohammad E.; Dellapenna, Timothy M.; Williams, Joshua R.

2018-07-01

Galveston Bay is the second largest estuary along the northern Gulf of Mexico coast, with a watershed containing one of largest concentrations of petroleum and chemical industries globally, as well as Houston, the fifth largest metropolitan area in the USA. Throughout the last century, extensive groundwater extraction to support these industries and an expanding population has resulted in significantly enhanced land subsidence (0.6-3.0 cm yr-1). The highest subsidence rates observed in the bay are within the lower 15 km of the San Jacinto River/Houston Ship Channel region (SJR/HSC), with distal areas in East and West Galveston Bays having subsidence rates on the order of 0.2 cm yr-1. In order to investigate the impacts of subsidence on sedimentation, a series of 22 vibracores were collected throughout the bay, and 210Pb and 137Cs radioisotope geochronologies and grain size distributions were determined. Sediment accumulation rates are highest (1.9 ± 0.5 cm yr-1) in the SJR/HSC, and decrease (sedimentation rates are significantly (p sedimentation rates are lower (as much as 50%) than estimated RSLR, indicating a sediment accretionary deficit. In areas (e.g., Scott Bay) within the SJR/HSC, the bay has deepened by more than 1.5 m, suggesting that sediment accumulation cannot keep pace with RSLR. Ultimately, this has resulted in a loss of coastal wetlands and a conversion of marine habitats from relatively shallow to deeper water settings.

Statistical properties of the surface velocity field in the northern Gulf of Mexico sampled by GLAD drifters

OpenAIRE

Mariano, A.J.; Ryan, E.H.; Huntley, H.S.; Laurindo, L.C.; Coelho, E.; Ozgokmen, TM; Berta, M.; Bogucki, D; Chen, S.S.; Curcic, M.; Drouin, K.L.; Gough, M; Haus, BK; Haza, A.C.; Hogan, P

2016-01-01

The Grand LAgrangian Deployment (GLAD) used multiscale sampling and GPS technology to observe time series of drifter positions with initial drifter separation of O(100 m) to O(10 km), and nominal 5 min sampling, during the summer and fall of 2012 in the northern Gulf of Mexico. Histograms of the velocity field and its statistical parameters are non-Gaussian; most are multimodal. The dominant periods for the surface velocity field are 1–2 days due to inertial oscillations, tides, and the sea b...

Total petroleum hydrocarbons in edible marine biota from Northern Persian Gulf.

Science.gov (United States)

Nozar, Seyedeh Laili Mohebbi; Pauzi, Mohamad Zakaria; Salarpouri, Ali; Daghooghi, Behnam; Salimizadeh, Maryam

2015-04-01

To provide a baseline information for consumer's health, distribution of total petroleum hydrocarbons in 18 edible marine biota species from northern Persian Gulf was evaluated. The samples were purchased from fish market of Hormozgan Province, South of Iran. Marine biota samples included different species with various feeding habits and were analyzed based on ultraviolet florescence spectroscopy. Petroleum hydrocarbons showed narrow variation, ranging from 0.67 to 3.36 μg/g dry weight. The maximum value was observed in silver pomfret. Anchovy and silver pomfret with the highest content of petroleum hydrocarbons were known as good indicator for oil pollution in the studied area. From public health point of view, the detected concentrations for total petroleum hydrocarbons were lower than hazardous guidelines. The results were recorded as background data and information in the studied area; the continuous monitoring of pollutants is recommended, according to the rapid extension of industrial and oily activities in Hormozgan Province.

Near-surface stratigraphy and morphology, Mississippi Inner Shelf, northern Gulf of Mexico

Science.gov (United States)

Flocks, James G.; Kindinger, Jack; Kelso, Kyle W.; Bernier, Julie C.; DeWitt, Nancy T.; FitzHarris, Michael

2015-01-01

Over the past decade, the Mississippi Barrier Islands have been the focus of a comprehensive geologic investigation by the U.S. Geological Survey (USGS), in collaboration with the U.S. Army Corps of Engineers (USACE) and the National Park Service (NPS). The islands (Dauphin, Petite Bois, Horn, East Ship, West Ship, and Cat) are part of the Gulf Islands National Seashore (GUIS), and provide a diverse ecological habitat, protect the mainland from storm waves, and help maintain estuarine conditions within Mississippi Sound. Over the past century, the islands have been in a state of decline with respect to elevation and land-area loss. In 2005, the islands were severely impacted by Hurricane Katrina, which inundated them with a storm surge of 8 meters, causing severe shoreface erosion and widening breaches in Dauphin, West Ship, and Cat Islands. To evaluate the impact and fate of the islands, understanding their evolution and resiliency became a priority for the USGS under the Northern Gulf of Mexico Ecosystem Change and Hazard Susceptibility Project. The project formed the basis for collaboration with the USACE Mississippi Coastal Improvement Project, which is intended to restore portions of coastal Mississippi and GUIS affected by storm impact. Since then, many studies have contributed to our understanding of the islands’ morphology and nearshore stratigraphy. This report expands upon the nearshore component to provide a stratigraphic and morphologic assessment offshore of Petit Bois Island.

Natural Sunlight Shapes Crude Oil-Degrading Bacterial Communities in Northern Gulf of Mexico Surface Waters.

Science.gov (United States)

Bacosa, Hernando P; Liu, Zhanfei; Erdner, Deana L

2015-01-01

Following the Deepwater Horizon (DWH) spill in 2010, an enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico. Surface waters are characterized by intense sunlight and high temperature during summer. While the oil-degrading bacterial communities in the deep-sea plume have been widely investigated, the effect of natural sunlight on those in oil polluted surface waters remains unexplored to date. In this study, we incubated surface water from the DWH site with amendments of crude oil, Corexit dispersant, or both for 36 days under natural sunlight in the northern Gulf of Mexico. The bacterial community was analyzed over time for total abundance, density of alkane and polycyclic aromatic hydrocarbon degraders, and community composition via pyrosequencing. Our results showed that, for treatments with oil and/or Corexit, sunlight significantly reduced bacterial diversity and evenness and was a key driver of shifts in bacterial community structure. In samples containing oil or dispersant, sunlight greatly reduced abundance of the Cyanobacterium Synechococcus but increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Bartonella, and Halomonas. Dark samples with oil were represented by members of Thalassobius, Winogradskyella, Alcanivorax, Formosa, Pseudomonas, Eubacterium, Erythrobacter, Natronocella, and Coxiella. Both oil and Corexit inhibited the Candidatus Pelagibacter with or without sunlight exposure. For the first time, we demonstrated the effects of light in structuring microbial communities in water with oil and/or Corexit. Overall, our findings improve understanding of oil pollution in surface water, and provide unequivocal evidence that sunlight is a key factor in determining bacterial community composition and dynamics in oil polluted marine waters.

Overview of the Kinematics of the Salton Trough and Northern Gulf of California

Science.gov (United States)

Stock, J. M.

2016-12-01

In the Salton Trough and Northern Gulf of California, transtensional rifting is leading to full continental plate breakup, as a major continental block is being transferred to an oceanic plate. Since at least 6 Ma this region has taken up most of the plate boundary slip between the Pacific and North America plates at this latitude. We review the structural history of plate separation, as constrained by many recent studies of present and past fault configurations, seismicity, and basin development as seen from geology and geophysics. Modern activity in the USA is dominated by NW-striking strike-slip faults (San Andreas, San Jacinto, Elsinore), and subsidiary NE-striking faults. There is an equally broad zone in Mexico (faults from the Mexicali Valley to the Colorado River Delta and bounding the Laguna Salada basin), including active low-angle detachment faults. In both areas, shifts in fault activity are indicated by buried faults and exhumed or buried earlier basin strata. Seismicity defines 3 basin segments in the N Gulf: Consag-Wagner, Upper Delfin, and Lower Delfin, but localization is incomplete. These basins occupy a broad zone of modern deformation, lacking single transform faults, although major strike-slip faults formed in the surrounding continental area. The off-boundary deformation on the western side of the plate boundary has changed with time, as seen by Holocene and Quaternary faults controlling modern basins in the Gulf Extensional Province of NE Baja California, and stranded Pliocene continental and marine basin strata in subaerial fault blocks. The eastern side of the plate boundary, in the shallow northeastern Gulf, contains major NW-striking faults that may have dominated the earlier (latest Miocene-early Pliocene) kinematics. The Sonoran coastal plain likely buries additional older faults and basin sequences; further studies here are needed to refine models of the earlier structural development of this sector. Despite > 250 km of plate

Investigation of heavy metal pollutants at various depths in the Gulf of Izmit

International Nuclear Information System (INIS)

Ergül, Halim Aytekin; Varol, Tolga; Ay, Ümit

2013-01-01

Highlights: • Monitoring seasonal variations in heavy metal pollution. • Heavy metal levels according to depth in seawater from the Gulf of Izmit. • Industrial activity and biological life co-exist in Izmit Bay. -- Abstract: In this study, we report results concerning the accumulation of heavy metals in seawater from Izmit Bay. The bay was divided into the three parts: the eastern, the central and the western basins. The goal of this study was to determine levels of heavy metals at various depths in the bay between April 2008 and May 2010. Liquid–liquid extractions were performed on seawater samples. An atomic absorption spectrophotometer was used to measure levels of six metals: lead, cadmium, chromium, iron, manganese and zinc. We applied our results to evaluate the status of pollution in the Gulf of Izmit. Significant seasonal differences in metal concentrations and higher concentrations of many metals in water near the shore are evidence for uncontrolled release of pollutants in the water

Application of the coastal generalized ecosystem model (CGEM) to assess the impacts of a potential future climate scenario on northern Gulf of Mexico hypoxia

Science.gov (United States)

Mechanistic hypoxia models for the northern Gulf of Mexico are being used to guide policy goals for Mississippi River nutrient loading reductions. However, to date, these models have not examined the effects of both nutrient loads and future climate. Here, we simulate a future c...

The evolution of shallow crustal structures in early rift-transform interaction: a case study in the northern Gulf of California.

Science.gov (United States)

Farangitakis, Georgios-Pavlos; van Hunen, Jeroen; Kalnins, Lara M.; Persaud, Patricia; McCaffrey, Kenneth J. W.

2017-04-01

The Gulf of California represents a young oblique rift/transtensional plate boundary in which all of the transform faults are actively shearing the crust, separated by active rift segments. Previous workers have shown that in the northern Gulf of California, the relative plate motion between the Pacific and North American plates is distributed between: a) the Cerro Prieto Fault (CPF) in the NE b) the Ballenas Transform Fault (BTF) in the SW and c) a pull-apart structure located between these two faults consisting of a number of extensional basins (the Wagner, Consag, and Upper and Lower Delfin basins). A plate boundary relocation at approximately 2 Ma, continued to separate Isla Angel de la Guarda from the Baja California peninsula and created the 200x70 km2 NE-SW pull-apart structure located northeast of the BTF. Here we use seismic stratigraphy analysis of the UL9905 high resolution reflection seismic dataset acquired by the Lamont-Doherty Earth Observatory, Caltech, and the Centro de Investigación Científica y de Educación Superior de Ensenada to build on previous structural interpretations and seek to further understand the processes that formed the structural and sedimentary architecture of the pull-apart basin in the northern Gulf of California. We examine the formation of depositional and deformation structures in relation to the regional tectonics to provide insight into the development of structural patterns and related seismic-stratigraphic features in young rift-transform interactions. Using bathymetric data, characteristic seismic-stratigraphic packages, and seismic evidence of faulting, we confirm the existence of three major structural domains in the northern Gulf of California and examine the interaction of the seismic stratigraphy and tectonic processes in each zone. The first and most distinctive is an abrupt NE-SW 28x5 km2 depression on the seabed of the Lower Delfin Basin. This is aligned orthogonally to the BTF, is situated at its northern

Aliphatic and polycyclic aromatic hydrocarbons in Gulf of Trieste sediments (northern Adriatic): potential impacts of maritime traffic.

Science.gov (United States)

Bajt, Oliver

2014-09-01

The Gulf of Trieste (northern Adriatic) is one of the most urbanized and industrialized areas in the northern Adriatic, with intense maritime traffic experienced at multiple ports. The impact of maritime traffic on contamination by hydrocarbons in this area was assessed. Concentrations of hydrocarbons were higher near the expected contamination sources and still elevated in the adjacent offshore areas. Aliphatic hydrocarbons were mainly of petrogenic origin, with some contribution of biogenic origin. A continuous contamination by aliphatic hydrocarbons and degradation processes were hypothesized. Concentrations of total polycyclic aromatic hydrocarbons (PAH) were generally greater near the contamination sources. Compared to the prevailing pyrolytic origin, the petrogenic PAH origin seemed to be less important, but not negligible. Results revealed that intensive maritime traffic is a probable source of contamination by hydrocarbons in the investigated area, which is largely limited to areas near the contamination sources.

Status of macrobenthic community of Manifa-Tanajib Bay System of Saudi Arabia based on a once-off sampling event

KAUST Repository

Joydas, Thadickal Viswanathan; Krishnakumar, P. K.; Qurban, Mohammad Ali; Ali, Said M.; Al-Suwailem, Abdulaziz M.; Al-Abdulkader, Khaled

2011-01-01

Shallow water bays located in the western Arabian Gulf experience harsh environmental conditions. Some of these bays, including Manifa-Tanajib Bay System (MTBS), were also exposed to the 1991 oil pollution event. This study investigates the status

Systematic Lithologic Calibration of Neogene Mass-Transport Deposits Seismic Character in Mississippi Canyon of the Northern Gulf of Mexico, USA.

Science.gov (United States)

Gutierrez, M. A.; Snedden, J.

2017-12-01

Few publications have attempted detailed lithologic calibration of Mass Transport Deposits, usually as a byproduct of mud log descriptions. While the principal motivation for further understanding these slope failure deposits are driven by the economics of deep-water hydrocarbon exploration, the geohazard-related risks of storm-wave loading, and the shallow gas, also provide a driving concern for these deposits. Such risks can be mitigated and prevented by in depth analysis of slope stability and failure. The Mississippi Canyon of the Northern Gulf of Mexico is one of the few basins to contain enough available density of seismic and well data to provide a well-constrained lithologic characterization throughout a MTD-rich continental margin. The proposed hypothesis evaluates: 1) the differences between attached and detached MTDs in the Neogene Northern Gulf of Mexico through seismic characterization and well log analysis, 2) variations of MTD dimensions and map geometries in relation to depositional age throughout the northeastern and northcentral Gulf of Mexico, and 3) the differentiation between sand-prone and shale-prone MTD's in relation to associated depositional mechanisms. This study will attempt lithologic calibration of MTDs in Pleistocene -Miocene strata of the study area through integration of seismic observations (focused in supra-salt basins, which have the highest seismic data quality) and lithologic related information extracted from logs, mud logs (cuttings), and available core data to further constrain the distribution of MTD types, lithology, and geometries. Initial interpretations reflect a variance of seismic character responses to the presence of sandstone and shale (constrained by wells) throughout different regions and salt tectonic domains of the MTD geobodies. Further analysis will relate different seismic facies throughout MTDs to improve the understanding of seismic character and related lithologic facies throughout the deposits, in

Barataria Bay 2005-2006

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Nekton on the northern Gulf of Mexico depend on estuarine nursery areas, but patterns of habitat use and the underlying processes that drive these patterns are not...

Modeling of the Foca-Uzunada magnetic anomaly and thermal structure in the gulf of Izmir, western Turkey

Science.gov (United States)

Aydemir, Attila; Bilim, Funda; Cifci, Gunay; Okay, Seda

2018-05-01

The Gulf of Izmir (GoI) is one of the largest gulfs in the Aegean Sea, Turkey. There is a large magnetic anomaly extending in the NE-SW direction between Foca and Uzunada (Uzun Island) in the gulf. Previously, Curie Point Depth (CPD), geothermal gradient, heat-flow and radiogenic heat production maps of the onshore part of the Aegean region were constructed from the aeromagnetic data. In this study, the same maps except radiogenic heat production map are presented for the offshore part and the largest magnetic anomaly in the northern part of the gulf is focused, particularly. As a result, the thermal structure of GoI is clearly defined and according to the results of this study, CPD values were found from 7 km in the NE of Foca to 10 km through the south of the gulf. The geothermal gradient values vary between 50 and 80 °C/km. Maximum heat flow values around the anomaly are calculated as 200 and 215 mW/m2 according to the thermal conductivity coefficients of 2.5 W m-1 K-1 and 2.7 W m-1 K-1, respectively. Although the anomaly is located in the Izmir Gulf; CPD, geothermic gradient, heat flow anomalies are shifted through the north of Foca and Aliaga towns in the Candarli Bay. This prominent anomaly in the Gulf of Izmir is associated with the magmatics that were encountered at 969 m in the Foca-1 well although it was drilled about 2 km away from the outermost closed contour of the magnetic anomaly. The anomaly is also modeled three dimensionally (3D) in this study. In the model map, the top of the causative body is completely located in the outer part of the gulf, and is very shallow at about 0.5 km while its bottom is inclined through the west of Cigli and Menemen. From this viewpoint, it is possible to suggest that the causative body is inclined through the Foca Peninsula. However, its closed contours are in the NE direction, through the Candarli Bay. Top depth of the causative body is also calculated from the basement horizon on the seismic sections crossing this

River capture and sediment redistribution in northern Tunisia: The doom of Utica

Science.gov (United States)

Booth-Rea, Guillermo; Camafort, Miquel; Pérez-Peña, J. Vicente; Melki, Fetheddine; Ranero, César; Azañón, José Miguel; Gracia, Eulalia; Ouadday, Mohamed

2016-04-01

Utica was a flourishing port city in northern Tunisia since the Phoenician times, 12-9th century B.C., until the 4th century A.D.. However, at present it is located 10 km from the coastline after very fast late Holocene progradation of the Mejerda River delta into the bay of Utica. This fast delta progradation occurred after Mejerda River captured Tine River increasing 140 % the river catchment area. Charcoal fragments present in the youngest Tine river terrace at the wind gap give a conventional radiocarbon age of 3240 +/- 30yr BP, indicating that the capture occurred after this date. Quaternary fluvial terraces located in the Tine River paleovalley have been folded and uplifted above a fold related to the active El Alia Tebousouk reverse fault (ETF). Continued uplift of the Tine River valley above the ETF favoured headward erosion of the Medjerda river tributaries creating a transverse drainage that captured Tine River. This capture produced an important change in sediment discharge along the northern Tunisia coast driving sediments to the Gulf of Tunis instead of feeding the Tyrrhenian Sea through the Ichkeul and Bizerte lakes. Although anthropogenic derived degradation of northern Tunisia land for agricultural purposes probably influenced the increase in sediment into the Utica bay, the main cause of rapid progradation of the Medjerda River delta during the late Holocene is related to its increase in drainage area after capturing the Tine River. This process was mostly driven by local contractive tectonics linked to the seismogenic Alia Tebousouk reverse fault.

Identification of largemouth bass virus in the introduced Northern Snakehead inhabiting the Chesapeake Bay watershed.

Science.gov (United States)

Iwanowicz, L; Densmore, C; Hahn, C; McAllister, P; Odenkirk, J

2013-09-01

The Northern Snakehead Channa argus is an introduced species that now inhabits the Chesapeake Bay. During a preliminary survey for introduced pathogens possibly harbored by these fish in Virginia waters, a filterable agent was isolated from five specimens that produced cytopathic effects in BF-2 cells. Based on PCR amplification and partial sequencing of the major capsid protein (MCP), DNA polymerase (DNApol), and DNA methyltransferase (Mtase) genes, the isolates were identified as Largemouth Bass virus (LMBV). Nucleotide sequences of the MCP (492 bp) and DNApol (419 pb) genes were 100% identical to those of LMBV. The nucleotide sequence of the Mtase (206 bp) gene was 99.5% identical to that of LMBV, and the single nucleotide substitution did not lead to a predicted amino acid coding change. This is the first report of LMBV from the Northern Snakehead, and provides evidence that noncentrarchid fishes may be susceptible to this virus.

Identification of largemouth bass virus in the introduced Northern snakehead inhabiting the Cheasapeake Bay watershed

Science.gov (United States)

Iwanowicz, Luke R.; Densmore, Christine L.; Hahn, Cassidy M.; McAllister, Phillip; Odenkirk, John

2013-01-01

The Northern Snakehead Channa argus is an introduced species that now inhabits the Chesapeake Bay. During a preliminary survey for introduced pathogens possibly harbored by these fish in Virginia waters, a filterable agent was isolated from five specimens that produced cytopathic effects in BF-2 cells. Based on PCR amplification and partial sequencing of the major capsid protein (MCP), DNA polymerase (DNApol), and DNA methyltransferase (Mtase) genes, the isolates were identified as Largemouth Bass virus (LMBV). Nucleotide sequences of the MCP (492 bp) and DNApol (419 pb) genes were 100% identical to those of LMBV. The nucleotide sequence of the Mtase (206 bp) gene was 99.5% identical to that of LMBV, and the single nucleotide substitution did not lead to a predicted amino acid coding change. This is the first report of LMBV from the Northern Snakehead, and provides evidence that noncentrarchid fishes may be susceptible to this virus.

A recent perspective of the Circulation in the Gulf of Mexico

Science.gov (United States)

Candela, J.; Ochoa-de-La-Torre, J. L.; Sheinbaum, J.; Perez-Brunius, P.; Pallas-Sanz, E.; Kolodziejczyk, N.

2013-05-01

The flow through the Gulf of Mexico is an integral part of the North Atlantic Ocean Subtropical Gyre Circulation, known to be forced by the wind over the North Atlantic and by an equivalent contribution from the inter-hemispheric Meridional Overturning Cell. To the North Atlantic Circulation, the Gulf represents an important energy and vorticity sink through the particular behavior of the Loop Current within. Comprehending the structure and dynamics of the Loop Current System (which includes the Yucatan Current (YC), Loop Current (LC), the shedding of anticyclonic Loop Current Eddies (LCE) and peripheral cyclonic gyres) is fundamental for understanding the circulation in the entire Gulf. Within the Gulf, the eastern Loop Current and the western Campeche Bay (CB) regions are characterized by persistent eddy structures, with less structured eddy fields in between. Of these later ones, the northwestern Gulf is a geostrophic turbulence area, constantly perturbed by LCE, which represents, at the same time, an important dissipation and circulation forcing region for the Western Gulf. Important processes recently investigated that will be discussed: 1) The generation and maintenance of the Geostrophic Turbulence field in the north western Gulf. 2) The circulation in deep water induced by the surface geostrophic turbulence field. 3) The generation of intensive jets at depth by interaction of +/- gyres. 4) The generation of coastal trap waves by the interaction of LCEs with the western shelf. 5) The generation of deep topographic Roosby waves by topographic interactions of the LCEs with topography. 5) The characteristics of the Bay of Campeche Circulation, The Campeche Gyre and its interaction with LCEs. 6) The Gulf's response to the passage of hurricanes. 7) The trapping of inertial waves by the LCEs and the related enhanced mixing.

Conservation Status of the Indo-Pacific Humpback Dolphin (Sousa chinensis) in the Northern Beibu Gulf, China.

Science.gov (United States)

Chen, Bingyao; Xu, Xinrong; Jefferson, Thomas A; Olson, Paula A; Qin, Qiurong; Zhang, Hongke; He, Liwen; Yang, Guang

2016-01-01

There has been very little previous research on Indo-Pacific humpback dolphins (Sousa chinensis) in the Beibu Gulf of southern China. Here, we report on the population size, habitat and ecology, threats, and overall conservation status of this putative population. 'Population size' was estimated based on photo-identification mark/recapture analysis. It was estimated to number a total of 398-444 individuals (95% CI: 393-506), with two apparently distinct groups in the Dafengjiang-Nanliujiang Estuary and at Shatian-Caotan. Movements of dolphins in the Beibu Gulf appear to be limited, with high site fidelity. These dolphins were found to occur mainly in shallow coastal waters near estuaries. The main threats are fisheries interactions (including by-catch), vessel traffic, mariculture operations, dolphin-watching tourism, and habitat degradation (including marine construction activities and large-scale land reclamation). Although the conservation status of this putative population has been considered to be better than that of other populations of the species in more northern areas of China, there is still reason for strong concern about its future, and several management recommendations are made. © 2016 Elsevier Ltd. All rights reserved.

Polycyclic Aromatic Hydrocarbons Identification and Source Discrimination in Rural Soil of the Northern Persian Gulf Coast

Directory of Open Access Journals (Sweden)

Fatemeh Valizadeh-kakhki

2014-01-01

Full Text Available Due to strategic situation of the Persian Gulf, identifying the petroleum pollution level and source is an important issue. Therefore, this paper enhanced fingerprinting method of applying biomarkers Polycyclic Aromatic Hydrocarbons (PAHs in identifying source and distribution of oil spills of the exposed areas. 10 soil samples collected from the northern coasts of the Persian Gulf along three provinces in the south of Iran. PAH concentrations in the soil ranged from 42.76 to 5596.49 ng.g-1. In the present study the distribution of 3 ringed PAHs was much higher than the other PAHs. Phenanthrene and alkylated derivatives of phenanthrene such as 3-methyl, 2-methyl, 9-methyl and 1-methyl phenanthrene were distinctively higher than the other components. According to the result PAHs concentration can be considered as no or little risk of toxicity for the organisms living in soil except for Fluoranthhene, comparing LD50. Applying marker ratios revealed that in most of the sampling sites showed perogenic sources and it emphasizes on the direct impact of oil and petroleum products to the lands due to oil well exploitation and transferring pipelines.

Watershed and Hydrodynamic Modeling for Evaluating the Impact of Land Use Change on Submerged Aquatic Vegetation and Seagrasses in Mobile Bay

Science.gov (United States)

Estes, Maurice G.; Al-Hamdan, Mohammed; Thom, Ron; Quattrochi, Dale; Woodruff, Dana; Judd, Chaeli; Ellism Jean; Watson, Brian; Rodriguez, Hugo; Johnson, Hoyt

2009-01-01

There is a continued need to understand how human activities along the northern Gulf of Mexico coast are impacting the natural ecosystems. The gulf coast is experiencing rapid population growth and associated land cover/land use change. Mobile Bay, AL is a designated pilot region of the Gulf of Mexico Alliance (GOMA) and is the focus area of many current NASA and NOAA studies, for example. This is a critical region, both ecologically and economically to the entire United States because it has the fourth largest freshwater inflow in the continental USA, is a vital nursery habitat for commercially and recreational important fisheries, and houses a working waterfront and port that is expanding. Watershed and hydrodynamic modeling has been performed for Mobile Bay to evaluate the impact of land use change in Mobile and Baldwin counties on the aquatic ecosystem. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for land use Scenarios in 1948, 1992, 2001, and 2030. The Prescott Spatial Growth Model was used to project the 2030 land use scenario based on observed trends. All land use scenarios were developed to a common land classification system developed by merging the 1992 and 2001 National Land Cover Data (NLCD). The LSPC model output provides changes in flow, temperature, sediments and general water quality for 22 discharge points into the Bay. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment concentrations on a grid with four vertical profiles throughout the Bay s aquatic ecosystems. The models were calibrated using in-situ data collected at sampling stations in and around Mobile bay. This phase of the project has focused on sediment modeling because of its significant influence on light attenuation which is a critical factor in the health of submerged aquatic

Structure and flow-induced variability of the subtidal salinity field in northern San Francisco Bay

Science.gov (United States)

Monismith, Stephen G.; Kimmerer, W.; Burau, J.R.; Stacey, M.T.

2002-01-01

The structure of the salinity field in northern San Francisco Bay and how it is affected by freshwater flow are discussed. Two datasets are examined: the first is 23 years of daily salinity data taken by the U.S. Bureau of Reclamation along the axis of northern San Francisco Bay: the second is a set of salinity transects taken by the U.S. Geological Survey between 1988 and 1993. Central to this paper is a measure of salinity intrusion. X2: the distance from the Golden Gate Bridge to where the bottom salinity is 2 psu. Using X2 to scale distance, the authors find that for most flow conditions, the mean salinity distribution of the estuary is nearly self-similar with a salinity gradient in the center 70% of the region between the Golden Gate and X2 that is proportional to X2-1. Analysis of covariability of Q and X2 showed a characteristics timescale of adjustment of the salinity field of approximately 2 weeks. The steady-state response deduced from the X2 time series implies that X2 is proportional to riverflow to the 1/7 power. This relation, which differs from the standard 1/3 power dependence that is derived theoretically assuming constant exchange coefficients, shows that the upstream salt flux associated with gravitational circulation is more sensitive to the longitudinal salinity gradient than theory supposes. This is attributed to the strengthening of stratification caused by the stronger longitudinal salinity gradient that accompanies larger river flows.

The Importance of Zostera marina to a Local Food Web Based on the Analysis of Compound Specific Isotopes in Maquoit Bay, Gulf of Maine

Science.gov (United States)

Doolittle, H. A.; Johnson, B. J.; Ambrose, W. G.; Locke, W.; Harris, C. M.

2010-12-01

Zostera marina (also known as eelgrass) is an important primary producer in near shore ecosystems in the Gulf of Maine, providing both habitat and nutrients for a variety of organisms (e.g., crustaceans, polychaetes, gastropods, and fish). The purpose of this study is to use compound specific δ13C analyses of essential amino acids to determine the degree to which organic matter derived from isotopically distinct primary producers (e.g., eelgrass, phytoplankton, and epiphytic algae) contribute to the diets of snails, shrimp, and fish in an eelgrass system in Casco Bay. Maquoit Bay, located in northwestern Casco Bay, in the Gulf of Maine, is a shallow estuarine system that is characterized by silt and clay sized sediments and the presence of extensive eelgrass beds. Amino acid concentrations and δ13C compositions were determined for a variety of sample-types collected in July-August, 2010, from three sites in the study area, including muscle tissue from Tautogolabrus adspersus (cunner), Gasterosteus aculeatus (3-spined stickleback), Nassarius obsoletus (snail), and Mysis spp. (shrimp), seston (i.e., phytoplankton), Z. marina, and epiphytic algae. TFAA amino acid derivatives of the total hydrolyzate were analyzed by GC-FID for amino acid concentration, and by GC-c-IRMS- for carbon isotope composition. Muscle tissue was dominated by glutamic and aspartic acids, and leucine, whereas Zostera marina was dominated by aspartic and glutamic acids, and proline. Phenylalanine and leucine in Z. marina are approximately 10 ‰ enriched in 13C relative to these same amino acids in the seston. The carbon isotope values of these essential amino acids are significantly more enriched in 13C for N. obsoletus than for T. adspersus, G. aculeatus, and Mysis spp. These data suggest that organic matter derived from Z. marina and/or epiphytic algae is more important in the diets of N. obsoletus, and organic matter derived from seston is more important for the diets of T. adspersus, G

Continental breakup by oblique extension: the Gulf of California

Science.gov (United States)

van Wijk, J.; Axen, G. J.

2017-12-01

We address two aspects of oblique extension: 1) the evolution of pull-apart basins, and how/when they may evolve into seafloor spreading segments; and 2) the formation of microcontinents. The Gulf of California formed by oblique extension. Breakup resulted in oceanic crust generation in the southern and central parts, while in the northern Gulf/Salton Trough a thick layer of (meta-)sediments overlies thinned continental crust. We propose a simple mechanism to explain this N-S variation. We assume that oblique rifting of the proto-Gulf province resulted in pull-apart basins, and use numerical models to show that such pull-apart basins do not develop into seafloor spreading segments when their length-to-width ratios are small, as is the case in the northern Gulf. In the central and southern Gulf the length-to-width ratios were larger, promoting continent rupture. The mechanisms behind this fate of pull-apart basins will be discussed in the presentation. In the southern Gulf, potential field models show that the Tamayo Bank in the southern Gulf is likely a microcontinent, separated from the main continent by the Tamayo trough. The thickness of the ocean crust in the Tamayo trough is anomalously small, suggesting that initial seafloor spreading was magma-starved and unsuccessful, causing the location of rifting and seafloor spreading to jump. As a consequence a sliver of continent broke off, forming the microcontinent. We suggest that worldwide this may be a common process for microcontinent formation.

Variation in abundance of Pacific Blue Mussel (Mytilus trossulus) in the Northern Gulf of Alaska, 2006-2015

Science.gov (United States)

Bodkin, James L.; Coletti, Heather A.; Ballachey, Brenda E.; Monson, Daniel H.; Esler, Daniel; Dean, Thomas A.

2018-01-01

Mussels are conspicuous and ecologically important components of nearshore marine communities around the globe. Pacific blue mussels (Mytilus trossulus) are common residents of intertidal habitats in protected waters of the North Pacific, serving as a conduit of primary production to a wide range of nearshore consumers including predatory invertebrates, sea ducks, shorebirds, sea otters, humans, and other terrestrial mammals. We monitored seven metrics of intertidal Pacific blue mussel abundance at five sites in each of three regions across the northern Gulf of Alaska: Katmai National Park and Preserve (Katmai) (2006-2015), Kenai Fjords National Park (Kenai Fjords) (2008-2015) and western Prince William Sound (WPWS) (2007-2015). Metrics included estimates of: % cover at two tide heights in randomly selected rocky intertidal habitat; and in selected mussel beds estimates of: the density of large mussels (≥ 20 mm); density of all mussels > 2 mm estimated from cores extracted from those mussel beds; bed size; and total abundance of large and all mussels, i.e. the product of density and bed size. We evaluated whether these measures of mussel abundance differed among sites or regions, whether mussel abundance varied over time, and whether temporal patterns in abundance were site specific, or synchronous at regional or Gulf-wide spatial scales. We found that, for all metrics, mussel abundance varied on a site-by-site basis. After accounting for site differences, we found similar temporal patterns in several measures of abundance (both % cover metrics, large mussel density, large mussel abundance, and mussel abundance estimated from cores), in which abundance was initially high, declined significantly over several years, and subsequently recovered. Averaged across all sites, we documented declines of 84% in large mussel abundance through 2013 with recovery to 41% of initial abundance by 2015. These findings suggest that factors operating across the northern Gulf of

Plate boundary deformation at the latitude of the Salton Trough - northern Gulf of California (Invited)

Science.gov (United States)

Stock, J. M.

2013-12-01

Along the Pacific-North America plate boundary zone, the segment including the southern San Andreas fault to Salton Trough and northern Gulf of California basins has been transtensional throughout its evolution, based on Pacific-North America displacement vectors calculated from the global plate circuit (900 × 20 km at N54°W since 20 Ma; 460 × 20 km at N48°W since 11 Ma). Nevertheless, active seismicity and focal mechanisms show a broad zone of plate boundary deformation within which the inferred stress regime varies locally (Yang & Hauksson 2013 GJI), and fault patterns in some regions suggest ongoing tectonic rotation. Similar behavior is inferred to have occurred in this zone over most of its history. Crustal structure in this region is constrained by surface geology, geophysical experiments (e.g., the 2011 Salton Seismic Imaging Project (SSIP), USGS Imperial Valley 1979, PACE), and interdisciplinary marine and onland studies in Mexico (e.g., NARS-Baja, Cortes, and surveys by PEMEX). Magnetic data (e.g., EMAG-2) aids in the recognition of large-scale crustal provinces and fault boundaries in regions lacking detailed geophysical surveys. Consideration of existing constraints on crustal thickness and architecture, and fault and basin evolution suggests that to reconcile geological deformation with plate motion history, the following additional factors need to be taken into account. 1) Plate boundary displacement via interacting systems of rotating blocks, coeval with slip on steep strike slip faults, and possibly related to slip on low angle extensional faults (e.g, Axen & Fletcher 1998 IGR) may be typical prior to the onset of seafloor spreading. This fault style may have accommodated up to 150 km of plate motion in the Mexican Continental Borderland and north of the Vizcaino Peninsula, likely between 12 and 15 Ma, as well as explaining younger rotations adjacent to the Gulf of California and current deformation southwest of the Salton Sea. 2) Geophysical

Storm-driven delivery of sediment to the continental slope: Numerical modeling for the northern Gulf of Mexico

Science.gov (United States)

Harris, C. K.; Kniskern, T. A.; Arango, H.

2016-02-01

The supply of sediment from the continental shelf to deeper waters is of critical importance for building continental margin repositories of sediment, and may also factor into episodic events on the continental slope such as turbidity currents and slope failures. While numerical sediment transport models have been developed for coastal and continental shelf areas, they have not often been used to infer sediment delivery to deeper waters. A three-dimensional coupled hydrodynamic - suspended sediment transport model for the northern Gulf of Mexico has been developed and run to evaluate the types of conditions that are associated with delivery of suspended sediment to the continental slope. Accounting for sediment delivery by riverine plumes and for sediment resuspension by energetic waves and currents, the sediment transport calculations were implemented within the Regional Ocean Modeling System (ROMS). The model domain represents the northern Gulf of Mexico shelf and slope including the Mississippi birdfoot delta and the Mississippi and DeSoto Canyons. To investigate the role of storms in driving down-slope sediment fluxes, model runs that encompassed fall, 2007 through late summer, 2008 the summer and fall of 2008 were analyzed. This time period included several winter storms, and the passage of two hurricanes (Ike and Gustav) over the study area. Preliminary results indicated that sediment delivery to the continental slope was triggered by the passage of these storm events, and focused at certain locations, such as submarine canyons. Additionally, a climatological analysis indicates that storm track influences both the wind-driven currents and wave energy on the shelf, and as such plays an important role in determining which storms trigger delivery of suspended continental shelf sediment to the adjacent slope.

Surveys of murre colony attendance in the northern Gulf of Alaska following the Exxon Valdez oil spill

International Nuclear Information System (INIS)

Erikson, D.E.

1995-01-01

Field surveys were conducted in July and August 1991 on 32 of the 36 murre (Uria spp.) colonies in the northern Gulf of Alaska to assess colony attendance (number of birds present at a colony) two years after the exxon Valdez oil spill. The surveys focused on murre colonies because murres represented 74% of the recovered seabird carcasses and because it had claimed that there was large-scale mortality of murres, leading to 60% to 70% decreases at some large colonies and population recovery periods of 20 to 70 years. Murres were present at all 32 colonies, and colony attendance estimates were generally similar to those from historical (prespill) surveys, particularly for those colonies in the direct path of the spill, i.e., the Barren Islands and Chiswell islands. Colony attendance levels in 1991 do not support the contention that murre colony attendance in the study area was drastically lower than historical levels. When colonies were grouped according to risk of oil exposure, the mean changes in attendance between 1991 and historical murre surveys did not differ significantly among the groups. Factors that could account for the observed similarity of 1991 and historical murre counts despite the high estimated mortality are (1) overestimation of mortality or (2) replacement of lost breeders through either recruitment of formerly nonbreeding individuals into the breeding population at spill-affected colonies or immigration of murres form nonaffected colonies. The findings of this study suggest that impacts of the Exxon Valdez oil spill on murre colony attendance in the northern Gulf of alaska were relatively short-term. 118 refs., 5 figs., 8 tabs

Mapping Surface Water DOC in the Northern Gulf of Mexico Using CDOM Absorption Coefficients and Remote Sensing Imagery

Science.gov (United States)

Kelly, B.; Chelsky, A.; Bulygina, E.; Roberts, B. J.

2017-12-01

Remote sensing techniques have become valuable tools to researchers, providing the capability to measure and visualize important parameters without the need for time or resource intensive sampling trips. Relationships between dissolved organic carbon (DOC), colored dissolved organic matter (CDOM) and spectral data have been used to remotely sense DOC concentrations in riverine systems, however, this approach has not been applied to the northern Gulf of Mexico (GoM) and needs to be tested to determine how accurate these relationships are in riverine-dominated shelf systems. In April, July, and October 2017 we sampled surface water from 80+ sites over an area of 100,000 km2 along the Louisiana-Texas shelf in the northern GoM. DOC concentrations were measured on filtered water samples using a Shimadzu TOC-VCSH analyzer using standard techniques. Additionally, DOC concentrations were estimated from CDOM absorption coefficients of filtered water samples on a UV-Vis spectrophotometer using a modification of the methods of Fichot and Benner (2011). These values were regressed against Landsat visible band spectral data for those same locations to establish a relationship between the spectral data, CDOM absorption coefficients. This allowed us to spatially map CDOM absorption coefficients in the Gulf of Mexico using the Landsat spectral data in GIS. We then used a multiple linear regressions model to derive DOC concentrations from the CDOM absorption coefficients and applied those to our map. This study provides an evaluation of the viability of scaling up CDOM absorption coefficient and remote-sensing derived estimates of DOC concentrations to the scale of the LA-TX shelf ecosystem.

Strontium-90 in the western Gulf of Mexico

International Nuclear Information System (INIS)

Payton, P.H.; Hild, S.B.; Oertti, C.U.; Suttle, A.D. Jr.

1977-01-01

The results of measurements of 90 Sr in water, coral, hermit crabs and molluscs from the western Gulf of Mexico and in fresh water molluscs from Canyon Lake, Texas are reported. Preparation of samples for measurement in the anticoincidence mode in a lead shielded flow proportional counter is described. The measured value of 0.095 +- 0.003 pCi/litre for Gulf water is in accord with literature values. Concentration factors for 90 Sr are apparently 1 for coral. The activity incorporated into shells normalized to calcium content, decreases from Galveston to Campeche Bay. (U.K.)

Home range and habitat use of juvenile green turtles (Chelonia mydas) in the northern Gulf of Mexico

Science.gov (United States)

Lamont, Margaret M.; Fujisaki, Ikuko; Stephens, Brail S.; Hackett, Caitlin

2015-01-01

Background: For imperiled marine turtles, use of satellite telemetry has proven to be an effective method in determining long distance movements. However, the large size of the tag, relatively high cost and low spatial resolution of this method make it more difficult to examine fine-scale movements of individuals, particularly at foraging grounds where animals are frequently submerged. Acoustic telemetry offers a more suitable method of assessing fine-scale movement patterns with a smaller tag that provides more precise locations. We used acoustic telemetry to define home ranges and describe habitat use of juvenile green turtles at a temperate foraging ground in the northern Gulf of Mexico.

Mobile Bay turbidity plume study

Science.gov (United States)

Crozier, G. F.

1976-01-01

Laboratory and field transmissometer studies on the effect of suspended particulate material upon the appearance of water are reported. Quantitative correlations were developed between remotely sensed image density, optical sea truth data, and actual sediment load. Evaluation of satellite image sea truth data for an offshore plume projects contours of transmissivity for two different tidal phases. Data clearly demonstrate the speed of change and movement of the optical plume for water patterns associated with the mouth of Mobile bay in which relatively clear Gulf of Mexico water enters the bay on the eastern side. Data show that wind stress in excess of 15 knots has a marked impact in producing suspended sediment loads.

A New View of Glacial Age Coastal Wetlands from A Well-Preserved Underwater Baldcypress Forest in the Northern Gulf of Mexico

Science.gov (United States)

DeLong, K. L.; Harley, G. L.; Bentley, S. J.; Xu, K.; Reese, A.; Caporaso, A.; Obelcz, J.; Gonzalez Rodriguez, S. M.; Truong, J. T.; Shen, Z.; Raines, B.

2017-12-01

A unique site in the northern Gulf of Mexico contains well-preserved baldcypress (Taxodium distichum) stumps in life position deposited when sea level was lower during the last glacial interval presumably uncovered by Hurricane Ivan in 2004. Previous pollen and climate model studies suggest the southeastern USA was cold and dry during the glacial with boreal forests; however, little paleo-evidence for the northern gulf coast exist. Wood normally decomposes quickly in marine environments thus such sites are rare and understudied until this multi-disciplinary team began studying the site in 2012. The team has dived the site collecting 23 wood samples, conducted two geophysical surveys, and recovered 18 vibracores. Radiocarbon dating of tree stumps reveal that the trees are radiocarbon dead yet some dates from the woody fractions in the sediments above the trees have 14C ages from 37,350-41,830 years BP, which are close to the 14C dating limitations. Optically stimulated luminescence dating pushes burial of the forest back to 60-70 ka. Based on the site location (13.5 km offshore), water depth (18 m), and relative tectonic stability of this area, and geophysical surveys, these subtropical baldcypress trees lived 30 m above sea level in a backwater swamp in an area with topographic relief during a lower sea level stand in the last glacial interval (MIS 3-4) near the now buried and incised Mobile River channels. Pollen analysis from sediment core samples found an abundance of baldcypress and tupelo (Nyssa aquatic)with some pine pollen similar to the modern northern Gulf Coast. We developed a floating tree-ring chronology spanning 489 years using wood samples with bark still intact. This chronology reveals growth suppression events towards the end of their life with death occurring simultaneously and burial possibly caused by floodplain aggradation from a quick rise in sea level during the glacial interval. These large baldcypress trees and pollen results suggest the

33 CFR 162.65 - All waterways tributary to the Atlantic Ocean south of Chesapeake Bay and all waterways tributary...

Science.gov (United States)

2010-07-01

... Atlantic Ocean south of Chesapeake Bay and all waterways tributary to the Gulf of Mexico east and south of... All waterways tributary to the Atlantic Ocean south of Chesapeake Bay and all waterways tributary to..., which are tributary to or connected by other waterways with the Atlantic Ocean south of Chesapeake Bay...

Botryosphaeriaceae species associated with dieback and canker disease of bay laurel in northern California with the description of Dothiorella californica sp. nov.

Science.gov (United States)

Lawrence, Daniel P; Peduto Hand, Francesca; Gubler, W Douglas; Trouillas, Florent P

2017-04-01

Members of the Botryosphaeriaceae are cosmopolitan fungi that may exist as seemingly innocuous endophytes or as destructive pathogens of numerous woody hosts, including fruit and nut crops, urban ornamental trees and shrubs, and forest trees. Surveys of bay laurel in northern California have revealed symptoms of dieback and branch canker of unknown aetiology. The goals of this study were to identify and clarify the species of Botryosphaeriaceae associated with these symptoms and to confirm their pathogenicity. To understand the role of members of the Botryosphaeriaceae in the dieback and canker disease of bay laurel, 23 isolates were isolated from symptomatic wood. Phylogenetic analyses of ITS, translation elongation factor 1-α, and beta-tubulin revealed three species: Botryosphaeria dothidea, Neofusicoccum nonquaesitum, and the newly described and typified species Dothiorella californica sp. nov. When select isolates were inoculated to 2- to 3-year-old branches of Umbellularia californica in a natural forest, both B. dothidea and N. nonquaesitum were pathogenic with N. nonquaesitum producing the largest lesions at 12- and 18-months post inoculation, respectively, while Do. californica did not cause wood lesions significantly greater than the mock-inoculated controls. This study represents the first attempt to identify and test the pathogenicity of Botryosphaeriaceae species associated with dieback and canker disease of bay laurel in a northern California forest. Copyright © 2016 British Mycological Society. All rights reserved.

GIS of selected geophysical and core data in the northern Gulf of Mexico continental slope collected by the U.S. Geological Survey

Science.gov (United States)

Twichell, David C.; Cross, VeeAnn A.; Paskevich, Valerie F.; Hutchinson, Deborah R.; Winters, William J.; Hart, Patrick E.

2006-01-01

Since 1982 the U. S. Geological Survey (USGS) has collected a large amount of surficial and shallow subsurface geologic information in the deep-water parts of the US EEZ in the northern Gulf of Mexico. These data include digital sidescan sonar imagery, digital seismic-reflection data, and descriptions and analyses of piston and gravity cores. The data were collected during several different projects that addressed surficial and shallow subsurface geologic processes. Some of these datasets have already been published, but the growing interest in the occurrence and distribution of gas hydrates in the Gulf of Mexico warrants integrating these existing USGS datasets and associated interpretations into a Geographic Information System (GIS) to provide regional background information for ongoing and future gas hydrate research. This GIS is organized into five different components that contain (1) information needed to develop an assessment of gas hydrates, (2) background information for the Gulf of Mexico, (3) cores collected by the USGS, (4) seismic surveys conducted by the USGS, and (5) sidescan sonar surveys conducted by the USGS. A brief summary of the goals and findings of the USGS field programs in the Gulf of Mexico is given in the Geologic Findings section, and then the contents of each of the five data categories are described in greater detail in the GIS Data Catalog section.

Genetic Connectivity in Scleractinian Corals across the Northern Gulf of Mexico: Oil/Gas Platforms, and Relationship to the Flower Garden Banks

OpenAIRE

Sammarco, Paul W.; Brazeau, Daniel A.; Sinclair, James

2012-01-01

The 3,000 oil/gas structures currently deployed in the northern Gulf of Mexico (GOM) provide hard substratum for marine organisms in a region where such has been rare since the Holocene. The major exception to this are the Flower Garden Banks (FGB). Corals are known to have colonized oil/gas platforms around the FGB, facilitating biogeographic expansion. We ask the question, what are the patterns of genetic affinity in these coral populations. We sampled coral tissue from populations of two s...

Topobathymetric model of Mobile Bay, Alabama

Science.gov (United States)

Danielson, Jeffrey J.; Brock, John C.; Howard, Daniel M.; Gesch, Dean B.; Bonisteel-Cormier, Jamie M.; Travers, Laurinda J.

2013-01-01

Topobathymetric Digital Elevation Models (DEMs) are a merged rendering of both topography (land elevation) and bathymetry (water depth) that provides a seamless elevation product useful for inundation mapping, as well as for other earth science applications, such as the development of sediment-transport, sea-level rise, and storm-surge models. This 1/9-arc-second (approximately 3 meters) resolution model of Mobile Bay, Alabama was developed using multiple topographic and bathymetric datasets, collected on different dates. The topographic data were obtained primarily from the U.S. Geological Survey (USGS) National Elevation Dataset (NED) (http://ned.usgs.gov/) at 1/9-arc-second resolution; USGS Experimental Advanced Airborne Research Lidar (EAARL) data (2 meters) (http://pubs.usgs.gov/ds/400/); and topographic lidar data (2 meters) and Compact Hydrographic Airborne Rapid Total Survey (CHARTS) lidar data (2 meters) from the U.S. Army Corps of Engineers (USACE) (http://www.csc.noaa.gov/digitalcoast/data/coastallidar/). Bathymetry was derived from digital soundings obtained from the National Oceanic and Atmospheric Administration’s (NOAA) National Geophysical Data Center (NGDC) (http://www.ngdc.noaa.gov/mgg/geodas/geodas.html) and from water-penetrating lidar sources, such as EAARL and CHARTS. Mobile Bay is ecologically important as it is the fourth largest estuary in the United States. The Mobile and Tensaw Rivers drain into the bay at the northern end with the bay emptying into the Gulf of Mexico at the southern end. Dauphin Island (a barrier island) and the Fort Morgan Peninsula form the mouth of Mobile Bay. Mobile Bay is 31 miles (50 kilometers) long by a maximum width of 24 miles (39 kilometers) with a total area of 413 square miles (1,070 square kilometers). The vertical datum of the Mobile Bay topobathymetric model is the North American Vertical Datum of 1988 (NAVD 88). All the topographic datasets were originally referenced to NAVD 88 and no transformations

Concentrations and sources of polycyclic aromatic hydrocarbons in surface coastal sediments of the northern Gulf of Mexico

Science.gov (United States)

2014-01-01

Background Coastal sediments in the northern Gulf of Mexico have a high potential of being contaminated by petroleum hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), due to extensive petroleum exploration and transportation activities. In this study we evaluated the spatial distribution and contamination sources of PAHs, as well as the bioavailable fraction in the bulk PAH pool, in surface marsh and shelf sediments (top 5 cm) of the northern Gulf of Mexico. Results PAH concentrations in this region ranged from 100 to 856 ng g−1, with the highest concentrations in Mississippi River mouth sediments followed by marsh sediments and then the lowest concentrations in shelf sediments. The PAH concentrations correlated positively with atomic C/N ratios of sedimentary organic matter (OM), suggesting that terrestrial OM preferentially sorbs PAHs relative to marine OM. PAHs with 2 rings were more abundant than those with 5–6 rings in continental shelf sediments, while the opposite was found in marsh sediments. This distribution pattern suggests different contamination sources between shelf and marsh sediments. Based on diagnostic ratios of PAH isomers and principal component analysis, shelf sediment PAHs were petrogenic and those from marsh sediments were pyrogenic. The proportions of bioavailable PAHs in total PAHs were low, ranging from 0.02% to 0.06%, with higher fractions found in marsh than shelf sediments. Conclusion PAH distribution and composition differences between marsh and shelf sediments were influenced by grain size, contamination sources, and the types of organic matter associated with PAHs. Concentrations of PAHs in the study area were below effects low-range, suggesting a low risk to organisms and limited transfer of PAHs into food web. From the source analysis, PAHs in shelf sediments mainly originated from direct petroleum contamination, while those in marsh sediments were from combustion of fossil fuels. PMID:24641695

Structure and Stratigraphy of the Rift Basins in the Northern Gulf of California: Results from Analysis of Seismic Reflection and Borehole Data.

Science.gov (United States)

Martín, A.; González, M.; Helenes, J.; García, J.; Aragón, M.; Carreño, A.

2008-12-01

The northern Gulf of California contains two parallel, north-south trending rift basin systems separated by a basement-high. The interpretation of several exploration wells, and ~4500 km of seismic reflection data from PEMEX (Mexican national oil company) indicate that the tectonically active basins to the west (Wagner- Consag and Upper Delfin basins) may have initiated synchronously with the now abandoned Tiburón- Tepoca-Altar basins to the east in the Sonora margin. In both basin systems the lower sequence (A) is marine mudstone-siltstone, has parallel reflectors and a largely uniform thickness that reaches up to1.5 km, and gradually pinches out toward the lateral margins. This suggests that the unit was deposited prior to their segmentation by transtensional faulting. Marine microfossils from borehole samples from sequence A in the Tiburón and Consag basins indicates middle Miocene (>11.2 Ma) proto-Gulf conditions. Sequence B conformably overlies sequence A, and is characterized by up to 2 km growth strata with a fanning geometry that show a clear genetic relationship to the major transtensional faults that control the segmentation of the two basin systems. Sequence C in the Tiburón and Tepoca basins is comparatively thin (<800 m) and includes several unconformities, but is much less affected by faulting. In contrast, sequence C in the active Wagner, Consag and Upper Delfin basin is a much thicker (up to 2 km) growth sequence with abundant volcanic intrusions. Marked variations in sequence C in the different basin systems clearly demonstrate a major westward shift of deformation and subsidence at this time. The modern depocenter in Wagner-Consag basins is controlled by the Consag and Wagner faults, which trend parallel to the north ~20 km apart, and show opposite normal offset. These two faults merge at an oblique angle (70°-50°, respectively) into the Cerro Prieto transform fault to the north and likely accommodate an important amount of dextral shear. To

Benthic harpacticoid copepods of Jiaozhou Bay, Qingdao

Science.gov (United States)

Ma, Lin; Li, Xinzheng

2017-09-01

The species richness of benthic harpacticoid copepod fauna in Jiaozhou Bay, Qingdao, on the southern coast of Shandong Peninsula, has not been comprehensively studied. We present a preliminary inventory of species for this region based on material found in nine sediment samples collected from 2011 to 2012. Our list includes 15 species belonging to 15 genera in 9 families, the most speciose family was the Miraciidae Dana, 1846 (seven species); all other families were represented by single species only. Sediment characteristics and depth are determined to be important environmental determinants of harpacticoid distribution in this region. We briefly detail the known distributions of species and provide a key to facilitate their identification. Both harpacticoid species richness and the species/genus ratio in Jiaozhou Bay are lower than in Bohai Gulf and Gwangyang Bay. The poor knowledge of the distribution of benthic harpacticoids, in addition to low sampling effort in Jiaozhou Bay, likely contribute to low species richness.

Marine hypoxia/anoxia as a source of CH4 and N2O

Digital Repository Service at National Institute of Oceanography (India)

Naqvi, S.W.A.; Bange, H.W.; Farias, L.; Monteiro, P.M.S.; Scranton, M.I.; Zhang, J.

” of the Louisiana Shelf in the northern Gulf of Mexico (Rabal- ais et al., 2007; Swarzenski et al., 2008). All natural O2- deficient aquatic environments have arguably been affected by human activities to varying degrees. Nonetheless, it is possible in most cases... to identify the dominant driver of hy- poxia. Thus, out of the systems being examined here (Fig. 1), hypoxia in the East China Sea, Chesapeake Bay, Gulf of Mexico and Tokyo Bay is largely human-induced, whereas in the remaining regions it is primarily...

Body size structure, biometric relationships and density of Chiton albolineatus (Mollusca: Polyplacophora) on the intertidal rocky zone of three islands of Mazatlan Bay, SE of the Gulf of California

OpenAIRE

Flores-Campaña, Luis Miguel; Arzola-González, Juan Francisco; de León-Herrera, Ramón

2012-01-01

Populations of the polyplacophoran mollusk Chiton albolineatus were studied at 6 sites with different wave exposure of the rocky shores of 3 islands of Mazatlan Bay (southeastern side of the Gulf of California). This chiton species is endemic to the Mexican Pacific coast. Chitons were sampled on wave-exposed and wave-protected sites in the intertidal zone of these islands from January to December 2008 to determine its demographic patterns based on density and body size. Length (L), breadth (B...

Benthic fluxes of mercury during redox changes in pristine coastal marine sediments from the Gulf of Trieste (northern Adriatic Sea)

Energy Technology Data Exchange (ETDEWEB)

Koron, Neza [National Institute of Biology, Piran (Slovenia). Marine Biological Section; Faganeli, Jadran [National Institute of Biology, Piran (Slovenia). Marine Biological Section; Jozef Stefan Institute, Ljubljana (Slovenia). Dept. of Environmental Sciences

2012-12-15

Purpose: The Gulf of Trieste (northern Adriatic Sea) is an example of a coastal environment contaminated with mercury (Hg). Contamination is a consequence of nearly 500 years of activity at the Idrija Mine (western Slovenia), which is the second largest Hg mine in the world. Oxygen depletion can be common in the Gulf of Trieste due to late summer stratification of the water column and accumulation of labile organic matter. Since changing redox conditions can have an impact on Hg transformations, we studied the effect of oxygen depletion, in parallel with sulphide, iron (Fe), manganese (Mn), fluorescent dissolved organic matter (FDOM) and nitrogen (N) and phosphorus (P) availability, on total Hg and methylmercury (MeHg) fluxes from sediments. Materials and methods: Pore water concentrations and benthic fluxes of total dissolved Hg and MeHg were studied in situ and in microcosm laboratory experiments using flux chambers encompassing three different stages: oxic, anoxic and reoxidation. Results and discussion: Our experiments showed that in the oxic stage there were small effluxes of MeHg to the water column, which increased in the anoxic stage and dropped rapidly in a subsequent reoxic stage, showing influx. Our results support the hypothesis that MeHg desorption from reduced metal hydroxides under anoxic conditions, and co-precipitation with Fe-oxides and MeHg demethylation in the reoxidation stage, may play a major role in determining MeHg benthic fluxes. For Hg and MeHg, it appears that there is little relationship between their pore water distribution and flux and that of FDOM, i.e. humics. Conclusions: The results indicate that there was no significant difference in Hg and MeHg pore water levels and their benthic fluxes between the contaminated northern and central parts of the Gulf of Trieste and the pristine southern part. This suggests that shallow and stratified coastal marine environments, in general, represent areas with a risk of high benthic release of

Investigating the use of oil platform marine fouling invertebrates as monitors of oil exposure in the Northern Gulf of Mexico.

Science.gov (United States)

Pie, Hannah V; Heyes, Andrew; Mitchelmore, Carys L

2015-03-01

The concentration of 51 parent and alkylated PAHs was examined in oysters, Ostrea equestris, and corals, Tubastrea coccinea, collected from oil-rig structures off the coast of Louisiana during April and May 2011 to investigate their potential use as monitors for offshore contamination events. Corals and oysters collected from both sampling trips had lower PAH accumulation than most bivalves collected in previous studies near the shoreline of Louisiana and elsewhere in the Gulf of Mexico. In April, total PAH (TPAH) concentrations ranged from 8.73 to 15.17 ng g(-1) in corals and 2.52 to 22.04 ng g(-1) in oysters. In May, corals and oysters had elevated concentrations of TPAH ranging from 24.28 to 79.23 ng g(-1) and 7.18 to 95.55 ng g(-1), respectively. This increase could be a result of Mississippi River flooding that occurred during that time, as evidenced by the high perylene concentrations (3.92-41.49 ng g(-1)) measured in May oysters. Oysters and corals collected in May from MC21B, the closest rig to the Mississippi River Delta, had the highest TPAH concentrations observed among all locations and the only rig to have predominantly petrogenic source inputs. Overall, given the low baseline of PAHs demonstrated in this study and the rapid accumulation of diagnostic chemicals in response to a possible contamination event (i.e. sediment plume from May flooding), oil-rig invertebrates could make excellent monitoring tools to examine the exposure to and recovery from oil (and oil-spill response options) in the offshore Northern Gulf of Mexico. Pre-spill baseline data of chemical and biological biomarkers of contamination is key to better estimating the impacts and recovery of oil exposure. Therefore, this screen of PAH accumulation represents a crucial first step in determining baseline contaminant levels in order to utilize these unique resources as monitors for offshore oil exposure in the Northern Gulf of Mexico. Copyright © 2014 Elsevier B.V. All rights reserved.

On watermass mixing ratios and regenerated silicon in the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Rao, D.P.; Sarma, V.V.; Rao, V.S.; Sudhakar, U.; Gupta, G.V.M.

Regeneration of silicon on mixing in the Bay of Bengal have been computed from six water masses [Bay of Bengal low saline water (BBLS), Bay of Bengal subsurface water (BBSS), northern southeast high salinity water (NSEHS), north Indian intermediate...

Migration, foraging, and residency patterns for Northern Gulf loggerheads: implications of local threats and international movements.

Directory of Open Access Journals (Sweden)

Kristen M Hart

Full Text Available Northern Gulf of Mexico (NGoM loggerheads (Caretta caretta make up one of the smallest subpopulations of this threatened species and have declining nest numbers. We used satellite telemetry and a switching state-space model to identify distinct foraging areas used by 59 NGoM loggerheads tagged during 2010-2013. We tagged turtles after nesting at three sites, 1 in Alabama (Gulf Shores; n = 37 and 2 in Florida (St. Joseph Peninsula; n = 20 and Eglin Air Force Base; n = 2. Peak migration time was 22 July to 9 August during which >40% of turtles were in migration mode; the mean post-nesting migration period was 23.0 d (±13.8 d SD. After displacement from nesting beaches, 44 turtles traveled to foraging sites where they remained resident throughout tracking durations. Selected foraging locations were variable distances from tagging sites, and in 5 geographic regions; no turtles selected foraging sites outside the Gulf of Mexico (GoM. Foraging sites delineated using 50% kernel density estimation were located a mean distance of 47.6 km from land and in water with mean depth of -32.5 m; other foraging sites, delineated using minimum convex polygons, were located a mean distance of 43.0 km from land and in water with a mean depth of -24.9 m. Foraging sites overlapped with known trawling activities, oil and gas extraction activities, and the footprint of surface oiling during the 2010 Deepwater Horizon oil spill (n = 10. Our results highlight the year-round use of habitats in the GoM by loggerheads that nest in the NGoM. Our findings indicate that protection of females in this subpopulation requires both international collaborations and management of threats that spatially overlap with distinct foraging habitats.

Gulf of Mexico killer whale photo-ID catalog

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Photo-identification data on killer whales occupying the northern Gulf of Mexico have been collected in association with large vessel surveys since 1991. Photographs...

Natural radionuclides in bauxitic tailings (Red-Mud) in the Gulf of Corinth, Greece

International Nuclear Information System (INIS)

Papatheodorou, G.; Maratou, A.; Ferentinos, G.; Papaefthymiou, H.

2004-01-01

A detailed environmental survey was carried out in the central Gulf of Corinth in order to determine radionuclides in the bauxite ed-mud tailings which have been discharged on the sea floor by a Bauxite Processing Plant (Aluminio Ellados A.E). The discharge of bauxitic tailings via two pipelines at a water depth of 100 m, in Antikyra Bay (Northern Gulf of Corinth), has resulted in the formation of two red-mud mound-like deposits. The red-mud deposits at the mouth of the out falls, are not stable and very often red-mud masses are detached from the two main deposits and are transported to the Corinth central basin, by turbidity currents, at a water depth of 850 m and about 17 km away from the main deposits. Thus, at the Antikyra bay, the red-mud has formed a surficial veneer (0.5-2.0 cm) on the sea floor. On the Corinth central basin floor the red mud has formed successive red-mud layers which are interrupted by layers of natural mud. Fifteen gravity cores have been selected from the studied area and a number of bauxite samples have been collected from mines that supply the bauxite processing plant. Red-mud, natural mud and bauxite samples were analyzed for 238 U 226 Ra, 232 Th, 40 K, and 137 Cs by direct gamma spectrometry. The study of radionuclides concentrations has shown that: (a) the enrichment factor of radionuclides in the red-mud in the main deposit at the mouth of the out falls, in relation to bauxite samples, is about 2.0, (b) the enrichment factor of 238 U, 226 Ra and 232 Th in the red-mud in the main deposit and the central basin, in relation to natural sediments below, is visibly higher than 1.0 (2.0-19.0) whilst 40 K exhibits the opposite trend, and (c) the enrichment/dilution factor of radionuclides in the red-mud surficial veneer at the Antikyra Bay, in relation to the natural sediments below, is ranging between 0.4 and 3.5. (author)

[Mercury concentration of fish in Tokyo Bay and the surrounding sea area].

Science.gov (United States)

Zhang, R; Kashima, Y; Matsui, M; Okabe, T; Doi, R

2001-07-01

Total mercury in the muscles of three fish species was analyzed in fish caught in Tokyo Bay and the surrounding sea areas, Sagami Bay and Choshi. Tokyo Bay is a semi-closed sea area surrounded by Tokyo, Kanagawa and Chiba prefectures. Sagami Bay and Choshi are open to the Pacific Ocean. A total of 412 fish consisting of northern whiting (Sillago japonica), flatfish (Limanda yokohamae) and sardine (Sardinops melanosticta) were caught in these areas over a 6 months period from November 1998 to April 1999. Total mercury concentration ranged from 0.008-0.092 microgram/g (wet wt.) in northern whiting, 0.006-0.065 microgram/g in flatfish and 0.001-0.045 microgram/g in sardine. All concentrations were below the restriction limit of fish mercury in Japan, 0.4 microgram/g of total mercury concentration. A significant correlation was found between mercury concentrations and body length or body weight in northern whiting and flatfish, irrespective of the sea area. A correlation was also found between mercury concentration in fish and their feeding habits: among the 3 species caught in the same area, crustacean feeding northern whiting had the highest, polychaete feeding flatfish moderate, and plankton feeding sardine had the lowest mercury concentration. In a comparison of mercury concentration in the same species caught in different sea areas, a higher concentration was noted in fish caught in the semi-closed sea area of Tokyo Bay, than in fish caught in the open sea areas of Sagami Bay and Choshi. This difference was most marked in fish caught at the bottom of Tokyo Bay and we considered that the mercury concentration of seawater and sediment in these areas was the cause of mercury accumulation in fish. These findings suggest that improved water quality control and environmental monitoring is necessary in semi-closed sea areas such as Tokyo Bay.

Mercury concentrations, speciation, and isotopic composition in sediment from a cold seep in the northern Gulf of Mexico

International Nuclear Information System (INIS)

Brown, Garry; Sleeper, Kenneth; Johnson, Marcus W.; Blum, Joel D.; Cizdziel, James V.

2013-01-01

Highlights: • T-Hg, MMHg, and Hg isotopes were determined in Gulf of Mexico deep marine sediments. • Levels of mass independent fractionation of Hg isotopes varied from coastal sediments. • Levels of the MMHg were only slightly elevated at the cold seep site. • Cold seeps do not appear to be significant sources of MMHg to Gulf of Mexico waters. -- Abstract: Total-Hg, monomethylmercury (MMHg), and mercury isotopic composition was determined in sediment from a cold seep and background sites in the northern Gulf of Mexico (nGoM). Total-Hg averaged 50 ng/g (n = 28), ranged from 31 to 67 ng/g, and decreased with depth (0–15 cm). MMHg averaged 0.91 ng/g (n = 18), and ranged from 0.2 to 1.9 ng/g. There was no significant difference for total-Hg or MMHg between cold seep and background sites. δ 202 Hg ranged from −0.5 to −0.8‰ and becomes more negative with depth (r = 0.989). Mass independent fractionation (Δ 199 Hg) was small but consistently positive (0.04–0.12‰); there was no difference between cold seeps (Δ 199 Hg = +0.09 ± 0.03; n = 7, 1SD) and background sites (Δ 199 Hg = +0.07 ± 0.02; n = 5, 1SD). This suggests that releases of hydrocarbons at the cold seep do not significantly alter Hg levels, and that cold seeps are likely not major sources of MMHg to nGoM waters

Gulf of Mexico dissolved oxygen model (GoMDOM) research and quality assurance project plan

Science.gov (United States)

An integrated high resolution mathematical modeling framework is being developed that will link hydrodynamic, atmospheric, and water quality models for the northern Gulf of Mexico. This Research and Quality Assurance Project Plan primarily focuses on the deterministic Gulf of Me...

Population parameters and dynamic pool models of commercial fishes in the Beibu Gulf, northern South China Sea

Science.gov (United States)

Wang, Xuehui; Qiu, Yongsong; Du, Feiyan; Lin, Zhaojin; Sun, Dianrong; Huang, Shuolin

2012-01-01

Length-frequency data of eight commercial fish species in the Beibu Gulf (Golf of Tonkin), northern South China Sea, were collected during 2006-2007. Length-weight relationships and growth and mortality parameters were analyzed using FiSAT II software. Five species had isometric growth, two species had negative allometric growth, and one species had positive allometric growth. Overall, the exploitation rates of the eight species were lower in 2006-2007 than in 1997-1999: for four species ( Saurida tumbil, Saurida undosquamis, Argyrosomus macrocephalus, and Nemipterus virgatus) it was lower in 2006-2007 than in 1997-1999, for two species ( Parargyrops edita and Trichiurus haumela) it remained the same, and for the other two species ( Trachurus japonicus and Decapterus maruadsi) it was higher in 2006-2007 than in 1997-1999. The exploitation rates might have declined because of the decline in fishing intensity caused by high crude oil prices. The optimum exploitation rate, estimated using Beverton-Holt dynamic pool models, indicated that although fishes in the Beibu Gulf could sustain high exploitation rates, the under-size fishes at first capture resulted in low yields. To increase the yield per recruitment, it is more effective to increase the size at first capture than to control fishing effort.

Seasonal Cycle of the Near-Surface Diurnal Wind Field Over the Bay of La Paz, Mexico

Science.gov (United States)

Turrent, Cuauhtémoc; Zaitsev, Oleg

2014-05-01

The results of numerical simulations of the troposphere over the Bay of La Paz, calculated for the months of January, April, July and October during the period 2006-2010 with the Weather Research and Forecast (WRF v3.5) regional model, are used to describe the seasonal features of the diurnal cycle of planetary boundary-layer winds. Two distinct near-surface diurnal flows with strong seasonal variability were identified: (1) a nocturnal and matutinal breeze directed from the subtropical Pacific Ocean, over the Baja California peninsula and the Bay of La Paz, into the Gulf of California that is associated with the regional sea-surface temperature difference between those two major water bodies; and (2) a mid to late afternoon onshore sea-breeze related to the peninsula's daily cycle of insolation heating that evolves with counter-clockwise rotation over the Bay of La Paz. The model results reveal the interaction over Baja California of opposing afternoon sea-breeze fronts that originate from the subtropical Pacific Ocean and the Gulf of California, with a convergence line forming over the peaks of the peninsula's topography and the associated presence of a closed vertical circulation cell over the Bay of La Paz and the adjacent Gulf. The collision of the opposing sea-breeze fronts over the narrow peninsula drives convection that is relatively weak due to the reduced heat source and only appears to produce precipitation sporadically. The spatial structure of the sea-breeze fronts over the Bay of La Paz region is complex due to shoreline curvature and nearby topographic features. A comparison of the numerical results with available meteorological near-surface observations indicates that the modelling methodology adequately reproduced the observed features of the seasonal variability of the local planetary boundary-layer diurnal wind cycle and confirms that the low-level atmospheric circulation over the Bay of La Paz is dominated by kinetic energy in the diurnal band

Coral reef fish assemblages along a disturbance gradient in the northern Persian Gulf: A seasonal perspective.

Science.gov (United States)

Ghazilou, Amir; Shokri, Mohammad Reza; Gladstone, William

2016-04-30

Seasonal dynamics of coral reef fish assemblages were assessed along a gradient of potential anthropogenic disturbance in the Northern Persian Gulf. Overall, the attributes of coral reef fish assemblages showed seasonality at two different levels: seasonal changes irrespective of the magnitude of disturbance level (e.g. species richness), and seasonal changes in response to disturbance level (e.g. total abundance and assemblage composition). The examined parameters mostly belonged to the second group, but the interpretation of the relationship between patterns of seasonal changes and the disturbance level was not straightforward. The abundance of carnivorous fishes did not vary among seasons. SIMPER identified the family Nemipteridae as the major contributor to the observed spatiotemporal variations in the composition of coral reef fish assemblages in the study area. Copyright © 2015 Elsevier Ltd. All rights reserved.

Petroleum hydrocarbons in sediment from the northern Gulf of Mexico shoreline, Texas to Florida

Science.gov (United States)

Rosenbauer, Robert J.; Campbell, Pamela L.; Lam, Angela; Lorenson, T.D.; Hostettler, Frances D.; Thomas, Burt; Wong, Florence L.

2011-01-01

Petroleum hydrocarbons were extracted and analyzed from shoreline sediment collected from the northern Gulf of Mexico (nGOM) coastline that could potentially be impacted by Macondo-1 (M-1) well oil. Sediment was collected before M-1 well oil made significant local landfall and analyzed for baseline conditions by a suite of diagnostic petroleum biomarkers. Oil residue in trace quantities was detected in 45 of 69 samples. With the aid of multivariate statistical analysis, three different oil groups, based on biomarker similarity, were identified that were distributed geographically along the nGOM from Texas to Florida. None of the sediment hydrocarbon extracts correlated with the M-1 well oil extract, however, the similarity of tarballs collected at one site (FL-18) with the M-1 well oil suggests that some oil from the Deepwater Horizon spill may have been transported to this site in the Florida Keys, perhaps by a loop current, before that site was sampled.

Movements and habitat-use of loggerhead sea turtles in the northern Gulf of Mexico during the reproductive period.

Directory of Open Access Journals (Sweden)

Kristen M Hart

Full Text Available Nesting strategies and use of important in-water habitats for far-ranging marine turtles can be determined using satellite telemetry. Because of a lack of information on habitat-use by marine turtles in the northern Gulf of Mexico, we used satellite transmitters in 2010 through 2012 to track movements of 39 adult female breeding loggerhead turtles (Caretta caretta tagged on nesting beaches at three sites in Florida and Alabama. During the nesting season, recaptured turtles emerged to nest 1 to 5 times, with mean distance between emergences of 27.5 km; however, several turtles nested on beaches separated by ~250 km within a single season. Mean total distances traveled throughout inter-nesting periods for all turtles was 1422.0 ± 930.8 km. In-water inter-nesting sites, delineated using 50% kernel density estimation (KDE, were located a mean distance of 33.0 km from land, in water with mean depth of -31.6 m; other in-water inter-nesting sites, delineated using minimum convex polygon (MCP approach, were located a mean 13.8 km from land and in water with a mean depth of -15.8 m. Mean size of in-water inter-nesting habitats were 61.9 km(2 (50% KDEs, n = 10 and 741.4 km(2 (MCPs, n = 30; these areas overlapped significantly with trawling and oil and gas extraction activities. Abundance estimates for this nesting subpopulation may be inaccurate in light of how much spread there is between nests of the same individual. Further, our results also have consequences for critical habitat designations for northern Gulf loggerheads, as protection of one nesting beach would not encompass the entire range used by turtles during breeding seasons.

Movements and Habitat-Use of Loggerhead Sea Turtles in the Northern Gulf of Mexico during the Reproductive Period

Science.gov (United States)

Hart, Kristen M.; Lamont, Margaret M.; Sartain, Autumn R.; Fujisaki, Ikuko; Stephens, Brail S.

2013-01-01

Nesting strategies and use of important in-water habitats for far-ranging marine turtles can be determined using satellite telemetry. Because of a lack of information on habitat-use by marine turtles in the northern Gulf of Mexico, we used satellite transmitters in 2010 through 2012 to track movements of 39 adult female breeding loggerhead turtles (Caretta caretta) tagged on nesting beaches at three sites in Florida and Alabama. During the nesting season, recaptured turtles emerged to nest 1 to 5 times, with mean distance between emergences of 27.5 km; however, several turtles nested on beaches separated by ∼250 km within a single season. Mean total distances traveled throughout inter-nesting periods for all turtles was 1422.0±930.8 km. In-water inter-nesting sites, delineated using 50% kernel density estimation (KDE), were located a mean distance of 33.0 km from land, in water with mean depth of −31.6 m; other in-water inter-nesting sites, delineated using minimum convex polygon (MCP) approach, were located a mean 13.8 km from land and in water with a mean depth of −15.8 m. Mean size of in-water inter-nesting habitats were 61.9 km2 (50% KDEs, n = 10) and 741.4 km2 (MCPs, n = 30); these areas overlapped significantly with trawling and oil and gas extraction activities. Abundance estimates for this nesting subpopulation may be inaccurate in light of how much spread there is between nests of the same individual. Further, our results also have consequences for critical habitat designations for northern Gulf loggerheads, as protection of one nesting beach would not encompass the entire range used by turtles during breeding seasons. PMID:23843971

The fouling serpulids (Polychaeta: Serpulidae from United States coastal waters: an overview

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J. Rolando Bastida-Zavala

2017-08-01

Full Text Available Serpulids are an important component of fouling communities. This paper provides an overview of the serpulid species found in North America, as part of a broader study of fouling invertebrates focused on NIS (non-indigenous species in United States coastal ecosystems. Almost 4400 serpulid specimens were examined from selected fouling plates. Fouling plates were deployed in 26 bays and coastal lagoons along the continental coasts of the United States and Hawaiian islands, primarily in bays and lagoons with salinities averaging 20‰ or greater. Twenty-five serpulid species were identified, including four new records for the United States (Ficopomatus uschakovi, Hydroides cf. brachyacantha, H. longispinosa and Protula longiseta, three known NIS, two presumed NIS, three cryptogenic serpulids, and several range extensions. Crucigera websteri extends its northward range from Santa Barbara Island to Humboldt Bay, California; Ficopomatus enigmaticus, first recorded in North America from San Francisco, California in 1920, Rockport, Texas in 1952 and Barnegat Bay, New Jersey in 1980, is now recorded at additional localities on the east coast (Chesapeake Bay, Virginia, Charleston, South Carolina and Indian River, Florida and the northern Gulf of Mexico (Galveston Bay, Texas; F. miamiensis extends its westward range from Louisiana to Texas; F. uschakovi, an Indo-Pacific and Western African species, was recorded formally for the first time from the northern Gulf of Mexico (Galveston Bay and Corpus Christi, Texas and the east coast of Florida (Jacksonville. Hydroides cf. brachyacantha extends its northward range from Curaҫao to Pensacola Bay, Florida; H. dirampha from Veracruz, Mexico to Corpus Christi, Texas; H. floridana extends its westward range from Louisiana to Texas; H. gracilis extends its northward range from Pacific Grove to San Francisco, California; Salmacina huxleyi from Cape Hatteras, North Carolina to Rhode Island; and Spirobranchus

Tiered on-the-ground implementation projects for Gulf of Mexico water quality improvements

Science.gov (United States)

Both the Gulf Hypoxia Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico and Improving Water Quality in the Mississippi River Basin (USEPA 2008) and the GOMA Governors’ Action Plan II for Healthy and Resilient Coasts (GOMA 2009) call for the development and ...

Surveys of tidal river systems in the northern territory of Australia and their crocodile populations

Energy Technology Data Exchange (ETDEWEB)

Vorlicek, G.C.; Messel, H.; Green, W.J.

1986-01-01

This book provides an update on the population dynamics of Crocodylus porous in the tidal waterways of Van Diemen Gulf and the Southern Gulf of Carpentaria, Australia, during 1984 and 1985. Contents: Prologue; Dedication; Introduction; Status of Crocodylus porous. July 1984, in the tidal waterways of the Alligator Region and in the Adelaide River System of Northern Australia: recovery underway; Resurvey of Crocodylus porous populations in the tidal waterways of the southern Gulf of Carpentaria, September - October 1985; Local knowledge - Northern Australia style.

Gulf of California species and catch spatial distributions and historical time series - Developing end-to-end models of the Gulf of California

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The purpose of this project is to develop spatially discrete end-to-end models of the northern Gulf of California, linking oceanography, biogeochemistry, food web...

Roebuck Bay Invertebrate and bird Mapping 2006

NARCIS (Netherlands)

Piersma, Theunis; Pearson, Grant B.; Hickey, Robert; Dittmann, Sabine; Rogers, Danny I.; Folmer, Eelke; Honkoop, Pieter; Drent, Jan; Goeij, Petra de; Marsh, Loisette

2006-01-01

1. This is a report on a survey of the benthic ecology of the intertidal flats along the northern shores of Roebuck Bay in June 2006. In the period 11-20 June we mapped both the invertebrate macrobenthic animals (those retained by a 1 mm sieve) over the whole of the northern intertidal area of

Is the biological productivity in the Bay of Bengal light limited?

Digital Repository Service at National Institute of Oceanography (India)

PrasannaKumar, S.; Narvekar, J.; Nuncio, M.; Kumar, A.; Ramaiah, N.; Sardessai, S.; Gauns, M.; Fernandes, V.; Paul, J.

Recent measurements of chlorophyll, primary productivity (PP) and nutrients along the central Bay of Bengal (BOB) during summer, fall and spring intermonsoons showed that the northern bay becomes less productive compared to the south in summer...

Fish larvae from the Gulf of California

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Gerardo Aceves-Medina

2003-03-01

Full Text Available Taxonomic composition of fish larvae was analysed from 464 plankton samples obtained during 10 oceanographic surveys in the Gulf of California between 1984 and 1988. We identified 283 taxa: 173 species, 57 genera, and 53 families. Tropical and subtropical species predominated except during the winter, when temperate-subarctic species were dominant. The most abundant species were the mesopelagic Benthosema panamense, Triphoturus mexicanus and Vinciguerria lucetia, but the coastal pelagic species Engraulis mordax, Opisthonema spp., Sardinops caeruleus and Scomber japonicus were also prominent. The taxonomic composition of the ichthyoplankton shows the seasonality of the Gulf as well as environmental changes that occurred between the 1984-1987 warm period and the 1956-1957 cool period previously reported. The presence of E. mordax larvae as one of the most abundant species in the Gulf provides evidence of the reproduction of this species two years before the development of the northern anchovy fishery and the decline of the sardine fishery in the Gulf of California.

Application of spatial models to the stopover ecology of trans-Gulf migrants

Science.gov (United States)

Theodore R. Simons; Scott M. Pearson; Frank R. Moore

2000-01-01

Studies at migratory stopover sites along the northern coast of the Gulf of Mexico are providing an understanding of how weather, habitat, and energetic factors combine to shape the stopover ecology of trans-Gulf migrants. We are coupling this understanding with analyses of landscape-level patterns of habitat availability by using spatially explicit models to simulate...

The Northern Gulf of Mexico During OAE2 and the Relationship Between Water Depth and Black Shale Development

Science.gov (United States)

Lowery, Christopher M.; Cunningham, Robert; Barrie, Craig D.; Bralower, Timothy; Snedden, John W.

2017-12-01

Despite their name, Oceanic Anoxic Events (OAEs) are not periods of uniform anoxia and black shale deposition in ancient oceans. Shelf environments account for the majority of productivity and organic carbon burial in the modern ocean, and this was likely true in the Cretaceous as well. However, it is unlikely that the mechanisms for such an increase were uniform across all shelf environments. Some, like the northwest margin of Africa, were characterized by strong upwelling, but what might drive enhanced productivity on shelves not geographically suited for upwelling? To address this, we use micropaleontology, carbon isotopes, and sedimentology to present the first record of Oceanic Anoxic Event 2 (OAE2) from the northern Gulf of Mexico shelf. Here OAE2 occurred during the deposition of the well-oxygenated, inner neritic/lower estuarine Lower Tuscaloosa Sandstone. The overlying organic-rich oxygen-poor Marine Tuscaloosa Shale is entirely Turonian in age. We trace organic matter enrichment from the Spinks Core into the deepwater Gulf of Mexico, where wireline log calculations and public geochemical data indicate organic enrichment and anoxia throughout the Cenomanian-Turonian boundary interval. Redox change and organic matter preservation across the Gulf of Mexico shelf were driven by sea level rise prior to the early Turonian highstand, which caused the advection of nutrient-rich, oxygen-poor waters onto the shelf. This results in organic matter mass accumulation rates 1-2 orders of magnitude lower than upwelling sites like the NW African margin, but it likely occurred over a much larger geographic area, suggesting that sea level rise was an important component of the overall increase in carbon burial during OAE2.

Population Structure, Abundance and Movement of Whale Sharks in the Arabian Gulf and the Gulf of Oman.

Science.gov (United States)

Robinson, David P; Jaidah, Mohammed Y; Bach, Steffen; Lee, Katie; Jabado, Rima W; Rohner, Christoph A; March, Abi; Caprodossi, Simone; Henderson, Aaron C; Mair, James M; Ormond, Rupert; Pierce, Simon J

2016-01-01

Data on the occurrence of whale sharks, Rhincodon typus, in the Arabian Gulf and Gulf of Oman were collected by dedicated boat surveys and via a public-sightings scheme during the period from 2011 to 2014. A total of 422 individual whale sharks were photo-identified from the Arabian Gulf and the northern Gulf of Oman during that period. The majority of sharks (81%, n = 341) were encountered at the Al Shaheen area of Qatar, 90 km off the coast, with the Musandam region of Oman a secondary area of interest. At Al Shaheen, there were significantly more male sharks (n = 171) than females (n = 78; X2 = 17.52, P 9 m individuals were visually assessed as pregnant. Connectivity among sharks sighted in Qatari, Omani and UAE waters was confirmed by individual spot pattern matches. A total of 13 identified sharks were re-sighted at locations other than that at which they were first sighted, including movements into and out of the Arabian Gulf through the Strait of Hormuz. Maximum likelihood techniques were used to model an estimated combined population for the Arabian Gulf and Gulf of Oman of 2837 sharks ± 1243.91 S.E. (95% C.I. 1720-6295). The Al Shaheen aggregation is thus the first site described as being dominated by mature males while the free-swimming pregnant females are the first reported from the Indian Ocean.

Nearshore fish survey in northern Bristol Bay, Alaska conducted from 2009-07 to 2009-08 by Alaska Fisheries Science Center, Resource Ecology and Fisheries Management division (NCEI Accession 0144625)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The project consisted of a nearshore fish, invertebrate, and habitat survey in northern Bristol Bay, Alaska. A 32-ft. gillnet vessel, the F/V Willow was chartered...

Seasonal variation in the skin transcriptome of common bottlenose dolphins (Tursiops truncatus from the northern Gulf of Mexico.

Directory of Open Access Journals (Sweden)

Frances M Van Dolah

Full Text Available As long-lived predators that integrate exposures across multiple trophic levels, cetaceans are recognized as sentinels for the health of marine ecosystems. Their utility as sentinels requires the establishment of baseline health parameters. Because cetaceans are protected, measurements obtained with minimal disruption to free ranging animals are highly desirable. In this study we investigated the utility of skin gene expression profiling to monitor health and contaminant exposure in common bottlenose dolphins (Tursiops truncatus. Remote integument biopsies were collected in the northern Gulf of Mexico prior to the Deepwater Horizon oil spill (May 2010 and during summer and winter for two years following oil contamination (2010-2011. A bottlenose dolphin microarray was used to characterize the skin transcriptomes of 94 individuals from three populations: Barataria Bay, Louisiana, Chandeleur Sound, Louisiana, and Mississippi Sound, Mississippi/Alabama. Skin transcriptomes did not differ significantly between populations. In contrast, season had a profound effect on gene expression, with nearly one-third of all genes on the array differing in expression between winter and the warmer seasons (moderated T-test; ptwo-fold higher concentrations in summer compared to winter, due to a seasonal decrease in blubber thickness and loss of stored lipid. However, global gene expression did not correlate strongly with seasonally changing contaminant concentrations, most likely because the refractory, lipid-stored metabolites are not substrates for phase I or II xenobiotic detoxification pathways. Rather, processes related to cell proliferation, motility, and differentiation dominated the differences in expression in winter and the warmer seasons. More subtle differences were seen between spring and summer (1.5% of genes differentially expressed. However, two presumed oil-exposed animals from spring presented gene expression profiles more similar to the summer

Evaluating Aquatic Life Benefits of Reducing Nutrient Loading to Remediate Episodic and Diel Cycling Hypoxia in a Shallow Hypereutrophic Estuary

Science.gov (United States)

Theoretical linkages between excess nutrient loading, nutrient-enhanced community metabolism (i.e., production and respiration), and hypoxia in estuaries are well-understood. In seasonally-stratified estuaries and coastal systems (e.g., Chesapeake Bay, northern Gulf of Mexico), h...

Cd and Pb Concentrations in the Surface Sediments of the Asaluyeh Bay, Iran

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Mansooreh Dehghani

2014-06-01

Conclusion: Therefore, it is essential to use abatement efforts to clean-up the polluted areas in the coastal area of the Asaluyeh Bay and prevent the discharging of the untreated or partially treated wastewater to the Persian Gulf as well.

Reconnaissance of Macondo-1 well oil in sediment and tarballs from the northern Gulf of Mexico shoreline, Texas to Florida

Science.gov (United States)

Rosenbauer, Robert J.; Campbell, Pamela L.; Lam, Angela; Lorenson, T.D.; Hostettler, Frances D.; Thomas, Burt; Wong, Florence L.

2010-01-01

Hydrocarbons were extracted and analyzed from sediment and tarballs collected from the northern Gulf of Mexico (nGOM) coast that is potentially impacted by Macondo-1 (M-1) well oil. The samples were analyzed for a suite of diagnostic geochemical biomarkers. Aided by multivariate statistical analysis, the M-1 well oil has been identified in sediment and tarballs collected from Louisiana, Alabama, Mississippi, and Florida. None of the sediment hydrocarbon extracts from Texas correlated with the M-1 well oil. Oil-impacted sediments are confined to the shoreline adjacent to the cumulative oil slick of the Deepwater Horizon oil spill, and no impact was observed outside of this area.

Carbon Dioxide Variability in the Gulf of Trieste (GOT) in the Northern Adriatic Sea

Science.gov (United States)

Turk, D.; McGillis, W. R.; Malacic, V.; Degrandpre, M.

2008-12-01

Coastal marine regions such as the Gulf of Trieste GOT in the Northern Adriatic Sea serve as the link between carbon cycling on land and the ocean interior and potentially contribute large uncertainties in the estimate of anthropogenic CO2 uptake. This system may be either a sink or a source for atmospheric CO2. Understanding the sources and sinks as a result of biological and physical controls for air-sea carbon dioxide fluxes in coastal waters may substantially alter the current view of the global carbon budget for unique terrestrial and ocean regions such as the GOT. GOT is a semi-enclosed Mediterranean basin situated in the northern part of Adriatic Sea. It is one of the most productive regions in the Mediterranean and is affected by extreme fresh river input, phytoplankton blooms, and large changes of air-sea exchange during Bora high wind events. The unique combination of these environmental processes and relatively small size of the area makes the region an excellent study site for investigations of air-sea interaction, and changes in biology and carbon chemistry. However, there is a dearth of current data or information from the region. Here we present the first measurements of air and water CO2 flux in the GOT. The aqueous CO2 was measured at the Coastal Oceanographic buoy Piran, Slovenia using the SAMI CO2 sensor during spring and late summer and fall 2007. CO2 measurements were combined with hydrological and biological observations to evaluate the processes that control carbon cycling in the region.

Gulf of Mexico Regional Collaborative Final Report

Energy Technology Data Exchange (ETDEWEB)

Judd, Kathleen S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Judd, Chaeli [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Engel-Cox, Jill A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gulbransen, Thomas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, Michael G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Woodruff, Dana L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thom, Ronald M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guzy, Michael [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hardin, Danny [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Estes, Maury [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2007-12-01

cover change at five other bays in the Gulf of Mexico to demonstrate extensibility of the analytical tools; and Initiated development of a conceptual model for understanding the causes and effects of HABs in the Gulf of Mexico IT Tool Development; Established a website with the GoMRC web-based tools at www.gomrc.org; Completed development of an ArcGIS-based decision support tool for SAV restoration prioritization decisions, and demonstrated its use in Mobile Bay; Developed a web-based application, called Conceptual Model Explorer (CME), that enables non-GIS users to employ the prioritization model for SAV restoration; Created CME tool enabling scientists to view existing, and create new, ecosystem conceptual models which can be used to document cause-effect relationships within coastal ecosystems, and offer guidance on management solutions; Adapted the science-driven advanced web search engine, Noesis, to focus on an initial set of coastal and marine resource issues, including SAV and HABs; Incorporated map visualization tools with initial data layers related to coastal wetlands and SAVs; and Supported development of a SERVIR portal for data management and visualization in the southern Gulf of Mexico, as well as training of end users in Mexican Gulf States.

Fluctuations and trends in structure of fish community in Koporskaya Bay coastal waters (Gulf of Finland, Baltic Sea) and influence of water-intake facilities of the Leningrad nuclear power plant on fish fauna

International Nuclear Information System (INIS)

Zimin, V.L.

1996-01-01

The investigation is based on data obtained in 1978-1995 in Koporskaya Bay (eastern part of the Gulf of Finland), known as the cooling water-body of Leningrad (St. Petersburg) nuclear power plant Leningrad (NPP). 45 fish species were recorded in this period. The fish species diversity reduced significantly in last decade (from 8-9 in early 1980s up to 4-5 species in the nucleus of fish community in 1990s). Most vulnerable species, such as salmonids and coregonids, tend to disappear. Koporskaya Bay coastal area is now dominated by abundant three-spined and nine-spined sticklebacks. However, the relatively improved situation have occurred after beginning of reparation works at the 1st reactor unit, when the thermal loading was declined significantly. Great amount of fishes were perished at the water-intake facilities (more than 400 ton/year, in average). Changes in fish community structure caused noticeable changes in commercial fishing: the average percentage part of baltic herring (main object of fishing in the eastern Gulf of Finland) in commercial catches ranged from 90 up to 98% in the time before the LNPP started in operating, but from 1975, especially in last decade when LNPP has reached their project electrical capacity in 1981, we can see significant variations in herring's share (29-80%) in catches

Underwater Gravity Survey of Northern Monterey Bay.

Science.gov (United States)

stations were occupied just above the swash zone. A complete Bouguer anomaly map was drawn and tied in with the previous land surveys and with one...covering the southern half of the bay. The isolines of the complete Bouguer anomaly indicate the relative vertical position of the basement complex Santa

Abundant plankton-sized microplastic particles in shelf waters of the northern Gulf of Mexico.

Science.gov (United States)

Di Mauro, Rosana; Kupchik, Matthew J; Benfield, Mark C

2017-11-01

Accumulation of marine debris is a global problem that affects the oceans on multiple scales. The majority of floating marine debris is composed of microplastics: plastic particles up to 5 mm in diameter. With similar sizes and appearances to natural food items, these small fragments pose potential risks to many marine organisms including zooplankton and zooplanktivores. Semi-enclosed seas are reported to have high concentrations of microplastics, however, the distribution and concentration of microplastics in one such system, the Gulf of Mexico, remains unknown. Our study documented and characterized microplastics in continental shelf waters off the Louisiana coast in the northern Gulf of Mexico, using bongo nets, neuston nets, and Niskin bottles. Additionally, we compared the size distributions of microplastics and zooplankton collected using the nets. Plastics were manually sorted from the samples, documented, and measured using digital microscopy. Confirmation of putative plastics was carried out by hydrofluoric acid digestion and a subsample was analyzed using FTIR microscopy. Estimated concentrations of microplastics collected on the inner continental shelf during this study are among the highest reported globally. Total microplastic concentrations ranged from 4.8 to 8.2 particles m -3 and 5.0-18.4 particles m -3 for the bongo and neuston samples, respectively. Niskin bottles collected smaller plastic particles than the nets and indicated total microplastic concentrations (primarily fibers) from 6.0E4 - 15.7E4 particles m -3 . Microplastic concentrations were greater than the abundances of all but four of the five most abundant taxa from bongo nets and were not statistically different from the abundances of any of the most numerous taxa from neuston nets. Sizes of microplastics and zooplankton partially or completely overlapped, suggesting the potential for confusion with natural prey. Copyright © 2017 Elsevier Ltd. All rights reserved.

Long-Term Observations of Epibenthic Fish Zonation in the Deep Northern Gulf of Mexico

Science.gov (United States)

Wei, Chih-Lin; Rowe, Gilbert T.; Haedrich, Richard L.; Boland, Gregory S.

2012-01-01

A total of 172 bottom trawl/skimmer samples (183 to 3655-m depth) from three deep-sea studies, R/V Alaminos cruises (1964–1973), Northern Gulf of Mexico Continental Slope (NGoMCS) study (1983–1985) and Deep Gulf of Mexico Benthos (DGoMB) program (2000 to 2002), were compiled to examine temporal and large-scale changes in epibenthic fish species composition. Based on percent species shared among samples, faunal groups (≥10% species shared) consistently reoccurred over time on the shelf-break (ca. 200 m), upper-slope (ca. 300 to 500 m) and upper-to-mid slope (ca. 500 to 1500 m) depths. These similar depth groups also merged when the three studies were pooled together, suggesting that there has been no large-scale temporal change in depth zonation on the upper section of the continental margin. Permutational multivariate analysis of variance (PERMANOVA) also detected no significant species changes on the limited sites and areas that have been revisited across the studies (P>0.05). Based on the ordination of the species shared among samples, species replacement was a continuum along a depth or macrobenthos biomass gradient. Despite the well-known, close, negative relationship between water depth and macrofaunal biomass, the fish species changed more rapidly at depth shallower than 1,000 m, but the rate of change was surprisingly slow at the highest macrofaunal biomass (>100 mg C m−2), suggesting that the composition of epibenthic fishes was not altered in response to the extremely high macrofaunal biomass in the upper Mississippi and De Soto Submarine Canyons. An alternative is that the pattern of fish species turnover is related to the decline in macrofaunal biomass, the presumptive prey of the fish, along the depth gradient. PMID:23056412

Long-term observations of epibenthic fish zonation in the deep northern Gulf of Mexico.

Directory of Open Access Journals (Sweden)

Chih-Lin Wei

Full Text Available A total of 172 bottom trawl/skimmer samples (183 to 3655-m depth from three deep-sea studies, R/V Alaminos cruises (1964-1973, Northern Gulf of Mexico Continental Slope (NGoMCS study (1983-1985 and Deep Gulf of Mexico Benthos (DGoMB program (2000 to 2002, were compiled to examine temporal and large-scale changes in epibenthic fish species composition. Based on percent species shared among samples, faunal groups (≥10% species shared consistently reoccurred over time on the shelf-break (ca. 200 m, upper-slope (ca. 300 to 500 m and upper-to-mid slope (ca. 500 to 1500 m depths. These similar depth groups also merged when the three studies were pooled together, suggesting that there has been no large-scale temporal change in depth zonation on the upper section of the continental margin. Permutational multivariate analysis of variance (PERMANOVA also detected no significant species changes on the limited sites and areas that have been revisited across the studies (P>0.05. Based on the ordination of the species shared among samples, species replacement was a continuum along a depth or macrobenthos biomass gradient. Despite the well-known, close, negative relationship between water depth and macrofaunal biomass, the fish species changed more rapidly at depth shallower than 1,000 m, but the rate of change was surprisingly slow at the highest macrofaunal biomass (>100 mg C m(-2, suggesting that the composition of epibenthic fishes was not altered in response to the extremely high macrofaunal biomass in the upper Mississippi and De Soto Submarine Canyons. An alternative is that the pattern of fish species turnover is related to the decline in macrofaunal biomass, the presumptive prey of the fish, along the depth gradient.

Long-term observations of epibenthic fish zonation in the deep northern Gulf of Mexico.

Science.gov (United States)

Wei, Chih-Lin; Rowe, Gilbert T; Haedrich, Richard L; Boland, Gregory S

2012-01-01

A total of 172 bottom trawl/skimmer samples (183 to 3655-m depth) from three deep-sea studies, R/V Alaminos cruises (1964-1973), Northern Gulf of Mexico Continental Slope (NGoMCS) study (1983-1985) and Deep Gulf of Mexico Benthos (DGoMB) program (2000 to 2002), were compiled to examine temporal and large-scale changes in epibenthic fish species composition. Based on percent species shared among samples, faunal groups (≥10% species shared) consistently reoccurred over time on the shelf-break (ca. 200 m), upper-slope (ca. 300 to 500 m) and upper-to-mid slope (ca. 500 to 1500 m) depths. These similar depth groups also merged when the three studies were pooled together, suggesting that there has been no large-scale temporal change in depth zonation on the upper section of the continental margin. Permutational multivariate analysis of variance (PERMANOVA) also detected no significant species changes on the limited sites and areas that have been revisited across the studies (P>0.05). Based on the ordination of the species shared among samples, species replacement was a continuum along a depth or macrobenthos biomass gradient. Despite the well-known, close, negative relationship between water depth and macrofaunal biomass, the fish species changed more rapidly at depth shallower than 1,000 m, but the rate of change was surprisingly slow at the highest macrofaunal biomass (>100 mg C m(-2)), suggesting that the composition of epibenthic fishes was not altered in response to the extremely high macrofaunal biomass in the upper Mississippi and De Soto Submarine Canyons. An alternative is that the pattern of fish species turnover is related to the decline in macrofaunal biomass, the presumptive prey of the fish, along the depth gradient.

Morphological changes within Florida Bay as a result of sea level rise

Science.gov (United States)

Holmes, C. W.

2011-12-01

Data from Florida Bay indicates that from 10,000 year BP to 6000 BP, the rate of sea level rise averaged about 10 mm/yr. The rate slowed at the end of this period flooding the shallow shelves surrounding the reef platforms of the western Atlantic. The relative flat South Florida shelf, because of its slight tilt to the southwest is an ideal local to assess the effects of this flooding. From 6000 BP to the present, numerous banks were formed within Florida Bay. A morphological model of bank formation based on the sea level oscillations was constructed from analysis of over 120 cores. These cores record sedimentological changes which are correlated to climatic events. In the central bay, the sediment accumulation was controlled by variations in rate of progressive sea-level rise. The Key West sea-level record shows that sea level has been rising incrementally over the last century. Between 1931 and 1950, sea level rose at a rate of 5 mm/yr. After 1950, it remained stable until 1971, when it again began to rise, but at a rate of 3 mm/yr. On the leeward side of mud banks, these variations resulted in shifts in sediment- accumulation rates, with accretion increasing during rising sea level and decreasing during stable periods. Between late 1970 and early 1972, a sharp jump in sea-level rise occurred that was approximately 10 cm higher than the preceding period. This jump coincided with a strongly positive North Atlantic Oscillation (NAO), a la Niña (negative ENSO), and a negative Pacific Decadal Oscillation (PDO). Water driven northward into Florida Bay eroded banks along the northern coastline, increased sediment accumulation in the northern lakes, and increased accretion rates on the banks. In addition to the sedimentological variations in the central portion of the bay, there was significant changes along the northern fringe. Around 1950, the northern fringe of the bay morphed from a fresh water environment to a marine environment. As a result, carbonate production

A regression modeling approach for studying carbonate system variability in the northern Gulf of Alaska

Science.gov (United States)

Evans, Wiley; Mathis, Jeremy T.; Winsor, Peter; Statscewich, Hank; Whitledge, Terry E.

2013-01-01

northern Gulf of Alaska (GOA) shelf experiences carbonate system variability on seasonal and annual time scales, but little information exists to resolve higher frequency variability in this region. To resolve this variability using platforms-of-opportunity, we present multiple linear regression (MLR) models constructed from hydrographic data collected along the Northeast Pacific Global Ocean Ecosystems Dynamics (GLOBEC) Seward Line. The empirical algorithms predict dissolved inorganic carbon (DIC) and total alkalinity (TA) using observations of nitrate (NO3-), temperature, salinity and pressure from the surface to 500 m, with R2s > 0.97 and RMSE values of 11 µmol kg-1 for DIC and 9 µmol kg-1 for TA. We applied these relationships to high-resolution NO3- data sets collected during a novel 20 h glider flight and a GLOBEC mesoscale SeaSoar survey. Results from the glider flight demonstrated time/space along-isopycnal variability of aragonite saturations (Ωarag) associated with a dicothermal layer (a cold near-surface layer found in high latitude oceans) that rivaled changes seen vertically through the thermocline. The SeaSoar survey captured the uplift to aragonite saturation horizon (depth where Ωarag = 1) shoaled to a previously unseen depth in the northern GOA. This work is similar to recent studies aimed at predicting the carbonate system in continental margin settings, albeit demonstrates that a NO3--based approach can be applied to high-latitude data collected from platforms capable of high-frequency measurements.

Structural interpretation of seismic data of Abu Rudeis-Sidri area, Northern Central Gulf of Suez, Egypt

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Hesham Shaker Zahra

2016-12-01

Full Text Available The 2D and 3D seismic data are interpreted to evaluate the subsurface geologic structures in the Abu Rudeis-Sidri area that occupy the northern central part of the Gulf of Suez. The 2D seismic data are used for determination of the structural configurations and the tectonic features which is analyzed through the study of interpretation with the available geologic data, in which the geo-seismic depth maps for the main interesting tops (Kareem, Nukhul, Matulla, Raha and Nubia Formations are represented. Such maps reflect that, the Miocene structure of Abu Rudeis-Sidri area is an asymmetrical NW-SE trending anticlinal feature dissected by a set of NW-SE fault system (clysmic. Added, the Pre-Miocene structure of the studied area is very complex, where the area is of NE dip and affected by severe faulting through varying stratigraphic levels.

Anti-cyclonic circulation driven by the estuarine circulation in a gulf type ROFI

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Fujiwara, T.; Sanford, L. P.; Nakatsuji, K.; Sugiyama, Y.

1997-08-01

Baroclinic residual circulation processes are examined in gulf type Regions Of Freshwater Influence (ROFIs), which have large rivers discharging into a rounded head wider than the Rossby internal deformation radius. Theoretical and observational investigations concentrate on Ise Bay, Japan, with supporting data from Osaka Bay and Tokyo Bay. Simplified analytical solutions are derived to describe the primary features of the circulation. Three dimensional residual current data collected using moored current meters and shipboard acoustic doppler current profilers (ADCPs), satellite imagery and density structure data observed using STDs, are presented for comparison to the theoretical predictions. There are three key points to understanding the resulting circulation in gulf type ROFIs. First, there are likely to be three distinct water masses: the river plume, a brackish upper layer, and a higher salinity lower layer. Second, baroclinic processes in gulf type ROFIs are influenced by the Earth's rotation at first order. Residual currents are quasi-geostrophic and potential vorticity is approximately conserved. Third, the combined effects of a classical longitudinal estuarine circulation and the Earth's rotation are both necessary to produce the resulting circulation. Anti-cyclonic vorticity is generated in the upper layer by the horizontal divergence associated with upward entrainment, which is part of the estuarine circulation. The interaction between anti-cyclonic vorticity and horizontal divergence results in two regions of qualitatively different circulation, with gyre-like circulation near the bay head and uniformly seaward anti-cyclonicly sheared flow further towards the mouth. The stagnation point separating the two regions is closer to (further away from) the bay head for stronger (weaker) horizontal divergence, respectively. The vorticity and spin-up time of this circulation are-(ƒ-ω 1)/2 and h/2w 0, respectively, where ƒ is the Coriolis parameter, ω 1 is

Numerical Simulation of Salinity and Dissolved Oxygen at Perdido Bay and Adjacent Coastal Ocean

Science.gov (United States)

Environmental Fluid Dynamic Code (EFDC), a numerical estuarine and coastal ocean circulation hydrodynamic model, was used to simulate the distribution of the salinity, temperature, nutrients and dissolved oxygen (DO) in Perdido Bay and adjacent Gulf of Mexico. External forcing fa...

Polychlorinated biphenyl (PCB) contamination in Galveston Bay, Texas: Comparing concentrations and profiles in sediments, passive samplers, and fish.

Science.gov (United States)

Oziolor, Elias M; Apell, Jennifer N; Winfield, Zach C; Back, Jeffrey A; Usenko, Sascha; Matson, Cole W

2018-05-01

The industrialized portion of the Houston Ship Channel (HSC) is heavily contaminated with anthropogenic contaminants, most prominent of which are the polychlorinated biphenyls (PCBs). This contamination has driven adaptive evolution in a keystone species for Galveston Bay, the Gulf killifish (Fundulus grandis). We investigated the geographical extent of PCB impacts by sampling 12 sites, ranging from the heavily industrialized upper portion of the HSC to Galveston Island. At each site, PCB concentrations and profiles were determined in three environmental compartments: sediment, water (polyethylene passive samplers), and fish tissue (resident Gulf killifish). We observed a steep gradient of PCB contamination, ranging from 4.00 to 100,000 ng/g organic carbon in sediment, 290-110,000 ng/g lipid in fish, and 4.5-2300 ng/g polyethylene in passive samplers. The PCB congener profiles in Gulf killifish at the most heavily contaminated sites were shifted toward the higher chlorinated PCBs and were highly similar to the sediment contamination profiles. In addition, while magnitude of total PCB concentrations in sediment and total fish contamination levels were highly correlated between sites, the relative PCB congener profiles in fish and passive samplers were more alike. This strong correlation, along with a lack of dependency of biota-sediment accumulation factors with total contamination rates, confirm the likely non-migratory nature of Gulf killifish and suggest their contamination levels are a good site-specific indicator of contamination in the Galveston Bay area. The spatial gradient of PCB contamination in Galveston Bay was evident in all three matrices studied and was observed effectively using Gulf killifish contamination as an environmentally relevant bioindicator of localized contamination in this environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thermohaline circulation in the Gulf of California

Science.gov (United States)

Bray, N. A.

1988-05-01

The Gulf of California, a narrow, semienclosed sea, is the only evaporative basin of the Pacific Ocean. As a result of evaporative forcing, salinities in the gulf are 1 to 2 ‰ higher than in the adjacent Pacific at the same latitude. This paper examines the thermohaline structure of the gulf and the means by which thermohaline exchange between the Pacific and the gulf occurs, over time scales of months to years. In addition to evaporative forcing, air-sea heat fluxes and momentum fluxes are important to thermohaline circulation in the gulf. From observations presented here, it appears that the gulf gains heat from the atmosphere on an annual average, unlike the Mediterranean and Red seas, which have comparable evaporative forcing. As a result, outflow from the gulf tends to be less dense than inflow from the Pacific. Winds over the gulf change direction with season, blowing northward in summer and southward in winter. This same seasonal pattern appears in near-surface transports averaged across the gulf. The thermohaline circulation, then, consists of outflow mostly between about 50 m and 250 m, inflow mostly between 250 m and 500 m, and a surface layer in which the direction of transport changes with seasonal changes in the large-scale winds. Using hydrographic observations from a section across the central gulf, total transport in or out of the northern gulf is estimated to be 0.9 Sv, heat gain from the atmosphere is estimated to be 20 to 50 W m-2, and evaporation is estimated to be 0.95 m yr-1. These estimates are annual averages, based on cruises from several years. Seasonal variations in thermohaline structure in the gulf are also examined and found to dominate the variance in temperature and density in the top 500 m of the water column. Salinity has little seasonal variability but does exhibit more horizontal variablility than temperature or density. Major year-to-year variations in thermohaline structure may be attributable to El Niño-Southern Oscillation

The effect of radioactive waste storage in Andreev Bay on contamination of the Barents Sea ecosystem

Science.gov (United States)

Matishov, G. G.; Ilyin, G. V.; Usyagina, I. S.; Moiseev, D. V.; Dahle, Salve; Kasatkina, N. E.; Valuyskaya, D. A.

2017-02-01

The effect of temporary radioactive waste storage on the ecological status of the sea and biota in the littoral of Andreev and Malaya Andreev bays and near the shore of Motovskii Gulf (including the mouth part of the Zapadnaya Litsa Bay) was analyzed. The littoral sediments contaminated by the 137Cs, 90Sr, 238Pu, and 239,240Pu isotopes are located in the zones of constant groundwater discharge on the shores of Andreev and Malaya Andreev bays. The littoral slopes and bottom depressions of the bays accumulate finely dispersed terrigenous material and 137Cs. The investigations have shown that the storage does not exert a significant adverse effect on the radioactive conditions and the status of the sea ecosystems beyond Andreev Bay.

Phosphorus, nitrogen and chlorophyll-a are significant factors controlling ciliate communities in summer in the northern Beibu Gulf, South China Sea.

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Yibo Wang

Full Text Available Ciliates (protozoa are ubiquitous components of plankton community and play important roles in aquatic ecosystems in regards of their abundance, biomass, diversity and energy turnover. Based on the stratified samples collected from the northern Beibu Gulf in August 2011, species composition, abundance, biomass, diversity and spatial pattern of planktonic ciliates were studied. Furthermore the main environmental factors controlling ciliate communities were determined. A total of 101 species belonging to 44 genera and 7 orders (i.e., Oligotrichida, Haptorida, Euplotida, Sessilida, Pleurostomatida, Scuticociliatida and Tintinnida were identified. The variation of ciliate communities was significant at horizontal level, but that was not at vertical level. Based on cluster analysis, ciliate communities were divided into three main groups. Redundancy analysis (RDA revealed that Group A, existing in the waters with higher concentration of phosphorus and nitrogen, was dominated by Tintinnidium primitivum. Group B in the waters with lower temperature and chlorophyll-a concentration, was dominated by Leegaardiella ovalis. Group C, existing in the waters with higher temperature and chlorophyll-a concentration, was dominated by large Strombidium spp. and Mesodinium rubrum. Combining multiple analytic methods, our results strongly supported that phosphorus, nitrogen and chlorophyll-a were the most significant factors affecting the ciliate communities in the northern Beibu Gulf in summer. Concentration of phosphorus and nitrogen primarily influenced ciliate biomass, implying a potential impact of eutrophication on ciliate growth. The correlation with chlorophyll-a concentration, on one hand indicate the response of ciliates to the food availability, and on the other hand, the ciliates containing chloroplasts or endosymbionts may contribute greatly to the chlorophyll-a.

Detection of Induced Seismicity Due to Oil and Gas Extraction in the Northern Gulf of Mexico, USA

Science.gov (United States)

Fadugba, O. I.; Ebel, J.

2014-12-01

Drilling operations and extraction of oil and gas (O&G) may lead to subsurface slumping or compression of sediments due to reduced vertical principal stress which may lead to small earthquakes at the drilling site. O&G extraction is common in the northern Gulf of Mexico (NGM) and only thirty-five earthquakes of magnitudes between 2.3 and 6.0 have been recorded in the area from 1974 to the present. The purpose of this research is to detect more earthquakes using stacks of seismic data from the EarthScope Transportable USArray (TA) from 2011 to 2013, and determine the spatiotemporal relationship between the detected earthquakes and O&G extraction. TA waveform records were retrieved from IRIS database and a narrow bandpass filter of 1 - 2 Hz was applied to remove background and high frequency noises and focus on the low energy part of the signal. The seismic record at all stations was plotted vertically with respect to distance from the Gulf. An Automatic Gain Control (AGC) using Root Mean Square was applied to boost the signals at farther stations. More than 1500 events have been detected, including teleseisms and local blasts from the area, especially from the three Walter Minerals coal mines in Alabama. No offshore earthquakes have been detected in the data, although data processing is still ongoing. Therefore, any earthquake activity, if present, associated with the offshore oil and gas production must be at a magnitude below the detection threshold of the algorithm.

Northern Gulf 1 Arc-second MHW Coast Digital Elevation Model

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National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico....

Biogenic origin of coalbed gas in the northern Gulf of Mexico Coastal Plain, U.S.A

Science.gov (United States)

Warwick, Peter D.; Breland, F. Clayton; Hackley, Paul C.

2008-01-01

New coal-gas exploration and production in northern Louisiana and south-central Mississippi, Gulf of Mexico Basin, is focused on the Wilcox Group (Paleocene–Eocene), where the depth to targeted subbituminous C to high volatile C bituminous coal beds ranges from 300 to 1680 m, and individual coal beds have a maximum thickness of about 6 m. Total gas content (generally excluding residual gas) of the coal beds ranges from less than 0.37 cm3/g (as-analyzed or raw basis; 1.2 cm3/g, dry, ash free basis, daf) at depths less than 400 m, to greater than 7.3 cm3/g (as-analyzed basis; 8.76 cm3/g, daf) in deeper (> 1,500 m) parts of the basin. About 20 Wilcox coal-gas wells in northern Louisiana produce from 200 to 6485 m3 of gas/day and cumulative gas production from these wells is approximately 25 million m3 (as of December, 2006). U.S. Geological Survey assessment of undiscovered, technically recoverable gas resources in the Gulf of Mexico Coastal Plain, including northern and south-central Mississippi, indicates that coal beds of the Wilcox Group contain an estimated mean total 109.3 million m3 (3.86 trillion ft3) of producible natural gas.To determine the origin of the Wilcox Group coal gases in northern Louisiana, samples of gas, water, and oil were collected from Wilcox coal and sandstone reservoirs and from under- and overlying Late Cretaceous and Eocene carbonate and sandstone reservoirs. Isotopic data from Wilcox coal-gas samples have an average δ13CCH4 value of − 62.6‰ VPDB (relative to Vienna Peedee Belemnite) and an average δDCH4 value of − 199.9‰ VSMOW (relative to Vienna Standard Mean Ocean Water). Values of δ13CCO2 range from − 25.4 to 3.42‰ VPDB. Produced Wilcox saline water collected from oil, conventional gas, and coalbed gas wells have δDH2O values that range from − 27.3 to − 18.0‰ VSMOW. These data suggest that the coal gases primarily are generated in saline formation water by bacterial reduction of CO2

Biogenic origin of coalbed gas in the northern Gulf of Mexico Coastal Plain, U.S.A.

Energy Technology Data Exchange (ETDEWEB)

Warwick, Peter D.; Hackley, Paul C. [U.S. Geological Survey, 956 National Center, Reston, VA 20192 (United States); Breland, F. Clayton Jr. [Louisiana Department of Natural Resources, 617 North 3rd Street, Baton Rouge, LA 70802 (United States)

2008-10-02

New coal-gas exploration and production in northern Louisiana and south-central Mississippi, Gulf of Mexico Basin, is focused on the Wilcox Group (Paleocene-Eocene), where the depth to targeted subbituminous C to high volatile C bituminous coal beds ranges from 300 to 1680 m, and individual coal beds have a maximum thickness of about 6 m. Total gas content (generally excluding residual gas) of the coal beds ranges from less than 0.37 cm{sup 3}/g (as-analyzed or raw basis; 1.2 cm{sup 3}/g, dry, ash free basis, daf) at depths less than 400 m, to greater than 7.3 cm{sup 3}/g (as-analyzed basis; 8.76 cm{sup 3}/g, daf) in deeper (> 1,500 m) parts of the basin. About 20 Wilcox coal-gas wells in northern Louisiana produce from 200 to 6485 m{sup 3} of gas/day and cumulative gas production from these wells is approximately 25 million m{sup 3} (as of December, 2006). U.S. Geological Survey assessment of undiscovered, technically recoverable gas resources in the Gulf of Mexico Coastal Plain, including northern and south-central Mississippi, indicates that coal beds of the Wilcox Group contain an estimated mean total 109.3 million m{sup 3} (3.86 trillion ft{sup 3}) of producible natural gas. To determine the origin of the Wilcox Group coal gases in northern Louisiana, samples of gas, water, and oil were collected from Wilcox coal and sandstone reservoirs and from under- and overlying Late Cretaceous and Eocene carbonate and sandstone reservoirs. Isotopic data from Wilcox coal-gas samples have an average {delta}{sup 13}C{sub CH4} value of - 62.6 permille VPDB (relative to Vienna Peedee Belemnite) and an average {delta}D{sub CH4} value of - 199.9 permille VSMOW (relative to Vienna Standard Mean Ocean Water). Values of {delta}{sup 13}C{sub CO2} range from - 25.4 to 3.42 permille VPDB. Produced Wilcox saline water collected from oil, conventional gas, and coalbed gas wells have {delta}D{sub H2O} values that range from - 27.3 to - 18.0 permille VSMOW. These data suggest that the

Wind driven nutrient and subsurface chlorophyll-a enhancement in the Bay of La Paz, Gulf of California

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Coria-Monter, Erik; Monreal-Gómez, María Adela; Salas de León, David Alberto; Durán-Campos, Elizabeth; Merino-Ibarra, Martín

2017-09-01

Nutrient and chlorophyll-a distributions in the Bay of La Paz, Gulf of California, Mexico were analyzed during the late spring of 2004 to assess their relations to hydrography and circulation patterns. The results show the presence of both Gulf of California Water and Subtropical Subsurface Water. Water circulation was dominated by wind stress driven cyclonic circulation along f / H contours (f is planetary vorticity and H is depth), and upwelling resulting from the divergence shows a vertical velocity of ∼0.4 m d-1. Nutrient concentrations were higher in the center of the cyclonic pattern, where a rise in the nutricline contributed nutrients to the euphotic layer as a result of Ekman pumping. The vertical section showed the presence of a chlorophyll-a maximum at the thermocline shoaling to a depth of only 12 m. Along the surface, two peaks of chlorophyll-a were observed, one at Boca Grande and another off San Juan de la Costa, associated with upwelling and mixing derived from current interactions with abrupt topographies. The chlorophyll-a maximum increased from 0.8 mg m-3 in the external part of the cyclonic pattern to 2.0 mg m-3 in its center. The vertically integrated chlorophyll-a concentrations followed a similar pattern, rising from 10 to 20 mg m-2 and reaching their highest values in the center of the cyclonic circulation pattern. A schematic model was developed to describe processes that occur in late spring: the wind stress driven cyclonic structure promotes upward nutrient flux, which in turn drives an enhancement of chlorophyll-a. Upwelling was found to be the main mechanism of fertilization responsible for the enhancement of productivity levels by means of nutrient transport into the euphotic zone during spring. Other chlorophyll enhancement areas point to the occurrence of additional fertilization processes that may derive from interactions between cyclonic circulation patterns and the topography off of San Juan de la Costa, where phosphate mining

A bottom-driven mechanism for distributed faulting: Insights from the Gulf of California Rift

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Persaud, P.; Tan, E.; Choi, E.; Contreras, J.; Lavier, L. L.

2017-12-01

The Gulf of California is a young oblique rift that displays a variation in rifting style along strike. Despite the rapid localization of strain in the Gulf at 6 Ma, the northern rift segment has the characteristics of a wide rift, with broadly distributed extensional strain and small gradients in topography and crustal thinning. Observations of active faulting in the continent-ocean transition of the Northern Gulf show multiple oblique-slip faults distributed in a 200 x 70 km2area developed some time after a westward relocation of the plate boundary at 2 Ma. In contrast, north and south of this broad pull-apart structure, major transform faults accommodate Pacific-North America plate motion. Here we propose that the mechanism for distributed brittle deformation results from the boundary conditions present in the Northern Gulf, where basal shear is distributed between the Cerro Prieto strike-slip fault (southernmost fault of the San Andreas fault system) and the Ballenas Transform fault. We hypothesize that in oblique-extensional settings whether deformation is partitioned in a few dip-slip and strike-slip faults, or in numerous oblique-slip faults may depend on (1) bottom-driven, distributed extension and shear deformation of the lower crust or upper mantle, and (2) the rift obliquity. To test this idea, we explore the effects of bottom-driven shear on the deformation of a brittle elastic-plastic layer with pseudo-three dimensional numerical models that include side forces. Strain localization results when the basal shear is a step-function while oblique-slip on numerous faults dominates when basal shear is distributed. We further investigate how the style of faulting varies with obliquity and demonstrate that the style of faulting observed in the Northern Gulf of California is reproduced in models with an obliquity of 0.7 and distributed basal shear boundary conditions, consistent with the interpreted obliquity and boundary conditions of the study area. Our

Towards a record of Holocene tsunami and storms for northern Hawke's Bay, New Zealand

International Nuclear Information System (INIS)

Cochran, U.A.; Berryman, K.R.; Mildenhall, D.C.; Hayward, B.W.; Southall, K.; Hollis, C.J.

2005-01-01

Eleven sand layers occur within Holocene low-energy estuarine and marginal marine sequences of blue-grey silty clay at two sites on the coastal plain between Wairoa and Mahia Peninsula, northern Hawke's Bay, New Zealand. The sedimentology and fossil assemblages of these layers are consistent with deposition by high-energy influxes to the sites. Three influxes are terrestrial in nature and are thought to represent alluvial flood events. All other sand layers are marine derived and are likely to be the result of storm surges or tsunami. Tsunami inundation is favoured for two sand layers that occur in association with evidence for sudden subsidence at c. 6300 and c. 4800 yr BP. The c. 6300 yr inundation also coincides with previously identified evidence for a tsunami at a site 10 km westwards along the coast. Further investigation is required to distinguish between tsunami and storm surge deposition for the remaining six layers. (author). 50 refs., 4 figs., 2 tabs

Horizontal distribution of near-inertial waves in the western Gulf of Mexico: Eulerian vs Lagrangian.

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Pallas Sanz, E.; García-Carrillo, P.; Garcia Gomez, B. I.; Lilly, J. M.; Perez-Brunius, P.

2016-02-01

The time-average horizontal distribution of the near-inertial waves (NIWs) on the western Gulf of Mexico (GoM) is investigated using horizontal velocity data obtained from Lagrangian trajectories of 200 surface drifters drogued at 50m and deployed between September 2008 and September 2012. Preliminary results suggest maximum time-averaged near-inertial circle radius of 2.6km located in the southern Campeche bay near [22N,95W]; implying an inertial velocity of about 0.14m/s. Similar conclusions are delineated using horizontal velocity data obtained from 21 moorings deployed in the western GoM during the same time period. Maximum near-inertial kinetic energy and clockwise spectral energy is found in the mooring LNK3500 located at 21.850N and 94.028W. Maximum inertial circles measured with mooring data, however, are of about 1.6km leading to inertial currents of 0.087m/s, approximately a 40% smaller. This discrepancy seems to be due to the different depth level of the measurements and the bandwidth used to extract the near-inertial oscillations from the total flow. The time-average horizontal distributions of wind work computed from Lagrangian and Eulerian data are compared and they are not consistent with the time-averaged NIW field. The differences are not well understood but we speculate they may be due to the different time scales of wind fluctuations in the northwestern GoM compared to those observed in the Bay of Campeche, together with the change of sign of the background vorticity in the region; being negative (anticyclonic) in the northern GoM and positive (cyclonic) in the Bay of Campeche.

Archaeal enrichment in the hypoxic zone in the northern Gulf of Mexico.

Science.gov (United States)

Gillies, Lauren E; Thrash, J Cameron; deRada, Sergio; Rabalais, Nancy N; Mason, Olivia U

2015-10-01

Areas of low oxygen have spread exponentially over the past 40 years, and are cited as a key stressor on coastal ecosystems. The world's second largest coastal hypoxic (≤ 2 mg of O2 l(-1)) zone occurs annually in the northern Gulf of Mexico. The net effect of hypoxia is the diversion of energy flow away from higher trophic levels to microorganisms. This energy shunt is consequential to the overall productivity of hypoxic water masses and the ecosystem as a whole. In this study, water column samples were collected at 39 sites in the nGOM, 21 of which were hypoxic. Analysis of the microbial community along a hypoxic to oxic dissolved oxygen gradient revealed that the relative abundance (iTag) of Thaumarchaeota species 16S rRNA genes (> 40% of the microbial community in some hypoxic samples), the absolute abundance (quantitative polymerase chain reaction; qPCR) of Thaumarchaeota 16S rRNA genes and archaeal ammonia-monooxygenase gene copy number (qPCR) were significantly higher in hypoxic samples. Spatial interpolation of the microbial and chemical data revealed a continuous, shelfwide band of low dissolved oxygen waters that were dominated by Thaumarchaeota (and Euryarchaeota), amoA genes and high concentrations of phosphate in the nGOM, thus implicating physicochemical forcing on microbial abundance. © 2015 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Use of Geographic Information Systems to examine cumulative impacts of development on Mobile Bay, AL and Galveston Bay, TX

International Nuclear Information System (INIS)

Rosigno, P.F.; McNiff, M.E.; Watzin, M.C.; Ji, W.

1993-01-01

Databases from Mobile Bay, Alabama and Galveston Bay, Texas were compiled using ARC/INFO Geographic Information Systems (GIS) to examine the cumulative impacts from urbanization and industrialization on these two Gulf of Mexico estuaries. The databases included information on wetland habitats, pollution sources, metal contamination, bird-nesting sites, and oyster reefs, among others. A series of maps were used to represent the impacts within and between each ecosystem. These two estuaries share many similarities in the types of developmental pressures that each experience. However, difference in the magnitude of industrial activity, pollution loading, and urban growth coupled with distinct hydrodynamic and geochemical differences in sediment mineralogy, freshwater inflows and salinity regimens results in differing responses. With growing human population and extensive oil and gas development, the demands on Galveston Bay are quite different than those placed on Mobile Bay which has lower growth and less extensive oil and gas infrastructure. Mobile Bay tends to retain whatever contamination enters into the system because of the high levels of clay and organic carbon found in its sediment. Some of these chemicals bioaccumulate, posing an extra risk to natural resources. Geographic Information Systems provide natural resource managers with the technology to manage complex databases. The analytical and mapping capabilities of GIS can be used to consider cumulative effects in a regional context and to develop plans to protect ecologically sensitive areas

Integrating terrestrial LiDAR and stereo photogrammetry to map the Tolay lakebed in northern San Francisco Bay

Science.gov (United States)

Woo, Isa; Storesund,; Takekawa, John Y.; Gardiner, Rachel J.; Ehret,

2009-01-01

The Tolay Creek Watershed drains approximately 3,520 ha along the northern edge of San Francisco Bay. Surrounded by a mosaic of open space conservation easements and public wildlife areas, it is one of the only watersheds in this urbanized estuary that is protected from its headwaters to the bay. Tolay Lake is a seasonal, spring-fed lake found in the upper watershed that historically extended over 120 ha. Although the lakebed was farmed since the early 1860s, the majority of the lakebed was recently acquired by the Sonoma County Regional Parks Department to restore its natural habitat values. As part of the restoration planning process, we produced a digital elevation model (DEM) of the historic extent of Tolay Lake by integrating terrestrial LiDAR (light detection and ranging) and stereo photogrammetry datasets, and real-time kinematic (RTK) global positioning system (GPS) surveys. We integrated the data, generated a DEM of the lakebed and upland areas, and analyzed errors. The accuracy of the composite DEM was verified using spot elevations obtained from the RTK GPS. Thus, we found that by combining photogrammetry, terrestrial LiDAR, and RTK GPS, we created an accurate baseline elevation map to use in watershed restoration planning and design.

Environmental assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Santander Bay, Northern Spain.

Science.gov (United States)

Viguri, J; Verde, J; Irabien, A

2002-07-01

Samples of intertidal surface sediments (0-2 cm) were collected in 17 stations of the Santander Bay, Cantabric Sea, Northern Spain. The concentrations of polycyclic aromatic hydrocarbons (PAHs), 16, were analysed by HPLC and MS detection. Surface sediments show a good linear correlation among the parameters of the experimental organic matter evaluation, where total carbon (TC) and loss on ignition (LOI) are approximately 2.5 and 5 times total organic carbon (TOC). A wide range of TOC from 0.08% to 4.1%, and a broad distribution of the sum of sigma16PAHs, from 0.02 to 344.6 microg/g d.w., which can be correlated by an exponential equation to the TOC, has been identified. A qualitative relationship may be established between the industrial input along the rivers and the concentration of sigma6PAHs in the sediments of the estuaries: Boo estuary (8404-4631 microg/g OC), Solia-San Salvador estuaries (305-113 microg/g OC) and Cubas estuary (31-32 microg/g OC). This work shows a dramatic change in the spatial distribution in the concentration of PAHs of intertidal surface sediments. The left edge of the Bay has the main traffic around the city and the major source of PAHs is from combustion processes and estuarine inputs, leading to medium values of PAHs in the sediments; the right edge of the Bay has much lesser anthropogenic activities leading to lower values of PAHs in sediments. The distribution of individual PAHs in sediments varies widely depending on their structure and molecular weight; the 4-6 ring aromatics predominate in polluted sediments due to their higher persistence. The isomer ratio does not allow any clear identification of the PAHs origin. Environmental evaluation according to Dutch guidelines and consensus sediment quality guidelines based on ecotoxicological data leads to the same conclusion, sediments in the Santander Bay show a very different environmental quality depending on the spatial position from heavily polluted/medium effects to non

Detection of induced seismicity due to oil and gas extraction in the northern Gulf of Mexico, USA

Science.gov (United States)

Fadugba, Oluwaseun Idowu

Drilling operations and extraction of oil and gas (O&G) may lead to subsurface slumping or compression of sediments due to reduced vertical principal stress which may lead to small earthquakes at the drilling site. O&G extraction is common in the northern Gulf of Mexico (NGM) and only thirty-five earthquakes of magnitudes between 2.3 and 6.0 have been recorded in the area from 1974 to the present. The purpose of this research is to detect more earthquakes using stacks of seismic data from the Transportable USArray (TA) from 2011 to 2013, and determine the spatiotemporal relationship between the detected earthquakes and O&G extraction. Five new small offshore earthquakes, that may be associated with the offshore O&G production, have been detected in the data. Spatial correlation of the epicenters with offshore drilling sites shows that the earthquakes may be due to the O&G extraction.

Policing Iranian Sanctions: Trade, Identity, and Smuggling Networks in the Arabian Gulf

Science.gov (United States)

2013-03-01

Kegan Paul International, 1994), 9–10. 22 A.W. Stiffe, “Ancient Trading Centres of the Persian Gulf: VII Bahrain,” The Geographical Journal 18, no... Kegan Paul International, 1994. Al Naboodah, H.M. “The Commercial Activity of Bahrain and Oman in the Early Middle Ages.” Proceedings of the...Byman, Daniel and Jerrold Green . Political Violence and Stability in the States of the Northern Persian Gulf. California: RAND, 1999. Castles

Analysis of Suspended-Sediment Dynamics in Gulf of Mexico Estuaries Using MODIS/Terra 250-m Imagery

Science.gov (United States)

McCarthy, M. J.; Otis, D. B.; Muller-Karger, F. E.; Mendez-Lazaro, P.; Chen, F. R.

2016-02-01

Suspended sediments in coastal ecosystems reduce light penetration, degrade water quality, and inhibit primary production. In this study, a 15-year Moderate Resolution Imaging Spectroradiometer (MODIS/Terra) turbidity time-series was developed for use in the estuaries of the Gulf of Mexico (GOM). Remote-sensing reflectance (Rrs) at 645 nm and 250-m resolution was validated with in-situ turbidity measurements in these estuaries: Coastal Bend Bays (TX), Galveston Bay (TX), Barataria and Terrebonne Bays (LA), Mobile Bay (AL), Tampa Bay (FL), Sarasota Bay (FL), and Charlotte Harbor (FL). Mean values of turbidity over the time-series ranged from 2.5 NTU to over 10 NTU. Turbidity patterns exhibited seasonal cycles with peak values generally found during spring months, although there is considerable variability in the timing of peak turbidity. Episodes of elevated turbidity ranged from 6 episodes in Galveston Bay to 15 in Mobile Bay. The spatial extent of elevated turbidity within estuaries, frequency and duration of turbidity events, and potential driving factors behind episodes of elevated turbidity were also examined.

Seasonal and spatial variation in the abundance and size distribution of fishes associated with a petroleum platform in the northern Gulf of Mexico

International Nuclear Information System (INIS)

Stanley, D.R.; Wilson, C.A.

1997-01-01

Currently, there are more than 4,000 petroleum platforms in the Gulf of Mexico. These platforms act as artificial reefs, providing a habitat that can increase the growth and survival of fish, giving shelter and protection from predators and spawning substrate. The density, target strength, and species composition of fishes associated with a petroleum platform in the northern Gulf of Mexico were measured using stationary dual-beam hydroacoustic and visual point count surveys. Monthly measurements were made from January 1991 through May 1992. Target strengths varied greatly depending on the side of the platform, month, and east and north current vectors. Density and target strength did not change over 24 hour periods or with water temperature. Fish densities were greatest adjacent to the platform and decreased substantially beyond 16 metres. About 1,990 to 28,100 fish, including 19 species, were associated with the platform depending on the month. These results suggest that fishes associated with petroleum platforms behave in a manner similar to that of fishes in coral reef habitats. 60 refs., 4 tabs., 5 figs

First record of two hard coral species (Faviidae and Siderastreidae from Qeshm Island (Persian Gulf, Iran

Directory of Open Access Journals (Sweden)

MOHAMMAD SHARIF RANJBAR

2010-01-01

Full Text Available Moradi M, Kamrani E, Shokri MR, Ranjbar MS, Hesni MA (2009 First record of two hard coral species (Faviidae and Siderastreidae from Qeshm Island (Persian Gulf, Iran. Nusantara Bioscience 2: 34-37. Two species of hard corals including Cyphastrea chalcidicum (Forskal 1775 (Faviidae and Coscinaraea monile (Forskal 1775 (Siderastreidae were collected from the south of Qeshm Island (Persian Gulf, Iran in the late of 2008. These species were previously reported from southern Persian Gulf, Gulf of Aden, Southeast Africa and Indo-Pacific. The literature review on the distribution of these two species revealed that these species were firstly recorded from the Persian Gulf. These findings further emphasize the high diversity of coral fauna in the Iranian waters of the northern Persian Gulf.

Exposure of northern leopard frogs in the Green Bay ecosystem to polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans is measured by direct chemistry but not hepatic ethoxyresorufin-O-deethylase activity

Energy Technology Data Exchange (ETDEWEB)

Huang, Y.W.; Karasov, W.H.; Patnode, K.A.; Jefcoate, C.R.

1999-10-01

The authors measured concentrations of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) in northern leopard frogs collected from the Green Bay ecosystem and explored the catalytic activity of hepatic cytochrome P450-associated monooxygenase (P450 enzyme) as a biomarker for exposure to aryl hydrocarbon receptor (AhR) agonists. The two hypotheses tested were PCH concentrations in northern leopard frogs would be positively correlated with sediment polychlorinated hydrocarbon (PCH) levels in wetland habitats along a contamination gradient and hepatic ethoxyresorufin-O-deethylase (EROD) activity of northern leopard frogs, which is presumably mediated by aryl hydrocarbon receptor (AhR), would be positively correlated with PCH concentrations in frog carcasses from different collection sites. In 1994 and 1995, frogs from seven sites along the lower Fox River and Green Bay, USA, were assayed for hepatic EROD activities and whole carcass concentrations of PCBs, PCDDs, and PCDFs. Tissue total PCB concentrations ranging from 3 to 154 ng/g were significantly correlated with sediment PCB levels. Only one PCDD and two PCDFs at concentrations of 6 to 8 pg/g were found in the frogs collected with frog body weight and was similar among sites except for Peter's Marsh. No significant correlation was found between EROD activity and carcass PCB concentration. This result was consistent with the fact that the frogs collected from the Green Bay ecosystem had relatively low PCB concentrations compared with what was required for induction in the laboratory.

Enhanced particle fluxes in Bay of Bengal inducEd. by injection of freshwater

Digital Repository Service at National Institute of Oceanography (India)

Ittekkot, V.; Nair, R.R.; Honjo, S.; Ramaswamy, V.; Bartsch, M.; Manganini, S.J.; Desai, B.N.

deployed three sediment-trap moorings (two traps in each mooring) in the northern, central and southern parts of the Bay of Bengal, respectively. The Bay of Bengal is suitable for such a study, because some of the world's largest rivers supply pulses...

Spatial distribution and mobility of organic carbon (POC and DOC) in a coastal Mediterranean environment (Saronikos Gulf, Greece) during 2007-2009 period.

Science.gov (United States)

Evangeliou, Nikolaos; Florou, Heleny

2013-08-01

Particulate (POC) and dissolved organic carbon (DOC) is an important parameter for the pollution assessment of coastal marine systems, especially those affected by anthropogenic, domestic, and industrial activities. In the present paper, a similar marine system (Saronikos Gulf) located in the west-central Aegean Sea (eastern Mediterranean Sea) was examined, in terms of the temporal and spatial distribution of organic carbon (POC and DOC), with respect to marine sources and pathways. POC was maximum in winter in the Saronikos Gulf, due to the bloom of phytoplankton, whereas in the Elefsis Bay (located in the north side of the Saronikos Gulf) in summer, since phytoplankton grazes in the Bay in the end of summer (except for winter). Approximately 60 % of the bulk DOC of the water column was estimated as non-refractory (labile and semi-labile), due to the major anthropogenic, domestic, and industrial effects of the region and the shallow depths. The spatial distribution of POC and DOC mainly affects the northeastern section of the Gulf, since that region has been accepted major organic discharges for a long time period, in connection to the relatively long renewal times of its waters.

Environmental and economic assessment of discharges from Gulf of Mexico Region oil and gas operation. Quarterly technical progress report, 1 October--31 December 1994

International Nuclear Information System (INIS)

Gettleson, D.A.

1995-01-01

Task 3 (Environmental Field Sampling and Analysis of NORM, Heavy Metals, and Organics) work included analyses of samples. Task 4 (Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas) activities involved the continued analyses of samples and field sampling at Bay de Chene. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gulf of Mexico Region) activities included preparing a draft final report. Task 6 (Synthesis of Gulf of Mexico Seafood Consumption and Use Patterns) work also involved preparing a draft final report. Task 7 (Technology Transfer Plan) activities included a presentation at the Minerals Management Service Information Transfer Meeting for the Gulf of Mexico OCS Region. Task 8 (Project Management and Deliverables) activities involved the submission of the necessary reports and routine management

Coastal dynamics of Garabogazköl bay of Caspian Sea

Science.gov (United States)

Kurbanov, Redzhep

2016-04-01

Garabogazköl is extremely interesting object for the study of coastal evolution and Caspian sea paleogeography. Bay plays an important role in evolution of the Caspian basin, as a major area of permanent loss of sea water, the volume of which varies in different years from 17 to 23 km3/year, averaging about 20.3 km3/year. Termination of runoff into the bay would provide annual Caspian Sea level rise of about 3 cm. Despite the large-scale research of the coast of the Caspian Sea during the Soviet era, Garabogazköl was generally poorly studied, mostly describing sedimentation patterns of salt deposits (associated with the production of sulfates). The basis of our study was the materials of remote sensing (satellite imagery), supported by field research, description of geomorphological structure of coasts. As known, the Caspian Sea level was at the lowest elevations from 1970 to 1985, ranging from -28.6 to -29.01 m. The creation of the dam in 1980 completely blocked Caspian water inflow into the Gulf, resulting even more drastic reduction in its area, which decreased by 3 times (from 18 to 6 thousand. km2), with depth less than 50 cm. In mid-1992, when the level of the Caspian Sea has risen by more than 2 meters over the level of 1978, the dam was destroyed. The obtained data allowed characterizing the peculiarities of the coast of the Gulf in these conditions. During the start of the coastal retreat first appeared drained relatively shallow northern and western parts. During this period the processes of accumulation were predominate. There was the deposition of thick (up to 1 m) salt horizon. Dominating wind-surge processes resulted relatively smoothed surface, filling rugged topography by terrigenous material and salt. After the explosion of the dam in 1992, the bay was quickly filled with water and in the next 3-4 years is completely covered the Gara-Bogaz depression. In general, a high stability of the coastline of the Gulf observed through analysis of the last

Lessons learned using water quality models to develop numeric nutrient criteria for a Gulf coast estuary

Science.gov (United States)

Pensacola Bay is a shallow, mesotrophic estuary located in the north-central coast of the Gulf of Mexico, US. In November 2012, the US Environmental Protection Agency (US EPA) proposed numeric total nitrogen (TN), total phosphorus (TP), and chlorophyll-a (chl-a) water quality cr...

Ecology of selected marine communities in Glacier Bay: Zooplankton, forage fish, seabirds and marine mammals

Science.gov (United States)

Robards, Martin D.; Drew, Gary S.; Piatt, John F.; Anson, Jennifer Marie; Abookire, Alisa A.; Bodkin, James L.; Hooge, Philip N.; Speckman, Suzann G.

2003-01-01

We studied oceanography (including primary production), secondary production, small schooling fish (SSF), and marine bird and mammal predators in Glacier Bay during 1999 and 2000. Results from these field efforts were combined with a review of current literature relating to the Glacier Bay environment. Since the conceptual model developed by Hale and Wright (1979) ‘changes and cycles’ continue to be the underlying theme of the Glacier Bay ecosystem. We found marked seasonality in many of the parameters that we investigated over the two years of research, and here we provide a comprehensive description of the distribution and relative abundance of a wide array of marine biota. Glacier Bay is a tidally mixed estuary that leads into basins, which stratify in summer, with the upper arms behaving as traditional estuaries. The Bay is characterized by renewal and mixing events throughout the year, and markedly higher primary production than in many neighboring southeast Alaska fjords (Hooge and Hooge, 2002). Zooplankton diversity and abundance within the upper 50 meters of the water column in Glacier Bay is similar to communities seen throughout the Gulf of Alaska. Zooplankton in the lower regions of Glacier Bay peak in abundance in late May or early June, as observed at Auke Bay and in the Gulf of Alaska. The key distinction between the lower Bay and other estuaries in the Gulf of Alaska is that a second smaller peak in densities occurs in August. The upper Bay behaved uniformly in temporal trends, peaking in July. Densities had begun to decline in August, but were still more than twice those observed in that region in May. The highest density of zooplankton observed was 17,870 organisms/m3 in Tarr Inlet during July. Trends in zooplankton community abundance and diversity within the lower Bay were distinct from upper-Glacier Bay trends. Whereas the lower Bay is strongly influenced by Gulf of Alaska processes, local processes are the strongest influence in the upper-Bay

Unexpected spatial impact of treatment plant discharges induced by episodic hydrodynamic events: Modelling Lagrangian transport of fine particles by Northern Current intrusions in the bays of Marseille (France).

Science.gov (United States)

Millet, Bertrand; Pinazo, Christel; Banaru, Daniela; Pagès, Rémi; Guiart, Pierre; Pairaud, Ivane

2018-01-01

Our study highlights the Lagrangian transport of solid particles discharged at the Marseille Wastewater Treatment Plant (WWTP), located at Cortiou on the southern coastline. We focused on episodic situations characterized by a coastal circulation pattern induced by intrusion events of the Northern Current (NC) on the continental shelf, associated with SE wind regimes. We computed, using MARS3D-RHOMA and ICHTHYOP models, the particle trajectories from a patch of 5.104 passive and conservative fine particles released at the WWTP outlet, during 2 chosen representative periods of intrusion of the NC in June 2008 and in October 2011, associated with S-SE and E-SE winds, respectively. Unexpected results highlighted that the amount of particles reaching the vulnerable shorelines of both northern and southern bays accounted for 21.2% and 46.3% of the WWTP initial patch, in June 2008 and October 2011, respectively. Finally, a conceptual diagram is proposed to highlight the mechanisms of dispersion within the bays of Marseille of the fine particles released at the WWTP outlet that have long been underestimated.

Permafrost and peatland evolution in the northern Hudson Bay lowland, Manitoba

Energy Technology Data Exchange (ETDEWEB)

Dyke, L.D.; Sladen, W.E. [Natural Resources Canada, Ottawa, ON (Canada). Geological Survey of Canada

2010-12-15

This article reported on a study that investigated the sensitivity of peat plateau terrain to continued climate warming in the area of the northern Hudson Bay lowland. Snow and shallow standing water were assessed as the environmental factors most likely to create above-freezing ground temperatures in peat plateau terrain that is otherwise frozen. The relationships between air and ground temperatures in creating these surface environmental conditions were determined and used with air temperature records to predict whether peat plateaus will thaw as a result of foreseeable climate warming. Lake erosion was also assessed as a mechanism for the degradation of frozen peat plateau terrain. Environmental conditions that result in elevated ground temperatures at the margin of peat plateaus either eliminate permafrost or promote permafrost temperatures that are warmer than those beneath unforested peat plateaus. Under present climatic conditions, the process in which a frozen peat plateau degrades and transitions to fen is slow, but with continued warming the subsidence at plateau edges will become more pronounced, accelerating the subsidence process. The consequences of continued warming will be the expansion of thawed zones, subsidence at plateau margins, and potentially the collapse of plateau surfaces and conversion into fen. Peat plateau bog is also being lost to wave erosion of subsiding plateau borders at lake shorelines. 30 refs., 14 figs.

Model outputs - Developing end-to-end models of the Gulf of California

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The purpose of this project is to develop spatially discrete end-to-end models of the northern Gulf of California, linking oceanography, biogeochemistry, food web...

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

Directory of Open Access Journals (Sweden)

Xinrong Ren

2014-04-01

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

Environmental and ammonoid faunal changes related to Albian Bay of Biscay opening: Insights from the northern margin of the Basque-Cantabrian Basin

Science.gov (United States)

Agirrezabala, Luis M.; López-Horgue, Mikel A.

2017-12-01

The opening and ocean floor spreading of the Bay of Biscay began in the earliest Albian. The integrative study of the Albian sedimentary record and its ammonoid fauna (around 250 specimens) from the northern margin of the Basque-Cantabrian Basin indicates that environmental changes, occurred as a consequence of the Bay of Biscay opening, triggered significant ammonoid bioevents. Main bioevents are diversity changes in the ammonoid associations, occurrence of large forms (diameter up to 0.45 m) and the incursion of elements from other basins. Time-correlation of faulting pulses with ammonoid bioevents indicates that transtensive tectonics was ultimately the major control on the marine environmental conditions such as depth, sea bottom physiography, seaways, sedimentary systems and sea-water chemistry. The pulsating faulting during the Albian led to the increment of the subsidence rate, the deepening and widening of the margin and the progressive increase in the oceanic circulation between the margin and the nascent Bay of Biscay and North Atlantic. In addition, Albian synsedimentary faults constituted conduits for ascending magmas and hydrocarbon-rich hydrothermal fluids, which expelled to the seafloor, causing changes in the sediments, the sea-water chemistry (fertilization) and biota. The integration of sedimentological and palaeontological data has given the basis for a conceptual model of the ammonoid habitats.

USGS Tampa Bay Pilot Study

Science.gov (United States)

Yates, K.K.; Cronin, T. M.; Crane, M.; Hansen, M.; Nayeghandi, A.; Swarzenski, P.; Edgar, T.; Brooks, G.R.; Suthard, B.; Hine, A.; Locker, S.; Willard, D.A.; Hastings, D.; Flower, B.; Hollander, D.; Larson, R.A.; Smith, K.

2007-01-01

Many of the nation's estuaries have been environmentally stressed since the turn of the 20th century and will continue to be impacted in the future. Tampa Bay, one the Gulf of Mexico's largest estuaries, exemplifies the threats that our estuaries face (EPA Report 2001, Tampa Bay Estuary Program-Comprehensive Conservation and Management Plan (TBEP-CCMP)). More than 2 million people live in the Tampa Bay watershed, and the population constitutes to grow. Demand for freshwater resources, conversion of undeveloped areas to resident and industrial uses, increases in storm-water runoff, and increased air pollution from urban and industrial sources are some of the known human activities that impact Tampa Bay. Beginning on 2001, additional anthropogenic modifications began in Tampa Bat including construction of an underwater gas pipeline and a desalinization plant, expansion of existing ports, and increased freshwater withdrawal from three major tributaries to the bay. In January of 2001, the Tampa Bay Estuary Program (TBEP) and its partners identifies a critical need for participation from the U.S. Geological Survey (USGS) in providing multidisciplinary expertise and a regional-scale, integrated science approach to address complex scientific research issue and critical scientific information gaps that are necessary for continued restoration and preservation of Tampa Bay. Tampa Bay stakeholders identified several critical science gaps for which USGS expertise was needed (Yates et al. 2001). These critical science gaps fall under four topical categories (or system components): 1) water and sediment quality, 2) hydrodynamics, 3) geology and geomorphology, and 4) ecosystem structure and function. Scientists and resource managers participating in Tampa Bay studies recognize that it is no longer sufficient to simply examine each of these estuarine system components individually, Rather, the interrelation among system components must be understood to develop conceptual and

Subsurface gas hydrates in the northern Gulf of Mexico

Science.gov (United States)

Boswell, Ray; Collett, Timothy S.; Frye, Matthew; Shedd, William; McConnell, Daniel R.; Shelander, Dianna

2012-01-01

The northernGulf of Mexico (GoM) has long been a focus area for the study of gashydrates. Throughout the 1980s and 1990s, work focused on massive gashydrates deposits that were found to form at and near the seafloor in association with hydrocarbon seeps. However, as global scientific and industrial interest in assessment of the drilling hazards and resource implications of gashydrate accelerated, focus shifted to understanding the nature and abundance of "buried" gashydrates. Through 2005, despite the drilling of more than 1200 oil and gas industry wells through the gashydrate stability zone, published evidence of significant sub-seafloor gashydrate in the GoM was lacking. A 2005 drilling program by the GoM GasHydrate Joint Industry Project (the JIP) provided an initial confirmation of the occurrence of gashydrates below the GoM seafloor. In 2006, release of data from a 2003 industry well in Alaminos Canyon 818 provided initial documentation of gashydrate occurrence at high concentrations in sand reservoirs in the GoM. From 2006 to 2008, the JIP facilitated the integration of geophysical and geological data to identify sites prospective for gashydrate-bearing sands, culminating in the recommendation of numerous drilling targets within four sites spanning a range of typical deepwater settings. Concurrent with, but independent of, the JIP prospecting effort, the Bureau of Ocean Energy Management (BOEM) conducted a preliminary assessment of the GoM gashydratepetroleum system, resulting in an estimate of 607 trillion cubic meters (21,444 trillion cubic feet) gas-in-place of which roughly one-third occurs at expected high concentrations in sand reservoirs. In 2009, the JIP drilled seven wells at three sites, discovering gashydrate at high saturation in sand reservoirs in four wells and suspected gashydrate at low to moderate saturations in two other wells. These results provide an initial confirmation of the complex nature and occurrence of gashydrate-bearing sands in

Random Forest population modelling of striped and common-bottlenose dolphins in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea)

Science.gov (United States)

Carlucci, Roberto; Cipriano, Giulia; Paoli, Chiara; Ricci, Pasquale; Fanizza, Carmelo; Capezzuto, Francesca; Vassallo, Paolo

2018-05-01

This study provides the first estimates of density and abundance of the striped dolphin Stenella coeruleoalba and common bottlenose dolphin Tursiops truncatus in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) and identifies the predictive variables mainly influencing their occurrence and concentration in the study area. Conventional Distance Sampling (CDS) and the Delta approach on Random Forest (DaRF) methods have been applied to sightings data collected between 2009 and 2016 during standardized vessel-based surveys, providing similar outcomes. The mean value of density over the entire study area was 0.72 ± 0.26 specimens/km2 for the striped dolphin and 0.47 ± 0.09 specimens/km2 for the common bottlenose dolphin. The abundance estimated by DaRF in the Gulf of Taranto was 10080 ± 3584 specimens of S. coeruleoalba and 6580 ± 1270 specimens of T. truncatus, respectively. Eight predictive variables were selected, considering both the local physiographic features and human activities existing in the investigated area. The explanatory variables depth, distance from the coast, distance from industrial areas and distance from areas exploited by fishery seem to play a key role in influencing the spatial distribution of both species, whereas the geomorphological variables proved to be the most significant factors shaping the concentration of both dolphins. The establishment of a Specially Protected Area of Mediterranean Importance (SPAMI) according the SPA/BD Protocol in the Gulf of Taranto is indicated as an effective management tool for the conservation of both dolphin populations in the Central-eastern Mediterranean Sea.

A retrospective view of the development of the Gulf of Bothnia ecosystem

Science.gov (United States)

Kuosa, Harri; Fleming-Lehtinen, Vivi; Lehtinen, Sirpa; Lehtiniemi, Maiju; Nygård, Henrik; Raateoja, Mika; Raitaniemi, Jari; Tuimala, Jarno; Uusitalo, Laura; Suikkanen, Sanna

2017-03-01

We analysed long-term monitoring data from 1979 to 2012 in the Gulf of Bothnia, the northernmost extension of the Baltic Sea, to examine changes in the summer food web structure, and to reveal the factors causing the observed changes. Of the two sub-basins in the Gulf of Bothnia, the Bothnian Sea is more dynamic in its hydrography and food web structure than the Bothnian Bay, due to the variable influence of the more eutrophic and more saline Baltic Proper. Variation in deep-water intrusion from the main Baltic Proper, and its effect on salinity and stratification, had a clear effect on the phyto- and zooplankton communities in the Bothnian Sea. Probably due to this intrusion, the nutrient status in this basin has also changed in terms of nitrogen limitation, with subsequent class- and genus-level changes in phytoplankton community composition. The migration of cod to the Bothnian Sea during the 1980s had profound effects on the herring population, but cascading effects affecting the basis of the food web were not obvious. In contrast to a more pronounced interplay of both top-down control and bottom-up nutrient limitation of the Bothnian Sea, the Bothnian Bay food web was mostly driven by hydrography and climate, and major changes were observed in the basis of the food web. Community changes were observed in both basins in the Gulf of Bothnia throughout the entire time period. Human influence considerably affects both the basis of the food web and its very top, where man has replaced the natural top predators. Though the eutrophication status of the Gulf has been rather stable, the results indicate that the potential symptoms should be surveyed specifically in the Bothnian Sea, and that management of Baltic herring stocks requires an understanding, and thus monitoring, of the entire food web.

Macrobenthic Community Structure in the Northwestern Arabian Gulf, Twelve Years after the 1991 Oil Spill

KAUST Repository

Joydas, Thadickal V.

2017-08-03

The biota in the Arabian Gulf faces stress both from natural (i.e., hyper salinity and high sea surface temperature), and human (i.e., from oil-related activities) sources. The western Arabian Gulf was also impacted by world\\'s largest oil spill (1991 Oil Spill). However, benthic research in this region is scarce and most of the studies have been conducted only in small areas. Here, we present data on macrobenthos collected during 2002–2003 from the open waters and inner bays in the northwestern Arabian Gulf aimed to assess the ecological status and also to evaluate the long-term impact, if any, of the 1991 Oil Spill. A total of 392 macrobenthic taxa with an average (±SE) species richness (S) of 71 ± 2, Shannon-Wiener species diversity (H′) of 4.9 ± 0.1, and density of 3,181 ± 359 ind. m−2 was recorded from the open water stations. The open waters have “slightly disturbed” (according to AZTI\\'s Marine Biotic Index, AMBI) conditions, with “good-high” (according to multivariate-AMBI, M-AMBI) ecological status indicating the absence of long-term impacts of the oil spill. Overall, 162 taxa were recorded from inner bays with average (±SE) values of S 41 ± 9, H′ 3.48 ± 0.39, and density 4,203 ± 1,042 ind. m−2. The lower TPH (Total Petroleum Hydrocarbons) stations (LTS, TPH concentrations <70 mg kg−2) show relatively higher S, H\\' and density compared to the higher TPH stations (HTS, TPH concentrations ≥100 mg kg−2). In the inner bays, AMBI values indicate slightly disturbed conditions at all stations except one, which is moderately disturbed. M-AMBI values indicate good status at LTS, while, high, good, moderate, and poor status at HTS. The “moderately disturbed” conditions with “moderate-poor” ecological status in some locations of the inner bays specify a severe long-term impact of the oil spill.

Macrobenthic Community Structure in the Northwestern Arabian Gulf, Twelve Years after the 1991 Oil Spill

Directory of Open Access Journals (Sweden)

Thadickal V. Joydas

2017-08-01

Full Text Available The biota in the Arabian Gulf faces stress both from natural (i.e., hyper salinity and high sea surface temperature, and human (i.e., from oil-related activities sources. The western Arabian Gulf was also impacted by world's largest oil spill (1991 Oil Spill. However, benthic research in this region is scarce and most of the studies have been conducted only in small areas. Here, we present data on macrobenthos collected during 2002–2003 from the open waters and inner bays in the northwestern Arabian Gulf aimed to assess the ecological status and also to evaluate the long-term impact, if any, of the 1991 Oil Spill. A total of 392 macrobenthic taxa with an average (±SE species richness (S of 71 ± 2, Shannon-Wiener species diversity (H′ of 4.9 ± 0.1, and density of 3,181 ± 359 ind. m−2 was recorded from the open water stations. The open waters have “slightly disturbed” (according to AZTI's Marine Biotic Index, AMBI conditions, with “good-high” (according to multivariate-AMBI, M-AMBI ecological status indicating the absence of long-term impacts of the oil spill. Overall, 162 taxa were recorded from inner bays with average (±SE values of S 41 ± 9, H′ 3.48 ± 0.39, and density 4,203 ± 1,042 ind. m−2. The lower TPH (Total Petroleum Hydrocarbons stations (LTS, TPH concentrations <70 mg kg−2 show relatively higher S, H' and density compared to the higher TPH stations (HTS, TPH concentrations ≥100 mg kg−2. In the inner bays, AMBI values indicate slightly disturbed conditions at all stations except one, which is moderately disturbed. M-AMBI values indicate good status at LTS, while, high, good, moderate, and poor status at HTS. The “moderately disturbed” conditions with “moderate-poor” ecological status in some locations of the inner bays specify a severe long-term impact of the oil spill.

Macrobenthic Community Structure in the Northwestern Arabian Gulf, Twelve Years after the 1991 Oil Spill

KAUST Repository

Joydas, Thadickal V.; Qurban, Mohammad A.; Borja, Angel; Krishnakumar, Periyadan K.; Al-Suwailem, Abdulaziz M.

2017-01-01

The biota in the Arabian Gulf faces stress both from natural (i.e., hyper salinity and high sea surface temperature), and human (i.e., from oil-related activities) sources. The western Arabian Gulf was also impacted by world's largest oil spill (1991 Oil Spill). However, benthic research in this region is scarce and most of the studies have been conducted only in small areas. Here, we present data on macrobenthos collected during 2002–2003 from the open waters and inner bays in the northwestern Arabian Gulf aimed to assess the ecological status and also to evaluate the long-term impact, if any, of the 1991 Oil Spill. A total of 392 macrobenthic taxa with an average (±SE) species richness (S) of 71 ± 2, Shannon-Wiener species diversity (H′) of 4.9 ± 0.1, and density of 3,181 ± 359 ind. m−2 was recorded from the open water stations. The open waters have “slightly disturbed” (according to AZTI's Marine Biotic Index, AMBI) conditions, with “good-high” (according to multivariate-AMBI, M-AMBI) ecological status indicating the absence of long-term impacts of the oil spill. Overall, 162 taxa were recorded from inner bays with average (±SE) values of S 41 ± 9, H′ 3.48 ± 0.39, and density 4,203 ± 1,042 ind. m−2. The lower TPH (Total Petroleum Hydrocarbons) stations (LTS, TPH concentrations <70 mg kg−2) show relatively higher S, H' and density compared to the higher TPH stations (HTS, TPH concentrations ≥100 mg kg−2). In the inner bays, AMBI values indicate slightly disturbed conditions at all stations except one, which is moderately disturbed. M-AMBI values indicate good status at LTS, while, high, good, moderate, and poor status at HTS. The “moderately disturbed” conditions with “moderate-poor” ecological status in some locations of the inner bays specify a severe long-term impact of the oil spill.

Phytoplankton growth, dissipation, and succession in estuarine environments. [Chesapeake Bay

Energy Technology Data Exchange (ETDEWEB)

Seliger, H H

1976-01-01

Two major advances in a study of phytoplankton ecology in the Chesapeake Bay are reported. The annual subsurface transport of a dinoflagellate species (Prorocentrum mariae labouriae) from the mouth of the bay a distance northward of 120 nautical miles to the region of the Bay Bridge was followed. Prorocentrum is a major seasonal dinoflagellate in the Chespeake Bay and annually has been reported to form mahogany tides, dense reddish-brown patches, in the northern bay beginning in late spring and continuing through the summer. Subsequent to this annual appearance the Prorocentrum spread southward and into the western tributary estuaries. The physiological behavioral characteristics of the Prorocentrum were correlated with the physical water movements in the bay. A phytoplankton cage technique for the measurement in situ of the growth rates of natural mixed populations is described. (CH)

Harmful Algal Blooms in the Mississippi Sound and Mobile Bay: Using MODIS Aqua and In Situ Data for HABs in the Northern Gulf of Mexico

National Research Council Canada - National Science Library

Holiday, Dan; Carter, Gregory; Gould, Richard W; MacIntyre, Hugh

2007-01-01

.... Phytoplankton populations and in situ water quality were monitored at 3 to 6 week intervals at 17 locations in Mobile Bay and the Mississippi Sound beginning in July 2005 and continuing thru June...

Long-term morphologic evolution of the Hangzhou Bay, China

Science.gov (United States)

Wen, W.; Zhijun, D.; Hualiang, X.

2013-12-01

Estuaries are the most productive ecosystems of coastal zones in the world, which are significant to mankind as places of navigation, recreation and commerce as well as extensive and diverse habitats for wildlife. However, most estuary environments in the world had occurred greatly changes in recent decades. These estuaries have suffered from impacts of forcing factors including wave climate, mean sea level change and storm surge, especial to the intensive human activities such as training wall construction, channel dredging, sand mining and dam constructions. Thus, there have been increasing concerns about estuary environment changes under effects of different factors. Riverine loads into the Changjiang Estuary have declined dramatically with the construction of Three Gorges Dam (TGD) in 2003. The morphological evolution of the Hangzhou bay that located the southern proximity of the Yangtze estuary starts to attract increasing attentions due to most material of the Hangzhou bay received from Yangtze estuary. In this paper, historical bathymetric charts were digitized and analyzed within a GIS to provide quantitative estimate of changes in volumes in different regions below 0 m elevation. The results show that Hangzhou bay has experienced a major loss in estuarine volume of about 15% with annual mean sediment deposition rate of 80 million m3/a during the last 75 years. However, there is a large-scale spatial adjustment in Hangzhou bay: Bathymetric changes of the Hangzhou bay can be rapidly shifted within the range of 8-10 classes. Volume of the Jinshanzui upstream of the Hangzhou bay has obviously decreased in the last 75 years, especially during 2003-2008. However, Volume of the southern Hangzhou bay has experienced slowly decrease with minor deposition. The northern Hangzhou bay had largely volume changes with rapidly decrease during 1931-1981, and drastically increase since 2003. Further analysis of the bathymetric data relating to possible factors indicates

Prey and plastic ingestion of Pacific Northern Fulmars (Fulmarus glacialis rogersii) from Monterey Bay, California.

Science.gov (United States)

Donnelly-Greenan, Erica L; Harvey, James T; Nevins, Hannahrose M; Hester, Michelle M; Walker, William A

2014-08-15

Marine plastic pollution affects seabirds, including Pacific Northern Fulmars (Fulmarus glacialis rodgersii), that feed at the surface and mistake plastic for prey or incidentally ingest it. Direct and indirect health issues can result, including satiety and possibly leading to inefficient foraging. Our objective was to examine fulmar body condition, identify cephalopod diet to species, enumerate and weigh ingested plastic, and determine if prey number and size were correlated with ingested plastics in beach-cast fulmars wintering in Monterey Bay California (2003, n=178: 2007, n=185). Fulmars consumed mostly Gonatus pyros, G. onyx, and G. californiensis of similar size for both years. We found a significant negative correlation between pectoral muscle index and average size of cephalopod beaks per stomach; a significant increase in plastic categories between 2003 and 2007; and no significant correlation between number and mass of plastic compared with number and size of prey for either year. Copyright © 2014 Elsevier Ltd. All rights reserved.

Predominant Nearshore Sediment Dispersal Patterns in Manila Bay

Directory of Open Access Journals (Sweden)

Fernando Siringan

1997-12-01

Full Text Available Net nearshore sediment drift patterns in Manila Bay were determined by combining the coastal geomorphology depicted in 1 : 50,000scale topographic maps and Synthetic Aperture Radar (SAR images, with changes in shoreline position and predominant longshore current directions derived from the interaction of locally generated waves and bay morphology.Manila Bay is fringed by a variety of coastal subenvironments that reflect changing balances of fluvial, wave, and tidal processes. Along the northern coast, a broad tidal-river delta plain stretching from Bataan to Bulacan indicates the importance of tides, where the lateral extent of tidal influences is amplified by the very gentle coastal gradients. In contrast, along the Cavite coast sandy strandplains, spits, and wave-dominated deltas attest to the geomorphic importance of waves that enter the bay from the South China Sea.The estimates of net sediment drift derived from geomorphological, shoreline-change, and meteorological information are generally in good agreement. Sediment drift directions are predominantly to the northeast along Cavite, to the northwest along Manila and Bulacan, and to the north along Bataan. Wave refraction and eddy formation at the tip of the Cavite Spit cause southwestward sediment drift along the coast from Zapote to Kawit. Geomorphology indicates that onshore-offshore sediment transport is probably more important than alongshore transport along the coast fronting the tidal delta plain of northern Manila Bay. Disagreements between the geomorphic-derived and predicted net sediment drift directions may be due to interactions of wave-generated longshore currents with wind- and tide-generated currents.

Northern Gulf 1 Arc-second NAVD 88 Coast Digital Elevation Model

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NOAA's National Geophysical Data Center (NGDC) is building high-resolution digital elevation models (DEMs) for select U.S. coastal regions in the Gulf of Mexico....

Assessment of Tsunami-related Geohazard Assessment for Coasts of Hersek Peninsula and Gulf of İzmit

Directory of Open Access Journals (Sweden)

Cem Gazioğlu

2017-05-01

Full Text Available Tsunamis are one of the most dreadful natural disasters; they could cause abysmal damage to all kind of lives in the hinterland within instantly. It is a major right-lateral moving fault that runs along the tectonic boundary between the Eurasian Plate to the north and the Anatolian Plate to the south. The western segment of the North Anatolian Fault splits into three main branches. The northern one of NAF is generally subdivided in several subsegments that have been the source of frequent large historical earthquakes. The Sea of Marmara coasts is located on the western extension of the NAFZ which is one of the most important active faults with strike-slip characteristics, which are not likely to generate tsunami. However, in the light of tsunami catalogs based on historical documents, it is possible to say that Sea of Marmara has tsunamigenic potential. The İstanbul shorelines, Gemlik Bay, Kapıdağ N-NE shores, Gelibolu, Hersek Peinsula and Gulf of İzmit are one of the most significant geohazards in Sea of Marmara due to the tsunami effect.

Transport and potential vorticity in the Bay of Bengal during the southwest monsoon

Digital Repository Service at National Institute of Oceanography (India)

Murty, V.S.N.; Murty, C.S.; Sarma, Y.V.B.; Rao, D.P.; Sastry, J.S.; Rao, G.R.L.

Current (EBC) contributed to an influx of 3.5 x 10 sup(6 m sup(3/s water respectively. The influence of overlying less saline, fresher water at the northern Bay: Ekman suction due to the wind stress curl in the central Bay; and the east-flowing IMC...

Sedimentological Characterization of a Deepwater Methane Hydrate Reservoir in Green Canyon 955, Northern Gulf of Mexico

Science.gov (United States)

Meazell, K.; Flemings, P. B.

2017-12-01

Grain size is a controlling factor of hydrate saturation within a Pleistocene channel-levee system investigated by the UT-GOM2-1 expedition within the deepwater northern Gulf of Mexico. Laser diffraction and settling experiments conducted on sediments from 413-440 meters below the seafloor reveal the presence of two interbedded lithologic units, identified as a silty sand and a clayey silt, according Shepard's classification system. The sand-rich lithofacies has low density and high p-wave velocity, suggesting a high degree of hydrate saturation. Conversely, the clay and silt dominated lithofacies is characterized by a higher density and low p-wave velocity, suggesting low hydrate saturation. The sand-rich lithofacies is well-sorted and displays abundant ripple lamination, indicative of deposition within a high-energy environment. The clayey-silt is poorly-sorted and lacks sedimentary structures. The two lithofacies are interbedded throughout the reservoir unit; however, the relative abundance of the sand-rich lithofacies increases with depth, suggesting a potential decrease in flow energy or sediment flux over time, resulting in the most favorable reservoir properties near the base of the unit.

Coccolithophore diversity and dynamics at a coastal site in the Gulf of Trieste (northern Adriatic Sea)

Science.gov (United States)

Cerino, Federica; Malinverno, Elisa; Fornasaro, Daniela; Kralj, Martina; Cabrini, Marina

2017-09-01

Two years-data (May 2011-February 2013) obtained from a monthly sampling carried out at the coastal long term Ecological Research station C1-LTER in the Gulf of Trieste (northern Adriatic Sea) were analysed to describe the seasonal dynamics and diversity of coccolithophore assemblages and to assess their relationship with environmental forcing. Coccolithophores represented 10.7% of the total Utermöhl phytoplankton that were mainly dominated by small (Emiliania huxleyi, and a secondary peak in May-June (0.7-15.0 · 104 coccospheres L-1), coinciding with the increase of the light intensity and the beginning of the seasonal stratification, dominated by holococcolithophores and small Syracosphaera species. The most abundant taxa were E. huxleyi and holococcolithophores, followed by Acanthoica quattrospina, Syracosphaera species and other minor species. Statistical analyses recognized four distinct groups, corresponding to seasonal variations of environmental conditions. Considering the two years, some species displayed a recurrent seasonal pattern highlighting possible species-specific ecological requirements, while others showed an interannual variability probably due to local factors.

Impacts of springtime biomass burning in the northern Southeast Asia on marine organic aerosols over the Gulf of Tonkin, China.

Science.gov (United States)

Zheng, Lishan; Yang, Xiaoyang; Lai, Senchao; Ren, Hong; Yue, Siyao; Zhang, Yingyi; Huang, Xin; Gao, Yuanguan; Sun, Yele; Wang, Zifa; Fu, Pingqing

2018-06-01

Fine particles (PM 2.5 ) samples, collected at Weizhou Island over the Gulf of Tonkin on a daytime and nighttime basis in the spring of 2015, were analyzed for primary and secondary organic tracers, together with organic carbon (OC), elemental carbon (EC), and stable carbon isotopic composition (δ 13 C) of total carbon (TC). Five organic compound classes, including saccharides, lignin/resin products, fatty acids, biogenic SOA tracers and phthalic acids, were quantified by gas chromatography/mass spectrometry (GC/MS). Levoglucosan was the most abundant organic species, indicating that the sampling site was under strong influence of biomass burning. Based on the tracer-based methods, the biomass-burning-derived fraction was estimated to be the dominant contributor to aerosol OC, accounting for 15.7% ± 11.1% and 22.2% ± 17.4% of OC in daytime and nighttime samples, respectively. In two episodes E1 and E2, organic aerosols characterized by elevated concentrations of levoglucosan as well as its isomers, sugar compounds, lignin products, high molecular weight (HMW) fatty acids and β-caryophyllinic acid, were attributed to the influence of intensive biomass burning in the northern Southeast Asia (SEA). However, the discrepancies in the ratios of levoglucosan to mannosan (L/M) and OC (L/OC) as well as the δ 13 C values suggest the type of biomass burning and the sources of organic aerosols in E1 and E2 were different. Hardwood and/or C 4 plants were the major burning materials in E1, while burning of softwood and/or C 3 plants played important role in E2. Furthermore, more complex sources and enhanced secondary contribution were found to play a part in organic aerosols in E2. This study highlights the significant influence of springtime biomass burning in the northern SEA to the organic molecular compositions of marine aerosols over the Gulf of Tonkin. Copyright © 2018 Elsevier Ltd. All rights reserved.

Temporal variability in sediment PAHs accumulation in the northern Gulf of Mexico Shelf

Science.gov (United States)

Bam, W.; Maiti, K.; Adhikari, P. L.

2017-12-01

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous group of organic pollutants, some of which are known to be toxic, and/or carcinogenic to humans. The major source of these PAHs into the northern Gulf of Mexico (NGOM) are Mississippi River discharge, coastal erosion, atmospheric deposition, and numerous natural oil seeps and spills. In addition to these background source of PAHs, the Deepwater Horizon (DWH) oil spill in 2010 added 21,000 tons of PAHs into the NGOM water. In this study, we measured PAHs distribution and accumulation rates in coastal sediments near the Mississippi River mouth in 2011 and 2015 to understand the effect of DWH oil spill in PAHs accumulation in coastal sediments. Sediment cores were collected and sliced at 1 cm interval to measure PAHs concentration, and to estimate 210Pb-based sedimentation and the PAHs' accumulation rates. The results showed that the sediment deposition rates in this region varied between 0.5 to 0.9 cm/yr. The results also showed that the concentration of total PAHs (ΣPAH43) and their accumulation rates vary between 68 - 100 ng g-1 and 7 - 160 ng cm-2 yr-1, respectively. While the PAHs accumulation rate in coastal sediment varied over the years, there is no significant variation in PAHs accumulation rate before and after the DWH oil spill.

Status of macrobenthic community of Manifa-Tanajib Bay System of Saudi Arabia based on a once-off sampling event

KAUST Repository

Joydas, Thadickal Viswanathan

2011-06-01

Shallow water bays located in the western Arabian Gulf experience harsh environmental conditions. Some of these bays, including Manifa-Tanajib Bay System (MTBS), were also exposed to the 1991 oil pollution event. This study investigates the status of the macrobenthos in MTBS during 2006. This bay system is characterized by very shallow inner bays with elevated salinity and temperature compared to the rest of the bay area. As a result mainly of the hyper salinity, the inner bay communities are distinct from the outer bay communities. Overall, fairly high species richness with several rare species was observed. High Shannon-Wiener diversity values and ABC plots indicated the healthy status of the polychaete communities, while BOPA index indicated slightly polluted status in 20% of the stations. The oil sensitive amphipods were not completely re-colonized in 20% of the stations, even after 15. years of recovery from the 1991 oil spill. © 2011 Elsevier Ltd.

Gulf of Mexico Integrated Science - Tampa Bay Study - Characterization of Tidal Wetlands

Science.gov (United States)

McIvor, Carole

2005-01-01

Tidal wetlands in Tampa Bay, Florida, consist of mangrove forests and salt marshes. Wetlands buffer storm surges, provide fish and wildlife habitat, and enhance water quality through the removal of water-borne nutrients and contaminants. Substantial areas of both mangroves and salt marshes have been lost to agricultural, residential, and industrial development in this urban estuary. Wetlands researchers are characterizing the biological components of tidal wetlands and examining the physical factors such as salinity, tidal flushing, and sediment deposition that control the composition of tidal wetland habitats. Wetlands restoration is a priority of resource managers in Tampa Bay. Baseline studies such as these are needed for successful restoration planning and evaluation.

Benthic community structure and composition in sediment from the northern Gulf of Mexico shoreline, Texas to Florida

Science.gov (United States)

Demopoulos, Amanda W.J.; Strom, Douglas G.

2012-01-01

From April 20 through July 15, 2010, approximately 4.93 million barrels of crude oil spilled into the Gulf of Mexico from the British Petroleum Macondo-1 well, representing the largest spill in U.S. waters. Baseline benthic community conditions were assessed from shoreline sediment samples collected from 56 stations within the swash zone (for example, sample depth ranged from 0 to 1.5 feet) along the northern Gulf of Mexico coastline. These sites were selected because they had a high probability of being impacted by the oil. Cores collected at 24 stations contained no sediment infauna. Benthic community metrics varied greatly among the remaining stations. Mississippi stations had the highest mean abundances (38.9 ± 23.9 individuals per 32 square centimeters (cm2); range: 0 to 186), while Texas had the lowest abundances, 4.9 ± 3 individuals per 32 cm2 (range: 0 to 25). Dominant phyla included Annelida, Arthropoda, and Mollusca, but proportional contributions of each group varied by State. Diversity indices Margalef's richness (d) and Shannon-Wiener diversity (H') were highest at Louisiana and Mississippi stations (0.4 and 0.4, for both, respectively) and lowest at Texas (values for both indices were 0.1 ± 0.1). Evenness (J') was low for all the States, ranging from 0.2 to 0.3, indicating a high degree of patchiness at these sites. Across stations within a State, average similarity ranged from 11.1 percent (Mississippi) to 41.1 percent (Louisiana). Low within-state similarity may be a consequence of differing habitat and physical environment conditions. Results provide necessary baseline information that will facilitate future comparisons with post-spill community metrics.

33 CFR 334.860 - San Diego Bay, Calif., Naval Amphibious Base; restricted area.

Science.gov (United States)

2010-07-01

... Amphibious Base; restricted area. 334.860 Section 334.860 Navigation and Navigable Waters CORPS OF ENGINEERS... Bay, Calif., Naval Amphibious Base; restricted area. (a) The Area. The water of the Pacific Ocean in Middle San Diego Bay in an area extending from the northern and eastern boundary of the Naval Amphibious...

Radionuclides in sediments from Port Phillip Bay, Australia

International Nuclear Information System (INIS)

Smith, J.D.; Tinker, R.A.; Towler, P.H.

1998-01-01

Full text: Sediment cores were collected from two sites in Port Phillip Bay, Australia, in 1994 and 1995. The concentration of 210 Pb and parameters including water content were measured. The sites chosen were near the centre of the bay where fine sediment accumulates, and towards the northern end of the bay closer to the mouth of the Yarra River. The mid-bay sediment had a high water content (about 1.8 g water per g dry sediment) and a supported 210 Pb activity of about 22 mBq per g of dry sediment. The sediments from further north in the bay were more consolidated, with a lower water content (about 0.6 g water per g dry sediment), and had a supported 210 Pb activity of about 6 mBq per g of dry sediment. Unsupported 210 Pb occurred to depths of about 10 cm in the mid-bay sediment and about 20 cm in sediment from further north in the bay. Models incorporating the water and 210 Pb contents of the sediments were used to calculate possible rates of sediment accumulation and mixing. The distribution of other radionuclides was used as an aid in understanding the sediment behaviour in Port Phillip Bay

Microplastics contamination in molluscs from the northern part of the Persian Gulf.

Science.gov (United States)

Naji, Abolfazl; Nuri, Marzieh; Vethaak, A Dick

2018-04-01

Microplastics (MPs) are well-known emerging contaminants in the marine environment. A key route by which MPs can directly affect marine life is through ingestion. The objective of the present study was to evaluate the occurrence of MPs in marine life and seafood for human consumption in the Persian Gulf. We conducted a whole body analysis of MP (between 10 and 5000 μm in diameter) abundance in five species of molluscs with different feeding strategies, including both gastropods and bivalves from the littoral zone of the Iranian coast of the Persian Gulf. The mean number of total encountered MPs in all species ranged from 0.2 to 21.0 particles per g of soft tissue (wet weight) and from 3.7 to 17.7 particles per individual. Overall, microfibres followed by fragments were the most common type of MP isolated in each species (respectively > 50% and ≈26%). Film (≈14%) and pellets (≈2%) were less commonly observed. The observed MPs were classified into three size groups (ca. 10-25 μm, 25-250 μm and 250-5000 μm), and 37-58% of MPs fell into the smallest size group. Fourier transform infrared (FT-IR) analysis confirmed the presence of polyethylene (PE), polyethylene terephthalate (PET), and nylon (PA). Our results indicated that molluscan shellfish from the Persian Gulf contain MPs, with higher concentrations in a predatory species, suggesting trophic transfer of MPs in the food web. The consumption of edible species may be a source of human microplastic intake. We compared our results with those previously reported for other regions of the world and identified the need for further studies in the Persian Gulf. Copyright © 2017 Elsevier Ltd. All rights reserved.

National Oceanic and Atmospheric Administration Publishes Misleading Information on Gulf of Mexico "Dead Zone"

OpenAIRE

Courtney, Michael W.; Courtney, Joshua M.

2013-01-01

Mississippi River nutrient loads and water stratification on the Louisiana-Texas shelf contribute to an annually recurring, short-lived hypoxic bottom layer in areas of the northern Gulf of Mexico comprising less than 2% of the total Gulf of Mexico bottom area. Many publications demonstrate increases in biomass and fisheries production attributed to nutrient loading from river plumes. Decreases in fisheries production when nutrient loads are decreased are also well documented. However, the Na...

Hydrate research activities that both support and derive from the monitoring station/sea-floor Observatory, Mississippi Canyon 118, northern Gulf of Mexico

Energy Technology Data Exchange (ETDEWEB)

Lutken, Carol [Univ. of Mississippi, Oxford, MS (United States). Center for Marine Resources and Environmental Technology (CMRET)

2013-07-31

A permanent observatory has been installed on the seafloor at Federal Lease Block, Mississippi Canyon 118 (MC118), northern Gulf of Mexico. Researched and designed by the Gulf of Mexico Hydrates Research Consortium (GOM-HRC) with the geological, geophysical, geochemical and biological characterization of in situ gas hydrates systems as the research goal, the site has been designated by the Bureau of Ocean Energy Management as a permanent Research Reserve where studies of hydrates and related ocean systems may take place continuously and cooperatively into the foreseeable future. The predominant seafloor feature at MC118 is a carbonate-hydrate complex, officially named Woolsey Mound for the founder of both the GOM-HRC and the concept of the permanent seafloor hydrates research facility, the late James Robert “Bob” Woolsey. As primary investigator of the overall project until his death in mid-2008, Woolsey provided key scientific input and served as chief administrator for the Monitoring Station/ Seafloor Observatory (MS-SFO). This final technical report presents highlights of research and accomplishments to date. Although not all projects reached the status originally envisioned, they are all either complete or positioned for completion at the earliest opportunity. All Department of Energy funds have been exhausted in this effort but, in addition, leveraged to great advantage with additional federal input to the project and matched efforts and resources. This report contains final reports on all subcontracts issued by the University of Mississippi, Administrators of the project, Hydrate research activities that both support and derive from the monitoring station/sea-floor Observatory, Mississippi Canyon 118, northern Gulf of Mexico, as well as status reports on the major components of the project. All subcontractors have fulfilled their primary obligations. Without continued funds designated for further project development, the Monitoring Station

Smoke in the Gulf of Mexico

Science.gov (United States)

2002-01-01

This Sea-viewing Wide Field-of-view Sensor (SeaWiFS) image of the Bay of Campeche, acquired January 17, 2001, shows a 300-kilometer long smoke plume streaming towards the northwest from around 19.4o North and 92o West, the location of the Akal oil field. In the lower right (southeast) corner of the image is the country of El Salvador, site of a magnitude 7.6 earthquake on January 13, 2001. On the Pacific side of Southern Mexico, the productive waters of the Gulf of Tehuantepec are visible. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

Vertical and horizontal resolution dependency in the model representation of tracer dispersion along the continental slope in the northern Gulf of Mexico

Science.gov (United States)

Bracco, Annalisa; Choi, Jun; Kurian, Jaison; Chang, Ping

2018-02-01

A set of nine regional ocean model simulations at various horizontal (from 1 to 9 km) and vertical (from 25 to 150 layers) resolutions with different vertical mixing parameterizations is carried out to examine the transport and mixing of a passive tracer released near the ocean bottom over the continental slope in the northern Gulf of Mexico. The release location is in proximity to the Deepwater Horizon oil well that ruptured in April 2010. Horizontal and diapycnal diffusivities are calculated and their dependence on the model set-up and on the representation of mesoscale and submesoscale circulations is discussed. Horizontal and vertical resolutions play a comparable role in determining the modeled horizontal diffusivities. Vertical resolution is key to a proper representation of passive tracer propagation and - in the case of the Gulf of Mexico - contributes to both confining the tracer along the continental slope and limiting its vertical spreading. The choice of the tracer advection scheme is also important, with positive definiteness in the tracer concentration being achieved at the price of spurious mixing across density surfaces. In all cases, however, the diapycnal mixing coefficient derived from the model simulations overestimates the observed value, indicating an area where model improvement is needed.

Salinity maxima associated with some sub-surface water masses in the upper layers of the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Varadachari, V.V.R.; Murty, C.S.; Reddy, C.V.G.

The distribution of some sub-surface water masses in the western bay of Bengal during the south-west monsoon period is presented. Based on the salinity maxima and sigma t values the existence of waters of Persian Gulf and Red Sea origin could...

Diversity, distribution, and morphological deformities among living Foraminifera in hypersaline Salwa Bay, Saudi Arabia

Science.gov (United States)

Olalekan Amao, Abduljamiu; Kaminski, Michael

2016-04-01

The Arabian Gulf is considered a naturally stressed environment due to extremes of salinity and summer temperatures. Anthropogenic influences such as rapid urbanisation projects, maritime transport, and large numbers of desalination plants and oil-related activities compounds the problem. Foraminifera are known to be resilient under such stressful conditions. The purpose of our study is to document the foraminiferal diversity and abundance in the hypersaline Salwa Bay area, near the Saudi Arabian-Qatar Border. We expect the foraminiferal fauna in Salwa Bay to be adapted to extremes in salinity, and we wish to document any species that might be endemic or uniquely adapted to the area. Shannon-Wiener index, relative abundance, species richness, and the percentage of morphological deformities were determined for samples collected from the bay. Salwa Bay is the most saline extension of the Arabian Gulf with high salinity, water temperature and evaporation rate, which is attributed to slow flushing rates, coral reef barriers and higher residency time of the water. Environmental parameters measured at the time of collection were depth (10-110 cm), salinity (52.6-53.0) total dissolved solids (48.8-49.4 g/l), and temperature (27-27.6°C). The foraminiferal assemblages in Salwa Bay are dominated by porcelaneous foraminifera, which include Peneroplis pertusus, Peneroplis planatus, Coscinospira hemprichii and Coscinospira acicularis. The most common species across the sampled transect is Peneroplis pertusus. Hyaline species were also found, but agglutinated foraminifera are absent. Diversity in Salwa Bay is lower compared with localities that have "normal" salinity, and many of the foraminifera display conspicuous morphological deformities. Approximately 55% of the assemblage exhibits mild to severe deformities such as fusion of two adults or double tests, protuberance on the spiral side, abnormal arrangement of the chambers, abnormal shape of the proloculus and modification

137Cs and 210Pb distribution in Manila Bay sediment

International Nuclear Information System (INIS)

Sta. Maria, Efren J.; Madrid, Jordan F.; Olivares, Ryan U.; Bulos, Adelina DM; Dayaon, Jennyvi P.; Asa, Anie Day DC; Sombrito, Elvira Z.

2011-01-01

Two radionuclides were measured in surface sediment samples taken from geographically distributed sections of Manila Bay, namely cesium-137 ( 137 Cs) and lead-210 ( 210 Pb). Results indicated a noticeable change in the radioactivity concentration levels in sediments collected in 2005 and 2010, with a median concentration of 1.0 and 2.64 Bq kg -1 , respectively. Higher levels of 137 Cs radioactivity were measured in the northern and inner portion of the bay adjacent to major river systems, agricultural and highly industrialized urban areas. 137 Cs isotope increased in activity in most of the samples especially in the northwestern areas of Bataan and Pampanga with five times more than the activity from the first sampling measurements. Nevertheless, radioactivity concentrations observed in surface sediments along the bay are within the range of radioactivity in several areas monitored in the Northern Hemisphere. The country has been frequented by tropical cyclones and storms that have caused erosion, which may have introduced elevated material input in the bay. In addition, wind-driven circulation especially in the shallower areas of the bay is a possibility for the substantial sediment movement and accumulation along this coast. Conversely, areas with higher 137 Cs have lower values of 210 Pb. In an undisturbed environment, 210 Pb deposition values are assumed nearly constant. Hence, changes in the radioactivity concentration levels of these radionuclides can be an indicator of pollution input from land-based sources, sediment movement and reworking in the coastal areas. At present, there is very limited information on the radioactivity level of various radioisotopes in Manila Bay.The data obtained are benchmark values against which changes that will be occurring in the bay can be assessed. (author)

Systematic heat flow measurements across the Wagner Basin, northern Gulf of California

Science.gov (United States)

Neumann, Florian; Negrete-Aranda, Raquel; Harris, Robert N.; Contreras, Juan; Sclater, John G.; González-Fernández, Antonio

2017-12-01

A primary control on the geodynamics of rifting is the thermal regime. To better understand the geodynamics of rifting in the northern Gulf of California we systematically measured heat-flow across the Wagner Basin, a tectonically active basin that lies near the southern terminus of the Cerro Prieto fault. The heat flow profile is 40 km long, has a nominal measurement spacing of ∼1 km, and is collocated with a seismic reflection profile. Heat flow measurements were made with a 6.5-m violin-bow probe. Although heat flow data were collected in shallow water, where there are significant temporal variations in bottom water temperature, we use CTD data collected over many years to correct our measurements to yield accurate values of heat flow. After correction for bottom water temperature, the mean and standard deviation of heat flow across the western, central, and eastern parts of the basin are 220 ± 60, 99 ± 14, 889 ± 419 mW m-2, respectively. Corrections for sedimentation would increase measured heat flow across the central part of basin by 40 to 60%. We interpret the relatively high heat flow and large variability on the western and eastern flanks in terms of upward fluid flow at depth below the seafloor, whereas the lower and more consistent values across the central part of the basin are suggestive of conductive heat transfer. Moreover, heat flow across the central basin is consistent with gabbroic underplating at a depth of 15 km and suggests that continental rupture here has not gone to completion.

Spring migration of Northern Pintails from Texas and New Mexico, USA

Science.gov (United States)

Haukos, D.A.; Miller, M.R.; Orthmeyer, D.L.; Takekawa, John Y.; Fleskes, J.P.; Casazza, Michael L.; Perry, W.M.; Moon, J.A.

2006-01-01

We used satellite transmitters (platform transmitting terminals or PTTs) during 2002 and 2003 to document spring migration timing, routes, stopover sites, and nesting sites of adult female Northern Pintails (Anas acuta) from major wintering areas of the Gulf Coast (N = 20) and Playa Lakes Regions (PLR, N = 20) in Texas, and the Middle Rio Grande Valley, New Mexico (MRGV, N = 15). Some Pintails tagged in the MRGV continued movements into Mexico. Poor winter survival or PTT failure reduced sample size to 15 for PLR Pintails, 5 for Gulf Coast Pintails, and 11 for MRGV Pintails. Apparent winter survival was 66% lower for Texas Gulf Coast PTT-tagged Pintails than for those from the PLR and MRGV. Pintails from each area used different routes to their respective breeding grounds. PTT-tagged Pintails from the MRGV followed the Rio Grande Valley north to southern Colorado, before traveling on to the Dakotas and Canada or traveled northeast and joined the migration of PLR Pintails in Texas or Kansas. The latter made initial stops in Kansas, Nebraska, Colorado, or the Dakotas. Gulf Coast Pintails traveled through north-central Oklahoma or central Kansas. Pintails that had stopped first in Kansas or Nebraska tended to settle to nest in the United States. Wetland availability in the Prairie Pothole Region of the Northern Great Plains influenced nesting destinations of PTT-tagged Pintails, but individuals settled across a wide swath of northern North America. We did not detect any consistently-used spring staging areas. Therefore, negative impacts to any of the marked populations, or their wetland habitats, may have continental implications.

Role of upper ocean parameters in the genesis, intensification and tracks of cyclones over the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Maneesha, K.; Sadhuram, Y.; Prasad, K.V.S.R.

of high heat potential (>90 kj/cm2) in the western Gulf of Mexico (Goni et al. 2003, 2009; Shay et al. 2000). Further, Hurricanes Igor (tropical Atlantic) and Celia (Eastern North Pacific), Typhoon Megi (Western North Pacific) and Cyclone Phet (Arabian Sea... 2009/10 in the Gulf of Mexico and the southwestern Pacific Ocean, while there was an increase in the western Pacific Ocean, Arabian Sea and Bay of Bengal. All the above studies emphasize the importance of the UOHC in the genesis and intensification...

Pollution studies of Saronikos Gulf, Greece, by neutron activation analysis

International Nuclear Information System (INIS)

Grimanis, A.P.

1988-01-01

Neutron activation analysis (NAA) with its great sensitivity for a large number of elements has been widely used for marine environmental studies Saronikos Gulf receives combined domestic and industrial effluents of the grater Athens area through the Athens sewage outfall (ASO) at Keratsini Bay, which also receives wastes from discrete industrial sources including a fertilizer plant. Such discharges usually contain high concentrations of heavy metals, which can be dangerous to marine ecosystems and humans. This paper is a review of research and monitoring studies of toxic and other trace elements in marine organisms, seawater, and sediments of Saronikos Gulf by NAA performed over the last 15 yr. The objectives of these studies were (a) to find the fates and pathways of toxic and other trace elements, (b) to estimate the extent of pollution, and (c) to pinpoint and distinguish pollution sources

Monitoring of bird abundance and distribution at McKinley Bay and Hutchison Bay, Northwest Territories, 1981 to 1993

Energy Technology Data Exchange (ETDEWEB)

Cornish, B J; Dickson, D L

1994-04-01

McKinley Bay has been identified as a preferred site for a harbor to support oil and gas production in the Beaufort Sea. As the bay is a molting area for several species of diving duck, a study was initiated to monitor the effect of harbor development on birds using the bay. Baseline information on the natural annual fluctuations in the number of birds were collected for nine years at McKinley Bay and eight years at neighboring Hutchinson Bay, an area chosen as the control. The final report of the predevelopment phase of the monitoring study is presented, including results of the 1993 surveys and a summary of results of all years of surveys. There were significantly more diving ducks in McKinley Bay in early August 1990 to 1993, on average, than from 1981 to 1985. No statistically significant change in total diving ducks was noted at Hutchinson Bay. Numbers of species of divers varied substantially between years at the two bays but not to the same degree. Significantly more Pacific loons, red-throated loons, and northern pintails were recorded in the 1990-1993 surveys at McKinley Bay than in earlier surveys. Potential explanations for the large between-year fluctuations in diving duck numbers are discussed. The variations may be due to bird responses to changes in the physical environment or related to the limitations of the aerial survey techniques used. Because of the large natural fluctuations in numbers of molting diving ducks using these bays in early August, it will be difficult to detect future impacts of industrial disturbance, even when sources of survey bias are minimized. It is concluded that aerial surveys of molting diving ducks in the two bays are unsuitable for monitoring the effects of industrial development. 41 refs., 7 figs., 23 tabs.

Geophysical Data Define Boundaries and Sub-Regions of the Northern Gulf of Mexico Basin: Structural Histories and Causes are Hypothesized.

Science.gov (United States)

Kinsland, G. L.

2017-12-01

Within the last several years new types of geophysical data of the southern margin of the North American Craton and the Northern Gulf of Mexico Basin (NGoMB) have become available, e.g., results from the USArray experiment, high resolution satellite gravity data of the GoM itself and new heat flow data. These data when combined with previously existing geophysical data (gravity, magnetic and seismic) and shallow structural data offer new insights into the boundaries and sub-regions of the NGoMB. I offer hypotheses for the development of the structures of the buried crust and upper mantle which cause these features. Of particular interest might be my suggestion that the NGoMB might have extended in a southeasterly direction prior to the counter-clockwise rotation of the Yucatan Peninsula which ultimately resulted in the GoM.

Shelf break circulation in the Northern Gulf of Alaska

Energy Technology Data Exchange (ETDEWEB)

Niebauer, H.J.; Roberts, J.; Royer, T.C.

1981-05-20

Current observations from a mooring on the continental shelf near the shelf break in the Gulf of Alaska, with supporting hydrographic and metorological data, are discussed for the period 1976 to March 1977. The described features suggest strong influence by the cyclonic Alaska Gyre for the periods April--June 1976 and October 1976 to March 1977. From July--September 1976 there is evidence of current veering and rotation. It is hypothesized that these current fluctuations are eddies which are important in mixing processes across the shelf.

Land-Use and Land-Cover Change around Mobile Bay, Alabama from 1974-2008

Science.gov (United States)

Ellis, Jean; Spruce, Joseph P.; Swann, Roberta; Smooth, James C.

2009-01-01

This document summarizes the major findings of a Gulf of Mexico Application Pilot project led by NASA Stennis Space Center (SSC) in conjunction with a regional collaboration network of the Gulf of Mexico Alliance (GOMA). NASA researchers processed and analyzed multi-temporal Landsat data to assess land-use and land-cover (LULC) changes in the coastal counties of Mobile and Baldwin, AL between 1974 and 2008. Our goal was to create satellite-based LULC data products using methods that could be transferable to other coastal areas of concern within the Gulf of Mexico. The Mobile Bay National Estuary Program (MBNEP) is the primary end-user, however, several other state and local groups may benefit from the project s data products that will be available through NOAA-NCDDC s Regional Ecosystem Data Management program. Mobile Bay is a critical ecologic and economic region in the Gulf of Mexico and to the entire country. Mobile Bay was designated as an estuary of national significance in 1996. This estuary receives the fourth largest freshwater inflow in the United States. It provides vital nursery habitat for commercially and recreationally important fish species. It has exceptional aquatic and terrestrial bio-diversity, however, its estuary health is influenced by changing LULC patterns, such as urbanization. Mobile and Baldwin counties have experienced a population growth of 1.1% and 20.5% from 2000-2006. Urban expansion and population growth are likely to accelerate with the construction and operation of the ThyssenKrupp steel mill in the northeast portion of Mobile County. Land-use and land-cover change can negatively impact Gulf coast water quality and ecological resources. The conversion of forest to urban cover types impacts the carbon cycle and increases the freshwater and sediment in coastal waters. Increased freshwater runoff decreases salinity and increases the turbidity of coastal waters, thus impacting the growth potential of submerged aquatic vegetation (SAV

An Analysis of Thaumarchaeota Populations from the Northern Gulf of Mexico

Directory of Open Access Journals (Sweden)

Bradley B. Tolar

2013-04-01

Full Text Available We sampled Thaumarchaeota populations in the northern Gulf of Mexico, including shelf waters under the Mississippi River outflow plume that are subject to recurrent hypoxia. Data from this study allowed us to: 1 test the hypothesis that Thaumarchaeota would be abundant in this region; 2 assess phylogenetic composition of these populations for comparison with other regions; 3 compare the efficacy of quantitative PCR (qPCR based on primers for 16S rRNA genes (rrs with primers for genes in the ammonia oxidation (amoA and carbon fixation (accA, hcd pathways; 4 compare distributions obtained by qPCR with the relative abundance of Thaumarchaeota rrs in pyrosequenced libraries; 5 compare Thaumarchaeota distributions with environmental variables to help us elucidate the factors responsible for the distributions; 6 compare the distribution of Thaumarchaeota with Nitrite-Oxidizing Bacteria (NOB to gain insight into the coupling between ammonia and nitrite oxidation. We found up to 108 copies L-1 of Thaumarchaeota rrs in our samples (up to 40% of prokaryotes by qPCR, with maximum abundance in slope waters at 200-800 m. Thaumarchaeota rrs were also abundant in pyrosequenced libraries and their relative abundance correlated well with values determined by qPCR (r2=0.82. Thaumarchaeota populations were strongly stratified by depth. Canonical correspondence analysis using a suite of environmental variables explained 92% of the variance in qPCR-estimated gene abundances. Thaumarchaeota rrs abundance was correlated with salinity and depth, while accA abundance correlated with fluorescence and pH. Correlations of Archaeal amoA abundance with environmental variables were primer-dependent, suggesting differential responses of sub-populations to environmental variables. Bacterial amoA was at the limit of qPCR detection in most samples. NOB and Euryarchaeota rrs were found in the pyrosequenced libraries; NOB distribution was correlated with that of Thaumarchaeota (r2=0.49

Bay of Fundy

Science.gov (United States)

2006-01-01

The highest tides on Earth occur in the Minas Basin, the eastern extremity of the Bay of Fundy, Nova Scotia, Canada, where the tide range can reach 16 meters when the various factors affecting the tides are in phase. The primary cause of the immense tides of Fundy is a resonance of the Bay of Fundy-Gulf of Maine system. The system is effectively bounded at this outer end by the edge of the continental shelf with its approximately 40:1 increase in depth. The system has a natural period of approximately 13 hours, which is close to the 12h25m period of the dominant lunar tide of the Atlantic Ocean. Like a father pushing his daughter on a swing, the gentle Atlantic tidal pulse pushes the waters of the Bay of Fundy-Gulf of Maine basin at nearly the optimum frequency to cause a large to-and-fro oscillation. The greatest slosh occurs at the head (northeast end) of the system. The high tide image (top) was acquired April 20, 2001, and the low tide image (bottom) was acquired September 30, 2002. The images cover an area of 16.5 by 21 km, and are centered near 64 degrees west longitude and 45.5 degrees north latitude. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying

Applying Benthic Index of Biotic Integrity in a soft bottom ecosystem in North of the Persian Gulf.

Science.gov (United States)

Doustshenas, B; Savari, A; Nabavi, S M B; Kochanian, P; Sadrinasab, M

2009-06-15

In this study, the Chesapeake Bay Benthic Index of Biotic Integrity (B-IBI) was selected in an attempt to describe ecological health of soft bottom channels (Khowr-e Musa) in North of the Persian Gulf. Most of study area was found to be in degraded or severely degraded conditions. B-IBI scores were ranged between 1 and 3.86. Comparison ofmacrobenthos abundance and organic content between two developmental periods showed significant difference (p dredging. Choice of suitable management plans and metric controls could help to the salvage of the largest tidal channel complex in Persian Gulf.

Seasonal evolution of cholorophyll-a and cyanobacteria (Prochlorococcus and Synechococcus on the northeast continental shelf of the Gulf of Cádiz: relation to thermohaline and nutrients fields

Directory of Open Access Journals (Sweden)

Eleonora Anfuso

2013-01-01

Full Text Available The seasonal evolution of nutrients, chlorophyll-a (chl-a and cyanobacteria (Synechococcus and Prochlorococcus on the northeast continental shelf of the Gulf of Cádiz was observed during four cruises in summer and autumn 2006 and winter and spring 2007. Samples were collected to determine the distribution of chl-a and cyanobacteria abundance and to analyse their coupling with thermohaline and chemical properties in the gulf region. Surface nutrient distributions showed clear seasonal variability. Maximum levels were recorded for the entire study region during winter due to winter mixing and the strong influence of the Guadalquivir River and Bay of Cádiz outflow. Maximum chl-a levels were reached during spring for the entire region and for the entire water column. Minimum values of chl-a were observed during summer, under prevailing oligotrophic conditions, and winter when in spite of relatively high nutrient concentrations, phytoplankton growth was probably light-limited. The distribution of both cyanobacteria populations also varied seasonally in association with the oceanographic conditions. Prochlorococcus maximum cell abundance was observed at the sea surface during the four cruises, except in the northern region during summer. However, Synechococcus showed a maximum concentration at the sea surface in autumn and winter and at the subsurface chlorophyll maximum in autumn and spring.

Genetic differentiation of the Kittlitz's Murrelet Brachyramphus brevirostris in the Aleutian Islands and Gulf of Alaska

Science.gov (United States)

Birt, T.P.; Mackinnon, D.; Piatt, John F.; Friesen, Vicki L.

2011-01-01

Information about the distribution of genetic variation within and among local populations of the Kittlitz's Murrelet Brachyramphus brevirostris is needed for effective conservation of this rare and declining species. We compared variation in a 429 base pair fragment of the mitochondrial control region and 11 microsatellite loci among 53 Kittlitz's Murrelets from three sites in the western Aleutian Islands (Attu Island) and Gulf of Alaska (Glacier Bay and Kachemak Bay). We found that birds in these two regions differ genetically in three assessments: (1) global and pairwise indices of genetic differentiation were significantly greater than zero, (2) mitochondrial haplotypes differed by a minimum of nine substitutions, and (3) molecular assignments indicated little gene flow between regions. The data suggest that birds in these regions have been genetically isolated for an extended period. We conclude that Kittlitz's Murrelets from Attu Island and from the Gulf of Alaska represent separate evolutionarily significant units, and should be treated as such for conservation. Genetic data for Kittlitz's Murrelets from the remainder of the breeding range are urgently needed.

Evaluation of Pollution Level in Zolotoy Rog Bay (Peter the Great Gulf, the Sea of Japan)

Science.gov (United States)

Kazachkova, Y.; Lazareva, L.; Petukhov, V.

2017-11-01

The results of the hydrochemical research of water and bottom sediments of the Zolotoy Rog Bay in July 2015 are presented below. It is shown that, as a result of a large amount of polluted sewage entering The Zolotoy Rog Bay, the concentrations of organic substances (BOD5) and petroleum hydrocarbons in the water exceed the MPC. The concentrations of heavy metals in soils exceed both the background level and the level of permissible values. As a result of the calculation of the bottom accumulation (CBA) coefficient for oil hydrocarbons, the situation in the Zolotoy Rog Bay can be classified as an ecological disaster. According to the total pollution index (Zc) of heavy metals, the bottom sediments of the Zolotoy Rog Bay are characterized as strongly and very strongly polluted.

Tampa Bay as a model estuary for examining the impact of human activities on biogeochemical processes: an introduction

Science.gov (United States)

Swarzenski, Peter W.; Baskaran, Mark; Henderson, Carl S.; Yates, Kim

2007-01-01

Tampa Bay is a shallow, Y-shaped coastal embayment that is located along the center of the Florida Platform – an expansive accumulation of Cretaceous–Tertiary shallow-water carbonates and evaporites that were periodically exposed during glacio–eustatic sea level fluctuations. As a consequence, extensive karstification likely had a controlling impact on the geologic evolution of Tampa Bay. Despite its large aerial size (∼ 1000 km2), Tampa Bay is relatively shallow (mean depth = 4 m) and its watershed (6700 km2) is among the smallest in the Gulf of Mexico. About 85% of all freshwater inflow (mean = 63 m3 s-1) to the bay is carried by four principal tributaries (Orlando et al., 1993). Groundwater makes up an important component of baseflow of these coastal streams and may also be important in delivering nutrients and other constituents to the bay proper by submarine groundwater discharge.

Carbonate deposition and salt diapirism during the Cretaceous in the Persian Gulf, offshore Iran

OpenAIRE

U. P. Baaske; M. Mutti; F. Baioni; R. Buonaguro; G. Bertozzi; M. A. Naini; C. M. Krawczyk; P. Kukla; R. Littke; H. Stollhofen; D. Schwarzer;  

2004-01-01

The Cretaceous deposits in the Persian Gulf area are part of one of the largest hydrocarbon systems in the world. The stratigraphic evolution of the northern part of the Gulf is, however, poorly constrained. Seismic data from offshore Iran reveal that the shallow water deposition is marked by topographic features like the NNE-SSW trending Qatar-Fars-Arch and salt-related structures (diapirs and salt walls) of smaller scale. These structures were active during the Cretaceous. To examine the ef...

An analysis of the relationship between drought events and mangrove changes along the northern coasts of the Pe rsian Gulf and Oman Sea

Science.gov (United States)

Mafi-Gholami, Davood; Mahmoudi, Beytollah; Zenner, Eric K.

2017-12-01

Relating the changes of mangrove forests to spatially explicit reductions in rainfall amounts and increases in drought occurrences is a prerequisite for improving the effectiveness and success of mangrove forest conservation programs. To this end, we investigated the relationship between drought events (quantified using the Standardized Precipitation Index [SPI]) and changes in area and canopy cover of mangrove forests on the northern coast of the Persian Gulf and the Oman Sea using satellite imagery and long-term annual rainfall data over a period of 30 years (1986-2016). Statistical analyses revealed 1998 as the year marking the most significant change-point in the mean annual rainfall values in the catchments and mangroves, after which average SPI values consistently remained at lower levels. In the period of 1998-2016, decreases in the mean annual rainfall and increases in the severity of droughts differed spatially and were greater in the catchments and mangroves on the coasts of the Oman Sea than the coasts of the Persian Gulf. These spatially explicit results were closely mirrored by the mangrove response, with differential in reductions in mangrove areas and canopy cover that corresponded closely with the spatial distribution of drought intensities in the different parts of the coasts, with correlation coefficients ≥0.89 for the different coastal regions.

Influence of net freshwater supply on salinity in Florida Bay

Science.gov (United States)

Nuttle, William K.; Fourqurean, James W.; Cosby, Bernard J.; Zieman, Joseph C.; Robblee, Michael B.

2000-01-01

An annual water budget for Florida Bay, the large, seasonally hypersaline estuary in the Everglades National Park, was constructed using physically based models and long‐term (31 years) data on salinity, hydrology, and climate. Effects of seasonal and interannual variations of the net freshwater supply (runoff plus rainfall minus evaporation) on salinity variation within the bay were also examined. Particular attention was paid to the effects of runoff, which are the focus of ambitious plans to restore and conserve the Florida Bay ecosystem. From 1965 to 1995 the annual runoff from the Everglades into the bay was less than one tenth of the annual direct rainfall onto the bay, while estimated annual evaporation slightly exceeded annual rainfall. The average net freshwater supply to the bay over a year was thus approximately zero, and interannual variations in salinity appeared to be affected primarily by interannual fluctuations in rainfall. At the annual scale, runoff apparently had little effect on the bay as a whole during this period. On a seasonal basis, variations in rainfall, evaporation, and runoff were not in phase, and the net freshwater supply to the bay varied between positive and negative values, contributing to a strong seasonal pattern in salinity, especially in regions of the bay relatively isolated from exchanges with the Gulf of Mexico and Atlantic Ocean. Changes in runoff could have a greater effect on salinity in the bay if the seasonal patterns of rainfall and evaporation and the timing of the runoff are considered. One model was also used to simulate spatial and temporal patterns of salinity responses expected to result from changes in net freshwater supply. Simulations in which runoff was increased by a factor of 2 (but with no change in spatial pattern) indicated that increased runoff will lower salinity values in eastern Florida Bay, increase the variability of salinity in the South Region, but have little effect on salinity in the Central

Seasonal and inter-annual variability of surface circulation in the Bay of Bengal from TOPEX/Poseidon altimetry

Digital Repository Service at National Institute of Oceanography (India)

Somayajulu, Y.K.; Murty, V.S.N.; Sarma, Y.V.B.

- west monsoon period, (Fig. 5c) reflected the Fig.3. Variation of (a) Southern Oscillation Index (SOI) and (b) SST anomaly(Del. SST) in the Western Equatorial Pacific (WEP, NINO4, 51N–51S; 1601E–1501W) during the 5-year period (January1993–December 1997.... Inter-annual variation of SSH anomalyat selected locations: (a) off Sumatra (EEIO), (b) southern bay(SB), (c) eastern bay (EB), (d) northern bay(NB), (e) western bay(WB), and (f) central bay(CB). SST anomaly(Del. SST) is shown bydashed line in (a). Y...

Persistence of Gulf War oil versus intertidal morphology and sediments - one year later

International Nuclear Information System (INIS)

Montello, T.M.; Hayes, M.O.; Michel, J.; Al-Momen, A.H.; Al-Mansi, A.M.; Aurand, D.V.

1993-01-01

A study of the persistence of oil in the intertidal habitats of the Saudi Arabian coast was carried out one year after the Gulf war spill in conjunction with the National Oceanic and Atmospheric Administration ship Mt. Mitchell's ROPME Sea Cruise. A total of 10 kilometers of transects were surveyed at 20 stations, representing heavily oiled sheltered beaches, tidal flats, algal mats, halophyte saltmarshes, and mangroves at the heads of bays

Characteristics of Tides in the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Sindhu, B.; Unnikrishnan, A.S.

gradually from the northern end to the 2.5°N and decreases towards southern boundary. The co-tidal and co-range charts of M2 and S2 tidal constituents also show the presence of two degenerate amphidromic points in the head bay. A virtual amphidromic point...

Spatial Variation of Diapycnal Diffusivity Estimated From Seismic Imaging of Internal Wave Field, Gulf of Mexico

OpenAIRE

Dickinson, Nicholas; White, Nicholas Jeremiah; Caulfield, Colm-cille Patrick

2017-01-01

Bright reflections are observed within the upper 1000~m of the water column along a seismic reflection profile that traverses the northern margin of the Gulf of Mexico. Independent hydrographic calibration demonstrates that these reflections are primarily caused by temperature changes associated with different water masses that are entrained into the Gulf along the Loop Current. The internal wave field is analyzed by automatically tracking 1171 reflections, each of which is greater th...

Occurrence of @iNeogloboquadrina pachyderma@@ new subspecies in the shelf-slope sediments of northern Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Setty, M.G.A.P.

~'N in the Bay of Bengal. Studies of hydrological conditions in the Indian Ocean reveal that the Subtropical Subsurface Water Mass is traceable as far north as the Gulf of Aden, and the Indian Ocean Deep Bottom Water Mass originating in the deepest...

Importance of the Gulf of Aqaba for the formation of bottom water in the Red Sea

Science.gov (United States)

Plähn, Olaf; Baschek, Burkard; Badewien, Thomas H.; Walter, Maren; Rhein, Monika

2002-08-01

Conductivity-temperature-depth tracer and direct current measurements collected in the northern Red Sea in February and March 1999 are used to study the formation of deep and bottom water in that region. Historical data showed that open ocean convection in the Red Sea can contribute to the renewal of intermediate or deep water but cannot ventilate the bottom water. The observations in 1999 showed no evidence for open ocean convection in the Red Sea during the winter 1998/1999. The overflow water from the Gulf of Aqaba was found to be the densest water mass in the northern Red Sea. An anomaly of the chlorofluorocarbon component CFC-12 observed in the Gulf of Aqaba and at the bottom of the Red Sea suggests a strong contribution of this water mass to the renewal of bottom water in the Red Sea. The CFC data obtained during this cruise are the first available for this region. Because of the new signal, it is possible for the first time to subdivide the deep water column into deep and bottom water in the northern Red Sea. The available data set also shows that the outflow water from the Gulf of Suez is not dense enough to reach down to the bottom of the Red Sea but was found about 250 m above the bottom.

The Gulf of Carpentaria heated Torres Strait and the Northern Great Barrier Reef during the 2016 mass coral bleaching event

Science.gov (United States)

Wolanski, E.; Andutta, F.; Deleersnijder, E.; Li, Y.; Thomas, C. J.

2017-07-01

The 2015/16 ENSO event increased the temperature of waters surrounding northeast Australia to above 30 °C, with large patches of water reaching 32 °C, for over two months, which led to severe bleaching of corals of the Northern Great Barrier Reef (NGBR). This study provides evidence gained from remote-sensing data, oceanographic data and oceanographic modeling, that three factors caused this excessive heating, namely: 1) the shutdown of the North Queensland Coastal Current, which would otherwise have flushed and cooled the Northern Coral Sea and the NGBR through tidal mixing 2) the advection of warm (>30 °C) water from the Gulf of Carpentaria eastward through Torres Strait and then southward over the NGBR continental shelf, and 3) presumably local solar heating. The eastward flux of this warm water through Torres Strait was driven by a mean sea level difference on either side of the strait that in turn was controlled by the wind, which also generated the southward advection of this warm water onto the NGBR shelf. On the NGBR shelf, the residence time of this warm water was longer inshore than offshore, and this may explain the observed cross-shelf gradient of coral bleaching intensity. The fate of the Great Barrier Reef is thus controlled by the oceanography of surrounding seas.

Organochlorine contaminants in seven species of Arctic seabirds from northern Baffin Bay

International Nuclear Information System (INIS)

Buckman, Andrea H.; Norstrom, Ross J.; Hobson, Keith A.; Karnovsky, Nina J.; Duffe, Jason; Fisk, Aaron T.

2004-01-01

Organochlorine contaminants (OCs) were determined in liver and fat of seven species of seabirds (Alle alle, Uria lomvia, Cepphus grylle, Rissa tridactyla, Pagophila eburnea, Larus hyperboreus, and Fulmaris glacialis) collected in May/June 1998 from the Northwater Polynya in northern Baffin Bay. OC concentrations ranged over an order of magnitude between seabird species and OC groups, with PCBs having the highest concentrations followed by DDT, chlordane, HCH and ClBz. Positive relationships between δ 15 N (estimator of trophic level) and OC concentrations (lipid basis) were found for all OC groups, showing that trophic position and biomagnification significantly influence OC concentrations in Arctic seabirds. Concentrations of a number of OCs in particular species (e.g., HCH in P. eburnean) were lower than expected based on δ 15 N and was attributed to biotransformation. P. eburnea and F. glacialis, which scavenge, and R. tridactyla, which migrate from the south, were consistently above the δ 15 N-OC regression providing evidence that these variables can elevate OC concentrations. Stable isotope measurements in muscle may not be suitable for identifying past scavenging events by seabirds. OC relative proportions were related to trophic position and phylogeny, showing that OC biotransformation varies between seabird groups. Trophic level, migration, scavenging and biotransformation all play important roles in the OCs found in Arctic seabirds. - Concentrations of organochlorides in high Arctic seabirds are influenced by trophic level, migration, scavenging and biotransformation

Guide to Common Tidal Marsh Invertebrates of the Northeastern Gulf of Mexico.

Science.gov (United States)

Heard, Richard W.

The major groups of marine and estuarine macroinvertebrates of the tidal marshes of the northern Gulf of Mexico are described in this guide for students, taxonomists and generalists. Information on the recognition characteristics, distribution, habitat, and biology of salt marsh species from the coelenterate, annelid, mollusk and arthropod phyla…

Sea surface temperature and Ekman transport in the Persian Gulf

Directory of Open Access Journals (Sweden)

E. H.

2002-12-01

Full Text Available   The wind drift motion of the water which is produced by the stress of the wind exerted upon the surface of the ocean is described by Ekmans theory (1905. Using the mean monthly values for the wind stress and SST, seasonal Ekman transport for the Persian Gulf was computed and contoured. The geostrophic winds have combined with the SST to estimate the effect of cooling due to Ekman transport of colder northern waters and inflow from the Oman Sea. The monthly SST mainly obtained from the 10 10 grided data of Levitus atlas and Hormuz Cruis Experiment for 1997.   Analyses show a NW to SE Ekman transport due to wind stress and significant interannual variability of SST on sea surface in the Persian Gulf. The seasonal variation of SST shows a continental pattern due to severe interaction between the land and sea. But these variations somehow moderates because of Ekman transport in Persian Gulf.

Historical occurrences of polybrominated diphenyl ethers and polychlorinated biphenyls in Manila Bay, Philippines, and in the upper Gulf of Thailand.

Science.gov (United States)

Kwan, Charita S; Takada, Hideshige; Boonyatumanond, Ruchaya; Kato, Yoshihisa; Mizukawa, Kaoruko; Ito, Maki; Dung, Le Quang; Zakaria, Mohamad Pauzi; Santiago, Evangeline C

2014-02-01

Historical trends of the accumulation of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in a typical tropical Asian environment were investigated using radio-dated sediment cores from Manila Bay, the Philippines and from the upper Gulf of Thailand. Vertical profiles indicated earlier usage of PCBs than of PBDEs which coincided with their industrial production. The increasing concentrations of total PBDEs and PCBs toward the surface suggested an increased consumption of PBDEs; and possible leakage of PCBs from old machineries into the aquatic environment in recent years. Current input of PCBs to the catchment of Manila Bay was supported by the analyses of air samples and plastic resin pellets. The vertical profiles of total PBDEs in the cores (i.e., rapidly increasing concentrations corresponding to the mid-1980s until mid-1990s, followed by a decrease until the early 2000s, and increasing again toward the surface) likely corresponded to the rapid economic growth in Asia in the 1990s, the Asian financial crisis in 1997, and the economic recovery since early 2000s. BDE-209 was predominant especially on the surface layers. BDEs 47 and 99 generally decreased toward the surface, reflecting the phase-out of the technical penta-PBDE products and the regulation by the Stockholm Convention in recent years. Increasing ratios of BDE-202/209, 206/209, 207/209 and decreasing % of BDE-209 down the core layers may provide evidence for the anaerobic debromination of BDE-209 in the sediment cores. Inventories in ng/cm(2) of total PCBs were higher than total PBDEs (92 vs. 34 and 47 vs. 11 in the Philippines; 47 vs. 33 in Thailand). However, the doubling times indicated faster accumulation of total PBDEs (6-7 years) and BDE-209 (6-7.5 years) than of PCBs (8-11 years). Furthermore, the temporal increase in BDE-209 was comparable to or faster than those reported in other water bodies around the world. © 2013.

Transport and inventory of mercury from point sources in Haifa Bay. Final report for the period 15 April 1995 - 15 April 1996

International Nuclear Information System (INIS)

Herut, B.

1996-09-01

The purpose of this study was to examine the main sinks and transport mechanisms of anthropogenic mercury in the Northern part of Haifa Bay. Haifa Bay is located at the Northern Mediterranean coast of Israel. Mercury has been constantly introduced into the Northern part of the Bay since the opening of a chlor-alkali plant in 1956. Between 1975-79 the flux was drastically reduced after installation of pollution abatements and in 1981 it was reduced further to its present level of 30 kg yr- 1 . The total calculated amount of mercury introduced to the Bay during the last 38 years is about 19,300 kg. Mercury inventory in sediments of the inner Northern part of Haifa bay was calculated by backwards extrapolation of the total amount of mercury which could have been present in the top 50 cm sediments if only accumulation processes occurred. The amount trapped in the sediments accounted for only approximately 10% of the total estimated amount of anthropogenic mercury. Part of the missing mercury settled in the sediments of the outer Bay and a significant part was transported seaward by mercury-laden particles and as resuspended near shore sediments. Indeed, relatively high concentrations of suspended particulate matter (1-3 mg 1- 1 ) with mercury concentrations (1-10 ug g- 1 ) of one order of magnitude higher than in the surface sediments were sampled in the area opposite the chlor-alkali plant. The total amount of mercury in the samples was measured by cold vapor atomic absorption spectrometry on a Coleman Mercury Analyser MAS-50A. 2 figs

Characterization of sea floor in Gulf of Mexico

Energy Technology Data Exchange (ETDEWEB)

McGregor, B.A.; Kenyon, N.H.; Schlee, J.S.; Mattick, R.e.; Twichell, D.C.

1986-05-01

In 1985, the US Geological Survey (USGS) conducted a mapping program in the Gulf of Mexico. Using the GLORIA (Geologic Long-Range Inclined Asdic) side-scan sonar system of the Institute of Oceanographic Sciences, USGS mapped approximately 90,000 nmi/sup 2/ of sea floor in the central and western Gulf of Mexico, seaward of the shelf edge. The Sigsbee Escarpment, the seaward edge of a salt front that extends from the western gulf to just west of the Mississippi Canyon, is marked by piles of debris along its base, and is breached by several submarine channels. One such meandering channel can be traced from the shelf edge, through the maze of diapirs on the slope, and out across the Sigsbee Abyssal Plain. This continuous transport pathway indicates the interaction of salt tectonics on sediment pathways and distribution. Numerous bed forms seaward of the Sigsbee Escarpment suggest that strong bottom currents are present. The northern gulf has three major submarine fans, each with different surface morphologies. The Rio Grande Fan has a braided channel system. The Mississippi Fan has a main channel that can be traced for approximately 100 km across the midfan, but most of the surface of the upper and midfan as well as the channel are buried by submarine slides or debris flows. Desoto Canyon Fan also has a continuous channel that has been filled or overrun in places by massive debris flows. Based on the sonographs, mass wasting appears to be an important process in distributing sediments in the deep water of the central gulf.

Probabilistic assessment of erosion and flooding risk in the northern Gulf of Mexico

Science.gov (United States)

Wahl, Thomas; Plant, Nathaniel G.; Long, Joseph W.

2016-05-01

We assess erosion and flooding risk in the northern Gulf of Mexico by identifying interdependencies among oceanographic drivers and probabilistically modeling the resulting potential for coastal change. Wave and water level observations are used to determine relationships between six hydrodynamic parameters that influence total water level and therefore erosion and flooding, through consideration of a wide range of univariate distribution functions and multivariate elliptical copulas. Using these relationships, we explore how different our interpretation of the present-day erosion/flooding risk could be if we had seen more or fewer extreme realizations of individual and combinations of parameters in the past by simulating 10,000 physically and statistically consistent sea-storm time series. We find that seasonal total water levels associated with the 100 year return period could be up to 3 m higher in summer and 0.6 m higher in winter relative to our best estimate based on the observational records. Impact hours of collision and overwash—where total water levels exceed the dune toe or dune crest elevations—could be on average 70% (collision) and 100% (overwash) larger than inferred from the observations. Our model accounts for non-stationarity in a straightforward, non-parametric way that can be applied (with little adjustments) to many other coastlines. The probabilistic model presented here, which accounts for observational uncertainty, can be applied to other coastlines where short record lengths limit the ability to identify the full range of possible wave and water level conditions that coastal mangers and planners must consider to develop sustainable management strategies.

Probabilistic assessment of erosion and flooding risk in the northern Gulf of Mexico

Science.gov (United States)

Plant, Nathaniel G.; Wahl, Thomas; Long, Joseph W.

2016-01-01

We assess erosion and flooding risk in the northern Gulf of Mexico by identifying interdependencies among oceanographic drivers and probabilistically modeling the resulting potential for coastal change. Wave and water level observations are used to determine relationships between six hydrodynamic parameters that influence total water level and therefore erosion and flooding, through consideration of a wide range of univariate distribution functions and multivariate elliptical copulas. Using these relationships, we explore how different our interpretation of the present-day erosion/flooding risk could be if we had seen more or fewer extreme realizations of individual and combinations of parameters in the past by simulating 10,000 physically and statistically consistent sea-storm time series. We find that seasonal total water levels associated with the 100 year return period could be up to 3 m higher in summer and 0.6 m higher in winter relative to our best estimate based on the observational records. Impact hours of collision and overwash—where total water levels exceed the dune toe or dune crest elevations—could be on average 70% (collision) and 100% (overwash) larger than inferred from the observations. Our model accounts for non-stationarity in a straightforward, non-parametric way that can be applied (with little adjustments) to many other coastlines. The probabilistic model presented here, which accounts for observational uncertainty, can be applied to other coastlines where short record lengths limit the ability to identify the full range of possible wave and water level conditions that coastal mangers and planners must consider to develop sustainable management strategies.

A survey of cardinalfish (Apogonidae) of Antsira- nana Bay, northern ...

African Journals Online (AJOL)

were observed including one species not previously recorded in Madagascar ... against existing records. Overall the ... tions include oceanic currents, temperature, depth, disturbance .... mentation as a result of terrestrial activities occurs within the bay ... of particularly abundant species in samples (Clarke and Gorley. 2006).

Scientific Guidance for Rehabilitation of the Chesapeake Bay Ecosystem under the Changing Climate.

Science.gov (United States)

Boesch, D. F.; Johnson, Z. P.; Li, M.

2017-12-01

While the Chesapeake Bay is an estuary and not a marginal sea on the scale of the Baltic Sea or the Gulf of Mexico, it has a complex set of environmental issues and multiple political jurisdictions such that it can serve as a test bed for science-informed management in larger marine systems. In particular, the Chesapeake Bay possesses a relatively advanced effort to ameliorate eutrophication, reduce toxic stresses, rehabilitate critical habitats, and sustainably utilized resources. Furthermore, both scientists and managers are addressing these challenges while now beginning to incorporate the effects of changes in temperature, precipitation and runoff, sea level, ocean boundary conditions, and pH. Increases in temperature and sea level are already apparent and future conditions can be estimated from global model projections, although sea level and ocean exchanges are also affected by variations in Gulf Stream flows and mesoscale climate. Changes in the volume, seasonality and variability in freshwater delivery from the multiple rivers discharging to the bay are harder to project with confidence, but may have pervasive consequences for circulation, reducing nutrient loads to ameliorate eutrophication, biogeochemical processes, and biotic distributions and dynamics. Science is now challenged to inform multiple adaptation strategies, including minimizing the vulnerability of humans and infrastructure, sustaining important tidal wetlands, managing sediment resources, sustaining living resources, redefining achievable ecosystem rehabilitation goals, and achieving shifting goals for nutrient load reductions. At the same time, science will also have to identify effective means to meet these challenges while also reducing greenhouse gas emissions.

Seabird colonies in the Melville Bay, Northwest Greenland

DEFF Research Database (Denmark)

Boertmann, David; Huffeldt, Nicholas Per

This report describes the results of a survey for breeding and colonial seabirds in a hitherto un-surveyed area of Northwest Greenland - the Melville Bay. The results shall be included as background data for oil spill sensitivity mapping, preparation of environmental impact assessments of petroleum...... activities in Baffin Bay and for the regulation (by the Greenland government) of petroleum activities. The survey showed, that compared to other coasts of West Greenland, the Melville Bay holds only few breeding colonies and low numbers of breeding seabirds. The most widespread and numerous species...... is the black guillemot followed by the glaucous gull. However, one colony is of national significance – Sabine Øer, with high numbers of breeding Arctic terns and Sabine’s gulls. Other noteworthy observations were puffins on Thom Ø and many new Iceland gull colonies that extended the known northern breeding...

Red Oak Research and Demonstration Area in Phelps Township, North Bay, Ontario-2004 to 2005

Science.gov (United States)

Dave Deugo; Andrée Morneault; Dianne Othmer; Megan Smith; Al Stinson; Murray Woods; Ian Kovacs; Ian Aho; Bill Parker; Rob Baker; Marinus Verwey; Guylaine Thauvette; Don Willis; Jeff Dech

2006-01-01

In July 2004, a large stand of red oak (Quercus rubra) was harvested in Phelps Township, North Bay District, North Bay, Ontario using the uniform shelterwood system. Most of the stand was harvested to retain 40 percent crown closure, while a very small portion was harvested to retain 70 percent crown closure. During tree marking, an active Northern...

Oil Spill Detection along the Gulf of Mexico Coastline based on Airborne Imaging Spectrometer Data

Science.gov (United States)

Arslan, M. D.; Filippi, A. M.; Guneralp, I.

2013-12-01

The Deepwater Horizon oil spill in the Gulf of Mexico between April and July 2010 demonstrated the importance of synoptic oil-spill monitoring in coastal environments via remote-sensing methods. This study focuses on terrestrial oil-spill detection and thickness estimation based on hyperspectral images acquired along the coastline of the Gulf of Mexico. We use AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) imaging spectrometer data collected over Bay Jimmy and Wilkinson Bay within Barataria Bay, Louisiana, USA during September 2010. We also employ field-based observations of the degree of oil accumulation along the coastline, as well as in situ measurements from the literature. As part of our proposed spectroscopic approach, we operate on atmospherically- and geometrically-corrected hyperspectral AVIRIS data to extract image-derived endmembers via Minimum Noise Fraction transform, Pixel Purity Index-generation, and n-dimensional visualization. Extracted endmembers are then used as input to endmember-mapping algorithms to yield fractional-abundance images and crisp classification images. We also employ Multiple Endmember Spectral Mixture Analysis (MESMA) for oil detection and mapping in order to enable the number and types of endmembers to vary on a per-pixel basis, in contast to simple Spectral Mixture Analysis (SMA). MESMA thus better allows accounting for spectral variabiltiy of oil (e.g., due to varying oil thicknesses, states of degradation, and the presence of different oil types, etc.) and other materials, including soils and salt marsh vegetation of varying types, which may or may not be affected by the oil spill. A decision-tree approach is also utilized for comparison. Classification results do indicate that MESMA provides advantageous capabilities for mapping several oil-thickness classes for affected vegetation and soils along the Gulf of Mexico coastline, relative to the conventional approaches tested. Oil thickness-mapping results from MESMA

Storm-driven sediment transport in Massachusetts Bay

Science.gov (United States)

Warner, J.C.; Butman, B.; Dalyander, P.S.

2008-01-01

Massachusetts Bay is a semi-enclosed embayment in the western Gulf of Maine about 50 km wide and 100 km long. Bottom sediment resuspension is controlled predominately by storm-induced surface waves and transport by the tidal- and wind-driven circulation. Because the Bay is open to the northeast, winds from the northeast ('Northeasters') generate the largest surface waves and are thus the most effective in resuspending sediments. The three-dimensional oceanographic circulation model Regional Ocean Modeling System (ROMS) is used to explore the resuspension, transport, and deposition of sediment caused by Northeasters. The model transports multiple sediment classes and tracks the evolution of a multilevel sediment bed. The surficial sediment characteristics of the bed are coupled to one of several bottom-boundary layer modules that calculate enhanced bottom roughness due to wave-current interaction. The wave field is calculated from the model Simulating WAves Nearshore (SWAN). Two idealized simulations were carried out to explore the effects of Northeasters on the transport and fate of sediments. In one simulation, an initially spatially uniform bed of mixed sediments exposed to a series of Northeasters evolved to a pattern similar to the existing surficial sediment distribution. A second set of simulations explored sediment-transport pathways caused by storms with winds from the northeast quadrant by simulating release of sediment at selected locations. Storms with winds from the north cause transport southward along the western shore of Massachusetts Bay, while storms with winds from the east and southeast drive northerly nearshore flow. The simulations show that Northeasters can effectively transport sediments from Boston Harbor and the area offshore of the harbor to the southeast into Cape Cod Bay and offshore into Stellwagen Basin. This transport pattern is consistent with Boston Harbor as the source of silver found in the surficial sediments of Cape Cod Bay and

The Red Sea and Gulf of Aden Basins

Science.gov (United States)

Bosworth, William; Huchon, Philippe; McClay, Ken

2005-10-01

We here summarize the evolution of the greater Red Sea-Gulf of Aden rift system, which includes the Gulfs of Suez and Aqaba, the Red Sea and Gulf of Aden marine basins and their continental margins, and the Afar region. Plume related basaltic trap volcanism began in Ethiopia, NE Sudan (Derudeb), and SW Yemen at ˜31 Ma, followed by rhyolitic volcanism at ˜30 Ma. Volcanism thereafter spread northward to Harrats Sirat, Hadan, Ishara-Khirsat, and Ar Rahat in western Saudi Arabia. This early magmatism occurred without significant extension, and continued to ˜25 Ma. Much of the Red Sea and Gulf of Aden region was at or near sea level at this time. Starting between ˜29.9 and 28.7 Ma, marine syn-tectonic sediments were deposited on continental crust in the central Gulf of Aden. At the same time the Horn of Africa became emergent. By ˜27.5-23.8 Ma a small rift basin was forming in the Eritrean Red Sea. At approximately the same time (˜25 Ma), extension and rifting commenced within Afar itself. At ˜24 Ma, a new phase of volcanism, principally basaltic dikes but also layered gabbro and granophyre bodies, appeared nearly synchronously throughout the entire Red Sea, from Afar and Yemen to northern Egypt. This second phase of magmatism was accompanied in the Red Sea by strong rift-normal extension and deposition of syn-tectonic sediments, mostly of marine and marginal marine affinity. Sedimentary facies were laterally heterogeneous, being comprised of inter-fingering siliciclastics, evaporite, and carbonate. Throughout the Red Sea, the principal phase of rift shoulder uplift and rapid syn-rift subsidence followed shortly thereafter at ˜20 Ma. Water depths increased dramatically and sedimentation changed to predominantly Globigerina-rich marl and deepwater limestone. Within a few million years of its initiation in the mid-Oligocene the Gulf of Aden continental rift linked the Owen fracture zone (oceanic crust) with the Afar plume. The principal driving force for extension

Metal pollution in Al-Khobar seawater, Arabian Gulf, Saudi Arabia.

Science.gov (United States)

Alharbi, Talal; Alfaifi, Hussain; El-Sorogy, Abdelbaset

2017-06-15

In order to assess heavy metals pollution along the Al-Khobar coastline, 30 seawater samples and 15 sediment ones were collected for Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Hg and Pb analysis by Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). The analysis indicated a southward decreasing pattern in most heavy metal concentrations and the average values of Zn, Fe, Mn, Cu, As and Cr were higher than the ones reported from some worldwide seas and gulfs. Most of the highest levels were recorded within the bays and were related with in situ under sediments especially that composed of clays and very fine sands, and in localities characterized with anthropogenic activities like landfilling, desalination plants, fishing boats, oil spills and solid rubbish. The results of the present study provide useful background for further marine investigation and management in the Arabian Gulf region. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selenium and Mercury Interactions in Apex Predators from the Gulf of Trieste (Northern Adriatic Sea

Directory of Open Access Journals (Sweden)

Jadran Faganeli

2018-02-01

Full Text Available Since the environmental levels of selenium (Se can moderate the bioaccumulation and toxicity of mercury (Hg in marine organisms, their interactions were studied in seawater, sediments, plankton and the benthic (Bull ray Pteromylaeus bovinus, Eagle ray Myliobatis aquila and the pelagic (Pelagic stingray Dasyiatis violacea rays, as apex predators in the Gulf of Trieste (Northern Adriatic Sea. Male and female rays showed no difference in the Se contents in muscle tissue. Pelagic species contained higher Se levels in muscle but slightly lower levels in the livers of both genders. The Hg/Se ratios in seawater dissolved and colloidal fractions, plankton and sediment were <0.5, while those in particulate matter were <1.3. In benthic ray species, a parallel increase in Se and Hg in muscle was observed, so that an increased in Hg (MeHg bioaccumulation results in Se coaccumulation. The Hg/Se ratios (molar in muscle and liver of pelagic and benthic rays were <1.4 and <0.7, respectively. The low levels of Hg in muscle and liver in all the ray species corresponded to low Hg/Se ratios and increases in muscle and liver to 1 at 7 µg/g, dry weight (dw and 5 µg/g dw, respectively, i.e., about 1.6 µg/g wet weight (ww.

A basis for environmental monitoring in the gulf of Batabano applying hydrodynamic simulations

International Nuclear Information System (INIS)

Arriaza Oliveros, L.; Rodas Fernandez, L.; Simanca Cardenas, J.; Milian Lorenz, D.E.; Romero Suarez, P.L.

2006-01-01

The spreading of organic compounds and wastes in seawater depend on the space-time distribution of marine currents. Therefore, for the Environmental Monitoring of sea waters in the Cuban shelf it is necessary to include the marine current variable. A hydrodynamic model is applied in the Gulf of Batabano. The model was validated by using marine currents observed. Any organic compound or wastes in the Batabano or La Broa will moved slowly (1 + - 0.0529 cm/s and 4.7 + - 0.0529 cm/s) until the center and southwestern part of the gulf and the western part of the Isla de la Juventud, affecting for a long time period the SW coast of the gulf. Any pollution in ocean waters adjacent to this shelf will go through the open boundary with a mean velocity between 15 + - 0.25 cm/s and 29.5 + - 0.25 cm/s until the northern part of the Isla de la Juventud; it affects quickly this island and the southwestern and southeastern coasts of the gulf; the pollution will go slowly (1 + - 0.0529 cm/s and 3 + - 0.0529 cm/s) until the central and northeastern part of the gulf

Assessing aquifer storage and recovery feasibility in the Gulf Coastal Plains of Texas

Directory of Open Access Journals (Sweden)

W. Benjamin Smith

2017-12-01

Full Text Available Study region: The Gulf Coast and Carrizo-Wilcox aquifer systems in the Gulf Coastal Plains of Texas. Study focus: Aquifer storage and recovery is a water storage alternative that is underutilized in Texas, a state with both long periods of drought and high intensity storms. Future water storage plans in Texas almost exclusively rely on surface reservoirs, subject to high evaporative losses. This study seeks to identify sites where aquifer storage and recovery (ASR may be successful, especially in recovery of injected waters, by analyzing publicly-available hydrogeologic data. Transmissivity, hydraulic gradient, well density, depth to aquifer, and depth to groundwater are used in a GIS-based index to determine feasibility of implementing an ASR system in the Gulf Coast and Carrizo-Wilcox aquifer systems. New hydrological insights for the region: Large regions of the central and northern Gulf Coast and the central and southern Carrizo-Wilcox aquifer systems are expected to be hydrologically feasible regions for ASR. Corpus Christi, Victoria, San Antonio, Bryan, and College Station are identified as possible cities where ASR would be a useful water storage strategy. Keywords: Aquifer storage and recovery (ASR, GIS, Gulf coast, Carrizo-Wilcox, Managed aquifer recharge (MAR

Hydrodynamic Characteristics and Salinity Patterns in Estero Bay, Lee County, Florida

Science.gov (United States)

Byrne, Michael J.; Gabaldon, Jessica N.

2008-01-01

Estero Bay is an estuary (about 12 miles long and 3 miles wide) on the southwestern Florida coast, with several inlets connecting the bay to the Gulf of Mexico and numerous freshwater tributaries. Continuous stage and salinity data were recorded at eight gaging stations in Estero Bay estuary from October 2001 to September 2005. Continuous water velocity data were recorded at six of these stations for the purpose of measuring discharge. In addition, turbidity data were recorded at four stations, suspended sediment concentration were measured at three stations, and wind measurements were taken at one station. Salinity surveys, within and around Estero Bay, were conducted 15 times from July 2002 to January 2004. The average daily discharge ranged from 35,000 to -34,000 ft3/s (cubic feet per second) at Big Carlos Pass, 10,800 to -11,200 ft3/s at Matanzas Pass, 2,200 to -2,900 ft3/s at Big Hickory Pass, 680 to -700 ft3/s at Mullock Creek, 330 to -370 ft3/s at Estero River, and 190 to -180 ft3/s at Imperial River. Flood tide is expressed as negative discharge and ebb flow as positive discharge. Reduced salinity at Matanzas Pass was negatively correlated (R2 = 0.48) to freshwater discharge from the Caloosahatchee River at Franklin Locks (S-79). Matanzas Pass is hydrologically linked to Hell Peckney Bay; therefore, water-quality problems associated with the Caloosahatchee River also affect Hell Peckney Bay. Rocky Bay was significantly less saline than Coconut Point and Matanzas Pass was significantly less saline than Ostego Bay, based on data from the salinity surveys. The quality-checked and edited continuous data and the salinity maps have been compiled and are stored on the U.S. Geological Survey South Florida Information Access (SOFIA) website (http://sofia.usgs.gov).

A bottom-driven mechanism for distributed faulting in the Gulf of California rift

Science.gov (United States)

Persaud, Patricia; Tan, Eh; Contreras, Juan; Lavier, Luc

2017-11-01

Observations of active faulting in the continent-ocean transition of the Northern Gulf of California show multiple oblique-slip faults distributed in a 200 × 70 km2 area developed some time after a westward relocation of the plate boundary at 2 Ma. In contrast, north and south of this broad pull-apart structure, major transform faults accommodate Pacific-North America plate motion. Here we propose that the mechanism for distributed brittle deformation results from the boundary conditions present in the Northern Gulf, where basal shear is distributed between the Cerro Prieto strike-slip fault (southernmost fault of the San Andreas fault system) and the Ballenas Transform Fault. We hypothesize that in oblique-extensional settings whether deformation is partitioned in a few dip-slip and strike-slip faults, or in numerous oblique-slip faults may depend on (1) bottom-driven, distributed extension and shear deformation of the lower crust or upper mantle, and (2) the rift obliquity. To test this idea, we explore the effects of bottom-driven shear on the deformation of a brittle elastic-plastic layer with the help of pseudo-three dimensional numerical models that include side forces. Strain localization results when the basal shear abruptly increases in a step-function manner while oblique-slip on numerous faults dominates when basal shear is distributed. We further explore how the style of faulting varies with obliquity and demonstrate that the style of delocalized faulting observed in the Northern Gulf of California is reproduced in models with an obliquity of 0.7 and distributed basal shear boundary conditions, consistent with the interpreted obliquity and boundary conditions of the study area.

Trends in Accretion Rates of Riverine Sediments in a Distal Bay and Wetlands Using 7-Beryllium as a Tracer: Fourleague Bay, Louisiana.

Science.gov (United States)

Restreppo, G. A.; Bentley, S. J.; Wang, J.; Xu, K.

2017-12-01

To combat land loss along the Mississippi River Delta, Louisiana has launched a historic campaign to sustain and regrow coastal lands using, in part, sediment diversions. Previous research has focused primarily on sand sized sediment load, which is usually deposited proximal to a river's delta or a diversion's outlet. Fine sediments constitute the majority of sediment load in the Mississippi, but are under-studied with respect to dispersal processes, particularly in terms of sediment supply to distal deltaic bays and wetlands. The Atchafalaya River and associated wetlands serve as prime study areas for this purpose. Bimonthly time-series push cores were collected from May 2015 to May 2016 along ten sites within Fourleague Bay, Louisiana. Fourleague Bay has remained stable against the deteriorative effects of relative sea level rise, standing out along Louisiana's declining coastline. Of the ten field sites, five are located across a longitudinal transect in the middle bay, while the other five are located in adjacent marshes. All sites fall within 10 to 30 km of the Atchafalaya Delta, extending south towards the Gulf of Mexico. Cores were extruded in 2 cm intervals, dried, ground, and analyzed via gamma spectrometry for the presence of 7Be. Inventories of 7Be were then calculated and used to determine daily mass accretion rate (MAR) over twelve months. Average MAR values for the bay and the marshes are compared with Atchafalaya River discharge, wind data, and atmospheric pressure through the year of sampling. Peak marsh MAR, 0.88 ± 0.20 kg m-2 d-1, occurs just after historically high river discharge. Peak bay MAR, 1.2 ± 0.67 kg m-2 d-1, occurs during seasonal low river discharge and calm winds. Average bay and marsh MARs have a moderate to strong, negative correlation when compared. Results indicate sediment bypass of the bay floor during periods of moderate to high river discharge, entering the marshes directly when inundation occurs and enhanced by the passage

The Role of Rift Obliquity in Formation of the Gulf of California

Science.gov (United States)

Bennett, Scott Edmund Kelsey

The Gulf of California illustrates how highly oblique rift geometries, where transform faults are kinematically linked to large-offset normal faults in adjacent pull-apart basins, enhance the ability of continental lithosphere to rupture and, ultimately, hasten the formation of new oceanic basins. The Gulf of California rift has accommodated oblique divergence of the Pacific and North America tectonic plates in northwestern Mexico since Miocene time. Due to its infancy, the rifted margins of the Gulf of California preserve a rare onshore record of early continental break-up processes from which to investigate the role of rift obliquity in strain localization. Using new high-precision paleomagnetic vectors from tectonically stable sites in north-central Baja California, I compile a paleomagnetic transect of Miocene ignimbrites across northern Baja California and Sonora that reveals the timing and distribution of dextral shear associated with inception of this oblique rift. I integrate detailed geologic mapping, basin analysis, and geochronology of pre-rift and syn-rift volcanic units to determine the timing of fault activity on Isla Tiburon, a proximal onshore exposure of the rifted North America margin, adjacent to the axis of the Gulf of California. The onset of strike-slip faulting on Isla Tiburon, ca. 8 - 7 Ma, was synchronous with the onset of transform faulting along a significant length of the nascent plate boundary within the rift. This tectonic transition coincides with a clockwise azimuthal shift in Pacific-North America relative motion that increased rift obliquity. I constrain the earliest marine conditions on southwest Isla Tiburon to ca. 6.4 - 6.0 Ma, coincident with a regional latest Miocene marine incursion in the northern proto-Gulf of California. This event likely flooded a narrow, incipient topographic depression along a ˜650 km-long portion of the latest Miocene plate boundary and corresponds in time and space with formation of a newly

Environmental and economic assessment of discharges from Gulf of Mexico Region Oil and Gas Operations

International Nuclear Information System (INIS)

Gettleson, D.A.

1997-01-01

Task 3 (Environmental Field Sampling and Analysis of NORM, Heavy Metals, and Organics) and 4 (Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas) activities involved continued data analysis and report writing. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gulf of Mexico Region) was issued as a final report during the previous reporting period. Task 6 (Synthesis of Gulf of Mexico Seafood Consumption and Use Patterns) activities included the preparation of the final report. There were no Task 7 (Technology Transfer Plan) activities to report. Task 8 (Project Management and Deliverables) activities involved the submission of the necessary reports and routine management

Scales of seafloor sediment resuspension in the northern Gulf of Mexico

Directory of Open Access Journals (Sweden)

Arne-R. Diercks

2018-04-01

Full Text Available Seafloor sediment resuspension events of different scales and magnitudes and the resulting deep (>1,000 m benthic nepheloid layers were investigated in the northern Gulf of Mexico during Fall 2012 to Summer 2013. Time-series data of size-specific 'in-situ' settling speeds of marine snow in the benthic nepheloid layer (moored flux cameras, particle size distributions (profiling camera, currents (various current meters and stacked time-series flux data (sediment traps were combined to recognize resuspension events ranging from small-scale local, to small-scale far-field to hurricane-scale. One small-scale local resuspension event caused by inertial currents was identified based on local high current speeds (>10 cm s–1 and trap data. Low POC content combined with high lithogenic silica flux at 30 m above bottom (mab compared to the flux at 120 mab, suggested local resuspension reaching 30 mab, but not 120 mab. Another similar event was detected by the changes in particle size distribution and settling speeds of particles in the benthic nepheloid layer. Flux data indicated two other small-scale events, which occurred at some distance, rather than locally. Inertia-driven resuspension of material in shallower areas surrounding the traps presumably transported this material downslope leaving a resuspension signal at 120 mab, but not at 30 mab. The passage of hurricane Isaac left a larger scale resuspension event that lasted a few days and was recorded in both traps. Although hurricanes cause large-scale events readily observable in sediment trap samples, resuspension events small in temporal and spatial scale are not easily recognizable in trapped material as they tend to provide less material and become part of the background signal in the long-term averaged trap samples. We suggest that these small-scale resuspension events, mostly unnoticed in conventional time-series sampling, play an important role in the redistribution and ultimate fate of

Instrument packages to study long-term sediment transport processes in a shallow bay

Science.gov (United States)

Strahle, William J.; Martini, Marinna A.; Davis, Ray E.

1994-01-01

Pressure and near-surface and near-bottom measurements of current, temperature, salinity and light transmission were required in Mobile Bay, a 3 m deep estuary on the Gulf of Mexico. This environment presented several obstacles to obtaining long term observations. Boat traffic, soft estuary bottom, heavy biofouling, rapid sample rates and large data storage were overcome by using instrumentation techniques that are applicable to other estuary systems. Nearly two years of continuous data was collected.

Mobile Bay river plume mixing in the inner shelf

Science.gov (United States)

Parra, S. M.; Book, J. W.; Warner, S. J.; Moum, J.

2017-12-01

The microtidal region (0.5 m spring tides) of the inner shelf outside Mobile Bay presented a complex circulation pattern driven by the pulsed river discharge and winds. Currents, salinity, temperature, and turbulence profiles were measured for up to three weeks in April 2016 at six moorings outside Mobile Bay. Currents varied between locations and with depth. During neap and spring tides the currents were reliably >0.4 and 0.5 m/s) and toward deeper waters, concurrent with the strongest stratification. The possible flow drivers considered include tides, winds, inertial oscillations, waves, and stratification. Turbulent kinetic energy production and dissipation were calculated with multiple methods using data from bottom-mounted, upward-looking acoustic Doppler current profilers sampling at 1 Hz, and using data from line-moored chi-pod turbulent temperature microstructure instruments sampling at 100 Hz. This work explores different forcing mechanisms involved in modulating the circulation and turbulence in a multi-layered pulsed-river inner shelf region in the Gulf of Mexico.

High reproductive synchrony of Acropora (Anthozoa: Scleractinia) in the Gulf of Aqaba, Red Sea

KAUST Repository

Bouwmeester, Jessica

2015-01-05

Coral spawning in the northern Gulf of Aqaba has been reported to be asynchronous, making it almost unique when compared to other regions in the world. Here, we document the reproductive condition of Acropora corals in early June 2014 in Dahab, in the Gulf of Aqaba, 125 km south of previous studies conducted in Eilat, Israel. Seventy-eight percent of Acropora colonies from 14 species had mature eggs, indicating that most colonies will spawn on or around the June full moon, with a very high probability of multi-species synchronous spawning. Given the proximity to Eilat, we predict that a comparable sampling protocol would detect similar levels of reproductive synchrony throughout the Gulf of Aqaba consistent with the hypothesis that high levels of spawning synchrony are a feature of all speciose coral assemblages.

Description and classification of dictyoceratid sponges from the Northern Red Sea

NARCIS (Netherlands)

Helmy, Tamer; Serehy, el Hamed; Mohamed, Saad Zakaria; Soest, van Rob W.M.

2004-01-01

Seven dictyoceratid sponge species were collected from the Gulf of Aqaba, Northern Red Sea. Two new species were recognized: Scalarispongia aqabaensis n. sp. and Spongia lesleighae n. sp. Five others belong to the known species, Fascaplysinopsis reticulata (Hentschel, 1912), Phyllospongia papyracea

Paleoceanographic history of the Guaymas Basin, Gulf of California, during the past 15,000 years based on diatoms, silicoflagellates, and biogenic sediments

Science.gov (United States)

Barron, J.A.; Bukry, D.; Dean, W.E.

2005-01-01

High-resolution records of calcium carbonate, biogenic opal, diatoms, and silicoflagellates from western Guaymas Basin gravity core GGC55 and piston core JPC56 and eastern Guaymas Basin DSDP Site 480 reveal a complex paleoceanographic history of the central Gulf of California during the past 15,000 years. Prior to ??? 6.2 ka, the eastern and western Guaymas Basin proxy records were remarkably similar. After conditions similar to those of today during the B??lling-Allerod, the Younger Dryas (YD) saw a major drop in diatom production, coincident with increased calcium carbonate and tropical microfossils suggestive of El Nin??o-like conditions. Biosiliceous productivity began increasing during the latter part of the YD, but it was only during the earliest Holocene (11.6 to 11.0 ka) that conditions similar to those of the B??lling-Allerod returned to the central Gulf. Between around 11.0 and 6.2 ka, tropical diatoms and silicoflagellates were virtually absent from the central Gulf, as relatively cooler and fresher surface waters resembling those of the modern northern Gulf were present in the central Gulf. Beginning at about 6.2 ka, tropical diatoms and silicoflagellates began increasing in the central Gulf, and coccoliths returned to western Gulf sediments. The onset of modern-day monsoon conditions in the American Southwest required the presence of warm SSTs in the northern Gulf, which probably did not occur until after about 5.4 ka, when tropical diatoms and silicoflagellates became relatively common in the central Gulf. Modern east-west contrasts, which arise from late winter-early spring coastal upwelling on the mainland side and lower diatom productivity on the western side of the Gulf, commenced between 6.2 and 5.4 ka, possibly due to a shift in the direction of late winter-early spring winds more towards the southeast, or down the axis of the Gulf. This proposed wind shift might have ultimately been due to a late Holocene strengthening of ENSO-like conditions

Monitoring changing geologic features along the Texas Gulf Coast

Science.gov (United States)

Hunter, R. E. (Principal Investigator)

1972-01-01

The author has identified the following significant results. Water truth observations, NASA aerial photography from an altitude of 60,000 feet, and ERTS-1 imagery made off the South Texas coast showed a mutually consistent pattern of water turbidity in the Gulf of Mexico. At the time of the measurements, plumes of turbid water were being formed by ebb-tidal discharges from the bays through tidal passes and were being diverted southward by the coastwise drift. The occurrence of the bands of turbid and relatively clear water suggests the existence of large scale helical circulation cells having axes almost parallel to shore with the outer turbid band probably being a zone of surface divergence and bottom water upwelling. The impingement of a turbid water mass onto the shoreline suggests that some, and perhaps most, of the suspended sediment in nearshore waters may not have been stirred up from the nearshore sea floor but may have traveled long distances in the water mass, perhaps even having remained in suspension from the time of its entry into the Gulf tidal inlets such as Aransas Pass.

Preliminary observations of environmental damage due to the Gulf War

International Nuclear Information System (INIS)

El-Baz, F.

1992-01-01

Preparing for and conducting the Gulf War resulted in much damage to the environment of the region. The first and most visible effect is related to the damage caused by oil well fires in terms of air pollution as well as the potential damage to the petroleum reservoirs. The second detrimental effect has been caused by the oil spill in the Gulf water. Hundreds of miles of the western coastline of the Gulf are already covered with oil. Petroleum 'mats' have settled on coral reefs and have reduced Gulf water productivity. Foremost among the irreparable damages are changes to the terrain due to the digging of trenches, building walls of soil and otherwise disturbing the desert pavement in and around Kuwait. Disruption of the, usually, one-grain thick layer of pebbles on the desert floor exposes soil to wind action. Changing the contours of the normally flat land increases resistance to the wind and increases the potential of particle transport until the land is peneplained. This condition will increase the frequency and the ferocity of dust storms in the region. It will also result in the formation of new sand dunes; sand drifts already exist along roads in northern Kuwait. It is believed that the detrimental effects on the atmosphere will last for years, on the Gulf water for decades, and on the desert surface for centuries. (author). 12 refs, 1 fig

Preliminary observations of environmental damage due to the Gulf War

Energy Technology Data Exchange (ETDEWEB)

El-Baz, F [Boston Univ., Boston, MA (United States). Center for Remote Sensing

1992-02-01

Preparing for and conducting the Gulf War resulted in much damage to the environment of the region. The first and most visible effect is related to the damage caused by oil well fires in terms of air pollution as well as the potential damage to the petroleum reservoirs. The second detrimental effect has been caused by the oil spill in the Gulf water. Hundreds of miles of the western coastline of the Gulf are already covered with oil. Petroleum 'mats' have settled on coral reefs and have reduced Gulf water productivity. Foremost among the irreparable damages are changes to the terrain due to the digging of trenches, building walls of soil and otherwise disturbing the desert pavement in and around Kuwait. Disruption of the, usually, one-grain thick layer of pebbles on the desert floor exposes soil to wind action. Changing the contours of the normally flat land increases resistance to the wind and increases the potential of particle transport until the land is peneplained. This condition will increase the frequency and the ferocity of dust storms in the region. It will also result in the formation of new sand dunes; sand drifts already exist along roads in northern Kuwait. It is believed that the detrimental effects on the atmosphere will last for years, on the Gulf water for decades, and on the desert surface for centuries. (author). 12 refs, 1 fig.

Over 100 years of environmental change recorded by foraminifers and sediments in Mobile Bay, Alabama, Gulf of Mexico, USA

Science.gov (United States)

Osterman, Lisa E.; Smith, Christopher G.

2012-12-01

The marine microfauna of Mobile Bay has been profoundly influenced by the development and expansion of the primary shipping channel over the last ˜100 years. Foraminifers and sediments from seven box cores with excess lead-210 chronology document that channel dredging and spoil disposal have altered circulation, reduced estuarine mixing, changed sedimentation patterns, and caused a faunal turnover within the bay. Beginning in the late 1800s, changes in estuarine mixing allowed for greater low-pH freshwater influence in the bay, and ultimately began environmental changes that resulted in the loss of calcareous foraminifers. By the early 1900s, box cores throughout Mobile Bay record a ˜100-year trend of increasing calcareous test dissolution that continues to the present. Since the completion of the current shipping channel in the 1950s, restricted tidal flushing and increased terrestrial organic matter, documented by carbon-to-nitrogen ratios, stimulated an increase in agglutinated foraminiferal densities. However, in deeper areas of the bay, hypoxic water has negatively impacted the marine microfauna. Comparisons of the present-day foraminiferal assemblage with foraminifers collected in the early 1970s indicate that the continued biologic loss of calcareous foraminifers in the bay has allowed the introduction of a new agglutinated foraminiferal species into the bay.

Impacts of Suspended Sediment and Estuarine - Shelf Exchange Pathways on Shelf Ecosystem Dynamics in the Northern Gulf of Mexico

Science.gov (United States)

Wiggert, J. D.; Pan, C.; Dinniman, M. S.; Lau, Y.; Fitzpatrick, P. J.; O'Brien, S. J.; Bouchard, C.; Quas, L. M.; Miles, T. N.; Cambazoglu, M. K.; Dykstra, S. L.; Dzwonkowski, B.; Jacobs, G. A.; Church, I.; Hofmann, E. E.

2017-12-01

A circulation model based on the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System, with coupled biogeochemical and sediment transport modules, has been implemented for Mississippi Sound and the adjacent continental shelf region. The model has 400-m horizontal resolution, 24 vertical layers, and includes wetting/drying capability to resolve shallow inshore regions. The circulation model was spun-up using oceanographic initial and lateral boundary conditions provided by a 1-km resolution regional implementation of the Navy Coastal Ocean Model (NCOM) in the Gulf of Mexico. The biogeochemical module includes multiple size classes of phytoplankton, zooplankton and detritus, a fish larvae compartment, and explicitly tracks dissolved oxygen with benthic cycling interaction. The sediment transport model is implemented based on benthic mapping data that provides bottom sediment type distributions and spatio-temporal validation. A regionally specific atmospheric forcing product that provides improved spatial and temporal resolution, including diurnal sea breeze impacts, has been developed and applied. Model experiments focus on periods when comprehensive ship-based sampling was deployed by the CONCORDE (Consortium for Coastal River-Dominated Ecosystems) research program, which was established to investigate the complex fine-scale biological, chemical and physical interactions in a marine system controlled by pulsed-river plume dynamics. Biophysical interactions and biogeochemical variability associated with estuarine - shelf exchanges between nearshore lagoonal estuarine waters and the continental shelf revealed by the model provide new insight into how seasonal variation of hydrological forcing conditions influence ecological and biogeochemical processes in the highly productive Northern Gulf region. Application of the COAWST-based model system with and without inclusion of the sediment transport module demonstrates how suspended sediment in the

Influence of orographically steered winds on Mutsu Bay surface currents

Science.gov (United States)

Yamaguchi, Satoshi; Kawamura, Hiroshi

2005-09-01

Effects of spatially dependent sea surface wind field on currents in Mutsu Bay, which is located at the northern end of Japanese Honshu Island, are investigated using winds derived from synthetic aperture radar (SAR) images and a numerical model. A characteristic wind pattern over the bay was evidenced from analysis of 118 SAR images and coincided with in situ observations. Wind is topographically steered with easterly winds entering the bay through the terrestrial gap and stronger wind blowing over the central water toward its mouth. Nearshore winds are weaker due to terrestrial blockages. Using the Princeton Ocean Model, we investigated currents forced by the observed spatially dependent wind field. The predicted current pattern agrees well with available observations. For a uniform wind field of equal magnitude and average direction, the circulation pattern departs from observations demonstrating that vorticity input due to spatially dependent wind stress is essential in generation of the wind-driven current in Mutsu Bay.

Seagrass distribution and abundance in Eastern Gulf of Mexico coastal waters

Science.gov (United States)

Iverson, Richard L.; Bittaker, Henry F.

1986-05-01

The marine angiosperms Thalassia testudinum, Syringodium filiforme, and Halodule wrightii form two of the largest reported seagrass beds along the northwest and southern coasts of Florida where they cover about 3000 square km in the Big Bend area and about 5500 square km in Florida Bay, respectively. Most of the leaf biomass in the Big Bend area and outer Florida Bay was composed of Thalassia testudinum and Syringodium filiforme which were distributed throughout the beds but which were more abundant in shallow depths. A short-leaved form of Halodule wrightii grew in monotypic stands in shallow water near the inner edges of the beds, while Halophila decipiens and a longer-leaved variety of H. wrightii grew scattered throughout the beds, in monotypic stands near the outer edges of the beds, and in deeper water outside the beds. Halophila engelmanni was observed scattered at various depths throughout the seagrass beds and in monospecific patches in deep water outside the northern bed. Ruppia maritima grew primarily in brackish water around river mouths. The cross-shelf limits of the two major seagrass beds are controlled nearshore by increased water turbidity and lower salinity around river mouths and off-shore by light penetration to depths which receive 10% or more of sea surface photosynthetically active radiation. Seagrasses form large beds only along low energy reaches of the coast. The Florida Bay seagrass bed contained about twice the short-shoot density of both Thalassia testudinum and Syringodium filiforme, for data averaged over all depths, and about four times the average short-shoot density of both species in shallow water compared with the Big Bend seagrass bed. The differences in average seagrass abundance between Florida Bay and the Big Bend area may be a consequence of the effects of greater seasonal solar radiation and water temperature fluctuations experienced by plants in the northern bed, which lies at the northern distribution limit for American

Distribution of calanoid copepods in the Arabian sea and Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Stephen, R.

The distribution of calanoid copepods from the northern Arabian Sea and Bay of Bengal is discussed in relation to thermocline. The inshore offshore zonation of a neritic, shelf an oceanic communities was traced based on the species composition...

Marine magnetic studies in the northern Bay of Bengal, preliminary results

Digital Repository Service at National Institute of Oceanography (India)

Ramana, M.V.; Subrahmanyam, V.; Krishna, K.S.; Chaubey, A.K.; Sarma, K.V.L.N.S.; Murty, G.P.S.; Murty, P.S.N.; Rao, D.G.; Mittal, G.S.; Drolia, R.K.

The bathymetric and total magnetic intensity data collected along six E-W tracks were analysed and presented as stacked anomaly profiles. A first order basement configuration model was generated across the Bay of Bengal. The model studies indicate...

Concentration of Antifouling Biocides and Metals in Sediment Core Samples in the Northern Part of Hiroshima Bay

Directory of Open Access Journals (Sweden)

Noritaka Tsunemasa

2014-06-01

Full Text Available Accumulation of Ot alternative antifoulants in sediment is the focus of this research. Much research had been done on surface sediment, but in this report, the accumulation in the sediment core was studied. The Ot alternative antifoulants, Diuron, Sea-Nine211, and Irgarol 1051, and the latter’s degradation product, M1, were investigated in five samples from the northern part of Hiroshima Bay. Ot compounds (tributyltin (TBT and triphenyltin (TPT were also investigated for comparison. In addition, metal (Pb, Cu, Zn, Fe and Mn levels and chronology were measured to better understand what happens after accumulation on the sea floor. It was discovered that Ot alternative antifoulant accumulation characteristics in sediment were like Ot compounds, with the concentration in the sediment core being much higher than surface sediment. The concentration in sediment seems to have been affected by the regulation of Ot compounds in 1990, due to the concentration of Ot alternative antifoulants and Ot compounds at the survey point in front of the dock, showing an increase from almost the same layer after the regulation.

Radium variability produced by shelf-water transport and mixing in the western Gulf of Mexico

International Nuclear Information System (INIS)

Reid, D.F.

1984-01-01

226 Ra and 228 Ra exhibit significant temporal and spatial variability in the near-surface western Gulf of Mexico. Concentrations of both isotopes during March 1976 were approx. 22 to 26% greater than those observed during February 1973. It is shown that analytical differences cannot account for this increase. Consideration of radium levels in the western Caribbean Sea indicates that there must be an internal source of radium that has a significant but temporally variable influence on near-surface radium concentrations in the western Gulf. Comparisons of radium, salinity, and temperature data from 1973 and 1976 provide evidence that advective transport and mixing of radium-rich shelf water with the interior water column of the western basin is responsible for the variability. By plotting 228 Ra vs 226 Ra from this region, estimates of the apparent shelf-water component in the upper water column can be made. The results indicate 36% over the northern slope, 10 to 18% in the central western Gulf, and 3 to 7% over Campeche Bank. In addition to explaining observed short-term variations of radium in this region, this information should be useful for environmental impact assessments concerned with industrial discharges on the northern shelf. (author)

Observing storm surges in the Bay of Bengal from satellite altimetry

Digital Repository Service at National Institute of Oceanography (India)

Antony, C.; Testut, L.; Unnikrishnan, A.S.

with the large tidal ranges give rise to extreme sea level in the head bay and surrounding regions. Moreover, low-lying nature of the coast and the dense population in the region make the coasts of the northern Bay of Bengal highly vulnerable to storm surges...-gauge data during the passage of the hurricane Igor that crossed Newfoundland in 2010. For this event, St. John’s tide gauge recorded a maximum surge of 94 cm and Jason-2 (the track located 89 km away from the tide-gauge station) showed positive sea-level...

Baltic Sea ice and environmental and societal implications from the comparative analysis of the Bay of Bothnia and the Gulf of Riga

Directory of Open Access Journals (Sweden)

Élise Lépy

2012-12-01

Full Text Available This article contributes to many studies on sea ice often carried out by geophysicists and rarely by geographers. Thus, it aims to understand climatic and marine processes of ice formation and break-up of littoral waters and coastal sea, and their environmental, economic and societal consequences in the Baltic Sea. The interest of this research lies in the comparative analysis of two regions: the Bay of Bothnia and the Gulf of Riga. These two case studies are politically, economically and culturally different and help to understand the diversity of reactions and adaptations to the human management of the natural constraint imposed by sea ice phenomena. By using a systemic approach, quite common when studying geographical issues of nature and societies, the work has contributed to a better knowledge of the natural environment of Baltic Sea ice showing a significant interannual variability and a spatial internal diversity of sea ice conditions in the Baltic Sea. It also raises the questions of the environmental determinism which is rejected by the remarkable adaptability of coastal population. Finally, the socio-economic implications of historical changes of sea ice features are emphasized showing that future Baltic Sea ice conditions should be carefully considered when talking about global evolution.

Seasonal phytoplankton blooms in the Gulf of Aden revealed by remote sensing

KAUST Repository

Gittings, John

2016-11-25

The Gulf of Aden, situated in the northwest Arabian Sea and linked to the Red Sea, is a relatively unexplored ecosystem. Understanding of large-scale biological dynamics is limited by the lack of adequate datasets. In this study, we analyse 15 years of remotely-sensed chlorophyll-a data (Chl-a, an index of phytoplankton biomass) acquired from the Ocean Colour Climate Change Initiative (OC-CCI) of the European Space Agency (ESA). The improved spatial coverage of OC-CCI data in the Gulf of Aden allows, for the first time, an investigation into the full seasonal succession of phytoplankton biomass. Analysis of indices of phytoplankton phenology (bloom timing) reveals distinct phytoplankton growth periods in different parts of the gulf: a large peak during August (mid-summer) in the western part of the gulf, and a smaller peak during November (mid-autumn) in the lower central gulf and along the southern coastline. The summer bloom develops rapidly at the beginning of July, and its peak is approximately three times higher than that of the autumnal bloom. Remotely-sensed sea-surface temperature (SST), wind-stress curl, vertical nutrient profiles and geostrophic currents inferred from the sea-level anomaly, were analysed to examine the underlying physical mechanisms that control phytoplankton growth. During summer, the prevailing southwesterlies cause upwelling along the northern coastline of the gulf (Yemen), leading to an increase in nutrient availability and enhancing phytoplankton growth along the coastline and in the western part of the gulf. In contrast, in the central region of the gulf, lowest concentrations of Chl-a are observed during summer, due to strong downwelling caused by a mesoscale anticyclonic eddy. During autumn, the prevailing northeasterlies enable upwelling along the southern coastline (Somalia) causing local nutrient enrichment in the euphotic zone, leading to higher levels of phytoplankton biomass along the coastline and in the lower central gulf

Stratigraphy and structural development of the southwest Isla Tiburón marine basin: Implications for latest Miocene tectonic opening and flooding of the northern Gulf of California

Science.gov (United States)

Bennett, Scott E. K.; Oskin, Michael; Dorsey, Rebecca; Iriondo, Alexander; Kunk, Michael J.

2015-01-01

foraminifera from this section. Results from biostratigraphy and geochronology thus constrain earliest marine deposition on SWIT to ca. 6.2 ± 0.2 Ma, coincident with a regional-scale latest Miocene marine incursion into the northern proto-Gulf of California. This regional marine incursion flooded the northernmost, >500-km-long portion of the Gulf of California shear zone, a narrow belt of localized strike-slip faulting, clockwise block rotation, and subsiding pull-apart basins. Oblique Pacific-North America relative plate motion gradually localized in the >1000-km-long Gulf of California shear zone ca. 9-6 Ma, subsequently permitting the punctuated south to north flooding of the incipient Gulf of California seaway.

Contribution of chronic petroleum inputs to Narragansett Bay and Rhode Island Sound sediments

Energy Technology Data Exchange (ETDEWEB)

Van Vleet, E S; Quin, J G

1978-05-01

Sediment cores from Narragansett Bay and Rhode Island Sound have been analyzed for petroleum hydrocarbons and compared with a relatively unpolluted sediment core from the Gulf of Maine. The sediments were analyzed for unbound hydrocarbons, hydrocarbons bound or closely associated with humic substances, and residual hydrocarbons bound or closely associated with the clay mineral or kerogen matrix. Results indicated that in general 90-100% of the hydrocarbons were in the unbound form and could be easily extracted with organic solvents. The petroleum hydrocarbons decreased with depth at all stations. Biogenic hydrocarbons (nC/sub 25/, nC/sub 27/, nC/sub 29/, and nC/sub 31/) made up an increasingly greater percentage of the total with increasing depth. The hydrocarbons in the Narragansett Bay sediments and near surface Rhode Island Sound sediments strongly resembled the hydrocarbons previously reported for the Providence River and upper Narragansett Bay. These petroleum-like hydrocarbons were shown to be largely introduced to the river and bay through chronic inputs from a municipal wastewater treatment plant. These hydrocarbons then undergo sedimentation throughout the entire bay and into Rhode Island Sound. Preliminary calculations indicate that over 0.2 million t (tonne) of petroleum hydrocarbons may be transported to the marine environment annually from municipal treatment plants. Most of these hydrocarbons appear to accumulate in estuarine and coastal sediments.

EX1202L3 :Gulf of Mexico Exploration on NOAA Ship Okeanos Explorer between 20120411 and 20120429

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — During EX1202 Leg III between April 11 and April 29, 2012 on NOAA Ship Okeanos Explorer (EX), 24-hour operations occured in targeted areas in the Northern Gulf of...

Structural and Tectonic Map Along the Pacific-North America Plate Boundary in Northern Gulf of California, Sonora Desert and Valle de Mexicali, Mexico, from Seismic Reflection Evidence

Science.gov (United States)

Gonzalez-Escobar, M.; Suarez-Vidal, F.; Mendoza-Borunda, R.; Martin Barajas, A.; Pacheco-Romero, M.; Arregui-Estrada, S.; Gallardo-Mata, C.; Sanchez-Garcia, C.; Chanes-Martinez, J.

2012-12-01

Between 1978 and 1983, Petróleos Mexicanos (PEMEX) carried on an intense exploration program in the northern Gulf of California, the Sonora Desert and the southern part of the Mexicali Valley. This program was supported by a seismic reflection field operation. The collected seismic data was 2D, with travel time of 6 s recording, in 48 channels, and the source energy was: dynamite, vibroseis and air guns. Since 2007 to present time, the existing seismic data has been re-processing and ire-interpreting as part of a collaboration project between the PEMEX's Subdirección de Exploración (PEMEX) and CICESE. The study area is located along a large portion of the Pacific-North America plate boundary in the northern Gulf of California and the Southern part of the Salton Trough tectonic province (Mexicali Valley). We present the result of the processes reflection seismic lines. Many of the previous reported known faults were identify along with the first time described located within the study region. We identified regions with different degree of tectonic activity. In structural map it can see the location of many of these known active faults and their associated seismic activity, as well as other structures with no associated seismicity. Where some faults are mist placed they were deleted or relocated based on new information. We included historical seismicity for the region. We present six reflection lines that cross the aftershocks zone of the El Mayor-Cucapah earthquake of April 4, 2010 (Mw7.2). The epicenter of this earthquake and most of the aftershocks are located in a region where pervious to this earthquake no major earthquakes are been reported. A major result of this study is to demonstrate that there are many buried faults that increase the seismic hazard.

Changes in Microbial Plankton Assemblages Induced by Mesoscale Oceanographic Features in the Northern Gulf of Mexico.

Directory of Open Access Journals (Sweden)

Alicia K Williams

Full Text Available Mesoscale circulation generated by the Loop Current in the Northern Gulf of Mexico (NGOM delivers growth-limiting nutrients to the microbial plankton of the euphotic zone. Consequences of physicochemically driven community shifts on higher order consumers and subsequent impacts on the biological carbon pump remain poorly understood. This study evaluates microbial plankton <10 μm abundance and community structure across both cyclonic and anti-cyclonic circulation features in the NGOM using flow cytometry (SYBR Green I and autofluorescence parameters. Non-parametric multivariate hierarchical cluster analyses indicated that significant spatial variability in community structure exists such that stations that clustered together were defined as having a specific 'microbial signature' (i.e. statistically homogeneous community structure profiles based on relative abundance of microbial groups. Salinity and a combination of sea surface height anomaly and sea surface temperature were determined by distance based linear modeling to be abiotic predictor variables significantly correlated to changes in microbial signatures. Correlations between increased microbial abundance and availability of nitrogen suggest nitrogen-limitation of microbial plankton in this open ocean area. Regions of combined coastal water entrainment and mesoscale convergence corresponded to increased heterotrophic prokaryote abundance relative to autotrophic plankton. The results provide an initial assessment of how mesoscale circulation potentially influences microbial plankton abundance and community structure in the NGOM.

Phosphorus Fluxes from Three Coastal Watersheds under Varied Agriculture Intensities to the Northern Gulf of Mexico

Directory of Open Access Journals (Sweden)

Songjie He

2018-06-01

Full Text Available This study aims to evaluate recent total phosphorus (TP and dissolved inorganic phosphorus (DIP transport from three coastal rivers—the Calcasieu, Mermentau, and Vermilion Rivers—that drain watersheds with varied agriculture intensities (21%, 67%, and 61%, respectively into the northern Gulf of Mexico, one of the world’s largest summer hypoxic zones. The study also examined the spatial trends of TP and DIP from freshwater to saltwater along an 88-km estuarine reach with salinity increasing from 0.02 to 29.50. The results showed that from 1990–2009 to 2010–2017, the TP fluxes for one of the agriculture-intensive rivers increased while no significant change was found for the other two rivers. Change in river discharge was the main reason for this TP flux trend. The two more agriculture-intensive river basins showed consistently higher TP and DIP concentrations and fluxes, as well as higher DIP:TP ratios than the river draining less agriculture-intensive land, confirming the strong effect of land uses on phosphorus input and speciation. Longitudinal profiles of DIP along the salinity gradient of the estuarine reach displayed characteristic input behavior. Desorption of DIP from suspended solids and river bed sediments, urban inputs, as well as stronger calcium carbonate and phosphorus co-precipitation at the marine endmember could be the reasons for such mixing dynamics.

Centennial-scale links between Atlantic Ocean dynamics and hydroclimate over the last 4400 years: Insights from the northern Gulf of Mexico

Science.gov (United States)

Thirumalai, K.; Quinn, T. M.; Okumura, Y.; Richey, J. N.; Partin, J. W.; Poore, R. Z.

2015-12-01

Surface circulation in the Atlantic Ocean is an important mediator of global climate and yet its variability is poorly constrained on centennial timescales. Changes in the Atlantic meridional overturning circulation (AMOC) have been implicated in late Holocene climate variability in the Western Hemisphere, although the relationship between AMOC variability and hydroclimate is uncertain due to the lack of sufficiently highly resolved proxy records. Here we present a replicated reconstruction of sea-surface temperature (SST) and salinity (SSS) from the Garrison Basin in the northern Gulf of Mexico (NGOM) spanning the last 4,400 years to better constrain past sea-surface conditions. We generated time series of paired Mg/Ca (SST proxy) and δ18O (SST and SSS proxy) variations in planktic foraminifer Globigerinoides ruber (white variety) from three multi-cores collected in 2010. Using a Monte Carlo-based technique we produce a stacked record from the three multi-cores and constrain analytical, calibration, chronological, and sampling uncertainties. We apply this technique to existing paired Mg/Ca- δ18O studies in the Gulf of Mexico and Atlantic Ocean to facilitate comparison between time-uncertain proxy reconstructions. The Garrison Basin stack exhibits large centennial-scale variability (σSST~0.6°C; δ18Osw~0.17‰) and indicates a substantially cool (0.9±0.5°C) and fresh (0.26±0.1‰) Little Ice Age (LIA; 1450-1850 A.D.), corroborating extant records from the Gulf of Mexico. Focusing on the last millennium, we analyze a suite of oceanic and terrestrial proxy records to demonstrate a centennial-scale link between salt advection in the Atlantic Ocean, a diagnostic parameter of ocean circulation, and hydroclimate in the adjacent continents. The ensuing multiproxy relationships seem to be consistent with spatial field correlations of limited salinity and rainfall instrumental/reanalysis data, which suggest that NGOM salinity varies with large-scale Atlantic Ocean

Nutrient and physical profile data from four Microbial Exchanges and Coupling in Coastal Atlantic Systems (MECCAS) cruises collected aboard the R/V Gyre at the mouth of the Chesapeake Bay and northern Atlantic Ocean from February 17, 1985 to September 7, 1986 (NODC Accession 8800324)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Microbial Exchanges and Coupling in Coastal Atlantic Systems (MECCAS) cruise data collected aboard the R/V Gyre at the mouth of the Chesapeake Bay and northern...

Hurricane Ike Deposits on the Bolivar Peninsula, Galveston Bay, Texas

Science.gov (United States)

Evans, Cynthia A.; Wilkinson, M. J.; Eppler, Dean

2011-01-01

In September 2008, Hurricane Ike made landfall on Galveston Bay, close to the NASA Johnson Space Center (JSC). The storm flooded much of the area with a storm surge ranging from 11 -20 feet. The Bolivar peninsula, the southeastern coast of Galveston Bay, experienced the brunt of the surge. Several agencies collected excellent imagery baselines before the storm and complementary data a few days afterward that helped define the impacts of the storm. In April of 2011, a team of scientists and astronauts from JSC conducted field mapping exercises along the Bolivar Peninsula, the section of the Galveston Bay coast most impacted by the storm. Astronauts routinely observe and document coastal changes from orbit aboard the International Space Station. As part of their basic Earth Science training, scientists at the Johnson Space Center take astronauts out for field mapping exercises so that they can better recognize and understand features and processes that they will later observe from the International Space Station. Using pre -storm baseline images of the Bolivar Peninsula near Rollover Pass and Gilchrist (NOAA/Google Earth Imagery and USGS aerial imagery and lidar data), the astronauts mapped current coastline positions at defined locations, and related their findings to specific coastal characteristics, including channel, jetties, and other developments. In addition to mapping, we dug trenches along both the Gulf of Mexico coast as well as the Galveston Bay coast of the Bolivar peninsula to determine the depth of the scouring from the storm on the Gulf side, and the amount of deposition of the storm surge deposits on the Bay side of the peninsula. The storm signature was easy to identify by sharp sediment transitions and, in the case of storm deposits, a layer of storm debris (roof shingles, PVC pipes, etc) and black, organic rich layers containing buried sea grasses in areas that were marshes before the storm. The amount of deposition was generally about 20 -25 cm

Anomalous Ba/Ca signals associated with low temperature stresses in Porites corals from Daya Bay, northern South China Sea

Institute of Scientific and Technical Information of China (English)

Tianran Chen; Kefu Yu; Shu Li; Tegu Chen; Qi Shi

2011-01-01

Barium to calcium (Ba/Ca) ratio in corals has been considered as a useful geochemical proxy for upwelling,river flood and other oceanic processes.However,recent studies indicated that additional environmental or biological factors can influence the incorporation of Ba into coral skeletons.In this study,Ba/Ca ratios of two Porites corals collected from Daya Bay,northern South China Sea were analyzed.Ba/Ca signals in the two corals were 'anomalous' in comparison with Ba behaviors seen in other near-shore corals influenced by upwelling or riverine runoff.Our Ba/Ca profiles displayed similar and remarkable patterns characterized by low and randomly fluctuating background signals periodically interrupted by sharp and large synchronous peaks,clearly indicating an environmental forcing.Further analysis indicated that the Ba/Ca profiles were not correlated with previously claimed environmental factors such as precipitation,coastal upwelling,anthropogenic activities or phytoplankton blooms in other areas.The maxima of Ba/Ca appeared to occur in the period of Sr/Ca maxima,coinciding with the winter minimum temperatures,which suggests that the anomalous high Ba/Ca signals were related to winter-time low sea surface temperature.We speculated that the Ba/Ca peaks in corals of the Daya Bay were most likely the results of enrichment of Ba-rich particles in their skeletons when coral polyps retracted under the stresses of anomalous winter low temperatures.In this case,Ba/Ca ratio in relatively high-latitude corals can be a potential proxy for tracing the low temperature stress.

STS-45 Earth observation of the Persian Gulf and the island of Abu Ali

Science.gov (United States)

1992-01-01

STS-45 Earth observation taken aboard Atlantis, Orbiter Vehicle (OV) 104, is of the northern reaches of the Persian Gulf with the sunglint pattern centered on the Saudi Arabian island of Abu Ali. Bright features along the coast are thought to be deposits of oil, released from a terminal offshore of Kuwait during the recent Persian Gulf War. Further up the coast, in Kuwait, the black, oil-soaked desert surrounding the site of the oil well fires is clearly visible. View was taken from an altitude of 160 nautical miles with OV-104 located at 28 degrees north and 52.8 degrees east. During the STS-45 mission, an international survey team focused on oil contamination of the shallow-water habitants in the area north of Abu Ali Island. Crewmembers contacted the NOAA survey vessel, the R/V Mt. Mitchell, several times and photographed water color and sunglint within the study area and throughout the entire Persian Gulf. These photographic data are expected to aid the Persian Gulf researchers in

Natural and Anthropogenic Causes of Accelerated Sediment Accumulation Rates in Nehalem Bay Salt Marshes, Oregon

Science.gov (United States)

Molino, G. D.; Wheatcroft, R. A.; Peck, E. K.; Brophy, L.

2016-12-01

Vertical sediment accretion in estuarine salt marshes occurs as sediments settle out of the water column and onto marsh soils during periods of tidal inundation - thus accretion is influenced by both relative sea level rise (RSLR) and sediment flux to the estuary. Oregon estuaries are understudied compared to their East and Gulf Coast counterparts, but provide a unique opportunity to disentangle these effects. A broader study in three Oregon estuaries (Peck et al., this session) indicates RSLR as the dominant factor controlling sedimentation rates. Working in Nehalem Bay (northern Oregon coast), replicate sediment cores were taken along several transects across an elevation gradient for analysis of sediment and carbon accumulation using CT scans, gamma detection of Pb-210, X-Ray Fluorescence (XRF) and Loss-on-Ignition (LOI). Preliminary results indicate sediment accumulation rates over the past century are higher than rates seen in other comparable Oregon salt marshes; this is consistent with past studies and preliminary analysis of remote sensing data that show significant horizontal expansion of Nehalem marshes. A number of possible causes for the high sediment accumulation rates - hydroclimate of Nehalem River, extensive timber harvesting, forest fires such as the so-called Tillamook Burns, and diking of adjacent marshes - are being explored.

Particle fluxes in the Bay of Bengal measurEd. by sediment traps

Digital Repository Service at National Institute of Oceanography (India)

Ramaswamy, V.; Parthiban, G.

Particle fluxes were measured between October, 1987 and March, 1988 using six automated time series sediment traps at three locations in the northern, central and southern Bay of Bengal. Particle fluxes varied between 16.8 and 345 mg m/2 day/1...

Distribution of moon jellyfish Aurelia aurita in relation to summer hypoxia in Hiroshima Bay, Seto Inland Sea

Science.gov (United States)

Shoji, Jun; Kudoh, Takaya; Takatsuji, Hideyuki; Kawaguchi, Osamu; Kasai, Akihide

2010-02-01

Biological and physical surveys were conducted in order to investigate the relationship between environmental conditions and the distribution of moon jellyfish Aurelia aurita in Hiroshima Bay, western Seto Inland Sea, Japan. Moon jellyfish and ichthyoplankton were collected at 13 stations in Hiroshima Bay during monthly surveys from July to September in 2006 and 2007. Surface temperature in 2006 was significantly lower during the August and September cruises and surface salinity was lower during all cruises than in 2007. Moon jellyfish was the most dominant gelatinous plankton collected, accounting for 89.7% in wet weight. Mean moon jellyfish abundance in 2006 was higher than that in 2007 from July through September, with significant inter-year differences for July and September. Variability in precipitation and nutritional input from the Ohta River, northernmost part of Hiroshima Bay, were suggested as possible factors affecting the inter-annual variability in moon jellyfish abundance in the coastal areas of northern Hiroshima Bay. Moon jellyfish were more abundant in the coastal areas of northern Hiroshima Bay, where the dissolved oxygen (DO) concentration was lower, while low in the central part of the bay. Japanese anchovy Engraulis japonicus eggs were most dominant (58.1% in number) among the ichthyoplankton and were abundant in the central area of Hiroshima Bay. Explanatory analysis was conducted to detect possible effects of environmental conditions on the abundance of moon jellyfish and Japanese anchovy eggs during the summer months in Hiroshima Bay. Of the environmental conditions tested (temperature, salinity and DO of surface and bottom layers at each sampling station), bottom DO had the most significant effect on the moon jellyfish abundance: there was a negative correlation between the bottom DO and the moon jellyfish abundance in Hiroshima Bay during summer.

Zooplankton standing stock, community structure and diversity in the northern Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Goswami, S.C.; Srivastava, Y.

The effects of large scale oil spill, which occurred during the Gulf War in 1991 on zooplankton standing stock, community structure and diversity in the northern Arabian Sea were studied. Surface (1-0 m) and vertical zooplankton hauls (200-0 m, 250...

Chasing Sources and Transports of Methane Plumes in the Northern Gulf of Mexico Using In Situ Sensors on Untethered Landers

Science.gov (United States)

Martens, C. S.; Mendlovitz, H.; Seim, H.; Lapham, L.; Magen, C.; Joye, S. B.; MacDonald, I. R.; Asper, V. L.; Diercks, A. R.

2016-02-01

In situ time-series measurements of light hydrocarbons, oxygen, temperature and bottom currents from landers and elevators in the benthic boundary layer (BBL) at multiple sites in the northern Gulf of Mexico reveal spatial and temporal variability in methane concentrations controlled by horizontal advection of methane-rich plumes originating from nearby natural oil and gas seeps. Multi-sensor systems deployed for several weeks within 1m of the seafloor at depths from 882 to 1622m revealed methane concentrations ranging from near atmospheric saturation (gas chromatography. Continuous laser sensor methane measurements from mini-landers deployed in September 2015 at our Horn Dome and Bush Hill sites featuring numerous gas seeps revealed methane concentrations ranging from data within the BBL and friction layer from untethered platforms provides important new opportunities for monitoring the impacts of natural seeps and accidental hydrocarbon releases. The instrumented approaches we have developed to simultaneously monitor methane sources and physical processes controlling plume development and transport will enable more effective responses to further accidental hydrocarbon releases.

Material Transport In The Inner Shelf Of The Northern Gulf Of Mexico

Science.gov (United States)

2016-12-01

portion of the WFS. Cold fronts associated with strong winter extratropical storms , also referred to as Cold Air Outbreaks (CAO), propagate west to...coastline in the northeastern Gulf of Mexico with both field observations and a numerical model simulation. In response to these extratropical storms ...and spring, extratropical cold air outbreaks frequently pass from the north, northwest across the nearly latitudinal coastline and experiment site

Modelling the temporal and spatial distribution of ecological variables in Beibu Gulf

Science.gov (United States)

Pan, H.; Huang, L.; Yang, S.; Shi, D.; Pan, W.

2017-12-01

Beibu Gulf is an important semi-enclosed gulf located in northern South China Sea. It is rich in natural resources and its coastal rim is undergoing a rapid economic growth in recent years. Study on the spatial and temporal distribution of ecological variables by the influence of physical and biological processes in Beibu Gulf can provide the theoretical basis for the utilization of resources and environmental protection. Based on the MEC three-dimensional hydrodynamic model, a nutrient-phytoplankton-zooplankton-detritus (NPZD) model was applied to simulate the distribution of ecological variables in Beibu Gulf. The result shows that the ecosystem in Beibu Gulf is significantly influenced by dynamic conditions. In autumn and winter, great amount of nutrient-rich water from western Guangdong coastal area passes through Qiongzhou Strait and flows into Beibu Gulf, with about 108.3×103 t of inorganic nitrogen and 3.7×103 t of phosphate annually, leading to phytoplankton bloom. In summer, most of the nutrients come from rivers so high concentrations of nutrients and chlorophyll-a appear on estuaries. The annual net nutrient inputs from South China Sea into Beibu Gulf are 66.6×103 t for inorganic nitrogen and 4.6×103 t for phosphate. Phytoplankton plays an important role in nutrients' refreshment: a) Absorption by the process of photosynthesis is the biggest nutrient sink. b) Cellular release from dead phytoplankton is the biggest source in inorganic budget, making up for 33.4% of nitrogen consumed by photosynthesis while the process of respiration is the biggest source in phosphate budget, making up for 32.4% of phosphorus consumed by photosynthesis. c) Mineralization from detritus is also a considerable supplement of inorganic nutrients. Overall, biological process has more influence than physical process on the nutrient cycle budget in Beibu Gulf. The comparison of the result with remote sensing and in-situ data indicates that the model is able to simulate the

Riverine organic matter composition and fluxes to Hudson Bay

Science.gov (United States)

Kuzyk, Z. Z. A.; Macdonald, R. W.; Goni, M. A.; Godin, P.; Stern, G. A.

2016-12-01

With warming in northern regions, many changes including permafrost degradation, vegetation alteration, and wildfire incidence will impact the carbon cycle. Organic carbon (OC) carried by river runoff to northern oceans has the potential to provide integrated evidence of these impacts. Here, concentrations of dissolved (DOC) and particulate (POC) OC are used to estimate terrestrial OC transport in 17 major rivers draining varied vegetative and permafrost conditions into Hudson Bay and compositional data (lignin and 14C) to infer OC sources. Hudson Bay lies just south of the Arctic Circle in Canada and is surrounded by a large drainage basin (3.9 × 106 km2) dominated by permafrost. Analysis of POC and DOC in the 17 rivers indicates that DOC dominates the total OC load. The southern rivers dominate. The Nelson and Churchill Rivers to the southwest are particularly important suppliers of OC partly because of large drainage basins but also perhaps because of impacts by hydroelectric development, as suggested by a 14C age of DOC in the Churchill River of 2800 years. Higher DOC and POC concentrations in the southern rivers, which have substantive areas only partially covered by permafrost, compared to northern rivers draining areas with complete permafrost cover, implies that warming - and hence permafrost thawing - will lead to progressively higher DOC and POC loads for these rivers. Lignin composition in the organic matter (S/V and C/V ratios) reveals mixed sources of OC consistent with the dominant vegetation in the river basins. This vegetation is organized by latitude with southern regions below the tree line enriched by woody gymnosperm sources (boreal forest) and northern regions enriched with organic matter from non-woody angiosperms (flowering shrubs, tundra). Acid/Aldehyde composition together with Δ14C data for selected DOC samples suggest that most of the lignin has undergone oxidative degradation, particularly the DOC component. However, high Δ14C ages

Pollutants from the Gulf War serve as water mass tracer in the Arabian Sea

Science.gov (United States)

Plähn, Olaf; Rhein, Monika; Fine, Rana A.; Sullivan, Kevin F.

In 1995, concentrations of the chlorofluorocarbon compound CFC-12 in the outflow water from the Persian Gulf were 8-40 fold higher than normally caused by air-sea gas exchange. At that time, the anomaly was restricted to the Gulf of Oman north of 20°N, while in 1998 the signal had spread southwestward to 12°N. The sources of this CFC-12 input of about 6400 kg are most likely the fire extinguishers and solvents used during and after the Gulf War in 1991. This CFC-12 signal is a new feature of the Persian Gulf Water (PGW) which can be used to track and quantify the spreading and dilution of PGW in the northern Indian Ocean. The contaminated PGW spreads southward with a mean velocity of 0.02-0.025 m s-1. At 20°N, the anomaly is diluted by a factor of more than two, and east of the island Socotra by a factor of four. A mean transport of less than 0.5·106 m³ s-1 is calculated for PGW assuming a mean dilution rate of 30% from the source signal in the Gulf of Oman to the western Arabian Sea.

Chromophoric Dissolved Organic Matter and Dissolved Organic Carbon from Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), Moderate Resolution Imaging Spectroradiometer (MODIS) and MERIS Sensors: Case Study for the Northern Gulf of Mexico

OpenAIRE

Blake A. Schaeffer; Thomas S. Bianchi; Eurico J. D'Sa; Christopher L. Osburn; Nazanin Chaichi Tehrani

2013-01-01

Empirical band ratio algorithms for the estimation of colored dissolved organic matter (CDOM) and dissolved organic carbon (DOC) for Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Moderate Resolution Imaging Spectroradiometer (MODIS) and MERIS ocean color sensors were assessed and developed for the northern Gulf of Mexico. Match-ups between in situ measurements of CDOM absorption coefficients at 412 nm (aCDOM(412)) with that derived from SeaWiFS were examined using two previously reported r...

Multiple Landslide-Hazard Scenarios Modeled for the Oakland-Berkeley Area, Northern California

Science.gov (United States)

Pike, Richard J.; Graymer, Russell W.

2008-01-01

With the exception of Los Angeles, perhaps no urban area in the United States is more at risk from landsliding, triggered by either precipitation or earthquake, than the San Francisco Bay region of northern California. By January each year, seasonal winter storms usually bring moisture levels of San Francisco Bay region hillsides to the point of saturation, after which additional heavy rainfall may induce landslides of various types and levels of severity. In addition, movement at any time along one of several active faults in the area may generate an earthquake large enough to trigger landslides. The danger to life and property rises each year as local populations continue to expand and more hillsides are graded for development of residential housing and its supporting infrastructure. The chapters in the text consist of: *Introduction by Russell W. Graymer *Chapter 1 Rainfall Thresholds for Landslide Activity, San Francisco Bay Region, Northern California by Raymond C. Wilson *Chapter 2 Susceptibility to Deep-Seated Landsliding Modeled for the Oakland-Berkeley Area, Northern California by Richard J. Pike and Steven Sobieszczyk *Chapter 3 Susceptibility to Shallow Landsliding Modeled for the Oakland-Berkeley Area, Northern California by Kevin M. Schmidt and Steven Sobieszczyk *Chapter 4 Landslide Hazard Modeled for the Cities of Oakland, Piedmont, and Berkeley, Northern California, from a M=7.1 Scenario Earthquake on the Hayward Fault Zone by Scott B. Miles and David K. Keefer *Chapter 5 Synthesis of Landslide-Hazard Scenarios Modeled for the Oakland-Berkeley Area, Northern California by Richard J. Pike The plates consist of: *Plate 1 Susceptibility to Deep-Seated Landsliding Modeled for the Oakland-Berkeley Area, Northern California by Richard J. Pike, Russell W. Graymer, Sebastian Roberts, Naomi B. Kalman, and Steven Sobieszczyk *Plate 2 Susceptibility to Shallow Landsliding Modeled for the Oakland-Berkeley Area, Northern California by Kevin M. Schmidt and Steven

Stable Isotopic Shifts in Fish Bones from Multiple Archeological Coastal Middens in Penobscot Bay, Maine

Science.gov (United States)

Harris, C.; Johnson, B.; Ambrose, W. G.; Bourque, B.; Dostie, P.; Crowley, E.

2010-12-01

The carbon and nitrogen stable isotope compositions of collagen extracted from well-preserved archeological fish bones has the potential to provide useful information on fish diets and food web dynamics over time. Previous work on the Turner Farm archaeological site in Penobscot Bay, Gulf of Maine, reveals significant shifts in fish diets have occurred since European colonization (post 1620’s). The objective of the present study was to analyze samples from other archaeological sites within Penobscot Bay to characterize the spatial extent of the isotopic shift measured at Turner Farm. Stratified cod, flounder, and sculpin bones were analyzed from eight coastal middens located approximately 50km apart from one another within Penobscot Bay. The bones were sampled from three time horizons (0kya, 0.5-1kya, and 2.2-2.4kya). All bone samples were demineralized in 0.2M HCl at 4°C for 2 to 7 days and then extracted in 0.25M NaOH at 4°C for 1 to 2 hours. After freeze-drying, the bulk isotopic composition of each sample was analyzed using the EA-IRMS. In all stratigraphic horizons analyzed, cod were more enriched in δ13C and δ15N than sculpin, and flounder were the most depleted in δ13C and δ15N . However, the isotopic offsets between the fish species decreased from 2.4kya to the present. The nitrogen isotope composition was relatively constant over time and space for all species, implying that trophic levels for the fishes analyzed have not changed significantly in Penobscot Bay for the last 2,400 years. The carbon isotope composition also appears to be constant spatially in Penobscot Bay, however, the modern signal was more depleted than the paleo signal in all three species. The difference between the modern and paleo δ13C is ~5‰ for cod and flounder, and ~9‰ for sculpin. These shifts may, in part, be explained by decreases in both primary producer and prey species diversity, as kelp forests replace eelgrass beds in the Gulf of Maine.

Spatial analysis of the etiology of amyotrophic lateral sclerosis among 1991 Gulf War veterans.

Science.gov (United States)

Miranda, Marie Lynn; Alicia Overstreet Galeano, M; Tassone, Eric; Allen, Kelli D; Horner, Ronnie D

2008-11-01

Veterans of the 1991 Gulf War have an increased risk of amyotrophic lateral sclerosis (ALS), but the etiology is unknown. This study sought to identify geographic areas with elevated risk for the later development of ALS among military personnel who served in the first Gulf War. A unified geographic information system (GIS) was constructed to allow analysis of secondary data on troop movements in the 1991 Gulf War theatre in the Persian Gulf region including Iraq, northern Saudi Arabia, and Kuwait. We fit Bayesian Poisson regression models to adjust for potential risk factors, including one relatively discrete environmental exposure, and to identify areas associated with elevated risk of ALS. We found that service in particular locations of the Gulf was associated with an elevated risk for later developing ALS, both before and after adjustment for branch of service and potential of exposure to chemical warfare agents in and around Khamisiyah, Iraq. Specific geographic locations of troop units within the 1991 Gulf War theatre are associated with an increased risk for the subsequent development of ALS among members of those units. The identified spatial locations represent the logical starting points in the search for potential etiologic factors of ALS among Gulf War veterans. Of note, for locations where the relative odds of subsequently developing ALS are among the highest, specific risk factors, whether environmental or occupationally related, have not been identified. The results of spatial models can be used to subsequently look for risk factors that follow the spatial pattern of elevated risk.

Environmental geology of Harrison Bay, northern Alaska

Science.gov (United States)

Craig, J.D.; Thrasher, G.P.

1982-01-01

The surficial and shallow subsurface geology of Harrison Bay on the Beaufort Sea coast was mapped as part of the U.S. Geological Survey's prelease evaluation for Outer Continental Shelf (OCS) Oil and Gas Lease Sale 71. During the 1980 summer season, approximately 1600 km of multisensored, high-resolution geophysical profile data were collected along a rectangular grid with 4.8 km line spacing. Interpretation of these data is presented on five maps showing bathymetry, sea-floor microrelief, ice-gouge characteristics, Holocene sediment thickness, and geologic structure to depths of approximately 1000 m. On a broad scale, the seafloor is shallow and almost flat, although microrelief features produced by sediment transport and ice-gouge processes typically vary up to several meters in amplitude. Microrelief bedforms related to hydraulic processes are predominant in water depths less than 12 m. Microrelief caused by ice gouging generally increases with water depth, reaching a maximum of 2 m or more in water depths beyond the 20 m isobath. This intensely gouged area lies beneath the shear zone between the seasonal landfast ice and the mobile polar ice pack. The thickness of recent (Holocene) sediment increases offshore, from 2 m near the Colville River delta to 30 m or more on the outer shelf. The thin Holocene layer is underlain by a complex horizon interpreted to be the upper surface of a Pleistocene deposit similar in composition to the present Arctic Coastal Plain. The base of the inferred Pleistocene section is interpreted to be a low-angle unconformity 100 m below sea level. Beneath this Tertiary-Quaternary unconformity, strata are interpreted to be alluvial fan-delta plain deposits corresponding to the Colville Group and younger formations of Late Cretaceous to Tertiary age. Numerous high-angle faults downthrown to the north trend across the survey area. With few exceptions, these faults terminate at or below the 100 m unconformity, suggesting that most tectonism

N and P as ultimate and proximate limiting nutrients in the northern Gulf of Mexico: implications for hypoxia reduction strategies

Directory of Open Access Journals (Sweden)

K. Fennel

2018-05-01

Full Text Available The occurrence of hypoxia in coastal oceans is a long-standing and growing problem worldwide and is clearly linked to anthropogenic nutrient inputs. While the need for reducing anthropogenic nutrient loads is generally accepted, it is costly and thus requires scientifically sound nutrient-reduction strategies. Issues under debate include the relative importance of nitrogen (N and phosphorus (P as well as the magnitude of the reduction requirements. The largest anthropogenically induced hypoxic area in North American coastal waters (of 15 000 ± 5000 km2 forms every summer in the northern Gulf of Mexico where the Mississippi and Atchafalaya rivers deliver large amounts of freshwater and nutrients to the shelf. A 2001 plan for reducing this hypoxic area by nutrient management in the watershed called for a reduction of N loads. Since then evidence of P limitation during the time of hypoxia formation has arisen, and a dual nutrient-reduction strategy for this system has been endorsed. Here we report the first systematic analysis of the effects of single and dual nutrient load reductions from a spatially explicit physical–biogeochemical model for the northern Gulf of Mexico. The model has been shown previously to skillfully represent the processes important for hypoxic formation. Our analysis of an ensemble of simulations with stepwise reductions in N, P, and N and P loads provides insight into the effects of both nutrients on primary production and hypoxia, and it allows us to estimate what nutrient reductions would be required for single and dual nutrient-reduction strategies to reach the hypoxia target. Our results show that, despite temporary P limitation, N is the ultimate limiting nutrient for primary production in this system. Nevertheless, a reduction in P load would reduce hypoxia because primary production is P limited in the region where density stratification is conducive to hypoxia development, but reductions in N load have

Surface circulation in the Gulf of Cadiz: Model and mean flow structure

Science.gov (United States)

Peliz, Alvaro; Dubert, Jesus; Marchesiello, Patrick; Teles-Machado, Ana

2007-11-01

The mean flow structure of the Gulf of Cadiz is studied using a numerical model. The model consists of a set of one-way nested configurations attaining resolutions on the order of 2.6 km in the region of the Gulf of Cadiz. In the large-scale configuration, the entrainment of the Mediterranean Water is parameterized implicitly through a nudging term. In medium- and small-scale nested configurations, the Mediterranean outflow is introduced explicitly. The model reproduces all the known features of the Azores Current and of the circulation inside the Gulf of Cadiz. A realistic Mediterranean Undercurrent is generated and Meddies develop at proper depths on the southwest tip of the Iberian slope. The hypothesis that the Azores Current may generate in association with the Mediterranean outflow (β-plume theories) is confirmed by the model results. The time-mean flow is dominated by a cyclonic cell generated in the gulf which expands westward and has transports ranging from 4 to 5 Sv. The connection between the cell and the Azores Current is analyzed. At the scale of the Gulf, the time-mean flow cell is composed by the westward Mediterranean Undercurrent, and by a counterflow running eastward over the outer edge of the Mediterranean Undercurrent deeper vein, as the latter is forced downslope. This counterflow feeds the entrainment at the depths of the Mediterranean Undercurrent and the Atlantic inflow at shallower levels. Coastward and upslope of this recirculation cell, a second current running equatorward all the way along the northern part of the gulf is revealed. This current is a very robust model result that promotes continuity between the southwestern Iberian coast and the Strait of Gibraltar, and helps explain many observations and recurrent SST features of the Gulf of Cadiz.

Reproductive data from Atlantic sharpnose sharks collected from Gulf of Mexico from 2011-02-24 to 2011-05-29 (NCEI Accession 0150634)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Reproductive data from Atlantic sharpnose sharks were collected from specimens captured throughout the northern Gulf of Mexico on various research vessels. Data...

Environmental assessment of coastal surface sediments at Tarut Island, Arabian Gulf (Saudi Arabia).

Science.gov (United States)

Youssef, Mohamed; El-Sorogy, Abdelbaset; Al Kahtany, Khaled; Al Otiaby, Naif

2015-07-15

Thirty eight surface sediments samples have been collected in the area around Tarut Island, Saudi Arabian Gulf to determine the spatial distribution of metals, and to assess the magnitude of pollution. Total concentrations of Fe, Mn, As, B, Cd, Co, Cr, Cu, Hg, Mo, Pb, Se, and Zn in the sediments were measured using ICP-MS (Inductively Coupled Plasma-Mass Spectrometer). Nature of sediments and heavy metals distribution reflect marked changes in lithology, biological activities in Tarut bay. Very high arsenic concentrations were reported in all studied locations from Tarut Island. The concentrations of Mercury are generally high comparing to the reported values from the Gulf of Oman, Red Sea. The concentrations of As and Hg exceeded the wet threshold safety values (MEC, PEC) indicating possible As and Hg contamination. Dredging and land filling, sewage, and oil pollution are the most important sources of pollution in the study area. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modeling the Seasonal and Interannual Variability of the Northern Gulf of California Salinity

Science.gov (United States)

2011-02-15

Schwartzlose (1979), Masas de agua del Golfo de California, Cienc . Mar., 6, 43–63. Argote, M. L., A. Amador, M. F. Lavı’n, and J. R. Hunter (1995...entrance of the Gulf of California, Mexico, Cienc . Mar., 26, 561–583. Enfield, D. B. (1987), The intraseasonal oscillation in eastern Pacific sea levels

Distribution and abundance by larval developmental stages of Symphurus williamsi (Pleuronectiformes: Cynoglossidae in the Gulf of California

Directory of Open Access Journals (Sweden)

Gerardo Aceves-Medina

2006-06-01

Full Text Available Distribution and abundance of tonguefish larvae (Symphurus williamsi were analyzed from collections made during ten oceanographic surveys in the Gulf of California between 1984 and 1988. Larvae were found mainly during the summer months and the highest abundances were located in the warmer southern and central regions of the Gulf, but they were scarce in the northern portion. High abundance of preflexion larvae occurred in areas where the sea surface temperature was between 29 and 32°C. Distribution patterns according to developmental stage suggest spatial ontogenic segregation with the early larvae in the ocean area of the central and southern regions of the Gulf. Based on abundance of preflexion larvae as well as on signs of a short egg period of this species, spawns may occur between early and mid summer.

Variability of Total and Pathogenic Vibrio parahaemolyticus Densities in Northern Gulf of Mexico Water and Oysters▿

Science.gov (United States)

Zimmerman, A. M.; DePaola, A.; Bowers, J. C.; Krantz, J. A.; Nordstrom, J. L.; Johnson, C. N.; Grimes, D. J.

2007-01-01

Vibrio parahaemolyticus is indigenous to coastal environments and a frequent cause of seafood-borne gastroenteritis in the United States, primarily due to raw-oyster consumption. Previous seasonal-cycle studies of V. parahaemolyticus have identified water temperature as the strongest environmental predictor. Salinity has also been identified, although it is evident that its effect on annual variation is not as pronounced. The effects of other environmental factors, both with respect to the seasonal cycle and intraseasonal variation, are uncertain. This study investigated intraseasonal variations of densities of total and pathogenic V. parahaemolyticus organisms in oysters and overlying waters during the summer of 2004 at two sites in the northern Gulf of Mexico. Regression analyses indicated significant associations (P turbidity in water and in oysters at the Mississippi site but not at the Alabama site. Pathogenic V. parahaemolyticus organisms in Mississippi oyster and water samples were detected in 56% (9 out of 16) and 78% (43 out of 55) of samples, respectively. In contrast, 44% (7 out of 16) of oyster samples and 30% (14 out of 47) of water samples from Alabama were positive. At both sites, there was greater sample-to-sample variability in pathogenic V. parahaemolyticus densities than in total V. parahaemolyticus densities. These data suggest that, although total V. parahaemolyticus densities may be very informative, there is greater uncertainty when total V. parahaemolyticus densities are used to predict the risk of infection by pathogenic V. parahaemolyticus than previously recognized. PMID:17921270

Variability of total and pathogenic Vibrio parahaemolyticus densities in northern Gulf of Mexico water and oysters.

Science.gov (United States)

Zimmerman, A M; DePaola, A; Bowers, J C; Krantz, J A; Nordstrom, J L; Johnson, C N; Grimes, D J

2007-12-01

Vibrio parahaemolyticus is indigenous to coastal environments and a frequent cause of seafood-borne gastroenteritis in the United States, primarily due to raw-oyster consumption. Previous seasonal-cycle studies of V. parahaemolyticus have identified water temperature as the strongest environmental predictor. Salinity has also been identified, although it is evident that its effect on annual variation is not as pronounced. The effects of other environmental factors, both with respect to the seasonal cycle and intraseasonal variation, are uncertain. This study investigated intraseasonal variations of densities of total and pathogenic V. parahaemolyticus organisms in oysters and overlying waters during the summer of 2004 at two sites in the northern Gulf of Mexico. Regression analyses indicated significant associations (P turbidity in water and in oysters at the Mississippi site but not at the Alabama site. Pathogenic V. parahaemolyticus organisms in Mississippi oyster and water samples were detected in 56% (9 out of 16) and 78% (43 out of 55) of samples, respectively. In contrast, 44% (7 out of 16) of oyster samples and 30% (14 out of 47) of water samples from Alabama were positive. At both sites, there was greater sample-to-sample variability in pathogenic V. parahaemolyticus densities than in total V. parahaemolyticus densities. These data suggest that, although total V. parahaemolyticus densities may be very informative, there is greater uncertainty when total V. parahaemolyticus densities are used to predict the risk of infection by pathogenic V. parahaemolyticus than previously recognized.

Potential Environmental Factors Affecting Oil-Degrading Bacterial Populations in Deep and Surface Waters of the Northern Gulf of Mexico.

Science.gov (United States)

Liu, Jiqing; Bacosa, Hernando P; Liu, Zhanfei

2016-01-01

chemistry, and initial bacterial community in selecting oil degraders and regulating their evolution in the northern Gulf of Mexico.

Cruise report for a seismic investigation of gas hydrates in the Mississippi Canyon region, northern Gulf of Mexico; cruise M1-98-GM

Science.gov (United States)

Cooper, Alan K.; Hart, Patrick E.; Pecher, Ingo

1998-01-01

During June 1998, the U.S. Geological Survey (USGS) and the University of Mississippi Marine Minerals Technology Center (MMTC) conducted a 12-day cruise in the Mississippi Canyon region of the Gulf of Mexico (Fig. 1). The R/V Tommy Munro, owned by the Marine Research Institute of the University of Southern Mississippi, was chartered for the cruise. The general objective was to acquire very high resolution seismic-reflection data across of the upper and middle continental slope (200-1200-m water depths) to study the acoustic character, distribution and potential effects of gas hydrates within the shallow subsurface, extending from the sea floor down to the base of the gas-hydrate stability zone. The Gulf of Mexico is well known for hydrocarbon resources that include petroleum and related gases. Areas of the Gulf that lie in waters deeper than about 250 m potentially have conditions (e.g., pressure, temperature, near-surface gas content, etc.) that are right for the shallow-subsurface formation of the ice-like substance (gas and water) known as gas hydrate (Kvenvolden, 1993). Gas hydrates have previously been sampled in sea-floor cores and observed as massive mounds in several parts of the northern Gulf, including the Mississippi Canyon region (e.g., Anderson et al., 1992). Extensive seismic data have been recorded in the Gulf, in support of commercial drilling efforts, but few very high resolution data exist in the public domain to aid in gas-hydrate studies. Studies of long-term interest include those on the resource potential of gas hydrates, the geologic hazards associated with dissociation and formation of hydrates, and the impact, if any, of gas-hydrate dissociation on atmospheric warming (i.e., via release of methane, a "greenhouse" gas). Several very high resolution seismic systems (surface-towed, deep-towed, and sea-floor) were used during the cruise to test the feasibility of using such data for detailed structural (geometric) and stratigraphic (physical

Sources of CO{sub 2} in the Gulf of Trieste (N. Adriatic). Stable Carbon Isotope Evidence

Energy Technology Data Exchange (ETDEWEB)

Ogrinc, N.; Zavadlav, S. [Department of Environmental Sciences, Jozef Stefan Institute, Ljubljana (Slovenia); Turk, D. [Department of Oceanography, Dalhousie University, Halifax, Nova Scotia (Canada); Lamont-Doherty Earth Observatory, Earth Institute at Columbia University, Palisades, NY (United States); Faganeli, J. [Marine Biological Station National Institute of Biology, Piran (Slovenia)

2013-07-15

In the present study the influence of freshwater intrusions on the net carbon dynamics in the Gulf of Trieste (northern Adriatic Sea) were investigated. Carbonate mineral weathering dominates the inorganic carbon geochemical flux of the N Adriatic rivers and thus the origin of dissolved inorganic carbon (DIC) in the gulf seawater. Based on {delta}{sup 13}C{sub DIC} values and isotopic mass balance it was estimated that rivers represents about 20% of DIC in spring, while the riverine contribution in autumn is less pronounced probably due to intensive water mixing. The results, therefore, suggest that river inputs play a significant role in the carbon cycling in the Gulf of Trieste due to mixing of higher DIC riverine water with lower seawater DIC. The observed higher summer {delta}{sup 13}C{sub DIC} values were due to more pronounced photosynthetic carbon fractionation. (author)

Swainson's Thrushes do not show strong wind selectivity prior to crossing the Gulf of Mexico.

Science.gov (United States)

Bolus, Rachel T; Diehl, Robert H; Moore, Frank R; Deppe, Jill L; Ward, Michael P; Smolinsky, Jaclyn; Zenzal, Theodore J

2017-10-27

During long-distance fall migrations, nocturnally migrating Swainson's Thrushes often stop on the northern Gulf of Mexico coast before flying across the Gulf. To minimize energetic costs, trans-Gulf migrants should stop over when they encounter crosswinds or headwinds, and depart with supportive tailwinds. However, time constrained migrants should be less selective, balancing costs of headwinds with benefits of continuing their migrations. To test the hypotheses that birds select supportive winds and that selectivity is mediated by seasonal time constraints, we examined whether local winds affected Swainson's Thrushes' arrival and departure at Ft. Morgan, Alabama, USA at annual, seasonal, and nightly time scales. Additionally, migrants could benefit from forecasting future wind conditions, crossing on nights when winds are consistently supportive across the Gulf, thereby avoiding the potentially lethal consequences of depleting their energetic reserves over water. To test whether birds forecast, we developed a movement model, calculated to what extent departure winds were predictive of future Gulf winds, and tested whether birds responded to predictability. Swainson's Thrushes were only slightly selective and did not appear to forecast. By following the simple rule of avoiding only the strongest headwinds at departure, Swainson's Thrushes could survive the 1500 km flight between Alabama and Veracruz, Mexico.

Assessing the Role of Dune Topography on a Fresh Water Lens of a Siliciclastic Barrier Along the Northern Gulf of Mexico

Science.gov (United States)

Anderson, C. P.; Carter, G. A.; Mooneyhan, D.

2013-12-01

Carlton P. Anderson, Gregory Carter, and David Mooneyhan University of Southern Mississippi Gulf Coast Geospatial Center Department of Geography and Geology Carlton.p.anderson@eagles.usm.edu The Mississippi-Alabama (MS-AL) barrier island chain consist of dynamic depositional landforms that constantly undergo changes in their evolutionary processes through changes in sea level, sediment supply, and weather events. These complex landscapes of the Northern Gulf of Mexico (NGOM) provide a chance to study their geomorphological progressions, which have been produced by sea level rise and fluvial processes throughout the Holocene. Studies on the freshwater lens of barriers have mainly concentrated on carbonate island settings with minimal focus to barriers with siliciclastic geology. The purpose of this study is to examine the relationship beach dune topography plays in the development and sustainability of the fresh water lens of Cat Island, Mississippi. Cat Island offers the opportunity to research a siliciclastic barrier along the NGOM where minimal anthropogenic activities have taken place. To determine the effect dune topography has on the fresh water lens, a transect of permanent water wells were used in conjunction with test wells at different sites throughout the north spit of the island, to establish the water table height above the ellipsoid (WGS 84), with vertical accuracies of 2 cm. Cross-sectional profiles of the dunes were also performed utilizing purposeful transects that intersected fresh water ponds in the dune-swale systems. These ponds provide water table elevations at the surface which were interpolated across the dunes for areas that lacked permanent well sites. To obtain survey-grade accuracies, a Trimble TSC3 receiver coupled with a R8 antennae RTK system were used. Salinity measurements were taken at test sites to determine the salt-to-freshwater interface. Results provide insights into how dune topography influences the fresh water lens of a

Tropical cyclone disasters in the Gulf of Thailand

Directory of Open Access Journals (Sweden)

Suphat Vongvisessomjai

2009-07-01

Full Text Available The origin of tropical cyclones in the South China Sea is over a vast deep sea, southeast of the Philippines. The severetropical cyclones in summer with northerly tracks attack the Philippines, China, Korea and Japan, while the moderate ones inthe rainy season with northwesterly tracks pass Vietnam, Laos and northern Thailand. In October, November and December, the tropical cyclones are weakened and tracks shift to a lower latitude passing the Gulf of Thailand. Tropical cyclone disasters in the Gulf of Thailand due to strong winds causing storm surges and big waves or heavy rainfall over high mountains in causing floods and land slides result in moderate damages and casualties. Analyses are made of six decades of data of tropical cyclones from 1951-2006 having averaged numbers of 3 and 13 in Thailand and the South China Sea respectively. Detailed calculation of surges and wave heights of the 5 disastrous tropical cyclones in the Gulf of Thailand reveal that the Upper Gulf of Thailand with a limited fetch length of about 100 km in north/south direction and about 100 km width in the east/west direction, resulted in a limited maximum wave height of 2.3-2.5 m and maximum storm surge height of 1.2 m generated by Typhoon Vae (1952, while the east coast, with longer fetch lengthbut still limited by the existence of its shoreline, resulted in an increased maximum wave height of 4 m and maximum storm surge height of 0.6 m in the Upper Gulf of Thailand generated by Typhoon Linda (1997. These are the Probable Maximum Cyclones here.The southern shoreline, with unlimited fetch length on the east by tropical cyclones approaching from the South China Sea, generated maximum wave height of 6-11 m by Typhoon Gay (1989, resulting in more casualties and damages. Note that storm surges on the southern shorelines with steep slopes are small due to the short distance of shallow shorelines in receiving wind stresses for piling up sea levels. These disasters can be

Monitoring the Northern San Francisco Bay Water Quality with Landsat-8. Nicholas B. Tufillaroa , and Curtiss O. Davisa. aOregon State University, Corvallis, OR, 97331, USA, nbt@coas.oregonstate.edu

Science.gov (United States)

Davis, C. O.; Tufillaro, N.

2016-02-01

Landsat-8's high spatial resolution ( 30 nm nominal), improved signal-to-noise (12bit digitizer) and expanded band set open up new applications for coastal and in-land waters. We use a recent ocean color processor for Landsat-8 created by Vanhellemont and Ruddick (RSE, 2015)to examine changes in the Northern San Francisco Bay, in particular looking for possiblechanges due to the on-going California drought. For instance, a temporary drought barrier to prevent salt water intrusion was placed during May of 2015 at West False River in the Sacramento-San Joaquin Delta. Using the new Landsat-8 ocean color products, we illustrate how to monitor changes in macro algae and plants (Sago pondweed (native), Curly pondweed (non-native)) in regions directly effected,such as the Franks Track region. Product maps using panchromatic enhancement ( 15 m resolution) andscene based atmospheric correction allow a detailed synoptic look every 16 days during theSpring, Summer, and Fall of 2015. This work is part of a larger NASA funded project aimed atimproving the modeling and predictive capabilities of the biogeochemical state for the San Francisco Bay(Davis, PI: Impacts of Population Growth on the San Francisco Bay and Delta Ecosystem, 2014-2017).

Application of a one-dimensional model to explore the drivers and lability of carbon in the northern Gulf of Mexico

Science.gov (United States)

A one-dimensional water quality model, Gulf of Mexico Dissolved Oxygen Model (GoMDOM-1D), was developed to simulate phytoplankton, carbon, nutrients, and dissolved oxygen in Gulf of Mexico. The model was calibrated and corroborated against a comprehensive set of field observation...

Geospatial risk assessment and trace element concentration in reef associated sediments, northern part of Gulf of Mannar biosphere reserve, Southeast Coast of India.

Science.gov (United States)

Krishnakumar, S; Ramasamy, S; Simon Peter, T; Godson, Prince S; Chandrasekar, N; Magesh, N S

2017-12-15

Fifty two surface sediments were collected from the northern part of the Gulf of Mannar biosphere reserve to assess the geospatial risk of sediments. We found that distribution of organic matter and CaCO 3 distributions were locally controlled by the mangrove litters and fragmented coral debris. In addition, Fe and Mn concentrations in the marine sediments were probably supplied through the riverine input and natural processes. The Geo-accumulation of elements fall under the uncontaminated category except Pb. Lead show a wide range of contamination from uncontaminated-moderately contaminated to extremely contaminated category. The sediment toxicity level of the elements revealed that the majority of the sediments fall under moderately to highly polluted sediments (23.07-28.84%). The grades of potential ecological risk suggest that predominant sediments fall under low to moderate risk category (55.7-32.7%). The accumulation level of trace elements clearly suggests that the coral reef ecosystem is under low to moderate risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Isla Guadalupe, Mexico (GUAX, SCIGN/PBO) a Relative Constraint for California Borderland and Northern Gulf of California Motions.

Science.gov (United States)

Gonzalez-Garcia, J. J.

2004-12-01

Using ITRF2000 as a common reference frame link, I analyzed survey mode and permanent GPS published results, together with SOPAC public data and results (http://sopac.ucsd.edu), in order to evaluate relative present day crustal deformation in California and northern Mexico. The crustal velocity field of Mexico (Marquez-Azua and DeMets, 2003) obtained from continuous GPS measurements conducted by Instituto Nacional de Geografia e Informatica (INEGI) for 1993-2001, was partially used. The preferred model for an instantaneous rigid motion between North-America and Pacific plates (NAPA), is obtained using results of Isla Guadalupe GPS surveys (1991-2002) giving a new constraint for Pacific plate (PA) motion (Gonzalez-Garcia et al., 2003). It produces an apparent reduction of 1 mm/yr in the absolute motion in the border zone between PA and North-America (NA) plates in this region, as compared with other GPS models (v.g. Prawirodirdjo and Bock, 2004); and it is 3 mm/yr higher than NNRNUVEL-1A. In the PA reference frame, westernmost islands from San Francisco (FARB), Los Angeles (MIG1), and Ensenada (GUAX); give current residuals of 1.8, 1.7 and 0.9 mm/yr and azimuths that are consistent with local tectonic setting, respectively. In the NA reference frame, besides the confirmation of 2 mm/yr E-W extension for the southern Basin and Range province in northern Mexico; a present day deformation rate of 40.5 mm/yr between San Felipe, Baja California (SFBC) and Hermosillo, Sonora, is obtained. This rate agrees with a 6.3 to 6.7 Ma for the "initiation of a full sea-floor spreading" in the northern Gulf of California. SFBC has a 7 mm/yr motion in the PA reference frame, giving then, a full NAPA theoretical absolute motion of 47.5 mm/yr. For Puerto Penasco, Sonora (PENA) there is a NAPA motion of 46.2 mm/yr and a residual of 1.2 mm/yr in the NA reference frame, this site is located only 75 km to the northeast from the Wagner basin center. For southern Isla Guadalupe (GUAX) there

Structural and geological analysis of the northern Pescadero basin: preliminary results based on the analysis of 2D multichannel seismic reflection profiles

Science.gov (United States)

Spelz, R. M.; Ramirez-Zerpa, N. A.; Gonzalez-Fernandez, A.; Yarbuh, I.; Contreras, J.

2017-12-01

The Pacific-North America plate boundary along the Gulf of California is characterized by an array of right-stepping, right-lateral, transform faults connecting a series of pull-apart basins distributed along the gulf axis. Altogether, these structures accommodate an oblique-divergent component of deformation characterizing the modern tectonic regime along the gulf. The northern Pescadero complex, in the southern Gulf of California, is one of the deepest and probably least studied transtensional fault-termination basins in the gulf. The complex is bounded to the north and south by Atl and Farallon transform faults, respectively, and consists of two asymmetric, rhomboidal-shaped, basins with a series of intrabasinal high-angle normal faults and ramps connecting their depocenters. In this study we present preliminary results derived from the processing and analysis of 400 km of seismic reflection profiles, collected in 2006 onboard the R/V Francisco de Ulloa in northern Pescadero, providing new insights into the geology and internal structure of the basin. Northern Pescadero is a deep and narrow basin characterized by a maximum sedimentary infill of 1 km, and depths to the basin floor exceeding 3500 m. Deformation is chiefly accommodated by an array of self-parallel half-graben structures that appear to grow towards the northern flank of the basin. Faults-scarps located farther from the deformation axis appear to be more degraded, suggesting a progressively younger age of the half-grabens near the basin's depocenter. Another important feature revealed in the seismic images is the lack of sediments on top of the crystalline basement that floors the narrow central portion of the basin. In this area the reflectors at the basin's floor show a pronounced increase in amplitude and coherence, indicating the emplacement of magmatic extrusions. Likewise, in those areas with the greater sediment infill, the occurrence of high-amplitude reflectors, located 150 m below the

Atmospheric deposition of organochlorine contaminants to Galveston Bay, Texas

Science.gov (United States)

Park, June-Soo; Wade, Terry L.; Sweet, Stephen

Atmospheric monitoring of PCBs and chlorinated pesticides (e.g., HCHs, chlordanes, and DDTs) in Galveston Bay was conducted at Seabrook, Texas. Air and wet deposition samples were collected from 2 February 1995 and continued through 6 August 1996. Vapor total PCB ( tPCB) concentrations in air ranged from 0.21 to 4.78 ng m -3 with a dominance of tri-chlorinated PCBs. Dissolved tPCBs in rain ranged from 0.08 to 3.34 ng l -1, with tetra-chlorinated PCBs predominating. The predominant isomers found in air and rain were α- and γ-HCH, α- and γ-chlordanes, 4,4'-DDT, and dieldrin. The concentrations of PCBs and pesticides in the air and rain revealed no clear seasonal trend. Elevated levels of PCBs in the air occurred when temperatures were high and wind came from urban and industrialized areas (S, SW, NW, and W of the site). Concentrations of HCHs were elevated in April, May, and October, perhaps due to local and/or regional applications of γ-HCH (lindane). Other pesticides showed no notable temporal variation. When winds originated from the Gulf of Mexico (southeasterly), lower concentrations of organochlorines were detected in the air. The direct deposition rate (wet+dry) of PCBs to Galveston Bay (6.40 μg m -2 yr -1) was significantly higher than that of pesticides by a factor of 5-10. The net flux from gas exchange estimated for PCBs was from Galveston Bay water to the atmosphere (78 μg m -2 yr -1). Gas exchange of PCBs from bay water to the atmosphere was the dominant flux.

Organchlorine content and shell thickness in brown booby (Sula leucogaster) eggs in the Gulf of California and the southern Pacific coast of Mexico

Energy Technology Data Exchange (ETDEWEB)

Mellink, Eric, E-mail: emellink@cicese.m [Departamento de Biologia de la Conservacion, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, B.C. Carretera Tijuana-Ensenada Km. 107, 22860 Ensenada, B.C. (Mexico); Riojas-Lopez, Monica E., E-mail: meriojas@cucba.udg.m [Departamento de Ecologia, Centro Universitario de Ciencias Biologicas y Agropecuarias, Universidad de Guadalajara, Km. 15.5 Carretera a Nogales, 45100 Zapopan, Jalisco (Mexico); Luevano-Esparza, Jaime, E-mail: jluevano@cicese.m [Departamento de Biologia de la Conservacion, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, B.C. Carretera Tijuana-Ensenada Km. 107, 22860 Ensenada, B.C. (Mexico)

2009-07-15

We determined egg concentrations of organochlorines and thickness of eggshells from brown boobies at eight colonies ranging from the northern Gulf of California to southern Mexico. The only common residue was that of DDE, which was found in almost all eggs. DDE content apparently reflected pre-1990 DDT use in nearby agricultural areas and, at one site, intensive mosquito control for high-end tourism development. There were no inter-colony differences in eggshell thickness, and variation in this variable likely reflected individual bird characteristics and/or individual feeding source. This variable was not a good proxy to DDE exposure of brown boobies, under current DDE levels in the brown booby trophic chain. In the northern Gulf of California, eggshell thickness has recovered to pre-DDT conditions. Our data indicate that the Gulf of California and southwestern coast of Mexico have a healthy near-shore marine environment, as far as organochlorines are concerned. - Wide-range, current picture of organochlorine presence in the environment along the western coast of Mexico.

Organchlorine content and shell thickness in brown booby (Sula leucogaster) eggs in the Gulf of California and the southern Pacific coast of Mexico

International Nuclear Information System (INIS)

Mellink, Eric; Riojas-Lopez, Monica E.; Luevano-Esparza, Jaime

2009-01-01

We determined egg concentrations of organochlorines and thickness of eggshells from brown boobies at eight colonies ranging from the northern Gulf of California to southern Mexico. The only common residue was that of DDE, which was found in almost all eggs. DDE content apparently reflected pre-1990 DDT use in nearby agricultural areas and, at one site, intensive mosquito control for high-end tourism development. There were no inter-colony differences in eggshell thickness, and variation in this variable likely reflected individual bird characteristics and/or individual feeding source. This variable was not a good proxy to DDE exposure of brown boobies, under current DDE levels in the brown booby trophic chain. In the northern Gulf of California, eggshell thickness has recovered to pre-DDT conditions. Our data indicate that the Gulf of California and southwestern coast of Mexico have a healthy near-shore marine environment, as far as organochlorines are concerned. - Wide-range, current picture of organochlorine presence in the environment along the western coast of Mexico.

Cold-seep carbonates of the middle and lower continental slope, northern Gulf of Mexico

Science.gov (United States)

Roberts, Harry H.; Feng, Dong; Joye, Samantha B.

2010-11-01

Authigenic carbonates from cold seeps on the middle and lower continental slope of the northern Gulf of Mexico (GOM) exhibit a wide range of mineralogical and stable isotopic compositions. These carbonates consist of concretions and nodules in surface sediments, hardgrounds of crusts and isolated slabs, and mounded buildups of blocks and slabs of up to over 10 meters in relief above the surrounding seafloor. Mineralogically, the carbonates are dominated by high-Mg calcite (HMC) and aragonite. However, low levels (oil, seawater CO2, and 13C-enriched residual CO2 from methanogenesis. A similarly large variability in δ18O values (2.5 to 6.7‰ PDB) demonstrates the geochemical complexity of the slope, with some samples pointing toward an 18O-enriched oxygen source that is possibly related to advection of 18O-enriched formation water and/or to the decomposition of gas hydrate. A considerable range of mineralogical and isotopic variations in cold-seep carbonate composition was noted even within individual study sites. However, common trends occur across multiple geographic areas. This situation suggests that local controls on fluid and gas flux, types of seep hydrocarbons, the presence or absence of gas hydrate in the near-surface sediment, and chemosynthetic communities, as well as the temporal evolution of the local hydrocarbon reservoir, all may play a part in determining carbonate mineralogy and isotope geochemistry. The carbon isotope data clearly indicate that between-site variation is greater than within-site variation. Seep carbonates formed on the middle and lower continental slope of the GOM do not appear to be substantially different from those found on the upper slope (<1000-m water depth). The highly variable fluids and gases that leave their geochemical imprints on seep carbonate of the middle and lower continental slope are similar to their outer shelf and upper slope counterparts.

Prevalence of Gulf war veterans who believe they have Gulf war syndrome: questionnaire study

Science.gov (United States)

Chalder, T; Hotopf, M; Unwin, C; Hull, L; Ismail, K; David, A; Wessely, S

2001-01-01

Objectives To determine how many veterans in a random sample of British veterans who served in the Gulf war believe they have “Gulf war syndrome,” to examine factors associated with the presence of this belief, and to compare the health status of those who believe they have Gulf war syndrome with those who do not. Design Questionnaire study asking British Gulf war veterans whether they believe they have Gulf war syndrome and about symptoms, fatigue, psychological distress, post-traumatic stress, physical functioning, and their perception of health. Participants 2961 respondents to questionnaires sent out to a random sample of 4250 Gulf war veterans (69.7%). Main outcome measure The proportion of veterans who believe they have Gulf war syndrome. Results Overall, 17.3% (95% confidence interval 15.9 to 18.7) of the respondents believed they had Gulf war syndrome. The belief was associated with the veteran having poor health, not serving in the army when responding to the questionnaire, and having received a high number of vaccinations before deployment to the Gulf. The strongest association was knowing another person who also thought they had Gulf war syndrome. Conclusions Substantial numbers of British Gulf war veterans believe they have Gulf war syndrome, which is associated with psychological distress, a high number of symptoms, and some reduction in activity levels. A combination of biological, psychological, and sociological factors are associated with the belief, and these factors should be addressed in clinical practice. What is already known on this topicThe term Gulf war syndrome has been used to describe illnesses and symptoms experienced by veterans of the 1991 Gulf warConcerns exist over the validity of Gulf war syndrome as a unique entityWhat this study adds17% of Gulf war veterans believe they have Gulf war syndromeHolding the belief is associated with worse health outcomesKnowing someone else who believes they have Gulf war syndrome and receiving

Evaluation of seismic hazard of the Gökova bay in terms of seismotectonics

Energy Technology Data Exchange (ETDEWEB)

Erkoç, Ebru Aktepe, E-mail: ebru.aktepe@deu.edu.tr [The Graduate School of Natural and Applied Sciences, Dokuz Eylül University, İzmir-Turkey (Turkey); Uluğ, Atilla, E-mail: atilla.ulug@deu.edu.tr [Institute of Marine Science and Technology, Dokuz Eylül University, İzmir-Turkey (Turkey)

2016-04-18

While discovering the seismicity of our country, knowing the array of earthquake occurrence which reflects the characteristic tectonic features of each region makes vital contributions to the earthquakes that have occurred and to the pursuit of the processes which might occur in the future. When considering the region’s seismic activity, the presence of active faults that create earthquake within the bay is obvious. Many active fault parts in the Gulf of Gökova region continues their seismic activity with the opening effect that is generally prevailing in Western Anatolia. The region has generally been continuing its seismic activity under the control of normal faults. Considering the marine studies that are made and marine continuity of the faults which are on land in addition to the seismological and tectonic studies, the determination of seismic hazard in the Gulf of Gökova and its surroundings is also important in terms of introducing the earthquake scenarios with minimized errors.

Evaluation of seismic hazard of the Gökova bay in terms of seismotectonics

International Nuclear Information System (INIS)

Erkoç, Ebru Aktepe; Uluğ, Atilla

2016-01-01

While discovering the seismicity of our country, knowing the array of earthquake occurrence which reflects the characteristic tectonic features of each region makes vital contributions to the earthquakes that have occurred and to the pursuit of the processes which might occur in the future. When considering the region’s seismic activity, the presence of active faults that create earthquake within the bay is obvious. Many active fault parts in the Gulf of Gökova region continues their seismic activity with the opening effect that is generally prevailing in Western Anatolia. The region has generally been continuing its seismic activity under the control of normal faults. Considering the marine studies that are made and marine continuity of the faults which are on land in addition to the seismological and tectonic studies, the determination of seismic hazard in the Gulf of Gökova and its surroundings is also important in terms of introducing the earthquake scenarios with minimized errors.

Alkane Hydroxylase Gene (alkB Phylotype Composition and Diversity in Northern Gulf of Mexico Bacterioplankton

Directory of Open Access Journals (Sweden)

Conor Blake Smith

2013-12-01

Full Text Available Natural and anthropogenic activities introduce alkanes into marine systems where they are degraded by alkane hydroxylases expressed by phylogenetically diverse bacteria. Partial sequences for alkB, one of the structural genes of alkane hydroxylase, have been used to assess the composition of alkane-degrading communities, and to determine their responses to hydrocarbon inputs. We present here the first spatially extensive analysis of alkB in bacterioplankton of the northern Gulf of Mexico (nGoM, a region that experiences numerous hydrocarbon inputs. We have analyzed 401 partial alkB gene sequences amplified from genomic extracts collected during March 2010 from 17 water column samples that included surface waters and bathypelagic depths. Previous analyses of 16S rRNA gene sequences for these and related samples have shown that nGoM bacterial community composition and structure stratify strongly with depth, with distinctly different communities above and below 100 m. Although we hypothesized that alkB gene sequences would exhibit a similar pattern, PCA analyses of operational protein units (OPU indicated that community composition did not vary consistently with depth or other major physical-chemical variables. We observed 22 distinct OPUs, one of which was ubiquitous and accounted for 57% of all sequences. This OPU clustered with alkB sequences from known hydrocarbon oxidizers (e.g., Alcanivorax and Marinobacter. Some OPUs could not be associated with known alkane degraders, however, and perhaps represent novel hydrocarbon-oxidizing populations or genes. These results indicate that the capacity for alkane hydrolysis occurs widely in the nGoM, but that alkane degrader diversity varies substantially among sites and responds differently than bulk communities to physical-chemical variables.

Caridean shrimps (Crustacea, Decapoda) from seagrass habitats in Hansa Bay, Papua New Guinea

NARCIS (Netherlands)

Grave, de Sammy

1999-01-01

Five species of caridean shrimps collected from seagrass habitats at Hansa Bay, on the northern coastline of Papua New Guinea are reported. Four species are new to the fauna of Papua New Guinea. Morphological details of Nikoides danae, Latreutes pymoeus and L. porcinus are discussed and compared to

Venezuelan Equine Encephalitis Virus Activity in the Gulf Coast Region of Mexico, 2003–2010

Science.gov (United States)

Adams, A. Paige; Navarro-Lopez, Roberto; Ramirez-Aguilar, Francisco J.; Lopez-Gonzalez, Irene; Leal, Grace; Flores-Mayorga, Jose M.; Travassos da Rosa, Amelia P. A.; Saxton-Shaw, Kali D.; Singh, Amber J.; Borland, Erin M.; Powers, Ann M.; Tesh, Robert B.; Weaver, Scott C.; Estrada-Franco, Jose G.

2012-01-01

Venezuelan equine encephalitis virus (VEEV) has been the causative agent for sporadic epidemics and equine epizootics throughout the Americas since the 1930s. In 1969, an outbreak of Venezuelan equine encephalitis (VEE) spread rapidly from Guatemala and through the Gulf Coast region of Mexico, reaching Texas in 1971. Since this outbreak, there have been very few studies to determine the northward extent of endemic VEEV in this region. This study reports the findings of serologic surveillance in the Gulf Coast region of Mexico from 2003–2010. Phylogenetic analysis was also performed on viral isolates from this region to determine whether there have been substantial genetic changes in VEEV since the 1960s. Based on the findings of this study, the Gulf Coast lineage of subtype IE VEEV continues to actively circulate in this region of Mexico and appears to be responsible for infection of humans and animals throughout this region, including the northern State of Tamaulipas, which borders Texas. PMID:23133685

Bioinvasion in a Brazilian bay: filling gaps in the knowledge of southwestern Atlantic biota.

Directory of Open Access Journals (Sweden)

Barbara L Ignacio

2010-09-01

Full Text Available Biological invasions are a major cause of global species change. Nevertheless, knowledge about the distribution and ecology of introduced species is regionally biased, and many gaps in knowledge exist for most developing countries.To study the zoobenthos on the hard substratum of the Ilha Grande Bay, a survey was conducted on both natural and artificial substrata at three depths and seven sites. The species recorded were classified as native, cryptogenic or introduced. Multivariate analyses were conducted to assess the prevalence of introduced species in these communities and to compare the distribution of species on natural and artificial substrata of this bay to identify possible discrepancies in habitat use. Of the 61 species, 25 were cryptogenic, 10 were introduced and 26 were native. Similar numbers of introduced species were found on both natural and artificial substrata, though the community composition was significantly different between them. We also compared the species composition of the Ilha Grande Bay survey to other inventories taken around the world. The highest similarities were found between the Ilha Grande Bay inventory and the Atlantic coastal region (Tampa Bay, USA and the Gulf of Mexico, American Samoa and Pearl Harbor (USA inventories.This study presents the first published comprehensive list of hard substratum sessile marine invertebrate species in a Brazilian bay. The high percentage of cryptogenic species reveals gaps in both zoological records and information on introduced species for the Brazilian coast. The introduced species successfully colonized different sites in the Ilha Grande Bay, including both natural and artificial substrata. In addition, we find that artificial structures may not be good surrogates for natural rocky shores and may represent an ecological threat. Comparisons with other inventories suggest a history of broad-scale invasion, though more evidence is needed to support this conclusion.

Wetland Responses to Sea Level Rise in the Northern Gulf of Mexico

Science.gov (United States)

Alizad, K.; Bilskie, M. V.; Hagen, S. C.; Medeiros, S. C.; Morris, J. T.

2016-12-01

Coastal regions are vulnerable to flood risk due to climate change, sea level rise, and wetland losses. The Northern Gulf of Mexico (NGOM) is a region in which extreme events are projected to be more intense under climate change and sea level rise scenarios [Wang et al., 2013; Bilskie et al., 2014]. Considering increased frequency and intensity of coastal flooding, wetlands are valuable natural resources that protect shorelines by dissipating waves and storm surges [Costanza et al., 2008]. Therefore, it is critical to investigate the response of salt marsh systems in different estuaries to sea level rise in the NGOM and their effects on storm surges to inform coastal managers to choose effective restoration plans. This research applies the coupled Hydro-MEM model [Alizad et al., 2016] to study three different estuarine systems in the NGOM. The model incorporates both sea level rise rate and feedbacks between physics and biology by coupling a hydrodynamic (ADCIRC) and salt marsh (MEM) model. The results of the model provide tidal hydrodynamics and biomass density change under four sea level rise projections during a 100-year period. The results are used to investigate marsh migration path in the estuarine systems. In addition, this study shows how marsh migration and biomass density change can impact storm surge modeling. The results imply the broader impacts of sea level rise on the estuarine systems in the NGOM. ReferencesAlizad, K., S. C. Hagen, J. T. Morris, P. Bacopoulos, M. V. Bilskie, J. Weishampel, and S. C. Medeiros (2016), A coupled, two-dimensional hydrodynamic-marsh model with biological feedback, Ecological Modeling, 327, 29-43. Bilskie, M. V., S. C. Hagen, S. C. Medeiros, and D. L. Passeri (2014), Dynamics of sea level rise and coastal flooding on a changing landscape, Geophysical Research Letters, 41(3), 927-934. Costanza, R., O. Pérez-Maqueo, M. L. Martinez, P. Sutton, S. J. Anderson, and K. Mulder (2008), The Value of Coastal Wetlands for Hurricane

Hydrological functions of a mine-impacted and natural peatland-dominated watershed, James Bay Lowland

OpenAIRE

Leclair, Melissa; Whittington, Pete; Price, Jonathan

2015-01-01

Study region: This study was conducted in Northern Ontario, Canada, in the middle of the Hudson-James Bay. Lowland: one of the world’s largest wetland complexes. Study focus: Northern latitudes are expected to be the most impacted by climate change in the next century and adding to this stressor are increased mineral exploration activities, such as the De Beers Victor Mine, a large open-pit diamond mine. Because of the extremely low relief and presence of marine sediments, horizontal runof...

Spatio-temporal variability of internal waves in the northern Gulf of Mexico studied with the Navy Coastal Ocean Model, NCOM

Science.gov (United States)

Cambazoglu, M. K.; Jacobs, G. A.; Howden, S. D.; Book, J. W.; Arnone, R.; Soto Ramos, I. M.; Vandermeulen, R. A.; Greer, A. T.; Miles, T. N.

2016-02-01

Internal waves enhance mixing in the upper ocean, transport nutrients and plankton over the water column and across the shelf from deeper waters to shallower coastal areas, and could also transport pollutants such as hydrocarbons onshore during an oil spill event. This study aims to characterize internal waves in the northern Gulf of Mexico (nGoM) and investigate the possible generation and dissipation mechanisms using a high-resolution (1-km) application of the Navy Coastal Ocean Model (NCOM). Three dimensional model products are used to detect the propagation patterns of internal waves. The vertical structure of internal waves is studied and the role of stratification is analyzed by looking at the temperature, salinity and velocity variations along the water column. The model predictions suggest the generation of internal waves on the continental shelf, therefore the role of ocean bottom topography interacting with tides and general circulation features such as the Loop Current Eddy front, on the internal wave generation will be discussed. The time periods of internal wave occurrences are identified from model predictions and compared to satellite ocean color imagery. Further data analysis, e.g. Fourier analysis, is implemented to determine internal wavelengths and frequencies and to determine if the response of internal waves are at tidal periods or at different frequencies. The atmospheric forcing provided to NCOM and meteorological data records are analyzed to define the interaction between wind forcing and internal wave generation. Wavelet analysis characterizes the ocean response to atmospheric events with periodic frequencies. Ocean color satellite imagery was used to visualize the location of the Mississippi river plume (and other oceanic features) and compared to the model predictions because the enhanced stratification from freshwater plumes which propagate across the Mississippi Bight can provide favorable conditions in coastal waters for internal wave

Hydrographic Conditions in the Gulf of Carpentaria During Australian Monsoon Experiment

Science.gov (United States)

Inoue, M.; Steinberg, C.; Wolanski, E.; Ridd, P.

2002-12-01

Gulf of Carpentaria located in the northern Australia, is a shallow wide basin with the deepest bottom depths of approximately 60 m. It is connected to Arafura Sea to the north and west, and to the Torres Strait to the east. Hydrographic surveys of the Gulf of Carpentaria were carried out in January and March, 1987 as part of Australian Monsoon Experiment. During the January survey, Tropical Cyclone (TC) Irma was formed in the Gulf of Carpentaria. An east-west CTD section at 13o52'S was occupied twice, one prior to and during, and the other after the formation of TC Irma. In addition, two post-Irma east-west sections were occupied at 12o40'S and 11o30'S. The pre-cyclone section indicates a well-defined stratified two-layer system, while the post-cyclone sections show deepening of the surface warm layer due to significant mixing by TC Irma. Overall, significant cooling of near surface warm water on the order of more than 1oC was observed. Significant heat loss estimated for the water column has presumably contributed toward the development of TC Irma. In February 1987, TC Jason was formed in the gulf. During the March survey, two east-west CTD sections were occupied at 11o30'S and 13o52'S. The March survey reveals notable warming of the bottom water. Detailed discussion of the CTD data from the two cruises will be presented.

Distribution and spectral characteristics of chromophoric dissolved organic matter in a coastal bay in northern China.

Science.gov (United States)

Li, Guiju; Liu, Jing; Ma, Yulan; Zhao, Ruihua; Hu, Suzheng; Li, Yijie; Wei, Hao; Xie, Huixiang

2014-08-01

The absorption spectra of chromophoric dissolved organic matter (CDOM), along with general physical, chemical and biological variables, were determined in the Bohai Bay, China, in the springs of 2011 and 2012. The absorption coefficient of CDOM at 350 nm (a350) in surface water ranged from 1.00 to 1.83 m⁻¹ (mean: 1.35 m⁻¹) in May 2011 and from 0.78 to 1.92 m⁻¹ (mean: 1.19 m⁻¹) in April 2012. Little surface-bottom difference was observed due to strong vertical mixing. The a350 was weakly anti-correlated to salinity but positively correlated to chlorophyll a (Chl-a) concentration. A shoulder over 260-290 nm, suggestive of biogenic molecules, superimposed the overall pattern of exponentially decreasing CDOM absorption with wavelength. The wavelength distribution of the absorption spectral slope manifested a pronounced peak at ca. 300 nm characteristic of algal-derived CDOM. All a250/a365 ratios exceeded 6, corresponding to CDOM molecular weights (Mw) of less than 1 kDa. Spectroscopically, CDOM in the Bohai Bay differed substantively from that in the Haihe River, the bay's dominant source of land runoff; photobleaching of the riverine CDOM enlarged the difference. Results point to marine biological production being the principal source of CDOM in the Bohai Bay during the sampling seasons. Relatively low runoff, fast dilution, and selective photodegradation are postulated to be among the overarching elements responsible for the lack of terrigenous CDOM signature in the bay water. Copyright © 2014. Published by Elsevier B.V.

HYPOXIA IN THE GULF OF MEXICO: ASSESSING AND MANAGING RISKS FROM NONPOINT SOURCE POLLUTANTS IN THE MISSISSIPPI RIVER BASIN

Science.gov (United States)

. Hypoxia is the condition in which dissolved oxygen levels are below that necessary to sustain most animal life. The largest zone of oxygen depletion in U.S. coastal waters is found in the northern Gulf of Mexico (NGOM) on the Louisiana/Texas continental shelf. In response to...

Airborne gamma-ray spectrometer and magnetometer survey Coos Bay, Oregon. Final report

International Nuclear Information System (INIS)

1981-05-01

During the months of August, September, and October of 1980, Aero Service Division Western Geophysical Company of America conducted an airborne high sensitivity gamma-ray spectrometer and magnetometer survey over ten (10) areas over northern California and southwestern Oregon. These include the 2 0 x 1 0 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 1 0 x 2 0 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Coos Bay, Oregon, map area. Line spacing was generally six miles for east/west traverses and eighteen miles for north/south tie lines over the northern one-half of the area. Traverses and tie lines were flown at three miles and twelve miles respectively over the southern one-half of the area. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 863.8 line miles are in this quadrangle

Over 100 years of environmental change recorded by foraminifers and sediments in a large Gulf of Mexico estuary, Mobile Bay, AL, USA

Science.gov (United States)

Osterman, Lisa E.; Smith, Christopher G.

2012-01-01

The marine microfauna of Mobile Bay has been profoundly influenced by the development and expansion of the primary shipping channel over the last ˜100 years. Foraminifers and sediments from seven box cores with excess lead-210 chronology document that channel dredging and spoil disposal have altered circulation, reduced estuarine mixing, changed sedimentation patterns, and caused a faunal turnover within the bay. Beginning in the late 1800s, changes in estuarine mixing allowed for greater low-pH freshwater influence in the bay, and ultimately began environmental changes that resulted in the loss of calcareous foraminifers. By the early 1900s, box cores throughout Mobile Bay record a ˜ 100-year trend of increasing calcareous test dissolution that continues to the present. Since the completion of the current shipping channel in the 1950s, restricted tidal flushing and increased terrestrial organic matter, documented by carbon-to-nitrogen ratios, stimulated an increase in agglutinated foraminiferal densities. However, in deeper areas of the bay, hypoxic water has negatively impacted the marine microfauna. Comparisons of the present-day foraminiferal assemblage with foraminifers collected in the early 1970s indicate that the continued biologic loss of calcareous foraminifers in the bay has allowed the introduction of a new agglutinated foraminiferal species into the bay.

The movement and implications of the Ganges-Bramhaputra runoff on entering the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Shetye, S.R.

The Ganges-Brahmaputra rivers discharge annually approximately 10 sup(2) m sup(3) of freshwater into the Bay of Bengal at its northern end. We propose that the spread of this water, accompaniEd. by mixing with the ambient waters, occurs in three...

Macroalgae in the coral reefs of Eilat (Gulf of Aqaba, Red Sea) as a possible indicator of reef degradation

International Nuclear Information System (INIS)

Bahartan, Karnit; Zibdah, Mohammad; Ahmed, Yousef; Israel, Alvaro; Brickner, Itzchak; Abelson, Avigdor

2010-01-01

The current state of health of the coral reefs in the northern Gulf of Aqaba (Red Sea), notably the Eilat reefs, is under debate regarding both their exact condition and the causes of degradation. A dearth of earlier data and unequivocal reliable indices are the major problems hinder a clear understanding of the reef state. Our research objective was to examine coral-algal dynamics as a potential cause and an indication of reef degradation. The community structure of stony corals and algae along the northern Gulf of Aqaba reveal non-seasonal turf algae dominancy in the shallow Eilat reefs (up to 72%), while the proximate Aqaba reefs present negligible turf cover (<6%). We believe that turf dominancy can indicate degradation in these reefs, based on the reduction in essential reef components followed by proliferation of perennial turf algae. Our findings provide further evidence for the severe state of the Eilat coral reefs.

Earthquakes and faults in the San Francisco Bay area (1970-2003)

Science.gov (United States)

Sleeter, Benjamin M.; Calzia, James P.; Walter, Stephen R.; Wong, Florence L.; Saucedo, George J.

2004-01-01

The map depicts both active and inactive faults and earthquakes magnitude 1.5 to 7.0 in the greater San Francisco Bay area. Twenty-two earthquakes magnitude 5.0 and greater are indicated on the map and listed chronologically in an accompanying table. The data are compiled from records from 1970-2003. The bathymetry was generated from a digital version of NOAA maps and hydrogeographic data for San Francisco Bay. Elevation data are from the USGS National Elevation Database. Landsat satellite image is from seven Landsat 7 Enhanced Thematic Mapper Plus scenes. Fault data are reproduced with permission from the California Geological Survey. The earthquake data are from the Northern California Earthquake Catalog.

Atlas of ecologically and commercially important areas in the southern Gulf of St. Lawrence

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-10-01

This atlas provides useful baseline information for the environmental assessment of petroleum project proposals relative to sensitive areas and critical periods of fisheries resources in the southern Gulf of St. Lawrence. The southern boundary of the Gulf of St. Lawrence is bounded by the shores of western Cape Breton, southeastern New Brunswick and northern Nova Scotia. It is characterized as a coastal marine ecosystem because of the predominating effects of the rivers, but deeper areas have more in common with the Scotian Shelf and Slope and many common species move seasonally between the Gulf and the open Atlantic Ocean. This report is intended mostly for use by the Canada-Nova Scotia Offshore Petroleum Board (C-NSOPB), and to a lesser degree the Canada-Newfoundland Offshore Petroleum Board. The maps illustrate the known distribution of certain ecosystem components and known harvesting areas. The first part of the report describes the environmental setting of the southern Gulf of St. Lawrence. The report describes commercially important resources such as benthic, pelagic and shellfish species and other minor species, as well as aquaculture leases. It also discuses seals, whales, raptors, shorebirds and coastal waterfowl. The report identifies tourist areas, recreational parks and protected areas. Seasonality and sensitive timing of the resources are also summarized. refs., tabs., figs.

Filamentous fungal population and species diversity from the continental slope of Bay of Bengal, India

Science.gov (United States)

Das, Surajit; Lyla, Parameswari Somasundharan; Khan, Syed Ajmal

2009-03-01

Filamentous fungal diversity from the sediments of the continental slope of Bay of Bengal was studied. Sediment samples were collected during two voyages in 2004 and 2005. Filamentous fungal population from both the cruises showed a range of 5.17-59.51 CFU/g and 3.47-29.68 CFU/g, respectively. Totally 16 fungal genera were recorded from both the cruises. Aspergillus was found to be the dominant genus and the overall percentage occurrence was as follows: Deuteromycotina 74%, Ascomycotina 17%, Basidiomycotina 4% and non-sporulating 5%. Diversity indices were calculated and during both the cruises species richness ( d) varied from 0.912 to 3.622 and 1.443 to 4.588; evenness ( J') varied from 0.9183 to 1.000 and 0.8322 to 1.000 and Shannon-Wiener index ( H' log 2) varied from 0.9183 to 1.000 and 1.000 to 3.690. The higher diversity was found in Divipoint transect (northern Bay of Bengal). 95% confidence interval and ellipse showed that the stations were well lying within the funnel. Cluster analysis and MDS grouped the northern transects which showed higher diversity. BVSTEP resulted in isolation of 23 species which were most influential in the marine filamentous fungal diversity of the continental slope of Bay of Bengal. Thus, a lower population range and higher diversity of marine filamentous marine fungi in the sediments of the continental slope of Bay of Bengal was recorded.

Temporal variability in shell mound formation at Albatross Bay, northern Australia.

Directory of Open Access Journals (Sweden)

Simon J Holdaway

Full Text Available We report the results of 212 radiocarbon determinations from the archaeological excavation of 70 shell mound deposits in the Wathayn region of Albatross Bay, Australia. This is an intensive study of a closely co-located group of mounds within a geographically restricted area in a wider region where many more shell mounds have been reported. Valves from the bivalve Tegillarca granosa (Linnaeus, 1758 were dated. The dates obtained are used to calculate rates of accumulation for the shell mound deposits. These demonstrate highly variable rates of accumulation both within and between mounds. We assess these results in relation to likely mechanisms of shell deposition and show that rates of deposition are affected by time-dependent processes both during the accumulation of shell deposits and during their subsequent deformation. This complicates the interpretation of the rates at which shell mound deposits appear to have accumulated. At Wathayn, there is little temporal or spatial consistency in the rates at which mounds accumulated. Comparisons between the Wathayn results and those obtained from shell deposits elsewhere, both in the wider Albatross Bay region and worldwide, suggest the need for caution when deriving behavioural inferences from shell mound deposition rates, and the need for more comprehensive sampling of individual mounds and groups of mounds.

Assessing Drivers of Coastal Primary Production in Northern Marguerite Bay, Antarctica

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Patrick D. Rozema

2017-06-01

Full Text Available The coastal ocean of the climatically-sensitive west Antarctic Peninsula is experiencing changes in the physical and (photochemical properties that strongly affect the phytoplankton. Consequently, a shift from diatoms, pivotal in the Antarctic food web, to more mobile and smaller flagellates has been observed. We seek to identify the main drivers behind primary production (PP without any assumptions beforehand to obtain the best possible model of PP. We employed a combination of field measurements and modeling to discern and quantify the influences of variability in physical, (photochemical, and biological parameters on PP in northern Marguerite Bay. Field data of high-temporal resolution (November 2013–March 2014 collected at a long-term monitoring site here were combined with estimates of PP derived from photosynthesis-irradiance incubations and modeled using mechanistic and statistical models. Daily PP varied greatly and averaged 1,764 mg C m−2 d−1 with a maximum of 6,908 mg C m−2 d−1 after the melting of sea ice and the likely release of diatoms concentrated therein. A non-assumptive random forest model (RF with all possibly relevant parameters (MRFmax showed that variability in PP was best explained by light availability and chlorophyll a followed by physical (temperature, mixed layer depth, and salinity and chemical (phosphate, total nitrogen, and silicate water column properties. The predictive power from the relative abundances of diatoms, cryptophytes, and haptophytes (as determined by pigment fingerprinting to PP was minimal. However, the variability in PP due to changes in species composition was most likely underestimated due to the contrasting strategies of these phytoplankton groups as we observed significant negative relations between PP and the relative abundance of flagellates groups. Our reduced model (MRFmin showed how light availability, chlorophyll a, and total nitrogen concentrations can be used to obtain the best

Using Coupled Models to Study the Effects of River Discharge on Biogeochemical Cycling and Hypoxia in the Northern Gulf of Mexico

Science.gov (United States)

Penta, Bradley; Ko, D.; Gould, Richard W.; Arnone, Robert A.; Greene, R.; Lehrter, J.; Hagy, James; Schaeffer, B.; Murrell, M.; Kurtz, J.;

New Mediterranean Biodiversity Records (October, 2014

Directory of Open Access Journals (Sweden)

S. KATSANEVAKIS

2014-11-01

Full Text Available The Collective Article ‘New Mediterranean Biodiversity Records’ of the Mediterranean Marine Science journal offers the means to publish biodiversity records in the Mediterranean Sea. The current article is divided in two parts, for records of alien and native species respectively. The new records of alien species include: the red alga Asparagopsis taxiformis (Crete and Lakonicos Gulf (Greece; the red alga Grateloupia turuturu (along the Israeli Mediterranean shore; the mantis shrimp Clorida albolitura (Gulf of Antalya, Turkey; the mud crab Dyspanopeus sayi (Mar Piccolo of Taranto, Ionian Sea; the blue crab Callinectes sapidus (Chios Island, Greece; the isopod Paracerceis sculpta (northern Aegean Sea, Greece; the sea urchin Diadema setosum (Gökova Bay, Turkey; the molluscs Smaragdia souverbiana, Murex forskoehlii, Fusinus verrucosus, Circenita callipyga, and Aplysia dactylomela (Syria; the cephalaspidean mollusc Haminoea cyanomarginata (Baia di Puolo, Massa Lubrense, Campania, southern Italy; the topmouth gudgeon Pseudorasbora parva (Civitavecchia, Tyrrhenian Sea; the fangtooth moray Enchelycore anatine (Plemmirio marine reserve, Sicily; the silver-cheeked toadfish Lagocephalus sceleratus (Saros Bay, Turkey; and Ibiza channel, Spain; the Indo-Pacific ascidian Herdmania momusin Kastelorizo Island (Greece; and the foraminiferal Clavulina multicam erata (Saronikos Gulf, Greece. The record of L. sceleratus in Spain consists the deepest (350-400m depth record of the species in the Mediterranean Sea. The new records of native species include: first record of the ctenophore Cestum veneris in Turkish marine waters; the presence of Holothuria tubulosa and Holothuria polii in the Bay of Igoumenitsa (Greece; the first recorded sighting of the bull ray Pteromylaeus bovinus in Maltese waters; and a new record of the fish Lobotes surinamensis from Maliakos Gulf.

Acquisition of airborne imagery in support of Deepwater Horizon oil spill recovery assessments

Science.gov (United States)

Bostater, Charles R., Jr.; Muller-Karger, Frank E.

2012-09-01

Remote sensing imagery was collected from a low flying aircraft along the near coastal waters of the Florida Panhandle and northern Gulf of Mexico and into Barataria Bay, Louisiana, USA, during March 2011. Imagery was acquired from an aircraft that simultaneously collected traditional photogrammetric film imagery, digital video, digital still images, and digital hyperspectral imagery. The original purpose of the project was to collect airborne imagery to support assessment of weathered oil in littoral areas influenced by the Deepwater Horizon oil and gas spill that occurred during the spring and summer of 2010. This paper describes the data acquired and presents information that demonstrates the utility of small spatial scale imagery to detect the presence of weathered oil along littoral areas in the northern Gulf of Mexico. Flight tracks and examples of imagery collected are presented and methods used to plan and acquire the imagery are described. Results suggest weathered oil in littoral areas after the spill was contained at the source.

Long-Term Water Temperature Variations in Daya Bay, China Using Satellite and In Situ Observations

Directory of Open Access Journals (Sweden)

Jing Yu

2010-01-01

Full Text Available Daya Bay is a shallow, semi-en closed bay in the northern section of the South China Sea. The present study analyzed variations of water temperature in Daya Bay over the past 21 years (1985 - 2005 using Advanced Very High Resolution Radiometer (AVHRR satellite remote sensing data and in situ observations. Results showed that AVHRR readings of sea surface temperature (SST increased by 0.07°C y-1. Linear regression anal y sis for monthly SST anomalies (SSTA showed a shift from negative to positive from 1995 - 1996, when the Daya Bay nuclear power station commenced operations in 1994. The slope of linear regression analysis for SSTA nearly doubled from 0.05 (1985 - 1993 to 0.09 (1994 - 2005. Monthly AVHRR images showed a thermal plume from the power station and revealed the in crease of SST over 21 years. In situ observations in water temperature also showed an in creasing trend for the same period (1985 - 2005. Variations in water temperature in Daya Bay were connected with climatic perturbations and in creasing human activity including thermal discharge from nuclear power stations and the rapid economic development around the bay area.

Feeding by grey seals in the Gulf of St. Lawrence and around Newfoundland

Directory of Open Access Journals (Sweden)

M O Hammill

2007-01-01

Full Text Available Diet composition of grey seals in the Gulf of St. Lawrence (Gulf and around the coast of Newfoundland, Canada, was examined using identification of otoliths recovered from digestive tracts. Prey were recovered from 632 animals. Twenty-nine different prey taxa were identified. Grey seals sampled in the northern Gulf of St. Lawrence fed mainly on capelin, mackerel, wolffish and lumpfish during the spring, but consumed more cod, sandlance and winter flounder during late summer. Overall, the southern Gulf diet was more diverse, with sandlance, Atlantic cod, cunner, white hake and Atlantic herring dominating the diet. Capelin and winter flounder were the dominant prey in grey seals sampled from the east coast of Newfoundland, while Atlantic cod, flatfish and capelin were the most important prey from the south coast. Animals consumed prey with an average length of 20.4 cm (Range 4.2-99.2 cm. Capelin were the shortest prey (Mean = 13.9 cm, SE = 0.08, N = 1126, while wolffish were the longest with the largest fish having an estimated length of 99.2 cm (Mean = 59.4, SE = 2.8, N = 63. In the early 1990s most cod fisheries in Atlantic Canada were closed because of the collapse of the stocks. Since then they have shown limited sign of recovery. Diet samples from the west coast of Newfoundland indicate a decline in the contribution of cod to the diet from the pre-collapse to the postcollapse period, while samples from the southern Gulf indicate little change in the contribution of cod.

Preliminary bathymetry of Blackstone Bay and Neoglacial changes of Blackstone Glaciers, Alaska

Science.gov (United States)

Post, Austin

1980-01-01

Preliminary bathymetry (at 1:20,000 scale) and scientific studies of Blackstone Bay Alaska, by the Research Vessel Growler in 1978 disclose that the head of the bay consists of two basins separated by Willard Island and a submarine ridge. Both basins are closed on the north by terminal-moraine bars where Blackstone Glacier and its tributaries terminated as recently as about A.D. 1350; a carbon-14 date of 580 years before present on Badger Point, and old trees farther up the bay, disclose that the glaciers retreated to two narrow inlets at the head of the bay before 1400. The inlets were still glacier-covered until at least 1909. Glaciers in both inlets have continued to retreat; at present they terminate at the head of tidewater, where they discharge small icebergs. Only relatively thin sediments have accumulated in the eastern basin south of the terminal-moraine bar, and most of the bottom is hard and irregular as disclosed by soundings and profiles. The northern part of Blackstone Bay is very deep; at more than 1,100 feet below sea level a large, level accumulation of sediment is present which is presumably as much as 1,000 feet deep and has been accumulating since late Pleistocene glaciers retreated. (USGS)

On the circulation in the Bay of Bengal during northern spring inter-monsoon (March-April 1987)

Digital Repository Service at National Institute of Oceanography (India)

Babu, M.T.; Sarma, Y.V.B.; Murty, V.S.N.; Vethamony, P.

) indicated an anticyclonic circulation with a northeastward flow in the western bay duringMarch–April ( La Fond and La Fond 1968; Duing, 1970; Wyrtki, 1971). The temperature field obtained from satellite- based advanced very high resolution radiometer (AVHRR.... Pergamon. New York, pp. 451–475. Duing,W.,1970.Themonsoonregimeofcurrentsin theIndian Ocean. University Press of Hawaii, Honolulu, USA, 68pp. Eigenheer,A.,Quadfasel,D.,2000.SeasonalvariabilityoftheBay of Bengal circulation inferred from TOPEX...

Canada’s 2009 Northern Strategy: Cold War Policy in a Warming Arctic

Science.gov (United States)

2011-05-19

more harm than benefit to Northern peoples like the Inuit , the people most directly affected by Arctic activities. They argue there is no immediate...waterways of the Arctic Archipelago, the Canadian government re-settled eight native Inuit families from northern Quebec to Resolute Bay and Grise Ford...76 Initially the re-location was claimed to be a humanitarian effort intended to save the lives of starving Inuit by providing them with new

Dolphins in a Scaled-Down Mediterranean: The Gulf of Corinth's Odontocetes.

Science.gov (United States)

Bearzi, G; Bonizzoni, S; Santostasi, N L; Furey, N B; Eddy, L; Valavanis, V D; Gimenez, O

The Gulf of Corinth is a 2400-km 2 semi-enclosed inland system (a mediterraneus) in central Greece. Its continental shelf areas, steep bottom relief, and waters up to 500-900m deep offer suitable habitat to neritic and pelagic species. We used photographic capture-recapture, distribution modelling, and direct observations to investigate the abundance, status, habitat preferences, movements, and group size of four odontocete species regularly observed in the Gulf, based on five years (2011-2015) of survey effort from small boats. Striped dolphins (Stenella coeruleoalba) are more abundant (1324 individuals, 95%CI 1158-1515) than was determined from previous estimates. Striped dolphins appear to be confined to the Gulf, where they favour deep and oligotrophic waters, and were encountered in single-species and mixed-species groups. Short-beaked common dolphins (Delphinus delphis) (22 individuals, 95%CI 16-31), individuals with intermediate pigmentation (possibly striped/common dolphin hybrids) (55, 95%CI 36-83), and a single Risso's dolphin (Grampus griseus) were only encountered in mixed-species groups with striped dolphins. Short-beaked common dolphins constitute a discrete conservation unit (subpopulation), and based on the current estimate, would qualify as Critically Endangered according to International Union for the Conservation of Nature (IUCN) Red List criteria. Common bottlenose dolphins (Tursiops truncatus) (39 animals, 95%CI 33-47) occur in single-species groups; they prefer continental shelf waters and areas near fish farms in the northern sector, and several animals appear to move into and out of the Gulf. Additionally, we contribute records of marine fauna and an assessment of the fishing fleet operating in the Gulf. Our study shows that the importance of this vulnerable marine environment has been underestimated, and management action must be taken to mitigate human impact and ensure long-term protection. © 2016 Elsevier Ltd All rights reserved.

33 CFR 334.770 - Gulf of Mexico and St. Andrew Sound, south of East Bay, Fla., Tyndall Drone Launch Corridor...

Science.gov (United States)

2010-07-01

... Sound, south of East Bay, Fla., Tyndall Drone Launch Corridor, Tyndall Air Force Base, Fla.; restricted.... Andrew Sound, south of East Bay, Fla., Tyndall Drone Launch Corridor, Tyndall Air Force Base, Fla... referred to as the “Tyndall Drone Launch Corridor.” (b) The regulations. (1) Military usage of areas is...

Pichicuco 7: Gulf of California CTD Data Report: U.S. Research Vessel, R/V New Horizon,

Science.gov (United States)

1985-03-01

de Investigaciones Scientificas y de Educacion Superior de Ensenada, Ensenada, B.C.. Mexico. %i- Table of Contents Abstract...hydrographic characteristics, especially as they might apply to water mass formation processes in the northern Gulf. This report presents individual profiles...investigadores del Cen- Investigaci6n Cientiica y Educaci6n Superior de tro de Investigacidn Cientifica y Educacion Ensenada and Scripps Institution of

A Numerical Study of Hydrodynamics and Sediment Transport in Fourleague Bay, Louisiana

Science.gov (United States)

Hu, K.; Chen, Q. J.; Xu, K.; Bentley, S. J.; WANG, J.

2017-12-01

Fourleague Bay is a shallow and vertically well-mixed estuary in south-central Louisiana. This estuary is highly impacted by wind (e.g., cold fronts and tropical storms), river discharge from the Atchafalaya River and tides from the Gulf of Mexico, and is being used as an analog site to study impacts of sediment-diversion restoration strategies in the Mississippi River Delta. In this study, a coupled flow-wave Delft3D model was setup and applied to study hydrodynamics and sediment transport in this area. The model grid size is 1071x631 with a 50-m resolution in the bay. Vegetation is considered by rigid cylinders in both flow and wave modules. The offshore water level boundary conditions were provided by a Gulf-scale Delft3D model. Model parameters, especially for cohesive sediment transport such as settling velocity, erosion rate and critical bottom shear stress, were calibrated using the field observation data during three seasons from May 2015 to March 2016. The modeled water levels, currents, significant wave heights and suspended sediment concentrations agreed fairly well with measurements, which suggests a reasonable model performance. Seasonal variations were analyzed based on different scenarios. A series of numerical experiments were set up to quantify the contributions of different factors, such as river discharge, tides and waves to sediment transport in this area. This model will be further applied to be part of a landscape ecosystem model to test landscape and population change over time with manipulations to sediment delivery. This study was funded by the National Science Foundation (SEES-1427389 and CCF-1539567).

Stratigraphy and palaeoceanography of a topography-controlled contourite drift in the Pen Duick area, southern Gulf of Cádiz

NARCIS (Netherlands)

Vandorpe, T.; Van Rooij, D.; de Haas, H.

2014-01-01

The northern part of the Gulf of Cádiz has and still is receiving a lot of attention from the scientific community due to (amongst others) the recent IODP Expedition 339. In contrast, its southern part, or the Moroccan margin has received far less attention, although mud volcanoes, diapiric ridges

Molecular and biochemical responses of hypoxia exposure in Atlantic croaker collected from hypoxic regions in the northern Gulf of Mexico.

Science.gov (United States)

Rahman, Md Saydur; Thomas, Peter

2017-01-01

A major impact of global climate change has been the marked increase worldwide in the incidence of coastal hypoxia (dissolved oxygen, DOhypoxic waters as well as their molecular and physiological responses to environmental hypoxia exposure are largely unknown. A suite of potential hypoxia exposure biomarkers was evaluated in Atlantic croaker collected from hypoxic and normoxic regions in the northern Gulf of Mexico (nGOM), and in croaker after laboratory exposure to hypoxia (DO: 1.7 mg l-1). Expression of hypoxia-inducible factor-α, hif-α; neuronal nitric oxide synthase, nNOS; and insulin-like growth factor binding protein, igfbp mRNAs and protein carbonyl (PC, an oxidative stress indicator) content were elevated several-fold in brain and liver tissues of croaker collected from nGOM hypoxic sites. All of these molecular and biochemical biomarkers were also upregulated ~3-10-fold in croaker brain and liver tissues within 1-2 days of hypoxia exposure in controlled laboratory experiments. These results suggest that hif-αs, nNOS and igfbp-1 transcripts and PC contents are useful biomarkers of environmental hypoxia exposure and some of its physiological effects, making them important components for improved assessments of long-term impacts of environmental hypoxia on fish populations.

2015 Gulf Guardian Awards

Science.gov (United States)

The Gulf of Mexico Program Partnership developed the Gulf Guardian awards as a way to recognize and honor the businesses, community groups, individuals, and agencies that are taking positive steps to keep the Gulf healthy, beautiful and productive.

The combined effects of acidification and hypoxia on pH and aragonite saturation in the coastal waters of the California current ecosystem and the northern Gulf of Mexico

Science.gov (United States)

Feely, Richard A.; Okazaki, Remy R.; Cai, Wei-Jun; Bednaršek, Nina; Alin, Simone R.; Byrne, Robert H.; Fassbender, Andrea

2018-01-01

Inorganic carbon chemistry data from the surface and subsurface waters of the West Coast of North America have been compared with similar data from the northern Gulf of Mexico to demonstrate how future changes in CO2 emissions will affect chemical changes in coastal waters affected by respiration-induced hypoxia ([O2] ≤ 60 μmol kg-1). In surface waters, the percentage change in the carbon parameters due to increasing CO2 emissions are very similar for both regions even though the absolute decrease in aragonite saturation is much higher in the warmer waters of the Gulf of Mexico. However, in subsurface waters the changes are enhanced due to differences in the initial oxygen concentration and the changes in the buffer capacity (i.e., increasing Revelle Factor) with increasing respiration from the oxidation of organic matter, with the largest impacts on pH and CO2 partial pressure (pCO2) occurring in the colder West Coast waters. As anthropogenic CO2 concentrations begin to build up in subsurface waters, increased atmospheric CO2 will expose organisms to hypercapnic conditions (pCO2 >1000 μatm) within subsurface depths. Since the maintenance of the extracellular pH appears as the first line of defense against external stresses, many biological response studies have been focused on pCO2-induced hypercapnia. The extent of subsurface exposure will occur sooner and be more widespread in colder waters due to their capacity to hold more dissolved oxygen and the accompanying weaker acid-base buffer capacity. Under present conditions, organisms in the West Coast are exposed to hypercapnic conditions when oxygen concentrations are near 100 μmol kg-1 but will experience hypercapnia at oxygen concentrations of 260 μmol kg-1 by year 2100 under the highest elevated-CO2 conditions. Hypercapnia does not occur at present in the Gulf of Mexico but will occur at oxygen concentrations of 170 μmol kg-1 by the end of the century under similar conditions. The aragonite saturation

Archive of Sidescan Sonar and Swath Bathymetry Data Collected During USGS Cruise 13CCT04 Offshore of Petit Bois Island, Gulf Islands National Seashore, Mississippi, August 2013

Science.gov (United States)

DeWitt, Nancy T.; Flocks, James G.; Kindinger, Jack G.; Bernier, Julie C.; Kelso, Kyle W.; Wiese, Dana S.; Finlayson, David P.; Pfeiffer, William R.

2015-01-01

In August of 2013, the U.S. Geological Survey conducted a geophysical survey offshore of Petit Bois Island, Mississippi. This effort was part of the U.S. Geological Survey Gulf of Mexico Science Coordination partnership with the U.S. Army Corps of Engineers to assist the Mississippi Coastal Improvements Program and the Northern Gulf of Mexico Ecosystem Change and Hazards Susceptibility Project, by mapping the shallow geologic stratigraphic framework of the Mississippi Barrier Island Complex.

Small scale features of sound velocity structure in the northern Arabian sea during February - May 1974

Digital Repository Service at National Institute of Oceanography (India)

Somayajulu, Y.K.; Rao, L.V.G.; Varadachari, V.V.R.

at intermediate depths (200-400 m), influence the sound velocity structure and cause formation of an upper sound channel in the northern Arabian Sea. The Persian Gulf waters spread as tongues at 1 or 2 more levels (up to a limited extent), besides the prominent...

Spatial-temporal distribution of phytoplankton pigments in relation to nutrient status in Jiaozhou Bay, China

Science.gov (United States)

Yao, Peng; Yu, Zhigang; Deng, Chunmei; Liu, Shuxia; Zhen, Yu

2010-10-01

We conducted studies of phytoplankton and hydrological variables in a semi-enclosed bay in northern China to understand the spatial-temporal variability and relationship between these variables. Samples were collected during seven cruises in Jiaozhou Bay from November 2003 to October 2004, and were analyzed for temperature, nutrients and phytoplankton pigments. Pigments from eight possible phytoplankton classes (Diatoms, Dinoflagellates, Chlorophyceae, Prasinophyceae, Chrysophyceae, Haptophyceae, Cryptophyceae and Caynophyceae) were detected in surface water by high performance liquid chromatography (HPLC). Phytoplankton pigment and nutrient concentrations in Jiaozhou Bay were spatially and temporally variable, and most of them were highest in the northern and eastern parts of the sampling regions in spring (May) and summer (August), close to areas of shellfish culturing, river estuaries, dense population and high industrialization, reflecting human activities. Chlorophyll a was recorded in all samples, with an annual mean concentration of 1.892 μg L -1, and fucoxanthin was the most abundant accessory pigment, with a mean concentration of 0.791 μg L -1. The highest concentrations of chlorophyll a (15.299 μg L -1) and fucoxanthin (9.417 μg L -1) were observed in May 2004 at the station close to the Qingdao Xiaogang Ferry, indicating a spring bloom of Diatoms in this area. Although chlorophyll a and other biomarker pigments showed significant correlations, none of them showed strong correlations with temperature and nutrients, suggesting an apparent de-coupling between the pigments and these hydrological variables. The nutrient composition and phytoplankton community composition of Jiaozhou Bay have changed significantly in the past several decades, reflecting the increasing nutrient concentrations and decline of phytoplankton cell abundance. The unchanged total chlorophyll a levels indicated that smaller species have filled the niche vacated by the larger

Gulf of Mexico soundscapes as indicators of ecological stressors

Science.gov (United States)

Sidorovskaia, N.; Li, K.; Tiemann, C.; Ackleh, A. S.; Tang, T.; Risbourg, J. H.

2016-12-01

Soundscapes in the Northern Gulf of Mexico are complex and represent a combination of anthropogenic noise (oil exploration and production, shipping, rig construction, etc.), bio-soundscapes (sound of marine mammals and fish), and geo-soundscapes (weather events, submarine landslides, distant earthquakes, natural gas seeps). We will discuss how Passive Acoustic Monitoring in the deep Gulf has been utilized during the past decade to study the soundscape variability on daily, monthly, and yearly timescales and what environmental information can be extracted from this variability. Isolation of bio-soundscapes, identification of their sources, and abundance estimates based on acoustic cues are used to track the recovery of marine mammal species after major ecological disasters, such as the recent 2010 oil spill. Association of acoustic activity of marine species with anthropogenic noise levels and other environmental variables can provide base data that can be used to build ecological models of habitat preferences for different marine species. Understanding how the variability of anthropogenic soundscapes correlates with marine species distributions is critically important for regional conservation and mitigation strategies. Such studies can also assist in forecasting the long-term ecosystem health status and ecosystem response to disturbances of different spatial and temporal extent, including slow variations associated with climate change. [This research was made possible in part by a grant from The Gulf of Mexico Research Initiative, and in part by funding provided by ONR and The Joint Industry Programme.

Microtremor measurements in the northern coast of˙Izmir Bay ...

Indian Academy of Sciences (India)

be an effective tool for assessment of local soil conditions in case of thick soft sediments in the northern coast of ˙Izmir .... duration of 30 minutes with 100 samples per sec- ond. ..... motions, high level of amplification may take place. Although ...

RB-10-07 Lophelia II 2010: Oil Seeps and Deep Reefs on NOAA Ship Ronald H. Brown in the Gulf of Mexico between 20101014 and 20101104

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Lophelia II project involves exploration and research of the northern Gulf of Mexico deepwater natural and artificial hard bottom habitats with emphasis on coral...

Aerosol pollution over Northern India and Bangladesh

Science.gov (United States)

2002-01-01

The skies over Northern India are filled with a thick soup of aerosol particles all along the southern edge of the Himalayan Mountains, and streaming southward over Bangladesh and the Bay of Bengal. Notice that the air over the Tibetan Plateau to the north of the Himalayas is very clear, whereas the view of the land surface south of the mountains is obstructed by the brownish haze. Most of this air pollution comes from human activities. The aerosol over this region is notoriously rich in sulfates, nitrates, organic and black carbon, and fly ash. These particles not only represent a health hazard to those people living in the region, but scientists have also recently found that they can have a significant impact on the region's hydrological cycle and climate (click to read the relevant NASA press release). This true-color image was acquired on December 4, 2001, by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite. It is interesting to compare the image above with this earlier MODIS image over the region, acquired on October 23, 2001. Notice the difference in the clarity of the air over the region in the earlier image. Under the thick plume of aerosol, the Brahmaputra (upper right) and Ganges Rivers are still visible. The many mouths of the Ganges have turned the northern waters of the Bay of Bengal a murky brown as they empty their sediment-laden waters into the bay. Toward the upper lefthand corner of the image, there appears to be a fresh swath of snow on the ground just south of the Himalayas.

33 CFR 100.124 - Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York. 100.124 Section 100.124 Navigation and Navigable... NAVIGABLE WATERS § 100.124 Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York...

GIS-based health assessment of the marine ecosystem in Laizhou Bay, China.

Science.gov (United States)

Song, Debin; Gao, Zhiqiang; Zhang, Hua; Xu, Fuxiang; Zheng, Xiangyu; Ai, Jinquan; Hu, Xiaoke; Huang, Guopei; Zhang, Haibo

2017-12-15

According to 2014-2016 monitoring data, an assessment index system including water quality, depositional environment and ecosystem was built to evaluate the health statue of marine ecosystem in the Laizhou Bay using analytic hierarchy process (AHP) method. The results, spatialized in ArcGIS software, show: while the comprehensive ecological health index is 0.62, the ecological environmental quality in the Laizhou Bay is in a sub-healthy state; the unhealthy area is mainly concentrated in southwestern inshore region, and impacted by serious environmental problems, such as water eutrophication and heavy metal pollution; the northwestern and southeastern inshore regions are in a sub-healthy state, while the eastern inshore and northern areas are in the healthiest state. The land-based pollutants that discharge into the sea may be the leading factors that are causing ecological environment deterioration in the Laizhou Bay, and the reclamation work ongoing around the port has exacerbated the ecological risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spatial and temporal variability of seawater pCO2 within the Canadian Arctic Archipelago and Baffin Bay during the summer and autumn 2011

DEFF Research Database (Denmark)

Geilfus, N.-X.; Pind, M. L.; Else, B. G. T.

2018-01-01

The partial pressure of CO2 in surface water (pCO2sw) measured within the Canadian Arctic Archipelago (CAA) and Baffin Bay was highly variable with values ranging from strongly undersaturated (118 μatm) to slightly supersaturated (419 μatm) with respect to the atmospheric levels ( 386 μatm) during...... summer and autumn 2011. During summer, melting sea ice contributed to cold and fresh surface water and enhanced the ice-edge bloom, resulting in strong pCO2sw undersaturation. Coronation Gulf was the only area with supersaturated pCO2sw, likely due to warm CO2-enriched freshwater input from...... the Coppermine River. During autumn, the entire CAA (including Coronation Gulf) was undersaturated, despite generally increasing pCO2sw. Coronation Gulf was the one place where pCO2sw decreased, likely due to seasonal reduction in discharge from the Coppermine River and the decreasing sea surface temperature...

Site suitability analysis for Bay scallop aquaculture and implications for sustainable fisheries management in the Ha Long Bay archipelago, northern Vietnam

Directory of Open Access Journals (Sweden)

Pham Thi Khanh

2013-01-01

Full Text Available Mollusc culture if properly managed, may help decrease capture fisheries over-exploitation in Vietnam, and possibly become an alternative income for local fishermen. The definition and characterization of zones suitable for aquaculture is pivotal for its success and sustainable development, and this study aims at determining the suitability of Argopecten irradians (Bay scallop culture in the Ha Long Bay Archipelago. Temperature, salinity, chlorophyll-a, total suspended solid and bathymetry, were compiled in an environmental suitability model. Distance of culture sites from landing points and fish markets were instead grouped in an infrastructural suitability model. In both models, developed with Geographic Information Systems, the suitability scores were ranked on a scale from 1 (unsuitable to 6 (very-highly suitable. Results showed that 98 % of the studied area is environmentally suitable for such culture. However, overlaying the infrastructural factors the suitable zone decrease to 38 %. Advantages and disadvantages of two management options were then discussed: (a strengthening fisheries infrastructures or (b developing post harvesting processing plants.

Cascading of high salinity bottom waters from the Arabian/Persian Gulf to the northern Arabian Sea

Science.gov (United States)

Shapiro, Georgy; Wobus, Fred; Solovyev, Vladimir; Francis, Xavier; Hyder, Patrick; Chen, Feng; Asif, Muhammad

2017-04-01

Cascading (aka shelf convection) is a specific type of buoyancy driven current in which dense water is formed over the continental shelf and then descends down the slope to a greater depth. The cascades of dense water down continental slopes provide a mechanism for shelf-ocean exchange in many parts of the world's oceans (Shapiro et al, 2003). Dense water is formed on the shelf by a number of processes, with high evaporation, limited river discharge and low precipitation being the major processes in warm climates (Ivanov et al, 2004). The formation and outflow of high salinity waters in the near-bottom layer of the Arabian/Persian Gulf is an example of dense water cascading (Bower et al 2000). Despite of its importance for the self-cleaning and the state of the marine ecosystem in the Arabian/Persian Gulf, the properties of the outflow have so far mainly been analysed using climatologically averaged data or observations of a limited set of parameters (mainly temperature), see (Bower et al 2000). In this paper we study the dynamics of the flow using a comprehensive set of observational data (temperature, salinity velocity and turbidity profiles) obtained during the GRASP (Gulf Reconnaissance And Selective Profiling) observational campaign in the Gulf of Oman, which are complemented by the results of numerical modelling of the area using a number of 3D ocean models, and some ARGO T/S profiles. The GRASP measurements were carried out using an Aqualog climbing moored profiler, which was equipped with a Seabird CTD sensor, a Nortek Aquadopp current meter and a Seapoint turbidity meter. The Ocean circulation models used in the study include PGM4 and IND12 (UK Met Office); and AS20 and AG60 (University of Plymouth). All models are based on NEMO (Nucleus for European Modelling of the Ocean) codebase with a resolution from 9 km down to 1.8 km. The models were calibrated and validated against ARGO float profiles in the area. The study revealed the mesoscale and sub

Trace metals in coastal sediments of Costa Rica

International Nuclear Information System (INIS)

Garcia Cespedes, J.; Acuna Gonzalez, J.; Vargas Zamora, J.A.

2004-01-01

Marine sediment samples from four coastal ecosystems in Costa Rica were taken between the years 2000-2002 and their iron, lead, copper and zinc concentrations were determined by the atomic absorption technique with flame or graphite furnace. In the Pacific coast, Culebra Bay (Papagayo Gulf), Gulf of Nicoya, and Golfito Bay (Dulce Gulf), were selected as representative sites, and Moin Bay, at the Caribbean coast. Mean metal concentrations for all ecosystems followed the same pattern: Fe> Zn> Cu> Pb. No temporal pattern was found for any metal. Iron and copper mean concentrations were higher in Golfito Bay (5.8% and 87 μg / g, respectively) and lower in Moin Bay (3.4% and 52 μg / g, respectively). Zinc mean concentration was also higher in Golfito Bay (96 μg / g), but lower in Culebra Bay (66 μg / g). Lead mean concentration was higher in Moin Bay (6.4 μg / g) and lower in Culebra Bay (3.0 μg / g). Lead highest concentrations occurred in the Caribbean and in Golfito Bay, and for the rest of the elements the maximum values were found in Golfito Bay. On the basis of data obtained in this work, Culebra Bay was considered a relatively unpolluted location; Golfito Bay was more contaminated, and Moin Bay and the Gulf of Nicoya showed an intermediate condition. (Author) [es

Seasonal and Interannual Variability of Eddy Field and Surface Circulation in the Gulf of Aden

Science.gov (United States)

Al Saafani, M. A.; Shenoi, S. S. C.

2006-07-01

The circulation in the Gulf of Aden is inferred from three different data sets: h istorical sh ip drifts , hydrography , and satellite altimeter derived sea level (Topex/Poseidon, Jason and ERS) . The circulation in th is semi-enclosed basin is marked with strong seasonality with reversals in the direction of flows twice a year follow ing the reversal in mon soonal winds. During the win ter mon soon (November - February) there is an inflow from Arabian Sea; an extension of Arabian Coastal Current (ACC) . During sou thwest mon soon (June - August) the flow is generally towards east especially along the northern coast of Gulf of Aden. The geostrophic currents also show that the circulation in the gulf is embedded with mesoscale eddies. These westward propagating eddies appear to enter the Gulf of Aden from the western Arabian Sea in win ter. The relative contribu tion of mesoscale eddies to the circulation in the gulf were estimated using altimeter derived Sea level anomaly (SLA) for the years 1993 to 2003 . The effect of these mesoscale eddies extend over the entire water colu mn . The propagation speeds, of these eddies, estimated using weekly spaced altimeter derived SLA (2002 - 2003) is ~ 4 .0 - 5 .3 cm s . The sum of the speeds of second mode Ro ssby wave and the mean current (4.8 cm s ) matches with the propagation speeds of eddies estimated using SLA . Hence, second mode baroclin ic Rossby waves appear to be responsib le for the westward propagation of eddies in the Gulf of Aden. The presence of these eddies in the temperaturesalin ity climato logy confirms that they are no t transient features.

Dissolved oxygen content as an index of water quality in San Vicente Bay, Chile (36 degrees 45'S).

Science.gov (United States)

Rudolph, Anny; Ahumada, Ramón; Pérez, Claudio

2002-08-01

The present report describes some effects of industrial and municipal effluents on the waters of San Vicente Bay. Analyses of the main substances contained in the fishing industry effluent suggest rating criteria based on the oxygen saturation of the water as an assessment of organic pollution. Six cruises were carried out throughout the Bay, from June to December 1996. Water samples were analyzed for dissolved oxygen, oil and grease content, and sediment samples for organic matter content. Water parameters (salinity, temperature) were used to characterize the Bay's hydrography, and to calculate values for oxygen saturation. The measurements demonstrated a local broad range of oxygen deficit, with a maximum of 45% in the winter to 95% in the spring. In November more than 65% of the Bay's area showed oxygen deficits greater than 40%. Organic matter was unusually high in sediments along the northern sector of the Bay. The results suggest that the oxygen depletion was a representative parameter for establishing a relative scale of water quality in this Bay.

Interaction between the tidal and seasonal variability of the Gulf of Maine and Scotian Shelf region

Science.gov (United States)

Katavouta, Anna; Thompson, Keith; Lu, Youyu; Loder, John

2017-04-01

In the Gulf of Maine and Scotian Shelf (off the northeastern coast of North America) tides are large and can alter the local hydrographic properties, circulation, and sea surface height through processes such as tidal rectification, mixing, and horizontal advection. Furthermore, the stratification of the water column can influence tidal elevation and currents over the shelves (e.g., baroclinic tides). To investigate this interaction, a newly developed high resolution (1/36 degree) regional circulation model is used (GoMSS model). First, numerical experiments with and without density stratification are used to demonstrate the influence of stratification on the tides. GoMSS model is then used to interpret the physical mechanisms responsible for the largest seasonal variations in the M2 surface current which occur over, and to the north of, Georges Bank. An alternating pattern of highs and lows in the summer maximum M2 surface speed in the Gulf of Maine is identified, for the first time, in both the model output and observations by a high frequency coastal radar system. This pattern consists of extended striations in tidal speed aligned with the northern flank of Georges Bank that separates the Gulf of Maine from the North Atlantic. The striations are explained in terms of a linear superposition of the barotropic tide flowing across the northern flank of Georges Bank and the reflected, phase-locked baroclinic tide. The striations have amplitudes of about 0.1 m/s and longitudinal length scales of order 100 km, and are thus of practical significance.

Gulf of Mexico: Dealing with Change in a Marginal Sea

Science.gov (United States)

Rabalais, N. N.

2017-12-01

instances around the Gulf margin. Similar areas exist along the northern and southern Gulf, exhibiting similar processes and challenges.

Prevalence, risk factors and molecular evaluation of hepatitis E virus infection among pregnant women resident in the northern shores of Persian Gulf, Iran

Science.gov (United States)

Farshadpour, Fatemeh; Ravanbod, Mohamad Reza; Eghbali, Seyed Sajjad; Taherkhani, Sakineh; Mahdavi, Easa

2018-01-01

Background Although Iran is reported to be an endemic country for hepatitis E virus (HEV), data on the prevalence of HEV infection among pregnant women are scarce and the epidemiology of HEV is unknown in most parts of the country. Therefore, this study was conducted to elucidate the prevalence, risk factors and genotypic pattern of HEV infection among pregnant women resident in the northern shores of Persian Gulf. This is the first report on the epidemiology of HEV infection among pregnant women in this territory. Methods From October 2016 to May 2017, 1331 pregnant women participated in this study. The mean age ± SD of participants was 27.93±5.7 years with a range of 14–45 years. Serum samples of pregnant women were screened for the presence of anti-HEV total antibodies, anti-HEV IgG and anti-HEV IgM using commercially available ELISA kits (DIA.PRO, Milan, Italy). All anti-HEV IgG and anti-HEV IgM positive samples were tested for HEV RNA using two independent reverse transcriptase polymerase chain reaction (RT-PCR) assays, targeting ORF2 and ORF3 of HEV genome. In addition, 92 anti-HEV seronegative samples as well as 50 pooled seronegative samples were evaluated by two independent RT-PCR assays for validation of results. Results Of the 1331 pregnant women, 84 women (6.3%, 95% CI: 5.1%-7.7%) were positive for anti-HEV antibodies, of which 83 women had anti-HEV IgG, and 11 women (0.83%, 95% CI: 0.47%-1.47%) had anti-HEV IgM. The highest rate of HEV seroprevalence was observed among Afghan immigrants (68.0%), uneducated pregnant women (46.51%) and those residents in Bushehr city (8.75%). All anti-HEV IgG and/or IgM positive samples were found to be negative for HEV RNA. In addition, all of the evaluated anti-HEV seronegative samples were negative for HEV RNA. HEV seropositivity among pregnant women was statistically associated with age, ethnicity, place of residence, number of pregnancies, and level of education. So that, low education levels, Afghan, residence

Monitoring the turbidity and surface temperature changes and effects of the 17 August 1999 earthquake in the Izmit Gulf, Turkey by the Landsat TM/ETM data.

Science.gov (United States)

Tüfekçi, Kenan; Akman, A Unal

2005-09-01

The temporal turbidity and surface temperature changes and effects of the 17 August 1999 earthquake in the Izmit Gulf, Turkey have been investigated using Landsat TM/ETM data. The gulf is in the Mediterranean-Black Sea transition climatic zone and is partially surrounded by green vegetation cover and degraded and densely urbanized-industrialized areas. Landsat TM/ETM data acquired in 1990-1999 confirms increase in turbidity. Turbidity is always low in the southern part and high in the northern part of the gulf, because the more urbanized and industrialized areas are located in the northern part. The Landsat-7 ETM data acquired in the same year (1999) shows seasonal changes in turbidity. Moreover, the two high turbidity and surface temperature anomalies, one of which is parallel to the 17 August 1999 earthquake surface rupture (east-west) and the other which is in the northwest-southeast direction were mapped from Landsat-5 TM data acquired the day (18.08.1999) following the earthquake in the east end of the gulf. On the basis of turbidity implying the sea bottom movement, it is possible to state that a second rupture in the northwest and southeast direction could have occurred at the sea bottom during the earthquake. The distribution of the seismicity centers and the orientation of the lineaments in the area support this finding.

Distribution and Dynamic Habitat Use of Young Bull Sharks Carcharhinus leucas in a Highly Stratified Northern Gulf of Mexico Estuary

OpenAIRE

Drymon, J. Marcus; Ajemian, Matthew J.; Powers, Sean P.

2014-01-01

Understanding how animals alter habitat use in response to changing abiotic conditions is important for effective conservation management. For bull sharks (Carcharhinus leucas), habitat use has been widely examined in the eastern and western Gulf of Mexico; however, knowledge of their movements and the factors influencing them is lacking for populations in the more temperate north-central Gulf of Mexico. To examine how changes in hydrographic conditions affected the presence of young bull sha...

Characterizing the parent and alkyl polycyclic aromatic hydrocarbons in the Pearl River Estuary, Daya Bay and northern South China Sea: Influence of riverine input

International Nuclear Information System (INIS)

Yuan, Ke; Wang, Xiaowei; Lin, Li; Zou, Shichun; Li, Yan; Yang, Qingshu; Luan, Tiangang

2015-01-01

Distributions of 31 parent polycyclic aromatic hydrocarbons (PAHs) and 29 alkyl PAHs in surface sediments of the Pearl River Estuary (PRE), Daya Bay (DYB) and northern South China Sea (SCS) were examined to study the influence of riverine input. It was found that the contributions of riverine input to sediment PAHs in PRE was much higher than other areas. However, higher proportion of alkyl PAHs and low molecular weight PAHs in DYB and the northern SCS was observed, indicating their different sources. Nevertheless, the sediment PAHs in PRE were heterogeneous and affected by the hydrodynamic conditions. The high molecular weight PAHs were dominant in PRE and enriched in the depositional area of suspended particular matter (SPM). Moreover, the concentration of PAHs in SPM was similar to those in surface sediments and dominated in water columns. Therefore, SPM played a very important role in transportation and distribution of PAHs in PRE. - Highlights: • EPA 16 PAHs contributed a small amount of total PAHs. • Alkyl PAHs showed different behaviors from parent PAHs. • High weight PAHs preferably indicated riverine input. • PAHs distribution in sediment was related with the suspended particle deposition. - Suspended particular matter played a very important role in distribution of PAHs in tide-dominated estuary and alkyl PAHs showed different behavior from parent PAHs

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the MELVILLE in the Arabian Sea, Bay of Bengal and others from 1972-07-18 to 1978-04-28 (NODC Accession 0117677)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117677 includes chemical, discrete sample, physical and profile data collected from MELVILLE in the Arabian Sea, Bay of Bengal, Bering Sea, Gulf of...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from MELVILLE in the Arabian Sea, Bay of Bengal and others from 1977-12-04 to 1978-04-28 (NCEI Accession 0163183)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0163183 includes chemical, discrete sample, physical and profile data collected from MELVILLE in the Arabian Sea, Bay of Bengal, Gulf of Aden, Indian...

Hurricane shuts down gulf activity

International Nuclear Information System (INIS)

Koen, A.D.

1992-01-01

This paper reports that producers in the Gulf of Mexico and plant operators in South Louisiana last week were checking for damage wrought by Hurricane Andrew. In its wake Andrew left evacuated rigs and platforms in the gulf and shuttered plants across a wide swath of the Gulf Coast. Operations were beginning to return to normal late last week. Not all gulf operators, especially in the central gulf, expected to return to offshore facilities. And even producers able to book helicopters did not expect to be able to fully assess damage to all offshore installations before the weekend. MMS officials in Washington estimated that 37,500 offshore workers were evacuated from 700 oil and gas installations on the gulf's Outer Continental Shelf. Gulf oil and gas wells account for about 800,000 b/d of oil and one fourth of total U.S. gas production. MMS was awaiting an assessment of hurricane damage before estimating how soon and how much gulf oil and gas production would be restored

High abundance of salps in the coastal Gulf of Alaska during 2011: A first record of bloom occurrence for the northern Gulf

Science.gov (United States)

Li, Kaizhi; Doubleday, Ayla J.; Galbraith, Moira D.; Hopcroft, Russell R.

2016-10-01

Atypical high abundances of two salp species occurred in the coastal Gulf of Alaska during 2011. Salpa aspera dominated numerically in aggregate form during spring, and became uncommon during summer, while Cyclosalpa bakeri increased from low during spring to high abundance during summer. Both species were absent, or nearly so, by fall. C. bakeri abundance was positively correlated to surface temperature in spring and summer, and both species abundances were negatively correlated to chlorophyll a. The proportion of aggregate forms of both species was higher than that of solitary forms during spring and summer. The length-frequency of S. aspera aggregate individuals ranged primarily from 10 to 50 mm, and solitary forms reached 130 mm, while C. bakeri aggregates were 10-25 mm, with solitary forms up to 75 mm. Estimated biomass of S. aspera was 0.35±0.64 mg C m-3 in southeastern Alaska during spring then decreased to 0.03±0.12 mg C m-3 during summer. Estimated biomass of C. bakeri was 0.03±0.06 mg C m-3 over the entire sampling domain during spring, then rose to 0.15±0.25 mg C m-3 during summer. The volume of water filtered daily by S. aspera was estimated to be up to 17% of the 200 m water column at some stations during spring, but only up to 3.5% during summer. Substantially higher grazing impact was possible if animals were largely confined to the surface mixed layer (typically 20-30 m thick). The average volume filtrated was higher during spring for S. aspera, but for C. bakeri it was higher during summer. We propose that the combined effect of the northward transport of seed populations, their rapid biomass increase through asexual reproduction, and the high clearance rate of salps contributed to atypically low chlorophyll a in the Gulf of Alaska during spring and summer of 2011. This unusual event impacted ecosystem function during 2011, and might be expected to increase in frequency as the Gulf continues to respond to climate variations.

Sustainable development in the Hudson Bay/James Bay bioregion

International Nuclear Information System (INIS)

Anon.

1991-01-01

An overview is presented of projects planned for the James Bay/Hudson Bay region, and the expected environmental impacts of these projects. The watershed of James Bay and Hudson Bay covers well over one third of Canada, from southern Alberta to central Ontario to Baffin Island, as well as parts of north Dakota and Minnesota in the U.S.A. Hydroelectric power developments that change the timing and rate of flow of fresh water may cause changes in the nature and duration of ice cover, habitats of marine mammals, fish and migratory birds, currents into and out of Hudson Bay/James Bay, seasonal and annual loads of sediments and nutrients to marine ecosystems, and anadromous fish populations. Hydroelectric projects are proposed for the region by Quebec, Ontario and Manitoba. In January 1992, the Canadian Arctic Resources Committee (CARC), the Environmental Committee of Sanikuluaq, and the Rawson Academy of Arctic Science will launch the Hudson Bay/James Bay Bioregion Program, an independent initiative to apply an ecosystem approach to the region. Two main objectives are to provide a comprehensive assessment of the cumulative impacts of human activities on the marine and freshwater ecosystems of the Hudson Bay/James Bay bioregion, and to foster sustainable development by examining and proposing cooperative processes for decision making among governments, developers, aboriginal peoples and other stakeholders. 1 fig

Rays in the northern Gulf of Mexico: Aerial Survey and Satellite Telemetry 2008-2012 (NCEI Accession 0129495)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The dataset contains distribution and abundance data for rays in the Gulf of Mexico collected through aerial surveys and satellite telemetry. Aerial survey data...

Three decadal inputs of total organic carbon from four major coastal river basins to the summer hypoxic zone of the Northern Gulf of Mexico.

Science.gov (United States)

He, Songjie; Xu, Y Jun

2015-01-15

This study investigated long-term (1980-2009) yields and variability of total organic carbon (TOC) from four major coastal rivers in Louisiana entering the Northern Gulf of Mexico where a large-area summer hypoxic zone has been occurring since the middle 1980s. Two of these rivers drain agriculture-intensive (>40%) watersheds, while the other two rivers drain forest-pasture dominated (>50%) watersheds. The study found that these rivers discharged a total of 13.0×10(4)t TOC annually, fluctuating from 5.9×10(4) to 22.8×10(4)t. Seasonally, the rivers showed high TOC yield during the winter and early spring months, corresponding to the seasonal trend of river discharge. While river hydrology controlled TOC yields, land use has played an important role in fluxes, seasonal variations, and characteristics of TOC. The findings fill in a critical information gap of quantity and quality of organic carbon transport from coastal watersheds to one of the world's largest summer hypoxic zones. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

Kishinhi, Stephen S; Tchounwou, Paul B; Farah, Ibrahim O

2013-01-01

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

Mycobacterial infection in Northern snakehead (Channa argus) from the Potomac River catchment

Science.gov (United States)

Densmore, Christine L.; Iwanowicz, L.R.; Henderson, A.P.; Iwanowicz, D.D.; Odenkirk, J.S.

2016-01-01

The Northern snakehead, Channa argus (Cantor), is a non-native predatory fish that has become established regionally in some temperate freshwater habitats within the United States. Over the past decade, Northern snakehead populations have developed within aquatic ecosystems throughout the eastern USA, including the Potomac River system within Virginia, Maryland and Washington, D.C. Since this species was initially observed in this region in 2002, the population has expanded considerably (Odenkirk & Owens 2007). In the Chesapeake Bay watershed, populations of Northern snakehead exist in the lower Potomac River and Rappahannock Rivers on the Western shore of the Bay, and these fish have also been found in middle or upper reaches of river systems on the Eastern shore of the Bay, including the Nanticoke and Wicomico Rivers among others. Over the past several years, many aspects of Northern snakehead life history in the Potomac River have been described, including range and dispersal patterns, microhabitat selection and diet (Lapointe, Thorson & Angermeier 2010; Saylor, Lapointe & Angermeier 2012; Lapointe, Odenkirk & Angermeier 2013). However, comparatively little is known about their health status including susceptibility to parasitism and disease and their capacity to serve as reservoirs of disease for native wildlife. Although considered hardy by fisheries biologists, snakehead fish have demonstrated susceptibility to a number of described piscine diseases within their native range and habitat in Asia. Reported pathogens of significance in snakehead species in Asia include snakehead rhabdovirus (Lio-Po et al. 2000), aeromonad bacteria (Zheng, Cao & Yang 2012), Nocardia (Wang et al. 2007) andMycobacterium spp. (Chinabut, Limsuwan & Chantatchakool 1990; ). Mycobacterial isolates recovered from another snakehead species (Channa striata) in the previous studies have included M. marinum and M. fortuitum, as identified through molecular

76 FR 54375 - Safety Zone; Thunder on the Gulf, Gulf of Mexico, Orange Beach, AL

Science.gov (United States)

2011-09-01

...-AA00 Safety Zone; Thunder on the Gulf, Gulf of Mexico, Orange Beach, AL AGENCY: Coast Guard, DHS... portion of the Gulf of Mexico for the waters off Orange Beach, Alabama. This action is necessary for the... conduct a high speed boat race on the Gulf of Mexico, south of Orange Beach, Alabama to occur from October...

Movements and habitat use locations of manatees within Kings Bay Florida during the Crystal River National Wildlife Refuge winter season (November 15–March 31)

Science.gov (United States)

Slone, Daniel H.; Butler, Susan M.; Reid, James P.

2018-04-06

Kings Bay, Florida, is one of the most important natural winter habitat locations for the federally threatened Trichechus manatus latirostris (Florida manatee). Crystal River National Wildlife Refuge was established in 1983 specifically to provide protection for manatees and their critical habitat. To aid managers at the refuge and other agencies with this task, spatial analyses of local habitat use locations and travel corridors of manatees in Kings Bay during manatee season (November 15–March 31) are presented based on Global Positioning System telemetry of 41 manatees over a 12-year timespan (2006−18). Local habitat use areas and travel corridors differed spatially when Gulf of Mexico water temperatures were cold (less than or equal to 17 degrees Celsius) versus when they were warm (greater than 17 degrees Celsius). During times of cold water, manatees were found in higher concentrations in the main springs and canals throughout the eastern side of the bay, whereas when waters were warm, they were found more generally throughout the bay and into Crystal River, except for the central open part of the bay and the southwest corner.

Distribution and behavior of major and trace elements in Tokyo Bay, Mutsu Bay and Funka Bay marine sediments

International Nuclear Information System (INIS)

Honda, Teruyuki; Kimura, Ken-ichiro

2003-01-01

Fourteen major and trace elements in marine sediment core samples collected from the coasts along eastern Japan, i.e. Tokyo Bay (II) (the recess), Tokyo Bay (IV) (the mouth), Mutsu Bay and Funka Bay and the Northwest Pacific basin as a comparative subject were determined by the instrumental neutron activation analysis (INAA). The sedimentation rates and sedimentary ages were calculated for the coastal sediment cores by the 210 Pb method. The results obtained in this study are summarized as follows: (1) Lanthanoid abundance patterns suggested that the major origin of the sediments was terrigenous material. La*/Lu* and Ce*/La* ratios revealed that the sediments from Tokyo Bay (II) and Mutsu Bay more directly reflected the contribution from river than those of other regions. In addition, the Th/Sc ratio indicated that the coastal sediments mainly originated in the materials from the volcanic island-arcs, Japanese islands, whereas those from the Northwest Pacific mainly from the continent. (2) The correlation between the Ce/U and Th/U ratios with high correlation coefficients of 0.920 to 0.991 indicated that all the sediments from Tokyo Bay (II) and Funka Bay were in reducing conditions while at least the upper sediments from Tokyo Bay (IV) and Mutsu Bay were in oxidizing conditions. (3) It became quite obvious that the sedimentation mechanism and the sedimentation environment at Tokyo Bay (II) was different from those at Tokyo Bay (IV), since the sedimentation rate at Tokyo Bay (II) was approximately twice as large as that at Tokyo Bay (IV). The sedimentary age of the 5th layer (8∼10 cm in depth) from Funka Bay was calculated at approximately 1940∼50, which agreed with the time, 1943∼45 when Showa-shinzan was formed by the eruption of the Usu volcano. (author)

WATER TEMPERATURE, Depth, and SALINITY collected from RV Walton Smith in Gulf of Mexico from 2012-07-01 to 2012-08-01 (NCEI Accession 0156594)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — 59 CTD casts made from small boats launched by the RV Walton Smith in the northern Gulf of Mexico near DeSoto Canyon in July 2012 as part of the Grand Lagrangian...

Water Temperature, Conductivity, and others collected from RV Walton Smith in Gulf of Mexico from 2012-07-21 to 2012-08-01 (NCEI Accession 0156586)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains 43 CTD casts made from the RV Walton Smith in the northern Gulf of Mexico near DeSoto Canyon in July-August 2012 as part of the Grand...

CONDUCTIVITY, WATER TEMPERATURE, and others collected from R/V Weatherbird II in Gulf of Mexico from 2013-06-24 to 2013-06-30 (NCEI Accession 0156593)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset reports conductivity, temperature and depth data collected in the Northern Gulf of Mexico during the R/V Weatherbird II cruise WB-1318 from June 24-30th...

Oxygenation variability in Mejillones Bay, off northern Chile, during the last two centuries

Science.gov (United States)

Díaz-Ochoa, J. A.; Pantoja, S.; de Lange, G. J.; Lange, C. B.; Sánchez, G. E.; Acuña, V. R.; Muñoz, P.; Vargas, G.

2011-01-01

The Peru Chile Current ecosystem is characterized by high biological productivity and important fisheries. Although this system is likely to be severely affected by climate change, its response to current global warming is still uncertain. In this paper, we analyze 10-166 year-old sediments in two cores collected from Mejillones Bay, an anoxic sedimentary setting favorable for the preservation of proxies. Based on a 166-year chronology, we used proxies of bottom-water oxygenation (Mo, V, S, and the (lycopane + n-C35)/n-C31 ratio) and surface water productivity (biogenic opal, counts of diatom valves, biogenic Ba, organic carbon, and chlorins) to reconstruct environmental variations in Mejillones Bay. During the last two centuries, a shift took place in the coastal marine ecosystem of Bahia Mejillones at decadal scales. This shift was characterized by intense ENSO-like activity, large-scale fluctuations in biological export productivity and bottom water oxygenation, and increased eolian activity (inferred from Ti/Al and Zr/Al). This short-term variability was accompanied by a gradual increase of sulfidic conditions that has intensified since the early 1960s.

Geology and structure of the North Boqueron Bay-Punta Montalva Fault System

Science.gov (United States)

Roig Silva, Coral Marie

The North Boqueron Bay-Punta Montalva Fault Zone is an active fault system that cuts across the Lajas Valley in southwestern Puerto Rico. The fault zone has been recognized and mapped based upon detailed analysis of geophysical data, satellite images and field mapping. The fault zone consists of a series of Cretaceous bedrock faults that reactivated and deformed Miocene limestone and Quaternary alluvial fan sediments. The fault zone is seismically active (ML < 5.0) with numerous locally felt earthquakes. Focal mechanism solutions and structural field data suggest strain partitioning with predominantly east-west left-lateral displacements with small normal faults oriented mostly toward the northeast. Evidence for recent displacement consists of fractures and small normal faults oriented mostly northeast found in intermittent streams that cut through the Quaternary alluvial fan deposits along the southern margin of the Lajas Valley, Areas of preferred erosion, within the alluvial fan, trend toward the west-northwest parallel to the on-land projection of the North Boqueron Bay Fault. Beyond the faulted alluvial fan and southeast of the Lajas Valley, the Northern Boqueron Bay Fault joins with the Punta Montalva Fault. The Punta Montalva Fault is defined by a strong topographic WNW lineament along which stream channels are displaced left laterally 200 meters and Miocene strata are steeply tilted to the south. Along the western end of the fault zone in northern Boqueron Bay, the older strata are only tilted 3° south and are covered by flat lying Holocene sediments. Focal mechanisms solutions along the western end suggest NW-SE shortening, which is inconsistent with left lateral strain partitioning along the fault zone. The limited deformation of older strata and inconsistent strain partitioning may be explained by a westerly propagation of the fault system from the southwest end. The limited geomorphic structural expression along the North Boqueron Bay Fault segment

A Stratigraphic Pollen Record from a Late Pleistocene Cypress Forest, Northern Gulf of Mexico Continental Shelf

Science.gov (United States)

Reese, A.; Harley, G. L.; DeLong, K. L.; Bentley, S. J.; Xu, K.; Gonzalez Rodriguez, S. M.; Truong, J. T.; Obelcz, J.; Caporaso, A.

2017-12-01

Stratigraphic pollen analysis was performed on a layer of preserved peat found near the bottom of a 4.75m vibracore taken in 18m of water off the coast of Orange Beach, Alabama. The core was taken from a site where the remains of a previously buried bald cypress (Taxodium distichum) forest was discovered after wave action, likely from Hurricane Ivan in 2004, scoured and removed the overlying Holocene/late Pleistocene sand sheet. Many of the cypress stumps found at the site are still in growth position, and rooted in the preserved terrestrial soils below. Radiocarbon dating of the peat recovered in core DF1 suggests that the sediment is likely Marine Isotope Stage 3 (MIS 3), or earlier. We hypothesize that the site was quickly buried and preserved by floodplain aggradation associated with sea-level rise that occurred near the end of MIS 3. This rare find provides an opportunity to study in situ fossil pollen from a glacial refugium in the Northern Gulf of Mexico. Pollen results from the lowermost sections within the peat layer show an assemblage consistent with a bald cypress/tupelo gum (Nyssa aquatica) backwater. This is eventually replaced by a more open, possibly brackish, environment, dominated by grasses (Poaceae) and sedges (Cyperaceae). During this change however, there is a brief but very interesting period where the pollen assemblage is likely analogous to the modern day Atlantic Coastal Plain Blackwater Levee/Bar Forests of North and South Carolina. In this modern assemblage, as well as the core samples, birch (Betula), oak (Quercus) and bald cypress are the dominant taxa, along with a strong presence of alder (Alnus), grasses and sedges. We hypothesize that these bar forests formed on areas of higher ground, which resulted from floodplain aggradation that accompanied sea level rise at the end of MIS 3.

Dynamics of photosynthetic photon flux density (PPFD) and estimates in coastal northern California

Science.gov (United States)