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Sample records for africa northeastern atlantic

  1. Atlantic marginal basins of Africa

    SciTech Connect

    Moore, G.T.

    1988-02-01

    The over 10,000-km long Atlantic margin of Africa is divisible into thirty basins or segments of the margin that collectively contain over 18.6 x 10/sup 6/ km/sup 3/ of syn-breakup and post-breakup sediments. Twenty of these basins contain a sufficiently thick volume of sediments to be considered prospects. These basins lie, at least partially, within the 200 m isobath. The distribution of source rocks is broad enough to give potential to each of these basins. The sedimentation patterns, tectonics, and timing of events differ from basin to basin and are related directly to the margin's complex history. Two spreading modes exist: rift and transform. Rifting dates from Late Triassic-Early Jurassic in the northwest to Early Cretaceous south of the Niger Delta. A complex transform fault system separated these two margins. Deep-water communication between the two basins became established in the middle Cretaceous. This Mesozoic-Cenozoic cycle of rifting and seafloor spreading has segmented the margin and where observable, basins tend to be bounded by these segments.

  2. 77 FR 65498 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Adjustment to the Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-29

    ... (75 FR 48874, August 12, 2010). Due to an over-harvest in Area 1A in 2010, the FY 2012 sub-ACL in Area 1A was revised to 24,668 mt on February 24, 2012 (77 FR 10978, February 24, 2012). An additional 295... Northeastern United States; Atlantic Herring Fishery; Adjustment to the Atlantic Herring Management Area 1A...

  3. Atlantic and indian oceans pollution in africa

    NASA Astrophysics Data System (ADS)

    Abubakar, Babagana

    Africa is the second largest and most populated continent after Asia. Geographically it is located between the Atlantic and Indian Oceans. Most of the Africa's most populated and industrialized cities are located along the coast of the continent facing the Atlantic and Indian Oceans, example of such cities include Casablanca, Dakar, Accra, Lagos, Luanda and Cape town all facing the Atlantic Ocean and cities like East London, Durban, Maputo, Dar-es-salaam and Mogadishu are all facing the Indian Ocean. As a result of the geographical locations of African Coastal Cities plus increase in their population, industries, sea port operations, petroleum exploration activities, trafficking of toxic wastes and improper waste management culture lead to the incessant increase in the pollution of the two oceans. NATURE OF POLLUTION OF THE ATLANTIC OCEAN i. The petroleum exploration activities going on along the coast of "Gulf of Guinea" region and Angola continuously causes oil spillages in the process of drilling, bunkering and discharging of petroleum products in the Atlantic Ocean. ii. The incessant degreasing of the Sea Ports "Quay Aprons" along the Coastal cities of Lagos, Luanda, Cape Town etc are continuously polluting the Atlantic Ocean with chemicals. iii. Local wastes generated from the houses located in the coastal cities are always finding their ways into the Atlantic Ocean. NATURE OF POLLUTION OF THE INDIAN OCEAN i. Unlike the Atlantic ocean where petroleum is the major pollutant, the Indian Ocean is polluted by Toxic / Radioactive waste suspected to have been coming from the developed nations as reported by the United Nations Environmental Programme after the Tsunami disaster in December 2004 especially along the coast of Somalia. ii. The degreasing of the Quay Aprons at Port Elizabeth, Maputo, Dar-es-Salaam and Mongolism Sea Ports are also another major source polluting the Indian Ocean. PROBLEMS GENERATED AS A RESULT OF THE OCEANS POLLUTION i. Recent report

  4. Atlantic and Indian Oceans Pollution in Africa

    NASA Astrophysics Data System (ADS)

    Abubakar, B.

    2007-05-01

    Africa is the second largest and most populated continent after Asia. Geographically it is located between the Atlantic and Indian Oceans. Most of the Africa's most populated and industrialized cities are located along the coast of the continent facing the Atlantic and Indian Oceans, example of such cities include Casablanca, Dakar, Accra, Lagos, Luanda and Cape town all facing the Atlantic Ocean and cities like East London, Durban, Maputo, Dar-es-salaam and Mogadishu are all facing the Indian Ocean. As a result of the geographical locations of African Coastal Cities plus increase in their population, industries, sea port operations, petroleum exploration activities, trafficking of toxic wastes and improper waste management culture lead to the incessant increase in the pollution of the two oceans. NATURE OF POLLUTION OF THE ATLANTIC OCEAN i. The petroleum exploration activities going on along the coast of "Gulf of Guinea" region and Angola continuously causes oil spillages in the process of drilling, bunkering and discharging of petroleum products in the Atlantic Ocean. ii. The incessant degreasing of the Sea Ports "Quay Aprons" along the Coastal cities of Lagos, Luanda, Cape Town etc are continuously polluting the Atlantic Ocean with chemicals. iii. Local wastes generated from the houses located in the coastal cities are always finding their ways into the Atlantic Ocean. NATURE OF POLLUTION OF THE INDIAN OCEAN i. Unlike the Atlantic ocean where petroleum is the major pollutant, the Indian Ocean is polluted by Toxic / Radioactive waste suspected to have been coming from the developed nations as reported by the United Nations Environmental Programme after the Tsunami disaster in December 2004 especially along the coast of Somalia. ii. The degreasing of the Quay Aprons at Port Elizabeth, Maputo, Dar-es-Salaam and Mongolism Sea Ports are also another major source polluting the Indian Ocean. PROBLEMS GENERATED AS A RESULT OF THE OCEANS POLLUTION i. Recent report

  5. Atlantic and indian oceans pollution in africa

    NASA Astrophysics Data System (ADS)

    Abubakar, Babagana

    Africa is the second largest and most populated continent after Asia. Geographically it is located between the Atlantic and Indian Oceans. Most of the Africa's most populated and industrialized cities are located along the coast of the continent facing the Atlantic and Indian Oceans, example of such cities include Casablanca, Dakar, Accra, Lagos, Luanda and Cape town all facing the Atlantic Ocean and cities like East London, Durban, Maputo, Dar-es-salaam and Mogadishu are all facing the Indian Ocean. As a result of the geographical locations of African Coastal Cities plus increase in their population, industries, sea port operations, petroleum exploration activities, trafficking of toxic wastes and improper waste management culture lead to the incessant increase in the pollution of the two oceans. NATURE OF POLLUTION OF THE ATLANTIC OCEAN i. The petroleum exploration activities going on along the coast of "Gulf of Guinea" region and Angola continuously causes oil spillages in the process of drilling, bunkering and discharging of petroleum products in the Atlantic Ocean. ii. The incessant degreasing of the Sea Ports "Quay Aprons" along the Coastal cities of Lagos, Luanda, Cape Town etc are continuously polluting the Atlantic Ocean with chemicals. iii. Local wastes generated from the houses located in the coastal cities are always finding their ways into the Atlantic Ocean. NATURE OF POLLUTION OF THE INDIAN OCEAN i. Unlike the Atlantic ocean where petroleum is the major pollutant, the Indian Ocean is polluted by Toxic / Radioactive waste suspected to have been coming from the developed nations as reported by the United Nations Environmental Programme after the Tsunami disaster in December 2004 especially along the coast of Somalia. ii. The degreasing of the Quay Aprons at Port Elizabeth, Maputo, Dar-es-Salaam and Mongolism Sea Ports are also another major source polluting the Indian Ocean. PROBLEMS GENERATED AS A RESULT OF THE OCEANS POLLUTION i. Recent report

  6. Biogeographical Patterns of Marine Benthic Invertebrates Along the Atlantic Coast of the Northeastern USA

    EPA Science Inventory

    Aim Examine the biogeography of marine benthic invertebrates of the Atlantic coast of the northeastern USA, compare the results to historical biogeographic studies, define physical-chemical factors affecting species distributions, and provide biogeographic information needed to ...

  7. 75 FR 20550 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Specifications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... National Oceanic and Atmospheric Administration 50 CFR Part 648 RIN 0648-AY14 Fisheries of the Northeastern United States; Atlantic Herring Fishery; Specifications AGENCY: National Marine Fisheries Service (NMFS... comments. SUMMARY: NMFS proposes 2010-2012 specifications for the Atlantic herring (herring) fishery....

  8. 76 FR 68657 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Temporary Removal of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... 38,146 mt, and 0 mt of the sub-ACL is set aside for research (75 FR 48874, August 12, 2010). Section... Northeastern United States; Atlantic Herring Fishery; Temporary Removal of Herring Trip Limit in Atlantic Herring Management Area 3 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic...

  9. Influence of Surface Processes over Africa on the Atlantic Marine ITCZ and South American Precipitation.

    NASA Astrophysics Data System (ADS)

    Hagos, Samson M.; Cook, Kerry H.

    2005-12-01

    Previous studies show that the climatological precipitation over South America, particularly the Nordeste region, is influenced by the presence of the African continent. Here the influence of African topography and surface wetness on the Atlantic marine ITCZ (AMI) and South American precipitation are investigated.Cross-equatorial flow over the Atlantic Ocean introduced by north south asymmetry in surface conditions over Africa shifts the AMI in the direction of the flow. African topography, for example, introduces an anomalous high over the southern Atlantic Ocean and a low to the north. This results in a northward migration of the AMI and dry conditions over the Nordeste region.The implications of this process on variability are then studied by analyzing the response of the AMI to soil moisture anomalies over tropical Africa. Northerly flow induced by equatorially asymmetric perturbations in soil moisture over northern tropical Africa shifts the AMI southward, increasing the climatological precipitation over northeastern South America. Flow associated with an equatorially symmetric perturbation in soil moisture, however, has a very weak cross-equatorial component and very weak influence on the AMI and South American precipitation. The sensitivity of the AMI to soil moisture perturbations over certain regions of Africa can possibly improve the skill of prediction.

  10. 77 FR 40527 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-10

    ... percent of the quota (8,888 mt) (77 FR 16472, March 21, 2012). Due to an underharvest of quota in... Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Closure of the 2012 Trimester 2 Directed Longfin Squid Fishery AGENCY: National Marine Fisheries Service (NMFS), National Oceanic...

  11. 76 FR 51272 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-18

    ... Loligo was set at 3,384 mt (76 FR 8306, February 14, 2011). Due to an under harvest of the Trimester 1... Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Closure of the 2011 Trimester 2 Directed Loligo Squid Fishery AGENCY: National Marine Fisheries Service (NMFS), National Oceanic...

  12. 77 FR 22678 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-17

    ... percent of the quota (8,888 mt) (77 FR 16472, March 21, 2012). The regulations also require the... National Oceanic and Atmospheric Administration 50 CFR Part 648 RIN 0648- XB145 Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Closure of the Trimester...

  13. 75 FR 48874 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Specifications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-12

    ... on April 20, 2010 (75 FR 20550), with public comment accepted through May 20, 2010. These final... National Oceanic and Atmospheric Administration 50 CFR Part 648 RIN 0648-AY14 Fisheries of the Northeastern United States; Atlantic Herring Fishery; Specifications AGENCY: National Marine Fisheries Service...

  14. 76 FR 39313 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-06

    ... butterfish is 495 mt (76 FR 8306, February 14, 2011). Section 648.22 requires NMFS to close the directed... National Oceanic and Atmospheric Administration 50 CFR Part 648 RIN 0648-XA523 Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Closure of the...

  15. 78 FR 62471 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Framework Adjustment 2 and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 648 RIN 0648-BD17 Fisheries of the Northeastern United States; Atlantic Herring Fishery; Framework Adjustment 2 and Specifications Correction In...

  16. 76 FR 61061 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-03

    ... is 38,146 mt and 0 mt of the sub-ACL is set aside for research (75 FR 48874, August 12, 2010). The... Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch Limit) Harvested for Management... 2,000 lb (907.2 kg) of Atlantic herring (herring) in or from Management Area 3 (Area 3) per...

  17. 75 FR 69903 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Temporary Removal of 2,000...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-16

    ... herring specifications for 2010-2012 published on August 12, 2010 (75 FR 48874). The 2010 total TAC is 91... Northeastern United States; Atlantic Herring Fishery; Temporary Removal of 2,000-lb (907.2 kg) Herring Trip Limit in Atlantic Herring Management Area 1A AGENCY: National Marine Fisheries Service (NMFS),...

  18. 77 FR 10977 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-Annual Catch Limit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-24

    ... specifications (75 FR 48874, August 12, 2010). However, due to an over- harvest in Area 1B in 2010, the FY 2012... Northeastern United States; Atlantic Herring Fishery; Sub-Annual Catch Limit (ACL) Harvested for Management... than 2,000 lb (907.2 kg) of Atlantic herring in or from Management Area 1B per calendar day...

  19. 78 FR 63406 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-Annual Catch Limit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-24

    ... (October 4, 2013, 78 FR 61828). The regulations at Sec. 648.201 require that when the Administrator... Northeastern United States; Atlantic Herring Fishery; Sub-Annual Catch Limit (ACL) Harvested for Management...) of Atlantic herring (herring) per trip or calendar day in or from Management Area 3 until January...

  20. 76 FR 61059 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-03

    ...,362 mt and 0 mt of the sub-ACL is set aside for research (75 FR 48874, August 12, 2010). The... Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch Limit) Harvested for Management... 2,000 lb (907.2 kg) of Atlantic herring (herring) in or from Management Area 1B (Area 1B)...

  1. 75 FR 10450 - Fisheries of the Northeastern United States; Atlantic Bluefish Fisheries; 2010 Atlantic Bluefish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-08

    ...NMFS proposes specifications for the 2010 Atlantic bluefish fishery, including State-by-State commercial quotas, a recreational harvest limit, and recreational possession limits for Atlantic bluefish off the east coast of the United States. The intent of these specifications is to establish the allowable 2010 harvest levels and possession limits to attain the target fishing mortality rate (F),......

  2. Spigelia genuflexa (Loganiaceae), a new geocarpic species from the Atlantic forest of northeastern Bahia, Brazil

    PubMed Central

    Popovkin, Alex V.; Mathews, Katherine G.; Santos, José Carlos Mendes; Molina, M. Carmen; Struwe, Lena

    2011-01-01

    Abstract A new species of Spigelia L. (Loganiaceae), Spigelia genuflexa Popovkin & Struwe, sp. n., from the Atlantic forest of northeastern Bahia, Brazil, is described, being the first reported geocarpic species in the family. During fruit maturation, the basal infructescences bend down towards the ground, depositing the fruit on the surface (and burying it in soft kinds of ground cover, e.g., moss), whereas the upper ones do so slightly but noticeably. The species is a short-lived annual apparently restricted to sandy-soil habitat of the Atlantic forest of northeastern Bahia, with variable and heterogeneous microenvironment and is known from only two restricted localities. A short review of amphi- and geocarpic species is provided. A discussion of comparative morphology within Spigelia with regards to dwarfism, indumentum, and annual habit is included. A phylogenetic parsimony and Bayesian analysis of ITS sequences from 15 Spigelia species plus 17 outgroups in Loganiaceae confirms its independent taxonomic status: on the basis of sequence similarity and phylogenetic topology it is phylogenetically distinct from all Spigelia species sequenced so far. PMID:22287919

  3. Influence of Neoproterozoic tectonic fabric on the origin of the Potiguar Basin, northeastern Brazil and its links with West Africa based on gravity and magnetic data

    NASA Astrophysics Data System (ADS)

    de Castro, David Lopes; Bezerra, Francisco H. R.; Sousa, Maria O. L.; Fuck, Reinhardt A.

    2012-03-01

    The Potiguar Basin is a ˜6,000 m thick aborted NE-trending rift that was formed during the Cretaceous in the continental margin of northeastern Brazil. Its ˜E-W-trending offshore faults form part of the successful continental margin rift that evolved into the South Atlantic Ocean. The region represents one of the most significant pre-Pangea breakup piercing points between eastern South America and West Africa. We used gravity, aeromagnetic, and geological data to assess the role of reactivated Precambrian shear zones and major terrain boundaries in the development of the Potiguar Basin from the Cretaceous to the Cenozoic. We also looked for possible links between these structures in northeastern Brazil and their continuation in West Africa. Our results indicate that the major fault systems of the Potiguar Basin were superimposed on the Precambrian fabric. Both gravity and magnetic maps show lineaments related to the shear zones and major terrain boundaries in the Precambrian crystalline basement, which also characterize the architecture of the rift. For example, the Carnaubais fault, the master fault of the rift system, represents the reactivation of the Portalegre shear zone, the major tectonic boundary between Precambrian terrains in the crystalline basement. In addition, part of the Moho topography is controlled by these shear zones and developed during the period of main rift extension in the Neocomian. The shear zones bounding the Potiguar rift system continue in West Africa around and underneath the Benue Basin, where fault reactivation also took place.

  4. 76 FR 17789 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2011 Atlantic Bluefish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-31

    ... Register on January 14, 2011 (76 FR 2640), with a 15-day comment period which ended on January 31, 2011...), the NMFS Assistant Administrator has determined that this final rule is consistent with the Atlantic... Assistant Administrator for Regulatory Programs, National Marine Fisheries Service. For the reasons set...

  5. 77 FR 10668 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ... 22,146 mt, and 0 mt of the sub-ACL is set aside for research (75 FR 48874, August 12, 2010). Section... Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch Limit) Harvested for Management... Administration (NOAA), Commerce. ACTION: Temporary rule; closure. SUMMARY: NMFS is closing the directed...

  6. 78 FR 62331 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-Annual Catch Limit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-17

    ... allocated to Area 1A is 29,775 mt, and 0 mt of the sub-ACL is set aside for research (78 FR 61828, October 4... Northeastern United States; Atlantic Herring Fishery; Sub-Annual Catch Limit (ACL) Harvested for Management... Administration (NOAA), Commerce. ACTION: Temporary rule; closure. SUMMARY: NMFS is closing the directed...

  7. 77 FR 61299 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-09

    ... research in the 2010-2012 specifications (75 FR 48874, August 12, 2010). Section 648.201 requires the... Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch Limit) Harvested for Management... Administration (NOAA), Commerce. ACTION: Temporary rule; closure. SUMMARY: NMFS is closing the directed...

  8. 78 FR 21071 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-09

    ...-ACL is set aside for research (75 FR 48874, August 12, 2010). The regulations at Sec. 648.201 require... Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch Limit) Harvested for Management... Administration (NOAA), Commerce. ACTION: Temporary rule; closure. SUMMARY: NMFS is closing the directed...

  9. 77 FR 66746 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-07

    ... research in the 2010-2012 specifications (75 FR 48874, August 12, 2010). However, due to an over-harvest in Area 1A in 2010, the FY 2012 sub-ACL in Area 1A was revised to 24,668 mt on February 24, 2012 (77 FR... Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch Limit) Harvested for...

  10. 76 FR 66654 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-27

    ... 1A is 26,546 mt, and 0 mt of the sub-ACL is set aside for research (75 FR 48874, August 12, 2010... Northeastern United States; Atlantic Herring Fishery; Sub-ACL (Annual Catch Limit) Harvested for Management... Administration (NOAA), Commerce. ACTION: Temporary rule; closure. SUMMARY: NMFS is closing the directed...

  11. Seismic Anisotropy and Mantle Flow Beneath Northeastern Africa and Arabia

    NASA Astrophysics Data System (ADS)

    Elsheikh, A.; Gao, S. S.; Liu, K. H.; Abdelsalam, M. G.

    2011-12-01

    The Afar Depression in NE Africa hosts the Earth's only RRR triple junction exposed on land, and is an ideal place to study processes involved in the transition from continental rifting to seafloor spreading. In order to image the crust and upper mantle structure under Afar with an unprecedented spatial resolution, eighteen broadband seismic stations were deployed between Dec. 2009 and May 2011 along an approximately 250 km long profile across the Tendaho Graben in central Afar as part of the Afar Lithosphere Imaging Experiment (ALIE). Here we present results from teleseismic shear-wave (XKS) splitting analysis using data from ALIE and all the available broadband seismic data archived at the IRIS Data Center. Several previous studies of shear wave splitting in the region suggested that the observed anisotropy could be attributed to preexisting Precambrian fabrics, while others argue that vertical magmatic dikes or rift parallel mantle flow are responsible for the observed anisotropy. All of those studies utilized limited quality and quantity of XKS measurements which resulted in the inconsistency of conclusions. This work presents about 200 XKS splitting measurements obtained using data from ALIE and over 400 measurements from other stations in Afar, the Main Ethiopian Rift (MER), Ethiopian Plateau, and the Arabian plate. A robust process to reliably assess and objectively rank XKS splitting parameters was used to produce the results. Manual screening was applied to the results of the automatic calculations to ensure that no high quality events were ignored and no low quality results were selected. This study found that the ~450 measurements in the Ethiopian Plateau and in the MER have insignificant azimuthal variations with MER dominated by a rift parallel fast direction suggestive of a single layer of anisotropy. In contrast, measurements in the Afar Depression show a systematic azimuthal dependence of splitting parameters with a 90-degree periodicity, which

  12. Modeling the impact of changes in Atlantic sea surface temperature on the climate of West Africa

    NASA Astrophysics Data System (ADS)

    Adeniyi, Mojisola O.

    2016-08-01

    This study assesses the impacts of warming/cooling of the Atlantic sea surface temperature (SST) on the climate of West Africa using Version 4.4 of Regional Climate Model (RegCM4.4) of International Center for Theoretical Physics, Trieste, Italy. The 1-2 K cooling and warming of the Atlantic SST both result in tripole temperature and precipitation change structure, having a northwest-southeast orientation over West Africa. Findings reveal that the responses of precipitation and temperature to the Atlantic SST cooling are opposite to those for the Atlantic SST warming and these responses intensify with increased warming/cooling of the Atlantic SST. The structure of the change in climate is attributed to the response of atmospheric/soil moisture gradient and orientation of orography in West Africa.

  13. Can seamounts provide a good habitat for polychaete annelids? Example of the northeastern Atlantic seamounts

    NASA Astrophysics Data System (ADS)

    Surugiu, Victor; Dauvin, Jean-Claude; Gillet, Patrick; Ruellet, Thierry

    2008-11-01

    Two seamount groups in the northeastern Atlantic were investigated during the 1980s and 1990s: the first was located along the Iberian and African coasts (Galicia, to the north of Portugal; and the Ampere, Gorringe, Josephine and Seine banks near the Madeira-Canary Islands) and the second was located offshore of the southern part of the Azores Islands, included the Atlantis, Hyeres, Irving, Meteor and Plato banks. Among the invertebrates, Annelida, specifically Polychaeta, were studied as surrogates for the biogeographical relationship between coastal and mid-oceanic seamounts in the northeastern Atlantic and the fauna in these areas. The dominant families were Onuphidae (27.46%), Syllidae (18.23%), Eunicidae (15.65%), Amphinomidae (11.45%) and Nereididae (5.61%), representing 78.4% of the total fauna. Data analyses clearly distinguished two seamount groups, one for coastal seamounts and the other offshore. Although the species distinguished and the family composition at the sampled sites were different (i.e., most diversified at the Josephine site and most impoverished at the Irving site), no coastal/offshore faunal impoverishment gradient could be identified. Thus, it seems that seamount environments do not favour any relationship between planktotrophic development and the direct development of polychaetes. Though the number of apparent endemic species was low (<7%), it remained in keeping with other invertebrate groups. Still, while seamounts may well encourage oceanic biodiversity in some zoological groups, this was clearly not the case for the polychaetes. We offer two explanations for this paradox: pelagic productivity and local environmental conditions.

  14. A new species of porcupine, genus Coendou (Rodentia: Erethizontidae) from the Atlantic forest of northeastern Brazil.

    PubMed

    Pontes, Antonio Rossano Mendes; Gadelha, José Ramon; Melo, Éverton R A; de Sá, Fabrício Bezerra; Loss, Ana Carolina; Caldara Junior, Vilacio; Costa, Leonora Pires; Leite, Yuri L R

    2013-01-01

    We report the discovery of a new species of Coendou (Rodentia, Erethizontidae), here designated Coendou speratus sp. nov. This small porcupine, locally known as coandumirim, is found in the Pernambuco Endemism Centre in the Atlantic coast of northeastern Brazil north of the São Francisco river, one of the most important known biodiversity hotspots. The geographic range of C. speratus overlaps with that of the larger, widespread C. prehensilis, but not with that of C. insidiosus from the southeastern Atlantic forest, nor with that of C. nycthemera, an eastern Amazonian species. Coendou speratus is a small-bodied, long-tailed species that appears to be completely spiny because it lacks long dorsal fur. The dorsal quills have conspicuously brownish red tips that contrast with the blackish dorsal background color. The new species is overall similar to C. nycthemera, but the dorsal body quills are typically tricolored in the former and bicolored in the latter. The new species is externally very distinct from C. insidiosus, especially because the latter has bicolored dorsal quills that are almost completely hidden beneath longer and homogeneous pale or dark hairs. PMID:26042302

  15. Iodine isotopes species fingerprinting environmental conditions in surface water along the northeastern Atlantic Ocean

    PubMed Central

    He, Peng; Hou, Xiaolin; Aldahan, Ala; Possnert, Göran; Yi, Peng

    2013-01-01

    Concentrations and species of iodine isotopes (127I and 129I) provide vital information about iodine geochemistry, environmental conditions and water masses exchange in oceans. Despite extensive investigations of anthropogenic 129I in the Arctic Ocean and the Nordic Seas, concentrations of the isotope in the Atlantic Ocean are, however, still unknown. We here present first data on 129I and 127I, and their species (iodide and iodate) in surface water transect along the northeastern Atlantic between 30° and 50°N. The results show iodate as the predominant species in the analyzed marine waters for both 127I and 129I. Despite the rather constant ratios of 127I−/127IO3−, the 129I−/129IO3− values reveal variations that apparently response to sources, environmental conditions and residence time. These findings provide a new tracer approach that will strongly enhance the application of anthropogenic 129I in ocean environments and impact on climate at the ocean boundary layer. PMID:24284916

  16. Perkinsosis in the clams Ruditapes decussatus and R. philippinarum in the Northeastern Atlantic and Mediterranean Sea: A review.

    PubMed

    Ruano, Francisco; Batista, Frederico M; Arcangeli, Giuseppe

    2015-10-01

    Perkinsosis is a disease of gastropod and bivalve molluscs caused by protozoan parasites of the Perkinsus genus. These parasites have been responsible for mass mortalities worldwide, with a significant impact in both fisheries and aquaculture, and resulting in severe economic losses. This review focuses mainly on current knowledge of diagnostic methods and on the distribution of Perkinsus spp. in the Northeastern Atlantic and Mediterranean Sea, which infect the grooved carpet shell clam Ruditapes decussatus and the Japanese carpet shell clam Ruditapes philippinarum. The association between perkinsosis and high mortality rates of R. decussatus and R. philippinarum in southern European countries such as Portugal and Italy is discussed as is the role of environmental factors in those mortality outbreaks. The putative introduction of Perkinsus olseni into the Northeastern Atlantic and Mediterranean Sea is also discussed, as are management strategies that could be used to mitigate the impact of perkinsosis in production of R. decussatus and R. philippinarum. PMID:26239015

  17. LINGUISTIC ANALYSES, THE NON-BANTU LANGUAGES OF NORTH-EASTERN AFRICA. HANDBOOK OF AFRICAN LANGUAGES SERIES.

    ERIC Educational Resources Information Center

    BRYAN, M.A.; TUCKER, A.N.

    THIS VOLUME PRESENTS THE LINGUISTIC MATERIAL ASSEMBLED BY THE AUTHORS (MUCH OF IT AT FIRST HAND) IN THE COURSE OF THEIR CLASSIFICATION OF THE NON-BANTU LANGUAGES OF NORTHEASTERN AFRICA. THIS MATERIAL, DEALING MAINLY WITH MORPHEMES AND GRAMMATICAL AND SYNTACTIC BEHAVIOR, INCLUDES DESCRIPTIONS OF THE FOLLOWING LANGUAGES--MORU-MANGBETU,…

  18. 75 FR 7435 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-19

    ... United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic Deep-Sea Red Crab Specifications... Atlantic deep-sea red crab fishery, including a target total allowable catch (TAC) and a fleet-wide days-at-sea (DAS) allocation. The implementing regulations for the Atlantic Deep-Sea Red Crab...

  19. The North Atlantic Oscillation: Impact on Snowfall Conditions in the Northeastern U.S

    NASA Astrophysics Data System (ADS)

    Budikova, D.; Widen, H.; Coleman, J. S.

    2013-12-01

    The North Atlantic Oscillation (NAO) is one of the main components of atmospheric circulation variability within the middle and high latitudes of the Northern Hemisphere, particularly impacting winter weather patterns in northeastern United States. Previous research has indicated greater snowfall totals and higher frequency of snowfall days in the Northeast during a NAO negative phase due to repeated polar outbreaks; yet, the NAO positive phase has also been associated with extreme snowfall events in this region. This study examines the relationship between the NAO and winter (December - February) snowfall totals in northeastern U.S. between 1961 and 2010. Two case studies of recent winter events with differing NAO phases were evaluated to provide insight on how both NAO phases can produce significant snowfall in portions of the Northeast. The analysis revealed an inverse relationship between the NAO phase and seasonal snowfall, with positive (negative) NAO index years associated with lower (higher) average snowfall and snowfall days. Significantly greater snowfall during the NAO negative phase was mainly located along the East Coast as well as the interior southern half of the study region. A composite analysis of various tropospheric variables (e.g., 500-hPa heights) showed NAO negative years produced greater snowfall due to more extreme weather conditions affecting the Northeast, such as below normal sea level pressure, a deepened mid-tropospheric trough and weaker upper-level westerlies that permitted more frequent polar outbreaks. The intrusion of cold polar air into the interior U.S. generates more extreme temperature gradients and produces snowfall farther south than the NAO positive phase. In addition, the eastward displacement of the storms in the NAO negative phase along with the available moisture from the Atlantic Ocean creates more snowfall along the East Coast. These results correspond to the spatial distribution of snowfall that occurred during the

  20. 78 FR 61838 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Removal of 2,000-lb (907.2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-04

    ... Federal Register (78 FR 21071, April 9, 2013) projecting that 95 percent (the closure threshold at the... Northeastern United States; Atlantic Herring Fishery; Removal of 2,000-lb (907.2-kg) Herring Trip Limit in Atlantic Herring Management Area 2 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic...

  1. Hydrography and through-flow in the north-eastern North Atlantic Ocean: the NANSEN project

    NASA Astrophysics Data System (ADS)

    van Aken, H. M.; Becker, G.

    The circulation and hydrography of the north-eastern North Atlantic has been studied with an emphasis on the upper layers and the deep water types which take part in the thermohaline overturning of the Oceanic Conveyor Belt. Over 900 hydrographic stations were used for this study, mainly from the 1987-1991 period. The hydrographic properties of Subpolar Mode Water in the upper layer, which is transported towards the Norwegian Sea, showed large regional variation. The deep water mass was dominated by the cold inflow of deep water from the Norwegian Sea and by a cyclonic recirculation of Lower Deep Water with a high Antarctic Bottom Water content. At intermediate levels the dominating water type was Labrador Sea Water with only minor influence of Mediterranean Sea Water. In the permanent pycnocline traces of Antarctic Intermediate Water were found. Geostrophic transports have been estimated, and these agreed in order of magnitude with the local heat budget, with current measurements, with data from surface drifters, and with the observed water mass modification. A total of 23 Sv of surface water entered the region, of which 20 Sv originated from the North Atlantic Current, while 3 Sv entered via an eastern boundary current. Of this total, 13 Sv of surface water left the area across the Reykjanes Ridge, and 7 Sv entered the Norwegian Sea, while 3 Sv was entrained by the cold overflow across the Iceland-Scotland Ridge. Approximately 1.4 Sv of Norwegian Sea Deep Water was involved in the overflow into the Iceland Basin, which, with about 1.1 Sv of entrained water and 1.1 Sv recirculating Lower Deep Water, formed a deep northern boundary current in the Iceland Basin. At intermediate depths, where Labrador Sea Water formed the dominant water type, about 2 Sv of entrained surface water contributed to a saline water mass which was transported westwards along the south Icelandic slope.

  2. Occurrence and characteristics of mesoscale eddies in the tropical northeastern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Schütte, Florian; Brandt, Peter; Karstensen, Johannes

    2016-05-01

    Coherent mesoscale features (referred to here as eddies) in the tropical northeastern Atlantic Ocean (between 12-22° N and 15-26° W) are examined and characterized. The eddies' surface signatures are investigated using 19 years of satellite-derived sea level anomaly (SLA) data. Two automated detection methods are applied, the geometrical method based on closed streamlines around eddy cores, and the Okubo-Weiß method based on the relation between vorticity and strain. Both methods give similar results. Mean eddy surface signatures of SLA, sea surface temperature (SST) and sea surface salinity (SSS) anomalies are obtained from composites of all snapshots around identified eddy cores. Anticyclones/cyclones are identified by an elevation/depression of SLA and enhanced/reduced SST and SSS in their cores. However, about 20 % of all anticyclonically rotating eddies show reduced SST and reduced SSS instead. These kind of eddies are classified as anticyclonic mode-water eddies (ACMEs). About 146 ± 4 eddies per year with a minimum lifetime of 7 days are identified (52 % cyclones, 39 % anticyclones, 9 % ACMEs) with rather similar mean radii of about 56 ± 12 km. Based on concurrent in situ temperature and salinity profiles (from Argo float, shipboard, and mooring data) taken inside of eddies, distinct mean vertical structures of the three eddy types are determined. Most eddies are generated preferentially in boreal summer and along the West African coast at three distinct coastal headland regions and carry South Atlantic Central Water supplied by the northward flow within the Mauretanian coastal current system. Westward eddy propagation (on average about 3.00 ± 2.15 km d-1) is confined to distinct zonal corridors with a small meridional deflection dependent on the eddy type (anticyclones - equatorward, cyclones - poleward, ACMEs - no deflection). Heat and salt fluxes out of the coastal region and across the Cape Verde Frontal Zone, which separates the shadow zone from

  3. Response of the Water Cycle of West Africa and Atlantic to Radiative Forcing by Saharan Dust

    NASA Technical Reports Server (NTRS)

    Lau, K. M.; Kim, Kyu-Myong; Sud, Yogesh C.; Walker, Gregory L.

    2010-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence in support of the "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summer, as a result of large-scale atmospheric feed back triggered by absorbing dust aerosols, rainfall and cloudiness are enhanced over the West Africa/Easter Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean. region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while long wave has the opposite response. The elevated dust layer warms the air over Nest Africa and the eastern Atlantic. The condensation heating associated with the induced deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface energy fluxes, resulting in cooling of the Nest African land and the eastern Atlantic, and a warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at 0.95 or higher.

  4. Full-depth temperature trends in the northeastern Atlantic through the early 21st century

    NASA Astrophysics Data System (ADS)

    Desbruyères, D. G.; McDonagh, E. L.; King, B. A.; Garry, F. K.; Blaker, A. T.; Moat, B. I.; Mercier, H.

    2014-11-01

    The vertical structure of temperature trends in the northeastern Atlantic (NEA) is investigated using a blend of Argo and hydrography data. The representativeness of sparse hydrography sampling in the basin mean is assessed using a numerical model. Between 2003 and 2013, the NEA underwent a strong surface cooling (0-450 m) and a significant warming at intermediate and deep levels (1000 m to 3000 m) that followed a strong cooling trend observed between 1988 and 2003. During 2003-2013, gyre-specific changes are found in the upper 1000 m (warming and cooling of the subtropical and subpolar gyres, respectively), while the intermediate and deep warming primarily occurred in the subpolar gyre, with important contributions from isopycnal heave and water mass property changes. The full-depth temperature change requires a local downward heat flux of 0.53 ± 0.06 W m-2 through the sea surface, and its vertical distribution highlights the likely important role of the NEA in the recent global warming hiatus.

  5. Pressure Indicators of Wood Resource Use in an Atlantic Forest Area, Northeastern Brazil

    NASA Astrophysics Data System (ADS)

    de Medeiros, Patrícia Muniz; de Almeida, Alyson Luiz Santos; da Silva, Taline Cristina; de Albuquerque, Ulysses Paulino

    2011-03-01

    Wood resources are often used to support the needs of the local population. In order to protect biodiversity and resources, conservation strategies need to consider what types of wood use have the strongest impacts on forested areas. This study aimed to identify the use categories that put higher pressure on an Atlantic forest region located in the municipality of Igarassu in Pernambuco, northeastern Brazil. To conduct the study, we measured the volume of all wood products in 62 surveyed residences and registered the average replacement time for such products. The fuelwood category was most important locally and accounted for 92% of annual wood consumption. However, the construction category harvests more destructively and concentrates on the consumption of a few wood species. Therefore we recommend the fuelwood category to be the main focus of conservation effforts. In addition, the most important species for construction purposes (e.g., Eschweilera ovata (Cambess.) Miers, Apuleia leiocarpa (Vogel) J.F. Macbr. and Pogonophora schomburgkiana Miers ex Benth) should also be considered as a priority for conservation.

  6. Pressure indicators of wood resource use in an Atlantic forest area, northeastern Brazil.

    PubMed

    de Medeiros, Patrícia Muniz; de Almeida, Alyson Luiz Santos; da Silva, Taline Cristina; de Albuquerque, Ulysses Paulino

    2011-03-01

    Wood resources are often used to support the needs of the local population. In order to protect biodiversity and resources, conservation strategies need to consider what types of wood use have the strongest impacts on forested areas. This study aimed to identify the use categories that put higher pressure on an Atlantic forest region located in the municipality of Igarassu in Pernambuco, northeastern Brazil. To conduct the study, we measured the volume of all wood products in 62 surveyed residences and registered the average replacement time for such products. The fuelwood category was most important locally and accounted for 92% of annual wood consumption. However, the construction category harvests more destructively and concentrates on the consumption of a few wood species. Therefore we recommend the fuelwood category to be the main focus of conservation effforts. In addition, the most important species for construction purposes (e.g., Eschweilera ovata (Cambess.) Miers, Apuleia leiocarpa (Vogel) J.F. Macbr. and Pogonophora schomburgkiana Miers ex Benth) should also be considered as a priority for conservation. PMID:21301833

  7. Multiple recurrent evolution of trophic types in northeastern Atlantic and Mediterranean seabreams (Sparidae, Percoidei).

    PubMed

    Hanel, R; Sturmbauer, C

    2000-03-01

    Seabreams are among the most valuable fish, not only for small-scale and semiindustrial fisheries but also for aquaculture throughout the Mediterranean. Nevertheless, their phylogenetic relationships are not at all clear. The current taxonomy is based solely on trophic morphology and rests on the assumption that each trophic type evolved only once from a less specialized ancestral condition. We analyzed a 486-bp segment of the mitochondrial 16S rDNA of all 24 seabream species described for the northeastern Atlantic and the Mediterranean to elucidate their generic and subfamily-level relationships. Three major mitochondrial lineages, each comprising species of different feeding strategy and dentition, were found that do not agree with the present taxonomic assignments. Most of the investigated genera were resolved paraphyletically, indicating that the structure and arrangement of oral teeth must have repeatedly evolved from a less specialized ancestral condition. Further, the genus Sparus was resolved as distantly related to the genus Pagrus, in that it was assigned to a different major mitochondrial lineage. Oblada melanura was consistently placed within the Diplodus radiation as sister group to Diplodus puntazzo. Our phylogenetic hypothesis thus suggests multiple independent origins of similar trophic specializations within the Sparidae and indicates that the currently recognized three or four subfamilies need to be redefined. PMID:10754071

  8. 75 FR 27219 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-14

    ... United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic Deep-Sea Red Crab Specifications...), Commerce. ACTION: Final rule. SUMMARY: NMFS issues final specifications for the 2010 Atlantic deep- sea red... document is also accessible via the Internet at http://www.nefmc.org . NMFS prepared a Final...

  9. Observation of the surface horizontal thermohaline variability at meso- to submesoscales in the North-Eastern Subtropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Kolodziejczyk, Nicolas; Reverdin, Gilles; Boutin, Jacqueline; Hernandez, Olga

    2015-04-01

    The seasonal variability of the surface horizontal thermohaline structure is investigated in the North-Eastern Atlantic Surface Salinity Maximum (SSM) at length scales from five to hundreds of kilometers, i.e. at submeso- to meso-scales. The near-surface temperature and salinity data from merchant ship thermosalinograph (TSG) transects across the Atlantic are used to compute the horizontal temperature, salinity and density fluctuations, and the density ratio. During late winter in the north-eastern SSM, thermohaline compensation is observed for wavelengths from 5 km to more than 200 km; in spite of large and sharp surface thermohaline fronts a weak density surface horizontal gradient is observed. Temperature and salinity exhibit an energetic spectra in k-2 slope scale between 20-100 km scale and a steeper slope at shorter wavelengths, while density spectra exhibit lower energy level with a clear k-3 slope below 20 km, consistent with interior quasi-geostrophic turbulence. During summer in the north-eastern SSM, salinity and temperature gradients are no longer compensated due to strong atmospheric heating of the upper ocean. In comparison with winter, the surface density spectrum is enhanced with a flatter slope between k-2-k-3 between 5 and 20 km.

  10. Observation of the surface horizontal thermohaline variability at mesoscale to submesoscale in the north-eastern subtropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Kolodziejczyk, Nicolas; Reverdin, Gilles; Boutin, Jacqueline; Hernandez, Olga

    2015-04-01

    The seasonal variability of the surface horizontal thermohaline structure is investigated in the north-eastern Atlantic Surface Salinity Maximum (SSM) at length scales from five to hundreds of kilometers, i.e., at submesoscale to mesoscale. The near-surface temperature and salinity data from merchant ship thermosalinograph (TSG) transects across the Atlantic are used to compute the horizontal temperature, salinity and density fluctuations, and the density ratio. During late winter in the north-eastern SSM, thermohaline compensation is observed for wavelengths from 5 km to more than 200 km; in spite of large and sharp surface thermohaline fronts, a weak density surface horizontal gradient is observed. Temperature and salinity exhibit an energetic spectra in k-2 slope scale between 20-100 km scale and a steeper slope at shorter wavelengths, while density spectra exhibit lower energy level with a clear k-3 slope below 20 km, consistent with interior quasigeostrophic turbulence. During summer in the north-eastern SSM, salinity and temperature gradients are no longer compensated due to strong atmospheric heating of the upper ocean. In comparison with winter, the surface density spectrum is enhanced with a flatter slope between k-2 and k-1 between 5 and 20 km.

  11. Vertical Distribution of Heterotrophic Bacteria and Their Culturability In The Northeastern Atlantic (pomme 0 Cruise)

    NASA Astrophysics Data System (ADS)

    Denis, M.; Moumas, M.; Bianchi, M.

    In the frame of POMME (Programme Océanographie Multidisciplinaire Méso- Echelle) a French oceanographic programme in the Northeastern Atlantic (39-45N and 15-21W), the vertical distribution of heterotrophic bacteria and their culturability were investigated by combining different independent approaches during the POMME 0 cruise in fall 2000. Bacterial abundances and biomasses were determined by flow cytometric analysis of seawater samples, fixed, frozen and stored in liquid nitrogen un- til their analysis in the laboratory. Cells were stained with the green fluorescent probe SYBR Green IIZ´ (Molecular Probes), a specific probe for nucleic acids. The enumer- ated bacteria were pooled into two fractions according to their DNA content. Bacteria with the higher DNA content (HDNA) are considered as the fraction potentially able of undergoing division, whereas cells with the lower DNA content (LDNA) constitute an inactive fraction (Gasol et al., 1999). The viability of the collected bacteria was determined by using the method of Bianchi &Giuliano (1996) based on the formation of micro-colonies. The percentages of dividing bacteria were calculated with respect to the numbers of HDNA bacteria instead of the total counts which contained the irrel- evant LDNA cells. The percentage of dividing bacteria was larger when the bacteria population was dominated by HDNA bacteria. This result suggests that a bacterial population composed mainly of HDNA cells will have a larger capacity to divide than otherwise. The distribution of the bacterial activity at the sampled stations showed that conditions for the heterotrophic bacteria development were more favorable in the south western zone of the study area. The observed bacterial abundances were in the range 3.7 104 - 5.3 105 cells cm-3. The percentages of the LDNA fractions were in the range 40 - 90%, suggesting the occurrence of a declining ecosystem. The installa- tion of an oligotrophic system was supported by the observation of

  12. Temperature-salinity distribution in the northeastern Atlantic from ship and Argo vertical casts

    NASA Astrophysics Data System (ADS)

    Bashmachnikov, I.; Neves, F.; Nascimento, Â.; Medeiros, J.; Ambar, I.; Dias, J.; Carton, X.

    2015-03-01

    The present study defines new interpolation functions for hydrological data. These functions are applied to generate climatological maps of temperature-salinity distribution with a 25 m depth interval and a 30 km space interval (MEDTRANS data set). The data undergo rigorous initial data quality control, having passed several filtering procedures. The gridding is done on neutral density surfaces, which allows better representation of thermohaline fronts for the same gridding radius. The multi-pass Barnes optimum interpolation procedure with spatially variable size of the gridding window is used. The shape of the window accounts for the dominant along-isobath direction of water mass transport over steeply sloping topography. A local ratio of topographic to planetary β-effects is used to define the shape of the window as a function of the relative importance of the topographic influence. The N/f ratio is applied to account for the baroclinic compensation decay of the topographic influence on water mass transport with the distance from the bottom. The gridded fields are available at the website of the Centre of Oceanography of the University of Lisbon (http://co.fc.ul.pt/en/data). The MEDTRANS climatology gives more details of the distribution of water characteristics in the subtropical northeastern Atlantic than other alternative climatologies and is able to reproduce a number of dynamic features described in the literature: the acceleration in the meanders of the Azores current; the cyclonic gyre in the Gulf of Cadiz; and the splitting and separation of the Mediterranean Water (MW) outflow in two veins near the Gorringe and Galicia banks. Seasonal climatologies, computed for the warm (May-October) and cold (November-April) seasons, reveal stronger zonal extension of the upper ocean patterns during the warm season, as compared to the cold one.

  13. BIODIVERSITY OF CORALLINE ALGAE IN THE NORTHEASTERN ATLANTIC INCLUDING CORALLINA CAESPITOSA SP. NOV. (CORALLINOIDEAE, RHODOPHYTA)(1).

    PubMed

    Walker, Rachel H; Brodie, Juliet; Russell, Stephen; Irvine, Linda M; Orfanidis, Sotiris

    2009-02-01

    The Corallinoideae (Corallinaceae) is represented in the northeastern Atlantic by Corallina officinalis L.; Corallina elongata J. Ellis et Sol.; Haliptilon squamatum (L.) H. W. Johans., L. M. Irvine et A. M. Webster; and Jania rubens (L.) J. V. Lamour. The delimitation of these geniculate coralline red algae is based primarily on morphological characters. Molecular analysis based on cox1 and 18S rRNA gene phylogenies supported the division of the Corallinoideae into the tribes Janieae and Corallineae. Within the Janieae, a sequence difference of 46-48 bp (8.6%-8.9%) between specimens of H. squamatum and J. rubens in the cox1 phylogeny leads us to conclude that they are congeneric. J. rubens var. rubens and J. rubens var. corniculata (L.) Yendo clustered together in both phylogenies, suggesting that for those genes, there was no genetic basis for the morphological variation. Within the Corallineae, it appears that in some regions, the name C. elongata has been misapplied. C. officinalis samples formed two clusters that differed by 45-54 bp (8.4%-10.0%), indicating species-level divergence, and morphological differences were sufficient to define two species. One of these clusters was consistent with the morphology of the type specimen of C. officinalis (LINN 1293.9). The other species cluster is therefore described here as Corallina caespitosa sp. nov. This study has demonstrated that there is a clear need for a revision of the genus Corallina to determine the extent of "pseudocryptic" diversity in this group of red algae. PMID:27033664

  14. Winter distribution of algal pigments in small- and large-size particles in the northeastern Atlantic

    NASA Astrophysics Data System (ADS)

    Méjanelle, L.; Laureillard, J.; Fillaux, J.; Saliot, A.; Lambert, C.

    1995-01-01

    Particles were collected by filtration on GF/F filters and by vertical hauls of 50 μm mesh-sized net throughout the water column (50-1700 m) in the northeastern Atlantic in January 1989 during the Medatlante t cruise, in the framework of the French JGOFS program. Particles were analysed for their organic carbon and algal chlorophyll and carotenoid pigments by high-performance liquid chromatography coupled with UV absorbance and fluorescence detection. Complementary analyses were performed on a surface sample for sterols and fatty acids by gas chromatography and gas chromatography/mass spectrometry. Organic carbon concentrations were 2-3 orders of magnitude higher in GF/F (10-50 μg l-1) than in net particles (0.01-0.06μg l-1). The same ratio was encountered for pigments: 4-603 ng l-1 and 0.003-0.037 ng l1¯, respectively. Among 11 GF/F samples collected between 500 and 1700 m, four samples contained pigments in detectable amounts (4-106 ng l-1). Their pigment distribution pattern was close to deep GF/F samples, but differed from the pigment pattern of deep net-collected particles, mainly composed of fecal pellets. This latter sinking material was enriched in chlorophyll degradation pigments and showed higher values of the ratio (sum of carotenoids)/(sum of chlorophylls) than those observed in small-size particles. The combined information from pigments, sterols and fatty acids shows that Prymnesiophytes in a post bloom situation contributed to a major part of the surface autotrophs. Two processes of rapid transfer of organic matter between the surface and the deep Mediterranean water are discussed: fecal pellets of herbivorous plankton and sedimentation of aggregates partly linked to the presence of Prymnesiophytes.

  15. The morphology of saccular otoliths as a tool to identify different mugilid species from the Northeastern Atlantic and Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Callicó Fortunato, Roberta; Benedito Durà, Vicent; Volpedo, Alejandra

    2014-06-01

    In the Northeastern Atlantic and Mediterranean Sea there are 8 species of the Mugilidae family: Mugil cephalus, Liza aurata, Liza ramada, Oedalechilus labeo, Chelon labrosus, Liza saliens, Liza carinata and Liza haematocheila. The identification of mugilids is very important for local fisheries management and regulations, but it is difficult using gross morphological characters. This work aims to contribute to the identification of mullets present in the Northeastern Atlantic Ocean and Mediterranean Sea using saccular otolith features of each species. Specimens of C. labrosus, L. aurata, L. ramada, L. saliens and M. cephalus were obtained from Delta del Ebro (40°38'N-0°44'E) in artisanal catches. For L. carinata and O. labeo photographs extracted from AFORO online database were used. L. haematocheila was not studied for lack of otolith samples. A general pattern of the saccular otoliths for this family was identified: the shape of the otoliths are rectangular to oblong with irregular margins; they present a heterosulcoid, ostial sulcus acusticus, with an open funnel-like ostium to the anterior margin and a closed, tubular cauda, ending towards the posterior ventral corner, always larger than the ostium. In the present study, the mugilid species could be recognized using their saccular otolith morphology. Here we give the first key to identify Northeastern Atlantic and Mediterranean mullets. The distinctive features between the species were the position and centrality of the sulcus, the curvature of the cauda, the presence of areal depositions and plateaus, and the type of anterior and posterior regions. These features could be used not only to reinforce the identification keys through morphological and meristic characters of the species, but also to identify the species consumed by piscivores, being the otoliths the only identifiable remains of the individuals.

  16. Congruent phylogeographical patterns of eight tree species in Atlantic Central Africa provide insights into the past dynamics of forest cover.

    PubMed

    Dauby, G; Duminil, J; Heuertz, M; Koffi, G K; Stévart, T; Hardy, O J

    2014-05-01

    Cycles of Quaternary climatic change are assumed to be major drivers of African rainforest dynamics and evolution. However, most hypotheses on past vegetation dynamics relied on palaeobotanical records, an approach lacking spatial resolution, and on current patterns of species diversity and endemism, an approach confounding history and environmental determinism. In this context, a comparative phylogeographical study of rainforest species represents a complementary approach because Pleistocene climatic fluctuations may have left interpretable signatures in the patterns of genetic diversity within species. Using 1274 plastid DNA sequences from eight tree species (Afrostyrax kamerunensis, A. lepidophyllus, Erythrophleum suaveolens, Greenwayodendron suaveolens, Milicia excelsa, Santiria trimera, Scorodophloeus zenkeri and Symphonia globulifera) sampled in 50 populations of Atlantic Central Africa (ACA), we averaged divergence across species to produce the first map of the region synthesizing genetic distinctiveness and standardized divergence within and among localities. Significant congruence in divergence was detected mostly among five of the eight species and was stronger in the northern ACA. This pattern is compatible with a scenario of past forest fragmentation and recolonization whereby forests from eastern Cameroon and northeastern Gabon would have been more affected by past climatic change than those of western Cameroon (where one or more refugia would have occurred). By contrast, southern ACA (Gabon) displayed low congruence among species that may reflect less drastic past forest fragmentation or a more complex history of vegetation changes. Finally, we also highlight the potential impact of current environmental barriers on spatial genetic structures. PMID:24655106

  17. 77 FR 58507 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ...-9135. SUPPLEMENTARY INFORMATION: Background Amendment 11 to the MSB FMP (76 FR 68642, November 7, 2011... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Framework Adjustment 5 AGENCY... Adjustment 5 to the Atlantic Mackerel, Squid, and Butterfish Fishery Management Plan (MSB FMP), which...

  18. 76 FR 74724 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-01

    ... November 7, 2011 (76 FR 68642). Details regarding the measures in Amendment 11 are in the final rule and... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Amendment 11 AGENCY: National Marine... implementing Amendment 11 to the Atlantic Mackerel, Squid, and Butterfish (MSB) Fishery Management Plan...

  19. 75 FR 69014 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Total Allowable Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-10

    ... August 12, 2010 (75 FR 48874). The 2010 total TAC is 91,200 mt, allocated to the herring management areas... United States; Atlantic Herring Fishery; Total Allowable Catch Harvested for Management Area 1A AGENCY.... ACTION: Temporary rule; notification of trip limit reduction in Area 1A of the Atlantic Herring...

  20. 75 FR 56016 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Total Allowable Catch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-15

    ... to Area 1B (75 FR 48874, August 12, 2010) is 4,362 mt; 0 mt of the TAC is set aside for research... United States; Atlantic Herring Fishery; Total Allowable Catch Harvested for Management Area 1B AGENCY...) of Atlantic herring in or from Management Area 1B (Area 1B) per trip or calendar day until January...

  1. 78 FR 3401 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-16

    ... the human environment of alternative measures to protect deep-sea corals in the Mid-Atlantic region... identifying the significant issues related to deep-sea coral protections in the Mid-Atlantic. This notice is..., and Butterfish (MSB), which addresses protections of deep-sea corals from the impacts of fishing...

  2. 75 FR 49420 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-13

    ... establish a target TAC greater than that recommended by the Council, the initial final rule (75 FR 27219... on June 22, 2010 (75 FR 35435), requesting public comment on the revised recommended catch level... (TAC) and corresponding fleet days-at-sea (DAS) allocation for the Atlantic deep- sea red crab...

  3. 75 FR 65452 - Fisheries of the Northeastern United States; Atlantic Surfclam and Ocean Quahog Fisheries; Notice...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-25

    ... National Oceanic and Atmospheric Administration RIN 0648-XZ32 Fisheries of the Northeastern United States...: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce... their fishing year 2011 cage tags from the National Band and Tag Company. The intent of this notice...

  4. 78 FR 60255 - Fisheries of the Northeastern United States; Atlantic Surfclam and Ocean Quahog Fisheries; Notice...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-01

    ... National Oceanic and Atmospheric Administration RIN 0648-XC861 Fisheries of the Northeastern United States...: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce... their fishing year 2014 (January 1, 2014-December 31, 2014) cage tags from the National Band and...

  5. Wood litter consumption by three species of Nasutitermes termites in an area of the Atlantic Coastal Forest in northeastern Brazil.

    PubMed

    Vasconcellos, Alexandre; Moura, Flávia Maria da Silva

    2010-01-01

    Termites constitute a considerable fraction of the animal biomass in tropical forest, but little quantitative data are available that indicates their importance in the processes of wood decomposition. This study evaluated the participation of Nasutitermes corniger (Motschulsky) (Isoptera: Termitidae), N. ephratae (Holmgren), and N. macrocephalus (Silvestri) in the consumption of the wood litter in a remnant area of Atlantic Coastal Forest in northeastern Brazil. The populations of this species were quantified in nests and in decomposing tree trunks, while the rate of wood consumption was determined in the laboratory using wood test-blocks of Clitoria fairchildiana Howard (Fabales: Fabaceae), Cecropia sp. (Urticales: Cecropiaceae), and Protium heptaphyllum (Aublet) Marchand (Sapindales: Burseraceae). The abundance of the three species of termites varied from 40.8 to 462.2 individuals/m(2). The average dry wood consumption for the three species was 9.4 mg/g of termites (fresh weight)/day, with N. macrocephalus demonstrating the greatest consumption (12.1 mg/g of termite (fresh weight)/day). Wood consumption by the three species of Nasutitermes was estimated to be 66.9 kg of dry wood /ha/year, corresponding to approximately 2.9% of the annual production of wood-litter in the study area. This consumption, together with that of the other 18 exclusively wood-feeders termite species known to occur in the area, indicates the important participation of termites in removing wood-litter within the Atlantic Coastal Forest domain. PMID:20673190

  6. 77 FR 71720 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-04

    ... on September 21, 2012 (77 FR 58507). Additional background information and detail on why and how... 11 to the MSB FMP (76 FR 68642, November 7, 2011) implemented a three-tiered mackerel limited access... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Framework Adjustment 5...

  7. 76 FR 65697 - Fisheries of the Northeastern United States; Atlantic Surfclam and Ocean Quahog Fisheries; 2012...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-24

    ...; Atlantic Surfclam and Ocean Quahog Fisheries; 2012 Cage Tags AGENCY: National Marine Fisheries Service... provide fishing year 2012 cage tags. SUMMARY: NMFS informs surfclam and ocean quahog individual... (January 1, 2012-December 31, 2012) cage tags from the National Band and Tag Company. The intent of...

  8. 77 FR 64316 - Fisheries of the Northeastern United States; Atlantic Surfclam and Ocean Quahog Fisheries; Notice...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-19

    ...; Atlantic Surfclam and Ocean Quahog Fisheries; Notice That Vendor Will Provide Year 2013 Cage Tags AGENCY.... ACTION: Notice of vendor to provide fishing year 2013 cage tags. SUMMARY: NMFS informs surfclam and ocean... their fishing year 2013 (January 1, 2013-December 31, 2013) cage tags from the National Band and...

  9. 77 FR 23635 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-20

    ..., 2011 (77 FR 16472). This action established catch levels for the 2012 fishing year for mackerel and... regulatory text in the final rule for 2012 Specifications for the Atlantic Mackerel, Squid, and Butterfish.... While the final rule revised the regulatory text regarding closures of the commercial fishery at 50...

  10. 78 FR 53404 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-29

    ... INFORMATION: Background On June 9, 2010 (75 FR 32745), the Council published a notice of intent (NOI) to... review by the Secretary of Commerce, was published in the Federal Register on August 12, 2013 (78 FR... Atlantic Herring FMP (Amendment 5). A proposed rule to implement Amendment 5 (78 FR 33020) was published...

  11. 77 FR 73957 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Closure of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-12

    ... Adjustment 22 to the Scallop FMP (Framework 22) (76 FR 43774; July 21, 2011), which used 2010 scallop... policy guidelines for the use of emergency rules (62 FR 44421; August 21, 1997) specify the following... United States; Atlantic Sea Scallop Fishery; Closure of the Elephant Trunk Area AGENCY: National...

  12. 75 FR 5537 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-03

    ... was published on November 12, 2009 (74 FR 58234), and the public comment period for the proposed rule... revised through Amendment 9 to the FMP (Amendment 9) (73 FR 37382, July 1, 2008) to reflect the analytical... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Specifications and Management...

  13. 75 FR 43090 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-23

    ...-2179, fax (978) 281-9135. SUPPLEMENTARY INFORMATION: On June 30, 2010 (75 FR 37739), a temporary rule... equivalent is 10,770 mt. Correction In rule FR Doc. 2010-15933 published on June 30, 2010, (75 FR 37739) make... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Adjustment to the Loligo Trimester...

  14. 75 FR 1024 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-08

    ..., 2003 (68 FR 27516), NMFS published, at the request of the Council, an ANPR indicating that the Council... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Control Date for Loligo and Illex Squid AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric...

  15. 75 FR 37739 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-30

    ... Butterfish Fisheries in the Federal Register on February 3, 2010 (75 FR 5537). The final rule modified... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Adjustment to the Loligo Trimester 2... Fishing Year (FY) Trimester 2 and 3 Loligo squid quotas. This action complies with the 2010...

  16. 76 FR 13887 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish (MSB...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-15

    ... Plan (FMP) (76 FR 8306; February 14, 2011). Butterfish catches have been constrained to low levels... days. ] NMFS policy guidelines for the use of emergency rules (62 FR 44421; August 21, 1997) specify... United States; Atlantic Mackerel, Squid, and Butterfish (MSB) Fishery; Revision of 2011...

  17. 77 FR 74159 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-13

    ... Mackerel, Squid, and Butterfish (MSB) Fishery Management Plan (FMP) (75 FR 11441, March 11, 2010) as a... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Framework Adjustment 7 AGENCY... on the longfin squid fishery from a catch cap to a discard cap in Framework Adjustment 7 to...

  18. 75 FR 51683 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ... FR 5537, February 3, 2010). Section 648.22 requires NMFS to close the directed butterfish fishery in... United States; Atlantic Mackerel, Squid, and Butterfish Fisheries; Closure of the Directed Butterfish..., Squid, and Butterfish Fishery Management Plan (FMP). The procedures for setting the annual...

  19. 76 FR 8306 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-14

    ... management measures was published on November 17, 2010 (75 FR 70187), and the public comment period for the..., established in 2010 by Amendment 10 to the FMP (Amendment 10) (75 FR 11441, March 11, 2010), could result in a...- Atlantic RSA Program through the Federal Register (75 FR 3092, January 19, 2010), and reviewed them in...

  20. Seroprevalence of Toxoplasma gondii and Neospora caninum in north-eastern Atlantic Harbor seal

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antibodies to Toxoplasma gondii and Neospora caninum were determined in serum samples from 47 grey seals (Halichoerus grypus) and 56 harbor seals (Phoca vitulina vitulina) from the Atlantic coasts of United Kingdom and France. Antibodies to T. gondii assayed by the modified agglutination test (MAT) ...

  1. 77 FR 51858 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-27

    ..., NMFS published a proposed rule (76 FR 66260) that included the Mid-Atlantic Fishery Management Council... butterfish specifications (March 21, 2012; 77 FR 16472) that temporarily reinstated the status quo butterfish..., 2011; 76 FR 66260), there is no need to re-propose these final specifications. NMFS used the...

  2. 78 FR 46897 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Framework Adjustment 2 and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-02

    ... FYs 2013-2015. The Council recommended and NMFS is proposing a 3-percent herring research set-aside (RSA) for all management areas for fishing years 2014-2015. The research set-aside was established in... to the Atlantic herring Fishery Management Plan and the 2013-2015 fishery specifications for...

  3. 78 FR 3346 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-16

    ...), Commerce. ACTION: Final rule. SUMMARY: NMFS is implementing 2013-2015 specifications and management... recommending ABCs for the 2013-2015 Atlantic mackerel (mackerel) and 2013 butterfish specifications. A proposed rule for 2013 MSB specifications and management measures was published on November 19, 2012 (77...

  4. Large bio-geographical shifts in the north-eastern Atlantic Ocean: From the subpolar gyre, via plankton, to blue whiting and pilot whales

    NASA Astrophysics Data System (ADS)

    Hátún, H.; Payne, M. R.; Beaugrand, G.; Reid, P. C.; Sandø, A. B.; Drange, H.; Hansen, B.; Jacobsen, J. A.; Bloch, D.

    2009-03-01

    Pronounced changes in fauna, extending from the English Channel in the south to the Barents Sea in the north-east and off Greenland in the north-west, have occurred in the late 1920s, the late 1960s and again in the late 1990s. We attribute these events to exchanges of subarctic and subtropical water masses in the north-eastern North Atlantic Ocean, associated with changes in the strength and extent of the subpolar gyre. These exchanges lead to variations in the influence exerted by the subarctic or Lusitanian biomes on the intermediate faunistic zone in the north-eastern Atlantic. This strong and persistent bottom-up bio-physical link is demonstrated using a numerical ocean general circulation model and data on four trophically connected levels in the food chain - phytoplankton, zooplankton, blue whiting, and pilot whales. The plankton data give a unique basin-scale depiction of these changes, and a long pilot whale record from the Faroe Islands offers an exceptional temporal perspective over three centuries. Recent advances in simulating the dynamics of the subpolar gyre suggests a potential for predicting the distribution of the main faunistic zones in the north-eastern Atlantic a few years into the future, which might facilitate a more rational management of the commercially important fisheries in this region.

  5. Spatial and seasonal variations in abundance and spectral characteristics of phycoerythrins in the tropical northeastern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Lantoine, François; Neveux, Jacques

    1997-02-01

    A simple and rapid spectrofluorimetric method to quantify phycoerythrins (PEs) from the area below the fluorescence excitation spectra is proposed. In contrast to other methods which used measurements at fixed wavelengths, this method takes into account the spectral diversity of these pigments. It was applied in the tropical northeastern Atlantic during the EUMELI program at three stations which were characterized by different trophic status (eutrophic, mesotrophic and oligotrophic). Sampling was made at various periods of the year. The results showed the constant presence of phycoerythrin nearly always associated with cyanobacteria ( Synechococcus). At the oligotrophic site, high phycourobilin (PUB) populations and a great stability in the abundance and spectral characteristics of PE were observed. The eutrophic and mesotrophic sites showed higher PE abundance and spectral variability, and were essentially dominated by high phycoerythrobilin (PEB) populations. A general increase with depth in the PUB/PEB ratio at the eutrophic and mesotrophic sites was observed. This increase could be regular or relatively sharp through physical discontinuity (thermocline or halocline). The presence of Cryptophyceae PE was occasionally noted. The PE diversity was most probably related to the presence of different populations, but some variations could be also influenced by photoacclimation processes. Further progress in the spectrofluorimetric analysis of PE could be achieved by using three-dimensional spectra.

  6. Multiple Beneficial Lipids Including Lecithin Detected in the Edible Invasive Mollusk Crepidula fornicata from the French Northeastern Atlantic Coast

    PubMed Central

    Dagorn, Flore; Buzin, Florence; Couzinet-Mossion, Aurélie; Decottignies, Priscilla; Viau, Michèle; Rabesaotra, Vony; Barnathan, Gilles; Wielgosz-Collin, Gaëtane

    2014-01-01

    The invasive mollusk Crepidula fornicata, occurring in large amounts in bays along the French Northeastern Atlantic coasts, may have huge environmental effects in highly productive ecosystems where shellfish are exploited. The present study aims at determining the potential economic value of this marine species in terms of exploitable substances with high added value. Lipid content and phospholipid (PL) composition of this mollusk collected on the Bourgneuf Bay were studied through four seasons. Winter specimens contained the highest lipid levels (5.3% dry weight), including 69% of PLs. Phosphatidylcholine (PC) was the major PL class all year, accounting for 63.9% to 88.9% of total PLs. Consequently, the winter specimens were then investigated for PL fatty acids (FAs), and free sterols. Dimethylacetals (DMAs) were present (10.7% of PL FA + DMA mixture) revealing the occurrence of plasmalogens. More than forty FAs were identified, including 20:5n-3 (9.4%) and 22:6n-3 (7.3%) acids. Fourteen free sterols were present, including cholesterol at 31.3% of the sterol mixture and about 40% of phytosterols. These data on lipids of C. fornicata demonstrate their positive attributes for human nutrition and health. The PL mixture, rich in PC and polyunsaturated FAs, offers an interesting alternative source of high value-added marine lecithin. PMID:25532566

  7. Lidar Observations of Tropospheric Aerosols Over Northeastern South Africa During the ARREX and SAFARI-2000 Dry Season Experiments

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Welton, Ellsworth J.; Spinhirne, James D.; Ji, Qiang; Tsay, Si-Chee; Piketh, Stuart J.; Barenbrug, Marguerite; Holben, Brent; Starr, David OC. (Technical Monitor)

    2002-01-01

    During the ARREX-1999 and SAFARI-2000 Dry Season experiments a micropulse lidar (523 nm) instrument was operated at the Skukuza Airport in northeastern South Africa. The Mar was collocated with a diverse array of passive radiometric equipment. For SAFARI-2000 the processed Mar data yields a daytime time-series of layer mean/derived aerosol optical properties, including extinction-to-backscatter ratios and vertical extinction cross-section profile. Combined with 523 run aerosol optical depth and spectral Angstrom exponent calculations from available CIMEL sun-photometer data and normalized broadband flux measurements the temporal evolution of the near surface aerosol layer optical properties is analyzed for climatological trends. For the densest smoke/haze events the extinction-to-backscatter ratio is found to be between 60-80/sr, and corresponding Angstrom exponent calculations near and above 1.75. The optical characteristics of an evolving smoke event from SAFARI-2000 are extensively detailed. The advecting smoke was embedded within two distinct stratified thermodynamic layers, causing the particulate mass to advect over the instrument array in an incoherent manner on the afternoon of its occurrence. Surface broadband flux forcing due to the smoke is calculated, as is the evolution in the vertical aerosol extinction profile as measured by the Han Finally, observations of persistent elevated aerosol during ARREX-1999 are presented and discussed. The lack of corroborating observations the following year makes these observation; both unique and noteworthy in the scope of regional aerosol transport over southern Africa.

  8. Ecology and geography of avian influenza (HPAI H5N1) transmission in the Middle East and northeastern Africa

    PubMed Central

    Williams, Richard AJ; Peterson, A Townsend

    2009-01-01

    Background The emerging highly pathogenic avian influenza strain H5N1 ("HPAI-H5N1") has spread broadly in the past decade, and is now the focus of considerable concern. We tested the hypothesis that spatial distributions of HPAI-H5N1 cases are related consistently and predictably to coarse-scale environmental features in the Middle East and northeastern Africa. We used ecological niche models to relate virus occurrences to 8 km resolution digital data layers summarizing parameters of monthly surface reflectance and landform. Predictive challenges included a variety of spatial stratification schemes in which models were challenged to predict case distributions in broadly unsampled areas. Results In almost all tests, HPAI-H5N1 cases were indeed occurring under predictable sets of environmental conditions, generally predicted absent from areas with low NDVI values and minimal seasonal variation, and present in areas with a broad range of and appreciable seasonal variation in NDVI values. Although we documented significant predictive ability of our models, even between our study region and West Africa, case occurrences in the Arabian Peninsula appear to follow a distinct environmental regime. Conclusion Overall, we documented a variable environmental "fingerprint" for areas suitable for HPAI-H5N1 transmission. PMID:19619336

  9. Preliminary report on geology along Atlantic Continental Margin of northeastern United States

    USGS Publications Warehouse

    Minard, J.P.; Perry, W.J.; Weed, E.G.A.; Rhodehamel, E.C.; Robbins, E.I.; Mixon, R.B.

    1974-01-01

    The U.S. Geological Survey is conducting a geologic and geophysical study of the northeastern United States outer continental shelf and the adjacent slope from Georges Bank to Cape Hatteras. The study also includes the adjacent coastal plain because it is a more accessible extension of the shelf. The total study area is about 324,000 sq km, of which the shelf and slope constitute about 181,000 sq km and the coastal plain constitutes 143,000 sq km. The shelf width ranges from about 30 km at Cape Hatteras to about 195 km off Raritan Bay and on Georges Bank. Analyses of bottom samples make it possible to construct a preliminary geologic map of the shelf and slope to a water depth of 2,000 m. The oldest beds cropping out in the submarine canyons and on the slope are of early ate Cretaceous age. Beds of Early Cretaceous and Jurassic age are present in deep wells onshore and probably are present beneath the shelf in the area of this study. Such beds are reported beneath the Scotian shelf on the northeast where they include limestone, salt, and anhydrite. Preliminary conclusions suggest a considerably thicker Mesozoic sedimentary sequence than has been described previously. The region is large; the sedimentary wedge is thick; structures seem favorable; and the hydrocarbon potential may be considerable.

  10. NEAMWave12: The First Tsunami Exercise in the North-eastern Atlantic, the Mediterranean and Connected Seas

    NASA Astrophysics Data System (ADS)

    Necmioglu, Ocal; Matias Matias, Luis; Schindelé, François; Behrens, Jörn; Tinti, Stefano; Chouliaras, Gerasimos; Melis, Nicos; Carrilho, Fernando; Santoro, Francesca; Rudloff, Alexander; Crochet, Emilie; Gonzalez, Mauricio

    2013-04-01

    The first tsunami exercise of the Tsunami Early Warning and Mitigation System in the North-eastern Atlantic, the Mediterranean and connected seas (NEAMTWS) has been conducted on 27-28 November 2012 involving 19 of the 39 member countries of the Intergovernmental Coordination Group (ICG) for NEAMTWS. NEAMWave12 involved the simulation of the assessment of a tsunami, based on an earthquake-driven scenario followed by alert message dissemination by Candidate Tsunami Watch Provider (CTWP) (Phase A) and continued with the simulation of the National Tsunami Warning Center's/Tsunami Warning Focal Point's (NTWC/TWFP) and Civil Protection Authoritie's (CPA) actions (Phase B), as soon as the message produced in Phase A has been received. There were four earthquake triggered tsunami scenarios in NEAMWave12 in different parts of the NEAM Region, where each CTWP (CENALT-France, NOA-Greece, IPMA-Portugal and KOERI-Turkey) was responsible for a single scenario. The CENALT Scenario was based on a plausible worst-case scenario of magnitude 7.5 along the Western Mediterranean Algerian margin at a fault located close to 21-22 August 1856 Jijel earthquakes. The NOA scenario was based on an earthquake similar to the well-known Amorgos earthquake, which was followed by a tsunami that devastated the Aegean Sea on 9 July 1956. The IPMA scenario was based on the 1 November 1755 Lisbon event with the assumption that the event represents the worst-case tsunami scenario impacting the NE Atlantic region. Finally, the KOERI scenario was based on a Mw=8.4 worst-case interpretation of the 8 August 1303 Crete and Dodecanese Islands earthquake resulting in destructive inundation in the Eastern Mediterranean. Initial evaluation of the exercise indicates that all CTWPs successfully participated in the exercise, where existing operational and some future prototype systems were utilized. System end-users (NTWC/TWFP/CPA) benefited from the exercise considerably, demonstrating the first successful test

  11. Evidence of Northeastern Atlantic Ocean Acidification Recorded by Boron Isotopes on Deep-sea Coral Madrepora oculata

    NASA Astrophysics Data System (ADS)

    Gonzalez-Roubaud, C.; Douville, E.; Bordier, L.; Louvat, P.; Gaillardet, J.; Hall-Spencer, J. M.; Juillet-Leclerc, A.

    2011-12-01

    measurements of carbon and oxygen isotopes, as well as the comparison of boron variability with other physiological parameters such as coral density, will allow us to confirm the drop on seawater pH on the last decades for the northeastern intermediate Atlantic waters.

  12. Preliminary observation on sexual maturity of black anglerfish (Lophius budegassa) in north-eastern Atlantic waters

    NASA Astrophysics Data System (ADS)

    Landa, Jorge; Antolínez, Ana; Ámez, Marco A.; Barrado, Joaquín; Castro, Begoña; Cañás, Lucía; Autón, Urbano; Fariña, Antonio C.; Hernández, Carmen

    2014-08-01

    The reproduction of black anglerfish (Lophius budegassa) was studied from samples collected during 5 years, from January 2006 to December 2010, in Celtic Sea, West and South of Ireland (ICES Div. VIIb-k) and Northern Spanish Atlantic waters (ICES Div. VIIIc-IXa). A total of 1167 specimens (4-99 cm) were sampled. The sex ratio, the spawning period and the maturity ogives by length were studied. The sex ratio in both areas studied varied with length, and it was close to 1:1 (male:female), 1:1.22 (54.90% of females) in Div. VIIb-k, and 1:1.01 (50.30% of females) in Div. VIIIc-IXa. A seasonal variation in sex ratio by length was observed at first time in Div VIIIc-IXa, with a very low proportion of intermediate sized females (40-60 cm) in the second semester. A seasonal reproductive migratory behavior is discussed. The spawning period was between December and July in Div. VIIIc-IXa. Spawning males were found throughout the year, but fewer spawning females, as in previous studies. The L50 values were estimated in Div. VIIIc-IXa: 38.2 cm for combined sexes, 36.0 cm for males and 53.0 cm for females. These values of sex ratio and L50 are similar to those obtained in closed areas studied.

  13. Taxonomic and functional profiles of soil samples from Atlantic forest and Caatinga biomes in northeastern Brazil

    PubMed Central

    Pacchioni, Ralfo G; Carvalho, Fabíola M; Thompson, Claudia E; Faustino, André L F; Nicolini, Fernanda; Pereira, Tatiana S; Silva, Rita C B; Cantão, Mauricio E; Gerber, Alexandra; Vasconcelos, Ana T R; Agnez-Lima, Lucymara F

    2014-01-01

    Although microorganisms play crucial roles in ecosystems, metagenomic analyses of soil samples are quite scarce, especially in the Southern Hemisphere. In this work, the microbial diversity of soil samples from an Atlantic Forest and Caatinga was analyzed using a metagenomic approach. Proteobacteria and Actinobacteria were the dominant phyla in both samples. Among which, a significant proportion of stress-resistant bacteria associated to organic matter degradation was found. Sequences related to metabolism of amino acids, nitrogen, and DNA and stress resistance were more frequent in Caatinga soil, while the forest sample showed the highest occurrence of hits annotated in phosphorous metabolism, defense mechanisms, and aromatic compound degradation subsystems. The principal component analysis (PCA) showed that our samples are close to the desert metagenomes in relation to taxonomy, but are more similar to rhizosphere microbiota in relation to the functional profiles. The data indicate that soil characteristics affect the taxonomic and functional distribution; these characteristics include low nutrient content, high drainage (both are sandy soils), vegetation, and exposure to stress. In both samples, a rapid turnover of organic matter with low greenhouse gas emission was suggested by the functional profiles obtained, reinforcing the importance of preserving natural areas. PMID:24706600

  14. Improving estimates of surface water radiocarbon reservoir ages in the northeastern Atlantic Ocean.

    NASA Astrophysics Data System (ADS)

    Greenop, Rosanna; Burke, Andrea; Rae, James; Austin, William; Reimer, Paula; Blaauw, Maarten; Crocker, Anya; Chalk, Thomas; Barker, Stephen; Knutz, Paul; Hall, Ian

    2016-04-01

    Radiocarbon measurements from foraminifera in marine sediment cores are widely used to constrain age models and the timing of paleoceanographic events, as well as past changes in ocean circulation and carbon cycling. However, the use of radiocarbon for both dating and palaeoceanographic applications is limited in sediment cores by a lack of knowledge about the surface ocean radiocarbon reservoir age and how it varies in both space and time. Typically, to convert a planktic radiocarbon age into a calendar age, an assumed constant reservoir age is applied. However, there is mounting evidence to suggest that this assumption of constant reservoir age through time is an oversimplification, particularly for the high latitude oceans during the cold climates of the last glacial and deglacial periods. Here we present new high-resolution radiocarbon records together with tephra tie points and 230-thorium (230Th) constrained sedimentation rates to improve estimates of radiocarbon reservoir age in the Northeast Atlantic Ocean. In addition we will explore the impact of the new reservoir ages for both the age models of the cores studied, as well as the palaeoceanographic implications of these reservoir age changes during intervals of rapid climate change over the past 40,000 years.

  15. Taxonomic and functional profiles of soil samples from Atlantic forest and Caatinga biomes in northeastern Brazil.

    PubMed

    Pacchioni, Ralfo G; Carvalho, Fabíola M; Thompson, Claudia E; Faustino, André L F; Nicolini, Fernanda; Pereira, Tatiana S; Silva, Rita C B; Cantão, Mauricio E; Gerber, Alexandra; Vasconcelos, Ana T R; Agnez-Lima, Lucymara F

    2014-06-01

    Although microorganisms play crucial roles in ecosystems, metagenomic analyses of soil samples are quite scarce, especially in the Southern Hemisphere. In this work, the microbial diversity of soil samples from an Atlantic Forest and Caatinga was analyzed using a metagenomic approach. Proteobacteria and Actinobacteria were the dominant phyla in both samples. Among which, a significant proportion of stress-resistant bacteria associated to organic matter degradation was found. Sequences related to metabolism of amino acids, nitrogen, and DNA and stress resistance were more frequent in Caatinga soil, while the forest sample showed the highest occurrence of hits annotated in phosphorous metabolism, defense mechanisms, and aromatic compound degradation subsystems. The principal component analysis (PCA) showed that our samples are close to the desert metagenomes in relation to taxonomy, but are more similar to rhizosphere microbiota in relation to the functional profiles. The data indicate that soil characteristics affect the taxonomic and functional distribution; these characteristics include low nutrient content, high drainage (both are sandy soils), vegetation, and exposure to stress. In both samples, a rapid turnover of organic matter with low greenhouse gas emission was suggested by the functional profiles obtained, reinforcing the importance of preserving natural areas. PMID:24706600

  16. Depth variation of bacterial extracellular enzyme activity and population diversity in the northeastern North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Davey, Katherine E.; Kirby, Richard R.; Turley, Carol M.; Weightman, Andrew J.; Fry, John C.

    Distinct profiles of extracellular proteolytic enzyme activity were observed in the water column of the North Atlantic, with maximum potential proteolytic activity occurring in the top 35 m. The proteolytic enzyme Vmax values varied significantly and decreased from 1.46 nM min -1 in surface waters to 0.365 nM min -1 at 100 m. In contrast, Km values increased with depth from about 70 to 360 μM. Cell-associated enzymes accounted for the majority of the observed proteolytic activity. Dissolved enzymes comprised only 30-40% of the total extracellular enzyme activity and exhibited a low substrate affinity ( Km=˜1000 μM). These observations indicate clear stratification of bacterial associated extracellular enzyme activity, with the maximum activity in surface waters. This is consistent with some environmental changes in the water column, especially algal biomass and nitrate concentration. Bacterial mediated nitrogen remineralization in surface waters was approximately three times the total nitrogen demand of phytoplankton and bacteria. We determined bacterial population diversity using 16S rRNA sequence analysis and found evidence for stratification, with a higher representation of the Cytophaga/Flexibacter/Bacteriodes group at 5 m compared to 100 m. No similar stratification was observed among the α-proteobacterial SAR11 cluster, which were especially prevalent in the PRIME eddy. However, sequences phylogenetically related to another marine cluster, SAR122, were only observed at 100 m. We suggest that stratification of proteolytic activity within the water column may be explained at least in part, by differences in the composition of the bacterial community.

  17. Early human settlements in Northern Africa: paleomagnetic evidence from the Ain Hanech Formation (northeastern Algeria)

    NASA Astrophysics Data System (ADS)

    Parés, J. M.; Sahnouni, M.; Van der Made, J.; Pérez-González, A.; Harichane, Z.; Derradji, A.; Medig, M.

    2014-09-01

    The question of the earliest hominid settlements in northern Africa has been under debate for a number of years due to the lack of precise chronologies. Here we present new paleomagnetic data that supports an Olduvai Subchron age for the archaeological sites at Ain Hanech and El-Kherba, in northern Algeria. Our study is based on a 22 m-thick magnetostratigraphy of the Ain Hanech Formation, which includes contextualized Oldowan and Acheulian lithic tools. Characteristic remanent magnetization directions were obtained from both thermal and alternating field demagnetization procedures of specimens from twenty five sampled horizons. Our results reveal the presence of the Olduvai Subchron in the upper part of the stratigraphic section, constraining the age of these important archaeological sites in northern Africa.

  18. Northeastern Atlantic benthic foraminifera during the last 45,000 years: Changes in productivity seen from the bottom up

    NASA Astrophysics Data System (ADS)

    Thomas, E.; Booth, L.; Maslin, M.; Shackleton, N. J.

    1995-06-01

    . High relative abundances of these species have been interpreted as indicative either of sluggish deep water circulation or of high organic carbon fluxes to the seafloor. In our cores, relative abundances of these species are negatively correlated with benthic foraminiferal accumulation rates, and we can thus not interpret them as indicative of increased productivity during glacials. The percentage of these "low oxygen" species calculated on a "phytodetritus species"—free basis decreased slightly at deglaciation at 5K, but not at 14K. This suggests that decreased production of North Atlantic Deep Water during the last glacial might have slightly affected benthic foraminiferal faunas in the eastern North Atlantic at 3547 m depth, but not at 1756 m. In conclusion, major changes in deep-sea benthic foraminiferal faunas over the last 45,000 years in our cores from the northeastern Atlantic were the result of changes in surface water productivity, not of changes in deep water circulation; productivity was lower during the glacial, probably because of extensive ice cover.

  19. Post-rift unroofing of the NW Africa passive continental margin during the Central Atlantic opening

    NASA Astrophysics Data System (ADS)

    Ghorbal, B.; Bertotti, G.; Andriessen, P. A. M.

    2009-04-01

    Many passive margins considered as being stable for long times, show however late uplift and exhumation at regional scale as assessed by low temperature geochronometry. A large amount of Lower Cretaceous terrigeneous sediments laid down in most of basins along the NW Africa continental margins indicate that a major episode of erosion occurred during early post-rift period in the Central Atlantic. AFT and (U-Th)/He dating performed, along a roughly >500 km N-S transect, on pre-Mesozoic basement rocks from Western Meseta to the Anti-Atlas (Morocco, NW Africa) document a fully unexpected widespread unroofing during the Middle-Late Jurassic to early Late Cretaceous, with AFT and (U-Th)/He ages ranging respectively between 120-170Ma and 115-165Ma. A well documented age cluster of 140±20Ma measured for the Moroccan Meseta, Atlas domains and Anti-Atlas belt designates those domains as potentially being the source areas of the detritic sediments considering the proximity of the depositional basins. Absence of major fault separating the Anti-Atlas from the rest of the Western African Craton during the Mesozoic suggests the unroofing region to extend further in Morocco, as far south as the Reguibat (Mauritania) or even New Guinea, documented by our investigation, and perhaps even further when confirmed by additional AFT and AHe data.

  20. 76 FR 36511 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-22

    ... United States; Atlantic Deep-Sea Red Crab; Amendment 3 AGENCY: National Marine Fisheries Service (NMFS... Fishery Management Council (Council) has submitted Amendment 3 to the Atlantic Deep-Sea Red Crab...

  1. A GCM Study of Responses of the Atmospheric Water Cycle of West Africa and the Atlantic to Saharan Dust Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Lau, K. M.; Kim, K. M.; Sud, Y. C.; Walker, G. K.

    2009-01-01

    The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summerr, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are ehanIed over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer overr the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at0

  2. Swim speed, behavior, and movement of North Atlantic right whales (Eubalaena glacialis) in coastal waters of northeastern Florida, USA.

    PubMed

    Hain, James H W; Hampp, Joy D; McKenney, Sheila A; Albert, Julie A; Kenney, Robert D

    2013-01-01

    In a portion of the coastal waters of northeastern Florida, North Atlantic right whales (Eubalaena glacialis) occur close to shore from December through March. These waters are included within the designated critical habitat for right whales. Data on swim speed, behavior, and direction of movement--with photo-identification of individual whales--were gathered by a volunteer sighting network working alongside experienced scientists and supplemented by aerial observations. In seven years (2001-2007), 109 tracking periods or "follows" were conducted on right whales during 600 hours of observation from shore-based observers. The whales were categorized as mother-calf pairs, singles and non-mother-calf pairs, and groups of 3 or more individuals. Sample size and amount of information obtained was largest for mother-calf pairs. Swim speeds varied within and across observation periods, individuals, and categories. One category, singles and non mother-calf pairs, was significantly different from the other two--and had the largest variability and the fastest swim speeds. Median swim speed for all categories was 1.3 km/h (0.7 kn), with examples that suggest swim speeds differ between within-habitat movement and migration-mode travel. Within-habitat right whales often travel back-and-forth in a north-south, along-coast, direction, which may cause an individual to pass by a given point on several occasions, potentially increasing anthropogenic risk exposure (e.g., vessel collision, fishing gear entanglement, harassment). At times, mothers and calves engaged in lengthy stationary periods (up to 7.5 h) that included rest, nursing, and play. These mother-calf interactions have implications for communication, learning, and survival. Overall, these behaviors are relevant to population status, distribution, calving success, correlation to environmental parameters, survey efficacy, and human-impacts mitigation. These observations contribute important parameters to conservation biology

  3. Swim Speed, Behavior, and Movement of North Atlantic Right Whales (Eubalaena glacialis) in Coastal Waters of Northeastern Florida, USA

    PubMed Central

    Hain, James H. W.; Hampp, Joy D.; McKenney, Sheila A.; Albert, Julie A.; Kenney, Robert D.

    2013-01-01

    In a portion of the coastal waters of northeastern Florida, North Atlantic right whales (Eubalaena glacialis) occur close to shore from December through March. These waters are included within the designated critical habitat for right whales. Data on swim speed, behavior, and direction of movement – with photo-identification of individual whales – were gathered by a volunteer sighting network working alongside experienced scientists and supplemented by aerial observations. In seven years (2001–2007), 109 tracking periods or “follows” were conducted on right whales during 600 hours of observation from shore-based observers. The whales were categorized as mother-calf pairs, singles and non-mother-calf pairs, and groups of 3 or more individuals. Sample size and amount of information obtained was largest for mother-calf pairs. Swim speeds varied within and across observation periods, individuals, and categories. One category, singles and non mother-calf pairs, was significantly different from the other two – and had the largest variability and the fastest swim speeds. Median swim speed for all categories was 1.3 km/h (0.7 kn), with examples that suggest swim speeds differ between within-habitat movement and migration-mode travel. Within-habitat right whales often travel back-and-forth in a north-south, along-coast, direction, which may cause an individual to pass by a given point on several occasions, potentially increasing anthropogenic risk exposure (e.g., vessel collision, fishing gear entanglement, harassment). At times, mothers and calves engaged in lengthy stationary periods (up to 7.5 h) that included rest, nursing, and play. These mother-calf interactions have implications for communication, learning, and survival. Overall, these behaviors are relevant to population status, distribution, calving success, correlation to environmental parameters, survey efficacy, and human-impacts mitigation. These observations contribute important parameters to

  4. Chemical Characteristics of Continental Outflow Over the Tropical South Atlantic Ocean from Brazil and Africa

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Bradshaw, J. D.; Sandholm, S. T.; Smyth, S.; Blake, D. R.; Blake, N. R.; Sachse, G. W.; Collins, J. E.; Heikes, B. G.; Anderson, B. E.; Gregory, G. L.; Singh, H. B.; Lefer, B. L.; Bachmeier, A. S.

    1996-01-01

    The chemical characteristics of air parcels over the tropical South Atlantic during September - October 1992 are summarized by analysis of aged marine and continental outflow classifications. Positive correlations between CO and CH3CL and minimal enhancements of C2CL40, and various ChloroFluoroCarbon (CFC) species in air parcels recently advected over the South Atlantic basin strongly suggest an impact on tropospheric chemistry from biomass burning on adjacent continental areas of Brazil and Africa. Comparison of the composition of aged Pacific air with aged marine air over the South Atlantic basin from 0.3 to 12.5 km altitude indicates potential accumulation of long-lived species during the local dry season. This may amount to enhancements of up to two-fold for C2H6, 30% for CO, and 10% for CH3Cl. Nitric oxide and NO(x) were significantly enhanced (up to approx. 1 part per billion by volume (ppbv)) above 10 km altitude and poorly correlated with CO and CH3Cl. In addition, median mixing ratios of NO and NO(x) were essentially identical in aged marine and continental outflow air masses. It appears that in addition to biomass burning, lightning or recycled reactive nitrogen may be an important source of NO(x) to the upper troposphere. Methane exhibited a monotonic increase with altitude from approx. 1690 to 1720 ppbv in both aged marine and continental outflow air masses. The largest mixing ratios in the upper troposphere were often anticorrelated with CO, CH3Cl, and CO2, suggesting CH, contributions from natural sources. We also argue, based on CH4/CO ratios and relationships with various hydrocarbon and CFC species, that inputs from biomass burning and the northern hemisphere are unlikely to be the dominant sources of CO, CH4 and C2H6 in aged marine air. Emissions from urban areas would seem to be necessary to account for the distribution of at least CH4 and C2H6. Over the African and South American continents an efficient mechanism of convective vertical transport

  5. Micropulse lidar observations of tropospheric aerosols over northeastern South Africa during the ARREX and SAFARI 2000 dry season experiments

    NASA Astrophysics Data System (ADS)

    Campbell, James R.; Welton, Ellsworth J.; Spinhirne, James D.; Ji, Qiang; Tsay, Si-Chee; Piketh, Stuart J.; Barenbrug, Marguerite; Holben, Brent N.

    2003-07-01

    During the Aerosol Recirculation and Rainfall Experiment (ARREX 1999) and Southern African Regional Science Initiative (SAFARI 2000) dry season experiments, a micropulse lidar (523 nm) instrument was operated at the Skukuza Airport in northeastern South Africa. The lidar was colocated with a diverse array of passive radiometric equipment. For SAFARI 2000, a daytime time series of layer mean aerosol optical properties, including layer mean extinction-to-backscatter ratios and vertical extinction cross-section profiles are derived from the synthesis of the lidar data and aerosol optical depths from available AERONET Sun photometer data. Combined with derived spectral Angstrom exponents, normalized broadband flux measurements, and calculated air mass back-trajectories, the temporal evolution of the surface aerosol layer optical properties is analyzed for climatological trends. For dense biomass smoke events the extinction-to-backscatter ratio is between 50 and 90 sr, and corresponding spectral Angstrom exponent values are between 1.50 and 2.00. Observations of an advecting smoke event during SAFARI 2000 are shown. The smoke was embedded within two distinct stratified thermodynamic layers causing the particulate mass to advect over the instrument array in an incoherent manner on the afternoon of 1 September 2000. Significant surface broadband flux forcing of over -50 W/m2 was measured in this event. The evolution of the vertical aerosol extinction profile is profiled using the lidar data. Finally, observations of persistent elevated aerosol layers during ARREX 1999 are presented and discussed. Back-trajectory analyses combined with lidar and Sun photometer measurements indicate the likelihood for these aerosols being the result of long-range particulate transport from the southern and central South America.

  6. Phylogenetic relationships elucidate colonization patterns in the intertidal grazers Osilinus Philippi, 1847 and Phorcus Risso, 1826 (Gastropoda: Trochidae) in the northeastern Atlantic Ocean and Mediterranean Sea.

    PubMed

    Donald, Kirsten M; Preston, Joanne; Williams, Suzanne T; Reid, David G; Winter, David; Alvarez, Raquel; Buge, Barbara; Hawkins, Stephen J; Templado, Jose; Spencer, Hamish G

    2012-01-01

    Snails in the closely related trochid genera Phorcus Risso, 1826 and Osilinus Philippi, 1847 are ecologically important algal grazers in the intertidal zone of the northeastern Atlantic Ocean and Mediterranean Sea. Here we present the first complete molecular phylogeny for these genera, based on the nuclear 28S rRNA gene and the mitochondrial 16S rRNA and COI genes, and show that the current classification is erroneous. We recognize nine species in a single genus, Phorcus: estimated by BEAST analysis, this arose 30 (± 10) Ma; it consists of two subgenera, Phorcus and Osilinus, which we estimate diverged 14 (± 4.5) Ma. Osilinus kotschyi, from the Arabian and Red Seas, is not closely related and is tentatively referred to Priotrochus Fischer, 1879. Our phylogeny allows us to address biogeographical questions concerning the origins of the Mediterranean and Macaronesian species of this group. The former appear to have evolved from Atlantic ancestors that invaded the Mediterranean on several occasions after the Zanclean Flood, which ended the Messinian Salinity Crisis 5.3 Ma; whereas the latter arose from several colonizations of mainland Atlantic ancestors within the last 3 (± 1.5) Ma. PMID:21945534

  7. An Archeomagnetic Record From Southern Africa and its Bearing on the History of the South Atlantic Anomaly

    NASA Astrophysics Data System (ADS)

    Grigsby, M. R.; Tarduno, J. A.; Cottrell, R. D.; Huffman, T. N.; Watkeys, M. K.; Blackman, E.

    2015-12-01

    The low intensity area in Earth's recent magnetic field that spans the southern Atlantic Ocean, Africa and South America is commonly called the South Atlantic Anomaly (SAA). Many believe the SAA is linked to the dramatic decay of the dipole geomagnetic field intensity during the last 160 years, and the growth of a reversed core flux patch beneath South Africa. The dipole field decay has even motivated speculation that Earth is heading toward a geomagnetic field reversal. But understanding these phenomena within the context of longer-term geomagnetic history has been limited by a lack of Southern Hemisphere archeomagnetic data. We have recently presented the first archeomagnetic data from Iron Age sites of southern Africa (~1000-1650 AD) (Tarduno et al., 2014, 2015). Magnetic data show a sharp intensity drop at ~1300 AD, at a rate comparable to modern field changes in the SAA, (but to lower values). These changes motivated our conceptual model whereby the recurrence of low field values reflects magnetic flux expulsion from the core, promoted by the unusual core-mantle boundary composition and structure beneath southern Africa defined by seismology (specifically the African Large Low Velocity Seismic Province, or LLVSP). Because the African LLVSP is a longstanding structure, we expect this region to be a steady site of flux expulsion, and perhaps the triggering site for reversals, on time scales of millions of years. Here we discuss our ongoing efforts to extend the archeomagnetic record from southern Africa back in time, and further develop the flux expulsion- African LLVSP hypothesis, through new sampling and paleomagnetic analyses of Iron Age burnt huts, grain bins and kraals from South Africa, Zimbabwe and Botswana.

  8. Genetic divergence between Atlantic and Indo-Pacific stocks of bigeye tuna (Thunnus obesus) and admixture around South Africa.

    PubMed

    Chow, S; Okamoto, H; Miyabe, N; Hiramatsu, K; Barut, N

    2000-02-01

    Two mitochondrial DNA segments of the bigeye tuna (Thunnus obesus) were amplified by polymerase chain reaction (PCR), and restriction fragment length polymorphism (RFLP) analyses of these segments were used for the genetic stock study. The variation in a segment flanking the ATPase and COIII genes was low; only two genotypes (alpha and beta) were detected by RsaI digestion. Yet a large difference in the genotype distribution was observed between ocean basin samples. The alpha type predominated in four Atlantic samples, where 178 of 244 individuals were the alpha type. In contrast, only one of 195 individuals collected in the Indo-Pacific was the alpha type? The frequency of the alpha type varied considerably from 0 to 80% among seven samples collected off the Cape of Good Hope. The variation found in the other segment, containing the D-loop region, was much higher; two endonucleases (DpnII and RsaI) detected five genotypes each and 15 composite genotypes. A highly significant difference in genotype frequencies was observed between the Atlantic and Indo-Pacific samples, but no heterogeneity was observed among the four Atlantic or among four Indo-Pacific samples. These results clearly indicate that not only gene flow, but also fish migration, between the Atlantic and Indian Oceans are severely restricted, and that fishes from these distinct stocks are intermingling around South Africa. The simple and diagnostic genetic marker found in this study can be used to estimate mixing ratios between Atlantic and Indian stocks around South Africa. PMID:10672166

  9. An archeomagnetic record from southern Africa and its bearing on the history of the South Atlantic Anomaly

    NASA Astrophysics Data System (ADS)

    Tarduno, John; Cottrell, Rory; Huffman, Thomas; Watkeys, Michael; Grigsby, Miriam; Blackman, Eric

    2016-04-01

    The paucity of Southern Hemisphere archeomagnetic data limits the resolution of paleosecular variation models, while at the same time important changes in the modern and historical field, including the recent dipole decay, appear to originate in this region. We have recently presented the first archeomagnetic data from Iron Age sites of southern Africa (˜1000-1650 AD) (Tarduno et al., Nature Communications, 2015). Magnetic data show a sharp intensity drop at ˜1300 AD, at a rate comparable to modern field changes in the South Atlantic Anomaly (SAA), but to lower values. These changes motivated our conceptual model whereby the recurrence of low field values reflects magnetic flux expulsion from the core, promoted by the unusual core-mantle boundary composition and structure beneath southern Africa as defined by seismology (specifically the African Large Low Velocity Seismic Province, or LLVSP). Because the African LLVSP is a longstanding structure, we expect this region to be a steady site of flux expulsion, and perhaps the triggering site for reversals, on time scales of millions of years. Here we discuss our ongoing efforts to extend the archeomagnetic record from southern Africa back in time, and further develop the flux expulsion- African LLVSP hypothesis, through new sampling and paleomagnetic analyses of Iron Age burnt huts, grain bins and kraals from South Africa, Zimbabwe and Botswana. Our preliminary analyses define a loop in the archeomagnetic curve for southern Africa between ca. 400 and 1000 AD, absent in predictions from available paleosecular variation models, that might record another flux expulsion episode.

  10. Measurements of the stable carbon isotope composition of dissolved inorganic carbon in the Northeastern Atlantic and Nordic Seas during summer 2012

    NASA Astrophysics Data System (ADS)

    Humphreys, M. P.; Achterberg, E. P.; Griffiths, A. M.; McDonald, A.; Boyce, A. J.

    2015-01-01

    The stable carbon isotope composition of dissolved inorganic carbon (δ13CDIC) in seawater was measured in samples collected during two cruises in the Northeastern Atlantic and Nordic Seas from June to August 2012. One cruise was part of the UK Ocean Acidification research programme, and the other was a repeat hydrographic transect of the Extended Ellett Line. In combination with measurements made of various other variables on these and other cruises, these data can be used to constrain the anthropogenic component of DIC in the interior ocean, and also assist in determining the influence of biological carbon uptake on surface ocean carbonate chemistry. The measurements have been processed, quality-controlled and submitted to an in-preparation global compilation of seawater δ13CDIC data, and are available from the British Oceanographic Data Centre. The observed δ13CDIC values fall in a range from -0.58 to +2.37‰, relative to the Vienna Peedee Belemnite standard. From duplicate samples collected during both cruises, the precision for the 552 results is 0.07‰, which is similar to other published studies of this kind. Data doi:10.5285/09760a3a-c2b5-250b-e053-6c86abc037c0 (Northeastern Atlantic), doi:10.5285/09511dd0-51db-0e21-e053-6c86abc09b95 (Nordic Seas).

  11. New Perspectives from Satellite and Profile Observations on Tropospheric Ozone over Africa and the Adjacent Oceans: An Indian-Atlantic Ocean Link to tbe "Ozone Paradox"

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Witte, Jacquelyn C.; Diab, Roseanne D.; Thouret, Valerie; Sauvage, Bastien; Chatfield, B.; Guan, Hong

    2004-01-01

    In the past few years, tropospheric ozone observations of Africa and its adjacent ocenas have been greatly enhanced by high resolution (spatial and temporal) satellite measurements and profile data from aircraft (MOZAIC) and balloon-borne (SHADOZ) soundings. These views have demonstrated for the first time the complexity of chemical-dynamical interactions over the African continent and the Indian and Atlantic Oceans. The tropical Atlantic "ozone paradax" refers to the observation that during the season of maximum biomass burning in west Africa north of the Intertropical Convergence Zone (ITCZ), the highest tropospheric ozone total column occurs south of the ITCZ over the tropical Atlantic. The longitudinal view of tropospheric ozone in the southern tropics from SHADOZ (Southern Hemisphere Additional Ozonesondes) soundings shown the persistence of a "zonal-wave one" pattern that reinforces the "ozone paradox". These ozone features interact with dynamics over southern and northern Africa where anthropogenic sources include the industrial regions of the South African Highveld and Mideastern-Mediterranean influences, respectively. Our newest studies with satellites and soundings show that up to half the ozone pollution over the Atlantic in the January-March "paradox" period may originate from south Asian pollution. Individual patches of pollurion over the Indian Ocean are transported upward by convective mixing and are enriched by pyrogenic, biogenic sources and lightning as they cross Africa and descend over the Atlantic. In summary, local sources, intercontinental import and export and unique regional transport patterns put Africa at a crossroads of troposheric ozone influences.

  12. Brazil-Africa geological links

    NASA Astrophysics Data System (ADS)

    Torquato, Joaquim Raul; Cordani, Umberto G.

    1981-04-01

    In this work, the main evidence and conclusions regarding geological links between Brazil and Africa are summarized, with emphasis on the geochronological aspects. Taking into account the geographical position, as well as the similarities in the geochronological pattern, the following main provinces of the two continents are correlated: The Imataca and Falawatra complexes in the Guayana Shield and the Liberian Province of West Africa. The Paraguay-Araguaia and the Rockelide Fold Belts. The Sa˜o Luiz and the West African cratonic areas. The Caririan Fold Belt of northeastern Brazil and the Pan-Africa Belt of Nigeria and Cameroon. The JequiéComplex of Bahia, the Ntem Complex of Cameroon and similar rocks of Gabon and Angola. The Ribeira Fold Belt in Brazil and the West Congo and Damara Belts in West and South Africa. In addition, other geological links are considered, such as some of the major linear fault zones which can be traced across the margins of South America and Africa, in the pre-drift reconstructions. Correlations are also made of the tectonic and stratigraphic evolution of the Paranáand Karroo syneclises, and the Brazilian and African marginal basins around the South Atlantic, during their initial stages. Finally, several similarities in the tectonic evolution of South America and Africa, during and after the onset of drifting, are shown to be compatible with a recent origin for the South Atlantic floor, as required by sea-floor spreading and continental drift between South America and Africa.

  13. Dictyoceratida (Porifera: Demospongiae) from Tropical Southwestern Atlantic (Northeastern Brazil, Sergipe State) and the description of three new species.

    PubMed

    Sandes, Joana; Pinheiro, Ulisses

    2014-01-01

    Five species of dictyoceratid sponges were collected from trawling on the continental shelf of Sergipe State, Northeastern Brazil, of which three are new to science: Ircinia sergipana sp. nov., Ircinia repens sp. nov., Ircinia strobilina, Hyattella cavernosa and Smenospongia ramosa sp. nov., the latter the first record of the genus Smenospongia from Brazil.  PMID:25081789

  14. Genetic Diversity of White Sharks, Carcharodon carcharias, in the Northwest Atlantic and Southern Africa.

    PubMed

    O'Leary, Shannon J; Feldheim, Kevin A; Fields, Andrew T; Natanson, Lisa J; Wintner, Sabine; Hussey, Nigel; Shivji, Mahmood S; Chapman, Demian D

    2015-01-01

    The white shark, Carcharodon carcharias, is both one of the largest apex predators in the world and among the most heavily protected marine fish. Population genetic diversity is in part shaped by recent demographic history and can thus provide information complementary to more traditional population assessments, which are difficult to obtain for white sharks and have at times been controversial. Here, we use the mitochondrial control region and 14 nuclear-encoded microsatellite loci to assess white shark genetic diversity in 2 regions: the Northwest Atlantic (NWA, N = 35) and southern Africa (SA, N = 131). We find that these 2 regions harbor genetically distinct white shark populations (Φ ST = 0.10, P < 0.00001; microsatellite F ST = 0.1057, P < 0.021). M-ratios were low and indicative of a genetic bottleneck in the NWA (M-ratio = 0.71, P < 0.004) but not SA (M-ratio = 0.85, P = 0.39). This is consistent with other evidence showing a steep population decline occurring in the mid to late 20th century in the NWA, whereas the SA population appears to have been relatively stable. Estimates of effective population size ranged from 22.6 to 66.3 (NWA) and 188 to 1998.3 (SA) and evidence of inbreeding was found (primarily in NWA). Overall, our findings indicate that white population dynamics within NWA and SA are determined more by intrinsic reproduction than immigration and there is genetic evidence of a population decline in the NWA, further justifying the strong domestic protective measures that have been taken for this species in this region. Our study also highlights how assessment of genetic diversity can complement other sources of information to better understand the status of threatened marine fish populations. PMID:25762777

  15. Richness and abundance of the cardini group of Drosophila (Diptera, Drosophilidae) in the Caatinga and Atlantic Forest biomes in northeastern Brazil.

    PubMed

    Rohde, Cláudia; Silva, Diva Maria Izabel O; Oliveira, Geórgia F; Monteiro, Liv S; Montes, Martín A; Garcia, Ana Cristina L

    2014-12-01

    Brazil has a high diversity of flies of the genus Drosophila, and part of this richness is represented by the cardini group. We analyzed the fluctuations in the richness and abundance of this group, in environments that had never previously been studied in the northeastern region of Brazil. Among the 28,204 drosophilids sampled, 1,294 belonged to the cardini group and were represented by D. polymorpha, D. cardini, D. neocardini and D. cardinoides. Occurrences of D. neocardini and D. cardinoides were registered for the first time in the Caatinga. In this biome, D. cardini stood out as having the highest abundance, and D. polymorpha was not observed. In the coastal Atlantic Forest, D. cardini was not registered, but D. polymorpha was found in all the localities investigated. Mangrove swamps were the environment with the lowest abundance and richness of the cardini group. The High-altitude Forest presented the highest richness of this group. We suggest that the high abundance of D. polymorpha in the High-altitude Forest and in the coastal Atlantic Forest may be a reflection of the historical relationship between these two environments. PMID:25590710

  16. Richness and abundance of the cardini group of Drosophila (Diptera, Drosophilidae) in the Caatinga and Atlantic Forest biomes in northeastern Brazil.

    PubMed

    Rohde, Cláudia; Silva, Diva Maria Izabel O; Oliveira, Geórgia F; Monteiro, Liv S; Montes, Martín A; Garcia, Ana Cristina L

    2014-11-11

    Brazil has a high diversity of flies of the genus Drosophila, and part of this richness is represented by the cardini group. We analyzed the fluctuations in the richness and abundance of this group, in environments that had never previously been studied in the northeastern region of Brazil. Among the 28,204 drosophilids sampled, 1,294 belonged to the cardini group and were represented by D. polymorpha, D. cardini, D. neocardini and D. cardinoides. Occurrences of D. neocardini and D. cardinoides were registered for the first time in the Caatinga. In this biome, D. cardini stood out as having the highest abundance, and D. polymorpha was not observed. In the coastal Atlantic Forest, D. cardini was not registered, but D. polymorpha was found in all the localities investigated. Mangrove swamps were the environment with the lowest abundance and richness of the cardini group. The High-altitude Forest presented the highest richness of this group. We suggest that the high abundance of D. polymorpha in the High-altitude Forest and in the coastal Atlantic Forest may be a reflection of the historical relationship between these two environments. PMID:25387390

  17. 76 FR 39369 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fishery; Amendment 3

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-06

    ...NMFS proposes regulations to implement Amendment 3 to the Atlantic Deep-Sea Red Crab Fishery Management Plan (Red Crab FMP). The New England Fishery Management Council (Council) developed Amendment 3 to bring the Red Crab FMP into compliance with the annual catch limit (ACL) and accountability measure (AM) requirements of the Magnuson- Stevens Fishery Conservation and Management Act......

  18. 76 FR 60379 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-29

    ... measures in Amendment 3 published in the Federal Register on July 6, 2011 (76 FR 39369), with public... Amendment 3 was published in the Federal Register on June 22, 2011 (76 FR 36511), with public comments... United States; Atlantic Deep-Sea Red Crab; Amendment 3 AGENCY: National Marine Fisheries Service...

  19. Measurements of the stable carbon isotope composition of dissolved inorganic carbon in the northeastern Atlantic and Nordic Seas during summer 2012

    NASA Astrophysics Data System (ADS)

    Humphreys, M. P.; Achterberg, E. P.; Griffiths, A. M.; McDonald, A.; Boyce, A. J.

    2015-06-01

    The stable carbon isotope composition of dissolved inorganic carbon (δ13CDIC) in seawater was measured in a batch process for 552 samples collected during two cruises in the northeastern Atlantic and Nordic Seas from June to August 2012. One cruise was part of the UK Ocean Acidification research programme, and the other was a repeat hydrographic transect of the Extended Ellett Line. In combination with measurements made of other variables on these and other cruises, these data can be used to constrain the anthropogenic component of dissolved inorganic carbon (DIC) in the interior ocean, and to help to determine the influence of biological carbon uptake on surface ocean carbonate chemistry. The measurements have been processed, quality-controlled and submitted to an in-preparation global compilation of seawater δ13CDIC data, and are available from the British Oceanographic Data Centre. The observed δ13CDIC values fall in a range from -0.58 to +2.37 ‰, relative to the Vienna Pee Dee Belemnite standard. The mean of the absolute differences between samples collected in duplicate in the same container type during both cruises and measured consecutively is 0.10 ‰, which corresponds to a 1σ uncertainty of 0.09 ‰, and which is within the range reported by other published studies of this kind. A crossover analysis was performed with nearby historical δ13CDIC data, indicating that any systematic offsets between our measurements and previously published results are negligible. Data doi:10.5285/09760a3a-c2b5-250b-e053-6c86abc037c0 (northeastern Atlantic), doi:10.5285/09511dd0-51db-0e21-e053-6c86abc09b95 (Nordic Seas).

  20. Atlantic Ocean modulated hydroclimate of the subtropical northeastern Mexico since the last glacial maximum and comparison with the southern US

    NASA Astrophysics Data System (ADS)

    Roy, Priyadarsi D.; Rivero-Navarrete, Axel; Sánchez-Zavala, José L.; Beramendi-Orosco, Laura E.; Muthu-Sankar, Gowrappan; Lozano-Santacruz, Rufino

    2016-01-01

    Proxy records generated from chemical composition and radiocarbon dating of a sediment sequence collected from the El Potosi Basin provide information about variable hydroclimate of the subtropical northeastern Mexico since the last glacial maximum (LGM). Minimal amounts of runoff and more carbonate deposition during >19 ka represent the LGM. The deglaciation was wetter compared to the LGM and enhanced runoff during ˜ 19- 12 ka transported more Ti-bearing clastics from a relatively humid watershed. Over the deglaciation, the basin received more runoff during the Bølling-Allerød compared to the Heinrich Stadial 1 and Younger Dryas. Reduction in the amount of runoff during ˜ 10- 1 ka and deposition of unweathered Si-bearing clastics during ˜ 4- 1 ka suggest that the Holocene was drier compared to the deglaciation. Hydroclimates of the northeastern Mexico and southern US were synchronous during the LGM as well as deglaciation. Change from the drier LGM to wetter Bølling-Allerød occurred as the Gulf of Mexico became warmer and the region received more summer precipitation. However, the dissimilarities observed in regional hydroclimates of the Holocene need further evaluation.

  1. Mineral ballast and particle settling rates in the coastal upwelling system off NW Africa and the South Atlantic

    NASA Astrophysics Data System (ADS)

    Fischer, G.; Karakas, G.; Blaas, M.; Ratmeyer, V.; Nowald, N.; Schlitzer, R.; Helmke, P.; Davenport, R.; Donner, B.; Neuer, S.; Wefer, G.

    2009-03-01

    The ocean off NW Africa is the second most important coastal upwelling system with a total annual primary production of 0.33 Gt of carbon per year (Carr in Deep Sea Res II 49:59-80, 2002). Deep ocean organic carbon fluxes measured by sediment traps are also fairly high despite low biogenic opal fluxes. Due to a low supply of dissolved silicate from subsurface waters, the ocean off NW Africa is characterized by predominantly carbonate-secreting primary producers, i.e. coccolithophorids. These algae which are key primary producers since millions of years are found in organic- and chlorophyll-rich zooplankton fecal pellets, which sink rapidly through the water column within a few days. Particle flux studies in the Mauretanian upwelling area (Cape Blanc) confirm the hypothesis of Armstrong et al. (Deep Sea Res II 49:219-236, 2002) who proposed that ballast availability, e.g. of carbonate particles, is essential to predict deep ocean organic carbon fluxes. The role of dust as ballast mineral for organic carbon, however, must be also taken into consideration in the coastal settings off NW Africa. There, high settling rates of larger particles approach 400 m day-1, which may be due to a particular composition of mineral ballast. An assessment of particle settling rates from opal-production systems in the Southern Ocean of the Atlantic Sector, in contrast, provides lower values, consistent with the assumptions of Francois et al. (Global Biogeochem Cycles 16(4):1087, 2002). Satellite chlorophyll distributions, particle distributions and fluxes in the water column off NW Africa as well as modelling studies suggest a significant lateral flux component and export of particles from coastal shelf waters into the open ocean. These transport processes have implications for paleo-reconstructions from sediment cores retrieved at continental margin settings.

  2. Source and Delivery of Nutrients to Receiving Waters in the Northeastern and Mid-Atlantic Regions of the United States1

    PubMed Central

    Moore, Richard B; Johnston, Craig M; Smith, Richard A; Milstead, Bryan

    2011-01-01

    Abstract This study investigates nutrient sources and transport to receiving waters, in order to provide spatially detailed information to aid water-resources managers concerned with eutrophication and nutrient management strategies. SPAtially Referenced Regressions On Watershed attributes (SPARROW) nutrient models were developed for the Northeastern and Mid-Atlantic (NE US) regions of the United States to represent source conditions for the year 2002. The model developed to examine the source and delivery of nitrogen to the estuaries of nine large rivers along the NE US Seaboard indicated that agricultural sources contribute the largest percentage (37%) of the total nitrogen load delivered to the estuaries. Point sources account for 28% while atmospheric deposition accounts for 20%. A second SPARROW model was used to examine the sources and delivery of phosphorus to lakes and reservoirs throughout the NE US. The greatest attenuation of phosphorus occurred in lakes that were large relative to the size of their watershed. Model results show that, within the NE US, aquatic decay of nutrients is quite limited on an annual basis and that we especially cannot rely on natural attenuation to remove nutrients within the larger rivers nor within lakes with large watersheds relative to the size of the lake. PMID:22457578

  3. Intracultural Variation in the Knowledge of Medicinal Plants in an Urban-Rural Community in the Atlantic Forest from Northeastern Brazil

    PubMed Central

    de Almeida, Cecília de Fátima Castelo Branco Rangel; Ramos, Marcelo Alves; Silva, Rafael Ricardo Vasconcelos; de Melo, Joabe Gomes; Medeiros, Maria Franco Trindade; Araújo, Thiago Antonio de Sousa; de Almeida, Alyson Luiz Santos; de Amorim, Elba Lúcia Cavalcanti; Alves, Rômulo Romeu da Nóbrega; de Albuquerque, Ulysses Paulino

    2012-01-01

    This study assessed the intracultural knowledge of the use of medicinal plants in an urban-rural community in an Atlantic forest fragment in northeastern Brazil. We examined the importance of native and exotic species and the effects of gender and age on that knowledge. We also compared data obtained from different groups of informants (local experts and general community). We conducted 194 interviews between June 2007 and January 2008, using the freelist technique and semistructured forms to collect ethnobotanical data. Information obtained from the community was compared with that from six local experts who participated in a survey in 2003. From a total of 209 ethnospecies, exotic and herbaceous plants presented higher richness. With respect to the number of citations, women and older informants were shown to know a higher number of medicinal plants. Comparing knowledge of local experts with that of the general community, we noted that experts know a similar wealth of plant families and therapeutic indications, but the community knows a greater species richness. These results indicate that local experts may provide useful information for studies that search for a quick diagnosis of the knowledge of a given community. PMID:22110546

  4. South Atlantic fits and intraplate boundaries in Africa and South America

    NASA Astrophysics Data System (ADS)

    Unternehr, P.; Curie, D.; Olivet, J. L.; Goslin, J.; Beuzart, P.

    1988-12-01

    The misfit problems raised by the pre-drift reconstructions of the South and Equatorial Atlantic compel us to resort to intraplate deformations. It is shown that acceptable deformations of the African plate in line with the Benue Trough and the Transafrican rifts and shear zones provide a far from satisfactory solution to the geometrical misfit problems in the South Atlantic. These problems can instead be alleviated by considering a degree of deformation of the South American plate along an intraplate boundary in line with the Parana Province, the Rio Grande Rise and the Walvis Ridge. In spite of the scarcity of field observations in this area of South America, we show that such a deformation cannot be ruled out, but it will have to be associated with deformations in the Equatorial Atlantic and in other areas of the African and South American plates.

  5. Discriminating dusts and dusts sources using magnetic properties and hematite:Goethite ratios of surface materials and dust from North Africa, the Atlantic and Barbados

    NASA Astrophysics Data System (ADS)

    Oldfield, F.; Chiverrell, R. C.; Lyons, R.; Williams, E.; Shen, Z.; Bristow, C.; Bloemendal, J.; Torrent, J.; Boyle, J. F.

    2014-06-01

    Magnetic measurements and Diffuse Reflectance Spectroscopy are used in an attempt to differentiate dusts and dust sources in North Africa, over the Atlantic and in Barbados. Special attention is paid to dusts and to lacustrine clay and diatomite samples from the Bodélé Depression, in view of its alleged importance in trans-Atlantic and global dust generation. The results indicate that dusts from the Bodélé Depression can be distinguished from other dusts and potential sources in Niger, Chad, Burkina and Mali on the basis of their magnetic properties, notably their low magnetic concentrations, negligible frequency dependent magnetic susceptibility and distinctive IRM demagnetization characteristics. Dust from over the Atlantic and from Barbados, obtained from meshes in the 1960s and ’70s have high frequency dependent susceptibility values, are quite distinctive from the Bodélé Depression samples and are more closely comparable to samples from elsewhere in the Sahara and especially the Sahel. The Diffuse Reflectance Spectroscopy data, though of limited value here, are not inconsistent with the inferences based on the magnetic measurements. Overall, the results obtained point to a wide range of sources for dusts both over North Africa itself and across the Atlantic. They do not offer support to the view that dusts from the Bodélé Depression have dominated supply across the Atlantic over the last five decades.

  6. Mapping the Spatial and Temporal Distribution of N and O Isotopes in Precipitation Nitrate Across the Northeastern and Mid-Atlantic United States

    NASA Astrophysics Data System (ADS)

    Elliott, E. M.; Kendall, C.; Harlin, K.; Butler, T.; Carlton, R.; Wankel, S.

    2004-12-01

    Atmospheric deposition of N is a universally important pathway by which ecosystems receive fixed, bioavailable N. Since the 1880s, atmospheric deposition of N has become increasingly important, as NOx emissions from fossil fuel combustion have steadily increased. In particular, the Northeastern and Mid-Atlantic U.S. receive some of the highest rates of nitrate wet deposition in the country, causing a cascade of detrimental effects. In order to effectively mediate the impacts of nitrate deposition, it is critical to understand the dynamics among NOx sources, atmospheric chemical transformations and transport, and the characteristics of the nitrate that is ultimately deposited. To address this need, this research takes advantage of recent methodological improvements, coupled with national networks (NADP, AIRMoN) of archived precipitation, to characterize N and O isotopic composition of nitrate in precipitation across the Northeastern and Mid-Atlantic U.S. We investigate the critical question of whether variations in \\delta15N and \\delta18O of nitrate wet deposition are mainly a function of atmospheric processes (e.g., seasonal variations in reaction pathways) or variable NOx source contributions (e.g., power plant emissions, vehicle exhaust). Spatial and seasonal variability of \\delta15N and \\delta18O is investigated using bimonthly archived samples from 2000. Furthermore, a high resolution record of daily precipitation from a single site is used to highlight within-season isotopic variability. Potential correlations between isotopic values and major NOx sources are explored using EPA datasets for monthly county-level emissions from two major NOx sources, electric generating units and on-road vehicles. Analysis of samples for \\Delta17O is in progress. A key concern regarding analysis of archived samples is nitrate preservation. We tested the stability of nitrate concentrations, and hence potential isotopic fractionations, by reanalyzing filtered, refrigerated

  7. Upper Intermediate Water Reservoir Ages in the Northeastern Atlantic During the Past 11000 Years: New Evidence for Mid Holocene Freshening of the North Atlantic

    NASA Astrophysics Data System (ADS)

    Frank, N.; Paterne, M.; Blamart, D.; Colin, C.; Tisnerat-Laborde, N.; van Weering, T.; Henriet, J.

    2006-12-01

    Deep-water corals such as Lophelia pertusa and Madrepora occulata construct reef like structures along the slopes of Rockall Trough and within the Porcupine Seabight between 500 and 1000m depth, so called carbonate mounds. The hydrography is complex, with upper intermediate and surface water originating in the temperate North Atlantic and water masses from the sub-polar gyre and Labrador Sea circulating at depth within the Rockall Trough. Moreover, Norwegian Sea deep-water returns southward over the sill close to Rosemary Bank and move along the western slope of Rockall Bank. In addition, strong winter mixing of up to 1000m depth causes a significant contribution of surface water at depth and vise versa. Sediment coring on carbonate mounds and subsequent U series dating of coral skeletons has revealed up to 5m thick Holocene coral reef structures. Combined U series and 14C dating on those corals allows reconstructing upper intermediate water reservoir ages almost continuously for the entire Holocene. Here we present a compilation of 40 reservoir ages from western Rockall Bank and Porcupine Seabight that span from 400 years PB to ~11000 years BP representing water masses between 610 and 750m depth. Reservoir ages vary remarkably between as low as 150 years to up to 800 years throughout the Holocene. Variable reservoir ages are recorded at the beginning of the Holocene having mean values of about 450-500 years. The Mid-Holocene warm phase between 8500 and 6000 years BP revealed stunningly small and constant reservoir ages of about 200±150 years indicating extremely well ventilated upper intermediate waters. Than reservoir ages rise towards values as high as 700 years and drop down again to about 500 years at 4000 years BP. During the past 4000 years reservoir ages remain far more stable at 450- 500 years. Such changes in upper intermediate water ventilation agree with changes in Northern Hemisphere climate and oceanography recorded by other sedimentary proxies such

  8. [Response of the ant community to attributes of fragments and vegetation in a northeastern Atlantic Rain Forest area, Brazil].

    PubMed

    Gomes, Juliana P; Iannuzzi, Luciana; Leal, Inara R

    2010-01-01

    The objective of this study was to determine the effects of forest fragmentation on ant richness in a landscape of Atlantic Forest in Northeast Brazil. More specifically, the ant richness was related to the attributes of fragments (area and distance from the fragment central point to the edge), landscape (forest cover surrounding the fragments), and tree community (plant density, richness, and percentage of shade tolerant species). The surveys were carried out in 19 fragments located in Alagoas State from October 2007 to March 2008. Samples were collected through a 300 m transect established in the center of each fragment, where 30 1-m² leaf litter samples were collected at 10 m intervals. A total of 146 ant species was collected, which belonged to 42 genera, 24 tribes and nine subfamilies. The attributes of fragments and landscape did not influence ant richness. On the other hand, tree density explained ca. 23% of ant richness. In relation to functional groups, both density and richness of trees explained the richness of general myrmicines (the whole model explained ca. 42% of the variation in this group) and percentage of shade tolerant trees explained the richness of specialist predator ants (30% for the whole model). These results indicate that ant fauna is more influenced by vegetation integrity than by fragment size, distance to edge or forest cover surrounding fragments. PMID:21271055

  9. Family-level AMBI is valid for use in the north-eastern Atlantic but not for assessing the health of microtidal Australian estuaries

    NASA Astrophysics Data System (ADS)

    Tweedley, James R.; Warwick, Richard M.; Clarke, K. Robert; Potter, Ian C.

    2014-03-01

    Analysis of benthic macroinvertebrate samples at a higher taxonomic level than species, e.g. family, potentially provides a more cost-effective protocol for environmental impact assessments and monitoring as it requires less time, funds and taxonomic expertise. Using the AMBI database, species ecological group scores are shown to be coherent within families. Faunal data from a wide range of environmental impact scenarios in the north-eastern Atlantic demonstrate that AMBI, calculated from mean values for families, exhibits a strong linear relationship with species-level AMBI, the correlation improving by using square-root transformed rather than untransformed abundances. In many regions of the world, however, the sensitivity of benthic macroinvertebrates to environmental perturbations is unknown, precluding the use of AMBI for environmental assessments. Yet the families are essentially the same as in the AMBI database. The utility of family-level AMBI is tested using data for four south-western Australian estuaries previously subjected to environmental quality assessments, but where only 17 species of the 144 taxa are included in the AMBI database. Although family-level AMBI scores reflect differences in environmental quality spatially and temporally within an estuary, they do not follow variations in environmental quality among estuaries. Indeed, south-western Australia estuaries are numerically dominated by families with high AMBI scores, probably due to the detrimental effects of natural accumulations of organic material in estuaries with long residence times. As taxonomic distinctness follows trends in environmental quality among estuaries, as well as temporally and spatially within a system, it provides an appropriate substitute for assessing the 'heath' of microtidal estuaries.

  10. Airborne PM2.5 Chemical Components and Low Birth Weight in the Northeastern and Mid-Atlantic Regions of the United States

    PubMed Central

    Bell, Michelle L.

    2012-01-01

    Background: Previous studies on air pollutants and birth outcomes have reported inconsistent results. Chemical components of particulate matter ≤ 2.5 µm (PM2.5) composition are spatially -heterogeneous, which might contribute to discrepancies across PM2.5 studies. Objectives: We explored whether birth weight at term is affected by PM2.5, PM10 (PM ≤ 10 µm), and gaseous pollutants. Methods: We calculated exposures during gestation and each trimester for PM2.5 chemical components, PM10, PM2.5, carbon monoxide, nitrogen dioxide, ozone, and sulfur dioxide for births in 2000–2007 for states in the northeastern and mid-Atlantic United States. Associations between exposures and risk of low birth weight (LBW) were adjusted by family and individual characteristics and region. Interaction terms were used to investigate whether risk differs by race or sex. Results: Several PM2.5 chemical components were associated with LBW. Risk increased 4.9% (95% CI: 3.4, 6.5%), 4.7% (3.2, 6.2%), 5.7% (2.7, 8.8%), and 5.0% (3.1, 7.0%) per interquartile range increase of PM2.5 aluminum, elemental carbon, nickel, and titanium, respectively. Other PM2.5 chemical components and gaseous pollutants showed associations, but were not statistically significant in multipollutant models. The trimester associated with the highest relative risk differed among pollutants. Effect estimates for PM2.5 elemental carbon and nickel were higher for infants of white mothers than for those of African-American mothers, and for males than females. Conclusions: Most exposure levels in our study area were in compliance with U.S. Environmental Protection Agency air pollution standards; however, we identified associations between PM2.5 components and LBW. Findings suggest that some PM2.5 components may be more harmful than others, and that some groups may be particularly susceptible. PMID:23008268

  11. Africa.

    ERIC Educational Resources Information Center

    Happel, Sue; Loeb, Joyce

    Although the activities in this unit are designed primarily for students in the intermediate grades, the document's text, illustrations, and bibliographic references are suitable for anyone interested in learning about Africa. Following a brief introduction and map work, the document is arranged into six sections. Section 1 traces Africa's history…

  12. Africa.

    ERIC Educational Resources Information Center

    Martz, Carlton

    2001-01-01

    This publication explores issues related to Africa. It examines the U.S. response to the Barbary pirate states (Morocco, Algiers, Tunis, Tripoli) in the early 19th century; the current AIDS crisis in Africa; and 14th century Mali and other Islamic lands through the eyes of Ibn Battuta, who traveled throughout the Muslim world. Each article…

  13. Evaluation and improvement of sticky traps as monitoring tools for Glossina austeni and G. brevipalpis (Diptera: Glossinidae) in north-eastern KwaZulu-Natal, South Africa.

    PubMed

    Green, K Kappmeier; Venter, G J

    2007-12-01

    The attractiveness of various colours, colour combinations and sizes of sticky traps of the 3-dimensional trap (3DT), cross-shaped target (XT), rectangular screen (RT) and monopanels were evaluated for their efficacy to capture Glossina austeni Newstead and G. brevipalpis Newstead in north-eastern KwaZulu-Natal, South Africa. The 3-dimensional shapes of the XT and 3DT in light blue (l.blue) and white were significantly (ca. 3.1-6.9 times) better than the RT for G. austeni. On bicoloured XTs, G. austeni landed preferentially on electric blue (e.blue) (58%) and black (63%) surfaces when used with white; while for G. brevipalpis, significantly more landed on e.blue (60-66%) surfaces when used with l.blue, black or white surfaces. Increased trap size increased the catches of G. brevipalpis females and both sexes of G. austeni significantly. Temoocid and polybutene sticky materials were equally effective and remained durable for 2-3 weeks. The glossy shine of trap surfaces did not have any significant effect on the attraction and landing responses of the two species. The overall trap efficiency of the e.blue/l.blue XT was 23% for G. brevipalpis and 28% for G. austeni, and that of the e.blue/black XT was 16% for G. brevipalpis and 51% for G. austeni. Larger monopanels, painted e.blue/black on both sides, increased the catches of G. austeni females significantly by up to four times compared to the standard e.blue/black XT. This monopanel would be recommended for use as a simple and cost effective survey tool for both species in South Africa. PMID:17997867

  14. Freshwater diatom influx in intertropical Atlantic: Relationships with continental records from Africa

    NASA Astrophysics Data System (ADS)

    Gasse, Françoise; Stabell, Bjørg; Fourtanier, Elizabeth; van Iperen, Yolanda

    1989-09-01

    Diatom assemblages from modern West African rivers and from lacustrine sediments subjected to deflation represent the present-day sources of continental diatoms to the sea. Diatom productivity in large rivers is high, especially for the genus Melosira. Windblown diatoms derive mainly from the central and northern Sahara (summer dust plume) where saline chloride-water assemblages are widespread, or from the southern edge of the Sahara (winter dust plume) where Melosira-rich assemblages of dilute water predominate. Freshwater diatom peaks in Atlantic cores may reflect (1) phases of increased river influx, correlated with humid episodes on the continent or (2) phases of enhanced deflation and wind transport during arid episodes (the single hypothesis for fine sediments from mid-ocean sites). Genus Melosira dominates the freshwater assemblages of many modern and fossil marine samples, whatever the transport agent is. Therefore, it is not an accurate paleoclimate indicator by itself, but associated taxa may provide information on the environmental and geographical origin of the displaced diatoms. This tentative approach shows that freshwater diatoms in Atlantic cores may be a good tool for reconstructing paleoclimates and for establishing continent-ocean correlations if species analyses are made and if the continental distribution of the taxa encountered is considered.

  15. Detachment and steep normal faulting in Atlantic oceanic crust west of Africa

    USGS Publications Warehouse

    Reston, T.J.; Ruoff, O.; McBride, J.H.; Ranero, C.R.; White, Robert S.

    1996-01-01

    Improved images of the internal structure of Early Cretaceous North Atlantic crust reveal both probable detachment faults and more steeply dipping normal faults. The detachment faults occur as subhorizontal structures passing ???1.5 km beneath fault blocks without offset; several steeper block-bounding faults appear to detach onto these structures. However, the detachments are bounded to the west (ridgeward) by presumably younger, more steeply west-dipping normal faults. In one possible interpretation, the detachment and the steep faults belong to the same "rolling-hinge" extension system. An intriguing alternative is that a phase of detachment faulting, perhaps related to increased magmatic activity, was succeeded by localized amagmatic extension along steeper and more deeply penetrating faults.

  16. Predicting Atlantic seasonal hurricane activity using outgoing longwave radiation over Africa

    NASA Astrophysics Data System (ADS)

    Karnauskas, Kristopher B.; Li, Laifang

    2016-07-01

    Seasonal hurricane activity is a function of the amount of initial disturbances (e.g., easterly waves) and the background environment in which they develop into tropical storms (i.e., the main development region). Focusing on the former, a set of indices based solely upon the meridional structure of satellite-derived outgoing longwave radiation (OLR) over the African continent are shown to be capable of predicting Atlantic seasonal hurricane activity with very high rates of success. Predictions of named storms based on the July OLR field and trained only on the time period prior to the year being predicted yield a success rate of 87%, compared to the success rate of NOAA's August outlooks of 53% over the same period and with the same average uncertainty range (±2). The resulting OLR indices are statistically robust, highly detectable, physically linked to the predictand, and may account for longer-term observed trends.

  17. A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-Eastern Tropical Upwelling System.

    NASA Astrophysics Data System (ADS)

    Faye, Saliou; Lazar, Alban; Sow, Bamol; Gaye, Amadou

    2015-09-01

    The climatological seasonal cycle of the sea surface temperature (SST) in the north-eastern tropical Atlantic (7-25°N, 26-12°W) is studied using a mixed layer heat budget in a regional ocean general circulation model. The region, which experiences one of the larger SST cycle in the tropics, forms the main part of the Guinea Gyre. It is characterized by a seasonally varying open ocean and coastal upwelling system, driven by the movements of the intertropical convergence zone (ITCZ). The model annual mean heat budget has two regimes schematically. South of roughly 12°N, advection of equatorial waters, mostly warm, and warming by vertical mixing, is balanced by net air-sea flux. In the rest of the domain, a cooling by vertical mixing, reinforced by advection at the coast, is balanced by the air-sea fluxes. Regarding the seasonal cycle, within a narrow continental band, in zonal mean, the SST early decrease (from September, depending on latitude, until December) is driven by upwelling dynamics off Senegal and Mauritania (15°-20°N), and instead by air-sea fluxes north and south of these latitudes. Paradoxically, the later peaks of upwelling intensity (from March to July, with increasing latitude) essentially damp the warming phase, driven by air-sea fluxes. The open ocean cycle to the west, is entirely driven by the seasonal net air-sea fluxes. The oceanic processes significantly oppose it, but for winter north of ~18°N. Vertical mixing in summer-autumn tends to cool (warm) the surface north (south) of the ITCZ, and advective cooling or warming by the geostrophic Guinea Gyre currents and the Ekman drift. This analysis supports previous findings on the importance of air-sea fluxes offshore. It mainly offers quantitative elements on the modulation of the SST seasonal cycle by the ocean circulation, and particularly by the upwelling dynamics. Keywords: SST, upwelling, circulation, heat budget, observations, modeling

  18. First report of geophilid centipedes of the genus Ribautia (Myriapoda: Chilopoda: Geophilomorpha) from the Atlantic Forest biome, with description of a new miniature species from Misiones Province, Northeastern Argentina.

    PubMed

    Pereira, Luis Alberto

    2014-01-01

    Ribautia paranaensis sp. nov. a new miniature species of geophilid centipede from the Upper Paraná Atlantic Forest (the westernmost of the fifteen ecoregions comprising the Atlantic Forest biome sensu Di Bitetti et al. 2003), is herein described and illustrated. The new species is characterized by having the coxal organs grouped in clusters (one of these in each coxopleuron of the ultimate leg-bearing segment) and a claw-like pretarsus in the ultimate legs; these traits being shared by three other Neotropical members of the genus, i.e., R. combinata Pereira, Uliana & Minelli, 2006 (from the Amazonian rainforest of Peru), R. jakulicai Pereira, 2007 (from the Yungas rainforest of Northwestern Argentina), and R. lewisi Pereira, 2013 (collected in a gallery forest in the Mesopotamian region, Northeastern Argentina). R. paranaensis sp. nov. represents the first report of Ribautia Brölemann, 1909 in the entire Atlantic Forest biome, and the third confirmed record of the taxon from Argentina. PMID:24871738

  19. Northeastern Summer Electricity Market Alert

    EIA Publications

    2013-01-01

    The National Weather Service declared an excessive-heat warning for much of the Mid-Atlantic and northeastern United States, including major electric markets covering Philadelphia, Boston, Washington, D.C., and New York City. This report highlights the wholesale electricity market activity occurring in response to the higher-than-normal electricity demand caused by the heat wave.

  20. Understanding the life of a sandy beach polychaete of functional importance - Scolelepis squamata (Polychaeta: Spionidae) on Belgian sandy beaches (northeastern Atlantic, North Sea)

    NASA Astrophysics Data System (ADS)

    Speybroeck, Jeroen; Alsteens, Lotte; Vincx, Magda; Degraer, Steven

    2007-08-01

    The cosmopolitan sandy beach polychaete Scolelepis squamata constitutes an important food resource for juvenile flatfish and wading birds in the northeastern Atlantic, thus playing an important role in sandy beach ecosystem functioning. However, its population dynamics and life history in this part of the world have gone widely uninvestigated. Eight beach transects on Belgian sandy beaches were sampled monthly from October 2003 until October 2004, in order to investigate seasonal trends in the species' abundance, biomass, secondary production, and patterns in reproduction and zonation. Average density, modal density and modal biomass (ash-free dry weight) (mean average density = 169 ± 9 SE ind/m 2; mean modal density = 505 ± 38 SE ind/m 2; mean modal biomass = 0.25 ± 0.02 SE g/m 2) did not exhibit major seasonal changes, whereas average biomass (0.081 ± 0.005 SE g/m 2) and individuals and biomass per strip transect (IST = 16286 ± 1330 SE ind/m; BMST = 7.8 + 0.7 SE g/m) did, peaking in May 2004. Production was calculated at 1.9 g/(m 2*year) (size-frequency method, SFM) and 0.88 g/(m 2*year) (mass specific growth rate method, MSGR) and mean annual biomass was 0.797 g/m 2; resulting in a P/B ratio of 2.40/year (SFM) and 1.11/year (MSGR), which is intermediate to moderately low compared to other polychaete species. Gravid individuals were found from February until August and a single recruitment period was observed from July until September. An average sex ratio of 1.41 ± 0.08 SE was calculated, with a female predominance. Highest densities (>200 ind/m 2) were mostly found above 3 m above MLLWS and at a median grain size from 190 to 320 μm. Average modal or peak density along each transect was situated from 3.95 m up to 4.40 m above MLLWS, in contrast to some other studies where the species was restricted to mid-tidal levels. Significant differences in elevation of peak density were found between non-gravid (411 ± 4 SE cm) and gravid (402 ± 5 SE cm) animals

  1. Biodiversity patterns of the marine benthic fauna on the Atlantic coast of tropical Africa in relation to hydroclimatic conditions and paleogeographic events

    NASA Astrophysics Data System (ADS)

    Lœuff, Pierre Le; von Cosel, Rudo

    1998-06-01

    Five different hydroclimatic regions are recognized in the tropical eastern Atlantic: the northern alternance region (Cape Blanc - Cape Verga), the atypical tropical region (Cape Palmas - border Benin/Nigeria), the southern alternance region (Cape Lopez - Cape Frio), all with periodical upwelling of colder water, and two intercalated typical tropical regions with warm water and reduced salinity. The faunal richness in the regions with upwelling is higher than in the typical tropical regions because many benthic species avoid warm and reduced salinity water. Faunistic exchange and affinity are greater between the upwelling zones and the bordering temperate zones. The cold regions are also more similar in faunal composition. Benthic communities in both tropical and temperate eastern Atlantic are not fundamentally different. Species diversity of benthic invertebrates in tropical West Africa is about the same order of magnitude as in Europe and the Mediterranean. Hydroclimatic conditions (upwelling, salinity reduction and internal waves with drastic temperature changes) and absence of coral reef formations do not favour the establishment and thriving of a warm stenohaline and stenotherm fauna in West Africa. Paleozoogeographic events, such as the formation of a large Euro-West African tropical province during the Miocene after the breakup of the Tethys, repeated climate deteriorations during Pliocene and Pleistocene with reductions of the tropical zone, sea level changes and large-scale extinction of warm-tropical species, are also factors responsible for the current low biodiversity in the tropical eastern Atlantic. Some species survived in two major relict pockets in Senegal and southern Angola with particular ecological conditions.

  2. A new 200 Ma paleomagnetic pole for Africa, and paleo-secular variation scatter from Central Atlantic Magmatic Province (CAMP) intrusives in Morocco (Ighrem and Foum Zguid dykes)

    NASA Astrophysics Data System (ADS)

    Palencia-Ortas, A.; Ruiz-Martínez, V. C.; Villalaín, J. J.; Osete, M. L.; Vegas, R.; Touil, A.; Hafid, A.; McIntosh, G.; van Hinsbergen, D. J. J.; Torsvik, T. H.

    2011-06-01

    Available apparent polar wander (APW) paths for the 200 Ma configuration of Pangea, just prior to the opening of the Central Atlantic Ocean, differ as much as 10o in arc length. Here, we add new data from northwest Africa for this time, obtained from the northeast-trending Foum-Zguid and Ighrem dykes (ca. 200 Ma). These dykes form part of the northern domain of the Central Atlantic Magmatic Province (CAMP), and crosscut the Anti-Atlas Ranges in Morocco, and compositionally correspond to quartz-normative tholeiites intruded in continental lithosphere shortly before the opening of the Central Atlantic Ocean. The Foum-Zguid dyke has been intensively studied, whereas the Ighrem dyke has received less scientific focus. We sampled both dykes for paleomagnetic investigation along 100 km of each dyke (12 sites for Foum-Zguid and 11 for Ighrem, 188 samples included in the final analyses). Rock magnetic experiments indicate a mixture of multidomain and single-domain magnetite and/or low-Ti titanomagnetite particles as the principal remanence carriers. In both dykes, the primary nature of the characteristic remanent magnetization is supported by positive contact tests, related to Fe-metasomatism or baked overprints of the corresponding sedimentary country rocks. The directions of the characteristic magnetization exhibit exclusively normal polarity. Site-mean virtual geomagnetic poles are differently grouped in each dyke, suggesting distinct geomagnetic secular variation records. The Foum-Zguid paleomagnetic pole (N= 12, PLat= 67.9°N, PLon= 247.9°E, κ= 125, A95= 3.9°) plots close to that of Ighrem (N= 11, PLat= 78.4°N, PLon= 238.2°E, κ= 47, A95= 6.7°), confirming those mineralogical and geochemical evidences supporting that they represent dissimilar magmatic stages. Virtual geomagnetic poles dispersion from both dykes (S= 10.5°13.0°8.1°) is in line with those obtained from recent studies of a CAMP-related dyke in Iberia and results from CAMP lavas in the Argana

  3. Knowledge and use of medicinal plants by local specialists in an region of Atlantic Forest in the state of Pernambuco (Northeastern Brazil)

    PubMed Central

    Gazzaneo, Luiz Rodrigo Saldanha; de Lucena, Reinaldo Farias Paiva; de Albuquerque, Ulysses Paulino

    2005-01-01

    The study of local knowledge about natural resources is becoming increasingly important in defining strategies and actions for conservation or recuperation of residual forests. This study therefore sought to: collect information from local populations concerning the use of Atlantic Forest medicinal plants; verify the sources of medicinal plants used; determine the relative importance of the species surveyed, and; calculate the informant consensus factor in relation to medicinal plant use. Data was obtained using semi-structured forms to record the interviewee's personal information and topics related to the medicinal use of specific plants. The material collected represent 125 plants, distributed among 61 botanical families, with little participation of native plants. This study demonstrated that local people tend to agree with each other in terms of the plants used to treat blood-related problems, but cite a much more diverse group of plants to treat problems related to the respiratory and digestive systems – two important categories in studies undertaken in different parts of the world. The local medicinal flora is largely based on plants that are either cultivated or obtained from anthropogenic zones, possibly due to the use and access restrictions of the legally protected neighboring forest. Despite these restrictions, the species with the highest use-value by this community was Pithecellobium cochliocarpum (Gomez) Macb., a native plant of the Atlantic Forest. PMID:16270911

  4. Knowledge and use of medicinal plants by local specialists in an region of Atlantic Forest in the state of Pernambuco (Northeastern Brazil).

    PubMed

    Gazzaneo, Luiz Rodrigo Saldanha; de Lucena, Reinaldo Farias Paiva; de Albuquerque, Ulysses Paulino

    2005-01-01

    The study of local knowledge about natural resources is becoming increasingly important in defining strategies and actions for conservation or recuperation of residual forests. This study therefore sought to: collect information from local populations concerning the use of Atlantic Forest medicinal plants; verify the sources of medicinal plants used; determine the relative importance of the species surveyed, and; calculate the informant consensus factor in relation to medicinal plant use. Data was obtained using semi-structured forms to record the interviewee's personal information and topics related to the medicinal use of specific plants. The material collected represent 125 plants, distributed among 61 botanical families, with little participation of native plants. This study demonstrated that local people tend to agree with each other in terms of the plants used to treat blood-related problems, but cite a much more diverse group of plants to treat problems related to the respiratory and digestive systems - two important categories in studies undertaken in different parts of the world. The local medicinal flora is largely based on plants that are either cultivated or obtained from anthropogenic zones, possibly due to the use and access restrictions of the legally protected neighboring forest. Despite these restrictions, the species with the highest use-value by this community was Pithecellobium cochliocarpum (Gomez) Macb., a native plant of the Atlantic Forest. PMID:16270911

  5. Exposure of small mammals to ticks and rickettsiae in Atlantic Forest patches in the metropolitan area of Recife, North-eastern Brazil.

    PubMed

    Dantas-Torres, Filipe; Aléssio, Filipe Martins; Siqueira, Daniel Barreto; Mauffrey, Jean-François; Marvulo, Maria Fernanda V; Martins, Thiago F; Moraes-Filho, Jonas; Camargo, Maria Cecília G O; D'Auria, Sandra Regina Nicoletti; Labruna, Marcelo B; Silva, Jean Carlos Ramos

    2012-01-01

    Between December 2007 and March 2009, small mammals were captured in 6 Atlantic Forest patches in Brazil. We assessed tick-host associations and whether they differ among forest strata, sites, seasons, and host age classes or between sexes. Moreover, we assessed the exposure of animals to Rickettsia spp. In total, 432 animals were captured and 808 ticks were found on 32·9% of them. Significant differences were found among host species, collection sites, and forest strata; microhabitat preference was a strong risk factor for tick infestation. The highest tick density rates were recorded in forest fragments settled in rural areas; 91·3% of the ticks were collected from animals trapped in these forest fragments. A high prevalence (68·8%) of antibodies to Rickettsia spp. was detected among animals. This study suggests that disturbed Atlantic Forest fragments provide an environment for ticks and small mammals, which are highly exposed to rickettsiae. It also indicates that forest patches settled in rural areas are usually associated with higher small mammal diversity as well as with higher tick density rates. PMID:22217620

  6. At the Crossroads: Hazard Assessment and Reduction of Health Risks from Arsenic in Private Well Waters of Northeastern United States and Atlantic Canada

    PubMed Central

    Zheng, Yan; Ayotte, Joseph D.

    2014-01-01

    This special issue contains 12 papers that report on new understanding of arsenic hydrogeochemistry, performance of household well water treatment systems, and testing and treatment behaviors of well users in several states of the northeastern region of the United States and Nova Scotia, Canada. The responsibility to ensure water safety of private wells falls on well owners. In the U.S., 43 million Americans, mostly from rural areas, use private wells. In order to reduce As exposure in rural populations that rely on private wells for drinking water, risk assessment, which includes estimation of population at risk of exposure to As above the EPA Maximum Contaminant Level, is helpful but insufficient because it does not identify individual households at risk. Persistent optimism bias among well owners against testing and barriers such as cost of treatment mean that a large percentage of the population will not act to reduce their exposure to harmful substances such as As. If households are in areas with known As occurrence, a potentially large percentage of well owners will remain unaware of their exposure. To ensure that everyone, including vulnerable populations such as low income families with children and pregnant women, is not exposed to arsenic in their drinking water, alternative action will be required and warrants further research. PMID:25466685

  7. At the crossroads: Hazard assessment and reduction of health risks from arsenic in private well waters of the northeastern United States and Atlantic Canada.

    PubMed

    Zheng, Yan; Ayotte, Joseph D

    2015-02-01

    This special issue contains 12 papers that report on new understanding of arsenic (As) hydrogeochemistry, performance of household well water treatment systems, and testing and treatment behaviors of well users in several states of the northeastern region of the United States and Nova Scotia, Canada. The responsibility to ensure water safety of private wells falls on well owners. In the U.S., 43 million Americans, mostly from rural areas, use private wells. In order to reduce As exposure in rural populations that rely on private wells for drinking water, risk assessment, which includes estimation of population at risk of exposure to As above the EPA Maximum Contaminant Level, is helpful but insufficient because it does not identify individual households at risk. Persistent optimistic bias among well owners against testing and barriers such as cost of treatment mean that a large percentage of the population will not act to reduce their exposure to harmful substances such as As. If households are in areas with known As occurrence, a potentially large percentage of well owners will remain unaware of their exposure. To ensure that everyone, including vulnerable populations such as low income families with children and pregnant women, is not exposed to arsenic in their drinking water, alternative action will be required and warrants further research. PMID:25466685

  8. At the crossroads: Hazard assessment and reduction of health risks from arsenic in private well waters of the northeastern United States and Atlantic Canada

    USGS Publications Warehouse

    Zheng, Yan; Ayotte, Joseph

    2015-01-01

    This special issue contains 12 papers that report on new understanding of arsenic (As) hydrogeochemistry, performance of household well water treatment systems, and testing and treatment behaviors of well users in several states of the northeastern region of the United States and Nova Scotia, Canada. The responsibility to ensure water safety of private wells falls on well owners. In the U.S., 43 million Americans, mostly from rural areas, use private wells. In order to reduce As exposure in rural populations that rely on private wells for drinking water, risk assessment, which includes estimation of population at risk of exposure to As above the EPA Maximum Contaminant Level, is helpful but insufficient because it does not identify individual households at risk. Persistent optimistic bias among well owners against testing and barriers such as cost of treatment mean that a large percentage of the population will not act to reduce their exposure to harmful substances such as As. If households are in areas with known As occurrence, a potentially large percentage of well owners will remain unaware of their exposure. To ensure that everyone, including vulnerable populations such as low income families with children and pregnant women, is not exposed to arsenic in their drinking water, alternative action will be required and warrants further research.

  9. New species of the genus Elachisina (Gastropoda: Elachisinidae) from northeastern Brazil.

    PubMed

    Cunha, Carlo M; Santos, Franklin N; Lima, Silvio F B

    2016-01-01

    The family Elachisinidae Ponder, 1985 includes minute marine gastropods that live predominantly in the sublittoral zone (Ponder & Keyzer 1998; Rolán & Rubio 2001; Rolán & Gofas 2003). Most elachisinids have been included in the genus Elachisina Dall, 1918 based on their shell morphology (Warén 1996; Rolán & Rubio 2001; Rolán & Gofas 2003), consequently, very little is known about the habitat and ecological niche of the species (Ponder & Keyzer 1998; Rolán & Gofas 2003). Elachisina floridana (Rehder, 1943) is the only Atlantic congener collected alive, and is known to live beneath rocks and in rocky crevices in the intertidal zone to about 1 m depth in the Bahamas and Caribbean Sea (Ponder 1985; Ponder & Keyzer 1998; Rolán & Gofas 2003; Redfern 2013). Eastern Atlantic E. canarica (Nordsieck & García-Talavera, 1979) was also collected alive from the Canary Islands, but with no information on the habitat (Rolán & Gofas 2003). The islands of the northeastern Atlantic and West Africa are the regions with the greatest Elachisina richness known, totaling nine species (Rolán & Rubio 2001; Rolán & Gofas 2003). Only E. floridana has been recognized so far to be widely distributed throughout the Western Atlantic (Rolán & Gofas 2003; Rios 2009; Redfern 2013). PMID:27470791

  10. MID-ATLANTIC LANDCOVER CHANGE DATA BROWSER

    EPA Science Inventory

    The Mid-Atlantic region is comprised of southern New York, southern and western New Jersey, Pennsylvania, West Virginia, Maryland, Virginia, northeastern North Carolina, Delaware, and Washington, DC. It is an ecosystem rich in streams, wetlands, forests, estuaries, breeding birds...

  11. The ancient tropical rainforest tree Symphonia globulifera L. f. (Clusiaceae) was not restricted to postulated Pleistocene refugia in Atlantic Equatorial Africa.

    PubMed

    Budde, K B; González-Martínez, S C; Hardy, O J; Heuertz, M

    2013-07-01

    Understanding the history of forests and their species' demographic responses to past disturbances is important for predicting impacts of future environmental changes. Tropical rainforests of the Guineo-Congolian region in Central Africa are believed to have survived the Pleistocene glacial periods in a few major refugia, essentially centred on mountainous regions close to the Atlantic Ocean. We tested this hypothesis by investigating the phylogeographic structure of a widespread, ancient rainforest tree species, Symphonia globulifera L. f. (Clusiaceae), using plastid DNA sequences (chloroplast DNA [cpDNA], psbA-trnH intergenic spacer) and nuclear microsatellites (simple sequence repeats, SSRs). SSRs identified four gene pools located in Benin, West Cameroon, South Cameroon and Gabon, and São Tomé. This structure was also apparent at cpDNA. Approximate Bayesian Computation detected recent bottlenecks approximately dated to the last glacial maximum in Benin, West Cameroon and São Tomé, and an older bottleneck in South Cameroon and Gabon, suggesting a genetic effect of Pleistocene cycles of forest contraction. CpDNA haplotype distribution indicated wide-ranging long-term persistence of S. globulifera both inside and outside of postulated forest refugia. Pollen flow was four times greater than that of seed in South Cameroon and Gabon, which probably enabled rapid population recovery after bottlenecks. Furthermore, our study suggested ecotypic differentiation-coastal or swamp vs terra firme-in S. globulifera. Comparison with other tree phylogeographic studies in Central Africa highlighted the relevance of species-specific responses to environmental change in forest trees. PMID:23572126

  12. The ancient tropical rainforest tree Symphonia globulifera L. f. (Clusiaceae) was not restricted to postulated Pleistocene refugia in Atlantic Equatorial Africa

    PubMed Central

    Budde, K B; González-Martínez, S C; Hardy, O J; Heuertz, M

    2013-01-01

    Understanding the history of forests and their species' demographic responses to past disturbances is important for predicting impacts of future environmental changes. Tropical rainforests of the Guineo-Congolian region in Central Africa are believed to have survived the Pleistocene glacial periods in a few major refugia, essentially centred on mountainous regions close to the Atlantic Ocean. We tested this hypothesis by investigating the phylogeographic structure of a widespread, ancient rainforest tree species, Symphonia globulifera L. f. (Clusiaceae), using plastid DNA sequences (chloroplast DNA [cpDNA], psbA-trnH intergenic spacer) and nuclear microsatellites (simple sequence repeats, SSRs). SSRs identified four gene pools located in Benin, West Cameroon, South Cameroon and Gabon, and São Tomé. This structure was also apparent at cpDNA. Approximate Bayesian Computation detected recent bottlenecks approximately dated to the last glacial maximum in Benin, West Cameroon and São Tomé, and an older bottleneck in South Cameroon and Gabon, suggesting a genetic effect of Pleistocene cycles of forest contraction. CpDNA haplotype distribution indicated wide-ranging long-term persistence of S. globulifera both inside and outside of postulated forest refugia. Pollen flow was four times greater than that of seed in South Cameroon and Gabon, which probably enabled rapid population recovery after bottlenecks. Furthermore, our study suggested ecotypic differentiation—coastal or swamp vs terra firme—in S. globulifera. Comparison with other tree phylogeographic studies in Central Africa highlighted the relevance of species-specific responses to environmental change in forest trees. PMID:23572126

  13. Consequences of the trans-Atlantic slave trade on medicinal plant selection: plant use for cultural bound syndromes affecting children in Suriname and Western Africa.

    PubMed

    Vossen, Tessa; Towns, Alexandra; Ruysschaert, Sofie; Quiroz, Diana; van Andel, Tinde

    2014-01-01

    Folk perceptions of health and illness include cultural bound syndromes (CBS), ailments generally confined to certain cultural groups or geographic regions and often treated with medicinal plants. Our aim was to compare definitions and plant use for CBS regarding child health in the context of the largest migration in recent human history: the trans-Atlantic slave trade. We compared definitions of four CBS (walk early, evil eye, atita and fontanels) and associated plant use among three Afro-Surinamese populations and their African ancestor groups in Ghana, Bénin and Gabon. We expected plant use to be similar on species level, and assumed the majority to be weedy or domesticated species, as these occur on both continents and were probably recognized by enslaved Africans. Data were obtained by identifying plants mentioned during interviews with local women from the six different populations. To analyse differences and similarities in plant use we used Detrended Component Analysis (DCA) and a Wald Chi-square test. Definitions of the four cultural bound syndromes were roughly the same on both continents. In total, 324 plant species were used. There was little overlap between Suriname and Africa: 15 species were used on two continents, of which seven species were used for the same CBS. Correspondence on family level was much higher. Surinamese populations used significantly more weedy species than Africans, but equal percentages of domesticated plants. Our data indicate that Afro-Surinamers have searched for similar plants to treat their CBS as they remembered from Africa. In some cases, they have found the same species, but they had to reinvent the largest part of their herbal pharmacopeia to treat their CBS using known plant families or trying out new species. Ideas on health and illness appear to be more resilient than the use of plants to treat them. PMID:25372485

  14. Consequences of the Trans-Atlantic Slave Trade on Medicinal Plant Selection: Plant Use for Cultural Bound Syndromes Affecting Children in Suriname and Western Africa

    PubMed Central

    Vossen, Tessa; Towns, Alexandra; Ruysschaert, Sofie; Quiroz, Diana; van Andel, Tinde

    2014-01-01

    Folk perceptions of health and illness include cultural bound syndromes (CBS), ailments generally confined to certain cultural groups or geographic regions and often treated with medicinal plants. Our aim was to compare definitions and plant use for CBS regarding child health in the context of the largest migration in recent human history: the trans-Atlantic slave trade. We compared definitions of four CBS (walk early, evil eye, atita and fontanels) and associated plant use among three Afro-Surinamese populations and their African ancestor groups in Ghana, Bénin and Gabon. We expected plant use to be similar on species level, and assumed the majority to be weedy or domesticated species, as these occur on both continents and were probably recognized by enslaved Africans. Data were obtained by identifying plants mentioned during interviews with local women from the six different populations. To analyse differences and similarities in plant use we used Detrended Component Analysis (DCA) and a Wald Chi-square test. Definitions of the four cultural bound syndromes were roughly the same on both continents. In total, 324 plant species were used. There was little overlap between Suriname and Africa: 15 species were used on two continents, of which seven species were used for the same CBS. Correspondence on family level was much higher. Surinamese populations used significantly more weedy species than Africans, but equal percentages of domesticated plants. Our data indicate that Afro-Surinamers have searched for similar plants to treat their CBS as they remembered from Africa. In some cases, they have found the same species, but they had to reinvent the largest part of their herbal pharmacopeia to treat their CBS using known plant families or trying out new species. Ideas on health and illness appear to be more resilient than the use of plants to treat them. PMID:25372485

  15. Assessment of carbon storage under rainforests in Humic Hapludox along a climosequence extending from the Atlantic coast to the highlands of northeastern Brazil.

    PubMed

    Araujo, Jane Kelly Silva; de Souza Júnior, Valdomiro Severino; Marques, Flávio Adriano; Voroney, Paul; da Silva Souza, Regilene Angelica

    2016-10-15

    An understanding of the stock of soil organic carbon (SOC) in the umbric epipedon of Oxisols located in the tropical forests surrounded by a semi-arid region is limited but essential because of their importance in the global cycle of carbon (C). The purpose of this study was to assess the effects of climatic (temperature and rainfall), soil organic matter (SOM) composition and litter on the stability of C in surfaces and subsurfaces in five Humic Oxisols along a 475-km climosequence from 143 to 963ma.s.l. in a tropical environment in northeastern Brazil. We assessed vertical changes in SOC; soil total nitrogen (N); C from the microbial biomass; δ(13)C, δ(15)N and the humified composition of SOM; the composition of the humin (HUM) fraction by Fourier Transform Infrared (FTIR); and Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) at depth. The elemental and isotopic composition of the litter samples were analyzed in all areas studied. The results indicated that the current climate and recalcitrant organic compounds are not preponderant factors in the formation of the umbric epipedon, as suggested by the partial influence of temperature and rainfall on SOM. In addition, SOM was dominated by easily decomposable compounds, as indicated by the predominance of aliphatic C-H groups in the HUM fraction in the FTIR spectra; by the thermal oxidation through DSC-TG, which revealed that approximately 50% of the HUM was composed easily decomposable compounds; and by the high proportion of organic C present in the microbial biomass. Values of δ(13)C showed a predominance of C3 plant-C in SOM whereas δ(15)N patterns indicated that N dynamics differ among the profiles and drive the accumulation of C. These findings can help to characterize the susceptibility of these soils to changes in climate and land use and the implications for the sequestration of soil C. PMID:27300567

  16. Demography of a deep-sea lantern shark (Etmopterus spinax) caught in trawl fisheries of the northeastern Atlantic: Application of Leslie matrices with incorporated uncertainties

    NASA Astrophysics Data System (ADS)

    Coelho, Rui; Alpizar-Jara, Russell; Erzini, Karim

    2015-05-01

    The deep-sea lantern shark Etmopterus spinax occurs in the northeast Atlantic on or near the bottoms of the outer continental shelves and slopes, and is regularly captured as bycatch in deep-water commercial fisheries. Given the lack of knowledge on the impacts of fisheries on this species, a demographic analysis using age-based Leslie matrices was carried out. Given the uncertainties in the mortality estimates and in the available life history parameters, several different scenarios, some incorporating stochasticity in the life history parameters (using Monte Carlo simulation), were analyzed. If only natural mortality were considered, even after introducing uncertainties in all parameters, the estimated population growth rate (λ) suggested an increasing population. However, if fishing mortality from trawl fisheries is considered, the estimates of λ either indicated increasing or declining populations. In these latter cases, the uncertainties in the species reproductive cycle seemed to be particularly relevant, as a 2-year reproductive cycle indicated a stable population, while a longer (3-year cycle) indicated a declining population. The estimated matrix elasticities were in general higher for the survivorship parameters of the younger age classes and tended to decrease for the older ages. This highlights the susceptibility of this deep-sea squaloid to increasing fishing mortality, emphasizing that even though this is a small-sized species, it shows population dynamics patterns more typical of the larger-sized and in general more vulnerable species.

  17. Formation of African Easterly Waves and Mesoscale Convective Systems over Eastern Africa and its Implication to Tropical Cyclogenesis over Eastern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Lin, Yuh-Lang

    2009-07-01

    The formation of African easterly waves and mesoscale convective systems in eastern North Africa and its impacts on the tropical cyclogenesis over the eastern Atlantic Ocean is studied. Based on numerical simulations, AEWs can be produced by vortex shedding from the EH. The lee vortex is generated mainly by the blocking of the EH and helped by the horizontal shear associated with the northeasterly wind and the jet passing through the Turkana channel. The MCS was originated from the moist convection over the EH triggered by diurnal sensible heating. When the MCS moved to the lee of the mountain, it merged with the lee vortex of the AEW train and formed the coupled AEW-MCS system. Numerical simulations of a regional climate model indicate that the simulated fields do possess the AEW characteristics and the convection was generated over the EH, and the pre-Alberto AEW-MCS system was generated near the lee of the EH. Finer-resolution numerical simulations demonstrate that the vortex generated on the lee and MCS over the mountain eventually merge and become an AEW-MCS system which might serve as a precursor of tropical cyclone.

  18. Diurnal variations and modulation by easterly waves of the size distribution of convective cloud clusters over West Africa and the Atlantic Ocean

    SciTech Connect

    Machado, L.A.T.; Duvel, J.Ph.; Desbois, M. )

    1993-01-01

    Short time-scale fluctuations of the size distribution of tropical convective cloud clusters for July to September 1989 were studied using Meteosat data. A cluster at a given brightness-temperature threshold was defined as the area covered by adjacent cloudy pixels with brightness temperature lower than the threshold. The clusters were classified according to the area covered and the position of their center of mass. Over land regions of West Africa the size distribution underwent a coherent diurnal behavior with development of small cells between noon and 1500 LST. Over the Atlantic Ocean, the highest cloudiness had a weak maximum extent in early morning, while cloudiness at lower levels was more extended in the afternoon. This diurnal behavior was primarily due to large cloud clusters, suggesting that the diurnal variation over the ocean resulted from internal variations of large convective systems and not from the initiation of convection at a given hour of the day. This was confirmed by the analysis of 15 large convective systems propagating over the ocean. The authors have ascertained that the high cloud cover was maximized within the trough of eastrly waves. The cluster size was dependent upon the wave amplitude with a larger mean cluster size when the amplitude was largr. The trough phase of the wave was found to promote the development of large clusters more than it favored the initial stage of convection. 30 refs., 11 figs.

  19. The complex post-rift evolution of the South Atlantic margin, South Africa: new insights from joint inversion of apatite (U-Th)/He and fission track thermochronometry.

    NASA Astrophysics Data System (ADS)

    Wildman, Mark; Brown, Roderick; Persano, Cristina; Beucher, Romain; Stuart, Finlay

    2013-04-01

    The continental edge of southwestern Africa has long been seen as a type example of a high elevation passive margin, with its characteristic topography forming during or shortly after rifting (c. 130 Ma). Recent work along the South Atlantic passive margin has highlighted the importance of interactions between rift-tectonics, mantle flow and dynamic topography on controlling margin evolution, however, the temporal relationship between these processes is still poorly understood. There is now increasing evidence from satellite imagery, onshore field observations (e.g. Viola et al., 2012) and offshore sedimentary basin analysis (e.g. Hirsch et al., 2010) that suggests that these processes have resulted in a much more complex structural and thermal history along the margin than previously thought. A critical step towards developing a better understanding of the post-rift evolution of this margin is to quantify the surface response (i.e. uplift and erosion) to these major structural and thermal events. Apatite fission track analysis (AFTA) has been used world-wide as a powerful means of extracting quantitative constraints on the timing and rate of major episodes of onshore denudation. Previous AFTA studies in SW Africa have identified two distinct cooling events occurred during early and late Cretaceous, respectively. However, in places AFT ages vary significantly over relatively short distances and this has been interpreted to indicate local differential erosion levels controlled by tectonic displacements related to fault reactivation. A limitation of the AFT system is that it is sensitive to a temperature range of c. 120-60°C and therefore is unable to evaluate the magnitude of denudation episodes where the amounts are less than c. 1.5-2 km. So while the Cretaceous history of erosion is well established from existing AFTA data, the details of the timing and amount of erosion occurring during the Cenozoic remain relatively poorly constrained. The apatite (U

  20. Pore-Water Quality in the Clay-Silt Confining Units of the Lower Miocene Kirkwood Formation and Hypothetical Effects on Water Quality in the Atlantic City 800-Foot Sand, Northeastern Cape May County, New Jersey, 2001

    USGS Publications Warehouse

    Szabo, Zoltan; Keller, Elizabeth A.; Defawe, Rose M.

    2006-01-01

    Pore water was extracted from clay-silt core samples collected from a borehole at Ocean View, west of Sea Isle City, in northeastern Cape May County, New Jersey. The borehole intersects the lower Miocene Kirkwood Formation, which includes a thick sand and gravel unit between two clay-silt units. The sand and gravel unit forms a major confined aquifer in the region, known as the Atlantic City 800-foot sand, the major source of potable water along the Atlantic Coast of southern New Jersey. The pore water from the core is of interest because the borehole intersects the aquifer in an area where the ground water is sodium-rich and sulfidic. Locally in the aquifer in central and southern Cape May County, sodium concentrations are near the New Jersey secondary drinking-water standard of 50 mg/L (milligrams per liter), and typically are greater than 30 mg/L, but chloride and sulfate do not approach their respective secondary drinking-water standards except in southernmost Cape May County. Pore waters from the confining units are suspected to be a source of sodium, sulfur, and chloride to the aquifer. Constituent concentrations in filtered pore-water samples were determined using the inductively coupled plasma-mass spectrometry analytical technique to facilitate the determination of low-level concentrations of many trace constituents. Calcium-sodium-sulfate-bicarbonate, calcium-chloride-sulfate, calcium-sulfate, and sodium-sulfate-chloride-bicarbonate type waters characterize samples from the deepest part of the confining unit directly overlying the aquifer (termed the 'lower' confining unit). A sodium-chloride-sulfate type water is dominant in the composite confining unit below the aquifer. Sodium, chloride, and sulfate became increasingly dominant with depth. Pore water from the deepest sample recovered (1,390 ft (feet) below land surface) was brackish, with concentrations of sodium, chloride, and sulfate of 5,930, 8,400, and 5,070 mg/L, respectively. Pore-water samples

  1. How kilometric sandy shoreline undulations correlate with wave and morphology characteristics: preliminary analysis on the Atlantic coast of Africa

    NASA Astrophysics Data System (ADS)

    Idier, D.; Falqués, A.

    2014-04-01

    Sandy coasts are characterized by a number of rhythmic patterns like, amongst others, shoreline undulations or sandwaves at a kilometric scale. One hypothesis for their formation is that high angle waves (large incidence angle with respect to shore normal) could induce an instability of the shoreline (Ashton et al., 2001). More recently, a scaling for their wavelength has also been proposed (van den Berg et al., 2014). The existing studies rely mainly on modelling but quantitative field tests are lacking. We aim at investigating how both the formation hypothesis of these shoreline undulations and the theoretical scaling do fit with nature at a global scale. The first step, which is the goal of this paper, is to set up the methodology by analyzing the Atlantic African coast as test site. First, based on global databases, shoreline wavelength LS, wave characteristics (obliquity θW and wavelength λW) and mean shoreface slope β are determined. Then the wave obliquity is confronted with the presence of shoreline undulations. Finally the values of the ratio β LS / λW are estimated and discussed in comparison with the estimate of van den Berg et al. (2014). It is found that the correlation between shoreline sandwave occurrence and wave obliquity is very good, allowing the identification of 5 new potential unstable shoreline stretches, whereas the results on the scaling are not conclusive and deserve further investigations.

  2. Multiple, discrete inversion episodes revealed by apatite fission track analysis along the southernmost Atlantic margin of South Africa

    NASA Astrophysics Data System (ADS)

    Wildman, M.; Brown, R. W.; Persano, C.; Stuart, F. M.

    2013-12-01

    The morpho-tectonic history of the western South African continental margin and interior plateau remains enigmatic. Recent investigations of offshore sediment accumulation and interpretations of onshore structural and geomorphological observations have highlighted the complex geological evolution of South Africa throughout the Mesozoic and Cenozoic. Moreover, advances in geodynamic modelling approaches have explored the crustal response to varying styles of rifting and the influence of mantle upwelling beneath the African plate. These geological observations and models, however, require validation from quantitative constraints on the surface response (i.e. uplift and erosion) to syn- and post rift thermal and tectonic processes Over the last two decades, low temperature thermochronometry, particularly apatite fission track analysis (AFTA) and apatite (U-Th)/He, have been effective tools in providing these constraints by tracking the time-temperature history of rocks through c. 60 - 110°C and 80 - 40°C, respectively. The unique ability of AFTA to constrain both the timing and nature of sample cooling rests largely on the sensitivity of fission track annealing to temperature. Here, we present new AFT data from a suite of samples across the entire western continental margin of South Africa which contributes to a now extensive AFT dataset spanning the entire sub-continent. This dataset broadly invokes at least two discrete episodes of cooling driven by km scale denudation at c. 130 Ma, following rifting and break up of West Gondwana, and 90 Ma as a response to renewed tectonic uplift. However, the apparent lack of correlation of AFT age with elevation or with distance from the coast highlight the spatial and temporal variability of post-rift cooling that may be related to Mid-Cretaceous structural reactivation along the margin. We also present thermal history modelling using the Bayesian transdimensional inverse modelling approach of QTQt (Gallagher, 2012). Modelling

  3. NEAMTWS-ECTE1: The First Enlarged Communication Test Exercise of the Tsunami Early Warning and Mitigation System in the North-eastern Atlantic, the Mediterranean and connected seas

    NASA Astrophysics Data System (ADS)

    Necmioglu, O.; Rudloff, A.; Matias, L. M.; Schindele, F.; Comoglu, M.; Meral Ozel, N.

    2012-04-01

    During the seventh session of the Intergovernmental Coordination Group for the Tsunami Early Warning and Mitigation System in the North-eastern Atlantic, the Mediterranean and connected seas (ICG/NEAMTWS) held in Paris, France, from 23 to 25 November 2010, a task team on Communication Test and Tsunami Exercises (TT-CT&TE) was established. The task team was responsible for the preparation and conduct of the First Enlarged Communication Test Exercise (NEAMTWS-ECTE1) and the organization of its assessment. The aim of the test exercise was to refine procedures for testing the communication of tsunami alert messages between National Tsunami Warning Centres and all Tsunami Warning Focal Points (TWFPs), including speed and availability within NEAM region. Earlier small size tests, conducted during the previous intersessional period, highlighted the importance of having other communication method like Global Telecommunication System (GTS), and therefore the utilization of GTS during the NEAMTWS-ECTE1 was another aim of the exercise. NEAMTWS-ECTE1 was conducted on 10 August 2011 with the participation of 139 end-users belonging to 42 agencies in 31 countries. A methodical and detailed analysis of the ECTE1 has been provided to ICG/NEAMTWS as a report, where 27 new recommendations were provided in order to improve all aspects of a Communication Test Exercise (CTE), ranging from the manual to the interaction with the media, but especially focusing on the technical and procedural improvements. Some technical problems during the NEAMTWS-ECTE1 have helped to clearly identify certain operational and procedural issues on which NEAMTWS should conclude some guidelines. A Small Scale Communication Test (SSCT-1) focusing on the problem areas of NEAMTWS-ECTE1 was conducted on 26 October 2011 as a follow-up exercise to consolidate the lessons learnt from NEAMTWS-ECTE1. Both NEAMTWS-ECTE-1 and SSCT-1 clearly indicates that message dissemination using fax is the least effective

  4. Very short-lived bromomethanes measured by the CARIBIC observatory over the North Atlantic, Africa and South-East Asia during 2009-2013

    NASA Astrophysics Data System (ADS)

    Wisher, A.; Oram, D. E.; Laube, J. C.; Mills, G. P.; van Velthoven, P.; Zahn, A.; Brenninkmeijer, C. A. M.

    2013-11-01

    Short-lived organic brominated compounds make up a significant part (~20%) of the organic bromine budget in the atmosphere. Emissions of these compounds are highly variable and there are limited measurements, particularly in the extra-tropical upper troposphere/lower stratosphere and tropical troposphere. Measurements of five short-lived bromomethanes (VSLB) were made in air samples collected on the CARIBIC project aircraft over three flight routes; Germany to Venezuela/Columbia during 2009-2011, Germany to South Africa during 2010 and 2011 and Germany to Thailand/Kuala Lumpur, Malaysia during 2012 and 2013. In the tropical troposphere, as the most important entrance region to the stratosphere, we observe a total mean organic bromine derived from these compounds across all flights at 10-12 km altitude of 3.4 ± 1.5 ppt. Individual mean tropical tropospheric mixing ratios across all flights were 0.43, 0.74, 0.14, 0.23 and 0.11 ppt for CHBr3, CH2Br2, CHBr2Cl, CHBrCl2 and CH2BrCl respectively. The highest levels of VSLS-derived bromine (4.20 ± 0.56 ppt) were observed in flights between Bangkok and Kuala Lumpur indicating that the South China Sea is an important source region for these compounds. Across all routes, CHBr3 and CH2Br2 accounted for 34% (4.7-71) and 48% (14-73) respectively of total bromine derived from the analysed VSLB in the tropical mid-upper troposphere totalling 82% (54-89). In samples collected between Germany and Venezuela/Columbia, we find decreasing mean mixing ratios with increasing potential temperature in the extra-tropics. Tropical mean mixing ratios are higher than extra-tropical values between 340-350 K indicating that rapid uplift is important in determining mixing ratios in the lower tropical tropopause layer in the West Atlantic tropics. O3 was used as a tracer for stratospherically influenced air and we detect rapidly decreasing mixing ratios for all VSLB above ~100 ppb O3 corresponding to the extra-tropical tropopause layer.

  5. Very short-lived bromomethanes measured by the CARIBIC observatory over the North Atlantic, Africa and Southeast Asia during 2009-2013

    NASA Astrophysics Data System (ADS)

    Wisher, A.; Oram, D. E.; Laube, J. C.; Mills, G. P.; van Velthoven, P.; Zahn, A.; Brenninkmeijer, C. A. M.

    2014-04-01

    Short-lived organic brominated compounds make up a significant part of the organic bromine budget in the atmosphere. Emissions of these compounds are highly variable and there are limited measurements, particularly in the extra-tropical upper troposphere/lower stratosphere and tropical troposphere. Measurements of five very short-lived bromomethanes (VSLB) were made in air samples collected on the CARIBIC project aircraft over three flight routes; Germany to Venezuela/Columbia during 2009-2011, Germany to South Africa during 2010 and 2011 and Germany to Thailand/Kuala Lumpur, Malaysia during 2012 and 2013. In the tropical troposphere, as the most important entrance region to the stratosphere, we observe a total mean organic bromine derived from these compounds across all flights at 10-12 km altitude of 3.4 ± 1.5 ppt. Individual mean tropical tropospheric mixing ratios across all flights were 0.43, 0.74, 0.14, 0.23 and 0.11 ppt for CHBr3, CH2Br2, CHBr2Cl, CHBrCl2 and CH2BrCl respectively. The highest levels of VSLB-derived bromine (4.20 ± 0.56 ppt) were observed in flights between Bangkok and Kuala Lumpur indicating that the South China Sea is an important source region for these compounds. Across all routes, CHBr3 and CH2Br2 accounted for 34% (4.7-71) and 48% (14-73) respectively of total bromine derived from the analysed VSLB in the tropical mid-upper troposphere totalling 82% (54-89). In samples collected between Germany and Venezuela/Columbia, we find decreasing mean mixing ratios with increasing potential temperature in the extra-tropics. Tropical mean mixing ratios are higher than extra-tropical values between 340-350 K indicating that rapid uplift is important in determining mixing ratios in the lower tropical tropopause layer in the West Atlantic tropics. O3 was used as a tracer for stratospherically influenced air and we detect rapidly decreasing mixing ratios for all VSLB above ∼100 ppb O3 corresponding to the extra-tropical tropopause layer.

  6. West Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    With its vast expanses of sand, framed by mountain ranges and exposed rock, northwestern Africa makes a pretty picture when viewed from above. This image was acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra spacecraft. The Canary Islands can be seen on the left side of the image just off Africa's Atlantic shore. The light brown expanse running through the northern two thirds of the image is the Sahara Desert. The desert runs up against the dark brown Haut Atlas mountain range of Morocco in the northwest, the Atlantic Ocean to the west and the semi-arid (light brown pixels) Sahelian region in the South. The Sahara, however, isn't staying put. Since the 1960s, the desert has been expanding into the Sahelian region at a rate of up to 6 kilometers per year. In the 1980s this desert expansion, combined with over cultivation of the Sahel, caused a major famine across west Africa. Over the summer months, strong winds pick up sands from the Sahara and blow them across the Atlantic as far west as North America, causing air pollution in Miami and damaging coral reefs in the Bahamas and the Florida Keys. The white outlines on the map represent country borders. Starting at the top-most portion of the map and working clockwise, the countries shown are Morocco, Western Sahara, Mauritania, Senegal, Mali, Burkina Fasso, Nigeria, Mali (again), and Algeria. Image by Reto Stockli, Robert Simmon, and Brian Montgomery, NASA Earth Observatory, based on data from MODIS

  7. South Atlantic interbasin exchange

    NASA Technical Reports Server (NTRS)

    Rintoul, Stephen Rich

    1991-01-01

    The exchange of mass and heat between the South Atlantic and the neighboring ocean basins was estimated using hydrographic data and inverse methods, in order to gain information on the links between the deep-water formation processes occurring within the Atlantic and the global thermohaline circulation. Results demonstrate that the global thermohaline cell associated with the formation and export of North Atlantic deep water (NADW) is closed primarily by a 'cold water path' in which deep water leaving the Atlantic ultimately returns as intermediate water entering the basin through Drake Passage. This conclusion conflicts with the suggestion by Gordon (1986) that the global thermohaline circulation associated with the formation of NADW is closed primarily by a 'warm water path', in which the export of NADW is compensated by an inflow of warm Indian Ocean thermocline water south of Africa.

  8. Two new species of the family Niphatidae van Soest, 1980 from Northeastern Brazil (Haplosclerida: Demospongiae: Porifera).

    PubMed

    Santos, George Garcia; Docio, Loyana; Pinheiro, Ulisses

    2014-01-01

    This paper deals with niphatid sponges from the coast of the Bahia State, northeastern coast of the Brazilian shelf (southwestern Atlantic). Two new species are described, Amphimedon estelae sp. nov. and Niphates luizae sp. nov. A taxonomic study of those samples is given, including description and illustrations. Both species were compared with their congeners present in the Atlantic Ocean. PMID:24871419

  9. MISR Images Northeastern Botswana

    NASA Technical Reports Server (NTRS)

    2000-01-01

    MISR images of the Ntwetwe and Sua Pans in northeastern Botswana, acquired on August 18, 2000 (Terra orbit 3553). The left image is a color view from the vertical-viewing (nadir) camera. On the right is a composite of red band imagery in which the 45-degree aft camera data are displayed in blue, 45-degree forward as green, and vertical as red. This combination causes wet areas to appear blue because of the glint-like reflection from water and damp surfaces. Clouds are visible in the upper left corner and right center of each image. The clouds look peculiar in the multi-angle view because geometric parallax resulting from their elevation above the surface causes a misregistration of the individual images making up the composite. This stereoscopic effect provides a way of distinguishing clouds from bright surfaces.

    The images are approximately 250 kilometers across. Ntwetwe and Sua pans are closed interior basins that catch rainwater and surface runoff during the wet season. Seasonal lakes form that may reach several meters in depth. During the dry season the collected waters rapidly evaporate leaving behind dissolved salts that coat the surface and turn it bright ('sua' means salt). The mining town of Sowa is located where the Sua Spit (a finger of grassland extending into the pan) attaches to the shore. Sowa represents headquarters for a JPL contingent carrying out MISR field experiments using the evaporite surface and the grasslands as targets and for Botswana scientists studying migration of groundwaters beneath the pans and surrounding areas. These efforts support the Southern Africa Regional Science Initiative (SAFARI-2000), which is now underway.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

    For more information: http://www-misr.jpl.nasa.gov

  10. South Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    contained within South Africa's boundaries. In the upper righthand corner of the image is the Bay of Maputo, where sits Maputo, the capital of Mozambique. Fires are visible in the northeast corner of the image, near Maputo. Just north of Maputo is where the Limpopo River empties into the Indian Ocean. Tracing the Limpopo inland back toward the west, this river defines the northern boundary of South Africa with both Zimbabwe and Botswana. Johannesburg, the commercial capital of South Africa, can be seen as the greyish pixels in the northeastern region of the country. The country's legislative capital, Pretoria, is about 50 miles north of Johannesburg and 250 miles west of Maputo, in the heart of the Northern Province (formerly known as Transvaal). (Image courtesy Jacques Descloitres, MODIS Land Group, NASA Goddard Space Flight Center)

  11. The morphotectonic history of the Atlantic continental margin of South Africa: insights from combined (U-Th)/He and fission track thermochronometry

    NASA Astrophysics Data System (ADS)

    Wildman, M.; Beucher, R.; Brown, R.; Persano, C.; Stuart, F.; Roelofse, F.

    2012-04-01

    The morphotectonic evolution of the South African continental margins and the interior plateau remains unresolved, with the crux of the debate being whether the present day topography represents an eroded remnant of a Cretaceous elevated interior or if the topography is much younger, developed as a result of Miocene epeirogenic-style uplift. In recent years, advances in the understanding of mantle dynamics have led to an appreciation of its importance as a major controlling factor on the evolution of the South African plateau since the break-up of Gondwana. However, constraints on the timing and amount of uplift derived from geodynamical models are still controversial due to a lack of tight constraints on mantle viscosity and density structure and because of differences in the way the plate motions at the surface are incorporated into the different models. It is therefore essential to obtain more directly relevant empirical observations that can be used to test these models. Low temperature thermochronology (LTT) is a powerful tool well able to address this question by providing constraints on the time-temperature history of rocks, denudation, landscape evolution and tectonic history. Over the past two decades, the main focus of LTT analysis in South Africa has been on Apatite Fission Track Analysis (AFTA) which generally supports a dominant Cretaceous (c. 90Ma) uplift event with km-scale erosion, but spatially as well as temporally variable, in the interior of the plateau. However, AFTA data is unable to provide robust constraints on the Tertiary cooling history due to the temperature range covered by the fission track system (e.g. 60-110°C). The (U-Th)/He method with a lower temperature range (c. 40-75°C) will therefore be more sensitive to more recent and smaller amounts of erosion offers a new opportunity to evaluate the magnitude of Cenozoic denudation in southern Africa. Here we present the first (U-Th)/He ages from SW South Africa, obtained from a transect

  12. Radiative Flux Changes by Aerosols from North America, Europe, and Africa over the Atlantic Ocean: Measurements and Calculations from TARFOX and ACE-2

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Hignett, P.; Livingston, J. M.; Schmid, B.; Chien, A.; Bergstrom, R.; Durkee, P. A.; Hobbs, P. V.; Bates, T. S.; Quinn, P. K.; Condon, Estelle (Technical Monitor)

    1998-01-01

    Aerosol effects on atmospheric radiative fluxes provide a forcing function that is a major source of uncertainty in understanding the past climate and predicting climate change. To help reduce this uncertainty, the 1996 Tropospheric Aerosol Radiative Forcing Experiment (TARFOX) and the 1997 second Aerosol Characterization Experiment (ACE-2) measured the properties and radiative effects of American, European, and African aerosols over the Atlantic. In TARFOX, radiative fluxes and microphysics of the American aerosol were measured from the UK C-130 while optical depth spectra, aerosol composition, and other properties were measured by the University of Washington C-131A and the CIRPAS Pelican. Closure studies show that the measured flux changes agree with those derived from the aerosol measurements using several modelling approaches. The best-fit midvisible single-scatter albedos (approx. 0.89 to 0.93) obtained from the TARFOX flux comparisons are in accord with values derived by independent techniques. In ACE-2 we measured optical depth and extinction spectra for both European urban-marine aerosols and free-tropospheric African dust aerosols, using sunphotometers on the R/V Vodyanitskiy and the Pelican. Preliminary values for the radiative flux sensitivities (Delta Flux / Delta Optical depth) computed for ACE-2 aerosols (boundary layer and African dust) over ocean are similar to those found in TARFOX. Combining a satellite-derived optical depth climatology with the aerosol optical model validated for flux sensitivities in TARFOX provides first-cut estimates of aerosol-induced flux changes over the Atlantic Ocean.

  13. Northeastern Exterior, Northwestern Exterior, & Southwestern Exterior Elevations, Northeastern Interior, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Northeastern Exterior, Northwestern Exterior, & Southwestern Exterior Elevations, Northeastern Interior, Southeastern Interior, & Southwestern Interior Elevations, Floor Plan, and Eastern Corner Detail - Manatoc Reservation, Vale Edge Adirondack, 1075 Truxell Road, Peninsula, Summit County, OH

  14. Effects of Multi-Decadal Variation of SST and Dust Radiative Forcing on Rainfall and Dust Transport over West Africa and Northern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Kim, K. M.; Lau, W. K. M.; Colarco, P. R.

    2014-12-01

    The effects of multi-decadal variations of sea surface temperature (SST) and dust radiative forcing on the West African monsoon rainfall and circulation, and consequent change in dust emission and transport are examined based on model experiments with the NASA GEOS-5 GCM with prescribed SST. SST patterns representing the 1950s and 1980s are obtained based on Singular Value Decomposition (SVD) between Sahel rainfall and global SST distribution, and prescribed for 7-year simulations for each period. Results show that the subtropical high is strengthened and expanded southwestward associated with colder northern Atlantic Ocean SST in 1980s. As a result, the rain band in the tropical Atlantic Ocean and Sahel moves southward and rainfall is reduced over the Sahel. Stronger surface winds associated with strong surface temperature gradients increase dust emission in the southern Saharan desert and northern Sahel. Combined with circulation changes induced by strengthening the subtropical high and reduced wet deposition, dust transport is increased in the deep tropics (10-20N), but reduced in the northern path (20-30N)To examine the effect of aerosol radiative forcing, additional experiments are conducted after dust radiative feedback is turned off. Without aerosol radiative feedback, model still simulate aforementioned contrast between 1980s and 1950s, but the anomalies of Sahel drought and dust transports are a lot weaker. Preliminary results indicate that atmospheric heating due to shortwave absorption by dust provides additional buoyance and lifts dust particles to higher altitudes. Dust radiative forcing also increases meridional temperature gradients and strengthens the African Easterly Jet, resulting in an increased residence time of dust and farther westward transport.

  15. Namib Desert, Namibia, Africa

    NASA Technical Reports Server (NTRS)

    1990-01-01

    One of the driest regions on Earth, the Namib Desert, Namibia, Africa (23.0N, 15.0E) lies adjacent to the Atlantic coast but upwelling oceanic water causes a very stable rainless atmosphere. The few local inland rivers do not reach the sea but instead appear as long indentations where rivers penetrate the dune fields and end as small dry lakes. The vast dune fields are the result of sands deposited over millions of years by the stream flow.

  16. Namib Desert, Namibia, Africa

    NASA Technical Reports Server (NTRS)

    1990-01-01

    One of the driest regions on Earth, the Namib Desert, Namibia, Africa (23.0N, 15.0E) lies adjacent to the Atlantic coast but the upwelling oceanic water causes a very stable rainless atmosphere. The few local inland rivers do not reach the sea but instead, appear as long indentations where they penetrate the dune fields and end as small dry lakes. The vast dune fields are the result of sands deposited over millions of years by the stream flow.

  17. Late-glacial pollen, macrofossils and fish remains in northeastern U.S.A. — The Younger Dryas oscillation. A contribution to the 'North Atlantic seaboard programme' of IGCP-253, 'Termination of the Pleistocene'

    NASA Astrophysics Data System (ADS)

    Peteet, D. M.; Daniels, R. A.; Heusser, L. E.; Vogel, J. S.; Southon, J. R.; Nelson, D. E.

    The late-glacial environmental histories of Allamuchy Pond, New Jersey and Linsley Pond, Connecticut are reconstructed from pollen, macrofossil and fish scale remains. Accelerator mass spectrometry (AMS) 14C dating of seeds and needles indicates that the first organic deposition, evidenced by fossil Picea (spruce) needles, occurred approximately 12,400 BP. A major regional warming began in the northeastern United States at this time, correlative with the Bølling/Allerød warming of Europe and Greenland. The increase in Quercus (oak) pollen and presence of Pinus strobus (white pine) needles demonstrates the magnitude of warming reached at about 11,000 BP. The subsequent decline of thermophilous species and increase in boreal Picea, Abies (fir), Larix (larch), Betula papyrifera (paper birch) and Alnus (alder) from 10,800-10,000 BP was a regional vegetational reversal. Thus we find a North American expression of the Younger Dryas with a mean annual temperature depression of 3-4° C. The subsequent classical southern New England pine pollen zone 'B' and Pinus strobus macrofossils signalled a return to warmer conditions at approximately 10,000 BP, regionally, within approximately 50-100 years. A large increase in Quercus follows. This study is unique in documenting a continuous late-glacial record of fish remains from Allamuchy Pond, New Jersey sediments, indicating that members of the families Centrarchidae (sunfish), Salmonidae (trout), Percidae (perch) and Cyprinidae (minnow) were regionally present.

  18. A phylogenetic hypothesis for Crocodylus (Crocodylia) based on mitochondrial DNA: evidence for a trans-Atlantic voyage from Africa to the New World.

    PubMed

    Meredith, Robert W; Hekkala, Evon R; Amato, George; Gatesy, John

    2011-07-01

    The phylogenetic relationships among extant species of Crocodylus (Crocodylia) have been inconsistently resolved by previous systematic studies. Here we used nearly complete mitochondrial (mt) genomes (∼16,200 base pairs) for all described Crocodylus species, eight of which are new to this study, to derive a generally well-supported phylogenetic hypothesis for the genus. Model-based analyses support monophyly of all Asian+Australian species and paraphyly of Crocodylus niloticus (Nile crocodile) with a monophyletic New World clade nested within this species. Wild-caught Nile crocodiles from eastern populations group robustly with the four New World species to the exclusion of Nile crocodiles from western populations, a result that is also favored by parsimony analyses and by various subpartitions of the overall mt dataset. The fossil record of Crocodylus extends back only to the Late Miocene, while the earliest fossils assigned to C. niloticus and to New World Crocodylus are Pliocene. Therefore, in combination with paleontological evidence, mt DNA trees imply a relatively recent migration of Crocodylus from Africa to the Americas, a voyage that would have covered hundreds of miles at sea. PMID:21459152

  19. Dust storm off Western Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The impacts of Saharan dust storms reach far beyond Africa. Wind-swept deserts spill airborne dust particles out over the Atlantic Ocean where they can enter trade winds bound for Central and North America and the Caribbean. This Moderate Resolution Imaging Spectroradiometer (MODIS) image shows a dust storm casting an opaque cloud of cloud across the Canary Islands and the Atlantic Ocean west of Africa on June 30, 2002. In general it takes between 5 and 7 days for such an event to cross the Atlantic. The dust has been shown to introduce foreign bacteria and fungi that have damaged reef ecosystems and have even been hypothesized as a cause of increasing occurrences of respiratory complaints in places like Florida, where the amount of Saharan dust reaching the state has been increasing over the past 25 years.

  20. The chronology and tectonic style of landscape evolution along the elevated Atlantic continental margin of South Africa resolved by joint apatite fission track and (U-Th-Sm)/He thermochronology

    NASA Astrophysics Data System (ADS)

    Wildman, Mark; Brown, Roderick; Beucher, Romain; Persano, Cristina; Stuart, Fin; Gallagher, Kerry; Schwanethal, James; Carter, Andrew

    2016-03-01

    Atlantic-type continental margins have long been considered "passive" tectonic settings throughout the entire postrift phase. Recent studies question the long-term stability of these margins and have shown that postrift uplift and reactivation of preexisting structures may be a common feature of a continental margin's evolution. The Namaqualand sector of the western continental margin of South Africa is characterized by a ubiquitously faulted basement but lacks preservation of younger geological strata to constrain postrift tectonic fault activity. Here we present the first systematic study using joint apatite fission track and apatite (U-Th-Sm)/He thermochronology to achieve a better understanding on the chronology and tectonic style of landscape evolution across this region. Apatite fission track ages range from 58.3 ± 2.6 to 132.2 ± 3.6 Ma, with mean track lengths between 10.9 ± 0.19 and 14.35 ± 0.22 µm, and mean (U-Th-Sm)/He sample ages range from 55.8 ± 31.3 to 120.6 ± 31.4 Ma. Joint inverse modeling of these data reveals two distinct episodes of cooling at approximately 150-130 Ma and 110-90 Ma with limited cooling during the Cenozoic. Estimates of denudation based on these thermal histories predict approximately 1-3 km of denudation coinciding with two major tectonic events. The first event, during the Early Cretaceous, was driven by continental rifting and the development and removal of synrift topography. The second event, during the Late Cretaceous, includes localized reactivation of basement structures as well as regional mantle-driven uplift. Relative tectonic stability prevailed during the Cenozoic, and regional denudation over this time is constrained to be less than 1 km.

  1. Fisheries. Population of origin of Atlantic cod.

    PubMed

    Nielsen, E E; Hansen, M M; Schmidt, C; Meldrup, D; Grønkjaer, P

    2001-09-20

    Most of the world's cod (Gadus morhua) fisheries are now tightly regulated or closed altogether. Being able to link individual fish to their population of origin would assist enormously in policing regulations and in identifying poachers. Here we show that microsatellite genetic markers can be used to assign individual cod from three different populations in the northeastern Atlantic Ocean to their population of origin. PMID:11565021

  2. Sex-structure, depth distribution, intermoult period and reproductive pattern of the deep-sea red crab Chaceon affinis (Brachyura, Geryonidae) in two populations in the north-eastern Atlantic

    NASA Astrophysics Data System (ADS)

    Biscoito, Manuel; Freitas, Mafalda; Pajuelo, José G.; Triay-Portella, Raül; Santana, José I.; Costa, Ana L.; Delgado, João; González, José A.

    2015-01-01

    This work investigated the biology of Chaceon affinis in two isolated populations of the Atlantic Ocean, including depth distribution, sexual structure, reproductive patterns and intermoult period. Males were larger and heavier than females. Mean size decreased with depth for both males and females. The highest abundance was found at 600-799 m of depth for males and at 800-999 m depth stratum for females. The highest abundance of ovigerous females was found at the 800-999 m depth stratum. Of the different ovaries' colour or colour shades recorded, only six categories were histologically characterized. The presence of spermatophores in the spermatheca of females in carapace stages II and III suggests that spermatophores are viable and used during the intermoult period. The size at sexual maturity in females was estimated at 104.4-104.7 mm carapace width (CW) in Madeira, and 109.3-110.5 mm CW in the Canary Islands. Only three categories of testes were identified. Mature testes consisted in a large mass, with highly coiled vasa deferentia visible to the naked eye. The size at sexual maturity in males was estimated at 113.8 mm CW in Madeira and 118.9 mm CW in the Canaries. The relative growth of males showed significant changes along the ontogeny and size at which allometric growth changes, as an indicator of morphometric maturity, occurred between 103.2 and 103.6 mm CW in Madeira and between 111.4 and 113.1 mm CW in the Canaries. In females, size at which allometric growth changes was found for maximum width of fifth abdominal somite (AS5W) at 98.2 mm CW in Madeira and 103.0 mm CW in the Canaries. The size at maturity obtained for C. affinis indicates that the minimum landing size (MLS) should not be set smaller than 125 mm CW in Madeira and 130 mm CW in the Canaries. This conservative MLS, higher than length at functional maturity, would safeguard immature individuals until they reach the size at which they can contribute to the reproductive capacity of the

  3. Temporal chemical variations within lowermost jurassic tholeiitic magmas of the Central Atlantic Magmatic Province

    NASA Astrophysics Data System (ADS)

    Salters, Vincent J. M.; Ragland, P. C.; Hames, W. E.; Milla, K.; Ruppel, C.

    The Central Atlantic Magmatic Province (CAMP), of greater extent than any other large igneous province (LIP) yet identified surrounds the Central Atlantic in eastern North America, northeastern South America, western Africa, and southwestern Europe. It covers over 7×109 km2 and was active for no more than 4 Ma. Virtually all CAMP rocks are mafic tholeiites, and include both intrusives and extrusives. The most extensive intrusives, diabase (dolerite) dikes, occur in three main swarms on Pangaea: NW-, NE-, and NS trending. These mafic tholeiites can be classified based on their Ti contents into low-Ti (LTi), intermediate-Ti (ITi), and high-Ti (HTi). The NE swarm contains primarily the ITi magma type, whereas the NW swarm is heterogeneous and contains all three types. The N-S swarm contains highly evolved (high-Fe) quartz tholeiites in North America and ITi rocks in South America. These dike swarms can be correlated across the Atlantic basin on the basis of composition and attitude. The two principal magma types within the CAMP, LTi and ITi, were derived from mantle sources that were compositionally similar and contained both continental lithospheric and asthenospheric components. Compared with other large igneous provinces the CAMP basalts show depleted geochemical characteristics. Compositional differences between them are primarily due to differences in depth and degree of melting; LTi represents the deepest and greatest degrees of melting. The temporal progression of the chemical characteristics indicate deeper melting with time, which is consistent with a shallow (such as crustal thinning) and passive origin for the break-up of the Pangaean continent.

  4. Anisotropic tomography of the Atlantic ocean

    NASA Astrophysics Data System (ADS)

    Silveira, G.; Stutzmann, E.

    2003-04-01

    We present a regional tri-dimensional model of the Atlantic Ocean with anisotropy. The model, derived from Rayleigh and Love phase velocity measurements, is defined from the Moho down to 300 km depth with a lateral resolution of about 500 km and is presented in terms of average isotropic S-wave velocity, azimuthal anisotropy and transverse isotropy. The cratons beneath North America, Brazil and Africa are clearly associated with fast S-wave velocity anomalies. The Mid Atlantic Ridge is a shallow structure in the North Atlantic corresponding to a negative velocity anomaly down to about 150 km depth. In contrast, the ridge negative signature is visible in the South Atlantic down to the deepest depth inverted, that is 300~km depth. This difference is probably related to the presence of hot-spots along or close to the ridge axis in the South Atlantic and may indicate a different mechanism for the ridge between the North and South Atlantic. Negative velocity anomalies are clearly associated with hot-spots from the surface down to at least 300km depth, they are much broader that the supposed size of the hot-spots and seem to be connected along a North-South direction. Down to 100 km depth, a fast S-wave velocity anomaly is extenting from Africa into the Atlantic Ocean within the zone defined as the Africa superswell area. This result indicates that the hot material rising from below does not reach the surface in this area but may be pushing the lithosphere upward. In most parts of the Atlantic, the azimuthal anisotropy directions remain stable with increasing depth. Close to the ridge, the fast S-wave velocity direction is roughly parallel to the sea floor spreading direction. The hot-spot anisotropy signature is striking beneath Bermuda, Cape Verde and Fernando Noronha islands where the fast S-wave velocity direction seems to diverge radially from the hot-spots. The Atlantic average radial anisotropy is similar to that of the PREM model, that is positive down to about

  5. From Europe to America: pliocene to recent trans-atlantic expansion of cold-water north atlantic molluscs.

    PubMed

    Vermeij, Geerat J

    2005-12-01

    Data on the geographical distribution, phylogeny and fossil record of cool-temperate North Atlantic shell-bearing molluscs that live in waters shallower than 100 m depth belong to two biogeographic provinces, one in eastern North America north of Cape Cod, the other in northern Europe. Amphi-Atlantic species, which are found in both provinces, comprise 30.8% of the 402 species in the northeastern Atlantic and 47.3% of the 262 species in the northwestern Atlantic. Some 54.8% of these amphi-Atlantic species have phylogenetic origins in the North Pacific. Comparisons among fossil Atlantic faunas show that amphi-Atlantic distributions became established in the Middle Pliocene (about 3.5 million years ago), and that all represent westward expansions of European taxa to North America. No American taxa spread eastward to Europe without human assistance. These results are in accord with previous phylogeographic studies among populations within several amphi-Atlantic species. Explanations for the unidirectional expansion of species across the Atlantic remain uncertain, but may include smaller size and greater prior extinction of the North American as compared to the European fauna and biased transport mechanisms. Destruction of the European source fauna may jeopardize faunas on both sides of the Atlantic. PMID:16271981

  6. Evolutionary diversity among Atlantic coast mangroves

    NASA Astrophysics Data System (ADS)

    Dodd, Richard S.; Rafii, Zara A.; Fromard, François; Blasco, François

    1998-06-01

    Current knowledge of intraspecific variation of mangrove species is limited in terms of rangewide distributions and is mostly restricted to morphological analyses, which have indicated a high degree of homogeneity. However, our analyses of the aliphatic hydrocarbon and triterpenoid fraction of foliar waxes (by gas chromatography and mass spectroscopy) of mangrove species ( Rhizophora mangle, Avicennia germinans and Laguncularia racemosa) from Gabon in West Africa and French Guiana in South America show significant genetic differentiation between eastern and western Atlantic provenances. The greater diversity in lipid composition, and the tendency for longer carbon chain lengths in all taxa from Africa, may suggest that American mangroves exhibit derived characteristics. A consequence of this hypothesis would be that Atlantic mangroves are unlikely to have dispersed from the Tethys via the Pacific, as has been proposed by some authors. More widespread sampling within the Atlantic and east Pacific region is needed to support and confirm these results.

  7. West Africa

    Atmospheric Science Data Center

    2013-04-16

    ... article title:  Hazy and Dusty Skies over Western Africa     View Larger Image ... of agricultural fires that were burning throughout western Africa during December and early January, and was likely to have been ...

  8. Southern Africa

    Atmospheric Science Data Center

    2013-04-16

    article title:  Southern Africa     View larger JPEG image ... These Multi-angle Imaging SpectroRadiometer (MISR) images of Africa were acquired on August 25, 2000, during Terra orbit 3655. The left ... of smoke plumes and haze. The southern tip of South Africa is at the bottom of the image, and Zambia is at the top. Distinctive ...

  9. WRF/ARPEGE-CLIMAT simulated climate trends over West Africa

    NASA Astrophysics Data System (ADS)

    Vigaud, N.; Roucou, P.; Fontaine, B.; Sijikumar, S.; Tyteca, S.

    2011-03-01

    The Weather Regional Forecast (WRF) model is used in this study to downscale low-resolution data over West Africa. First, the performance of the regional model is estimated through contemporary period experiments (1981-1990) forced by ARPEGE-CLIMAT GCM output (ARPEGE) and ERA-40 re-analyses. Key features of the West African monsoon circulation are reasonably well represented. WRF atmospheric dynamics and summer rainfall compare better to observations than ARPEGE forcing data. WRF simulated moisture transport over West Africa is also consistent in both structure and variability with re-analyses, emphasizing the substantial role played by the West African Monsoon (WAM) and African Easterly Jet (AEJ) flows. The statistical significance of potential climate changes for the A2 scenario between 2032 and 2041 is enhanced in the downscaling from ARPEGE by the regional experiments, with substantial rainfall increases over the Guinea Gulf and eastern Sahel. Future scenario WRF simulations are characterized by higher temperatures over the eastern Tropical Atlantic suggesting more evaporation available locally. This leads to increased moisture advection towards eastern regions of the Guinea Gulf where rainfall is enhanced through a strengthened WAM flow, supporting surface moisture convergence over West Africa. Warmer conditions over both the Mediterranean region and northeastern Sahel could also participate in enhancing moisture transport within the AEJ. The strengthening of the thermal gradient between the Sahara and Guinean regions, particularly pronounced north of 10°N, would support an intensification of the AEJ northwards, given the dependance of the jet to the position/intensity of the meridional gradient. In turn, mid-tropospheric moisture divergence tends to be favored within the AEJ region supporting southwards deflection of moist air and contributing to deep moist convection over the Sahel where late summer rainfall regimes are sustained in the context of the A2

  10. Tropical forcing of the recent rapid Arctic warming in northeastern Canada and Greenland.

    PubMed

    Ding, Qinghua; Wallace, John M; Battisti, David S; Steig, Eric J; Gallant, Ailie J E; Kim, Hyung-Jin; Geng, Lei

    2014-05-01

    Rapid Arctic warming and sea-ice reduction in the Arctic Ocean are widely attributed to anthropogenic climate change. The Arctic warming exceeds the global average warming because of feedbacks that include sea-ice reduction and other dynamical and radiative feedbacks. We find that the most prominent annual mean surface and tropospheric warming in the Arctic since 1979 has occurred in northeastern Canada and Greenland. In this region, much of the year-to-year temperature variability is associated with the leading mode of large-scale circulation variability in the North Atlantic, namely, the North Atlantic Oscillation. Here we show that the recent warming in this region is strongly associated with a negative trend in the North Atlantic Oscillation, which is a response to anomalous Rossby wave-train activity originating in the tropical Pacific. Atmospheric model experiments forced by prescribed tropical sea surface temperatures simulate the observed circulation changes and associated tropospheric and surface warming over northeastern Canada and Greenland. Experiments from the Coupled Model Intercomparison Project Phase 5 (ref. 16) models with prescribed anthropogenic forcing show no similar circulation changes related to the North Atlantic Oscillation or associated tropospheric warming. This suggests that a substantial portion of recent warming in the northeastern Canada and Greenland sector of the Arctic arises from unforced natural variability. PMID:24805345

  11. On the circulation of the northeastern North Atlantic

    NASA Astrophysics Data System (ADS)

    Bersch, Manfred

    1995-09-01

    Along a section from Cape Farvel at the southern tip of Greenland to the Porcupine Bank off the Irish coast (WOCE section A1E/AR7E), obtained in September 1991, geostrophic velocities were calculated from CTD measurements and referenced to velocities recorded by an Acoustic Doppler Current Profiler (ADCP) in the upper 500 m. The mean accuracy of the absolute geostrophic velocities is estimated at±3.6 cm/s, which is comparable to that resulting from the assumption of a layer of no motion. The derived flow field is essentially columnar without a pronounced layer of no motion. Maximum velocities of 20-30 cm/s occur in the upper 1000 m of the East Greenland Current and the Porcupine slope current and at 2000 m depth in the Denmark Strait overflow. The meandering of the Irminger Current crossing the Reykjanes Ridge and an enhanced mesoscale variability along the Rockall Plateau and in the Rockall Trough are indicated. Compared to Schmitz and McCartney (1993) the estimated volume transports suggest an intensified meridional circulation with an increased supply from the subtropics to the Subpolar Mode Water (SPMW) and an increased entrainment of SPMW into the deeper layers. In the bottom layer with densities σ 0 ⩾ 27.80 kg/m 3 a reduced circulation of Iceland-Scotland Overflow Water (ISOW) in the Irminger Basin and a recirculation of ISOW in the Iceland and West European basins are found. About 12 Sv of bottom water are transported southwards and join the Deep Western Boundary Current.

  12. Three new species of Eurypon Gray, 1867 from Northeastern Brazil (Poecilosclerida; Demospongiae; Porifera).

    PubMed

    Santos, George Garcia; França, Fernando; Pinheiro, Ulisses

    2014-01-01

    Three new species of Eurypon from Northeastern Brazil are described: Eurypon clavilectuarium sp. nov.; Eurypon suassunai sp. nov. and Eurypon distyli sp. nov. Samples were collected from the continental shelf of Rio Grande do Norte, Bahia and Paraíba States. While the majority of Atlantic Eurypon species have been described from deep water, two of three new species described in this study were collected from shallow depths. The three new species from Brazil were compared with all other eighteen Eurypon species described from the Atlantic.  PMID:25543569

  13. Geology of northeastern Montana

    USGS Publications Warehouse

    Collier, Arthur J.

    1919-01-01

    A large region in northeastern Montana has never been thoroughly explored by geologists, owing to the fact that it is a part of the Great Plains and the belief that it is too monotonous and uninteresting to tempt anyone to turn aside from the pronounced geologic features a little farther west, for which Montana is noted. This region includes parts of Sheridan, Valley, Phillips, and Blaine counties. Its investigation was begun by Smith in 1908, when he made a geologic survey of the Fort Peck Indian Reservation. Beekly explored a strip of land along the Montana-North Dakota line from Missouri River to the international boundary, and Bauer examined the townships in which Plentywood and Scobey are situated. Their results are here included with those of the writer, who during the field seasons of 1915 and 1916 was engaged in an investigation of the lignite resources of the remainder of this region, which extends from a line within 12 miles of the Montana-North Dakota boundary westward about 200 miles.

  14. East-looking view across Atlantic waters during MA-9 22 orbit

    NASA Technical Reports Server (NTRS)

    1963-01-01

    East looking view across Atlantic waters toward Africa, showing Mauritania and Spanish Sahara photographed from the Mercury-Atlas 9 capsule by Astronaut L. Gordon Cooper Jr., during his 22 orbit Mercury-Atlas 9 (MA-9) spaceflight.

  15. Linkages of remote sea surface temperatures and Atlantic tropical cyclone activity mediated by the African monsoon

    NASA Astrophysics Data System (ADS)

    Taraphdar, Sourav; Leung, L. Ruby; Hagos, Samson

    2015-01-01

    sea surface temperatures (SSTs) in North Atlantic and Mediterranean (NAMED) can influence tropical cyclone (TC) activity in the tropical East Atlantic by modulating summer convection over western Africa. Analysis of 30 years of observations demonstrates that warm NAMED SST is linked to a strengthening of the Saharan heat low and enhancement of moisture and moist static energy in the lower troposphere over West Africa, which favors a northward displacement of the monsoonal front. These processes also lead to a northward shift of the African easterly jet that introduces an anomalous positive vorticity from western Africa to the main development region (50°W-20°E; 10°N-20°N) of Atlantic TCs. By modulating multiple African monsoon processes, NAMED SST explains comparable and approximately one third of the interannual variability of Atlantic TC frequency as that explained by local wind shear and local SST, respectively, which are known key factors that influence Atlantic TC development.

  16. Linkages of Remote Sea Surface Temperatures and Atlantic Tropical Cyclone Activity Mediated by the African Monsoon

    SciTech Connect

    Taraphdar, Sourav; Leung, Lai-Yung R.; Hagos, Samson M.

    2015-01-28

    Warm sea surface temperatures (SSTs) in North Atlantic and Mediterranean (NAMED) can influence tropical cyclone (TC) activity in the tropical East Atlantic by modulating summer convection over western Africa. Analysis of 30 years of observations show that the NAMED SST is linked to a strengthening of the Saharan heat low and enhancement of moisture and moist static energy in the lower atmosphere over West Africa, which favors a northward displacement of the monsoonal front. These processes also lead to a northward shift of the African easterly jet that introduces an anomalous positive vorticity from western Africa to the main development region (50W–20E; 10N–20N) of Atlantic TC. By modulating multiple processes associated with the African monsoon, this study demonstrates that warm NAMED SST explains 8% of interannual variability of Atlantic TC frequency. Thus NAME SST may provide useful predictability for Atlantic TC activity on seasonal-to-interannual time scale.

  17. South Africa

    Atmospheric Science Data Center

    2013-04-16

    ... atmospheric and oceanic conditions. At Elands Bay in South Africa's Western Cape province, about 1000 tons of rock lobsters beached ... red tide. At the same time, people came from across South Africa to gather the undersized creatures for food. The effects of the losses ...

  18. Climate Forcing of North Atlantic Tropical Cyclone Activity over the last 6000 years

    NASA Astrophysics Data System (ADS)

    Donnelly, J. P.; Woodruff, J. D.; Scileppi, E.; Lane, P.

    2006-12-01

    Reconstructions of extreme overwash events in backbarrier lagoons and wetlands from the Caribbean to the northeastern United States show similar patterns of event occurrence. Comparisons with instrumental and historical records indicate that most of these overwash layers were likely deposited by landfalling tropical cyclones. Over the last 6000 years intense tropical cyclones have deposited coarse grained laminae in a coastal lagoon on Vieques, Puerto Rico. Intervals with more frequent intense tropical cyclone strikes occurred at 5600-4200 years ago, 2500-1000 years ago, and 250 years ago to present. Similarly records from backbarrier wetlands in the New York/New Jersey Bight provide evidence of more frequent overwash in the last 300 years and 2200 to 900 years ago. An earlier active interval in New York is also evident and dates to sometime before 2700 years ago. Other shorter records from the northeastern United States also provide evidence of more frequent storm-induced deposition over the last few hundred years following a relative lull in overwash and presumably tropical cyclone landfalls. This increase in tropical cyclone landfalls occurs during the later half of the Little Ice Age (LIA) when sea surface temperatures (SSTs) in the tropics were 2-3°C cooler than modern. Over the last several millennia a coherent pattern of climate change appears to have modulated intense tropical cyclone activity in the North Atlantic. The evolution of El Niño/Southern Oscillation (ENSO) variability over the late Holocene likely played an important role in controlling the frequency of intense tropical cyclones in the entire North Atlantic Basin, with intervals of fewer strong El Niño events being more favorable to intense tropical cyclone activity. In addition, variations in the West African monsoon, possibly tied to ENSO, may be an important control on the frequency of North Atlantic intense tropical cyclones. With increases in intense convective storms over tropical

  19. Africa: "Yonondio."

    ERIC Educational Resources Information Center

    Bendetson, Jane

    1996-01-01

    Recounts a teacher's experiences on a trip to Africa. Describes her pleasant moments with her fellow travelers; her appreciation of the natural setting; her visit to an impoverished native school; and her confrontation with a Maasai warrior. (TB)

  20. 50 CFR 648.25 - Atlantic Mackerel, squid, and butterfish framework adjustments to management measures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Atlantic Mackerel, squid, and butterfish framework adjustments to management measures. 648.25 Section 648.25 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE FISHERIES OF THE NORTHEASTERN UNITED...

  1. 50 CFR 648.21 - Mid-Atlantic Fishery Management Council risk policy.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Mid-Atlantic Fishery Management Council risk policy. 648.21 Section 648.21 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE FISHERIES OF THE NORTHEASTERN UNITED...

  2. Cretaceous paleogeography of Africa

    SciTech Connect

    Hulver, M.L.; Ziegler, A.M.; Rowley, D.B.; Sahagian, D.

    1986-05-01

    Five stage-length maps (Valanginian, Aptian, Cenomanian, Coniacian, and Maestrichtian) of Africa integrate topography/bathymetry, lithofacies, tectonics, and climatically sensitive sediments. These reconstructions differ from currently available maps in their level of detail and accuracy, and in that computer routines were developed to plot all aspects of the maps, including lithofacies patterns. Bathymetric contours were determined from community paleoecology and from thermal subsidence models of the newly opening Atlantic and Indian oceans. Topographic contours have been estimated from uplift models of rift shoulders, as well as from the erosion and sedimentation record of both the internal and marginal basins. The uplift of rift shoulders from Nigeria to Sudan is suggested by the extensive Nubian and equivalent sandstones across north Africa. This Benue-Ngaoundere-Abu Gabra rift system approximately paralleled the paleoequator, and its shoulders must have experienced the high rainfall normally associated with the intertropical convergence zone (ITCZ). In fact, these mountains would have served as a high level heat source, and would have pinned the ITCZ to their summits. Such a system tends to reduce seasonal excursions of the ITCZ, and may have influenced the high biological productivity represented by the oil source rocks of the Arabian peninsula. These sources also lie on the equator and could have resulted from a shelf incursion of the equatorial divergence zone, which is controlled by the ITCZ.

  3. Early Mesozoic cooling from low temperature thermochronology in N Spain and N Africa

    NASA Astrophysics Data System (ADS)

    Grobe, R.; Alvarez-Marrón, J.; Glasmacher, U. A.; Menéndez-Duarte, R.

    2009-04-01

    , Volume 94, Issue 2, pp.193-203. Ghorbal, B.; Bertotti, G.; Foeken, J.; Andriessen, P. (2008). Unexpected Jurassic to Neogene vertical movements in ‘stable' parts of NW Africa revealed by low temperature geochronology. Terra Nova, Volume 20, Number 5, October 2008 , pp. 355-363(9). Jourdan, F.; Marzoli, A.; Bertrand, H.; Cosca, M.; Fontignie, D. (2003). The Northernmost CAMP: 40Ar/39Ar Age, petrology and Sr-Nd-Pb isotope geochemistry of the Kerforne Dike, Brittany, France. In: Hames, W.E., McHone, J.G., Renne, P.R., Ruppel, C. (Eds.), The Central Atlantic Magmatic Province: Insights From Fragments of Pangea. AGU, Geophys. Mon., vol. 136, pp. 209-226. Juez-Larré, J. (2003). Post Late Paleozoic tectonothermal evolution of the northeastern margin of Iberia, assessed by fission-track and (U-T)/He analysis: a case history from the Catalan Coastal Ranges. Ph.D. thesis, Free University of Amsterdam. 200 pp. Marzoli, A.; Renne, P.R.; Piccirillo, E.M.; Ernesto, M.; Bellieni, G.; De Min, A. (1999). Extensive 200-million-year-old continental food basalts of the Central Atlantic magmatic province. Science 284, 616-618. Pe-Piper, G.; Jansa, L.F.; Lambert, R.St.-J. (1992). Early Mesozoic magmatism of the Eastern Canadian margin. In: Puffer, J.H., Ragland, P.C. (Eds.), Eastern North American Mesozoic magmatism. Geol. Soc. Am., Spec. Paper, vol. 268, pp. 13-36. Wilson, M. (1997). Thermal evolution of the Central Atlantic passive margins: continental break-up above a Mesozoic super-plume. J. Geol. Soc. (Lond.) 154, 491-495.

  4. 77 FR 8776 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2012 Atlantic Bluefish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-15

    ... National Oceanic and Atmospheric Administration 50 CFR Part 648 RIN 0648-XA904 Fisheries of the... Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION... commercial harvest levels for bluefish (a low, medium, and high level of harvest). For analysis of impacts...

  5. 78 FR 26523 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2013 and 2014 Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-07

    ... published in the Federal Register on February 20, 2013 (78 FR 11809), and comments were accepted through... National Oceanic and Atmospheric Administration 50 CFR Part 648 RIN 0648-XC432 Fisheries of the...: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA),...

  6. 78 FR 11809 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2013-2014 Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-20

    ... National Oceanic and Atmospheric Administration 50 CFR Part 648 RIN 0648-XC432 Fisheries of the...: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce... high level of harvest). For analysis of impacts of Alternatives 1 and 2 for both 2013 and 2014,...

  7. 76 FR 2640 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2011 Atlantic Bluefish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-14

    ... (RSA) quota, which is deducted from the bluefish TAL (after any applicable transfer) in an amount... recommended bluefish RSA quota. Proposed Commercial Quota and Recreational Harvest Limit Based strictly on the... quota of 9.411 million lb (4,269 mt) and an RHL of 17.882 million lb (8,111 mt). RSA Two...

  8. 75 FR 27221 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2010 Atlantic Bluefish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-14

    ... proposed specifications (75 FR 10450, March 8, 2010), and will not be repeated here. Final Specifications... estimate projected recreational landings for the 2010 fishing year by using a simple linear regression of... RSA Program was published on January 2, 2009 (74 FR 72). Two research projects that would...

  9. 77 FR 25100 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2012 Atlantic Bluefish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-27

    ... published in the Federal Register on February 15, 2012 (77 FR 8776), and comments were accepted through... 19901. The specifications document is also accessible via the Internet at: http://www.nero.noaa.gov... Northeast Regional Office's Web site at www.nero.noaa.gov . Authority: 16 U.S.C. 1801 et seq. Dated:...

  10. 76 FR 65971 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Adjustment to the Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-25

    ... the sub-ACL is set aside for research (75 FR 48874, August 12, 2010). Due to the variability of Canadian catch in the New Brunswick weir fishery, a portion of the buffer between ABC and OY (the buffer to... the amount specified in the buffer. The NMFS Regional Administrator is required to monitor the...

  11. Infectious Disease and the Demography of the Atlantic Peoples.

    ERIC Educational Resources Information Center

    Crosby, Alfred W.

    1991-01-01

    Discusses effects of disease on the Atlantic basin after Christopher Columbus established contact between the hemispheres. Emphasizes the decimation of the native populations of the Americas when exposed to illnesses common in Eurasia and Africa. Relates the epidemics to the development of the slave trade and the rise of the middle class in…

  12. « Younger-Dryas / African Humid Period »: a notable climatic transition over West Africa

    NASA Astrophysics Data System (ADS)

    Skonieczny, C.; Bory, A. J.; Bout-Roumazeilles, V.; Malaizé, B.; Grousset, F. E.; Abouchami, W.; Galer, S. J.; Francois, R. H.

    2013-05-01

    Every year, several hundreds teragrams of dust are emitted from the Sahara and Sahel regions. These mineral particles sensitively track variations in atmospheric circulation and continental aridity. Sediments of the Northeastern Atlantic Tropical Ocean (NEATO) are fed by this intense dust supply and comprise unique long-term archives of past dust emissions. Past modifications of dust characteristics in these sedimentary archives can provide precious information on changes in environmental conditions in source areas (aridity, weathering), as well as on changes in the characteristics of their atmospheric transport (pathways and strength). Over Africa, gradual increases in local insolation due to changes in the Earth's orbit are accompanied by a migration of the precipitation monsoon-system (associated with the InterTropical Convergence Zone, ITCZ) toward the North. This displacement leads to decrease in West African mineral dust emission. Consequently, Saharan and Sahelian dust deposited in the NEATO sedimentary archives represent an exceptional opportunity to document the environmental and climatic changes that have taken place in West Africa throughout the Quaternary and beyond (Rea, 1994). Here we document changes in the terrigenous supplies to the NETAO throughout the last deglaciation using the marine sediment core MD03-2705 located off Mauritania (18°05N; 21°09W; 3085m water depth) and retrieved from a bathymetric dome, 300 meters above the surrounding seafloor. Considering this particular environmental setting, the terrigenous fraction in this record is assumed to be predominantly of aeolian origin. Multi-proxy analyses of the carbonate-free fraction of the sediment were carried-out, including dust fluxes, grain-size, clay mineralogy and geochemical measurements (major and trace elements as well as Sr & Nd isotopes). We will discuss the most significant changes recorded over the studied period: levels dated from the Younger Dryas and the subsequent African

  13. Mesoscale convective complexes in Africa

    SciTech Connect

    Laing, A.G.; Fritsch, J.M. )

    1993-08-01

    Digitized full-disk infrared satellite imagery from the European geostationary satellite (Meteosat) for 1986 and 1987 was used to construct a climatology of mesoscale convective complexes (MCCs) in Africa. One hundred ninety-five systems formed over Africa and its near vicinity during the two-year study period. From this database, characteristics of Africa MCCs were calculated. The results indicate that these MCCs display many of the same characteristics as those found in the Americas, the Indian subcontinent, and the western Pacific region. The systems are predominantly nocturnal and tend to form over or in the immediate vicinity of land. The average lifetime of African MCCs is about 11.5 h. The size distributions of the African systems are also extremely similar to those of the Americas, the Indian subcontinent, and the western Pacific region with most systems exhibiting areas between 2 [times] 10[sup 5] and 3 [times] 10[sup 5] km[sup 2]. The monthly frequency distribution of African systems indicates that peak activity tends to occur during the period of most intense insolation. Like the MCCs in the western Pacific region and the Americas, the African MCCs tend to propagate toward the low-level high-[theta][sub e] air that feeds the convective systems. Systems over northern Africa moved toward the west-southwest, with a few developing into tropical cyclones over the Atlantic. Systems over southeastern Africa generally moved toward the northeast and east. It is concluded that the satellite-observed systems over Africa are essentially the same phenomena as the MCC populations observed over the Americas, the Indian monsoon region, and the western Pacific region. In addition, the large number of MCCs found worldwide (approximately 300-400 per year) indicate that they may be significant contributors to the global tropospheric energy budget and hydrological cycle. 46 refs., 9 figs., 1 tab.

  14. Combined 40Ar/39Ar and Fission-Track study of the Freetown Layered Igneous Complex, Freetown, Sierra Leone, West Africa: Implications for the Initial Break-up of Pangea to form the Central Atlantic Ocean and Insight into the Post-rift Evolution of the Sie

    NASA Astrophysics Data System (ADS)

    Barrie, Ibrahim; Wijbrans, Jan; Andriessen, Paul; Beunk, Frank; Strasser-King, Victor; Fode, Daniel

    2010-05-01

    Sierra Leone lies within the south-western part of the West African Craton and comprises two major Archaean structural divisions: a low-grade granite-greenstone terrane characterised by N-S striking structures and a NW-SE striking highly metamorphosed belt of strained rocks that form the coastal margin of the craton. Intruded into the belt is the Freetown Layered Igneous Complex (FLIC), a tholeiitic magamtic body emplaced prior to or during the break-up of Pangea to form the Central Atlantic Ocean and, forming today the high ground of the coastal outline of Sierra Leone which is one of the most distinctive features on the West African coast. The break-up of Pangaea to form the Central Atlantic and its passive margins began in the Early Jurassic. Geo-tectonically, the break-up was particularly characterised by the formation of the Central Atlantic Magmatic Province (CAMP), covering once-contiguous parts of North America, Europe, Africa and South America. The FLIC forming part of the heart of CAMP is the largest single layered igneous intrusive yet known on either side of the Central Atlantic, measuring on surface, 65 x 14 x 7 km. Geophysical investigations indicate that the intrusion extends offshore to a depth of about 20 km. Geologically the Complex is a rhythmically layered elongated ultramafic-mafic lopolith divisible into 4 major zones each comprising repeated sequences of troctolitic, gabbroic and anorthositic rocks. An idealised unit of layering is from base upwards: dunite, troctolite, olivine-gabbro, leuco-gabbro, gabbro-norite and anorthosite cumulates. 40Ar-39Ar age spectra and 40Ar/36Ar versus 39Ar/36Ar isochron plots obtained by stepwise-heating experiments on plagioclases, biotites and amphiboles from troctolites, olivine-gabbros, gabbro-norites and anorthosites of the four zones yield plateau and isochron ages that seem to depict the cooling history of the Complex after emplacement. The biotites and some of the plagioclases and amphiboles give very

  15. Combined 40Ar/39Ar and Fission-Track study of the Freetown Layered Igneous Complex, Freetown, Sierra Leone, West Africa: Implications for the Initial Break-up of Pangea to form the Central Atlantic Ocean and Insight into the Post-rift Evolution of the Sie

    NASA Astrophysics Data System (ADS)

    Barrie, Ibrahim; Wijbrans, Jan; Andriessen, Paul; Beunk, Frank; Strasser-King, Victor; Fode, Daniel

    2010-05-01

    Sierra Leone lies within the south-western part of the West African Craton and comprises two major Archaean structural divisions: a low-grade granite-greenstone terrane characterised by N-S striking structures and a NW-SE striking highly metamorphosed belt of strained rocks that form the coastal margin of the craton. Intruded into the belt is the Freetown Layered Igneous Complex (FLIC), a tholeiitic magamtic body emplaced prior to or during the break-up of Pangea to form the Central Atlantic Ocean and, forming today the high ground of the coastal outline of Sierra Leone which is one of the most distinctive features on the West African coast. The break-up of Pangaea to form the Central Atlantic and its passive margins began in the Early Jurassic. Geo-tectonically, the break-up was particularly characterised by the formation of the Central Atlantic Magmatic Province (CAMP), covering once-contiguous parts of North America, Europe, Africa and South America. The FLIC forming part of the heart of CAMP is the largest single layered igneous intrusive yet known on either side of the Central Atlantic, measuring on surface, 65 x 14 x 7 km. Geophysical investigations indicate that the intrusion extends offshore to a depth of about 20 km. Geologically the Complex is a rhythmically layered elongated ultramafic-mafic lopolith divisible into 4 major zones each comprising repeated sequences of troctolitic, gabbroic and anorthositic rocks. An idealised unit of layering is from base upwards: dunite, troctolite, olivine-gabbro, leuco-gabbro, gabbro-norite and anorthosite cumulates. 40Ar-39Ar age spectra and 40Ar/36Ar versus 39Ar/36Ar isochron plots obtained by stepwise-heating experiments on plagioclases, biotites and amphiboles from troctolites, olivine-gabbros, gabbro-norites and anorthosites of the four zones yield plateau and isochron ages that seem to depict the cooling history of the Complex after emplacement. The biotites and some of the plagioclases and amphiboles give very

  16. Potential tropical Atlantic impacts on Pacific decadal climate trends

    NASA Astrophysics Data System (ADS)

    Chikamoto, Y.; Mochizuki, T.; Timmermann, A.; Kimoto, M.; Watanabe, M.

    2016-07-01

    The tropical Pacific cooling from the early 1990s to 2013 has contributed to the slowdown of globally averaged sea surface temperatures (SSTs). The origin of this regional cooling trend still remains elusive. Here we demonstrate that the remote impact of Atlantic SST anomalies, as well as local atmosphere-ocean interactions, contributed to the eastern Pacific cooling during this period. By assimilating observed three-dimensional Atlantic temperature and salinity anomalies into a coupled general circulation model, we are able to qualitatively reproduce the observed Pacific decadal trends of SST and sea level pressure (SLP), albeit with reduced amplitude. Although a major part of the Pacific SLP trend can be explained by equatorial Pacific SST forcing only, the origin of this low-frequency variability can be traced back further to the remote impacts of equatorial Atlantic and South Atlantic SST trends. Atlantic SST impacts on the atmospheric circulation can also be detected for the Northeastern Pacific, thus providing a linkage between Atlantic climate and Western North American drought conditions.

  17. Tree-ring temperature reconstructions for the northeastern United States from Chamaecyparis thyoides

    NASA Astrophysics Data System (ADS)

    Anchukaitis, K. J.; Pederson, N.; Pearl, J. K.; Donnelly, J. P.

    2014-12-01

    Over the last century, the northeastern United States has warmed by over 1C, with the region of strongest warming found in coastal Massachusetts, Connecticut, and Rhode Island. These states are amongst the fastest warming in the entire country and the region as a whole is also warming faster than the national average. While these records all appear exceptional in the context of the last century, it is not known how these compare on longer time scales, to potential preindustrial late Holocene warm epochs, and in the context of decadal-scale variability in regional climate. Here, we develop a January through August temperature reconstruction using three Chamaecyparis thyoides (Atlantic White Cedar) chronologies in Massachusetts and Maine. The chronologies show a strong winter-spring-summer temperature signal representative of temperature variability from southern New York to northeastern Maine. The reconstruction is skillful and tracks upwards temperature trends since the early 19th century, reproducing decadal scale variability associated with warming from the 1920s through 1940s, cooling in the region from the 1940s until the 1960s, and warming since that time. No year since at least the middle of the 19th century is as warm as the Janaury through August temperatures seen in the exceptionally warm 2012. Recent modeling experiments simulate a range of decadal warming trends for the northeastern United States that is slightly higher than the reconstructed and instrumental trends. Atlantic White Cedar holds the potential to develop multicentury temperature reconstructions from this heavily-populated region.

  18. Reorganization of the North Atlantic Oscillation during early Holocene deglaciation

    NASA Astrophysics Data System (ADS)

    Wassenburg, Jasper A.; Dietrich, Stephan; Fietzke, Jan; Fohlmeister, Jens; Jochum, Klaus Peter; Scholz, Denis; Richter, Detlev K.; Sabaoui, Abdellah; Spötl, Christoph; Lohmann, Gerrit; Andreae, Meinrat O.; Immenhauser, Adrian

    2016-08-01

    The North Atlantic Oscillation is the dominant atmospheric pressure mode in the North Atlantic region and affects winter temperature and precipitation in the Mediterranean, northwest Europe, Greenland, and Asia. The index that describes the sea-level pressure difference between Iceland and the Azores is correlated with a dipole precipitation pattern over northwest Europe and northwest Africa. How the North Atlantic Oscillation will develop as the Greenland ice sheet melts is unclear. A potential past analogue is the early Holocene, during which melting ice sheets around the North Atlantic freshened surface waters, affecting the strength of the meridional overturning circulation. Here we present a Holocene rainfall record from northwest Africa based on speleothem δ18O and compare it against a speleothem-based rainfall record from Europe. The two records are positively correlated during the early Holocene, followed by a shift to an anti-correlation, similar to the modern record, during the mid-Holocene. On the basis of our simulations with an Earth system model, we suggest the shift to the anti-correlation reflects a large-scale atmospheric and oceanic reorganization in response to the demise of the Laurentide ice sheet and a strong reduction of meltwater flux to the North Atlantic, pointing to a potential sensitivity of the North Atlantic Oscillation to the melting of ice sheets.

  19. Student Opinion Surveys at Northeastern University.

    ERIC Educational Resources Information Center

    Bajdek, Anthony J.; Kim, Sungwoo

    1999-01-01

    Presents the 15-year story of the student affairs research operation at Northeastern University, covering the initial buildup, the demise due to institutional downsizing, and the resurrection. (Author)

  20. Central Atlantic Magmatic Province (CAMP): The Palisade Sill Connection

    NASA Astrophysics Data System (ADS)

    Ghatak, A.; Basu, A. R.

    2012-12-01

    The extensively studied 200Ma Central Atlantic Magmatic Province (CAMP) is considered to be the world's largest continental Large Igneous Province (LIP) covering up to 7 X 106 km2. This igneous province has been linked to the ~200Ma Mesozoic opening of the Central Atlantic Ocean. This opening fragmented the CAMP into several segments that occur on four different tectonic plates today. The CAMP related LIP is different from others in that it constitutes almost entirely of dikes and sills with sparse volcanic outflows. The 200 Ma Palisade Sill, exposed along the Hudson River in northeastern North America is an expression of the CAMP magmatism. On the basis of similar ages of eruption, Palisade Sill tholeiites have been correlated to other CAMP exposures in four continents. We provide an isotopic tracer study of the Palisade Sill basalts and relate them to low-Ti (<2 wt %) CAMP related tholeiites from North and South America, western Europe, and West Africa. We report Nd-Sr-Pb isotopic and multiple trace element data of 19 basalts and gabbros, 3 chilled margin basalts, and 4 sandstones spanning the entire length and thickness of the Palisade Sill in New York and New Jersey. These geochemical data are essential to understand the relationship between mantle geodynamic processes involved in the generation of the CAMP tholeiites prior to the formation of the of the Atlantic Ocean crust. The Palisade Sill basalts of this study yield the typical composition of low-Ti CAMP tholeiites with small LREE enrichments (LaN/SmN = 1.7 to 2.3), radiogenic Sr and negative ɛNd(I) values (87Sr/87Sr(I) = 0.70668 to 0.71037; ɛNd(I) = -0.64 to -3.8), and Pb-isotopic ratios (e.g. 206Pb/204Pb = 18.11 to 18.69) above the NHRL and subparallel to it. These geochemical data indicate the Palisade Sill basalts were derived from a slightly enriched OIB-like mantle source. Further, these rocks were derived by ~15% melting of a slightly depleted spinel peridotite with up to 20% contamination by the

  1. The North Atlantic Oscillation: Past, present, and future

    PubMed Central

    Visbeck, Martin H.; Hurrell, James W.; Polvani, Lorenzo; Cullen, Heidi M.

    2001-01-01

    The climate of the Atlantic sector exhibits considerable variability on a wide range of time scales. A substantial portion is associated with the North Atlantic Oscillation (NAO), a hemispheric meridional oscillation in atmospheric mass with centers of action near Iceland and over the subtropical Atlantic. NAO-related impacts on winter climate extend from Florida to Greenland and from northwestern Africa over Europe far into northern Asia. Over the last 3 decades, the phase of the NAO has been shifting from mostly negative to mostly positive index values. Much remains to be learned about the mechanisms that produce such low frequency changes in the North Atlantic climate, but it seems increasingly likely that human activities are playing a significant role. PMID:11687629

  2. High Diversity of Drosophilidae in High-Altitude Wet Forests in Northeastern Brazil.

    PubMed

    Monteiro, L S; Garcia, A C L; Oliveira, G F; Rohde, C

    2016-06-01

    The high-altitude wet forests of northeastern Brazil, locally known as "Brejos de Altitude," are enclaves of the Atlantic Forest situated above 500 m, surrounded by dryland vegetation, the Caatinga. The aim of this study was to characterize drosophilid communities in these upland forests, since few ecological studies on drosophilid communities have been conducted in northeastern Brazil. Four sites were investigated in three different times of the year throughout standardized traps. The results reveal the presence of 55 different species in a total of 13,064 specimens collected. The data were evaluated using ecological diversity measurements and compared with those obtained for other environments in the same geographic region. As for species composition, the Bonito upland forest, in a boundary forest location, stood out as having high species richness. PMID:26957082

  3. Pasture plants of the Northeastern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Temperate humid grazing lands are an important component of the landscape of the northeastern Unites States, as well as of the economy of this region, yet unlike their European counterparts, little is known about their basic ecology. During an eight-year survey of 44 farms across the northeastern Un...

  4. Pasture Plants of the Northeastern United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This factsheet contains summary information about the most common plant species encountered in northeastern pastures. Some information, such as plant size and flowering time, comes from standard reference works. Information on frequency and abundance in northeastern pastures is derived from an eight...

  5. Atlantic reef fish biogeography and evolution

    USGS Publications Warehouse

    Floeter, S.R.; Rocha, L.A.; Robertson, D.R.; Joyeux, J.C.; Smith-Vaniz, W.F.; Wirtz, P.; Edwards, A.J.; Barreiros, J.P.; Ferreira, C.E.L.; Gasparini, J.L.; Brito, A.; Falcon, J.M.; Bowen, B.W.; Bernardi, G.

    2008-01-01

    Aim: To understand why and when areas of endemism (provinces) of the tropical Atlantic Ocean were formed, how they relate to each other, and what processes have contributed to faunal enrichment. Location: Atlantic Ocean. Methods: The distributions of 2605 species of reef fishes were compiled for 25 areas of the Atlantic and southern Africa. Maximum-parsimony and distance analyses were employed to investigate biogeographical relationships among those areas. A collection of 26 phylogenies of various Atlantic reef fish taxa was used to assess patterns of origin and diversification relative to evolutionary scenarios based on spatio-temporal sequences of species splitting produced by geological and palaeoceanographic events. We present data on faunal (species and genera) richness, endemism patterns, diversity buildup (i.e. speciation processes), and evaluate the operation of the main biogeographical barriers and/or filters. Results: Phylogenetic (proportion of sister species) and distributional (number of shared species) patterns are generally concordant with recognized biogeographical provinces in the Atlantic. The highly uneven distribution of species in certain genera appears to be related to their origin, with highest species richness in areas with the greatest phylogenetic depth. Diversity buildup in Atlantic reef fishes involved (1) diversification within each province, (2) isolation as a result of biogeographical barriers, and (3) stochastic accretion by means of dispersal between provinces. The timing of divergence events is not concordant among taxonomic groups. The three soft (non-terrestrial) inter-regional barriers (mid-Atlantic, Amazon, and Benguela) clearly act as 'filters' by restricting dispersal but at the same time allowing occasional crossings that apparently lead to the establishment of new populations and species. Fluctuations in the effectiveness of the filters, combined with ecological differences among provinces, apparently provide a mechanism

  6. DEVELOPMENT OF A MID-ATLANTIC LAND USE/ LAND COVER CHANGE DATA SET (1970S TO 1990S)

    EPA Science Inventory

    The Mid-Atlantic region (MAIA) is comprised of southern New York, southern and western New Jersey, Pennsylvania, West Virginia, Maryland, Virginia, northeastern North Carolina, Delaware, and Washington, D.C. in the lower-48 American States. It is an ecosystem rich in streams, wet...

  7. Two new species of Aulospongus Norman, 1878 with a key to the Atlantic species (Poecilosclerida; Demospongiae; Porifera).

    PubMed

    Cavalcanti, Thaynã; Santos, George Garcia; Pinheiro, Ulisses

    2014-01-01

    We describe two new species: Aulospongus trirhabdostylus sp. nov. and Aulospongus mandela sp. nov. from Potiguar Basin (Rio Grande do Norte State, Northeastern Brazil). Both species were compared with their congeners and an identification key for the Atlantic species of Aulospongus is provided. The genus Aulospongus now contains 16 species. PMID:25081159

  8. South Africa, Namibia, and Botswana

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Pale green vegetation and red-brown deserts dominate this MODIS image of Namibia (left), Botswana (upper right), and the Republic of South Africa (bottom) acquired on June3, 2002. In central Namibia the mountainous terrain of Namaqualand is sandwiched between the Namib Desert on the Atlantic Coast and the Kalahari Desert to the interior, where white dots mark the location of small, impermanent lakes and ponds. Namaqualand is home to numerous rare succulent plants that can survive on the region.s scant rainfall as well as fog that blows in off the ocean. Namaqualand extends south of the Orange River, which runs along the border of Namibia and South Africa and into that country.s Northern Cape region. The Orange River extends almost all the way back through the country, and where it makes a sharp southward dip in this image (at lower right), it runs through the Asbestos Mountains, names for the naturally-occurring asbestos they contain. In southwestern South Africa, high plateaus, such as the Great Karoo become mountain ridges near the coast, and the city of Cape Town is visible as a grayish area of pixels on the north shores of the horseshoe-shaped False Bay at the Cape of Good Hope. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  9. Phanerozoic geological evolution of Northern and Central Africa: An overview

    NASA Astrophysics Data System (ADS)

    Guiraud, R.; Bosworth, W.; Thierry, J.; Delplanque, A.

    2005-10-01

    West African Craton (end Early Cambrian) and during the polyphased Hercynian-Variscan Orogeny that extended the final closure of the Paleotethys Ocean and resulted in the formation of the Maghrebian and Mauritanides belts. Only gentle deformation affected central and northeastern African during the Paleozoic, the latter remaining a passive margin of the Paleotethys Ocean up to the Early Permian when the development of the Neotethys initiated along the Eastern Mediterranean Basins. The Mesozoic-Cenozoic sedimentary sequence similarly consists of a succession of eustatically and tectonically controlled depositional cycles. Through time, progressive southwards shift of the basin margins occurred, related to the opening of the Neotethys Ocean and to the transgressions resulting from warming of the global climate and associated rise of the global sea level. The Guinean-Nigerian Shield, the Hoggar, Tibesti-Central Cyrenaica, Nubia, western Saudi Arabia, Central African Republic, and other long-lived arches delimited the principal basins. The main tectonic events were the polyphased extension, inversion, and folding of the northern African-Arabian shelf margin resulting in the development of the Alpine Maghrebian and Syrian Arc belts, rifting and drifting along the Central Atlantic, Somali Basins, and Gulf of Aden-Red Sea domains, inversion of the Murzuq-Djado Basin, and rifting and partial inversion along the Central African Rift System. Two major compressional events occurred in the Late Santonian and early Late Eocene. The former entailed folding and strike-slip faulting along the northeastern African-northern Arabian margin (Syrian Arc) and the Central African Fold Belt System (from Benue to Ogaden), and thrusting in Oman. The latter ("Pyrenean-Atlasic") resulted in folding, thrusting, and local metamorphism of the northern African-Arabian plate margin, and rejuvenation of intra-plate fault zones. Minor or more localized compressional deformations took place in the end

  10. Regional geologic framework off northeastern United States

    USGS Publications Warehouse

    Schlee, J.; Behrendt, John C.; Grow, J.A.; Robb, James M.; Mattick, R.; Taylor, P.T.; Lawson, B.J.

    1976-01-01

    Six multichannel seismic-reflection profiles taken across the Atlantic continental margin Previous HitoffTop the northeastern United States show an excess of 14 km of presumed Mesozoic and younger sedimentary rocks in the Baltimore Canyon trough and 8 km in the Georges Bank basin. Beneath the continental rise, the sedimentary prism thickness exceeds 7 km south of New Jersey and Maryland, and it is 4.5 km thick south of Georges Bank. Stratigraphically, the continental slope--outer edge of the continental shelf is a transition zone of high-velocity sedimentary rock, probably carbonate, that covers deeply subsided basement. Acoustically, the sedimentary sequence beneath the shelf is divided into three units which are correlated speculatively with the Cenozoic, the Cretaceous, and the Jurassic-Triassic sections. These units thicken offshore, and some have increased seismic velocities farther offshore. The uppermost unit thickens from a fraction of a kilometer to slightly more than a kilometer in a seaward direction, and velocity values range from 1.7 to 2.2 km/sec. The middle unit thickens from a fraction of a kilometer to as much as 5 km (northern Baltimore Canyon trough), and seismic velocity ranges from 2.2 to 5.4 km/sec. The lowest unit thickens to a maximum of 9 km (northern Baltimore Canyon), and velocities span the 3.9 to 5.9-km/sec interval. The spatial separation of magnetic and gravity anomalies on line 2 (New Jersey) suggests that in the Baltimore Canyon region the magnetic-slope anomaly is due to edge effects and that the previously reported free-air and isostatic gravity anomalies over the outer shelf may be due in part to a lateral increase in sediment density (velocity) near the shelf edge. The East Coast magnetic anomaly and the free-air gravity high both coincide over the outer shelf edge on line 1 (Georges Bank) but are offset by 20 km from the ridge on the reflection profile. Because the magnetic-slope-anomaly wavelength is nearly 50 km across, a

  11. Disease exchange across the tropical Atlantic.

    PubMed

    Curtin, P D

    1993-01-01

    The fifteenth-century encounter between previously separate disease environments was not simply an encounter between Europe and the Americas. It was preceded by an encounter between Europe and tropical Africa and followed by a still-more-intense transmission of diseases across the tropical Atlantic, mainly from Africa to the Americas. This transmission principally involved smallpox, yaws, yellow fever, and falciparum malaria. Many other vector-borne diseases failed to make the transfer for lack of suitable vectors in the Americas. The African diseases contributed even more than those from Europe to the depopulation of the humid tropics in the Americas. They also set up conditions that made residence in the tropical Americas dangerous for newly arrived people from Europe. PMID:7529931

  12. Assessment of simulated rainfall and temperature from the regional climate model REMO and future changes over Central Africa

    NASA Astrophysics Data System (ADS)

    Fotso-Nguemo, Thierry C.; Vondou, Derbetini A.; Tchawoua, Clément; Haensler, Andreas

    2016-07-01

    This work investigates spatial and temporal changes in rainfall and temperature over Central Africa, using historical and representative concentration pathways (RCP2.6, RCP4.5 and RCP8.5) of the regional climate model REMO forced by two general climate models: the Europe-wide Consortium Earth System Model (EC-Earth) and the Max Planck Institute-Earth System Model (MPI-ESM). We found that in the present period (1980-2005), the spatial distribution of rainfall is simulated with an annual spatial pattern correlation coefficient (PCC) of 0.76 for REMO driven by EC-Earth and 0.74 for REMO driven by MPI-ESM respectively when compared to CRU data. In terms of temperature, the annual PCC is 0.93 for the two REMO outputs. According to the climatology of Central Africa, we subdivided the study area into five sub-regions, we also noticed that the annual and seasonal PCC depend on the considered sub-region. For the future period (2070-2095), temperature is projected to increase following all the three scenarios. The rainfall amount is projected to decrease by up to 5 mm/day towards the end of the twenty first century under RCP8.5 scenario, and by 1-2 mm/day under RCP4.5 and RCP2.6 scenarios over Equatorial Guinea, Gabon, Congo, north-western Democratic Republic of Congo (DRC) and the Lake Victoria. Significant decrease is predicted to occur mostly in the northern part of the domain under RCP8.5 scenario. However, future rainfall over High Lands of Cameroon, Adamawa Plateau, north-eastern DRC and Atlantic Ocean is projected to increase.

  13. The African diaspora: mitochondrial DNA and the Atlantic slave trade.

    PubMed

    Salas, Antonio; Richards, Martin; Lareu, María-Victoria; Scozzari, Rosaria; Coppa, Alfredo; Torroni, Antonio; Macaulay, Vincent; Carracedo, Angel

    2004-03-01

    Between the 15th and 19th centuries ad, the Atlantic slave trade resulted in the forced movement of approximately 13 million people from Africa, mainly to the Americas. Only approximately 11 million survived the passage, and many more died in the early years of captivity. We have studied 481 mitochondrial DNAs (mtDNAs) of recent African ancestry in the Americas and in Eurasia, in an attempt to trace them back to particular regions of Africa. Our results show that mtDNAs in America and Eurasia can, in many cases, be traced to broad geographical regions within Africa, largely in accordance with historical evidence, and raise the possibility that a greater resolution may be possible in the future. However, they also indicate that, at least for the moment, considerable caution is warranted when assessing claims to be able to trace the ancestry of particular lineages to a particular locality within modern-day Africa. PMID:14872407

  14. The African Diaspora: Mitochondrial DNA and the Atlantic Slave Trade

    PubMed Central

    Salas, Antonio; Richards, Martin; Lareu, María-Victoria; Scozzari, Rosaria; Coppa, Alfredo; Torroni, Antonio; Macaulay, Vincent; Carracedo, Ángel

    2004-01-01

    Between the 15th and 19th centuries ad, the Atlantic slave trade resulted in the forced movement of ∼13 million people from Africa, mainly to the Americas. Only ∼11 million survived the passage, and many more died in the early years of captivity. We have studied 481 mitochondrial DNAs (mtDNAs) of recent African ancestry in the Americas and in Eurasia, in an attempt to trace them back to particular regions of Africa. Our results show that mtDNAs in America and Eurasia can, in many cases, be traced to broad geographical regions within Africa, largely in accordance with historical evidence, and raise the possibility that a greater resolution may be possible in the future. However, they also indicate that, at least for the moment, considerable caution is warranted when assessing claims to be able to trace the ancestry of particular lineages to a particular locality within modern-day Africa. PMID:14872407

  15. Pacific and Atlantic Ocean influences on multidecadal drought frequency in the United States

    USGS Publications Warehouse

    McCabe, G.J.; Palecki, M.A.; Betancourt, J.L.

    2004-01-01

    More than half (52%) of the spatial and temporal variance in multidecadal drought frequency over the conterminous United States is attributable to the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). An additional 22% of the variance in drought frequency is related to a complex spatial pattern of positive and negative trends in drought occurrence possibly related to increasing Northern Hemisphere temperatures or some other unidirectional climate trend. Recent droughts with broad impacts over the conterminous U.S. (1996, 1999-2002) were associated with North Atlantic warming (positive AMO) and north-eastern and tropical Pacific cooling (negative PDO). Much of the long-term predictability of drought frequency may reside in the multidecadal behavior of the North Atlantic Ocean. Should the current positive AMO (warm North Atlantic) conditions persist into the upcoming decade, we suggest two possible drought scenarios that resemble the continental-scale patterns of the 1930s (positive PDO) and 1950s (negative PDO) drought.

  16. Emissions from savanna fires in southern Africa

    NASA Astrophysics Data System (ADS)

    Sinha, Parikhit

    2004-12-01

    Airborne measurements are presented of emissions from savanna fires in southern Africa during the dry season. Measurements were obtained aboard the University of Washington Convair-580 research aircraft during the SAFARI 2000 field project in August and September 2000. Savanna fires in southern Africa emit a wide range of gaseous and particulate species including carbon, sulfur, nitrogen, halogen, and oxygenated compounds. Emission factors, emission ratios, and regional emissions of fifty trace gas and particulate species were derived, including eight species not previously reported in the literature (dimethyl sulfide, methyl nitrate, five species of hydrocarbons, and particles with diameters from 0.1--3 mum diameter). The physical, chemical, and radiative properties of the plume from a large savanna fire in South Africa are characterized, including plume dimensions, secondary formation of ozone and organic acids, oxidation of hydrocarbons, coagulation of particles, and gas-to-particle conversion in aged smoke. Numerous fires, thermodynamically stable layers aloft, and large-scale anticylonic flow result in high concentrations of air pollution distributed throughout the lower troposphere over southern Africa during the dry season. Average regional concentrations of CO (261 +/- 81 ppbv), SO2 (2.5 +/- 1.6 ppbv), O3 (64 +/- 13 ppbv), black particulate carbon (2.3 +/- 1.9 mug m-3), organic particulate carbon (6.2 +/- 5.2 mug m-3), total particle mass (26.0 +/- 4.7 mug m-3) are comparable to those found in polluted urban environments. The GEOS-CHEM model of tropospheric chemistry is used to characterize the transport of biomass burning emissions from southern Africa to the neighboring Atlantic and Indian Oceans during the dry season (May--October) of 2000. A large quantity of biomass burning emissions from southern Africa is transported westward over the latitudes 0--20°S to the southern Atlantic Ocean (˜40 Tg CO from May--October), contributing to a pollution anomaly

  17. South Africa.

    PubMed

    1985-05-01

    The 1983 population of South Africa was estimated at 31.1 million, with an annual growth rate of 2.5% (0.8% for whites, 1.8% for blacks and "coloreds," 1.8% for Asians, and 2.8% for Africans). The infant mortality rate was 14.9/1000 live births among whites, 80.6/1000 among blacks and coloreds, and 25.3/1000 among Asians. Life expectancy was 70 years for whites, 59 years for blacks and coloreds, 66 years for Asians, and 55 years for Africans. Racial discrimination has become increasingly institutionalized in South Africa since the ruling National Party came to power in 1948. The policy of apartheid calls for separate political institutions for the 4 major racial groups in the population. Africans are considered citizens of the homelands to which their tribal group is assigned, not permanent citizens of the country. Coloreds and Asians are considered citizens and given some political expression. The new political system envisions broad consensus among whites, coloreds, and Indians, and a parliamentary committee is considering possible abolition of laws against multiracial political activity. The work force totals 11 million, 30% of whom are engaged in agriculture, 29% are employed in industry and commerce, 34% work in the services sector, and 7% work in mining. The GNP in 1983 totalled US$75.5 billion and the GDP stood at US$73.2 billion. Per capita GNP was US$5239. PMID:12178120

  18. Roadside memorials in northeastern Thailand.

    PubMed

    Cohen, Erik

    In Thailand spirit houses are often established at places of fatal accidents, but these are generally anonymous. Personalized roadside memorials for accident victims are rare. This article analyses three roadside memorials, located on main roads in northeastern Thailand, in a comparative framework. Like in the contemporary West, such memorials commemorate a suddenly and violently killed person, but manifest a dynamics very different from that of Western roadside memorials: rather than private and temporary, these are permanent shrines, in which the spirit of the deceased is worshipped and supplicated by members of the public. The spirits and their shrines tend to become incorporated into the popular Thai magico-religious complex. While the literature offers a binary distinction between formal public monuments and informal, private and temporary (roadside) memorials, it is suggested that the informal, but public and permanent memorial shrines in Thailand exemplify a third type of edifices to commemorate the deceased in road accidents. PMID:23785985

  19. Regional nitrogen budgets and riverine N & P fluxes for the drainages to the North Atlantic Ocean: Natural and human influences

    USGS Publications Warehouse

    Howarth, R.W.; Billen, G.; Swaney, D.; Townsend, A.; Jaworski, N.; Lajtha, K.; Downing, J.A.; Elmgren, Ragnar; Caraco, N.; Jordan, T.; Berendse, F.; Freney, J.; Kudeyarov, V.; Murdoch, P.; Zhu, Z.-L.

    1996-01-01

    We present estimates of total nitrogen and total phosphorus fluxes in rivers to the North Atlantic Ocean from 14 regions in North America, South America, Europe, and Africa which collectively comprise the drainage basins to the North Atlantic. The Amazon basin dominates the overall phosphorus flux and has the highest phosphorus flux per area. The total nitrogen flux from the Amazon is also large, contributing 3.3 Tg yr-1 out of a total for the entire North Atlantic region of 13.1 Tg yr-1. On a per area basis, however, the largest nitrogen fluxes are found in the highly disturbed watersheds around the North Sea, in northwestern Europe, and in the northeastern U.S., all of which have riverine nitrogen fluxes greater than 1,000 kg N km-2 yr-1. Non-point sources of nitrogen dominate riverine fluxes to the coast in all regions. River fluxes of total nitrogen from the temperate regions of the North Atlantic basin are correlated with population density, as has been observed previously for fluxes of nitrate in the world's major rivers. However, more striking is a strong linear correlation between river fluxes of total nitrogen and the sum of anthropogenically-derived nitrogen inputs to the temperate regions (fertilizer application, human-induced increases in atmospheric deposition of oxidized forms of nitrogen, fixation by leguminous crops, and the import/export of nitrogen in agricultural products). On average, regional nitrogen fluxes in rivers are only 25% of these anthropogenically derived nitrogen inputs. Denitrification in wetlands and aquatic ecosystems is probably the dominant sink, with storage in forests perhaps also of importance. Storage of nitrogen in groundwater, although of importance in some localities, is a very small sink for nitrogen inputs in all regions. Agricultural sources of nitrogen dominate inputs in many regions, particularly the Mississippi basin and the North Sea drainages. Deposition of oxidized nitrogen, primarily of industrial origin, is the

  20. A hemispheric dust storm affecting the Atlantic and Mediterranean in April 1994: Analyses, modeling, ground-based measurements and satellite observations

    NASA Astrophysics Data System (ADS)

    Özsoy, Emin; Kubilay, Nilgün; Nickovic, Slobodan; Moulin, Cyril

    2001-08-01

    One of the largest recorded dust transport events originating from the great Sahara desert during April 1994 affected the entire region extending from the Caribbean to the Eurasian continent. This hemispherical transport of airborne dust took place during a series of storms that developed during the first three weeks of April in a background of low-index circulation. These repeated events are studied through the combined analyses and interpretation of atmospheric data, ground-based aerosol measurements, visibility observations, AVHRR and Meteosat visible band satellite data, and the results of Eta model simulations, including an aerosol transport component. The observations produce a consistent picture of the temporal and spatial development of the dust events, whose main features are used in parts to verify the model results. The rate of dust suspension from some areas of the western Sahara desert exceeded 1.5 mg m-2 h-1 and the maximum column integrated dust load reached 2 g m-2 during April 3-5 1994, when the first major suspension event produced two simultaneous pulses of dust moving in opposite directions across the subtropical Atlantic Ocean and the eastern Mediterranean Sea. These dust suspensions were created by surface winds resulting from subsidence on the northeastern side of a blocking anticyclone in the Atlantic region and subsequent winds of an intense developing cyclone in the Mediterranean-African region. In the following period, maximum dust loads of 4.5 and 2.5 g m-2 occurred on April 12 and 17, respectively, when new cyclones transported dust across the Mediterranean from Africa to Europe. The generation of the two dust pulses during the first even and the recurrent cyclone transport in the following period is shown to be the result of a large-scale, anomalous atmospheric circulation connected with blocking in the Atlantic Ocean and the interactions of upper air jets downstream of the blocking. The particular state of the hemispheric circulation

  1. 3. VIEW LOOKING NORTH WEST OVER CENTRAL ATLANTIC WITH ATLANTIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW LOOKING NORTH WEST OVER CENTRAL ATLANTIC WITH ATLANTIC OCEAN IN THE FOREGROUND. DENNIS HOTEL, BLENHEIM HOTEL, AND MARLBOROUGH HOTEL (LEFT TO RIGHT) ARE LOCATED IN THE CENTER OF THE PHOTOGRAPH. THE CLARIDGE HOTEL IS THE HIGHRISE IMMEDIATELY TO THE RIGHT OF THE MARLBOROUGH HOTEL - Marlborough, Blenheim & Dennis Hotels (aerial views), Between Park Place, Michigan Avenue & Boardwalk, Atlantic City, Atlantic County, NJ

  2. What would happen to Superstorm Sandy under the influence of a substantially warmer Atlantic Ocean?

    NASA Astrophysics Data System (ADS)

    Lau, William K. M.; Shi, J. J.; Tao, W. K.; Kim, K. M.

    2016-01-01

    Based on ensemble numerical simulations, we find that possible responses of Sandy-like superstorms under the influence of a substantially warmer Atlantic Ocean bifurcate into two groups. In the first group, storms are similar to present-day Sandy from genesis to extratropical transition, except they are much stronger, with peak Power Destructive Index (PDI) increased by 50-80%, heavy rain by 30-50%, and maximum storm size (MSS) approximately doubled. In the second group, storms amplify substantially over the interior of the Atlantic warm pool, with peak PDI increased by 100-160%, heavy rain by 70-180%, and MSS more than tripled compared to present-day Superstorm Sandy. These storms when exiting the warm pool, recurve northeastward out to sea, subsequently interact with the developing midlatitude storm by mutual counterclockwise rotation around each other and eventually amplify into a severe Northeastern coastal storm, making landfall over the extreme northeastern regions from Maine to Nova Scotia.

  3. Pb isotopes in surficial pelagic sediments from the North Atlantic

    NASA Technical Reports Server (NTRS)

    Hamelin, B.; Grousset, F.; Sholkovitz, E. R.

    1990-01-01

    The concentration of Pb and its isotopic composition were measured in samples from the surface of sea-water sediments obtained from the northeastern Atlantic, the Sargasso Sea, and the U.S. continental shelf, with the purpose of investigating changes in Pb sources due to the anthropogenic perturbation that took place in modern times. It was found that the anthropogenic Pb input to marine sediments due to the increase of Pb contamination over the ocean during the last century could be identified in all these samples. However, samples from eastern and western Atlantic had very different Pb isotopic profiles, each reflecting the character of anthropogenic Pb emissions from the European and U.S. industries, respectively.

  4. Restoring a Ruptured Relationship: Barnard College's Caryl Phillips' Senior English Seminar Focuses on Broken International Connections and Culminates with a Trans-Atlantic Journey

    ERIC Educational Resources Information Center

    Keels, Crystal L.

    2004-01-01

    Millions of African people who were captured, kidnapped and shackled for sale as part of the trans-Atlantic slave trade first passed through Cape Coast Castle in Ghana, West Africa. They stepped through the doorway that set them on a horrifying journey across the Atlantic Ocean. Men, women and children were taken by force, leaving their loved…

  5. Upper-level circulation in the South Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Peterson, Ray G.; Stramma, Lothar

    In this paper we present a literature survey of the South Atlantic's climate and its oceanic upper-layer circulation and meridional heat transport. The opening section deals with climate and is focused upon those elements having greatest oceanic relevance, i.e., distributions of atmospheric sea level pressure, the wind fields they produce, and the net surface energy fluxes. The various geostrophic currents comprising the upper-level general circulation are then reviewed in a manner organized around the subtropical gyre, beginning off southern Africa with the Agulhas Current Retroflection and then progressing to the Benguela Current, the equatorial current system and circulation in the Angola Basin, the large-scale variability adn interannual warmings at low latitudes, the Brazil Current, the South Atlantic Current, and finally to the Antarctic Circumpolar Current system in which the Falkland (Malvinas) Current is included. A summary of estimates of the meridional heat transport at various latitudes in the South Atlantic ends the survey.

  6. Relation between the wind stress curl in the North Atlantic and the Atlantic inflow to the Nordic Seas

    NASA Astrophysics Data System (ADS)

    Sandø, A. B.; Furevik, T.

    2008-06-01

    In this study an isopycnic coordinate ocean model has been used to investigate the relationships between the North Atlantic wind stress curl (WSC) and the inflow of Atlantic water to the Nordic Seas. For the period 1995-2001, there is a maximum in the correlation between the zonally averaged WSC at 55°N and the inflow with a 15-month time lag, capturing a relation already found in observational data. In the model this relation is linked to the mixing along the western flank of the Rockall Bank (56°N, 15°W). For the period 1995-2001 the atmospheric forcing in the northeastern North Atlantic is relatively weak, and the depth of the mixed layer is shallower than the sill depths of the Greenland-Scotland Ridge (GSR). Slowly moving, baroclinic disturbances caused by anomalies in the wind forcing will then be transmitted into the Nordic Seas where they are recorded as anomalous volume transports in the Norwegian Atlantic Current. In contrast, for the pentad prior to this period the atmospheric forcing is much more intense, and generates mixing well below sill depths of the GSR for all winters. Baroclinic disturbances forced by variations in the atmospheric forcing will then tend to follow f/H contours that do not enter the Nordic Seas, and the 15-month lagged relations between the wind and the volume transports will vanish. Recent observational data support this view.

  7. O the Genesis of Anomalous SST and Rainfall Patterns Over the Tropical Atlantic Basin

    NASA Astrophysics Data System (ADS)

    Nobre, Paulo

    Empirical orthogonal functions (EOFs), correlation, and composite analyses are used to investigate the evolution of phenomena associated with sea surface temperature (SST) and rainfall variability over the tropical Atlantic. The most important findings in this research are as follows. 1. The well known droughts over northeastern Brazil (Nordeste) are a local manifestation of a much larger -scale anomalies pattern encompassing the whole equatorial Atlantic and Amazon region. 2. The large-scale dipole-like anomalous rainfall pattern over the equatorial Atlantic and Amazon in March, April, and May (MAM), which is the rainy season for Nordeste region, is a consequence of meridional displacements of the inter-tropical convergence zone (ITCZ). In particular, negative rainfall anomalies to the south of the equator during MAM are related to an early withdrawal of ITCZ towards the warm SST anomalies over the northern tropical Atlantic. Concurrent with the rainfall anomaly dipole, there are large-scale patterns of SST and wind stress over the tropical Atlantic Ocean which also show a prominent dipole-like structure. The dipole patterns of SST and surface wind stress are the most dominant mode of interannual variability. Weaker trade winds are associated with warmer SST; stronger trade winds with cooler SST. 3. The spatial structure of (dipole-like) anomalous SST, rainfall and surface wind stress during MAM are clearly a modulation of the annual cycle for that season. The similarity between the patterns of interannual variability and MAM seasonal anomalies (departure from the annual mean) is quite remarkable. 4. Previous work has suggested the direct influence of the El Nino/Southern Oscillation (ENSO) on the southern Atlantic. This study brings observational evidence that ENSO effect over the northern Atlantic may happen through teleconnection patterns into higher latitudes of the Northern Hemisphere. The teleconnection effects over the northern Atlantic are out of phase

  8. North Atlantic Oscillation records in Siberian tree rings

    NASA Astrophysics Data System (ADS)

    Sidorova, Olga; Saurer, Matthias; Siegwolf, Rolf

    2010-05-01

    Changes in the Eurasian subarctic like temperature increase, thawing of permafrost, changes in seasonality (shifting of the beginning of the growth period), and changes in the amount of precipitations are linked to a positive phase of North Atlantic Oscillation (NAO) in recent decades. We report about the response of larch trees to climatic changes in the eastern Taimyr (Central Siberia) and northeastern Yakutia (Eastern Siberia) at high latitudes during the last century using tree ring width, latewood density and stable isotope wood and cellulose (δ13C, δ18O) chronologies. Not only the summer months were related to the carbon and oxygen isotope variations. The positive relationship, which was found between February temperature and δ18O of cellulose for northeastern Yakutia and the negative correlations between the temperature of February and δ13C of wood and cellulose for eastern Taimyr, could be explained by the influence of North Atlantic Oscillation. This work was supported by Swiss National Science Foundation SNF 200021_121838/1 and RFBR_sibir 09-05-98015.

  9. New species and records of Anacroneuria (Plecoptera: Perlidae) from the northeastern semi-arid region of Brazil.

    PubMed

    Duarte, Tácio; Lecci, Lucas Silveira

    2016-01-01

    The genus Anacroneuria is widely distributed in the Neotropical Region. There are about 80 species listed from Brazil, five of which are recorded from the northeastern semi-arid region of Brazil, an area characterized by irregular and low precipitation. Examination of adult Anacroneuria material from this including areas of Caatinga desert vegetation and Atlantic forest revealed two new species records, A. debilis (Pictet) and A. terere Righi-Cavallaro & Lecci. Additionally, two new species, A. calori n. sp. and A. singela n. sp., are described from this material. These new records and new species reflect a major effort to document the biodiversity of the aquatic insects of the northeastern semi-arid region of Brazil by the Research Program in Semi-arid Biodiversity. PMID:27396007

  10. Oxygen Isotope Speleothem record of Decadal and Multidecadal Atlantic Oscillations over the last millennium in Southwestern Morocco

    NASA Astrophysics Data System (ADS)

    Ait Brahim, Yassine; Sha, LiJuan; Sifeddine, Abdelfettah; Cheng, Hai; Bouchaou, Lhoussaine; Da Cruz Junior, Francisco William; Khodri, Myriam; Peerbocus, Nawaaz; Mariller, Alexandre; Apaestegui, James; Guyot, Jean-Loup; Auler, Augusto; Hassane Beraaouz, El

    2016-04-01

    In this work, we present a stable oxygen isotope (δ18O) speleothem record from Ifoulki cave located South-West of Morocco (N 30°42'29'', W 09°19'39'' and 1267 meters above sea level). The age model, based on eighteen U-Th dates, reveals that the record covers the AD 790-1953 period with a data resolution of ~1.7 years. Stable oxygen isotope variations show substantial decadal to multi-decadal swings between dry and humid periods. The Medieval Climate Anomaly (MCA) is characterized by the longest period with δ18O values above the average, suggestive of pronounced drying possibly as a response to positive North Atlantic Oscillation (NAO) phases and increased volcanic activity during this period. However, at least two short wet phases are recognized during the MCA in Morocco, with peaks centered on the years AD 1040 and AD 1190 and seem to overlap with negative NAO phases as recorded in a recently published NAO reconstruction for the last millennium. During the next centuries, the NAO again depicts predominantly negative values and the δ18O drops below the average during the Little Ice Age (LIA). Furthermore, a striking resemblance is observed between our record and another recently published stalagmite record from the Piste cave in Northeastern Morocco, which is quite remarkable given the different type of tracers (δ18O vs. Mg and Sr) obtained from different environments (Western High Atlas vs. Northeastern Middle Atlas and ~634 km away). Comparison with regional paleorecords from other studies also reveals the replication of many characteristic climate features from the last millennium, first detected in Northern Morocco and the Iberian Peninsula. In particular, the evidence of generally dry conditions during the MCA and wetter conditions in the LIA, which is confirmed by all the paleorecords. These similarities indicate coherent climate variability in Northwest Africa and the Iberian Peninsula and suggest a strong regional control of the NAO during the last

  11. 76 FR 1153 - Atlantic Grid Operations A LLC, Atlantic Grid Operations B LLC, Atlantic Grid Operations C LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-07

    ... Energy Regulatory Commission Atlantic Grid Operations A LLC, Atlantic Grid Operations B LLC, Atlantic Grid Operations C LLC, Atlantic Grid Operations D LLC and Atlantic Grid Operations E LLC; Notice of... (Commission) Rules of Practice and Procedure, 18 CFR 385.207, and Order No. 679,\\1\\ Atlantic Grid Operations...

  12. Climate variability during the Holocene inferred from northeastern Iberian speleothems

    NASA Astrophysics Data System (ADS)

    Moreno, A.; Bartolomé, M.; Sancho, C.; Belmonte, Á.; Stoll, H.; Cacho, I.; Edwards, R. L.; Hellstrom, J.

    2012-04-01

    Although the general climate trends during the Holocene in the Iberian Peninsula have been well described after the study of marine and lacustrine records, many questions regarding the timing of some of the events together with the characterization of the higher-frequency climate variability are still poorly understood. New speleothem records from several caves in northeastern Iberia provide data to explore Holocene climate changes. The selected caves are located in a latitudinal transect from the Pyrenees to the Iberian Range and placed at different altitude. Two of them, 5 de Agosto and Pot au Feu, belong to the same karstic complex in Cotiella massif (Central Pyrenees, 1600 m asl). Seso Cave, also in the Central Pyrenees but at 781 m of altitude, and Molinos cave, a cavity very rich in speleothems located at 1040 m in the Iberian Range, complete the transect. Although in all the caves precipitation coming from Atlantic fronts dominates over the year, a significant Mediterranean influence, specially in summer months, is identified after rainfall monitoring. Speleothem formation during the Holocene occurred at a very low pace in 5 de Agosto cave (80yrs/mm) and increased dramatically at low-altitude caves and during particular periods proved to be wetter (eg. Early Holocene in Molinos cave, less than 10yr/mm). In Seso and Pot au Feu caves, up to seven studied speleothems only grew during short climatic events such as the Iron Cold Period (3000-2500 cal yr BP) or the Little Ice Age (1300-1850 yr AD) that, although cold, were particularly humid periods in northeastern Spain. First stable isotope results highlight the importance of comparing speleothems with similar growing rates and from the same cave to extract climate information and discard other influences. From the integration of four stalagmites from Molinos cave covering since the Holocene onset to 2000 cal yrs BP, the Early Holocene (11.7-8.5 ka BP) with d13C values between -11 and - 9‰ appears as the

  13. Africa: Prosperous times

    SciTech Connect

    1996-08-01

    Political instability and corruption is the rule, rather than the exception, in Africa`s main producing regions, but exploration and production prospects there are bright and attractive to foreign operators. The paper discusses exploration, drilling, resource development, and production in Nigeria, Libya, Algeria, Egypt, Angola, Congo, Gabon, and Tunisia. The other countries of Africa are briefly mentioned, i.e., Cameroon, Cote D`Ivoire, South Africa, Sudan, Namibia, Equatorial Guinea, Eritrea, Zaire, Mozambique, Ghana, Niger, and Seychelles.

  14. The Cretaceous opening of the South Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Granot, Roi; Dyment, Jérôme

    2015-03-01

    The separation of South America from Africa during the Cretaceous is poorly understood due to the long period of stable polarity of the geomagnetic field, the Cretaceous Normal Superchron (CNS, lasted between ∼121 and 83.6 Myr ago). We present a new identification of magnetic anomalies located within the southern South Atlantic magnetic quiet zones that have arisen due to past variations in the strength of the dipolar geomagnetic field. Using these anomalies, together with fracture zone locations, we calculate the first set of magnetic anomalies-based finite rotation parameters for South America and Africa during that period. The kinematic solutions are generally consistent with fracture zone traces and magnetic anomalies outside the area used to construct them. The rotations indicate that seafloor spreading rates increased steadily throughout most of the Cretaceous and decreased sharply at around 80 Myr ago. A change in plate motion took place in the middle of the superchron, roughly 100 Myr ago, around the time of the final breakup (i.e., separation of continental-oceanic boundary in the Equatorial Atlantic). Prominent misfit between the calculated synthetic flowlines (older than Anomaly Q1) and the fracture zones straddling the African Plate in the central South Atlantic could only be explained by a combination of seafloor asymmetry and internal dextral motion (<100 km) within South America, west of the Rio Grande fracture zone. This process has lasted until ∼92 Myr ago after which both Africa and South America (south of the equator) behaved rigidly. The clearing of the continental-oceanic boundaries within the Equatorial Atlantic Gateway was probably completed by ∼95 Myr ago. The clearing was followed by a progressive widening and deepening of the passageway, leading to the emergence of north-south flow of intermediate and deep-water which might have triggered the global cooling of bottom water and the end for the Cretaceous greenhouse period.

  15. Crustal structure of northeastern California

    NASA Astrophysics Data System (ADS)

    Zucca, John J.; Fuis, Gary S.; Milkereit, Bernd; Mooney, Walter D.; Catchings, Rufus D.

    1986-06-01

    In 1981, the U.S. Geological Survey conducted a seismic refraction survey of northeastern California designed to characterize the structure in four geologic provinces: the Klamath Mountains, Cascade Range, Modoc Plateau, and Basin and Range provinces. The survey consisted of north-south lines in the Klamath Mountains and Modoc Plateau provinces, northwest-southeast lines centered on Mount Shasta and Medicine Lake volcano, and an east-west line linking all the profiles. All lines except the east-west line ranged in length from 125 to 140 km, contained three shot points, and were recorded by 100 instruments. The east-west line was 260 km long, contained six shot points, and was recorded by 200 instruments. The Klamath and Modoc lines yielded the simplest models. The Klamath model is finely layered from the surface to at least 14-km depth, consisting of a series of high-velocity layers (6.1-6.7 km/s), ranging in thickness from 1 to 4 km, with alternating positive and negative velocity gradients. A layer with an unreversed velocity of 7.0 km/s extends from 14 km downward to an unknown depth. The Modoc model, in contrast, is thickly layered and has lower velocity at all depths down to 25 km. The uppermost layer, 4.5 km thick, consists of low-velocity material (2-4.5 km/s). Velocity beneath this layer is much higher (6.2 km/s) and increases slowly with depth. A small velocity step (to 6.4 km/s) is seen at 11 km, and a larger step (to 7.0 km/s) is seen at 25 km depth. Moho is probably 38-45 km deep under the Modoc Plateau, but its depth is unknown under the Klamath Mountains. Models for the Shasta and Medicine Lake lines show special features including low velocity (less than 3.5 km/s) in the edifice of Mount Shasta but high velocity (5.6 km/s) at shallow depth (1-2 km) under the summit of Medicine Lake volcano. The model for the east-west line consists of a western part similar to the Klamath model, an eastern part similar to the Modoc model, and laterally changing

  16. Phylogeographic analysis reveals a deep lineage split within North Atlantic Littorina saxatilis.

    PubMed

    Doellman, Meredith M; Trussell, Geoffrey C; Grahame, John W; Vollmer, Steve V

    2011-11-01

    Phylogeographic studies provide critical insight into the evolutionary histories of model organisms; yet, to date, range-wide data are lacking for the rough periwinkle Littorina saxatilis, a classic example of marine sympatric speciation. Here, we use mitochondrial DNA (mtDNA) sequence data to demonstrate that L. saxatilis is not monophyletic for this marker, but is composed of two distinct mtDNA lineages (I and II) that are shared with sister species Littorina arcana and Littorina compressa. Bayesian coalescent dating and phylogeographic patterns indicate that both L. saxatilis lineages originated in the eastern North Atlantic, around the British Isles, at approximately 0.64 Ma. Both lineages are now distributed broadly across the eastern, central and western North Atlantic, and show strong phylogeographic structure among regions. The Iberian Peninsula is genetically distinct, suggesting prolonged isolation from northeastern North Atlantic populations. Western North Atlantic populations of L. saxatilis lineages I and II predate the last glacial maximum and have been isolated from eastern North Atlantic populations since that time. This identification of two distinct, broadly distributed mtDNA lineages further complicates observed patterns of repeated incipient ecological speciation in L. saxatilis, because the sympatric origins of distinct ecotype pairs on eastern North Atlantic shores may be confounded by admixture of divergent lineages. PMID:21429920

  17. Regional paleogeographic evolution of west Africa: Implications for hydrocarbon exploration

    SciTech Connect

    Hempton, M.R.; Rosen, M.A.; Coughlin, R.M.; Scardina, A.D.; Hagen, E.S.; Nordstrom, P.J. )

    1991-03-01

    New paleogeographic reconstructions of west African continental margins provide a regional framework to contrast differences in hydrocarbon habitat and tectonostratigraphic style. Five regional provinces are delineated: (1) Northwest Africa margin from mauritania to Sierra Leone, (2) Transform margin from Liberia to Benin, (3) Niger delta of Nigeria, Cameroon, and Equatorial Guinea, (4) South Atlantic Salt basin margin from Cameroon to Angola, and (5) Southwest Africa margin of Namibia and South Africa. Computer-constrained paleogeographic reconstructions based on exploration data depict the separation of west Africa from South and North America during the Late Triassic to the present along three rift systems. In northwest Africa rifting began in the Late Triassic associated with the opening of the Central Atlantic. In southwest Africa rifting began between the southern tips of Africa and South America in the Early Cretaceous (Valanginian) and propagated northward to the Benue Trough, a broad zone of left-lateral shear and extensional basins that began to open in the Aptian. Between these two rift systems, the Transform margin rift system initiated in the Early Cretaceous (Barremain) as a wrench-fault dominated eastward extension of the Proto-Caribbean ocean that propagated to the Benue Trough by the middle Albian. The most important variables affecting the tectonostratigraphic and hydrocarbon evolution of the west African margins include (1) the geometry, kinematics, and duration of rifting; (2) distribution of rift basins relative to paleoclimate zones (which affects the deposition of lacustrine source rocks and evaporites while influencing the type and quantity of sediment derived from land); (3) sea-level fluctuations; and (4) distribution of deltaic and turbiditic depocenters.

  18. CHARCOAL-PRODUCING INDUSTRIES IN NORTHEASTERN BRAZIL

    EPA Science Inventory

    Charcoal workers in northeastern Brazil: Occupational risks and effects of exposure to wood smoke
    ABSTRACT
    Brazil has the largest production of charcoal in the world, which is used mostly in the iron and steel industries. In most of the production sites, the process is ba...

  19. Superintendent Communication Patterns in Northeastern Indiana

    ERIC Educational Resources Information Center

    Clendening, David Earl

    2009-01-01

    The purpose of the qualitative study was to examine the communication patterns of superintendents in Northeastern Indiana. The demand for accountability, transparency, and student achievement calls for today's superintendent to increase communication strategies and support the needs of the varied stakeholders. Today's public school leaders are…

  20. Chemical Dependency Regional Needs Assessment: Northeastern Minnesota.

    ERIC Educational Resources Information Center

    Stone, Marylee

    The Minnesota Model of Chemical Dependency Treatment, which evolved from a combination of the grassroots Alcoholics Anonymous movement and the State Mental Health Services in the 1960s has made Minnesota an international leader in chemical dependency treatment efforts. Northeastern Minnesota has shared this reputation with the state. In spite of…

  1. Fennerosquilla heptacantha (Crustacea: Stomatopoda: Squillidae) in South Atlantic Ocean.

    PubMed

    Lucatelli, Débora

    2015-01-01

    Fennerosquilla is a monotypic genus that belongs to the family Squillidae, which has the highest generic diversity within Stomatopoda. This genus has been recorded in the north Atlantic Ocean, the Gulf of Mexico and Caribbean Sea, between 105 and 458 m depth. The present specimen was collected during the project "Avaliação da Biota Bentônica e Planctônica na porção offshore das Bacias Potiguar e Ceará", in 2011, from the continental slope region of Brazil. In this expedition Fennerosquilla heptacantha was found at 178-193 m depth, and represents the first record of the species in the south Atlantic Ocean (Rio Grande do Norte State, northeastern Brazil), expanding the southern limit distribution. The specimen is the largest recorded, measuring 149 mm total length. The pigmentation zone on median region of telson and all diagnostic characters are still preserved and agree with the original description. Fennerosquilla heptacantha has a disjunct deep water distribution (more than 100 m) in the tropical western Atlantic, mostly along the continental slope. PMID:26624302

  2. Out of Africa and into an ice age: on the role of global climate change in the late Pleistocene migration of early modern humans out of Africa.

    PubMed

    Carto, Shannon L; Weaver, Andrew J; Hetherington, Renée; Lam, Yin; Wiebe, Edward C

    2009-02-01

    The results from two climate model simulations are used to explore the relationship between North Atlantic sea surface temperatures and the development of African aridity around 100,000 years ago. Through the use of illustrative simulations with an Earth System Climate Model, it is shown that freshwater fluxes associated with ice sheet surges into the North Atlantic, known as Heinrich events, lead to the southward shift of the intertropical convergence zone over Africa. This, combined with the overall increased aridity in the cooler mean climate, leads to substantial changes in simulated African vegetation cover, particularly in the Sahel. We suggest that Heinrich events, which occurred episodically throughout the last glacial cycle, led to abrupt changes in climate that may have rendered large parts of North, East, and West Africa unsuitable for hominin occupation, thus compelling early Homo sapiens to migrate out of Africa. PMID:19019409

  3. A new Crossodactylodes Cochran, 1938 (Anura: Leptodactylidae: Paratelmatobiinae) from the highlands of the Atlantic Forests of southern Bahia, Brazil.

    PubMed

    Teixeira, Mauro; Recoder, Renato Sousa; Amaro, Renata Cecília; Damasceno, Roberta Pacheco; Cassimiro, José; Rodrigues, Miguel Trefaut

    2013-01-01

    A new Crossodactylodes is described from Serra das Lontras, in the highlands of the Atlantic Forests of southern Bahia. The new species can be distinguished from all other Crossodactylodes by having Finger I ending in an acute tip, a larger body size, by cranial features, and by molecular data. Like their congeners, the new species live in bromeliads but is widely geographically disjunct, being apparently restricted to the summit of a mountain range in Northeastern Brazil. PMID:26146739

  4. Nitrogen in West Africa: the regional cycle

    SciTech Connect

    Robertson, G.P.; Rosswall, T.

    1986-03-01

    A nitrogen cycle budget has been calculated for West Africa south of the northern Sahara that quantifies biologically important pools of nitrogen in the region and major fluxes associated with these pools. Major compartments of the model include noncultivated systems broken down by vegetation zone, successional status, and plant components, annual and perennial crops each broken down by crop species and plant and harvest components; wetlands; anthropic systems, and soils and sediments. Base reference year is 1978. Biological nitrogen fixation and precipitation fluxes dominated nitrogen inputs to West Africa in 1978. Approximately 12 x 10/sup 9/ kg were fixed in noncultivated systems; about half of this was fixed in early successional (0-6 yr) rain forests, and much of the rest in grazed or fallow savanna grasslands and woodlands. Less than 0.7 x 10/sup 9/ kg were fixed in cultivated systems; legumes accounted for approx. = 25% of this. Total anthropic sources (fossil fuel combustion, fertilizer production, and agricultural commodity imports) were minor (< 0.3 x 10/sup 9/ kg). Precipitation inputs to the region were approx. = 0.4 x 10/sup 9/ kg. Most nitrogen leaving West Africa did so volatilized by fire (approx. = 8.3 x 10/sup 9/ kg), principally in non-cropped systems. Major losses also occurred via hydrologic export to the Atlantic Ocean (1.5 x 10/sup 9/ kg) and via denitrification (1.1 x 10/sup 9/ kg). Total N losses from West Africa exceeded 11.0 x 10/sup 9/ kg. The overall budget balances within 1%, despite independent calculations of all major fluxes. The balance portrays a nitrogen cycle dominated by pools and fluxes in noncropped systems. Indirect human influences, however, mainly through effects on vegetation cover, appear to be a major determinant of both the rates at which nitrogen is cycled in West Africa and the relative importance of most pools and fluxes.

  5. Atlantic City memories.

    PubMed

    Epstein, Franklin H

    2008-04-01

    Fifty years ago, the Atlantic City meetings, held the first week in May of every year, were attended by all the elite of American academic medicine and all who wanted to join that group. Part of the magic of those meetings was that professors and neophytes took each other seriously and talked to each other. PMID:18382726

  6. [[History of Community Health in Africa. The Swiss Medical Missionaries' Endeavour in South Africa].

    PubMed

    Mabika, Hines

    2015-01-01

    It was not Dutch settlers nor British colonizers who introduced public and community health practice in north-eastern South Africa but medical doctors of the Swiss mission in southern Africa. While the history of medical knowledge transfer into 19th-20th century Africa emphasises colonial powers, this paper shows how countries without colonies contributed to expand western medical cultures, including public health. The Swiss took advantage of the local authorities' negligence, and implemented their own model of medicalization of African societies, understood as the way of improving health standards. They moved from a tolerated hospital-centred medicine to the practice of community health, which was uncommon at the time. Elim hospital's physicians moved back boundaries of segregationist policies, and sometime gave the impression of being involved in the political struggle against Apartheid. Thus, Swiss public health activities could later be seen as sorts of seeds that were planted and would partly reappear in 1994 with the ANC-projected national health policy. PMID:26403059

  7. Atlantic tropical cyclones revisited

    NASA Astrophysics Data System (ADS)

    Mann, Michael E.; Emanuel, Kerry A.; Holland, Greg J.; Webster, Peter J.

    Vigorous discussions have taken place recently in Eos [e.g., Mann and Emanuel, 2006; Landsea, 2007] and elsewhere [Emanuel, 2005; Webster et al., 2005; Hoyos et al., 2006; Trenberth and Shea, 2006; Kossin et al., 2007] regarding trends in North Atlantic tropical cyclone (TC) activity and their potential connection with anthropogenic climate change. In one study, for example [Landsea, 2007], it is argued that a substantial underestimate of Atlantic tropical cyclone counts in earlier decades arising from insufficient observing systems invalidates the conclusion that trends in TC behavior may be connected to climate change. Here we argue that such connections are in fact robust with respect to uncertainties in earlier observations.Several recent studies have investigated trends in various measures of TC activity. Emanuel [2005] showed that a measure of total power dissipation by TCs (the power dissipation index, or PDI) is highly correlated with August-October sea surface temperatures (SST) over the main development region (MDR) for Atlantic TCs over at least the past half century. Some support for this conclusion was provided by Sriver and Ruber [2006]. Webster et al. [2005] demonstrated a statistically significant increase in recent decades in both the total number of the strongest category cyclones (categories 4 and 5) and the proportion of storms reaching hurricane intensity. Hoyos et al. [2006] showed that these increases were closely tied to warming trends in tropical Atlantic SST, while, for example, the modest decrease in vertical wind shear played a more secondary role. Kossin et al. [2007] called into question some trends in other basins, based on a reanalysis of past TC data, but they found the North Atlantic trends to be robust.

  8. Large Holocene summer temperature oscillations and impact on the peopling of the northeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Hou, Juzhi; Huang, Yongsong; Zhao, Jiangtao; Liu, Zhonghui; Colman, Steve; An, Zhisheng

    2016-02-01

    Summer temperatures on the Tibetan Plateau (TP) significantly affect stability of glaciers that provide steady water resources to nearly half of the world population. However, lack of reliable, long-term proxy records greatly impedes understanding of regional temperature sensitivity to climate forcings. Here we present a 16 ka long, alkenone-based summer temperature record from Lake Qinghai, northeastern TP that demonstrates major regional temperature response to changes in summer insolation and Atlantic Meridional Overturning Circulation during the Holocene and late glacial. Importantly, we find a period of sustained summer temperature decline (>4°C) between 5 and 3.5 ka, which coincides with expansion of Barents Sea ice coverage and is likely driven by intensification of the Westerlies. This unusually long and pronounced regional cooling event likely delayed permanent human settlements on the high-altitude regions (>3000 m) of the TP by at least 500 years.

  9. Commonalities in Mercury Behavior in Contrasting Northeastern USA Landscapes

    NASA Astrophysics Data System (ADS)

    Shanley, J. B.; Scherbatskoy, T.; Schuster, P. F.; Reddy, M. M.; Chalmers, A.

    2001-05-01

    Generally less than 20% of atmospherically deposited mercury is exported from watersheds in streamflow, but the mercury export that does occur is highly episodic. Our research from diverse landscapes in northern New England, including small forested, agricultural, and urban watersheds as well as some larger rivers discharging to Lake Champlain and the Atlantic Ocean, indicates a consistent positive correlation between Hg concentrations and stream discharge. This relation appears to be driven by increased DOC, POC, and suspended sediment concentrations at increased streamflow. Streamwater Hg analyses pooled from 10 watersheds of diverse size and land use during the 2000 snowmelt within the Sleepers River Research Watershed in northeastern Vermont displayed a high correlation between (1) dissolved Hg and DOC, and (2) particulate Hg and POC. The same correlations held at Nettle Brook, a forested Vermont watershed 100 km west of Sleepers River. At Nettle Brook, DOC and dissolved mercury concentrations were both greater than at Sleepers River but the relation at the two sites was co-linear. In an agricultural watershed in northwestern Vermont, particulate Hg concentrations in streamflow were comparable to those at Nettle Brook despite markedly higher suspended sediment (and presumably POC) concentrations, suggesting the soil Hg pool is depleted by more frequent erosional events. The coupling of organic carbon with mercury may originate in the shallow soil zone; high concentrations of DOC and dissolved Hg were observed in O-horizon soil solution both at Nettle Brook and at some sites in the Adirondack Mountains of New York. Our findings underscore the importance of sampling during high-flow to determine accurate fluxes of Hg in streamflow. It is not clear, however, whether organic carbon actually controls Hg mobility, or whether organic carbon and Hg move in tandem simply as a result of their common source in soil organic matter.

  10. 75 FR 35435 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-22

    ... crab emergency action implemented by NMFS (74 FR 9770, March 6, 2009), i.e., a target TAC of 3.56..., 2010 final rule implementing the FY 2010 red crab specifications (75 FR 27219), that rule set the... catch (TAC) and a fleet-wide days-at-sea (DAS) allocation. However, the implementing regulations for...

  11. What role does crustal heterogeneity play on continental break-up; the interplay of a foldbelt, rift system and ocean basin in the South Atlantic

    NASA Astrophysics Data System (ADS)

    Paton, Douglas; Mortimer, Estelle; Hodgson, Neil

    2015-04-01

    Although extensively studied, two key questions remain unanswered regarding the evolution of the southern South Atlantic. Firstly, where is the Cape Foldbelt (CFB) in offshore South Africa? The CFB is part of the broader Gonwanian Orogeny that prior to South Atlantic rifting continued into the Ventana Foldbelt of Argentina but to date its location in the offshore part of South Africa remains enigmatic. Secondly, the conjugate rift basin to South Africa is the Colorado Basin in Argentina but why does it trend east-west despite its perpendicular orientation to the Atlantic spreading ridge? Current plate models and structural understands cannot explain these fundamental questions. We use newly acquired deep reflection seismic data in the Orange Basin, South Africa, to develop a new structural model for the southern South Atlantic. We characterise the geometry of the Cape Foldbelt onshore and for the first time correlate it into the offshore. We show that it has a north-south trend immediately to the north of the Cape Peninsula but then has a syntaxis (Garies syntaxis) that results in a change to an east-west orientation. This forms the missing jigsaw piece of the Atlantic reconstruction as this is directly beside the restored Colorado Basin. When considered within the pre-break up structural configuration our observations imply that prior to the main phase of Atlantic rifting in the Mezosoic there was significant variation in crustal geometry incorporating the Orange Basin of South Africa, the Colorado Basin and the Gariep Belt of Namibia. These faults were active during Gondwana rifting, but the Colorado rift failed resulting in the present day location of the South Atlantic. Not only do our results improve our understanding of the evolution of the South Atlantic ocean, they highlight the importance of differentiating between early rift evolution and strain localisation during the subsequent rift phase prior to seafloor spreading.

  12. Quaternary ecological and geomorphic changes associated with rainfall events in presently semi-arid northeastern Brazil

    NASA Astrophysics Data System (ADS)

    Auler, Augusto S.; Wang, Xianfeng; Edwards, R. Lawrence; Cheng, Hai; Cristalli, Patrícia S.; Smart, Peter L.; Richards, David A.

    2004-10-01

    Several geomorphic features and palaeobiotic remains in now semi-arid northeastern Brazil indicate major palaeoenvironmental changes during past periods of increased rainfall. 230Th mass spectrometric ages of speleothems and travertines have allowed the determination of the timing and duration of wetter than present conditions. The data demonstrate that wet events have occurred throughout much of the Pleistocene, present dry conditions having been established at the end of the Younger Dryas. A markedly different fauna comprising megafaunal elements not adapted to the present low arboreal scrubland caatinga vegetation existed in the area. Palaeobotanical remains embedded in travertine indicate forested vegetation at these wetter intervals, suggesting that the caatinga was then replaced or mixed with a semi-deciduous forest. Due to the abundance of travertine sites containing fossil botanical remains in northeastern Brazil, it is believed that forest expansion occurred over large areas of the now semi-arid zone, showing that the long hypothesised forested links between biodiversity-rich Amazon and Atlantic rainforests may indeed have existed during these moister phases. Copyright

  13. Arctic Vortex changes alter the sources and isotopic values of precipitation in northeastern US.

    PubMed

    Puntsag, Tamir; Mitchell, Myron J; Campbell, John L; Klein, Eric S; Likens, Gene E; Welker, Jeffrey M

    2016-01-01

    Altered atmospheric circulation, reductions in Arctic sea ice, ocean warming, and changes in evaporation and transpiration are driving changes in the global hydrologic cycle. Precipitation isotopic (δ(18)O and δ(2)H) measurements can help provide a mechanistic understanding of hydrologic change at global and regional scales. To study the changing water cycle in the northeastern US, we examined the longest (1968-2010) record of precipitation isotope values, collected at the Hubbard Brook Experimental Forest in New Hampshire, US (43(°)56'N, 71(°)45'W). We found a significant reduction in δ(18)O and δ(2)H values over the 43-year record, coupled with a significant increase in d-excess values. This gradual reduction in δ(18)O and δ(2)H values unexpectedly occurred during a period of regional warming. We provide evidence that these changes are governed by the interactions among the Atlantic Multidecadal Oscillation, loss of Arctic sea ice, the fluctuating jet stream, and regular incursions of polar air into the northeastern US. PMID:26971874

  14. Arctic Vortex changes alter the sources and isotopic values of precipitation in northeastern US

    NASA Astrophysics Data System (ADS)

    Puntsag, Tamir; Mitchell, Myron J.; Campbell, John L.; Klein, Eric S.; Likens, Gene E.; Welker, Jeffrey M.

    2016-03-01

    Altered atmospheric circulation, reductions in Arctic sea ice, ocean warming, and changes in evaporation and transpiration are driving changes in the global hydrologic cycle. Precipitation isotopic (δ18O and δ2H) measurements can help provide a mechanistic understanding of hydrologic change at global and regional scales. To study the changing water cycle in the northeastern US, we examined the longest (1968–2010) record of precipitation isotope values, collected at the Hubbard Brook Experimental Forest in New Hampshire, US (43o56‧N, 71o45‧W). We found a significant reduction in δ18O and δ2H values over the 43-year record, coupled with a significant increase in d-excess values. This gradual reduction in δ18O and δ2H values unexpectedly occurred during a period of regional warming. We provide evidence that these changes are governed by the interactions among the Atlantic Multidecadal Oscillation, loss of Arctic sea ice, the fluctuating jet stream, and regular incursions of polar air into the northeastern US.

  15. Migration patterns and wintering range of common loons breeding in the Northeastern United States

    USGS Publications Warehouse

    Kenow, K.P.; Adams, D.; Schoch, N.; Evers, D.C.; Hanson, W.; Yates, D.; Savoy, L.; Fox, T.J.; Major, A.; Kratt, R.; Ozard, J.

    2009-01-01

    A study, using satellite telemetry, was conducted to determine the precise migration patterns and wintering locations of Common Loons (Gavia immer) breeding in the northeastern United States. Transmitters were implanted in 17 loons (16 adults and one juvenile) that were captured on breeding lakes in New York, New Hampshire, and Maine during the summers of 2003, 2004, and 2005. Transmitters from ten of the birds provided adequate location data to document movement to wintering areas. Most adult loons appeared to travel non-stop from breeding lakes, or neighboring lakes (within 15 km), to the Atlantic coast. Adult loons marked in New Hampshire and Maine wintered 152 to 239 km from breeding lakes, along the Maine coast. Adult loons marked in the Adirondack Park of New York wintered along the coasts of Massachusetts (414 km from breeding lake), Rhode Island (362 km), and southern New Jersey (527 km). Most of the loons remained relatively stationary throughout the winter, but the size of individual wintering areas of adult loons ranged from 43 to 1,159 km 2, based on a 95% fixed kernel utilization distribution probability. A juvenile bird from New York made a number of stops at lakes and reservoirs en route to Long Island Sound (325 km from breeding lake). Maximum functional life of transmitters was about 12 months, providing an opportunity to document spring migration movements as well. This work provides essential information for development and implementation of regional Common Loon conservation strategies in the Northeastern U.S.

  16. Arctic Vortex changes alter the sources and isotopic values of precipitation in northeastern US

    PubMed Central

    Puntsag, Tamir; Mitchell, Myron J.; Campbell, John L.; Klein, Eric S.; Likens, Gene E.; Welker, Jeffrey M.

    2016-01-01

    Altered atmospheric circulation, reductions in Arctic sea ice, ocean warming, and changes in evaporation and transpiration are driving changes in the global hydrologic cycle. Precipitation isotopic (δ18O and δ2H) measurements can help provide a mechanistic understanding of hydrologic change at global and regional scales. To study the changing water cycle in the northeastern US, we examined the longest (1968–2010) record of precipitation isotope values, collected at the Hubbard Brook Experimental Forest in New Hampshire, US (43o56′N, 71o45′W). We found a significant reduction in δ18O and δ2H values over the 43-year record, coupled with a significant increase in d-excess values. This gradual reduction in δ18O and δ2H values unexpectedly occurred during a period of regional warming. We provide evidence that these changes are governed by the interactions among the Atlantic Multidecadal Oscillation, loss of Arctic sea ice, the fluctuating jet stream, and regular incursions of polar air into the northeastern US. PMID:26971874

  17. Array seismological investigation of the South Atlantic 'Superplume'

    NASA Astrophysics Data System (ADS)

    Hempel, Stefanie; Gassmöller, Rene; Thomas, Christine

    2015-04-01

    We apply the axisymmetric, spherical Earth spectral elements code AxiSEM to model seismic compressional waves which sample complex `superplume' structures in the lower mantle. High-resolution array seismological stacking techniques are evaluated regarding their capability to resolve large-scale high-density low-velocity bodies including interior structure such as inner upwellings, high density lenses, ultra-low velocity zones (ULVZs), neighboring remnant slabs and adjacent small-scale uprisings. Synthetic seismograms are also computed and processed for models of the Earth resulting from geodynamic modelling of the South Atlantic mantle including plate reconstruction. We discuss the interference and suppression of the resulting seismic signals and implications for a seismic data study in terms of visibility of the South Atlantic `superplume' structure. This knowledge is used to process, invert and interpret our data set of seismic sources from the Andes and the South Sandwich Islands detected at seismic arrays spanning from Ethiopia over Cameroon to South Africa mapping the South Atlantic `superplume' structure including its interior structure. In order too present the model of the South Atlantic `superplume' structure that best fits the seismic data set, we iteratively compute synthetic seismograms while adjusting the model according to the dependencies found in the parameter study.

  18. Fracture zones in the equatorial Atlantic and the breakup of western Pangea

    SciTech Connect

    Jones, E.J.W.

    1987-06-01

    The early breakup of western Pangea has been investigated by mapping the pattern of fracture zones and distribution of seismic reflectors within the sedimentary cover of the Atlantic between the Cape Verde Islands and the equator. Two distinct sets of transverse oceanic lineaments are present, separated by the Guinea Fracture Zone near lat 10/sup 0/N. Lineaments to the north are associated with the formation of the central Atlantic in the Late Jurassic and Early Cretaceous; those in the south relate to the Cretaceous opening of the South Atlantic. The Guinea Fracture Zone is thus the conjugate of the Jurassic transform boundary under peninsular Florida, which linked the Atlantic with the Gulf of Mexico. The distribution of dated seismic reflectors suggests that deposition of deep-water sediments was confined to the region north of the Guinea transform until Aptian time, when the Sierra Leone Basin began to open. The latter started to widen at least 15 m.y. after the initiation of the Cape Basin off southwest Africa, an age difference that can be explained if a short-lived plate boundary developed in either Africa or South America during the Early Cretaceous. Neither the trends of the equatorial fracture zones nor the seismic stratigraphy supports the existence of a predrift gap between west Africa and Brazil.

  19. Early Triassic geologic history of northeastern Nevada

    SciTech Connect

    Paull, R.K.; Paull, R.A.

    1986-08-01

    Conodont biostratigraphic and lithostratigraphic studies of Lower Triassic rocks in northeastern Elko County, Nevada, and adjacent parts of Idaho and Utah provide new information about regional geologic history. A sequential summary of Early Triassic events in this area follows: (1) rapid transgression of the Griesbachian sea to limiting barriers on the south (Oquirrh-Uinta axis) and west (Humboldt highland.). (2) Although the initial Triassic transgression may have persisted farther south and west than present-day evidence indicates, a period of progradation during the Dienerian limited marine sedimentation to northeastern-most Nevada and adjacent states. (3) In Smithian time, a widespread transgression spilled south and west over the earliest Triassic basin margin. (4) The southward flood is characterized by locally spectacular basal conglomerates followed by shallow marine deposits of the Thaynes Formation. (5) The transgression to the west was facilitated by tectonic removal of the restrictive barrier during the Smithian. This resulted in a slope-basin environment that accumulated a thick sequence of shale and calcareous siltstone with interbeds of turbidite conglomerates, olistostromes, and exotic blocks derived from Permian formations in northern Nevada or adjacent Idaho. (6) During a regional progradation in early Spathian time, marine conditions persisted in northeastern Nevada. (7) A final depositional episode is documented by the progressive westward spread of carbonate rocks of the Thaynes Formation. (8) Withdrawal of Triassic seas from northeast Nevada occurred post-latest Early Triassic, since a carbonate sequence of more than 300 m overlies the youngest dated interval.

  20. Layered Atlantic Smoke Interactions with Clouds (LASIC) Science Plan

    SciTech Connect

    Zuidema, P; Chiu, C; Fairall, CW; Ghan, SJ; Kollias, P; McFarguhar, GM; Mechem, DB; Romps, DM; Wong, H; Yuter, SE; Alvarado, MJ; DeSzoeke, SP; Feingold, G; Haywood, JM; Lewis, ER; McComiskey, A; Redemann, J; Turner, DD; Wood, R; Zhu, P

    2015-12-01

    Southern Africa is the world’s largest emitter of biomass-burning (BB) aerosols. Their westward transport over the remote southeast Atlantic Ocean colocates some of the largest atmospheric loadings of absorbing aerosol with the least examined of the Earth’s major subtropical stratocumulus decks. Global aerosol model results highlight that the largest positive top-of-atmosphere forcing in the world occurs in the southeast Atlantic, but this region exhibits large differences in magnitude and sign between reputable models, in part because of high variability in the underlying model cloud distributions. Many uncertainties contribute to the highly variable model radiation fields: the aging of shortwave-absorbing aerosol during transport, how much of the aerosol mixes into the cloudy boundary layer, and how the low clouds adjust to smoke-radiation and smoke-cloud interactions. In addition, the ability of the BB aerosol to absorb shortwave radiation is known to vary seasonally as the fuel type on land changes.

  1. Atmospheric Chemistry Over Southern Africa

    NASA Technical Reports Server (NTRS)

    Gatebe, Charles K.; Levy, Robert C.; Thompson, Anne M.

    2011-01-01

    During the southern African dry season, regional haze from mixed industrial pollution, biomass burning aerosol and gases from domestic and grassland fires, and biogenic sources from plants and soils is worsened by a semi-permanent atmosphere gyre over the subcontinent. These factors were a driver of several major international field campaigns in the 1990s and early 2000s, and attracted many scientists to the region. Some researchers were interested in understanding fundamental processes governing chemistry of the atmosphere and interaction with climate change. Others found favorable conditions for evaluating satellite-derived measurements of atmospheric properties and a changing land surface. With that background in mind a workshop on atmospheric chemistry was held in South Africa. Sponsored by the International Commission for Atmospheric Chemistry and Global Pollution (ICACGP; http://www.icacgp.org/), the workshop received generous support from the South African power utility, Eskom, and the Climatology Research Group of the University of the Witwatersrand, Johannesburg, South Africa. The purpose of the workshop was to review some earlier findings as well as more recent findings on southern African climate vulnerability, chemical changes due to urbanization, land-use modification, and how these factors interact. Originally proposed by John Burrows, president of ICACGP, the workshop was the first ICACGP regional workshop to study the interaction of air pollution with global chemical and climate change. Organized locally by the University of the Witwatersrand, the workshop attracted more than 60 delegates from South Africa, Mozambique, Botswana, Zimbabwe, France, Germany, Canada, and the United States. More than 30 presentations were given, exploring both retrospective and prospective aspects of the science. In several talks, attention was focused on southern African chemistry, atmospheric pollution monitoring, and climate processes as they were studied in the field

  2. Carbon disulfide measurements in the atmosphere of the western North Atlantic and the northwestern South Atlantic Oceans

    NASA Technical Reports Server (NTRS)

    Bandy, Alan R.; Thornton, Donald C.; Johnson, James E.

    1993-01-01

    Carbon disulfide (CS2) measurements were made over the western and equatorial North Atlantic Ocean and the northwestern and equatorial South Atlantic Ocean. Carbon disulfide was in the range 0.4-50 pptrv in the atmosphere of the western North Atlantic Ocean. Emissions from anthropogenic sources and wet lands were found to be important although anthropogenic sources were 4-6 times larger than biogenic sources. The flux of CS2 from eastern North America between 30 and 39 deg latitude was estimated to be 2 x 10(exp 8)g/yr or sulfur. The anthropogenic contribution was 1.8 x 10(exp 8)g/yr of sulfur whereas the contribution of marshes was 0.2 x 10(exp 8)g/yr of sulfur. Sources of CS2 at high latitudes in the northern hemisphere were comparatively weak. Carbon disulfide levels in the western South Atlantic Ocean between -5 and 1 deg latitude were in the range 0.2-6 pptrv. Most of the CS2 appeared to come from biomass burning in Africa. Carbon disulfide was much higher close to shore suggesting that the South American continent was a significant source although too few data were available to quantify it. On ferry lights from Wallops, Virginia to Natal, Brazil, CS2 levels at the ferry altitude of about 6 km averaged 1.2 pptrv. This background CS2 was adequate to account for all the carbonyl sulfide (OCS) in the atmosphere.

  3. What controls early or late onset of tropical North Atlantic hurricane season?

    NASA Astrophysics Data System (ADS)

    Zuo, Heng; Li, Tim; Liu, Jia; Peng, Melinda

    2016-06-01

    The occurrence of first hurricane in early summer signifies the onset of an active Atlantic hurricane season. The interannual variation of this hurricane onset date is examined for the period 1979-2013. It is found that the onset date has a marked interannual variation. The standard deviation of the interannual variation of the onset day is 17.5 days, with the climatological mean onset happening on July 23. A diagnosis of tropical cyclone (TC) genesis potential index (GPI) indicates that the major difference between an early and a late onset group lies in the maximum potential intensity (MPI). A further diagnosis of the MPI shows that it is primarily controlled by the local SST anomaly (SSTA). Besides the SSTA, vertical shear and mid-tropospheric relative humidity anomalies also contribute significantly to the GPI difference between the early and late onset groups. It is found that the anomalous warm (cold) SST over the tropical Atlantic, while uncorrelated with the Niño3 index, persists from the preceding winter to concurrent summer in the early (late) onset group. The net surface heat flux anomaly always tends to damp the SSTA, which suggests that ocean dynamics may play a role in maintaining the SSTA in the tropical Atlantic. The SSTA pattern with a maximum center in northeastern tropical Atlantic appears responsible for generating the observed wind and moisture anomalies over the main TC development region. A further study is needed to understand the initiation mechanism of the SSTA in the Atlantic.

  4. Contextual view showing northeastern eucalyptus windbreak and portion of citrus ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Contextual view showing northeastern eucalyptus windbreak and portion of citrus orchard. Camera facing 118" east-southeast. - Goerlitz House, 9893 Highland Avenue, Rancho Cucamonga, San Bernardino County, CA

  5. Language in South Africa.

    ERIC Educational Resources Information Center

    Mesthrie, Rajend, Ed.

    This collection of 24 papers focuses on language and society in South Africa. Part 1, "The Main Language Groupings," includes (1) "South Africa: A Sociolinguistic Overview" (R. Mesthrie); (2) "The Khoesan Languages" (A. Traill); (3) "The Bantu Languages: Sociohistorical Perspectives" (Robert K. Herbert and Richard Bailey); (4) "Afrikaans:…

  6. Generation 2030/Africa

    ERIC Educational Resources Information Center

    You, Danzhen; Hug, Lucia; Anthony, David

    2014-01-01

    Until relatively recently, much of Africa has been among the economically least developed and least densely populated places on earth, replete with villages and rural communities. Africa is changing rapidly, in its economy, trade and investment; in climate change; in conflict and stability; in urbanization, migration patterns, and most of all in…

  7. Magnetotactic bacteria population in a pristine French Atlantic lagoon.

    PubMed

    Pradel, Nathalie; Fuduche, Maxime; Ollivier, Bernard

    2016-01-01

    In this study, we report for the first time the presence of magnetotactic bacteria (MTB) on the Northeastern Atlantic coast. Microscopy observations indicated a heterogeneous population of MTB morphotypes. The analysis of the 16S rDNA by pyrosequencing technology revealed four operational taxonomic sequence units affiliated within the Magnetococcales order, class Alphaproteobacteria. One of them was closely related to sequences of MTB from the Tunisian coast, central Mediterranean Sea. This work offers information on anew environmental context and on biogeography of MTB, highlights the putative impact that marine currents may have on MTB distribution on Earth, and underlines the role that pristine or polluted areas may play on the structure of the MTB communites. PMID:26335530

  8. Aeolian Sediments on the northeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Stauch, G.; Lehmkuhl, F.

    2013-12-01

    The timing and spatial distribution of aeolian sediments on the northeastern Tibetan Plateau have gained increasing interest during the last decades. The formation of the aeolian deposits is often related to cold and dry climate conditions. However, further important parameters are the local geomorphological setting and sediment availability in the source areas of the sediments. Aeolian sediments including loess, sandy loess and sands are widespread in the catchment of the Donggi Cona on the northeastern Tibetan Plateau at around 4000 m asl. Detailed geomorphological mapping of the deposits and geochemical analyses of the sediments revealed varying sources throughout the Holocene. The timing of the sediment deposition is based on 43 OSL (optical stimulated luminescence) ages. Several phases of enhanced aeolian deposition took place during the Holocene. The accumulation of aeolian sands lasted from 10.5 until 7 ka. The main source area of these sands was a large alluvial fan. Parallel to the formation of the dunes loess was deposited on the adjacent slopes from 10.5 until 7.5 ka. These sediments most probably originate in the nearby Qaidam Basin. In contrast to the general linkage of aeolian sediments to dryer climate conditions formation of these aeolian deposits is related to wetter conditions due to a strengthening of the Asian Summer Monsoons. The wetter climate enhanced the trapping and continuous fixation of the aeolian sediments by vegetation. With the further strengthening of the Monsoon fluvial processes eroded the aeolian deposits at least until 6 ka. From about 3 ka to the present a reactivation of aeolian sands and the formation of new dunes took place. This reactivation is related to drier conditions on the north-eastern Tibetan Plateau. Additionally, an increased human influence might have enhanced the aeolian activity. Similar phases of enhanced aeolian activity have been documented in more than 170 available OSL ages from loess and aeolian sands in

  9. An investigation of Ekman upwelling in the North Atlantic

    NASA Technical Reports Server (NTRS)

    Mcclain, Charles R.; Firestone, James

    1993-01-01

    The spatial and temporal variability of the North Atlantic Ekman upwelling fields on seasonal and interannual time scales is investigated on the basis of surface winds from the Fleet Numerical Oceanography Center for 1979-1986. A pronounced minimum in the basin-wide monthly mean vertical Ekman velocities during 1981-1982 is found. It is shown that the primary source of the interannual signal was the region off NW Africa in the vicinity of the Guinea Dome. Other sectors of the basin experienced no significant interannual trends. Hydrographic data and SST data from the NW Africa sector for 1981-1986 indicate a cooling trend beginning in late 1982, consistent with increased upwelling. The fall and winter seasons' mixed layers at the center of the Guinea Dome were deeper in 1984 and 1985 than in previous years. The potential impact of large interannual variations in Ekman upwelling on basin-wide primary productivity is discussed.

  10. Interannual variability of the mixed layer winter convection and spiciness generation in the Eastern Subtropical North Atlantic

    NASA Astrophysics Data System (ADS)

    Kolodziejczyk, Nicolas; Reverdin, Gilles; Lazar, Alban

    2014-05-01

    The Argo data set is used to study the winter conditions in the north-eastern subtropical-tropical Atlantic during 2006-2012. During winter 2010, the mixed layer depth is abnormally shallow and a strong negative anomaly of density compensated salinity ('spiciness') is generated in the permanent pycnocline. This is primary explained by unusual weak buoyancy flux during the late winter in the subtropical north-eastern Atlantic (NEA). These conditions contrast with the 5 other studied winters, that show deeper mixed layer and positive spiciness anomalies in the permanent pycnocline. Particularly deep mixed layer and strong spiciness anomalies are observed during late winter 2012. The conditions during winter 2010 are likely explained by historically low North Atlantic Oscillation (NAO) and high Tropical North Atlantic index (TNA). Interannual variability of the eastern subtropical mixed layer is investigated using a simple 1-D bulk model including a mean thermohaline (temperature and salinity) linear profiles, and turbulent kinetic energy (TKE) conservation in the upper ocean layer, and interannual air-sea buoyancy forcing during the fall-winters 2006-2012. The mixed layer depth and the thermohaline ('spiciness') anomalies generated in a strongly compensated layer at the base of the mixed layer and in the permanent pycnocline are associated with the convective mixing driven by the atmospheric buoyancy flux during the boreal winter season.

  11. Two Distinct Roles of Atlantic SSTs in ENSO Variability: North Tropical Atlantic SST and Atlantic Nino

    NASA Technical Reports Server (NTRS)

    Ham, Yoo-Geun; Kug, Jong-Seong; Park, Jong-Yeon

    2013-01-01

    Two distinct roles of the Atlantic sea surface temperatures (SSTs), namely, the North Tropical Atlantic (NTA) SST and the Atlantic Nino, on the El Nino-Southern Oscillation (ENSO) variability are investigated using the observational data from 1980 to 2010 and coupled model experiments. It appears that the NTA SST and the Atlantic Nino can be used as two independent predictors for predicting the development of ENSO events in the following season. Furthermore, they are likely to be linked to different types of El Nino events. Specifically, the NTA SST cooling during February, March, and April contributes to the central Pacific warming at the subsequent winter season, while the negative Atlantic Nino event during June, July, and August contributes to enhancing the eastern Pacific warming. The coupled model experiments support these results. With the aid of a lagged inverse relationship, the statistical forecast using two Atlantic indices can successfully predict various ENSO indices.

  12. Long-Term Simulation of Dust Distribution with the GOCART Model: Correlation with the North Atlantic Oscillation

    NASA Technical Reports Server (NTRS)

    Ginoux, P.; Prospero, J.; Torres, O.; Chin, M.

    2002-01-01

    Global distribution of aeolian dust is simulated from 1981 to 1996 with the Goddard Ozone Chemistry Aerosol Radiation and Transport (GOCART) model. The results are assessed with in-situ measurements and the Total Ozone Mapping Spectrometer (TOMS) aerosol products. The annual budget over the different continents and oceans are analyzed. It is found that there is a maximum of 25% difference of global annual emission from the minimum in 1996 to the maximum in 1988. There is a downward trend of dust emission over Africa and East Asia, of 6 and 2 Tg/yr, respectively. The inter-annual variability of dust distribution is analyzed over the North Atlantic and Africa. It is found that in winter most of the North Atlantic and Africa dust loading is correlated with the North Atlantic Oscillation. The GOCART model indicates that a controlling factor of such correlation can be attributed to dust emission from the Sahel. The Bodele depression is the major dust source in winter and its inter-annual variability is highly correlated with the NAO. However, it is not possible to conclude without further analysis that the North Atlantic Oscillation is forcing the inter-annual variability of dust emission and in-turn dust concentration over the North Atlantic.

  13. A benthic foraminiferal record of middle to late Pliocene (3.15-2.85 Ma) deep water change in the North Atlantic

    USGS Publications Warehouse

    Ishman, S.E.

    1996-01-01

    Records of benthic foraminifera from North Atlantic DSDP Site 607 and Hole 610A indicate changes in deep water conditions through the middle to late Pliocene (3.15 to 2.85 Ma). Quantitative analyses of modern associations in the North Atlantic indicate that seven species, Fontbotia wuellerstorfi, Cibicidoides kullenbergi, Uvigerina peregrina, Nuttallides umboniferus, Melonis pompilioides, Globocassidulina subglobosa and Epistominella exigua are useful for paleoenvironmental interpretation. The western North Atlantic basin (Site 607) was occupied by North Atlantic Deep Water (NADW) until ???2.88 Ma. At that time, N. umboniferus increased, indicating an influx of Southern Ocean Water (SOW). The eastern North Atlantic basin (Hole 610A) was occupied by a relatively warm water mass, possibly Northeastern Atlantic Deep Water (NEADW), through ???2.94 Ma when SOW more strongly influenced the site. These interpretations are consistent with benthic ??18O and ??13C records from 607 and 610A (Raymo et al., 1992). The results presented in this paper suggest that the North Atlantic was strongly influenced by northern component deep water circulation until 2.90-2.95 Ma. After that there was a transition toward a glacially driven North Atlantic circulation more strongly influenced by SOW associated with the onset of Northern Hemisphere glaciation. The circulation change follows the last significant SST and atmospheric warming prior to ???2.6 Ma.

  14. Structure and Dynamics of the Shark Assemblage off Recife, Northeastern Brazil

    PubMed Central

    Afonso, André S.; Andrade, Humber A.; Hazin, Fábio H. V.

    2014-01-01

    Understanding the ecological factors that regulate elasmobranch abundance in nearshore waters is essential to effectively manage coastal ecosystems and promote conservation. However, little is known about elasmobranch populations in the western South Atlantic Ocean. An 8-year, standardized longline and drumline survey conducted in nearshore waters off Recife, northeastern Brazil, allowed us to describe the shark assemblage and to monitor abundance dynamics using zero-inflated generalized additive models. This region is mostly used by several carcharhinids and one ginglymostomid, but sphyrnids are also present. Blacknose sharks, Carcharhinus acronotus, were mostly mature individuals and declined in abundance throughout the survey, contrasting with nurse sharks, Ginglymostoma cirratum, which proliferated possibly due to this species being prohibited from all harvest since 2004 in this region. Tiger sharks, Galeocerdo cuvier, were mostly juveniles smaller than 200 cm and seem to use nearshore waters off Recife between January and September. No long-term trend in tiger shark abundance was discernible. Spatial distribution was similar in true coastal species (i.e. blacknose and nurse sharks) whereas tiger sharks were most abundant at the middle continental shelf. The sea surface temperature, tidal amplitude, wind direction, water turbidity, and pluviosity were all selected to predict shark abundance off Recife. Interspecific variability in abundance dynamics across spatiotemporal and environmental gradients suggest that the ecological processes regulating shark abundance are generally independent between species, which could add complexity to multi-species fisheries management frameworks. Yet, further research is warranted to ascertain trends at population levels in the South Atlantic Ocean. PMID:25010514

  15. Structure and dynamics of the shark assemblage off Recife, Northeastern Brazil.

    PubMed

    Afonso, André S; Andrade, Humber A; Hazin, Fábio H V

    2014-01-01

    Understanding the ecological factors that regulate elasmobranch abundance in nearshore waters is essential to effectively manage coastal ecosystems and promote conservation. However, little is known about elasmobranch populations in the western South Atlantic Ocean. An 8-year, standardized longline and drumline survey conducted in nearshore waters off Recife, northeastern Brazil, allowed us to describe the shark assemblage and to monitor abundance dynamics using zero-inflated generalized additive models. This region is mostly used by several carcharhinids and one ginglymostomid, but sphyrnids are also present. Blacknose sharks, Carcharhinus acronotus, were mostly mature individuals and declined in abundance throughout the survey, contrasting with nurse sharks, Ginglymostoma cirratum, which proliferated possibly due to this species being prohibited from all harvest since 2004 in this region. Tiger sharks, Galeocerdo cuvier, were mostly juveniles smaller than 200 cm and seem to use nearshore waters off Recife between January and September. No long-term trend in tiger shark abundance was discernible. Spatial distribution was similar in true coastal species (i.e. blacknose and nurse sharks) whereas tiger sharks were most abundant at the middle continental shelf. The sea surface temperature, tidal amplitude, wind direction, water turbidity, and pluviosity were all selected to predict shark abundance off Recife. Interspecific variability in abundance dynamics across spatiotemporal and environmental gradients suggest that the ecological processes regulating shark abundance are generally independent between species, which could add complexity to multi-species fisheries management frameworks. Yet, further research is warranted to ascertain trends at population levels in the South Atlantic Ocean. PMID:25010514

  16. Phylogeography of four frog species in forest fragments of northeastern Brazil--a preliminary study.

    PubMed

    Carnaval, Ana Carolina O Q

    2002-11-01

    I contrast mitochondrial DNA genealogies based on 612 bp of the cytochrome b gene across four co-distributed species of frogs in Northeastern Brazil. They are Hyla albomarginata, Hyla branneri, Proceratophrys boiei, and Scinax nebulosus. Samples were collected from the core or edge of six rainforest remnants in the states of Pernambuco and Alagoas. Three fragments are located within the humid Atlantic Forest morphoclimatic domain (municipalities of Cabo de Santo Agostinho, Ibateguara, and Jaqueira), two are located in the transition zone between the Atlantic Forest domain and the semi-arid Caatinga (Caruaru and Timbaúba), and one is found within the Caatinga (Brejo da Madre de Deus). Results show that local patterns and levels of genetic diversity are influenced by taxon-specific habitat requirements. Populations of the montane, closed-canopy species P. boiei show strong geographical structure, reflecting barriers to gene flow that predate human-driven habitat destruction. Species occurring along forest edges, such as H. albomarginata and S. nebulosus, show genetic patterns similar to those of P. boiei, but lower levels of genetic divergence. The more generalist Hyla branneri shows no geographic pattern. The data are in agreement with distribution and fossil data gathered for other groups of organisms, suggesting that mesic forests occupied the currently arid Caatinga in the recent past. PMID:21680371

  17. Coupling of millennial-scale changes in sea surface temperature and precipitation off northeastern Brazil with high-latitude climate shifts during the last glacial period

    NASA Astrophysics Data System (ADS)

    Jaeschke, Andrea; Rühlemann, Carsten; Arz, Helge; Heil, Gerrit; Lohmann, Gerrit

    2007-12-01

    High-resolution records of alkenone-derived sea surface temperatures and elemental Ti/Ca ratios from a sediment core retrieved off northeastern Brazil (4°S) reveal short-term climate variability throughout the past 63,000 a. Large pulses of terrigenous sediment discharge, caused by increased precipitation in the Brazilian hinterland, coincide with Heinrich events and the Younger Dryas period. Terrigenous input maxima related to Heinrich events H6-H2 are characterized by rapid cooling of surface water ranging between 0.5° and 2°C. This signature is consistent with a climate model experiment where a reduction of the Atlantic meridional overturning circulation (AMOC) and related North Atlantic cooling causes intensification of NE trade winds and a southward movement of the Intertropical Convergence Zone, resulting in enhanced precipitation off northeastern Brazil. During deglaciation the surface temperature evolution at the core site predominantly followed the Antarctic warming trend, including a cooling, prior to the Younger Dryas period. An abrupt temperature rise preceding the onset of the Bølling/Allerød transition agrees with model experiments suggesting a Southern Hemisphere origin for the abrupt resumption of the AMOC during deglaciation caused by Southern Ocean warming and associated with northward flow anomalies of the South Atlantic western boundary current.

  18. Do West African thunderstorms predict the intensity of Atlantic hurricanes?

    NASA Astrophysics Data System (ADS)

    Price, Colin; Reicher, Naama; Yair, Yoav

    2015-04-01

    Since 85% of all major Atlantic hurricanes originate as thunderstorm clusters in equatorial Africa, we have investigated the connection between these African thunderstorms and the consequent development of these disturbances into tropical storms. We have analyzed Meteosat infrared cloud top temperature data to determine the areal coverage of cold cloud tops over a 6 year period from 2005 to 2010. In addition, hurricane statistics from the same period (intensity, date of generation, location, and maximum winds) were obtained from the National Hurricane Center database. We first show that the areal coverage of cold clouds (with brightness temperatures Tb < -50°C) in tropical Africa is a good indicator of the monthly number of African Easterly Waves (AEWs) leaving the west coast of tropical Africa. Furthermore, the AEWs that develop into tropical storms have a significantly larger area covered by cold cloud tops compared with nondeveloping waves. Finally, we show that on a storm-by-storm basis, the cold cloud coverage in West Africa is positively correlated (r = 0.57) with the accumulated cyclone energy of the future tropical cyclones that develop out of these waves.

  19. Do West African Thunderstorms Predict the Intensity of Atlantic Hurricanes?

    NASA Astrophysics Data System (ADS)

    Price, Colin; Reicher, Naama; Yair, Yoav

    2015-04-01

    Since 85% of all major Atlantic hurricanes originate as thunderstorm clusters in equatorial Africa, we have investigated the connection between these African thunderstorms and the consequent development of these disturbances into tropical storms. We have analyzed METEOSAT infrared cloud-top temperature data to determine the areal coverage of cold cloud tops over a six year period from 2005-2010. In addition, hurricane statistics from the same period (intensity, date of generation, location, maximum winds) were obtained from the National Hurricane Center (NHC) data base. We first show that the areal coverage of cold clouds (with brightness temperatures Tb<-50oC) in tropical Africa is a good indicator of the monthly number of African Easterly Waves (AEWs) leaving the west coast of tropical Africa. Furthermore, the AEWs that develop into tropical storms have a significantly larger area covered by cold cloud tops compared with non-developing waves. Finally, we show that on a storm-by-storm basis, the cold cloud coverage in West Africa is positively correlated (r=0.57) with the accumulated cyclone energy (ACE) of the future tropical cyclones that develop out of these waves.

  20. Multiproxy (pollen, stable isotopes, trace elements) reconstruction of climate variability in northeastern Amazon during the late Holocene

    NASA Astrophysics Data System (ADS)

    Conte, M. H.; Urrego, D. H.; Charles-Dominique, P.; Giraudeau, J.; Martinez, P.; Bush, M. B.; Huang, Y.; Russell, J. M.; Gaucher, P.

    2013-12-01

    Model projections of future climate predict changes in ocean-atmosphere processes that will affect the organization of the Atlantic Intertropical Convergence Zone (ITCZ) and ENSO, and in turn, precipitation patterns over much of South America. The northeastern Amazon is particularly sensitive to ITCZ and ENSO organization, and experiences major episodes of drought and rainfall extremes due to interannual variability in ITCZ intensity and position. Hence understanding Holocene climate variability in the northeastern Amazon, and its phasing with other South American records, can provides new insights into past ITCZ organization and Atlantic-Pacific teleconnections. Lac Toponowini is a landslide-dammed lake in the undisturbed highland rainforest of French Guiana (Guyane). Toponowini sediments are finely varved, with pronounced light-dark couplets that appear to reflect alternating wet and dry season conditions. High-resolution X-Ray Fluorescence (XRF) profiling reveals that the couplets consist of bands of weathered clays and organic-rich material containing co-precipitated sulfides and platinum group elements (PGEs), sourced from gold deposits in the watershed. Mobility of PGEs is highly sensitive to hydrology and groundwater chemistry, and subtle variations in PGE flux and composition in Lac Toponowini appears to track past hydrologic conditions. Of note is the inverse correlation between the Pd/Pb ratio in Toponowini sediments and the %Ti record of fluvial input into the Cariaco Basin (Peterson and Haug 2006, Palaeogeog. Palaeoclim. Palaeoecol. 234, 97-113), which suggests antiphasing between rainfall in northern South America and French Guiana, consistent with ITCZ migration forced by multidecadal Atlantic variability. The carbon isotopic composition (δ13C) of terrestrial leaf waxes exhibits a maximum at ~1500 years BP, consistent with pollen evidence (Ledru 2001, Rev. Paleobot. Palynol. 115, 161-176) for ecosystem adaptations indicative of drier conditions in

  1. Impacts of Low-Flow and Stream-Temperature Changes on Endangered Atlantic Salmon - Current Research

    USGS Publications Warehouse

    Dudley, Robert W.; Hodgkins, Glenn A.; Letcher, Benjamin H.

    2008-01-01

    Recent climate studies in New England and the northeastern United States have shown evidence of physical changes over time, including trends toward earlier snowmelt runoff, decreasing river ice, and increasing spring water temperatures. A U.S. Geological Survey (USGS) study funded by the National Global Warming and Wildlife Science Center will be investigating changes in summer low streamflows and stream temperatures and the potential effects of those changes on endangered Atlantic salmon populations. The study also will evaluate management options that would be most likely to mitigate the effects of any changes in streamflow and temperature.

  2. Livestock First Reached Southern Africa in Two Separate Events

    PubMed Central

    Sadr, Karim

    2015-01-01

    After several decades of research on the subject, we now know when the first livestock reached southern Africa but the question of how they got there remains a contentious topic. Debate centres on whether they were brought with a large migration of Khoe-speakers who originated from East Africa; or whether the livestock were traded down-the-line among hunter-gatherer communities; or indeed whether there was a long history of diverse small scale population movements in this part of the world, one or more of which ‘infiltrated’ livestock into southern Africa. A new analysis of the distribution of stone toolkits from a sizeable sample of sub-equatorial African Later Stone Age sites, coupled with existing knowledge of the distribution of the earliest livestock remains and ceramics vessels, has allowed us to isolate two separate infiltration events that brought the first livestock into southern Africa just over 2000 years ago; one infiltration was along the Atlantic seaboard and another entered the middle reaches of the Limpopo River Basin. These findings agree well with the latest results of genetic research which together indicate that multiple, small-scale infiltrations probably were responsible for bringing the first livestock into southern Africa. PMID:26295347

  3. Livestock First Reached Southern Africa in Two Separate Events.

    PubMed

    Sadr, Karim

    2015-01-01

    After several decades of research on the subject, we now know when the first livestock reached southern Africa but the question of how they got there remains a contentious topic. Debate centres on whether they were brought with a large migration of Khoe-speakers who originated from East Africa; or whether the livestock were traded down-the-line among hunter-gatherer communities; or indeed whether there was a long history of diverse small scale population movements in this part of the world, one or more of which 'infiltrated' livestock into southern Africa. A new analysis of the distribution of stone toolkits from a sizeable sample of sub-equatorial African Later Stone Age sites, coupled with existing knowledge of the distribution of the earliest livestock remains and ceramics vessels, has allowed us to isolate two separate infiltration events that brought the first livestock into southern Africa just over 2000 years ago; one infiltration was along the Atlantic seaboard and another entered the middle reaches of the Limpopo River Basin. These findings agree well with the latest results of genetic research which together indicate that multiple, small-scale infiltrations probably were responsible for bringing the first livestock into southern Africa. PMID:26295347

  4. Barriers to Gene Flow in the Marine Environment: Insights from Two Common Intertidal Limpet Species of the Atlantic and Mediterranean

    PubMed Central

    Sá-Pinto, Alexandra; Branco, Madalena S.; Alexandrino, Paulo B.; Fontaine, Michaël C.; Baird, Stuart J. E.

    2012-01-01

    Knowledge of the scale of dispersal and the mechanisms governing gene flow in marine environments remains fragmentary despite being essential for understanding evolution of marine biota and to design management plans. We use the limpets Patella ulyssiponensis and Patella rustica as models for identifying factors affecting gene flow in marine organisms across the North-East Atlantic and the Mediterranean Sea. A set of allozyme loci and a fragment of the mitochondrial gene cytochrome C oxidase subunit I were screened for genetic variation through starch gel electrophoresis and DNA sequencing, respectively. An approach combining clustering algorithms with clinal analyses was used to test for the existence of barriers to gene flow and estimate their geographic location and abruptness. Sharp breaks in the genetic composition of individuals were observed in the transitions between the Atlantic and the Mediterranean and across southern Italian shores. An additional break within the Atlantic cluster separates samples from the Alboran Sea and Atlantic African shores from those of the Iberian Atlantic shores. The geographic congruence of the genetic breaks detected in these two limpet species strongly supports the existence of transpecific barriers to gene flow in the Mediterranean Sea and Northeastern Atlantic. This leads to testable hypotheses regarding factors restricting gene flow across the study area. PMID:23239977

  5. Poverty reduction in Africa

    PubMed Central

    Collier, Paul

    2007-01-01

    Poverty in Africa has been rising for the last quarter-century, while it has been falling in the rest of the developing world. Africa's distinctive problem is that its economies have not been growing. This article attempts to synthesize a range of recent research to account for this failure of the growth process. I argue that the reasons lie not in African peculiarities but rather in geographic features that globally cause problems but that are disproportionately pronounced in Africa. These features interact to create three distinct challenges that are likely to require international interventions beyond the conventional reliance on aid. PMID:17942702

  6. The ophiolite belts of northeastern China

    NASA Astrophysics Data System (ADS)

    Congzhou, Cao

    Four ophiolite belts, i.e. the Wendur Miao-Xar Moron River, the Solon Mt.-Hegen Mt., the Mudangjiang and the Raohe ophiolite belts, are recognized in northeastern China in various tectogenetic environments, with different ages and geological significance. They may be present in the Upper Proterozoic, lower Lower Paleozoic, lower Upper Paleozoic or Triassic, respectively. They are also formed in oceanic basin, mid-oceanic ridge, island-arc and back-arc basin, and either within plate or between two plates respectively.

  7. Recent sedimentation, northeastern Port Valdez, Alaska

    NASA Astrophysics Data System (ADS)

    Palmer, Harold D.

    1981-09-01

    Sediments accumulating on the northeastern shore of Port Valdez, a fjord leading to Prince William Sound in southern Alaska, are derived from both deltaic and alluvial fan processes. The resulting thick wedge of Recent silts, sands, shells and gravels lies atop irregular ridges of local graywacke bedrock and scattered till deposits. Seismic reflection profiling augmented by soil borings indicates that rapid infilling and upbuilding has occurred at this site. Evidence of slumping suggests general instability of steep submarine slopes in an area characterized by strong earthquakes and large tidal ranges.

  8. MAINE ATLANTIC SALMON HABITAT - GENERAL

    EPA Science Inventory

    ASDENN00 describes, at 1:24,000 scale, important Atlantic salmon habitat of the Dennys River in Maine. The coverage was developed from field surveys conducted on the Dennys River in Maine by staff of the Atlantic Salmon Authority and U.S. Fish and Wildlife Service. This survey wa...

  9. 77 FR 16472 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-21

    ... MSB specifications and management measures was published on October 26, 2011 (76 FR 66260), and the... Amendment (Omnibus Amendment; 76 FR 60606, September 29, 2011), which established annual catch limit (ACL... mackerel, the Omnibus Amendment and Amendment 11 to the MSB FMP (76 FR 68642; November 7, 2011)...

  10. 75 FR 36559 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment 21

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-28

    ... Lightship Access Area (NLAA). For FY 2010, this equates to 47 mt; 103,617 lb (April 9, 2010; 75 FR 18356... described in the status review and the proposed rule published on March 16, 2010 (75 FR 12597)), then... was initially established through Joint Framework 16/39 (69 FR 63460; November 2, 2004),...

  11. 76 FR 23940 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment 22

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-29

    ... measures implemented through Framework 21 (75 FR 36559; June 28, 2010), the Council proposed this trip... schedule that was implemented through Framework 16 to the FMP (69 FR 63460; November 2, 2004). The Council... (LAGC) fleets; open area days-at-sea (DAS) and Sea Scallop Access Area (access area) trip...

  12. 76 FR 34947 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Regulatory Amendment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-15

    ... was most recently amended on March 2, 2011 (76 FR 11373), in Amendment 4 to the Herring FMP (Amendment... stock assessment that over-estimates biomass (75 FR 48874, August 12, 2010). While the herring optimum... June 2007 (72 FR 11252, March 31, 2007) to better match the capacity of the fleet to the size of...

  13. 76 FR 54385 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Regulatory Amendment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-01

    ... revising reporting requirements for the herring fishery was published on June 15, 2011 (75 FR 34947), with... daily via vessel monitoring systems (VMS), open access herring vessels to report catch weekly via the... report herring catch daily via VMS; open access herring vessels report catch weekly via IVR; and...

  14. 75 FR 22073 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment 21

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-27

    ... scallop fishery: Total allowable catch (TAC); open area days-at-sea (DAS) and Sea Scallop Access Area... components: Open area DAS; individual access area trips for limited access vessels; IFQ allocations.... Open Area DAS Allocations This action would implement the following vessel-specific DAS allocations...

  15. 76 FR 43773 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment 22

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-21

    ... Federal Register on April 29, 2011 (76 FR 23940), with a 30-day public comment period that ended May 31... Register on June 1, 2011 (76 FR 31491). Although Framework 22 closes NLS, because Framework 22 was not... Multispecies FMP (76 FR 23042; April 25, 2011) set the total YTF ACLs outlined in Table 3 for FYs 2011 and...

  16. 75 FR 11441 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-11

    ... reduce the bycatch of other finfish species. The Amendment 10 analyses indicate that the stock can be.... Response 4: The Council selected a rebuilding F of 0.1 to facilitate rebuilding based on analyses of stock... in the Loligo fishery. The results of the stock analyses, presented in Appendix 2 of the...

  17. 78 FR 33020 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Amendment 5

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-03

    .... SUPPLEMENTARY INFORMATION: Background On May 8, 2008 (73 FR 26082), the Council published a notice of intent... on December 28, 2009, (74 FR 68577) announcing the split between the amendments, and that impacts... Secretary of Commerce, was published in the Federal Register on April 22, 2013 (78 FR 23733). The...

  18. 78 FR 51131 - Fisheries of the Northeastern United States; Atlantic Coastal Fisheries Cooperative Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-20

    ... personal identifying information (e.g., name, address, etc.), confidential business information, or... measures, we recently published a proposed rule (78 FR 35217; June 12, 2013), based on Commission... recommendations for Federal action to address the poor condition of the Southern New England (SNE) lobster...

  19. 75 FR 63721 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-18

    ..., the final rule for Framework 21 published in the Federal Register (75 FR 36559). The purpose of... through the final rule to Amendment 11 to the Scallop FMP (April 14, 2008; 73 FR 20090). These... (April 27, 2010; 75 FR 22073) and final rules to implement Framework 21. Classification Pursuant to 5...

  20. 78 FR 14230 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-05

    ... NMFS published a proposed rule for Framework Adjustment 7 on December 13, 2012 (77 FR 74159). The... Butterfish (MSB) Fishery Management Plan (FMP) (75 FR 11441, March 11, 2010) as a means of reducing fishing... abundance, the Council recommended and NMFS implemented on January 16, 2013, (78 FR 3346) a much...

  1. 76 FR 66260 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-26

    ... Service. For the reasons set out in the preamble, 50 CFR part 648, as amended at 76 FR 60649, September 29... Impact Review (RIR)/Initial Regulatory Flexibility Analysis (IRFA), are available from: Dr. Christopher M... required analyses, for agency review on August 9, 2011, with final submission on September 15, 2011....

  2. 76 FR 47492 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fishery...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-05

    ... the interim rule published March 15, 2011 (76 FR 13887), is extended through March 16, 2012, unless... (76 FR 13887), as authorized by section 305(c) of the Magnuson-Stevens Act, to increase the butterfish... the MSB Fishery Management Plan (FMP) (76 FR 8306; February 14, 2011). There was one anonymous...

  3. 77 FR 26704 - Fisheries of the Northeastern United States; Northeast Multispecies, Monkfish, Atlantic Sea...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-07

    ... Multispecies Fishery Management Plan was published in the Federal Register on March 23, 2012 (77 FR 16942... utilizing the streamlined form and process NMFS has developed to request a DAS credit, and thus prolong...

  4. Surface signature of Mediterranean water eddies in the Northeastern Atlantic: effect of the upper ocean stratification

    NASA Astrophysics Data System (ADS)

    Bashmachnikov, I.; Carton, X.

    2012-11-01

    Meddies, intra-thermocline eddies of Mediterranean water, can often be detected at the sea surface as positive sea-level anomalies. Here we study the surface signature of several meddies tracked with RAFOS floats and AVISO altimetry. While pushing its way through the water column, a meddy raises isopycnals above. As a consequence of potential vorticity conservation, negative relative vorticity is generated in the upper layer. During the initial period of meddy acceleration after meddy formation or after a stagnation stage, a cyclonic signal is also generated at the sea-surface, but mostly the anticyclonic surface signal follows the meddy. Based on geostrophy and potential vorticity balance, we present theoretical estimates of the intensity of the surface signature. It appears to be proportional to the meddy core radius and to the Coriolis parameter, and inversely proportional to the core depth and buoyancy frequency. This indicates that surface signature of a meddy may be strongly reduced by the upper ocean stratification. Using climatic distribution of the stratification intensity, we claim that the southernmost limit for detection in altimetry of small meddies (with radii on the order of 10-15 km) should lie in the subtropics (35-45° N), while large meddies (with radii of 25-30 km) could be detected as far south as the northern tropics (25-35° N). Those results agree with observations.

  5. 76 FR 31491 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Closure of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-01

    ... Register on April 11 and April 29, 2011, respectively (76 FR 19929 and 76 FR 23940), with the comment... FR 44421; August 21, 1997) specify the following three criteria that define what an emergency... anonymous). You may submit attachments to electronic comments in Microsoft Word, Excel, WordPerfect,...

  6. 78 FR 70009 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Adjustments to 2014 Sub...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-22

    ... discarded herring. Amendment 4 to the Herring FMP final rule (76 FR 11373, March 2, 2011) revised the... rule for Framework 2 and the 2013-15 specifications on October 4, 2013 (78 FR 61828). Among other... Policy Act analyses to support this action were completed in Amendment 4 (76 FR 11373, March 2, 2011)...

  7. 77 FR 20728 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment 23

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-06

    ... January 3, 2012 (77 FR 52), with a 15-day public comment period that ended January 18, 2012. Three... exceeded its sub-ACL by 150 percent). The proposed rule for Framework 47 (77 FR 18179) published in the... regulations to clarify the terminology intended by Amendment 15 to the FMP (76 FR 43746, July 21, 2011),...

  8. 77 FR 67305 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-09

    ... sensitive or protected information. NMFS will accept anonymous comments (enter ``N/A'' in the required... specifications (77 FR 16472; March 21, 2012). The total allowable level of foreign fishing (TALFF) for butterfish..., and in light of the Council's Scientific and Statistical Committee's (SSC) recommended butterfish...

  9. 75 FR 28762 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-24

    ... INFORMATION: Background On March 11, 2010 (75 FR 11441), a final rule was published implementing Amendment 10... specifications and management measures for the 2010 fishing year (February 3, 2010, 75 FR 5537), and becomes..., published on March 11, 2010, at 75 FR 11441, is corrected as follows: 1. On page 11450, beginning in...

  10. Reproductive biology of Urotrygon microphthalmum (Batoidea: Urotrygonidae) from north-eastern Brazil, tropical west Atlantic Ocean.

    PubMed

    Santander-Neto, J; Araújo, M L G; Lessa, R P

    2016-07-01

    The reproductive biology of Urotrygon microphthalmum was studied based on specimens caught as by-catch in shrimp (Litopenaeus schmitti, Xiphopenaeus kroyeri, Farfantepenaeus subtilis and Farfantepenaeus brasiliensis) fishing operations between March 2010 and March 2012 on the coast of Pernambuco, Brazil. Females reached a larger total length (LT ) and total body mass (MT ) (298 mm and 148 g) than males (250 mm and 90 g). Length at maturity was estimated to be 188 and 199 mm LT for males and females. Uterine fecundity ranged from one to four embryos (mean ± s.d.: 1·85 ± 0·45). Size at birth was estimated to be 105 mm LT . Gestation lasted between 4 and 5 months. The reproductive cycle of U. microphthalmum is hypothesized to be asynchronous and biannual. PMID:27005477

  11. 77 FR 69426 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-19

    ...), Commerce. ACTION: Proposed rule, request for comments. SUMMARY: NMFS proposes 2013-2015 specifications and..., 2012, to discuss specification related recommendations for the 2013-2015 mackerel fishery, 2013... Mackerel for 2013-2015, and Butterfish for the 2013 Fishing Year Specifications Mackerel Butterfish...

  12. 78 FR 16573 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery and Northeast...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-15

    ... according to Amendment 11 to the Scallop FMP (Amendment 11; 72 FR 20090; April 14, 2008) fleet allocations... as sub-ACLs and sub-ACTs, respectively, throughout this action. Amendment 15 (76 FR 43746; July 21... closures of these areas implemented through MSA emergency actions (77 FR 64915 (October 24, 2012) and 77...

  13. 78 FR 27088 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery and Northeast...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-09

    ... (78 FR 16574), with a 15-day public comment period that ended April 1, 2013. NMFS received eight... the Scallop FMP (Amendment 11; 72 FR 20090; April 14, 2008) fleet allocations, with 94.5 percent...-ACTs, respectively, throughout this action. Amendment 15 (76 FR 43746; July 21, 2011) specified that...

  14. Stratigraphic framework and petroleum potential of Northeastern Baltimore Canyon Trough, Mid-Atlantic Outer Continental Shelf

    SciTech Connect

    Libby-French, J.

    1984-01-01

    Geologic data from 29 wells in the Baltimore Canyon Trough were released to the public as of 1982, and provide sufficient information for establishing Upper Jurassic through Cenozoic rock-stratigraphic units. The oldest rocks penetrated by exploratory wells are of Late Jurassic age and are correlative to the Scotian Shelf Mohawk, Mic Mac, and Abenaki Formations. The Mohawk(.) sandstone and Mic Mac shale equivalents in the Baltimore Canyon Trough represent lower delta plain to predominantly prodelta environments, and the Abenaki-equivalent limestone represents a shelfmargin carbonate buildup. A destructional phase of the delta is represented by the Naskapi equivalents a calcareous shale. Stratigraphic traps may be present in the Baltimore Canyon Trough Upper Jurassic and Lower Cretaceous deltaic sandstones and shelf-margin carbonates. The deltaic units contain channel and distributary-mouth-bar sandstones, which may be potential reservoirs. The Abenaki stratigraphic-reef trend provides another potential target.

  15. 75 FR 65580 - Fisheries of the Northeastern United States; Atlantic Surfclam and Ocean Quahog Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-26

    ... fishing year. This action is taken under the authority of the implementing regulations for this fishery... FURTHER INFORMATION CONTACT: Anna Macan, Fishery Management Specialist, (978) 281-9165; fax (978) 281-9135. SUPPLEMENTARY INFORMATION: Section 648.72(c) of the regulations implementing the Fishery Management Plan...

  16. 77 FR 52 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment 23

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-03

    ... measures to: Minimize impacts on sea turtles through the requirement of a turtle deflector dredge; improve.... According to recent research indicating where sea turtle interactions most often occur, the proposed area... loggerheads, but Kemps ridley turtles and one green sea turtle have also been observed to interact...

  17. 75 FR 63791 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Amendment 4

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-18

    ... prevent overfishing in all FMPs. A notice of intent (NOI) was published in the Federal Register (73 FR... (74 FR 68577). The Council held three public meetings on Amendment 4 during January 2010. Following... Amendment 4 was published on August 12, 2010 (75 FR 48920). The comment period on the NOA ends on October...

  18. 77 FR 64915 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Emergency Rule...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-24

    ... 14, 2012 (77 FR 28311), is extended to May 14, 2013, unless superseded by another action which will... June 13, 2012 (77 FR 28311, May 14, 2012), as authorized by section 305(c) of the Magnuson-Stevens...) (76 FR 43774; July 21, 2011) set measures extending into FY 2013 as though the DMV would be opened....

  19. 76 FR 68642 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... Federal Register on August 1, 2011 (76 FR 45742), with comments accepted through September 15, 2011. The... Secretary on August 12, 2011, and published as a final rule on September 29, 2011 (76 FR 60606). Several... July 1, 2011 (76 FR 38650). The FEIS describes the impacts of the proposed Amendment 11 measures on...

  20. 76 FR 45742 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-01

    ... multiple occasions since 1992, with the most recent control date set as July 5, 2002 (67 FR 44792, later reaffirmed on June 9, 2005, 70 FR 33728). The Council initially notified the public of its intent to consider...) on March 4, 2005 (70 FR 10605). The Council subsequently conducted scoping meetings in March 2005...

  1. 78 FR 42890 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery and Northeast...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-18

    ..., 2013, the final rule for Joint Framework 24/49 published in the Federal Register (78 FR 27088). The... NGOM as a distinct management area through Amendment 11 to the Scallop FMP (73 FR 20090; April 14, 2008... scallop trips on which an observer is carried onboard the vessel, regardless of whether the vessel...

  2. 75 FR 32745 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-09

    ... meeting dates in a separate Federal Register notice published on May 27, 2010 (75 FR 29725). If the... determine the significance of river herring and shad incidental catch in the MSB fisheries; and the effectiveness and impacts of management measures to minimize bycatch and/or incidental catch of river...

  3. 77 FR 7544 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-13

    ... November 7, 2011 (76 FR ] 68642). The final measures in that action included: A tiered limited access... purposes of Executive Order 12866. Correction In the Federal Register of November 7, 2011, in FR Doc. 2011.... ACTION: Final rule; correction. SUMMARY: This action corrects a mistake in the amendatory language in...

  4. Changes in lagoonal marsh morphology at selected northeastern Atlantic coast sites of significance to migratory waterbirds

    USGS Publications Warehouse

    Erwin, R.M.; Sanders, G.M.; Prosser, D.J.

    2004-01-01

    Five lagoonal salt marsh areas, ranging from 220 ha to 3,670 ha, were selected from Cape Cod, Massachusetts to the southern DelMarVa peninsula, Virginia, USA to examine the degree to which Spartina marsh area and microhabitats had changed from the early or mid- 1900s to recent periods. We chose areas based on their importance to migratory bird populations, agency concerns about marsh loss and sea-level rise, and availability of historic imagery. We georeferenced and processed aerial photographs from a variety of sources ranging from 1932 to 1994. Of particular interest were changes in total salt marsh area, tidal creeks, tidal flats, tidal and non-tidal ponds, and open water habitats. Nauset Marsh, within Cape Cod National Seashore, experienced an annual marsh loss of 0.40% (19% from 1947 to 1994) with most loss attributed to sand overwash and conversion to open water. At Forsythe National Wildlife Refuge in southern New Jersey, annual loss was 0.27% (17% from 1932 to 1995), with nearly equal attribution of loss to open water and tidal pond expansion. At Curlew Bay, Virginia, annual loss was 0.20% (9% from 1949 to 1994) and almost entirely due to perimeter erosion to open water. At Gull Marsh, Virginia, a site chosen because of known erosional losses, we recorded the highest annual loss rate, 0.67% per annum, again almost entirely due to erosional, perimeter loss. In contrast, at the southernmost site, Mockhorn Island Wildlife Management Area, Virginia, there was a net gain of 0.09% per annum (4% from 1949 to 1994), with tidal flats becoming increasingly vegetated. Habitat. implications for waterbirds are considerable; salt marsh specialists such as laughing gulls (Larus atricilla), Forster's terns (Sterna forsteri), black rail, (Laterallus jamaicensis), seaside sparrow (Ammodramus maritimus), and saltmarsh sharp-tailed sparrow (Ammodramus caudacutus) are particularly at risk if these trends continue, and all but the laughing gull are species of concern to state and federal managers.

  5. 75 FR 70187 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-17

    ... (75 FR 3092, January 19, 2010). The deadline for submission was March 22, 2010. The project selection... the Loligo fishery, established in 2010 by MSB Amendment 10 (75 FR 11441, March 11, 2010), could.... Section 648.26 as amended at 75 FR 11450, March 11, 2010, effective January 1, 2011, and is...

  6. 77 FR 28311 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Closure of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-14

    ... Word or Excel, WordPerfect, or Adobe PDF file formats only FOR FURTHER INFORMATION CONTACT: Emily... Framework Adjustment 22 to the Scallop FMP (Framework 22) (76 FR 43774, July 21, 2011). Framework 22 set the... guidelines for the use of emergency rules (62 FR 44421; August 21, 1997) specify the following three...

  7. 77 FR 51853 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-27

    ... Adjustment 6 on June 28, 2012 (77 FR 38566). Additional background information and detail on why and how... implemented Omnibus Amendment for Annual Catch Limits and Accountability Measures (October 31, 2011; 76 FR..., 2011; 76 FR 66260) with the Council's original 2012 butterfish ABC recommendation (3,622 mt)...

  8. 76 FR 79610 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Adjustment to 2012 Annual...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-22

    ... for 2010-2012, which were approved by NMFS on August 12, 2010 (75 FR 48874). Although herring is not... to the Herring FMP (Amendment 4) (76 FR 11373, March 2, 2011) revised the specification-setting... requirements to obtain more timely catch reports (76 FR 54385, September 1, 2011). As a result of...

  9. 77 FR 67624 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Adjustment to 2013 Annual...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-13

    ... by NMFS on August 12, 2010 (75 FR 48874). The stock-wide herring ACL (91,200 mt) is divided among... Herring FMP (Amendment 4) (76 FR 11373, March 2, 2011) revised the specification-setting process, bringing... 2012 herring specifications in a final rule, which became effective on February 24, 2012 (77 FR...

  10. 77 FR 10978 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Adjustment to 2012 Annual...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-24

    ..., which were approved by NMFS on August 12, 2010 (75 FR 48874). Although herring is not overfished and is... FMP (Amendment 4) (76 FR 11373, March 2, 2011) revised the specification-setting process, bringing the... September 2011, NMFS revised vessels reporting requirements to obtain more timely catch reports (76 FR...

  11. 78 FR 12625 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Adjustment to 2013 Annual...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-25

    ... specifications for 2010-2012, which were approved by NMFS on August 12, 2010 (75 FR 48874). The Herring FMP... Area 3. Amendment 4 to the Herring FMP (Amendment 4) (76 FR 11373, March 2, 2011) revised the... Amendment 4 (76 FR 11373, March 2, 2011). This final rule has been determined to be not significant...

  12. 77 FR 38566 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-28

    ... Omnibus Amendment to implement annual catch limits and accountability measures (76 FR 60606). Among other... the 2012 fishing year (2012 butterfish specifications; 77 FR 16472; March 21, 2012), the Council found... Management Council's risk policy regarding stocks without an overfishing limit. The current risk policy...

  13. 78 FR 61828 - Fisheries of the Northeastern United States; Atlantic Herring Fishery; Framework Adjustment 2 and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-04

    ... Framework 2 and the 2013-2015 specifications (Framework 2/2013-2015 Specifications) on August 2, 2013 (78 FR... Amendment 15 and Framework Adjustment 22 to the Scallop Fishery Management Plan (76 FR 43746, July 21, 2011, and 76 FR 43774, July 21, 2011, respectively)). These two scallop actions were directly related,...

  14. 76 FR 11373 - Fisheries of the Northeastern United States; Atlantic Herring; Amendment 4

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-02

    ... Herring FMP. With the implementation of Amendment 1 to the Herring FMP (72 FR 11252, March 12, 2007), the... (Amendment 16) designated haddock catch in the herring fishery as a sub-ACL for the Multispecies FMP (75 FR... buffer against such things as uncertainty in stock size estimates, uncertainty in Canadian catch,...

  15. Atlantic circulation keeps turning.

    PubMed

    Gross, Michael

    2012-10-23

    Two major research projects that are running out in November have investigated the Atlantic circulation system that includes the Gulf Stream and come to the conclusion that there is no immediate risk of it shutting down, allaying fears that were raised seven years ago. Yet a better understanding of the interaction between ocean circulation and climate change is still needed, so two new research projects are going to continue this work and extend it to the implications for fisheries and urban environments. Michael Gross reports. PMID:23256201

  16. Mapping tectonic deformation in the crust and upper mantle beneath Europe and the North Atlantic Ocean.

    PubMed

    Zhu, Hejun; Tromp, Jeroen

    2013-08-23

    We constructed a three-dimensional azimuthally anisotropic model of Europe and the North Atlantic Ocean based on adjoint seismic tomography. Several features are well correlated with historical tectonic events in this region, such as extension along the North Atlantic Ridge, trench retreat in the Mediterranean, and counterclockwise rotation of the Anatolian Plate. Beneath northeastern Europe, the direction of the fast anisotropic axis follows trends of ancient rift systems older than 350 million years, suggesting "frozen-in" anisotropy related to the formation of the craton. Local anisotropic strength profiles identify the brittle-ductile transitions in lithospheric strength. In continental regions, these profiles also identify the lower crust, characterized by ductile flow. The observed anisotropic fabric is generally consistent with the current surface strain rate measured by geodetic surveys. PMID:23929947

  17. Women in Africa

    ERIC Educational Resources Information Center

    Spitzer, Manon

    1975-01-01

    The role and status of women in Africa has changed profoundly since the end of the colonial period. Many differences in women's status and role are based on geography, history, nationality, political and socioeconomic systems, culture, and religion. (JR)

  18. The impact of ENSO on the South Atlantic Subtropical Dipole Mode

    NASA Astrophysics Data System (ADS)

    Rodrigues, Regina; Campos, Edmo; Haarsma, Reindert

    2015-04-01

    The impact of the El Niño - Southern Oscillation (ENSO) on the South Atlantic subtropical dipole mode (SASD) is investigated using both observations and model simulations. The SASD is the dominant mode of coupled ocean-atmosphere variability in the South Atlantic. This study focuses on austral summer, when both ENSO and SASD peak. We show that negative SASD events are associated with central Pacific El Niño events by triggering the Pacific-South America wave train (PSA). The latter resembles the 3rd leading mode of atmospheric variability in the Southern Hemisphere (PSA2) and causes a weakening and meridional shift of the South Atlantic subtropical high, which then generates the negative SASD events. On the other hand, a strengthening of the South Atlantic subtropical high related to central La Niña teleconnections causes positive SASD events. Our results show that the PSA2, triggered by central Pacific ENSO events, connects the tropical Pacific to the Atlantic. This connection is absent from eastern Pacific ENSO events, which appear to initiate the 2nd leading mode of atmospheric variability in the Southern Hemisphere (PSA1). It is for this reason that previous studies have found weak correlations between ENSO and SASD. These findings can improve the climate prediction of southeast South America and southern Africa since these regions are affected by sea surface temperature anomalies of both Pacific and Atlantic oceans.

  19. Advancing decadal-scale climate prediction in the North Atlantic sector.

    PubMed

    Keenlyside, N S; Latif, M; Jungclaus, J; Kornblueh, L; Roeckner, E

    2008-05-01

    The climate of the North Atlantic region exhibits fluctuations on decadal timescales that have large societal consequences. Prominent examples include hurricane activity in the Atlantic, and surface-temperature and rainfall variations over North America, Europe and northern Africa. Although these multidecadal variations are potentially predictable if the current state of the ocean is known, the lack of subsurface ocean observations that constrain this state has been a limiting factor for realizing the full skill potential of such predictions. Here we apply a simple approach-that uses only sea surface temperature (SST) observations-to partly overcome this difficulty and perform retrospective decadal predictions with a climate model. Skill is improved significantly relative to predictions made with incomplete knowledge of the ocean state, particularly in the North Atlantic and tropical Pacific oceans. Thus these results point towards the possibility of routine decadal climate predictions. Using this method, and by considering both internal natural climate variations and projected future anthropogenic forcing, we make the following forecast: over the next decade, the current Atlantic meridional overturning circulation will weaken to its long-term mean; moreover, North Atlantic SST and European and North American surface temperatures will cool slightly, whereas tropical Pacific SST will remain almost unchanged. Our results suggest that global surface temperature may not increase over the next decade, as natural climate variations in the North Atlantic and tropical Pacific temporarily offset the projected anthropogenic warming. PMID:18451859

  20. Atlantic surfclam connectivity within the Middle Atlantic Bight: Mechanisms underlying variation in larval transport and settlement

    NASA Astrophysics Data System (ADS)

    Zhang, Xinzhong; Munroe, Daphne; Haidvogel, Dale; Powell, Eric N.

    2016-05-01

    Larval transport and settlement have been shown in various studies to be essential in determining population abundance and connectivity for benthic invertebrates. This transport is influenced by both the physical environment and biological behavior. The Atlantic surfclam, Spisula solidissima, is a commercially important benthic invertebrate fishery species along the U.S northeastern coast. In this study, a physical circulation model is coupled to a surfclam larval model to investigate the dynamics of larval transport and settlement within the Middle Atlantic Bight (MAB) shelf in 2006. The main physical mechanisms causing variability in larval transport and settlement are also examined. Model results show that surfclam larvae released from July to early October experience relatively larger settlement rates, due to higher average temperatures experienced by larvae. Larval along-shore transport exhibits a mean down-coast pattern following the coastal current from the northeast to the southwest, with most high-frequency (period of 2-10 days) variations caused by fluctuations in the along-shore surface wind stress, and with seasonal variations speculated to be driven mainly by changes in the across-shelf density gradient. Larval across-shelf movement is highly correlated with the along-shore surface wind stress mediated by coastal upwelling and downwelling episodes, but the correlation is further dependent on the vertical distribution of the larvae, particularly their position relative to the thermocline. Most surfclam larvae released from the Middle Atlantic shelf stay below the thermocline and experience a net onshore transport during the summer-stratified season when upwelling-favorable wind forcing dominates. A proposed critical value of water temperature at the thermocline successfully regulates the observed patterns of vertical distribution of surfclam larvae and their across-shelf movement off the New Jersey and South Virginia shelves; that is, when the water

  1. 76 FR 18504 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Quotas and Atlantic Tuna Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-04

    .... See SUPPLEMENTARY INFORMATION for further details. ADDRESSES: As published on March 14, 2011 (76 FR... Species; Atlantic Bluefin Tuna Quotas and Atlantic Tuna Fisheries Management Measures AGENCY: National... bluefin tuna (BFT) base quotas for all domestic fishing categories; establish BFT quota specifications...

  2. Profile of South Africa

    SciTech Connect

    Fox, G.J.; Tonneson, L.C.

    1996-08-01

    A broad overview of the Republic of South Africa`s nuclear energy program is presented. Economic aspects are the main focus of the article, and numerical data is provided for electricity generation and use and uranium production. The role of the molecular laser isotope process for enrichment is discussed. The research reactor program, waste disposal and decommissioning, mining history, uranium production, and nonproliferation policy are other highlighted topics.

  3. Astronomy Landscape in Africa

    NASA Astrophysics Data System (ADS)

    Nemaungani, Takalani

    2015-01-01

    The vision for astronomy in Africa is embedded in the African Space Policy of the African Union in early 2014. The vision is about positioning Africa as an emerging hub for astronomy sciences and facilities. Africa recognized the need to take advantage of its natural resource, the geographical advantage of the clear southern skies and pristine sites for astronomy. The Pan African University (PAU) initiative also presents an opportunity as a post-graduate training and research network of university nodes in five regions of Africa and supported by the African Union. The Southern African node based in South Africa concentrates on space sciences which also includes astronomy. The PAU aims to provide the opportunity for advanced graduate training and postgraduate research to high-performing African students. Objectives also include promoting mobility of students and teachers and harmonizing programs and degrees.A number of astronomy initiatives have burgeoned in the Southern African region and these include the Southern Africa Largest Optical Telescope (SALT), HESS (High Energy Stereoscopic System), the SKA (Square Kilometre Array) and the AVN (African Very Long Baseline Interferometer Network). There is a growing appetite for astronomy sciences in Africa. In East Africa, the astronomy community is well organized and is growing - the East African Astronomical society (EAAS) held its successful fourth annual conference since 2010 on 30 June to 04 July 2014 at the University of Rwanda. Centred around the 'Role of Astronomy in Socio-Economic Transformation,' this conference aimed at strengthening capacity building in Astronomy, Astrophysics and Space Science in general, while providing a forum for astronomers from the region to train young and upcoming scientists.

  4. North Atlantic Bloom

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Reminiscent of the distinctive swirls in a Van Gogh painting, millions of microscopic plants color the waters of the North Atlantic with strokes of blue, turquoise, green, and brown. Fed by nutrients that have built up during the winter and the long, sunlit days of late spring and early summer, the cool waters of the North Atlantic come alive every year with a vivid display of color. The microscopic plants, called phytoplankton, that give the water this color are the base of the marine food chain. Some species of phytoplankton are coated with scales of calcium (chalk), which turn the water electric blue. Chlorophyll and other light-capturing pigments in others give the water a deep green hue. The proliferation of many different species in various stages of growth and decay provides many nuances of color in this concentrated bloom. The bloom stretches across hundreds of kilometers, well beyond the edges of this photo-like image, captured on June 23, 2007, by the Moderate Resolution Imaging Spectroradiometer (MODIS) flying aboard NASA's Aqua satellite. The upper left edge of the image is bounded by Greenland. Iceland is in the upper right. Plumes of dust are blowing off the island, probably adding nutrients to the surface waters to its south. NASA image courtesy Norman Kuring, Ocean Color Group at NASA Goddard Space Flight Center

  5. Mitochondrial DNA affinities at the Atlantic fringe of Europe.

    PubMed

    González, Ana M; Brehm, Antonio; Pérez, José A; Maca-Meyer, Nicole; Flores, Carlos; Cabrera, Vicente M

    2003-04-01

    Mitochondrial DNA analysis of Atlantic European samples has detected significant latitudinal clines for several clusters with Paleolithic (H) and Neolithic (J, U4, U5a1, and U5a1a) coalescence ages in Europe. These gradients may be explained as the result of Neolithic influence on a rather homogeneous Paleolithic background. There is also evidence that some Neolithic clusters reached this border by a continental route (J, J1, J1a, U5a1, and U5a1a), whereas others (J2) did so through the Mediterranean coast. An important gene flow from Africa was detected in the Atlantic Iberia. Specific sub-Saharan lineages appeared mainly restricted to southern Portugal, and could be attributed to historic Black slave trade in the area and to a probable Saharan Neolithic influence. In fact, U6 haplotypes of specific North African origin have only been detected in the Iberian peninsula northwards from central Portugal. Based on this peculiar distribution and the high diversity pi value (0.014 +/- 0.001) in this area compared to North Africa (0.006 +/- 0.001), we reject the proposal that only historic events such as the Moslem occupation are the main cause of this gene flow, and instead propose a pre-Neolithic origin for it. PMID:12627534

  6. Usutu virus in Africa.

    PubMed

    Nikolay, Birgit; Diallo, Mawlouth; Boye, Cheikh Saad Bouh; Sall, Amadou Alpha

    2011-11-01

    Usutu virus (USUV) was discovered in South Africa in 1959. Since then, it has been reported in several African countries including Senegal, Central African Republic, Nigeria, Uganda, Burkina Faso, Cote d'Ivoire, and Morocco. In 2001, USUV has been identified for the first time outside of Africa, namely in Europe, where it caused a significant mortality among blackbirds in Vienna, Austria. In 2009, the first two human cases of USUV infection in Europe have been reported in Italy, causing encephalitis in immunocompromised patients. The host range in Africa includes mainly Culex mosquitoes, birds, and also humans with one benign and one severe case. Given its role as a potential human pathogen and the similar appearance compared with other emerging arboviruses, it is essential to investigate the natural history and ecology of USUV in Africa. In this regard, we review the emergence of USUV in Africa, summarizing data about isolations, host range, and potential vectors, which should help to improve our understanding of the factors underlying the circulation of USUV in Europe and Africa. PMID:21767160

  7. The long-range transport of southern African aerosols to the tropical South Atlantic

    NASA Astrophysics Data System (ADS)

    Swap, R.; Garstang, M.; Macko, S. A.; Tyson, P. D.; Maenhaut, W.; Artaxo, P.; KâLlberg, P.; Talbot, R.

    1996-10-01

    Two episodes of long-range aerosol transport (4000 km) from southern Africa into the central tropical South Atlantic are documented. Stable nitrogen isotope analysis, multielemental analysis, and meteorological observations on local and regional scales are used to describe the observed surface aerosol chemistry during these transport episodes. The chemical, kinematic, and thermodynamic analyses suggest that for the central tropical South Atlantic, west Africa between 0° and 10°S is the primary air mass source region (over 50%) during austral spring. Over 70% of all air arriving in the lower and middle troposphere in the central tropical South Atlantic comes from a broad latitudinal band extending from 20°S to 10°N. Air coming from the east subsides and is trapped below the midlevel and trade wind inversion layers. Air from the west originates at higher levels (500 hPa) and contributes less than 30% of the air masses arriving in the central tropical South Atlantic. The source types of aerosols and precursor trace gases extend over a broad range of biomes from desert and savanna to the rain forest. During austral spring, over this broad region, processes include production from vegetation, soils, and biomass burning. The aerosol composition of air masses over and the atmospheric chemistry of the central South Atlantic is a function of the supply of biogenic, biomass burning, and aeolian emissions from tropical Africa. Rainfall is a common controlling factor for all three sources. Rain, in turn, is governed by the large-scale circulations which show pronounced interannual variability. The field measurements were taken in an extremely dry year and reflect the circulation and transport fields typical of these conditions.

  8. Neotectonism along the Atlantic passive continental margin: A review

    NASA Astrophysics Data System (ADS)

    Gardner, Thomas W.

    1989-09-01

    An extensive body of geologic data including the modern state of stress, historical seismicity, surface and subsurface stratigraphy, numerical models of crustal deformation, surficial geomorphic systems, and historical precise leveling and tidal gauge records constrain the style and rate of neotectonic deformation for the Appalachians and Atlantic passive continental margin. There are two major styles of neotectonism in the eastern United States. The northeastern United States is dominated by isostatic uplift and northward migration of peripheral bulge collapse in response to deglaciation. This locally rapid, but decreasing rate of deformation is superimposed upon slower, long-term deformation along the Atlantic margin. Most of the long-term, continental margin deformation is attributed to lithospheric flexuring in response to sediment loading in sedimentary basins (especially the Baltimore Canyon Trough and Carolina Trough), isostatic deformation in response to continental denudation and water loading of the shelf, and stress from far-field plate tectonic sources. Significant deformational features include an uplift anomaly near Cape Fear, N.C.; northward and southward tilting of the Coastal Plain into the Salisbury and Southeast Georgia Embayments respectively; seaward tilting of the Coastal Plain/Piedmont, and a complex pattern of postglacial uplift and later subsidence in the northeast. Estimates of vertical crustal velocities for similar locations vary over several orders of magnitude. Measurement interval bias and systematic leveling errors may account for some of the discrepancies. Evidence for periodic deformation in the eastern United States in substantial and it is possible that historic data indicate a period of accelerated deformation along the Atlantic continental margin.

  9. Aerosol interactions with African/Atlantic climate dynamics

    NASA Astrophysics Data System (ADS)

    Hosseinpour, F.; Wilcox, E. M.

    2014-07-01

    Mechanistic relationships exist between variability of dust in the oceanic Saharan air layer (OSAL) and transient changes in the dynamics of Western Africa and the tropical Atlantic Ocean. This study provides evidence of possible interactions between dust in the OSAL region and African easterly jet-African easterly wave (AEJ-AEW) system in the climatology of boreal summer, when easterly wave activity peaks. Synoptic-scale changes in instability and precipitation in the African/Atlantic intertropical convergence zone are correlated with enhanced aerosol optical depth (AOD) in the OSAL region in response to anomalous 3D overturning circulations and upstream/downstream thermal anomalies at above and below the mean-AEJ level. Upstream and downstream anomalies are referred to the daily thermal/dynamical changes over the West African monsoon region and the Eastern Atlantic Ocean, respectively. Our hypothesis is that AOD in the OSAL is positively correlated with the downstream AEWs and negatively correlated with the upstream waves from climatological perspective. The similarity between the 3D pattern of thermal/dynamical anomalies correlated with dust outbreaks and those of AEWs provides a mechanism for dust radiative heating in the atmosphere to reinforce AEW activity. We proposed that the interactions of OSAL dust with regional climate mainly occur through coupling of dust with the AEWs.

  10. Convective Lofting Links Indian Ocean Air Pollution to Paradoxical South Atlantic Ozone Maxima

    NASA Technical Reports Server (NTRS)

    Chatfield, Robert B.; Guan, Hong; Thompson, Anne M.; Witte, Jacquelyn C.

    2003-01-01

    We describe a broad resolution of the "Atlantic Paradox" concerning the seasonal and geographic distribution of tropical tropospheric ozone. We describe periods of significant maximum tropospheric O3 for Jan.-April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO)O3 maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, and finally high-level transport to the west, with possible mixing over Africa. For the Jan.- March highest column-O3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 30 or 60 days, more diffuse buildups of Indian-to-Atlantic pollution make important contributions.

  11. Convective lofting links Indian Ocean air pollution to paradoxical South Atlantic ozone maxima

    NASA Technical Reports Server (NTRS)

    Chatfield, R. B.; Guan, H.; Thompson, A. M.; Witte, J. C.

    2005-01-01

    We describe a broad resolution of the Atlantic Parado concerning the seasonal and geographic distribution, of tropical tropospheric ozone. We highlight periods of significant maximum tropospheric O3 for Jan.- April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO) maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, possible stratospheric input, and finally high-level transport to the west, with possible mixing over Africa. For the Jan.-March highest column-O3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 20-50 days, more diffuse buildups of Indian-to-Atlantic pollution make important contributions.

  12. Hematologically and genetically distinct forms of sickle cell anemia in Africa. The Senegal type and the Benin type.

    PubMed

    Nagel, R L; Fabry, M E; Pagnier, J; Zohoun, I; Wajcman, H; Baudin, V; Labie, D

    1985-04-01

    Patients with sickle cell anemia vary in the hematologic and clinical features of their disease, in part because of variability in the presence of linked and unlinked genes that modify the expression of the disease. The hemoglobin S gene is strongly linked to three different haplotypes of polymorphic endonuclease-restriction sites of the beta-like gene cluster (genes in the vicinity of the beta-globin gene)--one prevalent in Atlantic West Africa, another in central West Africa, and yet another in Bantu-speaking Africa (equatorial, East, and southern Africa). We have studied the differences in the hematologic characteristics of patients with sickle cell anemia from the first two geographical areas. We find that the Senegalese (Atlantic West Africa) patients have higher levels of hemoglobin F, a preponderance of G gamma chains in hemoglobin F, a lower proportion of very dense red cells, and a lower percentage of irreversibly sickled cells than those from Benin (central West Africa). We interpret these data to mean that the gamma-chain composition and the hemoglobin F level are haplotype linked and that the decrease in the percentage of dense cells and irreversibly sickled cells is secondary to the elevation in the hemoglobin F level. Patients with sickle cell anemia in the New World probably correspond to various combinations of these types, in addition to the still hematologically undefined haplotype associated with sickle cell anemia in the Bantu-speaking areas of Africa. PMID:2579336

  13. A top to bottom lithospheric study of Africa and Arabia

    NASA Astrophysics Data System (ADS)

    Pasyanos, Michael E.; Nyblade, Andrew A.

    2007-11-01

    We study the lithospheric structure of Africa, Arabia and adjacent oceanic regions with fundamental-mode surface waves over a broad period range. Including group velocities with periods shorter than 35 s allows us to examine shallower features than previous studies of the whole continent. In the process, we have developed a crustal thickness map of Africa. Main features include crustal thickness increases under the West African, Congo, and Kalahari cratons. We find crustal thinning under Mesozoic and Cenozoic rifts, including the Benue Trough, Red Sea, and East, Central, and West African rift systems, along with less abrupt crustal thickness changes at passive continental margins. We also find crustal thickness differences in North Africa between the West African Craton and East Saharan Shield. Crustal shear wave velocities are generally faster in oceanic regions and cratons, and slower in more recent crust and in active and remnant orogenic regions. Deeper structure, related to the thickness of cratons and modern rifting, is generally consistent with previous work. Under cratons we find thick lithosphere and fast upper mantle velocities, while under rifts we find thinned lithosphere and slower upper mantle velocities. However, we also find the lack of a thick cratonic keel beneath the central portion of the Congo Craton. There are no consistent effects in areas classified as hotspots, indicating that there seem to be numerous origins for these features. Finally, it appears that the African Superswell, which is responsible for high elevation and uplift over large portions of Africa, has had a significantly different impact (as indicated by features such as temperature, time of influence, etc.) in the north and the south. This is consistent with episodic activity at shallow depths, which is well-expressed in northeastern Africa and Arabia today.

  14. Enhanced Mediterranean-Atlantic exchange during Atlantic freshening phases

    NASA Astrophysics Data System (ADS)

    Rogerson, M.; Colmenero-Hidalgo, E.; Levine, R. C.; Rohling, E. J.; Voelker, A. H. L.; Bigg, G. R.; SchöNfeld, J.; Cacho, I.; Sierro, F. J.; LöWemark, L.; Reguera, M. I.; de Abreu, L.; Garrick, K.

    2010-08-01

    The Atlantic-Mediterranean exchange of water at Gibraltar represents a significant heat and freshwater sink for the North Atlantic and is a major control on the heat, salt and freshwater budgets of the Mediterranean Sea. Consequently, an understanding of the response of the exchange system to external changes is vital to a full comprehension of the hydrographic responses in both ocean basins. Here, we use a synthesis of empirical (oxygen isotope, planktonic foraminiferal assemblage) and modeling (analytical and general circulation) approaches to investigate the response of the Gibraltar Exchange system to Atlantic freshening during Heinrich Stadials (HSs). HSs display relatively flat W-E surface hydrographic gradients more comparable to the Late Holocene than the Last Glacial Maximum. This is significant, as it implies a similar state of surface circulation during these periods and a different state during the Last Glacial Maximum. During HS1, the gradient may have collapsed altogether, implying very strong water column stratification and a single thermal and δ18Owater condition in surface water extending from southern Portugal to the eastern Alboran Sea. Together, these observations imply that inflow of Atlantic water into the Mediterranean was significantly increased during HS periods compared to background glacial conditions. Modeling efforts confirm that this is a predictable consequence of freshening North Atlantic surface water with iceberg meltwater and indicate that the enhanced exchange condition would last until the cessation of anomalous freshwater supply into to the northern North Atlantic. The close coupling of dynamics at Gibraltar Exchange with the Atlantic freshwater system provides an explanation for observations of increased Mediterranean Outflow activity during HS periods and also during the last deglaciation. This coupling is also significant to global ocean dynamics, as it causes density enhancement of the Atlantic water column via the

  15. ITCZ controls on Late Cretaceous black shale sedimentation in the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Hofmann, P.; Wagner, T.

    2011-12-01

    This study presents high resolution organic and inorganic proxy records for Coniacian to Santonian black shale on the Demerara Rise (ODP Site 1261) in the western tropical Atlantic off South America. We integrate these records with approximately time equivalent geochemical data from the eastern tropical Atlantic off tropical Africa (ODP Site 959) to extract the underlying relationships of Intertropical Convergence Zone (ITCZ) dynamics and black shale formation in the tropical Cretaceous Atlantic at orbital time scales. The geochemical records from the Demerara Rise show repetitive fluctuations in productivity, ocean redox conditions, and clastic sediment supply consistent with a dynamic paleo-upwelling regime off tropical South America. Upwelling intensity most likely was driven by shifts of the mean annual position of the ITCZ, which connects the large-scale precipitation and wind field patterns of the Hadley cells. Upwelling was strongest off South America and burial of oil-prone organic matter most pronounced when the ITCZ was in its southernmost position, which maximized the impact of NE trade winds on the inner, tropical part of the northern Hadley cell. Geochemical records from the Deep Ivorian Basin (equatorial Atlantic) suggest that source rock formation occurred in phase with regions north of the equator. Off tropical Africa, however, black shale formation was primarily driven by regional rainfall and nutrient export. The results of this study provide a conceptual framework that explains the formation, distribution and quality of petroleum source rocks below the tropical component of the Hadley cells on orbital time scales.

  16. Contributions of Tropical Cyclones to the North Atlantic Climatological Rainfall as Observed from Satellites

    NASA Technical Reports Server (NTRS)

    Rodgers, Edward B.; Adler, Robert F.; Pierce, Harold F.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The tropical cyclone rainfall climatology study that was performed for the North Pacific was extended to the North Atlantic. Similar to the North Pacific tropical cyclone study, mean monthly rainfall within 444 km of the center of the North Atlantic tropical cyclones (i.e., that reached storm stage and greater) was estimated from passive microwave satellite observations during, an eleven year period. These satellite-observed rainfall estimates were used to assess the impact of tropical cyclone rainfall in altering the geographical, seasonal, and inter-annual distribution of the North Atlantic total rainfall during, June-November when tropical cyclones were most abundant. The main results from this study indicate: 1) that tropical cyclones contribute, respectively, 4%, 3%, and 4% to the western, eastern, and entire North Atlantic; 2) similar to that observed in the North Pacific, the maximum in North Atlantic tropical cyclone rainfall is approximately 5 - 10 deg poleward (depending on longitude) of the maximum non-tropical cyclone rainfall; 3) tropical cyclones contribute regionally a maximum of 30% of the total rainfall 'northeast of Puerto Rico, within a region near 15 deg N 55 deg W, and off the west coast of Africa; 4) there is no lag between the months with maximum tropical cyclone rainfall and non-tropical cyclone rainfall in the western North Atlantic, while in the eastern North Atlantic, maximum tropical cyclone rainfall precedes maximum non-tropical cyclone rainfall; 5) like the North Pacific, North Atlantic tropical cyclones Of hurricane intensity generate the greatest amount of rainfall in the higher latitudes; and 6) warm ENSO events inhibit tropical cyclone rainfall.

  17. Simulation of Rainfall Variability Over West Africa

    NASA Astrophysics Data System (ADS)

    Bader, J.; Latif, M.

    The impact of sea surface temperature (SST) and vegetation on precipitation over West Africa is investigated with the atmospheric general circulation model ECHAM4.x/T42. Ensemble experiments -driven with observed SST- show that At- lantic SST has a significant influence on JJA precipitation over West Africa. Four- teen experiments were performed in which the climatological SST was enhanced or decreased by one Kelvin in certain ocean areas. Changing SST in the eastern tropi- cal Atlantic only caused significant changes along the Guinea Coast, with a positive SSTA increasing rainfall and a negative reducing it. The response was nearly linear. Changing SST in other ocean areas caused significant changes over West Africa, es- pecially in the Sahel area. The response is found to be non linear, with only negative SSTA leading to significant reduction in Sahel rainfall. Also, the impact of the SSTAs from the different ocean regions was not additive with respect to the rainfall. Four simulations with a coupled model (the simple dynamic vegetation model (SVege) and the ECHAM4-AGCM were coupled) were also performed, driven with observed SST from 1945 to 1998. The standard ECHAM-AGCM -forced by the same observed SST- was able to reproduce the drying trend from the fifties to the mid-eighties in the Sahel, but failed to mirror the magnitude of the rainfall anomalies. The coupled model was not only able to reproduce this drying trend, but was also able to better reproduce the amplitudes of the rainfall anomalies. The dynamic vegetation acted like an amplifier, increasing the SST induced rainfall anomalies.

  18. Urbanization and water supplies for northeastern Colorado

    SciTech Connect

    Smith, R.R.

    1981-03-01

    Increasing populations in northeastern Colorado have resulted in reductions in irrigated acreage and the proportionate quantities of water available to support that segment of the agricultural industry. The growth has caused increased demands for municipal-domestic and industrial water supplies from the South Platte and Colorado River Basins. These impacts have been determined by comparing hydrologic data in conjunction with water use for agricultural, municipal-domestic, and industrial purposes between the period 1975 to 1979. Pricing and water rights ownership were also compared for the same period, as were land conversion data, population data, and crop production valuation. Proper administration of nonconsumptive return flows coupled with the importation of water from the Colorado River Basin will provide adequate, industrial, and irrigation water supplies for this growth intense area and downstream farm lands. 8 figures.

  19. Hantaviruses in Africa.

    PubMed

    Witkowski, Peter T; Klempa, Boris; Ithete, Ndapewa L; Auste, Brita; Mfune, John K E; Hoveka, Julia; Matthee, Sonja; Preiser, Wolfgang; Kruger, Detlev H

    2014-07-17

    This paper summarizes the progress in the search for hantaviruses and hantavirus infections in Africa. After having collected molecular evidence of an indigenous African hantavirus in 2006, an intensive investigation for new hantaviruses has been started in small mammals. Various novel hantaviruses have been molecularly identified not only in rodents but also in shrews and bats. In addition, the first African hantavirus, Sangassou virus, has been isolated and functionally characterized in cell culture. Less is known about the ability of these hantaviruses to infect humans and to cause diseases. To date, no hantavirus genetic material could be amplified from patients' specimens collected in Africa. Serological studies in West Africa, based on a battery of screening and confirmatory assays, led to the detection of hantavirus antibodies in the human population and in patients with putative hantavirus disease. In addition to this overview, we present original data from seroepidemiological and field studies conducted in the Southern part of Africa. A human seroprevalence rate of 1.0% (n=1442) was detected in the South African Cape Region whereas no molecular evidence for the presence of hantavirus was found in 2500 small animals trapped in South Africa and Namibia. PMID:24406800

  20. Neogene desertification of Africa

    NASA Astrophysics Data System (ADS)

    Senut, Brigitte; Pickford, Martin; Ségalen, Loïc

    2009-08-01

    Throughout the Neogene, the faunas and floras in Africa recorded global climatic changes. We present an overview of Neogene desertification in Africa by tracing stable isotopes in eggshells and mammalian enamel, by faunal (changes in hypsodonty, etc.) and floral changes in sequences at the latitudinal extremities of the continent and the equator. This work reveals that desertification started in the southwest ca 17-16 Ma, much earlier than the region of the present-day Sahara (ca 8-7 Ma) and long before the deserts in East Africa (Plio-Pleistocene). A consequence of this history is that animals and plants inhabiting the South of the continent had a long period of time in which to adapt to arid, unstable climatic conditions. When parts of East Africa became arid during the Late Miocene and Plio-Pleistocene, several of these lineages expanded northwards and occupied developing arid niches before local lineages could adapt. Several of the latter became extinct, while others withdrew westwards as the tropical forest diminished in extent. It is proposed that the history of desertification in Africa was related to that of the polar ice caps (Antarctic, Arctic).

  1. A Drying Trend in Central Equatorial Africa

    NASA Astrophysics Data System (ADS)

    Diem, J.; Hartter, J.; Ryan, S. J.; Palace, M. W.

    2013-12-01

    There has been considerable uncertainty about changes in rainfall over central equatorial Africa over the past three decades due to a lack of reliable rainfall data in the region. This region contains the northern portion of the Albertine Rift, which is one of the world's hotspots for biodiversity, and within this region there is an exploding human population dependent on rainfed agriculture. Both the human population and conservation/preservation areas are becoming increasingly sensitive to changes in rainfall. There now exists an accurate, high-resolution, satellite based precipitation dataset, African Rainfall Climatology version 2 (ARC2), for the region that provides daily rainfall estimates from 1983 to the present. Here we show significant declines in monthly and annual rainfall in west-central Uganda, which exists in the far northeastern portion of the Rift, from 1983-2012. The decrease in annual rainfall was 110 mm per decade. Therefore, the current annual rainfall of approximately 1,200 mm is less than 80% of the annual rainfall three decades ago. The drying trend most likely extended westward into the Congo Basin. There were significant increasing (decreasing) trends in light-rainfall (heavy-rainfall) days over the period. Using results from previous studies, Indian Ocean warming and increasing carbonaceous aerosols from biomass burning in tropical Africa, are explored as potential causes of the drying trend. The aim of the study is not to find the fingerprint of local and regional anthropogenic forcings on the drying trend, but our results suggest that those forcings could be a leading cause of the drying trend.

  2. The Atlantic Climate Change Program

    SciTech Connect

    Molinari, R.L. ); Battisti, D. ); Bryan, K. ); Walsh, J. )

    1994-07-01

    The Atlantic Climate Change Program (ACCP) is a component of NOAA's Climate and Global Change Program. ACCP is directed at determining the role of the thermohaline circulation of the Atlantic Ocean on global atmospheric climate. Efforts and progress in four ACCP elements are described. Advances include (1) descriptions of decadal and longer-term variability in the coupled ocean-atmosphere-ice system of the North Atlantic; (2) development of tools needed to perform long-term model runs of coupled simulations of North Atlantic air-sea interaction; (3) definition of mean and time-dependent characteristics of the thermohaline circulation; and (4) development of monitoring strategies for various elements of the thermohaline circulation. 20 refs., 4 figs., 1 tab.

  3. North Atlantic Deep Water Formation

    NASA Technical Reports Server (NTRS)

    Bennett, T. (Editor); Broecker, W. S. (Editor); Hansen, J. (Editor)

    1984-01-01

    Various studies concerning differing aspects of the North Atlantic are presented. The three major topics under which the works are classified include: (1) oceanography; (2) paleoclimate; and (3) ocean, ice and climate modeling.

  4. North Atlantic Coastal Tidal Wetlands

    EPA Science Inventory

    The book chapter provides college instructors, researchers, graduate and advanced undergraduate students, and environmental consultants interested in wetlands with foundation information on the ecology and conservation concerns of North Atlantic coastal wetlands. The book c...

  5. Dual Hurricanes in the Atlantic

    NASA Video Gallery

    Cameras on the International Space Station show views of Hurricane Julia and Hurricane Igor, both moving west-northwest across the Atlantic on Sept. 14, 2010. At the time the video was captured, Ju...

  6. Effects Of The Thermohaline Circulation Slowdown On Vegetation And Climate Around The Tropical Atlantic During The Younger Dryas Period

    NASA Astrophysics Data System (ADS)

    Hermann, B.; Lydie, D. M.

    2005-12-01

    The Younger Dryas (YD) event is thought to be caused by a slowdown of the thermohaline circulation as a result of large input of freshwater into the Arctic Ocean (Tarasov and Peltier 2005). Decreased heat transport to the Arctic region would have resulted in higher sea surface temperatures of the tropical Atlantic (Rühlemann et al. 1999). Modelling studies show that a weaker Atlantic overturning circulation thus has consequences for the amount and geographical distribution of rain fall over and around the tropical Atlantic (Lohmann 2003). According to this study, northern South America would have become drier and eastern Brazil wetter. No significant changes in rainfall were predicted for Africa. We test these predictions comparing pollen studies from Africa, South America and the tropical Atlantic. Terrestrial and marine pollen sequences record changes in the tropical vegetation which responds to changes in precipitation. In south and south-eastern Brazil, a transect of three pollen sequences document the southern limit of a positive precipitation anomaly during the latter part of the YD period (Behling et al. 2004, 2005, unpublished data). In Africa, a dry YD period is recorded in Nigeria and Ghana (Talbot and Johannessen 1992, Salzmann et al. 2002). However, in Cameroon (Maley and Brenac 1998) and offshore Angola (Dupont and Behling in press) vegetation records are unambiguous or do not show changes in precipitation regime during the YD period.

  7. Causes of mortality across different immigrant groups in Northeastern Italy

    PubMed Central

    Ferroni, Eliana; Pigato, Mara; Avossa, Francesco; Saugo, Mario

    2015-01-01

    Background. Despite massive immigration towards Southern Europe in the last two decades, data on mortality by cause among immigrants in Italy are scarce. The aim of this study was to investigate mortality from all and from specific causes of death among immigrants residing in the Veneto Region (Northeastern Italy). Methods. Mortality records for the period 2008–2013 were extracted from the regional archive of causes of death, whereas population data were obtained from the 2011 Italian census. Immigrants were grouped by area of provenience based on the information on country of citizenship available both in mortality and census data. Standardized Mortality Ratios (SMR) with 95% Confidence Intervals (CI) were computed for the period 2008–2013 in subjects aged 20–59 years, with rates of Italian citizens as a reference. Results. Overall mortality was reduced both in male (SMR 0.86, CI [0.80–0.92]) and female immigrants (SMR 0.72, CI [0.65–0.78]), although an increased risk was observed for subjects from Sub-Saharan Africa. Significantly raised SMR for circulatory diseases were found among Sub-Saharan Africans and Southern Asians in both genders. Sub-Saharan Africans experienced a higher risk of death, especially from cerebrovascular diseases: SMR 4.78 (CI [2.67–7.89]) and SMR 6.09 (CI [1.96–14.2]) in males and females, respectively. Among Southern Asians, the increase in mortality from ischemic heart diseases reached statistical significance in males (SMR 2.53, CI [1.42–4.18]). In spite of a lower risk of death for all neoplasms combined, mortality from cancer of cervix uteri was increased among immigrants (SMR 2.61, CI [1.35–4.56]), as well as for other cancer sites in selected immigrant groups. A raised mortality was found for infectious diseases in Sub-Saharan Africans (both genders), and for transport accidents among females from Eastern Europe. Conclusion. Our study showed great variations in mortality by cause and area of provenience among

  8. Seismotectonics of northeastern United States and adjacent Canada

    NASA Astrophysics Data System (ADS)

    Yang, Jih-Ping; Aggarwal, Yash Pal

    1981-06-01

    Data for local earthquakes recorded by a network of stations in northeastern United States and adjacent Canada were analyzed to study the seismicity, the relationship between earthquakes and known faults, the state of stress, and crustal and upper mantle velocity structure. In addition, portable seismographs were deployed in the field to study aftershocks. As a result, accurate locations for about 364 local earthquakes (2 ≤ mb ≤ 5) and 22 focal mechanism solutions were determined. A comparison of the spatial distribution of these events (1970-1979) with historical earthquakes (1534-1959) reveals that seismic activity in the northeast is relatively stationary in space: those areas that have had little or no seismicity historically are relatively aseismic today, whereas the historically active areas are also active today. The instrumental locations, historical seismicity, and focal mechanism solutions show an internal consistency that help us distinguish two distinct seismogenic provinces. (1) The Adirondack-western Quebec province is a northwesterly trending zone of seismic activity, about 200 km wide and at least 500 km long, extending from the SE Adirondacks into western Quebec, Canada. Thrust faulting on planes striking NNW to NW appears to predominate, and the inferred axis of maximum horizontal compression is largely uniform and trends WSW, nearly parallel to the calculated absolute plate motion of North America. Little or no seismicity is found where anorthosite outcrops at the surface. Correlations between gravity anomalies and earthquake locations suggest that seismic activity in this zone is localized to regions of steep NE or SW gradient in Bouguer anomalies. This zone does not appear to extend southeastward to Boston, as proposed by some workers. (2) The Appalachian province is a northeasterly trending zone of seismic activity extending from northern Virginia to New Brunswick, Canada. Highangle reverse or thrust faulting on N to NE trending planes

  9. Evidence for episodic acidification effects on migrating Atlantic salmon Salmo salar smolts.

    PubMed

    Kelly, J T; Lerner, D T; O'Dea, M F; Regish, A M; Monette, M Y; Hawkes, J P; Nislow, K H; McCormick, S D

    2015-11-01

    Field studies were conducted to determine levels of gill aluminium as an index of acidification effects on migrating Atlantic salmon Salmo salar smolts in the north-eastern U.S.A. along mainstem river migration corridors in several major river basins. Smolts emigrating from the Connecticut River, where most (but not all) tributaries were well buffered, had low or undetectable levels of gill aluminium and high gill Na(+) /K(+) -ATPase (NKA) activity. In contrast, smolts emigrating from the upper Merrimack River basin where most tributaries are characterized by low pH and high inorganic aluminium had consistently elevated gill aluminium and lower gill NKA activity, which may explain the low adult return rates of S. salar stocked into the upper Merrimack catchment. In the Sheepscot, Narraguagus and Penobscot Rivers in Maine, river and year-specific effects on gill aluminium were detected that appeared to be driven by underlying geology and high spring discharge. The results indicate that episodic acidification is affecting S. salar smolts in poorly buffered streams in New England and may help explain variation in S. salar survival and abundance among rivers and among years, with implications for the conservation and recovery of S. salar in the north-eastern U.S.A. These results suggest that the physiological condition of outmigrating smolts may serve as a large-scale sentinel of landscape-level recovery of atmospheric pollution in this and other parts of the North Atlantic region. PMID:26399385

  10. Pan-atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries.

    PubMed

    Fossette, S; Witt, M J; Miller, P; Nalovic, M A; Albareda, D; Almeida, A P; Broderick, A C; Chacón-Chaverri, D; Coyne, M S; Domingo, A; Eckert, S; Evans, D; Fallabrino, A; Ferraroli, S; Formia, A; Giffoni, B; Hays, G C; Hughes, G; Kelle, L; Leslie, A; López-Mendilaharsu, M; Luschi, P; Prosdocimi, L; Rodriguez-Heredia, S; Turny, A; Verhage, S; Godley, B J

    2014-04-01

    Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters. PMID:24523271

  11. Pan-Atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries

    PubMed Central

    Fossette, S.; Witt, M. J.; Miller, P.; Nalovic, M. A.; Albareda, D.; Almeida, A. P.; Broderick, A. C.; Chacón-Chaverri, D.; Coyne, M. S.; Domingo, A.; Eckert, S.; Evans, D.; Fallabrino, A.; Ferraroli, S.; Formia, A.; Giffoni, B.; Hays, G. C.; Hughes, G.; Kelle, L.; Leslie, A.; López-Mendilaharsu, M.; Luschi, P.; Prosdocimi, L.; Rodriguez-Heredia, S.; Turny, A.; Verhage, S.; Godley, B. J.

    2014-01-01

    Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters. PMID:24523271

  12. Transport of Biomass Burning Emissions from Southern Africa

    NASA Technical Reports Server (NTRS)

    Sinha, Parikhit; Jaegle,Lyatt; Hobbs, Peter V.; Liang, Qing

    2004-01-01

    The transport of biomass burning emissions from southern Africa to the neighboring Atlantic and Indian Oceans during the dry season (May-October) of 2000 is characterized using ground, ozonesonde, and aircraft measurements of carbon monoxide (CO) and ozone (O3) in and around southern Africa, together with the GEOS-CHEM global model of tropospheric chemistry. The model shows a positive bias of approximately 20% for CO and a negative bias of approximately 10-25% for O3 at oceanic sites downwind of fire emissions. Near areas of active fire emissions the model shows a negative bias of approximately 60% and approximately 30% for CO and O3, respectively, likely due to the coarse spatial (2 deg. x 2.5 deg.) and temporal (monthly) resolution of the model compared to that of active fires. On average, from 1994 to 2000, approximately 60 Tg of carbon monoxide (CO) from biomass burning in southern Africa was transported eastward to the Indian Ocean across the latitude band 0 deg. -60 S during the 6 months of the dry season. Over the same time period, approximately 40 Tg of CO from southern African biomass burning was transported westward to the Atlantic Ocean over the latitudes 0 deg. -20 S during the 6-month dry season, but most of that amount was transported back eastward over higher latitudes to the south (21 deg. -60 S). Eastward transport of biomass burning emissions from southern Africa enhances CO concentrations by approximately 4- 13 ppbv per month over the southern subtropical Indian Ocean during the dry season, with peak enhancements in September. Carbon monoxide from southern African and South American biomass burning is seen in the model simulations as far away as Australia, contributing approximately 8 ppbv and approximately 12-15 ppbv CO, respectively, and thus explaining the approximately 20- 25 ppbv observed enhancement of CO over Melbourne in mid-September 2000.

  13. Climate variability and predictability in Northwest Africa

    NASA Astrophysics Data System (ADS)

    Baddour, O.; Djellouli, Y.

    2003-04-01

    Northwest Africa defined here as the area including Morocco, Algeria and Tunisia, occupies a large territory in North Africa with an area exceeding 3.5 million km2. The geographical contrast is very important: while most of the southern part is desert, the northern and northwestern parts exhibit a contrasting geography including large flat areas in the western part of Morocco, northern Algeria and eastern part of Tunisia and the formidable Atlas mountains barrier extends from south west of Morocco toward north west of Tunisia crossing central Morocco and north Algeria. Agriculture is one of major socio-economic activities in the region with an extensive cash-crop for exporting to Europe especially from Morocco and Tunisia. The influence of the recurring droughts during the 80s and 90s was very crucial for the economic and societal aspects of the region. In Morocco, severe droughts have caused GDP fluctuation within past 20 years from 10% increase down to negative values in some particular years. Recent studies have investigated seasonal rainfall variability and prediction over MOROCCO in the framework of regional and international collaboration. Results from this work has shown that the main general circulation feature associated with the rainfall variability within Morocco is the North Atlantic Oscillation. The relationship is in fact due to the major role played by the AZORES high pressure with its role in modulating the main position of the active synoptic systems in the north Atlantic area and therefore in modulating the frequency and the intensity of the weather systems that impact the western part of the region. Mediterranean sea plays also major role in the mid of the region. In this paper we applied EOF technique on 500 hPa. The data used are monthly reanalysis NCEP/NCAR analyses for November from 1960 to 1990 climatological time series. Correlation analysis is then performed between EOF time series and global 4x4 degre SST anomalies. The results we

  14. On the North Atlantic circulation

    SciTech Connect

    Schmitz, W.J. Jr.; McCartney, M.S. )

    1993-02-01

    A summary for North Atlantic circulation is proposed to replace the circulation scheme hypothesized by Worthington in 1976. Divergences from the previous model are in thermohaline circulation, cross-equatorical transport and Florida Current sources, flow in the eastern Atlantic, circulation in the Newfoundland Basin, slope water currents, and flow pattern near the Bahamas. The circulation patterns presented here are consistent with the majority of of published accounts of flow components. 77 refs., 14 figs., 3 tabs.

  15. Millennial-Scale ITCZ Variability in the Tropical Atlantic and Dynamics of Amazonian Rain Forest

    NASA Astrophysics Data System (ADS)

    Wang, X.; Auler, A. S.; Edwards, R. L.; Cheng, H.; Shen, C.; Smart, P. L.; Richards, D. A.

    2003-12-01

    Precipitation in the Amazon Basin is largely related to the intertropical convergence zone (ITCZ) in the tropical Atlantic which undergoes a regular seasonal migration. We chose a site south of the present day rainforest in semiarid northeastern Brazil, in order to study the timing of pluvial periods when the southern extend of the ITCZ would have been much further south than today. Shifts in the ITCZ position may have influenced the dynamics of rain forest and species diversity. We collected speleothems from northern Bahia state, located southeast of Amazonia. Age determinations with U-series dating methods show that samples grew rapidly during relatively short intervals (several hundreds of years) of glacial periods in the last 210 kyr. In addition, paleopluvial phases delineated by speleothem growth intervals show millennial-scale variations. Pluvial phases coincide with the timing of weak East Asian summer monsoon intensities (Wang et al., 2001, Science 294: 2345-2348), which have been correlated to the timing of stadials in Greenland ice core records and Heinrich events (Bond and Lotti, 1995, Science 267: 1005-1010). Furthermore, these intervals correspond to the periods of light color reflectance of Cariaco Basin sediments from ODP Hole 1002C (Peterson et al., 2000, Science, 290: 1947-1951), which was suggested to be caused by a southward shift of the northernmost position of the ITCZ and decreased rainfall in this region. Abrupt precipitation changes in northeastern Brazil may be due to the southward displacement of the southernmost position of the ITCZ associated with atmosphere-ocean circulation changes caused by (1) an increase in northern high latitude-tropical temperature gradient (Chiang et al., 2003, Paleoceanography, in press), and/or (2) the bipolar seesaw mechanism (Broecker et al., 1998, Paleoceanography 13: 119-121) during these Heinrich events. Pluvial phases are also coincident with higher insolation at 10° S during austral autumn. This

  16. South Atlantic Spreading Velocities and Time Scales

    NASA Astrophysics Data System (ADS)

    Clark, S. R.; Smethurst, M. A.; Bianchi, M. C.

    2013-12-01

    Plate reconstructions based on hierarchical spherical rotations have been around for many years. For the breakup of Pangea and Gondwana, these reconstructions are based on two major sources: magnetic isochrons and geological evidence for the onset of rifting and the tightness of the fit between continents. These reconstructions imply spreading velocities and it is the changes in velocities that can be used to probe questions of the forces moving plates around. In order to calculate the velocities correctly though, the importance of the choice of geologic time scale is often ignored. In this talk, we focus on the South Atlantic and calculate the spreading velocity errors implied by the choice of time scale for three major epochs: the Cenozoic and Late Mesozoic, the Cretaceous Quiet Zone and the Late Cretaceous to the Early Jurassic. In addition, we report the spreading velocities implied through these phases by various available magnetic isochron-derived reconstructions and the geological fits for South America and Africa used by large scale global reconstruction as well as in recent papers. Finally, we will highlight the implications for the choice of the mantle reference frame on African plate velocities.

  17. The North Atlantic Cold Bias

    NASA Astrophysics Data System (ADS)

    Greatbatch, Richard; Drews, Annika; Ding, Hui; Latif, Mojib; Park, Wonsun

    2016-04-01

    The North Atlantic cold bias, associated with a too zonal path of the North Atlantic Current and a missing "northwest corner", is a common problem in coupled climate and forecast models. The bias affects the North Atlantic and European climate mean state, variability and predictability. We investigate the use of a flow field correction to adjust the path of the North Atlantic Current as well as additional corrections to the surface heat and freshwater fluxes. Results using the Kiel Climate Model show that the flow field correction allows a northward flow into the northwest corner, largely eliminating the bias below the surface layer. A surface cold bias remains but can be eliminated by additionally correcting the surface freshwater flux, without adjusting the surface heat flux seen by the ocean model. A model version in which only the surface fluxes of heat and freshwater are corrected continues to exhibit the incorrect path of the North Atlantic Current and a strong subsurface bias. Removing the bias impacts the multi-decadal time scale variability in the model and leads to a better representation of the SST pattern associated with the Atlantic Multidecadal Variability than the uncorrected model.

  18. A Phororhacoid bird from the Eocene of Africa

    NASA Astrophysics Data System (ADS)

    Mourer-Chauviré, Cécile; Tabuce, Rodolphe; Mahboubi, M'hammed; Adaci, Mohammed; Bensalah, Mustapha

    2011-10-01

    The bird fossil record is globally scarce in Africa. The early Tertiary evolution of terrestrial birds is virtually unknown in that continent. Here, we report on a femur of a large terrestrial new genus discovered from the early or early middle Eocene (between ˜52 and 46 Ma) of south-western Algeria. This femur shows all the morphological features of the Phororhacoidea, the so-called Terror Birds. Most of the phororhacoids were indeed large, or even gigantic, flightless predators or scavengers with no close modern analogs. It is likely that this extinct group originated in South America, where they are known from the late Paleocene to the late Pleistocene (˜59 to 0.01 Ma). The presence of a phororhacoid bird in Africa cannot be explained by a vicariant mechanism because these birds first appeared in South America well after the onset of the mid-Cretaceous Gondwana break up (˜100 million years old). Here, we propose two hypotheses to account for this occurrence, either an early dispersal of small members of this group, which were still able of a limited flight, or a transoceanic migration of flightless birds from South America to Africa during the Paleocene or earliest Eocene. Paleogeographic reconstructions of the South Atlantic Ocean suggest the existence of several islands of considerable size between South America and Africa during the early Tertiary, which could have helped a transatlantic dispersal of phororhacoids.

  19. Out of Africa: the slow train to australasia.

    PubMed

    Waters, Jonathan M; Roy, Michael S

    2004-02-01

    We used mitochondrial DNA (mtDNA) sequences to test biogeographic hypotheses for Patiriella exigua (Asterinidae), one of the world's most widespread coastal sea stars. This small intertidal species has an entirely benthic life history and yet occurs in southern temperate waters of the Atlantic, Indian, and Pacific oceans. Despite its abundance around southern Africa, southeastern Australia, and several oceanic islands, P. exigua is absent from the shores of Western Australia, New Zealand, and South America. Phylogenetic analysis of mtDNA sequences (cytochrome oxidase I, control region) indicates that South Africa houses an assemblage of P. exigua that is not monophyletic (P = 0.04), whereas Australian and Lord Howe Island specimens form an interior monophyletic group. The placement of the root in Africa and small genetic divergences between eastern African and Australian haplotypes strongly suggest Pleistocene dispersal eastward across the Indian Ocean. Dispersal was probably achieved by rafting on wood or macroalgae, which was facilitated by the West Wind Drift. Genetic data also support Pleistocene colonization of oceanic islands (Lord Howe Island, Amsterdam Island, St. Helena). Although many biogeographers have speculated about the role of long-distance rafting, this study is one of the first to provide convincing evidence. The marked phylogeographic structure evident across small geographic scales in Australia and South Africa indicates that gene flow among populations may be generally insufficient to prevent the local evolution of monophyly. We suggest that P. exigua may rely on passive mechanisms of dispersal. PMID:14965897

  20. Geographical distribution of pelagic decapod shrimp in the Atlantic Ocean.

    PubMed

    Judkins, David C

    2014-01-01

    Ninety-one species of pelagic decapod shrimp were identified in 938 midwater-trawl collections taken between 1963 and 1974 from the North and South Atlantic. Distributional maps are provided for the most frequently occurring species. Nighttime abundance of most species was greatest within the upper 200 m. Degree of geographical overlap was estimated using the geometric mean of the proportion of joint occurrences with a value ≥ 0.5 deemed significant. Geographical distributions tended to be unique, and only 31 species had values ≥ 0.5 with one or more other species. Species within genera and within phylogenetic subgroups of Sergia were generally parapatric or partially overlapping in distribution. Five geographical groupings of co-occurring species across genera were identified: Subpolar-Temperate, Southern Hemisphere, Central, Tropical, Eastern Tropical and Western Tropical. The two species of the Southern Hemisphere group are circumpolar at temperate latitudes. The 12 species of the Central group occurred throughout the subtropical and tropical North and South Atlantic. The eight species of the Tropical group occurred broadly across the equatorial Atlantic and Caribbean with ranges usually extending into the Gulf of Mexico and northward in the Gulf Stream. The two species of the Western Tropical group occurred most often in the western tropics, but there were scattered occurrences at subtropical latitudes. The four species of the Eastern Tropical group were endemic to the Mauritanian Upwelling and the Angola-Benguela Frontal zones off western Africa. Two of the three species in the Subpolar-Temperate group had bipolar distributions, and all three occurred in the Mediterranean and in the Mauritanian Upwelling zone. Most Central, Tropical and Western Tropical species were present in the in the Gulf of Mexico. The 10 species from the Mediterranean were a mixture of Subpolar-Temperate, Central and benthopelagic species. Patterns of distribution in Atlantic pelagic

  1. FACING SOUTHWEST OF NORTHEASTERN CORNER OF PARK FROM INTERSECTION OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACING SOUTHWEST OF NORTHEASTERN CORNER OF PARK FROM INTERSECTION OF TERRACE AVENUE AND CLIFTON ROAD - Candler Park Historic District, Roughly bounded by Moreland, Dekalb, McLendon & Harold Avenues, Matthews Street & Clifton Terrace, Atlanta, Fulton County, GA

  2. 14. HALLWAY, THIRD FLOORShowing the offices on the front (northeastern) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. HALLWAY, THIRD FLOOR--Showing the offices on the front (northeastern) side of the building. North - Empire Building, 430 Sixteenth Street, South Corner of Sixteenth Street & Glenarm Place, Denver, Denver County, CO

  3. 4. VIEW OF NORTHEASTERN APPROACH TO GEORGIA DOT BRIDGE NO. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW OF NORTHEASTERN APPROACH TO GEORGIA DOT BRIDGE NO. 111-00060P-00020N - Georgia DOT Bridge No. 111-00060P-00020N, Georgia State Route 60 spur spanning Hempton Creek, Mineral Bluff, Fannin County, GA

  4. Landscape Thresholds and the Condition of Northeastern Estuaries

    EPA Science Inventory

    Anthropogenic impacts to northeastern estuaries have been well documented and many researchers have quantified the associations between broad scale human land uses in contributing landscapes and impacted estuarine condition. However, associations alone are not adequate for ident...

  5. IS NITROGEN DEPOSITION ALTERING THE NITROGEN STATUS OF NORTHEASTERN FORESTS?

    EPA Science Inventory

    This paper reviews literature and compiles existing data to address the question "Is N deposition altering the N status in Northeastern forests?" Using correlational techniques and large sample size, three different categories of indicators appear to give different results. The...

  6. 12. REINFORCED CONCRETE SLAB ROOF FROM NORTHEASTERN EDGE, VIEW TOWARDS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. REINFORCED CONCRETE SLAB ROOF FROM NORTHEASTERN EDGE, VIEW TOWARDS SOUTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  7. Childhood cancer in Africa.

    PubMed

    Kruger, Mariana; Hendricks, Marc; Davidson, Alan; Stefan, Cristina D; van Eyssen, Ann L; Uys, Ronelle; van Zyl, Anel; Hesseling, Peter

    2014-04-01

    The majority of children with cancer live in low- and middle-income countries (LMICs) with little or no access to cancer treatment. The purpose of the paper is to describe the current status of childhood cancer treatment in Africa, as documented in publications, dedicated websites and information collected through surveys. Successful twinning programmes, like those in Malawi and Cameroon, as well as the collaborative clinical trial approach of the Franco-African Childhood Cancer Group (GFAOP), provide good models for childhood cancer treatment. The overview will hopefully influence health-care policies to facilitate access to cancer care for all children in Africa. PMID:24214130

  8. Hematology in Africa.

    PubMed

    Makani, Julie; Roberts, David J

    2016-04-01

    This review of hematology in Africa highlights areas of current practice and the immediate needs for development and clinical research. Acute hematological practice is dominated by anemia, sickle cell disease, and the need to provide a safe and rapidly available supply of blood. There is a growing need for specialist services for bleeding and coagulation, hematological malignancy, and palliative care. There are many areas of practice where straightforward measures could yield large gains in patient care. There is an urgent need for good clinical research to describe the epidemiology, natural history, and management of hematological diseases in Africa. PMID:27040965

  9. Family Planning Programmes in Africa.

    ERIC Educational Resources Information Center

    Pradervand, Pierre

    The countries discussed in this paper are the francophone countries of West Africa and the Republic of Congo, with comparative references made to North Africa (mainly Morocco, Algeria, and Tunisia). Obstacles to the adoption of family planning in the countries of tropical Africa are a very high mortality rate among children; a socioeconomic…

  10. Telecommunications and Development in Africa.

    ERIC Educational Resources Information Center

    Kiplagat, B. A., Ed.; Werner, M. C. M., Ed.

    The Telecommunications Foundation of Africa (TFA) was created in 1992 out of a conviction that insufficient telecommunications in Africa are an impediment to economic growth, and that more resources could be mobilized to strengthen this sector. This volume was made by TFA for readers both inside and outside of Africa and the telecommunications…

  11. Country Energy Profile, South Africa

    SciTech Connect

    1995-08-01

    This country energy profile provides energy and economic information about South Africa. Areas covered include: Economics, demographics, and environment; Energy situation; Energy structure; Energy investment opportunities; Department of Energy (DOE) programs in South Africa; and a listing of International aid to South Africa.

  12. Impacts of interstate transport of pollutants on high ozone events over the Mid-Atlantic United States

    NASA Astrophysics Data System (ADS)

    Liao, Kuo-Jen; Hou, Xiangting; Baker, Debra Ratterman

    2014-02-01

    The impacts of interstate transport of anthropogenic nitrogen oxides (NOx) and volatile organic compound (VOC) emissions on peak ozone formation in four nonattainment areas (i.e., Baltimore, Philadelphia-Wilmington-Atlantic City, Pittsburgh-Beaver Valley and Washington, DC) in the Mid-Atlantic U.S. were quantified in this study. Regional air quality and sensitivities of ground-level ozone to emissions from four regions in the eastern U.S. were simulated for three summer months (June, July and August) in 2007 using the U.S. EPA's Community Multiscale Air Quality model with the decoupled direct method 3D. The emissions inventory used in this study was the 2007 Mid-Atlantic Regional Air Management Association Level 2 inventory, developed for State Implementation Plan screening modeling for the Ozone Transport Commission region. The modeling results show that responses of peak ozone levels at specific locations to emissions from EGU (i.e., electric generating unit) and non-EGU sources could be different. Therefore, emissions from EGU and non-EGU sources should be considered as two different control categories when developing regional air pollution mitigation strategies. Based on the emission inventories used in this study, reductions in anthropogenic NOx emissions (including those from EGU and non-EGU sources) from the Great Lake region as well as northeastern and southeastern U.S. would be effective for decreasing area-mean peak ozone concentrations during the summer of 2007 in the Mid-Atlantic ozone air quality nonattainment areas. The results also show that reductions in anthropogenic VOC emissions from the northeastern U.S. would also be effective for decreasing area-mean peak ozone concentrations over the Mid-Atlantic U.S. In some cases, reductions in anthropogenic NOx emissions from the Great Lake and northeastern U.S. could slightly increase area-mean peak ozone concentrations at some ozone monitors in the Pittsburgh-Beaver Valley and Washington, DC areas

  13. The Cretaceous (Cenomanian) continental record of the Laje do Coringa flagstone (Alcântara Formation), northeastern South America

    NASA Astrophysics Data System (ADS)

    Medeiros, Manuel Alfredo; Lindoso, Rafael Matos; Mendes, Ighor Dienes; Carvalho, Ismar de Souza

    2014-08-01

    The fossil taxa of the Cenomanian continental flora and fauna of São Luís Basin are observed primarily in the bone bed of the Laje do Coringa, Alcântara Formation. Many of the disarticulated fish and tetrapod skeletal and dental elements are remarkably similar to the chronocorrelate fauna of Northern Africa. In this study, we present a summary of the continental flora and fauna of the Laje do Coringa bone-bed. The record emphasizes the existence of a trans-oceanic typical fauna, at least until the early Cenomanian, which may be interpreted as minor evolutionary changes after a major vicariant event or as a result of a land bridge across the equatorial Atlantic Ocean, thereby allowing interchanges between South America and Africa. The paleoenvironmental conditions in the northern Maranhão State coast during that time were inferred as forested humid areas surrounded by an arid to semi-arid landscape.

  14. Breakup of Pangaea and plate kinematics of the central Atlantic and Atlas regions

    NASA Astrophysics Data System (ADS)

    Schettino, Antonio; Turco, Eugenio

    2009-08-01

    A new central Pangaea fit (type A) is proposed for the late Ladinian (230 Ma), together with a plate motions model for the subsequent phases of rifting, continental breakup and initial spreading in the central Atlantic. This model is based on: (1) a reinterpretation of the process of formation of the East Coast Magnetic Anomaly along the eastern margin of North America and the corresponding magnetic anomalies at the conjugate margins of northwest Africa and the Moroccan Meseta; (2) an analysis of major rifting events in the central Atlantic, Atlas and central Mediterranean and (3) a crustal balancing of the stretched margins of North America, Moroccan Meseta and northwest Africa. The process of fragmentation of central Pangaea can be described by three major phases spanning the time interval from the late Ladinian (230 Ma) to the Tithonian (147.7 Ma). During the first phase, from the late Ladinian (230 Ma) to the latest Rhaetian (200 Ma), rifting proceeded along the eastern margin of North America, the northwest African margin and the High, Saharan and Tunisian Atlas, determining the formation of a separate Moroccan microplate at the interface between Gondwana and Laurasia. During the second phase, from the latest Rhaetian (200 Ma) to the late Pliensbachian (185 Ma), oceanic crust started forming between the East Coast and Blake Spur magnetic anomalies, whereas the Morrocan Meseta simply continued to rift away from North America. During this time interval, the Atlas rift reached its maximum extent. Finally, the third phase, encompassing the time interval from the late Pliensbachian (185 Ma) to chron M21 (147.7 Ma), was triggered by the northward jump of the main plate boundary connecting the central Atlantic with the Tethys area. Therefore, as soon as rifting in the Atlas zone ceased, plate motion started along complex fault systems between Morocco and Iberia, whereas a rift/drift transition occurred in the northern segment of the central Atlantic, between Morocco

  15. Changes in dominant moisture sources and the consequences for hydroclimate on the northeastern Tibetan Plateau during the past 32 kyr

    NASA Astrophysics Data System (ADS)

    Thomas, Elizabeth K.; Huang, Yongsong; Clemens, Steven C.; Colman, Steven M.; Morrill, Carrie; Wegener, Pamela; Zhao, Jiangtao

    2016-01-01

    Lake Qinghai, located on the northeastern Tibetan Plateau north of the modern maximum summer monsoon extent, is well situated to record northward advances of the summer monsoon. Existing paleoclimate records contain conflicting evidence for the timing of summer monsoon advance into this region: an early arrival pre-Younger Dryas or a late arrival at the beginning of the Holocene. A 30-kyr-long leaf wax hydrogen isotope (n-alkanoic acid, δ2Hwax) record from Lake Qinghai helps to address this discrepancy by elucidating changes in the three main moisture sources in this region: southerly (summer monsoon), northwesterly, and local precipitation. Lake Qinghai δ2Hwax indicates that the arid glacial period was dominated by northwesterly moisture. Extremely arid conditions prevailed from 15 to 14 ka, likely because westerly winds were weakening and the summer monsoon had not yet reached this region. This arid period ended by 13.6 ka when small amounts of summer monsoon precipitation reached Lake Qinghai. Summer monsoon moisture subsequently retreated off of the northeastern Tibetan Plateau during the Younger Dryas and re-advanced in the early Holocene. Summer monsoon precipitation decreased progressively throughout the Holocene in response to decreasing summer insolation, and the modern northwesterly- and local-dominated moisture regime was attained ca. 2.6 ka. Lake Qinghai δ2Hwax demonstrates that the summer monsoon extent was dynamic during the past 30 kyr, responding dramatically to insolation and North Atlantic circulation changes. Moreover, Lake Qinghai δ2Hwax demonstrates that local and northwesterly air masses are important moisture sources to the northeastern Tibetan Plateau, and should be considered when reconstructing past hydroclimate in this region.

  16. Smoke in Southern Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This SeaWiFS true-color image acquired over Southern Africa on Sept. 4, 2000, shows a thick shroud of smoke and haze blanketing much of the southern half of the continent. The smoke in this scene is being generated by a tremendous number of fires burning over a large area across the countries of Angola, Zambia, Mozambique, Zimbabwe, Botswana, and the Northern Province of South Africa. In this image, the smoke (grey pixels) is easily distinguished from clouds (bright white pixels). Refer to the Images and Data section for a larger scale view of the fires in Southern Africa. Data from both the SeaWiFS and Terra satellites are being used by an international team of scientists participating in the SAFARI field experiment. The objective of SAFARI is to measure the effects of windblown smoke and dust on air quality and the Earth's radiant energy budget. This image was produced using SeaWiFS channels 6, 5, and 1 (centered at 670 nm, 555 nm , and 412 nm, respectively). The data were acquired and provided by the Satellite Applications Center in Pretoria, South Africa. Image courtesy Gene Feldman, SeaWiFS Project and Orbital Sciences

  17. Africa: Myth and Reality.

    ERIC Educational Resources Information Center

    Brown, Barbara B.

    1994-01-01

    Reports on the Third International Social Studies Conference held in Nairobi, Kenya, in 1994. Discusses democracy, educational reform efforts, and the importance of tourism to the Kenyan economy. Asserts that U.S. teachers must use accurate and nonstereotypical instructional materials in teaching about Africa. (CFR)

  18. Education in Africa.

    ERIC Educational Resources Information Center

    Educational Documentation and Information, 1977

    1977-01-01

    This selected, annotated bibliography of information resources in English and/or French is divided into sections on books; documents and articles; UNESCO publications; reference works; and African periodicals. A list of institutions concerned with education in Africa is included, as well as educational documentation and information services in…

  19. AED in Africa

    ERIC Educational Resources Information Center

    Academy for Educational Development, 2004

    2004-01-01

    Founded in 1961, the Academy for Educational Development (AED) is an independent, nonprofit, charitable organization that operates development programs in the United States and throughout the world. This directory presents an overview of the AED programs in Africa since 1975. Current AED Programs include: (1) HIV/AIDS Prevention and Impact…

  20. AIDS and Africa. Introduction.

    PubMed

    Kopelman, Loretta M; van Niekerk, Anton A

    2002-04-01

    Sub-Saharan Africa is the epicenter of the HIV/AIDS epidemic, and in this issue of the Journal, seven authors discuss the moral, social and medical implications of having 70% of those stricken living in this area. Anton A. van Niekerk considers complexities of plague in this region (poverty, denial, poor leadership, illiteracy, women's vulnerability, and disenchantment of intimacy) and the importance of finding responses that empower its people. Solomon Benatar reinforces these issues, but also discusses the role of global politics in sub-Saharan Africa, especially discrimination, imperialism and its exploitation by first world countries. Given the public health crisis, Udo Schüklenk and Richard E. Ashcroft defend compulsory licensing of essential HIV/AIDS medications on consequentialist grounds. Keymanthri Moodley discusses the importance of conducting research and the need to understand a moderate form of communitarianism, also referred to as "ubuntu" or "communalism", to help some Africans understand research as an altruistic endeavour. Godfrey B. Tangwa also defends traditional African values of empathy and ubuntu, discussing how they should be enlisted to fight this pandemic. Loretta M. Kopelman criticizes the tendency among those outside Africa to dismiss the HIV/AIDS pandemic, attributing one source to the ubiquitous and misguided punishment theory of disease. The authors conclude that good solutions must be cooperative ventures among countries within and outside of sub-Saharan Africa with far more support from wealthy countries. PMID:11961693

  1. Anglicising Postapartheid South Africa

    ERIC Educational Resources Information Center

    Louw, P. Eric

    2004-01-01

    The apartheid state deliberately encouraged linguistic diversity and actively built cultural infrastructures which impeded Anglicisation. With the end of apartheid has come "de facto" Anglicisation. So although South Africa has, since 1994, had 11 official languages, in reality, English is swamping the other 10 languages. Afrikaans has, in…

  2. Pythiosis in Africa

    PubMed Central

    Rivierre, Christine; Laprie, Caroline; Guiard-Marigny, Olivier; Bergeaud, Patrick; Berthelemy, Madeleine

    2005-01-01

    We report the first case of pythiosis from Africa in an 8-month-old dog with a chronic and ulcerative cutaneous lesion. The etiologic agent belonged to the genus Pythium. Phylogenetic analysis placed the isolate in a sister group to the other P. insidiosum strains. However, the isolate may belong to a new Pythium species. PMID:15757572

  3. Photomontage. Water in Africa.

    ERIC Educational Resources Information Center

    McKoski, David

    The Water in Africa Project was realized over a 2-year period by a team of Peace Corps volunteers. As part of an expanded, detailed design, resources were collected from over 90 volunteers serving in African countries, photos and stories were prepared, and standards-based learning units were created for K-12 students. This unit, "Photomontage,"…

  4. Who Speaks for Africa?

    ERIC Educational Resources Information Center

    Nealy, Michelle

    2005-01-01

    Judging by the press coverage, it would seem that Europeans are the only ones concerned about conditions in Africa, but perhaps the media is not telling the whole story. According to Mark P. Fancher, chair of the National Conference of Black Lawyers' Section on International Affairs & World Peace and the author of "The Splintering of Global…

  5. Africa and Applied Linguistics.

    ERIC Educational Resources Information Center

    Makoni, Sinfree, Ed.; Meinhof, Ulrike H., Ed.

    2003-01-01

    This collection of articles includes: "Introducing Applied Linguistics in Africa" (Sinfree Makoni and Ulrike H. Meinhof); "Language Ideology and Politics: A Critical Appraisal of French as Second Official Language in Nigeria" (Tope Omoniyi); "The Democratisation of Indigenous Languages: The Case of Malawi" (Themba Moyo); "Classroom Code-Switching…

  6. Anatomy: Spotlight on Africa

    ERIC Educational Resources Information Center

    Kramer, Beverley; Pather, Nalini; Ihunwo, Amadi O.

    2008-01-01

    Anatomy departments across Africa were surveyed regarding the type of curriculum and method of delivery of their medical courses. While the response rate was low, African anatomy departments appear to be in line with the rest of the world in that many have introduced problem based learning, have hours that are within the range of western medical…

  7. Neonatal surgery in Africa.

    PubMed

    Chirdan, Lohfa B; Ngiloi, Petronilla J; Elhalaby, Essam A

    2012-05-01

    The management of neonatal surgical problems continues to pose considerable challenges, particularly in low-resource settings. The burden of neonatal surgical diseases in Africa is not well documented. The characteristics of some neonatal surgical problems are highlighted. Late presentation coupled with poor understanding of the milieu interior of the neonates by incompetent health care providers and poorly equipped hospitals combine to give rise to the unacceptable high morbidity and mortality in most parts of Africa. Proper training of all staff involved in neonatal health care coupled with community awareness must be vigorously pursued by all stakeholders. Various governments throughout the continent of Africa, in conjunction with international donor agencies, must not only provide an adequate budget for health care services and improve infrastructures, but must also deliberately encourage and provide funding for neonatal surgical care and research across the continent. The well-established pediatric surgical training programs, particularly in North and South Africa, should hold the moral responsibility of training all possible numbers of young surgeons from other African countries that do not have any existing pediatric surgical training programs or those countries suffering from remarkable shortage of trained pediatric surgeons. PMID:22475121

  8. Out of Africa

    ERIC Educational Resources Information Center

    Wilbert, Nancy Corrigan

    2009-01-01

    Karen Blixen (Isak Dinesen), author of "Out of Africa," said, "God made the world round so people would never be able to see too far down the road." The author embraced this wonderful thought by venturing on a three-week journey to Kenya and Tanzania in search of grand adventure. In this article, the author shares her adventure with her students…

  9. AED in Africa.

    ERIC Educational Resources Information Center

    Academy for Educational Development, Washington, DC.

    For 30 years, the Academy for Educational Development (AED) has worked to support African development. In Uganda, Tanzania, and Botswana AED promoted some of Africa's first AIDS prevention programs. AED is funding research in Ethiopia, Tanzania, and perhaps Zambia that will target stigma and its role in AIDS prevention. Working with governments…

  10. Topical Research: Africa.

    ERIC Educational Resources Information Center

    Lynn, Karen

    This lesson plan can be used in social studies, language arts, or library research. The instructional objective is for students to select a topic of study relating to Africa, write a thesis statement, collect information from media sources, and develop a conclusion. The teacher may assign the lesson for written or oral evaluation. The teacher…

  11. Libraries in Africa.

    ERIC Educational Resources Information Center

    Enyia, Christian O.; And Others

    1991-01-01

    Includes five articles that discuss library and information work in Africa. Highlights include computerization in Nigerian libraries; education for library and information services in Ghana; an evaluation of African librarianship; the role of Nigerian publishers in national development; and the role of information services in national development…

  12. Boninites: Characteristics and tectonic constraints, northeastern Appalachians

    USGS Publications Warehouse

    Kim, J.; Jacobi, R.D.

    2002-01-01

    Boninites are high Mg andesites that are thought to form in suprasubduction zone tectonic environments as primary melts from refractory mantle. Boninites provide a potential constraint on tectonic models for ancient terranes that contain boninites because the only unequivocal tectonic setting in which "modern" boninites have been recognized is a fore-arc setting. Tectonic models for "modern" boninite genesis include subduction initiation ("infant arc"), fore-arc spreading, and the forearc side of intra-arc rifting (spreading). These models can be differentiated by the relative age of the boninites and to a lesser degree, geochemistry. The distinctive geochemistry of boninites promotes their recognition in ancient terranes. As detailed in this report, several mafic terranes in the northeastern Appalachians contain boninites; these terranes were situated on both sides of Iapetus. The characteristics of these boninites can be used to constrain tectonic models of the evolution of the northeastern Appalachians. On the Laurentian side of Iapetus, "infant arc" boninites were not produced ubiquitously during the Cambrian subduction initiation, unless sampling problems or minimum age dates obscure a more widespread boninite "infant arc". The Cambrian subduction initiation on the Laurentian side was probably characterized by both "infant arc" boninitic arc construction (perhaps the >496 Ma Hawley Formation and the >488 Ma Betts Cove Ophiolite) and "normal" arc construction (Mt. Orford). This duality is consistent with the suggestion that the pre-collisional geometry of the Laurentian margin was complex. The Bay of Islands Complex and Thetford Mines ophiolite boninites are likely associated with forearc/intra-arc spreading during the protracted evolution of the Cambrian arc system. The relatively young boninites in the Bronson Hill Arc suggest that the Taconic continuous eastward subduction tectonic model is less tenable than other models. On the Gondwana side of Iapetus, the

  13. A clinico-epidemiological study of epidemic typhus in Africa.

    PubMed

    Perine, P L; Chandler, B P; Krause, D K; McCardle, P; Awoke, S; Habte-Gabr, E; Wisseman, C L; McDade, J E

    1992-05-01

    Epidemic, louse-borne typhus persists in the rugged, mountainous areas of Ethiopia and much of northeastern and central Africa as well as in the rural highlands of Central and South America, where the conditions of living favor the harboring of body lice and where antibiotic treatment and effective louse-control measures are unavailable. The historical significance and current epidemiology of typhus, including the reservoir of Rickettsia prowazekii in flying squirrels in the United States, are reviewed, and the clinical presentation, laboratory findings, and hospital course in the cases of 60 patients admitted with epidemic, louse-borne typhus to the St. Paul's Hospital in Addis Ababa, Ethiopia, are described. Treatment of this disease with oral doxycycline, tetracycline, or chloramphenicol prevents complications and results in prompt resolution of symptoms. PMID:1600020

  14. Granger causality and Atlantic hurricanes

    NASA Astrophysics Data System (ADS)

    Elsner, James B.

    2007-08-01

    Atlantic tropical cyclones have been getting stronger recently with a trend that is related to an increase in the late summer/early fall sea-surface temperature over the North Atlantic. Some studies attribute the increasing ocean warmth and hurricane intensity to a natural climate fluctuation, known as the Atlantic Multidecadal Oscillation; others suggest that climate change related to anthropogenic greenhouse gases emissions is the cause. Noting that the only difference between these two hypotheses is the causal connection between global mean near-surface air temperature (GT) and Atlantic sea-surface temperature (SST), the author previously showed how to use statistical tests to examine this hypothesis. Here the author expands on this research. In particular, a more comprehensive explanation of the techniques and additional tests and checks against misspecification are provided. The earlier results are confirmed in showing that preceding GT anomalies have a significant statistical relationship to current SST anomalies but not conversely so that if causality exists between Atlantic SST and global temperature, the causal direction likely goes from GT to SST. The result is robust against a small amount of noise added to the data. Identical tests applied to surrogate time series fail to identify causality as expected. The work underscores the importance of using data models to understand relationships between hurricanes and climate.

  15. Phylogenetic analysis in Myrcia section Aulomyrcia and inferences on plant diversity in the Atlantic rainforest

    PubMed Central

    Staggemeier, Vanessa Graziele; Diniz-Filho, José Alexandre Felizola; Forest, Félix; Lucas, Eve

    2015-01-01

    Background and Aims Myrcia section Aulomyrcia includes ∼120 species that are endemic to the Neotropics and disjunctly distributed in the moist Amazon and Atlantic coastal forests of Brazil. This paper presents the first comprehensive phylogenetic study of this group and this phylogeny is used as a basis to evaluate recent classification systems and to test alternative hypotheses associated with the history of this clade. Methods Fifty-three taxa were sampled out of the 120 species currently recognized, plus 40 outgroup taxa, for one nuclear marker (ribosomal internal transcribed spacer) and four plastid markers (psbA-trnH, trnL-trnF, trnQ-rpS16 and ndhF). The relationships were reconstructed based on Bayesian and maximum likelihood analyses. Additionally, a likelihood approach, ‘geographic state speciation and extinction’, was used to estimate region- dependent rates of speciation, extinction and dispersal, comparing historically climatic stable areas (refugia) and unstable areas. Key Results Maximum likelihood and Bayesian inferences indicate that Myrcia and Marlierea are polyphyletic, and the internal groupings recovered are characterized by combinations of morphological characters. Phylogenetic relationships support a link between Amazonian and north-eastern species and between north-eastern and south-eastern species. Lower extinction rates within glacial refugia suggest that these areas were important in maintaining diversity in the Atlantic forest biodiversity hotspot. Conclusions This study provides a robust phylogenetic framework to address important ecological questions for Myrcia s.l. within an evolutionary context, and supports the need to unite taxonomically the two traditional genera Myrcia and Marlierea in an expanded Myrcia s.l. Furthermore, this study offers valuable insights into the diversification of plant species in the highly impacted Atlantic forest of South America; evidence is presented that the lowest extinction rates are found inside

  16. Latest Jurassic-early Cretaceous regressive facies, northeast Africa craton

    SciTech Connect

    van Houten, F.B.

    1980-06-01

    Nonmarine to paralic detrital deposits accumulated in six large basins between Algeria and the Arabo-Nubian shield during major regression in latest Jurassic and Early Cretaceous time. The Ghadames Sirte (north-central Libya), and Northern (Egypt) basins lay along the cratonic margin of northeastern Africa. The Murzuk, Kufra, and Southern (Egypt) basins lay in the south within the craton. Data for reconstructing distribution, facies, and thickness of relevant sequences are adequate for the three northern basins only. High detrital influx near the end of Jurassic time and in mid-Cretaceous time produced regressive nubian facies composed largely of low-sinuosity stream and fahdelta deposits. In the west and southwest the Ghadames, Murzuk, and Kufra basins were filled with a few hundred meters of detritus after long-continued earlier Mesozoic aggradation. In northern Egypt the regressive sequence succeeded earlier Mesozoic marine sedimentation; in the Sirte and Southern basins correlative deposits accumulated on Precambrian and Variscan terranes after earlier Mesozoic uplift and erosion. Waning of detrital influx into southern Tunisia and adjacent Libya in the west and into Israel in the east initiated an Albian to early Cenomanian transgression of Tethys. By late Cenomanian time it had flooded the entire cratonic margin, and spread southward into the Murzuk and Southern basins, as well as onto the Arabo-Nubian shield. Latest Jurassic-earliest Cretaceous, mid-Cretaceous, and Late Cretaceous transgressions across northeastern Africa recorded in these sequences may reflect worldwide eustatic sea-level rises. In contrast, renewed large supply of detritus during each regression and a comparable subsidence history of intracratonic and marginal basins imply regional tectonic control. 6 figures.

  17. The Inter-Tropical Convergence Zone: A causal mechanism for Pb isotope cyclicity in Tropical Atlantic sediment cores

    NASA Astrophysics Data System (ADS)

    Abouchami, W.; Zabel, M.

    2003-04-01

    Lead isotopic compositions of bulk sediment cores from the Tropical Atlantic can be used to infer variations in the provenance of terrigenous input to the Tropical Atlantic during Pleistocene climate cycles. Pb isotope data were obtained using the triple spike method (Galer, 1999) on bulk sediments cores and cover the last six Marine Isotope Stages. The 200-ka high precision (2σ ˜100 ppm) Pb isotope records of the Ceará Rise (Western Atlantic, core GeoB1523-1, 3^o49'N, 41^o37'W, 3292 m) and Sierra Leone Rise (Eastern Atlantic, core GeoB2910-1, 4^o50'N, 21^o03'W, 2703 m) cores show a clear glacial-interglacial cyclicity, reflected by alternating unradiogenic Pb and radiogenic Pb. Changes in the relative proportions of the glacial (unradiogenic) and interglacial (radiogenic) Pb source(s) can be explained by changes in the erosional regime (chemical vs. physical) as a function of prevailing climate, combined with different mechanisms of Pb transport to the oceans (predominantly eolian in the Eastern Atlantic vs. riverine in the Western Atlantic). We interpret these regional changes as reflecting shifts in the mean latitude of the Inter-Tropical Convergence Zone that affects the hydrological cycle over South America and the wind systems over Africa. Our results strongly favor an increase in winter wind transport (rather than glacial hyper aridity) as the cause of enhanced glacial terrigenous fluxes observed in the Tropical Atlantic (Ruddiman, 1997). The two Atlantic Pb isotopic records exhibit strong correlations with Pleistocene sea level fluctuations, providing evidence for global teleconnection between tropical records and high latitude climate. Galer, S.J.G. (1999). Optimal double and triple spiking for high precision lead isotopic measurements. Chem. Geol. 154, 255-274. Ruddiman, W. F. (1997). Tropical Atlantic terrigenous fluxes since 25,000 yrs B.P., Mar. Geol., 136, 189-207.

  18. Temperature mediated moose survival in Northeastern Minnesota

    USGS Publications Warehouse

    Lenarz, M.S.; Nelson, M.E.; Schrage, M.W.; Edwards, A.J.

    2009-01-01

    The earth is in the midst of a pronounced warming trend and temperatures in Minnesota, USA, as elsewhere, are projected to increase. Northern Minnesota represents the southern edge to the circumpolar distribution of moose (Alces alces), a species intolerant of heat. Moose increase their metabolic rate to regulate their core body temperature as temperatures rise. We hypothesized that moose survival rates would be a function of the frequency and magnitude that ambient temperatures exceeded the upper critical temperature of moose. We compared annual and seasonal moose survival in northeastern Minnesota between 2002 and 2008 with a temperature metric. We found that models based on January temperatures above the critical threshold were inversely correlated with subsequent survival and explained >78 of variability in spring, fall, and annual survival. Models based on late-spring temperatures also explained a high proportion of survival during the subsequent fall. A model based on warm-season temperatures was important in explaining survival during the subsequent winter. Our analyses suggest that temperatures may have a cumulative influence on survival. We expect that continuation or acceleration of current climate trends will result in decreased survival, a decrease in moose density, and ultimately, a retreat of moose northward from their current distribution.

  19. Hongshan chiefly communities in Neolithic northeastern China

    PubMed Central

    Peterson, Christian E.; Lu, Xueming; Drennan, Robert D.; Zhu, Da

    2010-01-01

    The Hongshan societies of northeastern China are among East Asia’s earliest complex societies. They have been known largely from elaborate burials with carved jades in ceremonial platforms. The most monumental remains are concentrated in a “core zone” in western Liaoning province. Residential remains are less well known and most investigations of them have been in peripheral regions outside the core zone. Recent regional settlement pattern research around the well known ceremonial site of Dongshanzui has begun to document the communities that built and used Hongshan core zone monuments and to assess their developmental dynamics. The core zone, like the Hongshan periphery, appears to have been organized into a series of small chiefly districts within which ceremonial activities were important integrative forces. Their estimated populations of less than 1,000 are not much larger than those of districts in the periphery, and the evidence does not suggest that these districts were integrated into any larger political entity. The greater elaboration of core zone monumental architecture is thus not attributable to demographically larger communities or to larger-scale political integration. Future research should focus on documenting the organization of statuses and economic activities within these core zone communities to assess potential differences from peripheral communities in these regards. PMID:20224038

  20. A palaeomagnetic reconnaissance of northeastern Baluchistan, Pakistan

    NASA Astrophysics Data System (ADS)

    Klootwijk, Chris T.; Nazirullah, Russel; de Jong, Kees A.; Ahmed, Habib

    1981-01-01

    A total of 560 samples from three areas in northeastern Baluchistan (the southern Sulaiman Range, the central Loralai Range, and the northern Kirthar Range) were analyzed using thermal demagnetization techniques. Thirteen formations of late Palaeozoic to early Tertiary age were studied palaeomagnetically. Inclinations of the obtained results show a general affinity with the Indian apparent polar wander path. Deviating declinations from the Loralai Range indicate a clockwise rotation over 50° with respect to the Indian shield. Secondary magnetization components probably of late Palaeocene to early Eocene age were consistently present in the samples from the Kirthar Range and the Sulaiman Range but were not observed in samples from the Loralai Range. Acquisition of these components is attributed to crustal upwarping during the Palaeocene, which is tentatively related to initial collision of continental Indo-Pakistan with an island arc off south central Asia. The Baluchistan data support recent palaeomagnetic results from the Indus-Tsangpo suture zone in Ladakh (NW Himalaya), which indicate that such an initial collision took place at very low northern palaeolatitudes.

  1. Filarioids infecting dogs in northeastern Brazil.

    PubMed

    Ramos, Rafael Antonio Nascimento; de Oliveira do Rêgo, Ana Gabriela; de Farias Firmino, Everton Diogo; do Nascimento Ramos, Carlos Alberto; de Carvalho, Gílcia Aparecida; Dantas-Torres, Filipe; Otranto, Domenico; Alves, Leucio Câmara

    2016-08-15

    Species of filarial nematodes belonging to the genera Dirofilaria and Acanthocheilonema are recognised as common parasites of dogs throughout the world. Recently, other filarioids featured by the presence of dermal microfilariae (e.g., Onchocerca lupi and Cercopithifilaria spp.) have been recognised in Europe. In Brazil, reports of filarioids in dogs are limited to Dirofilaria immitis, Acanthocheilonema reconditum and Cercopithifilaria bainae. To investigate the distribution of filarial infections in dogs living in an endemic region from northeastern Brazil, blood and skin samples (n=104) were microscopically (modified Knott's test and skin snip sediment examination) and molecularly evaluated. Twenty-two dogs (21.15%) were positive at microscopic and/or molecular examination for at least one filarioid species, with 21 (20.19%) animals positive for blood microfilariae at molecular and/or at microscopic examination. Microfilariae of D. immitis were detected in 12 (11.54%) animals, with co-infection of D. immitis and A. reconditum observed in four (3.85%) individuals. One animal was positive for C. bainae at both microscopic and molecular examination. Analysis of sequence obtained in the present study showed significant alignment identity with that of C. bainae from Europe. Considering that in the area of study arthropod vectors (mosquitoes, fleas and ticks) are prevalent throughout the year, preventive measures should be disposed in order to avoid the animal infestation and pathogen infection. PMID:27514878

  2. Cholera outbreaks in Africa.

    PubMed

    Mengel, Martin A; Delrieu, Isabelle; Heyerdahl, Leonard; Gessner, Bradford D

    2014-01-01

    During the current seventh cholera pandemic, Africa bore the major brunt of global disease burden. More than 40 years after its resurgence in Africa in 1970, cholera remains a grave public health problem, characterized by large disease burden, frequent outbreaks, persistent endemicity, and high CFRs, particularly in the region of the central African Great Lakes which might act as reservoirs for cholera. There, cases occur year round with a rise in incidence during the rainy season. Elsewhere in sub-Saharan Africa, cholera occurs mostly in outbreaks of varying size with a constant threat of widespread epidemics. Between 1970 and 2011, African countries reported 3,221,050 suspected cholera cases to the World Health Organization, representing 46 % of all cases reported globally. Excluding the Haitian epidemic, sub-Saharan Africa accounted for 86 % of reported cases and 99 % of deaths worldwide in 2011. The number of cholera cases is possibly much higher than what is reported to the WHO due to the variation in modalities, completeness, and case definition of national cholera data. One source on country specific incidence rates for Africa, adjusting for underreporting, estimates 1,341,080 cases and 160,930 deaths (52.6 % of 2,548,227 estimated cases and 79.6 % of 209,216 estimated deaths worldwide). Another estimates 1,411,453 cases and 53,632 deaths per year, respectively (50 % of 2,836,669 estimated cases and 58.6 % of 91,490 estimated deaths worldwide). Within Africa, half of all cases between 1970 and 2011 were notified from only seven countries: Angola, Democratic Republic of the Congo, Mozambique, Nigeria, Somalia, Tanzania, and South Africa. In contrast to a global trend of decreasing case fatality ratios (CFRs), CFRs have remained stable in Africa at approximately 2 %. Early propagation of cholera outbreaks depends largely on the extent of individual bacterial shedding, host and organism characteristics, the likelihood of people coming into contact with

  3. Compound-specific isotopic analyses track changes in seasonal precipitation regimes in the Northeastern United States at ca 8200 cal yr BP

    NASA Astrophysics Data System (ADS)

    Shuman, Bryan; Huang, Yongsong; Newby, Paige; Wang, Yi

    2006-11-01

    We analyzed the hydrogen isotopic composition of sedimentary leaf wax (C 28n-acid) and palmitic acid (C 16n-acid) in cores from Berry and Crooked Ponds in Massachusetts. The results show a dramatic positive shift in leaf wax δD values around 8200 cal yr BP, when regional lake levels rose and plant communities shifted in favor of plants intolerant of dry conditions. To aid our interpretation, we studied modern lake sediment samples and found that the δD values of leaf wax and palmitic acid record the hydrogen isotopic composition of water available during the synthesis of these compounds. Palmitic acid δD values follow lake water values often derived from winter precipitation, and leaf wax δD values track the water available to terrestrial plants during the growing season. Based on these results, we interpret the downcore isotopic shift as an increase in the fraction of precipitation falling during the growing season. The increase coincides with evidence from pollen and palmitic acid δD values for a multi-century period of cold conditions at ca 8200 cal yr BP. The close timing of the brief cool period and a step-change in summer precipitation levels in the northeastern United States is consistent with the hypothesis that the collapse of the Laurentide ice sheet occurred in association with cold North Atlantic conditions from 8400 to 8000 cal yr BP. The location of the northeastern US downwind of the ice sheet and close to the North Atlantic makes it sensitive to both factors. Our results also provide insight into later changes in the northeastern US because they indicate a progressive decrease in summer precipitation levels after ca 8000 cal yr BP.

  4. South Atlantic meridional fluxes

    NASA Astrophysics Data System (ADS)

    Garzoli, Silvia L.; Baringer, Molly O.; Dong, Shenfu; Perez, Renellys C.; Yao, Qi

    2013-01-01

    The properties of the meridional overturning circulation (MOC) and associated meridional heat transport (MHT) and salt fluxes are analyzed in the South Atlantic. The oceanographic data used for the study consist of Expendable bathythermograph (XBT) data collected along 27 sections at nominally 35°S for the period of time 2002-2011, and Argo profile data collected in the region. Previous estimates obtained with a shorter record are improved and extended, using new oceanographic sections and wind fields. Different wind products are analyzed to determine the uncertainty in the Ekman component of the MHT derived from their use. Results of the analysis provide a 9-year time series of MHT, and volume transport in the upper layer of the MOC. Salt fluxes at 35°S are estimated using a parameter introduced by numerical studies, the Mov that represents the salt flux and helps determine the basin scale salt feedback associated with the MOC. Volume and heat transport by the western and eastern boundary currents are estimated, and their covariablity is examined. Analysis of the data shows that the South Atlantic is responsible for a northward MHT with a mean value of 0.54±0.14 PW. The MHT exhibits no significant trend from 2002 to 2011. The MOC varies from 14.4 to 22.7 Sv with a mean value of 18.1±2.3 Sv and the maximum overturning transport is found at a mean depth of 1250 m. Statistical analysis suggests that an increase of 1 Sv in the MOC leads to an increase of the MHT of 0.04±0.02 PW. Estimates of the Mov from data collected from three different kinds of observations, contrary to those obtained from models, feature a positive salt advection feedback (Mov<0) suggesting that freshwater perturbations will be amplified and that the MOC is bistable. In other words, the MOC might collapse with a large enough freshwater perturbation. Observations indicate that the mean value of the Brazil Current is -8.6±4.1 Sv at 24°S and -19.4±4.3 Sv at 35°S, increasing towards the

  5. Atlantic Seaduck Project

    USGS Publications Warehouse

    Perry, M.C.

    2006-01-01

    Atlantic Seaduck Project is being conducted to learn more about the breeding and moulting areas of seaducks in northern Canada and more about their feeding ecology on wintering areas, especially Chesapeake Bay. Satellite telemetry is being used to track surf scoters wintering in Chesapeake Bay, Maryland and black scoters on migrational staging areas in New Brunswick, Canada to breeding and moulting areas in northern Canada. Various techniques used to capture the scoters included mist netting, night-lighting, and net capture guns. All captured ducks were transported to a veterinary hospital where surgery was conducted following general anaesthesia procedures. A PTT100 transmitter (39 g) manufactured by Microwave, Inc., Columbia, Maryland was implanted into the duck?s abdominal cavity with an external (percutaneous) antenna. Eight of the surf scoters from Chesapeake Bay successfully migrated to possible breeding areas in Canada and all 13 of the black scoters migrated to suspected breeding areas. Ten of the 11 black scoter males migrated to James Bay presumably for moulting. Updated information from the ARGOS Systems aboard the NOAA satellites on scoter movements was made accessible on the Patuxent Website. Habitat cover types of locations using GIS (Geographical Information Systems) and aerial photographs (in conjunction with remote sensing software) are currently being analyzed to build thematic maps with varying cosmetic layer applications. Many factors related to human population increases have been implicated in causing changes in the distribution and abundance of wintering seaducks. Analyses of the gullet (oesophagus and proventriculus) and the gizzard of seaducks are currently being conducted to determine if changes from historical data have occurred. Scoters in the Bay feed predominantly on the hooked mussel and several species of clams. The long-tailed duck appears to select the gem clam in greater amounts than other seaducks, but exhibits a diverse diet of

  6. Effects of orbital-scale ITCZ fluctuations on the mid Cretaceous tropical Atlantic region

    NASA Astrophysics Data System (ADS)

    Hofmann, P.; Beckmann, B.; Flögel, S.; Wagner, T.

    2009-04-01

    Shifts of the Inter Tropic Convergence Zone (ITCZ) on Milankovitch time scales have profound effects on the climate-ocean system of tropical regions. Changes in wind systems, regional hydrology and continental runoff linked to past fluctuations of the ITCZ are well known to have triggered a complex chain of forcing and feedback mechanisms between the regional biosphere and geosphere. In our study we explore these relationships for the mid-Cretaceous super-greenhouse. We present proxy records from two regions of the Coniacian tropical Atlantic, ODP Site 959 (West Africa off Ivory Coast) and ODP Site 1261 (Northern South America off Suriname) and compare them with results of GENESIS Atmospheric General Circulation modeling. Our data suggest that bioproductivity in the eastern tropical Atlantic mainly followed a precession controlled cyclic pattern which was closely linked to changes in nutrient and freshwater supply via continental runoff from the African continent. Different from that bioproductivity in the western tropical Atlantic shows a strong obliquity and eccentricity cycle pattern. We propose that these differences in the west were mainly caused by fluctuations in wind-driven upwelling off northern South America with a constant and high supply of nutrients from the continent maintaining the ocean redox system anoxic without interruption. Bioproductivity from wind-driven upwelling in the west would have pushed the water column into repetitive sulfidic conditions (euxinia), as confirmed by geochemical evidence. Overall bioproductivity east and west of the tropical Atlantic was high supporting deposition of extensive black shale deposits. The observed differences in depositional patterns on both sides of the Coniacian tropical Atlantic support that (orbital-driven) fluctuations of the ITCZ were mainly responsible, with strong contrasts in regional moisture distribution over Africa and South America and local strengthening of the trade wind system causing

  7. Relief evolution of Africa since 300 Ma: outcomes of the TopoAfrica project

    NASA Astrophysics Data System (ADS)

    Guillocheau, François; Braun, Jean; TopoAfrica Working Group

    2013-04-01

    The goal of this project was to quantify the growth of long wavelength (x1000 km) topography over the last 300 My at the scale of a continent - Africa - and to understand (1) their relationship with the underlying mantle dynamics over such a time period and (2) their consequence over some Earth surface processes. A direct inversion of the geological data into estimates of paleotopography is difficult. Quantification of past topographies of a continent requires coupling of geological data with a sediment production (erosion) and transport numerical model. The quantification of the Meso-Cenozoic topographies of the African continent is based on uplift (mean time interval 10 my) and paleoprecipitation maps (input of the model) and siliciclastic sedimentary fluxes and thermochronological data. • No relief, older than Late Cretaceous (75-65 Ma), are preserved in Africa. This oldest relief corresponds to part of the present-day South African Plateau. Northward, no relief is older than the Middle Eocene (50-40 Ma). • This implies that for past relief reconstruction, the geomorphological analysis is only efficient for the second half of the Cenozoic. For oldest periods, a model-based approach such as the one developed in the project is required. • The mantle dynamic cannot explain all the long wavelength relief of Africa, even during Cenozoic times. The critical point was the movement of the African plate over the African superplume, perennial since at least the Early Cretaceous (110-100 Ma): this horizontal movement controlled the uplift of the South African Plateau during Late Cretaceous times (90-75 Ma). Other mechanisms have to be involved to explain the growth of the marginal bulges of the South Atlantic margins or the double bending of the Congo Cuvette during Neogene times. • The weak point of the project is the palaeoclimate and mainly the paleoprecipitation quantifications, key information for the understanding of relief evolution. Few geological studies

  8. Climatic Variability over the North Atlantic

    NASA Astrophysics Data System (ADS)

    Hurrell, J.; Hoerling, M. P.; Folland, C. K.

    INTRODUCTION WHAT IS THE NORTH ATLANTIC OSCILLATION AND HOW DOES IT IMPACT REGIONAL - CLIMATE? WHAT ARE THE MECHANISMS THAT GOVERN NORTH ATLANTIC OSCILLATION VARIABILITY? Atmospheric Processes Ocean Forcing of the Atmosphere CONCLUDING COMMENTS ON THE OTHER ASPECTS OF NORTH ATLANTIC CLIMATE - VARIABILITY REFERENCES

  9. Atlantic opportunities for ENSO prediction

    NASA Astrophysics Data System (ADS)

    del Rey, Marta Martin; Rodríguez-Fonseca, Belén; Polo, Irene

    2015-04-01

    El Niño-Southern Oscillation (ENSO) is the dominant mode of tropical climate variability with worldwide impacts. Major advances in ENSO research have been done in the last decades, focusing on the mechanisms involved in its onset and development, as well as, its global climate teleconnections. Although modelling efforts have been made in ENSO forecast, the prediction of these episodes still remains a challenge for the scientific community. Recent studies put forward the role of extra-tropical and tropical regions as precursors of ENSO, but these teleconnections have changed along the 20th century. In particular, an Atlantic Niño precedes the development of a Pacific La Niña (and vice versa) 6 months in advance, taking part of an air-sea coupled mode of variability which only shows up during negative phases of the Atlantic Multidecadal Oscillation (AMO). The non-stationarity of this mode opens window opportunities for ENSO forecast, using the Tropical Atlantic Sea Surface Temperature (SST) as the predictor field. Here, we present for the first time a statistical crossvalidated hindcast of ENSO events based on an Extended Multiple Maximum Covariance Analysis (EMMCA). This method considers a unique predictor field, the summer Atlantic SSTs, and a set of predictant fields in different regions and seasons, according to the Atlantic-Pacific mechanism. The predicted tropical Pacific variables involved in ENSO development, show a good agreement with the observed ones during negative AMO phases, with a remarkable increase of the predictability skill based on correlations. During those negative AMO decades, the hindcast reproduces quite well the observed Atlantic-modulated ENSO episodes, but with stronger signal than observations. This AMO-dependency of the ENSO predictability could help to resolve some open questions about the seasonal to decadal ENSO forecast and its impacts.

  10. Indian - Atlantic interocean exchange: variability and controls

    NASA Astrophysics Data System (ADS)

    Schouten, Mathijs Wilhelmus

    2002-05-01

    South of Africa, warm Indian Ocean water enters the Atlantic Ocean by means of large Agulhas Rings. These rings, with diameters up to 350 km and reaching all the way to the ocean floor at 5 km depth, form an important link in the global thermohaline circulation, which is the driving force behind the moderate temperatures over Northern Europe. For six years, the shedding of Agulhas rings has been monitored from space, using satellite altimeter measurements of the sea surface height. Rings can be identified by sea surface elevations on the order of 20-50 cm. The rings are followed on their way westward through the Atlantic, where they gradually decay. The decay is found to take place mainly in the Cape Basin during the first year after formation, probably delivering most of the Ring's thermohaline contents to this region. Also, rings are observed to often split into smaller rings. The shedding of Agulhas Rings is shown to be related to upstream processes. Especially, eddies from the Mozambique Channel are found to control the timing of Agulhas Ring shedding. These Mozambique Eddies have recently been measured to be dynamically comparable to the energetic Agulhas Rings, to carry tropical water masses southward through the Mozambique Channel, and to induce strong mixing in the channel. They in turn seem to be part of a mode of variability that is found over much of the Indian Ocean. A four-per-year signal is found to originate in the equatorial part of the Indian Ocean, and to propagate by a sequence of Kelvin and Rossby waves into the Mozambique Channel. Kelvin waves at the equator are forced by the semi-annual westerly windbursts that occur during the change of the monsoons. The frequency of these waves is doubled to four, probably by resonance of an equatorial basin mode. Four Kelvin waves per year are observed to reach the Indonesian coast, where they travel southward as coastal Kelvin waves. These force baroclinic Rossby waves at subtropical latitudes, which

  11. A new species of Dolicholana Bruce, 1986 (Isopoda, Cymothoidea, Cirolanidae), the first record of the genus from the Atlantic Ocean.

    PubMed

    Paiva, Ricardo J C; Souza-Filho, Jesser F

    2015-01-01

    The isopod genus Dolicholana Bruce, 1986, previously known only from the Indo-West Pacific, is recorded for the first time from the Atlantic Ocean. A new species, Dolicholana brucei sp. nov., is described from the northeastern Brazilian coast, and is the first record of the genus Dolicholana Bruce, 1986 for the Atlantic Ocean. The material was collected from the upper part of the continental slope off Rio Grande do Norte (150 m depth). The new species is characterized by pereopod 1 propodal palm being crenulate, ischium of pereopod 1 and 2 with a plumose seta on the anterior margin, peduncle of pleopods 3-5 bearing an accessory lobe acute on the distolateral angle, pleotelson posterior margin being rounded, and the uropodal endopod and the exopod apices distally being rounded. A revised key to the genus is provided. PMID:26624479

  12. A Study of Mesoscale Gravity Waves over the North Atlantic with Satellite Observations and a Mesoscale Model

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Zhang, Fuqing

    2004-01-01

    Satellite microwave data are used to study gravity wave properties and variabilities over the northeastern United States and the North Atlantic in the December-January periods. The gravity waves in this region, found in many winters, can reach the stratopause with growing amplitude. The Advanced Microwave Sounding Unit-A (AMSU-A) observations show that the wave occurrences are correlated well with the intensity and location of the tropospheric baroclinic jet front systems. To further investigate the cause(s) and properties of the North Atlantic gravity waves, we focus on a series of wave events during 19-21 January 2003 and compare AMSU-A observations to simulations from a mesoscale model (MM5). The simulated gravity waves compare qualitatively well with the satellite observations in terms of wave structures, timing, and overall morphology. Excitation mechanisms of these large-amplitude waves in the troposphere are complex and subject to further investigations.

  13. Cenozoic siliciclastic sediment budget at continent-scale, Africa.

    NASA Astrophysics Data System (ADS)

    Guillocheau, François; Robin, Cécile; Calves, Gérôme; Baby, Guillaume

    2013-04-01

    Siliciclastic sediment budget measurements was performed along the margins and onshore basins of Africa for Cenozoic times. Our objective was first to quantify the ratio between onshore and offshore sediment preservation in the case of a relief with mostly no mountain belt and secondly to understand the factors forcing the sediment supply along the passive margins of Africa that can be long to very-long relief deformation (mantle dynamics, ridge push…) or climate changes (with the major aridification of Africa since Middle Miocene). This study is based on basin-scale regional sections (seismic reflection data from industry and academics, wells correlation), calibrated in age and lithology on different types of wells (industry, DSDP/ODP). Most of the effort was on the revaluation of the ages (calibration and uncertainties). The volumes of sediments and uncertainties on depth conversion velocity laws, lithology and ages were measured using software developed by J. Braun (Grenoble University, France). • The sediment preserved onshore (750 000 km3) is one of magnitude less than was is preserved offshore • The main deformations controlling the sediment supply are (1) the growth or the domes of the East African rift and (2) the marginal bulge of the central and equatorial segments of the South Atlantic Ocean (from southern Angola to Guinea). • The aridification of Africa since at least Middle Miocene is very sensitive in the south (fossilization of the relief of the South African Plateau) and in the northwest, with a sharp decrease of the sediment supply. • Some buffer effects are very important, for example for the Nile and the Zambezi, where sediments were first stored in onshore basins, Sudan or Malawi rift, and later drained because of a capture (Nile) or a regional stress change (Zambezi). Keywords: Africa, Cenozoic, Siliciclastic sediment fluxes, Deformation, Climate

  14. Internet Performance to Africa

    SciTech Connect

    Cottrell, L

    2003-10-01

    We report the first results ever for real-time Internet performance to Africa using the PingER methodology. Multiple monitoring hosts were used to enable comparisons with performance from different parts of the world. From these preliminary measurements, we have found that Internet packet losses to some African sites in recent months range from very poor to bad (> 12%), some getting better, others are holding steady or getting worse. This, together with the average monthly Round Trip Times, imply end-to-end maximum TCP throughputs that are order of magnitudes different between countries in the region. Africa is shown to be far from the Internet performance in industrialized nations due to the poor infrastructure in place today. These monitoring efforts can provide valuable information to analyze the relative rates of future improvement and today they help us to quantify the digital divide and can provide quantitative information to policy makers.

  15. Tuberculosis in tropical Africa

    PubMed Central

    Roelsgaard, E.; Iversen, E.; Bløcher, C.

    1964-01-01

    Up to the end of the nineteenth century the tubercle bacillus apparently had little opportunity of disseminating among the rather isolated tribes of tropical Africa. With the creation of large centres of trade and industry in the wake of European colonization, tuberculosis seems to have spread rapidly over the continent and is today found everywhere. In a number of tuberculosis prevalence surveys conducted by WHO during 1955-60, randomly selected population groups were tuberculin tested, X-rayed and had sputa examined by direct microscopy. The three methods of examination were applied independently of one another. Data collected during the surveys have been analysed with a view to discovering common epidemiological features of tuberculosis in tropical Africa, assessing the reliability of the diagnostic methods employed and discussing their usefulness in future tuberculosis control programmes. PMID:14178027

  16. This Is Africa.

    PubMed

    Verlo, April R; Bailey, Hugh H; Cook, Martin R

    2015-01-01

    Military deployments will always result in exposure to health hazards other than those from combat operations. The occupational and environmental health and endemic disease health risks are greater to the Special Operations Forces (SOF) deployed to the challenging conditions in Africa than elsewhere in the world. SOF are deployed to locations that lack life support infrastructures that have become standard for most military deployments; instead, they rely on local resources to sustain operations. Particularly, SOF in Africa do not generally have access to advanced diagnostic or monitoring capabilities or to medical treatment in austere locations that lack environmental or public health regulation. The keys to managing potential adverse health effects lie in identifying and documenting the health hazards and exposures, characterizing the associated risks, and communicating the risks to commanders, deployed personnel, and operational planners. PMID:26360366

  17. Potential environmental contaminant risks to avian species at important bird areas in the northeastern United States

    USGS Publications Warehouse

    Rattner, B.A.; Ackerson, B.K.

    2008-01-01

    Environmental contaminants can have profound effects on birds, acting from the molecular through population levels of biological organization. An analysis of potential contaminant threats was undertaken at 52 Important Bird Areas (IBAs) within the northeastern Atlantic coast drainage. Using geographic information system methodology, data layers describing or integrating contamination (impaired waters, fish or wildlife consumption advisories, toxic release inventory sites, and estimates of pesticide use) were overlaid on buffered IBA boundaries, and the relative threat at each site was ranked. The most threatened sites include Jefferson National Forest (NF), Stewart B. McKinney National Wildlife Refuge (NWR), Great Dismal Swamp NWR, Blue Ridge Parkway, Shenandoah National Park (NP), Adirondack Park, Edwin B. Forsythe NWR, George Washington NF, Green Mountain NF, Long Island Piping Plover Beaches, and Merrymeeting Bay. These sites exhibited moderate to high percentages of impaired waters and had fish consumption advisories related to mercury and polychlorinated biphenyls, and were located in counties with substantial pesticide use. Endangered, threatened and Watch List bird species are present at these sites. The Contaminant Exposure and Effects--Terrestrial Vertebrates database was searched within buffered IBA boundaries, and for a moderate number of sites there was concordance between the perceived risk and contaminant exposure. Several of the IBAs with apparently substantial contaminant threats had no avian ecotoxicological data (e.g., George Washington NF, Shenandoah NP). Based upon this screening level risk assessment, contaminant biomonitoring is warranted at such sites, and data generated from these efforts should foster natural resource management activities.

  18. Late Holocene northeastern Morocco hydroclimate reconstruction revealed from speleothems d18O record

    NASA Astrophysics Data System (ADS)

    Sifeddine, A.; Bouchaou, L., Sr.; Cruz, F. W., Sr.; Apaéstegui, J. E.; Moquet, J. S., Jr.; Strikis, N. M.; Guyot, J. L., Sr.; Cheng, H.; Auler, A. S.; Beraaouz, E. H., Sr.

    2014-12-01

    Two well dated oxygen isotope (d18O) records of speleothems collected in Chaara cave located in the Northeastern Morocco are used to investigate variations in hydroclimate conditions during the last 2000 years. The results shown in this work confirm the previous works of the North Atlantic Oscillation (NAO) reconstruction during the last millennium and bring new implications concerning its evolution extending the MCA. Our (d18O) results characterized by positive values during the Medieval Warm Period (MWP) and more negative ones during the Little Ice Ages (LIA) are in agreement with those published by Trouet et al., 2009 and Wassenburg et al., 2013. They confirm that the both periods were dominated by persistent NAO+ and NAO-conditions respectively. In addition; they highlight new evidence of the NAO evolution to beyond the last 1000 years. NAO+ conditions recorded during the MCA persist until 500 AD and NAO- conditions dominate the Dark cold Period (DACP) as recorded during the LIA. Finally, the Current Warm Period (CWP) was marked by a clear change in isotope variations linked to decreased precipitation controlled by intensification in NAO + conditions.

  19. Variations in productivity and eolian fluxes in the northeastern Arabian Sea during the past 110 ka

    NASA Astrophysics Data System (ADS)

    Pourmand, Ali; Marcantonio, Franco; Schulz, Hartmut

    2004-04-01

    High-resolution (one to two samples/ka) radionuclide proxy records from core 93KL in the northeastern Arabian Sea provide evidence for millennial climate variability over the past 110 ka. We interpret 230Th-normalized 232Th fluxes as a proxy for eolian input, and authigenic uranium concentrations as a proxy for past productivity. We attribute orbital and suborbital variations in both proxies to changes in the intensity of the southwest Indian Ocean monsoon. The highest 230Th-normalized 232Th fluxes occur at times that are consistent with the timing of the Younger Dryas, Heinrich events 1-7 and cold Dansgaard-Oeschger stadial events recorded in the GISP2 ice core. Such high dust fluxes may be due to a weakened southwest monsoon in conjunction with strengthened northwesterlies from the Arabian Peninsula and Mesopotamia. Authigenic uranium concentrations, on the other hand, are highest during warm Dansgaard-Oeschger interstadials when the southwest monsoon is intensified relative to the northwesterly winds. Our results also indicate that on orbital timescales maximum average eolian fluxes coincide with the timing of marine isotopic stage (MIS) 2 and 4, while minimum fluxes occur during MIS 1, 3 and 5. Although the forcing mechanism(s) controlling suborbital variabilities in monsoonal intensity is still debated, our findings suggest an atmospheric teleconnection between the low-latitude southwest monsoon and North Atlantic climate.

  20. Long-term subsidence, cooling, and exhumation history along the South Atlantic passive continental margin in NW-Namibia

    NASA Astrophysics Data System (ADS)

    Menges, Daniel; Glasmacher, Ulrich Anton; Salomon, Eric; Hackspacher, Peter Christian; Schneider, Gabi

    2016-04-01

    has been estimated to ~ 2.7 km in the northeastern and ~ 4 km in the western Kaoko Belt. References 1. Miller, R.McG. Becker, T., 2008. The Geology of Namibia: Ministry of Mines and Energy, Geological Survey (Namibia). 2. Stollhofen, H., 1999. Karoo Synrift-Sedimentation und ihre tektonische Kontrolle am entstehenden Kontinentalrand Namibias: Z.dt.geol.Ges. 149: 519-632. 3. Renne, P.R., Glen, J.M., Milner, S.C., Duncan, A.R., 1996. Age of Etendeka flood volcanism and associated intrusions in southwestern Africa: Geology 24 (7): 659- 662. 4. Salomon, E., Koehn, D., Passchier, C., 2014. Brittle reactivation of ductile shear zones in NW Namibia in relation to South Atlantic rifting: Tectonics 34, 70-85.

  1. Geomagnetic observations on tristan da cunha, south atlantic ocean

    USGS Publications Warehouse

    Matzka, J.; Olsen, N.; Maule, C.F.; Pedersen, L.W.; Berarducci, A.M.; Macmillan, S.

    2009-01-01

    Few geomagnetic ground observations exist of the Earth's strongest core field anomaly, the South Atlantic Anomaly (SAA). The geomagnetic repeat station on the island Tristan da Cunha, located half-way between South Africa and South America at 37?? 05' S, 12?? 18' W, is therefore of crucial importance. We have conducted several sets of repeat station measurements during magnetically quiet conditions (Kp 2o or less) in 2004. The procedures are described and the results are compared to those from earlier campaigns and to the predictions of various global field models. Features of the local crustal bias field and the solar quiet daily variation are discussed. We also evaluate the benefit of continuous magnetic field recordings from Tristan da Cunha, and argue that such a data set is a very valuable addition to geomagnetic satellite data. Recently, funds were set up to establish and operate a magnetometer station on Tristan da Cunha during the Swarm magnetic satellite mission (2011-2014).

  2. Mozambique Coast, Africa

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The serene coastline of Mozambique (17.0S, 39.5E) Africa and the Indian Ocean offer some of the best beaches and recreational diving water in the world. Offshore reefs provide interesting coral formations that host a wide variety of marine life. Inland, the coastal savannas of this tropical nation are filled with a wide range of wildlife in some of the last animal refuges on the African continent.

  3. Lake Chad, Chad, Africa

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The fluctuating water levels of Lake Chad, (13.0N, 15.0E) at the intersection of the borders of Chad, Niger and Cameroon in the Sahara Desert, is an index of the drought in Africa. The lake level continues to decrease as indicated by the growing number and extent of emerging islands as previously submerged ancient sand dunes become visible. The water impounded between the dunes is probably because of local rainfall rather than a reversal of desertification.

  4. Drought in West Africa

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Drought settled over West Africa's Ivory Coast region when wet season rains came late in 2007. Instead of beginning in February, the rainy season didn't start until March, and steady rains didn't start until late March, said the Famine Early Warning System Network. Though the rain had started to alleviate the drought, vegetation was still depressed in parts of Cote d'Ivoire (Ivory Coast) between March 22 and April 6, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured the data used to make this image. The image shows current vegetation conditions compared to average conditions recorded since 2000. Areas where plants are growing more slowly or more sparsely than average are brown, while areas where vegetation is denser than average are green. The brown tint that dominates the image indicates that plants through most of the country are more sparse than normal. Among the crops affected by the lack of rain was West Africa's cocoa crop. About 70 percent of the world's cocoa comes from West Africa, and Cote d'Ivoire is a top grower, said Reuters. Cocoa prices climbed as the crop fell short. Farmers called the drought the worst in living memory, Reuters said. The delay in rainfall also led to water shortages in parts of Cote d'Ivoire, according to the United Nations Office for the Coordination of Humanitarian Affairs.

  5. Astrophysics in Southern Africa

    NASA Astrophysics Data System (ADS)

    Whitelock, Patricia

    2008-03-01

    The government of South Africa has identified astronomy as a field in which their country has a strategic advantage and is consequently investing very significantly in astronomical infrastructure. South Africa now operates a 10-m class optical telescope, the Southern African Large Telescope (SALT), and is one of two countries short listed to host the Square Kilometre Array (SKA), an ambitious international project to construct a radio telescope with a sensitivity one hundred times that of any existing telescope. The challenge now is to produce an indigenous community of users for these facilities, particularly from among the black population which was severely disadvantaged under the apartheid regime. In this paper I briefly describe the observing facilities in Southern Africa before going on to discuss the various collaborations that are allowing us to use astronomy as a tool for development, and at the same time to train a new generation of astronomers who will be well grounded in the science and linked to their colleagues internationally.

  6. Astronomy Across Africa

    NASA Astrophysics Data System (ADS)

    Williams, Ted

    2014-01-01

    African astronomy is growing rapidly. The Southern African Large Telescope is the largest optical telescope in the southern hemisphere, MeerKat and the Square Kilometer Array will revolutionize radio astronomy in the coming decade, and Namibia hosts HESS II, the world’s largest gamma-ray telescope. A growing community of observational and theoretical astronomers utilizes these multi-wavelength observational facilities. The largest concentrations of researchers are in southern Africa, but the community is now expanding across the continent. Substantial resources are being invested in developing the next generation of African astronomers. The African Astronomical Society was formed in 2011 to foster and coordinate the growth of the science in Africa. The IAU has located its global Office of Astronomy for Development in South Africa, with the mandate to find innovative ways of using astronomy to promote social and educational development around the world. African astronomy offers abundant opportunities for collaborative research with colleagues from across the globe. This special session will introduce many of the aspects of African astronomy to the US community, with the aim of engendering new partnerships and strengthening existing ones.

  7. Secondary Teaching Strategies on South Africa.

    ERIC Educational Resources Information Center

    Maxey, Phyllis F.

    1987-01-01

    Offers learning activities on South Africa, which help students gain background information on South Africa's culture, history, and geography; examine United States foreign policy toward South Africa; conduct community research on United States involvement with South Africa; confront different life styles of individuals living in South Africa; and…

  8. Model Sensitivity to North Atlantic Freshwater Forcing at 8.2 Ka

    NASA Technical Reports Server (NTRS)

    Morrill, Carrie; Legrande, Allegra Nicole; Renssen, H.; Bakker, P.; Otto-Bliesner, B. L.

    2013-01-01

    We compared four simulations of the 8.2 ka event to assess climate model sensitivity and skill in responding to North Atlantic freshwater perturbations. All of the simulations used the same freshwater forcing, 2.5 Sv for one year, applied to either the Hudson Bay (northeastern Canada) or Labrador Sea (between Canada's Labrador coast and Greenland). This freshwater pulse induced a decadal-mean slowdown of 10-25%in the Atlantic Meridional Overturning Circulation (AMOC) of the models and caused a large-scale pattern of climate anomalies that matched proxy evidence for cooling in the Northern Hemisphere and a southward shift of the Intertropical Convergence Zone. The multi-model ensemble generated temperature anomalies that were just half as large as those from quantitative proxy reconstructions, however. Also, the duration of AMOC and climate anomalies in three of the simulations was only several decades, significantly shorter than the duration of approx.150 yr in the paleoclimate record. Possible reasons for these discrepancies include incorrect representation of the early Holocene climate and ocean state in the North Atlantic and uncertainties in the freshwater forcing estimates.

  9. Model sensitivity to North Atlantic freshwater forcing at 8.2 ka

    NASA Astrophysics Data System (ADS)

    Morrill, C.; LeGrande, A. N.; Renssen, H.; Bakker, P.; Otto-Bliesner, B. L.

    2013-04-01

    We compared four simulations of the 8.2 ka event to assess climate model sensitivity and skill in responding to North Atlantic freshwater perturbations. All of the simulations used the same freshwater forcing, 2.5 Sv for one year, applied to either the Hudson Bay (northeastern Canada) or Labrador Sea (between Canada's Labrador coast and Greenland). This freshwater pulse induced a decadal-mean slowdown of 10-25% in the Atlantic Meridional Overturning Circulation (AMOC) of the models and caused a large-scale pattern of climate anomalies that matched proxy evidence for cooling in the Northern Hemisphere and a southward shift of the Intertropical Convergence Zone. The multi-model ensemble generated temperature anomalies that were just half as large as those from quantitative proxy reconstructions, however. Also, the duration of AMOC and climate anomalies in three of the simulations was only several decades, significantly shorter than the duration of ~150 yr in the paleoclimate record. Possible reasons for these discrepancies include incorrect representation of the early Holocene climate and ocean state in the North Atlantic and uncertainties in the freshwater forcing estimates.

  10. Downscaling GISS ModelE Boreal Summer Climate over Africa

    NASA Technical Reports Server (NTRS)

    Druyan, Leonard M.; Fulakeza, Matthew

    2015-01-01

    The study examines the perceived added value of downscaling atmosphere-ocean global climate model simulations over Africa and adjacent oceans by a nested regional climate model. NASA/Goddard Institute for Space Studies (GISS) coupled ModelE simulations for June- September 1998-2002 are used to form lateral boundary conditions for synchronous simulations by the GISS RM3 regional climate model. The ModelE computational grid spacing is 2deg latitude by 2.5deg longitude and the RM3 grid spacing is 0.44deg. ModelE precipitation climatology for June-September 1998-2002 is shown to be a good proxy for 30-year means so results based on the 5-year sample are presumed to be generally representative. Comparison with observational evidence shows several discrepancies in ModelE configuration of the boreal summer inter-tropical convergence zone (ITCZ). One glaring shortcoming is that ModelE simulations do not advance the West African rain band northward during the summer to represent monsoon precipitation onset over the Sahel. Results for 1998-2002 show that onset simulation is an important added value produced by downscaling with RM3. ModelE Eastern South Atlantic Ocean computed sea-surface temperatures (SST) are some 4 K warmer than reanalysis, contributing to large positive biases in overlying surface air temperatures (Tsfc). ModelE Tsfc are also too warm over most of Africa. RM3 downscaling somewhat mitigates the magnitude of Tsfc biases over the African continent, it eliminates the ModelE double ITCZ over the Atlantic and it produces more realistic orographic precipitation maxima. Parallel ModelE and RM3 simulations with observed SST forcing (in place of the predicted ocean) lower Tsfc errors but have mixed impacts on circulation and precipitation biases. Downscaling improvements of the meridional movement of the rain band over West Africa and the configuration of orographic precipitation maxima are realized irrespective of the SST biases.

  11. Denitrification in marine shales in northeastern Colorado

    USGS Publications Warehouse

    McMahon, P.B.; Böhlke, J.K.; Bruce, B.W.

    1999-01-01

    Parts of the South Platte River alluvial aquifer in northeastern Colorado are underlain by the Pierre Shale, a marine deposit of Late Cretaceous age that is <1000 m thick. Ground water in the aquifer is contaminated with NO3/-, and the shale contains abundant potential electron donors for denitrification in the forms of organic carbon and sulfide minerals. Nested piezometers were sampled, pore water was squeezed from cores of shale, and an injection test was conducted to determine if denitrification in the shale was a sink for alluvial NO3/- and to measure denitrification rates in the shale. Measured values of NO3/-, N2, NH4/+, ??15[NO3/-], ??15N[N2], and ??15N[NH4/+] in the alluvial and shale pore water indicated that denitrification in the shale was a sink for alluvial NO3/-. Chemical gradients, reaction rate constants, and hydraulic head data indicated that denitrification in the shale was limited by the slow rate of NO3/- transport (possibly by diffusion) into the shale. The apparent in situ first-order rate constant for denitrification in the shale based on diffusion calculations was of the order of 0.04-0.4 yr-1, whereas the potential rate constant in the shale based on injection tests was of the order of 60 yr-1. Chemical data and mass balance calculations indicate that organic carbon was the primary electron donor for denitrification in the shale during the injection test, and ferrous iron was a minor electron donor in the process. Flux calculations for the conditions encountered at the site indicate that denitrification in the shale could remove only a small fraction of the annual agricultural NO3/- input to the alluvial aquifer. However, the relatively large potential first-order rate constant for denitrification in the shale indicated that the percentage of NO3/- uptake by the shale could be considerably larger in areas where NO3/- is transported more rapidly into the shale by advection.

  12. Nitrogen Gas Fluxes in Northeastern Temperate Forests

    NASA Astrophysics Data System (ADS)

    Lafave, S.; Groffman, P. M.; Venterea, R. T.; Lovett, G. M.

    2002-12-01

    Nitrogen gas fluxes are a poorly quantified component of the nitrogen (N) cycle of forest ecosystems and are important to water quality, atmospheric chemistry and forest health. We measured fluxes of nitric oxide (NO), nitrous oxide (N2O) and dinitrogen (N2) in oak and maple stands in the Catskill mountains of New York State. Fluxes of NO and N2O were measured using in situ chambers and N2 flux was measured in intact cores incubated in a helium-oxygen atmosphere closed recirculation system in the laboratory. Fluxes of NO and N2O were higher in maple than in oak stands, which is consistent with previous work showing higher rates of N cycling under maple than oak. NO fluxes averaged 1.7 mg N m-2 d-1 in maple and 0.2 in oak. N2O fluxes averaged 0.10 mg N m-2 d-1 in maple and 0.004 in oak. However, N2 fluxes were higher in oak (2.3 mg N m-2 d-1) than maple (0.15), a surprising result that was supported by independent measurements of denitrification potential. There was marked variability in fluxes between replicate plots that was linked to the presence of understory vegetation and physical characteristics of the forest floor. Results suggest that N gas fluxes in northeastern temperate forests may be more important than previously thought and may be an important regulator of export of N to coastal waters, N-related atmospheric chemistry and forest N saturation.

  13. Constraining South Atlantic growth with seafloor spreading data

    NASA Astrophysics Data System (ADS)

    Pérez-Díaz, Lucía.; Eagles, Graeme

    2014-09-01

    Recent models of South Atlantic opening history focus on early plate divergence by incorporating intracontinental deformation, which is poorly constrained. Aiming to avoid the uncertainties in this approach, we model the entire divergence history with a joint inversion for seafloor spreading data. For this history, the pre-Campanian motion parameters are the first to feature formal uncertainty estimates. We date the onset of spreading at 138 Ma, with movement along intracontinental accommodation zones leading to the assembly of South America by 123 Ma and Africa by 106 Ma. Part of the ridge in the Agulhas Basin jumped westward soon afterward toward the Bouvet plume, initiating the motion of a short-lived Malvinas Plate. The NE Georgia and Maud rises and Agulhas Plateau formed as a large igneous province over the plume. Farther north, part of the ridge jumped eastward toward the Tristan plume around 94-93 Ma but seems not to have resulted in independent plate motion. Our results show that the South Atlantic grew by diachronous breakup of continents on just two plates. Cretaceous intracontinental deformation in South America and Africa can be interpreted in terms of the accommodation of stress associated with northward propagation of this process. The pattern of accommodation is usually envisaged as focusing all of the strain in narrow belts. With our rotations, a commonly used set of such belts accounts instead for just 42-67% of the implied total strain. We suggest that the remainder was accommodated at all scales within the continental interiors and the extended continental margins.

  14. Long Distance Dispersal and Connectivity in Amphi-Atlantic Corals at Regional and Basin Scales

    PubMed Central

    Nunes, Flavia L. D.; Norris, Richard D.; Knowlton, Nancy

    2011-01-01

    Among Atlantic scleractinian corals, species diversity is highest in the Caribbean, but low diversity and high endemism are observed in various peripheral populations in central and eastern Atlantic islands and along the coasts of Brazil and West Africa. The degree of connectivity between these distantly separated populations is of interest because it provides insight into processes at both evolutionary and ecological time scales, such as speciation, recruitment dynamics and the persistence of coral populations. To assess connectivity in broadly distributed coral species of the Atlantic, DNA sequence data from two nuclear markers were obtained for six coral species spanning their distributional ranges. At basin-wide scales, significant differentiation was generally observed among populations in the Caribbean, Brazil and West Africa. Concordance of patterns in connectivity among co-distributed taxa indicates that extrinsic barriers, such as the Amazon freshwater plume or long stretches of open ocean, restrict dispersal of coral larvae from region to region. Within regions, dispersal ability appears to be influenced by aspects of reproduction and life history. Two broadcasting species, Siderastrea siderea and Montastraea cavernosa, were able to maintain gene flow among populations separated by as much as 1,200 km along the coast of Brazil. In contrast, brooding species, such as Favia gravida and Siderastrea radians, had more restricted gene flow along the Brazilian coast. PMID:21799816

  15. The strong association between western Sahelian monsoon rainfall and intense atlantic hurricanes

    SciTech Connect

    Landsea, C.W.; Gray, W.M. )

    1992-05-01

    Seasonal variability of Atlantic basin tropical cyclones is examined with respect to the monsoon rainfall over West Africa. Variations of intense hurricanes are of the most interest, as they are responsible for over three-quarters of United States tropical cyclone spawned destruction, though they account for only one-fifth of all landfalling cyclones. Intense hurricanes have also shown a strong downward trend during the last few decades. It is these storms that show the largest concurrent association with Africa's western Sahelian June-September rainfall for the years 1949-90. Though the Sahel is currently experiencing a multidecadal drought, the relationship between Atlantic tropical cyclones and western Sahelian rainfall is not dependent on the similar downward trends in both datasets. A detrended analysis confirms that a strong association still exists, though reduced somewhat in variance explained. Additionally, independent data from the years 1899 to 1948 substantiate the existence of the tropical cyclone-western Sahelian rainfall association. The fact that the Sahel periodically experiences multidecadal wet and dry regimes suggests that the current Sahelian drought, which began in the late 1960s, could be a temporary condition that may end in the near future. When this occurs, the Atlantic hurricane basin-especially the Caribbean islands and the United States East Coast-will likely see a large increase in intense hurricane activity associated with abundant Sahelian rainfall similar to the period of the late 1940s through the 1960s.

  16. Tracking leatherback turtles from the world's largest rookery: assessing threats across the South Atlantic

    PubMed Central

    Witt, Matthew J.; Augowet Bonguno, Eric; Broderick, Annette C.; Coyne, Michael S.; Formia, Angela; Gibudi, Alain; Mounguengui Mounguengui, Gil Avery; Moussounda, Carine; NSafou, Monique; Nougessono, Solange; Parnell, Richard J.; Sounguet, Guy-Philippe; Verhage, Sebastian; Godley, Brendan J.

    2011-01-01

    Despite extensive work carried out on leatherback turtles (Dermochelys coriacea) in the North Atlantic and Indo-Pacific, very little is known of the at-sea distribution of this species in the South Atlantic, where the world's largest population nests in Gabon (central Africa). This paucity of data is of marked concern given the pace of industrialization in fisheries with demonstrable marine turtle bycatch in African/Latin American waters. We tracked the movements of 25 adult female leatherback turtles obtaining a range of fundamental and applied insights, including indications for methodological advancement. Individuals could be assigned to one of three dispersal strategies, moving to (i) habitats of the equatorial Atlantic, (ii) temperate habitats off South America or (iii) temperate habitats off southern Africa. While occupying regions with high surface chlorophyll concentrations, these strategies exposed turtles to some of the world's highest levels of longline fishing effort, in addition to areas with coastal gillnet fisheries. Satellite tracking highlighted that at least 11 nations should be involved in the conservation of this species in addition to those with distant fishing fleets. The majority of tracking days were, however, spent in the high seas, where effective implementation of conservation efforts is complex to achieve. PMID:21208949

  17. Three climate cycles of millennial-scale vegetation change in Africa (Invited)

    NASA Astrophysics Data System (ADS)

    Dupont, L. M.

    2010-12-01

    Marine sediments can deliver long well-dated continuous sequences of environmental change, not only of the ocean but also of the continents. Vegetation records from these archives are often the only land-cover records to encompass several climate cycles. Comparing vegetation development during several cycles uncovers the structural and systematic differences between glacial and interglacial vegetation. Such data may help with the validation of the current earth system models including dynamic vegetation modules. A number of marine pollen records from the East Atlantic (ODP658, GIK16415, GIK16776, GIK16867, GeoB1016) and a new one from the Indian Ocean (MD96-2048) register the vegetation development in West and South Africa over a period of more than 300 thousand years covering at least three full glacial-interglacial cycles. From these dataset typical patterns of vegetation change in Africa are inferred and differences between cycles are discussed. Both latitudinal and altitudinal shifts in the vegetation have been recorded by pollen of e.g. Chenopods, Asteraceae (daisies), Ericaceae (heath), Podocarpus (yellow wood), Poaceae (grass), and lowland forest. While latitudinal shifts in the area of desert and savannah are typical in West Africa, altitudinal changes of the belt with mountainous forest and mountainous shrubs are more common in Southern Africa. During glacial times, vegetation includes ericaceous shrubs in Southern Africa, while desert shrubs expand in West Africa, and the area of the lowland forests is strongly reduced on the whole continent.

  18. Oxygen and hydrogen isotope signatures of Northeast Atlantic water masses

    NASA Astrophysics Data System (ADS)

    Voelker, Antje H. L.; Colman, Albert; Olack, Gerard; Waniek, Joanna J.; Hodell, David

    2015-06-01

    Only a few studies have examined the variation of oxygen and hydrogen isotopes of seawater in NE Atlantic water masses, and data are especially sparse for intermediate and deep-water masses. The current study greatly expands this record with 527 δ18O values from 47 stations located throughout the mid- to low-latitude NE Atlantic. In addition, δD was analyzed in the 192 samples collected along the GEOTRACES North Atlantic Transect GA03 (GA03_e=KN199-4) and the 115 Iberia-Forams cruise samples from the western and southern Iberian margin. An intercomparison study between the two stable isotope measurement techniques (cavity ring-down laser spectroscopy and magnetic-sector isotope ratio mass spectrometry) used to analyze GA03_e samples reveals relatively good agreement for both hydrogen and oxygen isotope ratios. The surface (0-100 m) and central (100-500 m) water isotope data show the typical, evaporation related trend of increasing values equatorward with the exception for the zonal transect off Cape Blanc, NW Africa. Off Cape Blanc, surface water isotope signatures are modified by the upwelling of fresher Antarctic Intermediate Water (AAIW) that generally has isotopic values of 0.0 to 0.5‰ for δ18O and 0 to 2‰ for δD. Along the Iberian margin the Mediterranean Outflow Water (MOW) is clearly distinguished by its high δ18O (0.5-1.1‰) and δD (3-6‰) values that can be traced into the open Atlantic. Isotopic values in the NE Atlantic Deep Water (NEADW) are relatively low (δ18O: -0.1 to 0.5‰; δD: -1 to 4‰) and show a broader range than observed previously in the northern and southern convection areas. The NEADW is best observed at GA03_e Stations 5 and 7 in the central NE Atlantic basin. Antarctic Bottom Water isotope values are relatively high indicating modification of the original Antarctic source water along the flow path. The reconstructed δ18O-salinity relationship for the complete data set has a slope of 0.51, i.e., slightly steeper than the 0

  19. Identification of widespread pollution in the southern hemisphere deduced from satellite analyses. [AFRICA

    SciTech Connect

    Fishman, J. ); Fakhruzzaman, K. ); Cros, B.; Nganga, D. )

    1991-06-21

    Vertical profiles of ozone obtained from ozonesondes in Brazzaville, Congo (4{degree}S, 15{degree}E), and Ascension Island (98{degree}S, 15{degree}W) show that large quantities of tropospheric ozone are present over southern Africa and the adjacent eastern tropical South Atlantic Ocean. The origin of this pollution is widespread biomass burning in Africa. These measurements support satellite-derived tropospheric ozone data that demonstrate that ozone originating from the region is transported throughout most of the Southern Hemisphere. Seasonally high levels of carbon monoxide and methane observed at middle- and high-latitude stations in Africa, Australia, and Antarctica likely reflect the effects of this distant biomass burning. These data suggest that even the most remote regions on this planet may be significantly more polluted than previously believed.

  20. Large-scale circulation patterns associated with high concentrations of tropospheric ozone in the tropical South Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    Fakhruzzaman, K. M.; Fishman, J.; Brackett, V. G.; Kendall, J. D.; Justice, C. O.

    1994-01-01

    Several years of satellite observations indicate the presence of enhanced amounts of tropospheric ozone over the tropical South Atlantic during the austral springs. Wide-spread biomass burning is prevalent over Africa and South America during the same time of the year. Another recent satellite technique has identified the locations of fires over the continents. In this study, we present an analysis of the prevailing meteorological conditions when the highest amounts of tropospheric ozone are present.

  1. Differential opening of the Central and South Atlantic Oceans and the opening of the West African rift system

    NASA Astrophysics Data System (ADS)

    Fairhead, J. D.; Binks, R. M.

    1991-02-01

    Plate tectonic studies of the development of the Central and South Atlantic Oceans using Seasat and Geosat altimeter and magnetic anomaly isochron data now provide quantitative models of seafloor spreading through time. Such models enable an initial assessment of the differential opening between these two oceanic basins to be determined. The Equatorial Atlantic is an integral part of this oceanic rifting process, allowing stresses arising from the differential opening to be dissipated into both the Caribbean and Africa along its northern and southern boundaries respectively. The tectonic model for the West African rift system, based on geological and geophysical studies, shows a series of strike-slip fault zones diverging into Africa from the Gulf of Guinea and dissipating their shear movement into the development of extensional basins orientated perpendicular to these faults zones. The development of the West African rift system was contemporaneous with the early opening of the South Atlantic, continued to develop well after the final breakup of South America from Africa and did not cease until the late Cretaceous when there was a major phase of basin inversion and deformation. Santonian ( ~ 80 Ma) deformation across the Benue Trough (Nigeria) is broadly contemporaneous with dextral shear reactivation of the central African fracture system which, in turn resulted in renewed extension in the Sudan basins during the late Cretaceous and early Tertiary. This paper illustrates the close linkage in both time and space between the history of the African rift basins and the opening of the Atlantic. Both exhibit distinct phases of evolution with the rift basins developing in direct response to the differential opening between the Central and South Atlantic in order to dissipate stresses generated by this opening. The Mesozoic tectonic model proposed is therefore one of an intimate interaction between oceanic and continental tectonics.

  2. Long-term trends in aerosol and precipitation composition over the western North Atlantic Ocean at Bermuda

    NASA Astrophysics Data System (ADS)

    Keene, W. C.; Moody, J. L.; Galloway, J. N.; Prospero, J. M.; Cooper, O. R.; Eckhardt, S.; Maben, J. R.

    2014-03-01

    Since the 1980s, emissions of SO2 and NOx (NO + NO2) from anthropogenic sources in the United States (US) and Europe have decreased significantly suggesting that the export of oxidized S and N compounds from surrounding continents to the atmosphere overlying North Atlantic Ocean (NAO) has also decreased. The chemical compositions of aerosols and precipitation sampled daily on Bermuda (32.27° N, 64.87° W) from 1989 to 1997 and from 2006 to 2009 were evaluated to quantify the magnitudes, significance, and implications of associated tends in atmospheric composition. The chemical data were stratified based on FLEXPART retroplumes into four discrete transport regimes: westerly flow from the eastern North America (NEUS/SEUS); easterly trade-wind flow from northern Africa and the subtropical NAO (Africa); long, open-ocean, anticyclonic flow around the Bermuda High (Oceanic); and transitional flow from the relatively clean open ocean to the polluted northeastern US (North). Based on all data, annual average concentrations of non-sea-salt (nss) SO42- associated with aerosols and annual VWA concentrations in precipitation decreased significantly (by 22 and 49%, respectively) whereas annual VWA concentrations of NH4+ in precipitation increased significantly (by 70%). Corresponding trends in aerosol and precipitation NO3- and of aerosol NH4+ were insignificant. Nss SO42- in precipitation under NEUS/SEUS and Oceanic flow decreased significantly (61% each) whereas corresponding trends in particulate nss SO42- under both flow regimes were insignificant. Trends for precipitation were driven in part by decreasing emissions of SO2 over upwind continents and associated decreases in anthropogenic contributions to nss SO42- concentrations. Under NEUS/SEUS and Oceanic flow, the ratio of anthropogenic to biogenic contributions to to nss SO42- in the column scavenged by precipitation were relatively greater than those in near surface aerosol, which implies that, for these flow regimes

  3. Imaging the lithosphere of rifted passive margins using waveform tomography: North Atlantic, South Atlantic and beyond

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergei; Schaeffer, Andrew; Celli, Nicolas Luca

    2016-04-01

    Lateral variations in seismic velocities in the upper mantle reflect variations in the temperature of the rocks at depth. Seismic tomography thus provides a proxy for lateral changes in the temperature and thickness of the lithosphere. It can map the deep boundaries between tectonic blocks with different properties and age of the lithosphere. Our 3D tomographic models of the upper mantle and the crust at the Atlantic and global scales are constrained by an unprecedentedly large global dataset of broadband waveform fits (over one million seismograms) and provide improved resolution of the lithosphere, compared to other available models. The most prominent high-velocity anomalies, seen down to 150-200 km depths, indicate the cold, thick, stable mantle lithosphere beneath Precambrian cratons, including those in North America, Greenland, northern and eastern Europe, Africa and South America. The dominant, large-scale, low-velocity feature is the global system of mid-ocean ridges, with broader low-velocity regions near hotspots, including Iceland. Currently active continental rifts show highly variable expression in the upper mantle, from pronounced low velocities to weak anomalies; this correlates with the amount of magmatism within the rift zone. Rifted passive margins have typically undergone cooling since the rifting and show more subtle variations in their seismic-velocity structure. Their thermal structure and evolution, however, are also shaped by 3D geodynamic processes since their formation, including cooling by the adjacent cratonic blocks inland and heating by warm oceanic asthenosphere.

  4. Atlantic opportunities for ENSO prediction

    NASA Astrophysics Data System (ADS)

    Martín-Rey, Marta; Rodríguez-Fonseca, Belén.; Polo, Irene

    2015-08-01

    El Niño-Southern Oscillation (ENSO) is the dominant mode of interannual climate variability with worldwide impacts. The knowledge of ENSO drivers and the underlying mechanisms is crucial to improve ENSO prediction, which still remains a challenge. The recently discovered connection between an Atlantic Niño (Niña) and a Pacific Niña (Niño), through an air-sea coupled mechanism during the first and last decades of the twentieth century, highlights an opportunity for ENSO prediction. Here a statistical cross-validated hindcast of ENSO along the twentieth century is presented, considering the Atlantic sea surface temperatures as the unique predictor field, and a set of atmospheric and oceanic variables related to the Atlantic-Pacific connection as the predictand field. The observed ENSO phase is well reproduced, and the skill is enhanced at the beginning and the end of the twentieth century. Understanding this multidecadal modulation of the Atlantic-Pacific connection could help to improve seasonal-to-decadal forecasts of ENSO and its associated impacts.

  5. FLORIDA ATLANTIC COASTAL ENVIRONMENTAL INITIATIVE

    EPA Science Inventory

    The Florida Atlantic Coastal Environmental Initiative (FACEI) will consist of a multiyear, multidisciplinary research and monitoring program designed to detect and trace a variety of nutrient sources (point and non-point sources) and other major environmental stressors to the coa...

  6. Intracontinental deformation in southern Africa during the Late Cretaceous

    NASA Astrophysics Data System (ADS)

    Brown, Roderick; Summerfield, Michael; Gleadow, Andrew; Gallagher, Kerry; Carter, Andrew; Beucher, Romain; Wildman, Mark

    2014-12-01

    Intracontinental deformation accommodated along major lithospheric scale shear zone systems and within associated extensional basins has been well documented within West, Central and East Africa during the Late Cretaceous. The nature of this deformation has been established by studies of the tectonic architecture of sedimentary basins preserved in this part of Africa. In southern Africa, where the post break-up history has been dominated by major erosion, little evidence for post-break-up tectonics has been preserved in the onshore geology. Here we present the results of 38 new apatite fission track analyses from the Damara region of northern Namibia and integrate these new data with our previous results that were focused on specific regions or sections only to comprehensively document the thermo-tectonic history of this region since continental break-up in the Early Cretaceous. The apatite fission track ages range from 449 ± 20 Ma to 59 ± 3 Ma, with mean confined track lengths between 14.61 ± 0.1 μm (SD 0.95 μm) to 10.83 ± 0.33 μm (SD 2.84 μm). The youngest ages (c. 80-60 Ma) yield the longest mean track lengths, and combined with their spatial distribution, indicate major cooling during the latest Cretaceous. A simple numerical thermal model is used to demonstrate that this cooling is consistent with the combined effects of heating caused by magmatic underplating, related to the Paraná-Etendeka continental flood volcanism associated with rifting and the opening of the South Atlantic, and enhanced erosion caused by major reactivation of major lithospheric structures within southern Africa during a key period of plate kinematic change that occurred in the South Atlantic and SW Indian ocean basins between 87 and 56 Ma. This phase of intraplate tectonism in northern Namibia, focused in discrete structurally defined zones, is coeval with similar phases elsewhere in Africa and suggests some form of trans-continental linkage between these lithospheric zones.

  7. Descriptions of members of the Simulium damnosum complex (Diptera: Simuliidae) from southern Africa, Ethiopia and Tanzania.

    PubMed

    Krüger, A; Car, M; Maegga, B T A

    2005-04-01

    This paper presents cytotaxonomic details of five populations of the Simulium damnosum complex from South Africa, Swaziland and Ethiopia. The 'Nkusi SW' and 'Pienaars' forms are newly designated members of the complex from South Africa, but the taxonomic rank of an isolate indistinguishable chromosomally from the 'Nkusi' cytoform remains unclear. From Ethiopia two cytoforms were identified, one of which shares two diagnostic chromosome inversions with the cytoform 'Kisiwani' from Tanzania. The second form belongs to S. kaffaense, and is the suspected local vector of Onchocerca volvulus. In addition, a re-analysis of the cytoform 'Kibwezi' from north-eastern Tanzania provided further insights into its population subdivision, and its genetic and morphological characteristics. Cytotaxonomic similarities between 'Kibwezi', S. mengense and S. pandanophilum, along with their biogeography, indicate a relict status of each of these taxa. PMID:15829137

  8. New Sediment Data to Constrain Southern Atlantic Holocene Secular Variation

    NASA Astrophysics Data System (ADS)

    Korte, M. C.; Frank, U.; Nowaczyk, N. R.; Frederichs, T.; Brown, M. C.

    2014-12-01

    The present day geomagnetic field shows a notable weak zone stretching from South America to southern Africa. This is known as the South Atlantic Anomaly caused by a growing patch of reversed magnetic flux at the core-mantle boundary. The investigation of existence and evolution of similar features over the past millennia using global spherical harmonic models is hampered by the fact that at present only very few paleomagnetic data from equatorial and many southern hemisphere regions are available to constrain models well in these regions. Here, we present the results of paleomagnetic investigations of sediment cores from four locations at low latitudes. OPD 1078 and 1079 lie off the coast of Angola, GeoB6517-2 and ODP 1076D are located in the Congo Fan and M35003-4 is situated southeast of Grenada in the Tobago Basin. In addition to the paleomagnetic work all cores were subjected to a comprehensive set of rock magnetic measurements. Detailed age models based on radiocarbon dating are available for all locations, since the sites were already subjects of different aspects of climatic studies. We include these new records and previously presented data from two Ethiopian locations in millennial scale global models of the CALSxk type. Agreement of the new data to previous models and modifications of models due to the additional data are discussed, focussing in particular on magnetic field structures resembling the present-day South Atlantic Anomaly.

  9. North Atlantic salinity as a predictor of Sahel rainfall.

    PubMed

    Li, Laifang; Schmitt, Raymond W; Ummenhofer, Caroline C; Karnauskas, Kristopher B

    2016-05-01

    Water evaporating from the ocean sustains precipitation on land. This ocean-to-land moisture transport leaves an imprint on sea surface salinity (SSS). Thus, the question arises of whether variations in SSS can provide insight into terrestrial precipitation. This study provides evidence that springtime SSS in the subtropical North Atlantic ocean can be used as a predictor of terrestrial precipitation during the subsequent summer monsoon in Africa. Specifically, increased springtime SSS in the central to eastern subtropical North Atlantic tends to be followed by above-normal monsoon-season precipitation in the African Sahel. In the spring, high SSS is associated with enhanced moisture flux divergence from the subtropical oceans, which converges over the African Sahel and helps to elevate local soil moisture content. From spring to the summer monsoon season, the initial water cycling signal is preserved, amplified, and manifested in excessive precipitation. According to our analysis of currently available soil moisture data sets, this 3-month delay is attributable to a positive coupling between soil moisture, moisture flux convergence, and precipitation in the Sahel. Because of the physical connection between salinity, ocean-to-land moisture transport, and local soil moisture feedback, seasonal forecasts of Sahel precipitation can be improved by incorporating SSS into prediction models. Thus, expanded monitoring of ocean salinity should contribute to more skillful predictions of precipitation in vulnerable subtropical regions, such as the Sahel. PMID:27386525

  10. North Atlantic salinity as a predictor of Sahel rainfall

    PubMed Central

    Li, Laifang; Schmitt, Raymond W.; Ummenhofer, Caroline C.; Karnauskas, Kristopher B.

    2016-01-01

    Water evaporating from the ocean sustains precipitation on land. This ocean-to-land moisture transport leaves an imprint on sea surface salinity (SSS). Thus, the question arises of whether variations in SSS can provide insight into terrestrial precipitation. This study provides evidence that springtime SSS in the subtropical North Atlantic ocean can be used as a predictor of terrestrial precipitation during the subsequent summer monsoon in Africa. Specifically, increased springtime SSS in the central to eastern subtropical North Atlantic tends to be followed by above-normal monsoon-season precipitation in the African Sahel. In the spring, high SSS is associated with enhanced moisture flux divergence from the subtropical oceans, which converges over the African Sahel and helps to elevate local soil moisture content. From spring to the summer monsoon season, the initial water cycling signal is preserved, amplified, and manifested in excessive precipitation. According to our analysis of currently available soil moisture data sets, this 3-month delay is attributable to a positive coupling between soil moisture, moisture flux convergence, and precipitation in the Sahel. Because of the physical connection between salinity, ocean-to-land moisture transport, and local soil moisture feedback, seasonal forecasts of Sahel precipitation can be improved by incorporating SSS into prediction models. Thus, expanded monitoring of ocean salinity should contribute to more skillful predictions of precipitation in vulnerable subtropical regions, such as the Sahel. PMID:27386525

  11. A cholera outbreak among semi-nomadic pastoralists in northeastern Uganda: epidemiology and interventions.

    PubMed

    Cummings, M J; Wamala, J F; Eyura, M; Malimbo, M; Omeke, M E; Mayer, D; Lukwago, L

    2012-08-01

    In sub-Saharan Africa, many nomadic pastoralists have begun to settle in permanent communities as a result of long-term water, food, and civil insecurity. Little is known about the epidemiology of cholera in these emerging semi-nomadic populations. We report the results of a case-control study conducted during a cholera outbreak among semi-nomadic pastoralists in the Karamoja sub-region of northeastern Uganda in 2010. Data from 99 cases and 99 controls were analysed. In multivariate analyses, risk factors identified were: residing in the same household as another cholera case [adjusted odds ratio (aOR) 6·67, 95% confidence interval (CI) 2·83-15·70], eating roadside food (aOR 2·91, 95% CI 1·24-6·81), not disposing of children's faeces in a latrine (aOR 15·76, 95% CI 1·54-161·25), not treating drinking water with chlorine (aOR 3·86, 95% CI 1·63-9·14), female gender (aOR 2·43, 95% CI 1·09-5·43), and childhood age (10-17 years) (aOR 7·14, 95% CI 1·97-25·83). This is the first epidemiological study of cholera reported from a setting of semi-nomadic pastoralism in sub-Saharan Africa. Public health interventions among semi-nomadic pastoralists should include a two-faceted approach to cholera prevention: intensive health education programmes to address behaviours inherited from insecure nomadic lifestyles, as well as improvements in water and sanitation infrastructure. The utilization of community-based village health teams provides an important method of implementing such activities. PMID:21943798

  12. Early Cretaceous rifts of Western and Central Africa: an overview

    NASA Astrophysics Data System (ADS)

    Guiraud, René; Maurin, Jean-Christophe

    1992-10-01

    The structure and evolution of Early Cretaceous rift basins in Western and Central Africa are described. Two stages of rift development and fracturing have been identified: (1) from Neocomian to Early Aptian roughly E-W and NW trending troughs (Upper Benue, N Cameroon, S Chad, Sudan etc.) opened in response to a submeridian extensional regime in Central Africa while in Western Africa the N-S trending transsaharian fault zone acted as a sinistral wrench; (2) from Middle Aptian to Late Albian large northwest trending troughs (E Niger, Sudan, Sirte, etc.) opened in response to a northeast extensional regime while the Central African fault zone (from Benue to Sudan) exhibited strike-slip movements, generating pull-apart basins. These rift and fracture systems delimit three large blocks within the African plate: a Western block, an Arabian-Nubian block and an Austral block. The Arabian-Nubian block tends to separate from the two other blocks, migrating towards the north during the first stage of basin development and then towards the NE during the second stage. The opening of the Atlantic Ocean was the dominant driving force for the Western and Austral blocks while the Arabian-Nubian block probably moved in response to the opening of the Indian Ocean and to the evolution of the Tethyan margin.

  13. Modulation of Atlantic Aerosols by the Madden-Julian Oscillation

    NASA Technical Reports Server (NTRS)

    Tian, B.; Waliser, D. E.; Kahn, Ralph A.; Wong, S.

    2010-01-01

    Much like the better-known EI Nino-Southern Oscillation, the Madden-Julian Oscillation (MJO) is a global-scale atmospheric phenomenon. The MJO involves periodic, systematic changes in the distribution of clouds and precipitation over the western Pacific and Indian oceans, along with differences in wind intensity over even more extensive areas, including the north and subtropical Atlantic Ocean. The lead authors of this paper developed a sophisticated mathematical technique for mapping the spatial and temporal behavior of changes in the atmosphere produced by the MJO. In a previous paper, we applied this technique to search for modulation of airborne particle amount in the eastern hemisphere associated with the "wet" (cloudy) vs. "dry" phases of the MJO. The study used primarily AVHRR, MODIS, and TOMS satellite-retrieved aerosol amount, but concluded that other factors, such as cloud contamination of the satellite signals, probably dominated the observed variations. The current paper looks at MJO modulation of desert dust transport eastward across the Atlantic from northern Africa, a region much less subject to systematic cloud contamination than the eastern hemisphere areas studied previously. In this case, a distinct aerosol signal appears, showing that dust is transported westward much more effectively during the MJO phase that favors westward-flowing wind, and such transport is suppressed when the MJO reduces these winds. Aside form the significant achievement in identifying such an effect, the result implies that an important component of global dust transport can be predicted based on the phase of the MJO. As a consequence, the impact of airborne dust on storm development in the Atlantic, and on dust deposition downwind of the desert sources, can also be predicted and more accurately modeled.

  14. 40 CFR 81.79 - Northeastern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false Northeastern Oklahoma Intrastate Air... Air Quality Control Regions § 81.79 Northeastern Oklahoma Intrastate Air Quality Control Region. The Metropolitan Tulsa Intrastate Air Quality Control Region has been renamed the Northeastern Oklahoma...

  15. 40 CFR 81.79 - Northeastern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false Northeastern Oklahoma Intrastate Air... Air Quality Control Regions § 81.79 Northeastern Oklahoma Intrastate Air Quality Control Region. The Metropolitan Tulsa Intrastate Air Quality Control Region has been renamed the Northeastern Oklahoma...

  16. 40 CFR 81.79 - Northeastern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false Northeastern Oklahoma Intrastate Air... Air Quality Control Regions § 81.79 Northeastern Oklahoma Intrastate Air Quality Control Region. The Metropolitan Tulsa Intrastate Air Quality Control Region has been renamed the Northeastern Oklahoma...

  17. 40 CFR 81.79 - Northeastern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false Northeastern Oklahoma Intrastate Air... Air Quality Control Regions § 81.79 Northeastern Oklahoma Intrastate Air Quality Control Region. The Metropolitan Tulsa Intrastate Air Quality Control Region has been renamed the Northeastern Oklahoma...

  18. 40 CFR 81.79 - Northeastern Oklahoma Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Northeastern Oklahoma Intrastate Air... Air Quality Control Regions § 81.79 Northeastern Oklahoma Intrastate Air Quality Control Region. The Metropolitan Tulsa Intrastate Air Quality Control Region has been renamed the Northeastern Oklahoma...

  19. Mesozoic and Cenozoic reconstructions of the South Atlantic

    NASA Astrophysics Data System (ADS)

    Lawver, Lawrence A.; Sclater, John G.; Meinke, Linda

    1985-04-01

    westward jump of the Mid-Atlantic Ridge just south of the Falkland-Agulhas Fracture Zone. The Mesozoic opening of the Somali Basin moved Madagascar from its presumed original position with Africa in Gondwanaland. The closure of Sri Lanka with India produces a unique fit for India and Sri Lanka with respect to Africa, Madagascar and Antarctica. This fit juxtaposes geological localities in Southeast India against similar localities in Enderhy Land. East Antarctica. The late Jurassic opening in the Somali Basin is tied to opening of the same age in the Mozambique Basin. Since this late Jurassic movement represents the initial break-up of Gondwanaland, it is assumed that similar movement must have occurred in what is now the western Weddell Sea and may also explain the opening evidenced by the Rocas Verdes region of southern South America.

  20. Massive Open Online Courses for Africa by Africa

    ERIC Educational Resources Information Center

    Oyo, Benedict; Kalema, Billy Mathias

    2014-01-01

    Africa is known for inadequate access to all sorts of human needs including health, education, food, shelter, transport, security, and energy. Before the emergence of massive open online courses (MOOCs), open access to higher education (HE) was exclusive of Africa. However, as a generally affordable method of post-secondary education delivery,…