Science.gov

Sample records for offshore foraging area

  1. White Shark Offshore Habitat: A Behavioral and Environmental Characterization of the Eastern Pacific Shared Offshore Foraging Area

    PubMed Central

    Nasby-Lucas, Nicole; Dewar, Heidi; Lam, Chi H.; Goldman, Kenneth J.; Domeier, Michael L.

    2009-01-01

    Background Although much is known about the behavior of white sharks in coastal regions, very little is known about their vertical movements offshore in the eastern Pacific where they spend up to five months. We provide the first detailed description of the offshore habitat use of white sharks in the eastern North Pacific. Methodology/Principal Findings This study uses 2-min data from four recovered pop-up satellite archival tags deployed at Guadalupe Island (2002 and 2005). Deployments ranged from 5.4 to 8.2 months. Two predominant vertical patterns were described. The first was a bimodal vertical pattern with time spent at the surface and at depth, which was observed while traveling. The second was a repetitive oscillatory diving mode displayed by sharks in the Shared Offshore Foraging Area (SOFA). For all four datasets the average maximum daily dive depths ranged from 442.5 to 492.8 m and were typically associated with dissolved oxygen concentrations of above 1.7 ml L−1. Although infrequent, occasional dives to near 1000 m with a minimum temperature of 3.9°C and a minimum O2 level of 0.3 ml L−1 were observed. Conclusions/Significance Recovered pop-up satellite tags from Guadalupe Island white sharks advance our understanding of the vertical habitat use of white sharks while offshore. The bimodal vertical pattern during traveling is most likely related to geolocation. The oscillatory dive pattern is likely associated with foraging. While feeding is not documented, foraging is likely occurring in association with the deep scattering layer. Diving depths were not limited by temperature but were constrained by O2 levels below approximately 1.5 ml L−1. While oxygen may limit the extent of sharks' vertical movements, it will also impact prey distribution. Consequently, the shallow oxygen minimum zone in the SOFA may act to concentrate prey, thus enhancing foraging opportunities in these oligotrophic waters. PMID:20011032

  2. Offshore Deformation Front in Miaoli Area

    NASA Astrophysics Data System (ADS)

    Chiang, P.; Gwo-shyn, S.

    2015-12-01

    Taiwan is located at the junction of the Eurasian Plate and the Philippine Sea Plate. It's because arc-continent collision occurs in the western Taiwan, resulting in the orogeny has formed a fold-and-thrust belt, developing a series of thrusts aligned in north-south direction. The thrust faults, locating in the central island, are the oldest and have almost inactive. Westward to the island, the faults become younger, dipping angles are smaller, and motions were stronger. On the west side, the foot of the Taiwan Western Foothill is considered the youngest thrust faults located along west Taiwan. Scholars recognized them as so-called the deformation front, and they also believed that the deformation front is located in between the compressive terrain uplifted area and the extensional subsidence area. Therefore, this front line is on the boundary of two different tectonic zones. This study investigates the trace of the deformation front in Miaoli area. Previous studies suggested that the west side of Miaoli collision zone should be fault-bounded, and is located in the seabed. However, in the geological map, there is no geologic evidence that appears on land and so-called active faults related with this deformation front. In the near coast seafloor, according to the reflection earthquakes data from the Institute of Oceanography of NTU, we can only see the offshore strata have been uplifted, and the data also shows that seabed is only covered by thin layer of sediments. This study indicates that in offshore place within three kilometers, shallow formations show a special layer of slime which was extruded to be corrugated transversely. Accordingly, we believe that this slime layer should be pressurized and filled with muddy water. Such features should be further investigated with other geological and geophysical survey data to check if they belong to the structural product of the deformation front.

  3. Foraging area fidelity for Kemp's ridleys in the Gulf of Mexico

    USGS Publications Warehouse

    Shaver, Donna J.; Hart, Kristen M.; Fujisaki, Ikuko; Rubio, Cynthia; Sartain-Iverson, Autumn R.; Peña, Jaime; Burchfield, Patrick M.; Gamez, Daniel Gomez; Ortiz, Jaime

    2013-01-01

    For many marine species, locations of key foraging areas are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to identify distinct foraging areas used by Kemp's ridley turtles (Lepidochelys kempii) tagged after nesting during 1998–2011 at Padre Island National Seashore, Texas, USA (PAIS; N = 22), and Rancho Nuevo, Tamaulipas, Mexico (RN; N = 9). Overall, turtles traveled a mean distance of 793.1 km (±347.8 SD) to foraging sites, where 24 of 31 turtles showed foraging area fidelity (FAF) over time (N = 22 in USA, N = 2 in Mexico). Multiple turtles foraged along their migratory route, prior to arrival at their "final" foraging sites. We identified new foraging "hotspots" where adult female Kemp's ridley turtles spent 44% of their time during tracking (i.e., 2641/6009 tracking days in foraging mode). Nearshore Gulf of Mexico waters served as foraging habitat for all turtles tracked in this study; final foraging sites were located in water <68 m deep and a mean distance of 33.2 km (±25.3 SD) from the nearest mainland coast. Distance to release site, distance to mainland shore, annual mean sea surface temperature, bathymetry, and net primary production were significant predictors of sites where turtles spent large numbers of days in foraging mode. Spatial similarity of particular foraging sites selected by different turtles over the 13-year tracking period indicates that these areas represent critical foraging habitat, particularly in waters off Louisiana. Furthermore, the wide distribution of foraging sites indicates that a foraging corridor exists for Kemp's ridleys in the Gulf. Our results highlight the need for further study of environmental and bathymetric components of foraging sites and prey resources contained therein, as well as international cooperation to protect essential at-sea foraging habitats for this imperiled species.

  4. Foraging area fidelity for Kemp's ridleys in the Gulf of Mexico

    PubMed Central

    Shaver, Donna J; Hart, Kristen M; Fujisaki, Ikuko; Rubio, Cynthia; Sartain, Autumn R; Peña, Jaime; Burchfield, Patrick M; Gamez, Daniel Gomez; Ortiz, Jaime

    2013-01-01

    For many marine species, locations of key foraging areas are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to identify distinct foraging areas used by Kemp's ridley turtles (Lepidochelys kempii) tagged after nesting during 1998–2011 at Padre Island National Seashore, Texas, USA (PAIS; N = 22), and Rancho Nuevo, Tamaulipas, Mexico (RN; N = 9). Overall, turtles traveled a mean distance of 793.1 km (±347.8 SD) to foraging sites, where 24 of 31 turtles showed foraging area fidelity (FAF) over time (N = 22 in USA, N = 2 in Mexico). Multiple turtles foraged along their migratory route, prior to arrival at their “final” foraging sites. We identified new foraging “hotspots” where adult female Kemp's ridley turtles spent 44% of their time during tracking (i.e., 2641/6009 tracking days in foraging mode). Nearshore Gulf of Mexico waters served as foraging habitat for all turtles tracked in this study; final foraging sites were located in water <68 m deep and a mean distance of 33.2 km (±25.3 SD) from the nearest mainland coast. Distance to release site, distance to mainland shore, annual mean sea surface temperature, bathymetry, and net primary production were significant predictors of sites where turtles spent large numbers of days in foraging mode. Spatial similarity of particular foraging sites selected by different turtles over the 13-year tracking period indicates that these areas represent critical foraging habitat, particularly in waters off Louisiana. Furthermore, the wide distribution of foraging sites indicates that a foraging corridor exists for Kemp's ridleys in the Gulf. Our results highlight the need for further study of environmental and bathymetric components of foraging sites and prey resources contained therein, as well as international cooperation to protect essential at-sea foraging habitats for this imperiled species. PMID:23919146

  5. Foraging area fidelity for Kemp's ridleys in the Gulf of Mexico.

    PubMed

    Shaver, Donna J; Hart, Kristen M; Fujisaki, Ikuko; Rubio, Cynthia; Sartain, Autumn R; Peña, Jaime; Burchfield, Patrick M; Gamez, Daniel Gomez; Ortiz, Jaime

    2013-07-01

    For many marine species, locations of key foraging areas are not well defined. We used satellite telemetry and switching state-space modeling (SSM) to identify distinct foraging areas used by Kemp's ridley turtles (Lepidochelys kempii) tagged after nesting during 1998-2011 at Padre Island National Seashore, Texas, USA (PAIS; N = 22), and Rancho Nuevo, Tamaulipas, Mexico (RN; N = 9). Overall, turtles traveled a mean distance of 793.1 km (±347.8 SD) to foraging sites, where 24 of 31 turtles showed foraging area fidelity (FAF) over time (N = 22 in USA, N = 2 in Mexico). Multiple turtles foraged along their migratory route, prior to arrival at their "final" foraging sites. We identified new foraging "hotspots" where adult female Kemp's ridley turtles spent 44% of their time during tracking (i.e., 2641/6009 tracking days in foraging mode). Nearshore Gulf of Mexico waters served as foraging habitat for all turtles tracked in this study; final foraging sites were located in water <68 m deep and a mean distance of 33.2 km (±25.3 SD) from the nearest mainland coast. Distance to release site, distance to mainland shore, annual mean sea surface temperature, bathymetry, and net primary production were significant predictors of sites where turtles spent large numbers of days in foraging mode. Spatial similarity of particular foraging sites selected by different turtles over the 13-year tracking period indicates that these areas represent critical foraging habitat, particularly in waters off Louisiana. Furthermore, the wide distribution of foraging sites indicates that a foraging corridor exists for Kemp's ridleys in the Gulf. Our results highlight the need for further study of environmental and bathymetric components of foraging sites and prey resources contained therein, as well as international cooperation to protect essential at-sea foraging habitats for this imperiled species.

  6. 7 CFR 407.13 - Area risk protection insurance for forage.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., and rotational grazing. Rotational grazing. The defoliation of the insured forage by livestock, within... moved from one area to another, allowing a period of grazing followed by a period for forage regrowth. 2. Insured Crop The insured crop will be the forage types shown on the actuarial documents: (a) Grown...

  7. Localised residency and inter-annual fidelity to coastal foraging areas may place sea bass at risk to local depletion

    PubMed Central

    Doyle, Thomas K.; Haberlin, Damien; Clohessy, Jim; Bennison, Ashley; Jessopp, Mark

    2017-01-01

    For many marine migratory fish, comparatively little is known about the movement of individuals rather than the population. Yet, such individual-based movement data is vitally important to understand variability in migratory strategies and fidelity to foraging locations. A case in point is the economically important European sea bass (Dicentrarchus labrax L.) that inhabits coastal waters during the summer months before migrating offshore to spawn and overwinter. Beyond this broad generalisation we have very limited information on the movements of individuals at coastal foraging grounds. We used acoustic telemetry to track the summer movements and seasonal migrations of individual sea bass in a large tidally and estuarine influenced coastal environment. We found that the vast majority of tagged sea bass displayed long-term residency (mean, 167 days) and inter-annual fidelity (93% return rate) to specific areas. We describe individual fish home ranges of 3 km or less, and while fish clearly had core resident areas, there was movement of fish between closely located receivers. The combination of inter-annual fidelity to localised foraging areas makes sea bass very susceptible to local depletion; however, the designation of protected areas for sea bass may go a long way to ensuring the sustainability of this species. PMID:28374772

  8. 33 CFR 334.905 - Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Pacific Ocean, offshore of Camp... REGULATIONS § 334.905 Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area. (a) The area. The waters of the Gulf of Santa Catalina, offshore of Camp Pendleton in the Pacific...

  9. 33 CFR 334.905 - Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Pacific Ocean, offshore of Camp... REGULATIONS § 334.905 Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area. (a) The area. The waters of the Gulf of Santa Catalina, offshore of Camp Pendleton in the Pacific...

  10. 33 CFR 334.905 - Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Pacific Ocean, offshore of Camp... REGULATIONS § 334.905 Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area. (a) The area. The waters of the Gulf of Santa Catalina, offshore of Camp Pendleton in the Pacific...

  11. 33 CFR 334.905 - Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Pacific Ocean, offshore of Camp... REGULATIONS § 334.905 Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area. (a) The area. The waters of the Gulf of Santa Catalina, offshore of Camp Pendleton in the Pacific...

  12. 33 CFR 334.905 - Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Pacific Ocean, offshore of Camp... REGULATIONS § 334.905 Pacific Ocean, offshore of Camp Pendleton, California; Fallbrook restricted area. (a) The area. The waters of the Gulf of Santa Catalina, offshore of Camp Pendleton in the Pacific...

  13. Biomass of deepwater demersal forage fishes in Lake Huron, 1994-2007: Implications for offshore predators

    USGS Publications Warehouse

    Roseman, E.F.; Riley, S.C.

    2009-01-01

    We estimated the biomass of deepwater demersal forage fishes (those species common in the diets of lake trout and Chinook salmon) in Lake Huron during the period 1994-2007. The estimated total lake-wide biomass of deepwater demersal fishes in 2007 was reduced by 87 percent of that observed in 1994. Alewife biomass remained near the record low observed in 2004. Biomass of young-of-the-year rainbow smelt was at a record high in 2005, but little recruitment appears to have occurred in 2006 or 2007. Record-high estimates of young-of-the-year bloater biomass were observed in 2005 and 2007, and an increase in the biomass of adult bloater in 2007 suggests that some recruitment may be occurring. The biomass of other potential deepwater demersal forage fish species (sculpins, ninespine stickleback, trout-perch and round goby) has also declined since 1994 and remained low in 2007. The forage fish community in 2007 was dominated by small (< 120 mm) bloater and rainbow smelt. These results suggest that lake trout and Chinook salmon in Lake Huron may face nutritional stress in the immediate future.

  14. Geographic structure of adelie penguin populations: overlap in colony-specific foraging areas

    USGS Publications Warehouse

    Ainley, D.G.; Ribic, C.A.; Ballard, G.; Heath, S.; Gaffney, I.; Karl, B.J.; Barton, K.J.; Wilson, P.R.; Webb, S.

    2004-01-01

    In an investigation of the factors leading to geographic structuring among Ade??lie Penguin (Pygoscelis adeliae) populations, we studied the size and overlap of colony-specific foraging areas within an isolated cluster of colonies. The study area, in the southwestern Ross Sea, included one large and three smaller colonies, ranging in size from 3900 to 135000 nesting pairs, clustered on Ross and Beaufort Islands. We used triangulation of radio signals from transmitters attached to breeding penguins to determine foraging locations and to define colony-specific foraging areas during the chick-provisioning period of four breeding seasons, 1997-2000. Colony populations (nesting pairs) were determined using aerial photography just after egg-laying; reproductive success was estimated by comparing ground counts of chicks fledged to the number of breeding pairs apparent in aerial photos. Foraging-trip duration, meal size, and adult body mass were estimated using RFID (radio frequency identification) tags and an automated reader and weighbridge. Chick growth was assessed by weekly weighing. We related the following variables to colony size: foraging distance, area, and duration; reproductive success; chick meal size and growth rate; and seasonal variation in adult body mass. We found that penguins foraged closest to their respective colonies, particularly at the smaller colonies. However, as the season progressed, foraging distance, duration, and area increased noticeably, especially at the largest colony. The foraging areas of the smaller colonies overlapped broadly, but very little foraging area overlap existed between the large colony and the smaller colonies, even though the foraging area of the large colony was well within range of the smaller colonies. Instead, the foraging areas of the smaller colonies shifted as that of the large colony grew. Colony size was not related to chick meal size, chick growth, or parental body mass. This differed from the year previous to

  15. Calculating foraging area using gloal navigation satellite system (GNSS) technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adjusting stocking rate to changing forage conditions is a critical part of pro-active range management. In general stocking rate approaches tend to assume more optimal landscape use patterns than will actually occur. Today we can monitor spatio-temporal landscape use on a 24/7 basis using animals...

  16. First steps for mitigating bycatch of Pink-footed Shearwaters Ardenna creatopus: Identifying overlap of foraging areas and fisheries in Chile

    USGS Publications Warehouse

    Carle, Ryan; Felis, Jonathan J.; López, Verónica; Adams, Josh; Hodum, Peter; Beck, Jessie; Colodro, Valentina; Vega, Rodrigo; González, Andrés

    2016-01-01

    The Pink-footed Shearwater, Ardenna creatopus, is listed as in danger of extinction by Chile and under Annex 1 of ACAP, with an estimated global population of approximately 56,000 individuals. Incidental bycatch of this species in fisheries is thought to be an important cause in population decline (i.e. annual estimated mortality of >1000 adults). This species is an endemic breeder in Chile, nesting only on the Juan Fernandez Archipelago (JFI; 30% of global population), and Isla Mocha (70% of global population). Using miniature GPS and satellite transmitters, we determined foraging areas of Pink-footed Shearwaters during the chick-rearing period in 2002 (JFI) and 2015-2016 (Isla Mocha). We overlaid shearwater tracking data with data from the Instituto de Fomento Pesquero (IFOP) on fishing effort in Chile (type of fishery, number sets per day, location of sets, and target species) to identify fisheries and fishing zones with the greatest potential for Pink-footed Shearwater bycatch. During the 2002-2006 (N = 28 birds total) and 2015 (N = 18 birds) breeding periods, foraging areas were associated with the continental shelf and shelf-break, generally less than 30 km offshore. All foraging trips occurred between 31.5 and 40.0 degrees south, and birds remained in Chile territorial waters 100% of the time. We identified two primary foraging hotspots, one offshore near Talcahuano, Chile (approximately 36-37.5° south), and one offshore north of Valdivia, Chile (approximately 39-39.5° south). Birds tracked from the Juan Fernández Archipelago foraged in the Talcahuano hotspot but did not visit the southerly hotspot near Valdivia. Birds tracked from Isla Mocha used both areas, with a greater proportion of birds using the Valdivia hotspot than the Talcahuano hotspot. Other major areas of use were around the respective breeding colonies from which the birds were tracked. Overlay of these data with fisheries data is currently in progress. Preliminary results indicate

  17. Jurassic faults of southwest Alabama and offshore areas

    SciTech Connect

    Mink, R.M.; Tew, B.H.; Bearden, B.L.; Mancini, E.A. )

    1991-03-01

    Four fault groups affecting Jurassic strata occur in the southwest and offshore Alabama areas. They include the regional basement rift trend, the regional peripheral fault trend, the Mobile graben fault system, and the Lower Mobile Bay fault system. The regional basement system rift and regional peripheral fault trends are distinct and rim the inner margin of the eastern Gulf Coastal Plain. The regional basement rift trend is genetically related to the breakup of Pangea and the opening of the Gulf of Mexico in the Late Triassic-Early Jurassic. This fault trend is thought to have formed contemporaneously with deposition of Late Triassic-Early Jurassic Eagle Mills Formation and to displace pre-Mesozoic rocks. The regional peripheral fault trend consists of a group of en echelon extensional faults that are parallel or subparallel to regional strike of Gulf Coastal Plain strata and correspond to the approximate updip limit of thick Louann Salt. Nondiapiric salt features are associated with the trend and maximum structural development is exhibited in the Haynesville-Smackover section. No hydrocarbon accumulations have been documented in the pre-Jurassic strata of southwest and offshore Alabama. Productive hydrocarbon reservoirs occur in Jurassic strata along the trends of the fault groups, suggesting a significant relationship between structural development in the Jurassic and hydrocarbon accumulation. Hydrocarbon traps are generally structural or contain a major structural component and include salt anticlines, faulted salt anticlines, and extensional fault traps. All of the major hydrocarbon accumulations are associated with movement of the Louann Salt along the regional peripheral fault trend, the Mobile graben fault system, or the Lower Mobile Bay fault system.

  18. 75 FR 51661 - Amendment of the Pacific High and Low Offshore Airspace Areas; California

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ... Pacific High and Low Offshore Airspace Areas; California AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action modifies the Pacific High and Low Offshore Airspace... modify the Pacific High and Low Control Areas (75 FR 32119). Interested parties were invited...

  19. 75 FR 32119 - Proposed Amendment of the Pacific High and Low Offshore Airspace Areas; California

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-07

    ... aircraft operations that extend beyond the lateral boundary of the existing Pacific High and Low Offshore Airspace Areas. Modifying the Pacific Offshore Airspace Areas by extending the boundaries further south of... boundaries further southeast of the current location to the Mexico FIR capturing pockets of...

  20. Wind Resource Mapping for United States Offshore Areas: Preprint

    SciTech Connect

    Elliott, D.; Schwartz, M.

    2006-06-01

    The U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) is producing validated wind resource maps for priority offshore regions of the United States. This report describes the methodology used to validate the maps and to build a Geographic Information Systems (GIS) database to classify the offshore wind resource by state, water depth, distance from shore, and administrative unit.

  1. Inferring Foraging Areas of Nesting Loggerhead Turtles Using Satellite Telemetry and Stable Isotopes

    PubMed Central

    Ceriani, Simona A.; Roth, James D.; Evans, Daniel R.; Weishampel, John F.; Ehrhart, Llewellyn M.

    2012-01-01

    In recent years, the use of intrinsic markers such as stable isotopes to link breeding and foraging grounds of migratory species has increased. Nevertheless, several assumptions still must be tested to interpret isotopic patterns found in the marine realm. We used a combination of satellite telemetry and stable isotope analysis to (i) identify key foraging grounds used by female loggerheads nesting in Florida and (ii) examine the relationship between stable isotope ratios and post-nesting migration destinations. We collected tissue samples for stable isotope analysis from 14 females equipped with satellite tags and an additional 57 untracked nesting females. Telemetry identified three post-nesting migratory pathways and associated non-breeding foraging grounds: (1) a seasonal continental shelf–constrained migratory pattern along the northeast U.S. coastline, (2) a non-breeding residency in southern foraging areas and (3) a residency in the waters adjacent to the breeding area. Isotopic variability in both δ13C and δ15N among individuals allowed identification of three distinct foraging aggregations. We used discriminant function analysis to examine how well δ13C and δ15N predict female post-nesting migration destination. The discriminant analysis classified correctly the foraging ground used for all but one individual and was used to predict putative feeding areas of untracked turtles. We provide the first documentation that the continental shelf of the Mid- and South Atlantic Bights are prime foraging areas for a large number (61%) of adult female loggerheads from the largest loggerhead nesting population in the western hemisphere and the second largest in the world. Our findings offer insights for future management efforts and suggest that this technique can be used to infer foraging strategies and residence areas in lieu of more expensive satellite telemetry, enabling sample sizes that are more representative at the population level. PMID:23028943

  2. 50 CFR Figure 1 to Subpart I of... - Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas extend beyond 3 miles offshore) and Optional.... I, Fig. 1 Figure 1 to Subpart I of Part 660—Existing California Area Closures (hatched areas...

  3. 50 CFR Figure 1 to Subpart I of... - Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas extend beyond 3 miles offshore) and Optional.... I, Fig. 1 Figure 1 to Subpart I of Part 660—Existing California Area Closures (hatched areas...

  4. 50 CFR Figure 1 to Subpart I of... - Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas extend beyond 3 miles offshore) and Optional.... I, Fig. 1 Figure 1 to Subpart I of Part 660—Existing California Area Closures (hatched areas...

  5. 50 CFR Figure 1 to Subpart I of... - Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas extend beyond 3 miles offshore) and Optional.... I, Fig. 1 Figure 1 to Subpart I of Part 660—Existing California Area Closures (hatched areas...

  6. 50 CFR Figure 1 to Subpart I of... - Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas extend beyond 3 miles offshore) and Optional.... I, Fig. 1 Figure 1 to Subpart I of Part 660—Existing California Area Closures (hatched areas...

  7. Common coastal foraging areas for loggerheads in the Gulf of Mexico: Opportunities for marine conservation

    USGS Publications Warehouse

    Hart, Kristen M.; Lamont, Margaret M.; Fujisaki, Ikuko; Tucker, Anton D.; Carthy, Raymond R.

    2012-01-01

    Designing conservation strategies that protect wide-ranging marine species is a significant challenge, but integrating regional telemetry datasets and synthesizing modeled movements and behavior offer promise for uncovering distinct at-sea areas that are important habitats for imperiled marine species. Movement paths of 10 satellite-tracked female loggerheads (Caretta caretta) from three separate subpopulations in the Gulf of Mexico, USA, revealed migration to discrete foraging sites in two common areas at-sea in 2008, 2009, and 2010. Foraging sites were 102–904 km away from nesting and tagging sites, and located off southwest Florida and the northern Yucatan Peninsula, Mexico. Within 3–35 days, turtles migrated to foraging sites where they all displayed high site fidelity over time. Core-use foraging areas were 13.0–335.2 km2 in size, in water <50 m deep, within a mean distance to nearest coastline of 58.5 km, and in areas of relatively high net primary productivity. The existence of shared regional foraging sites highlights an opportunity for marine conservation strategies to protect important at-sea habitats for these imperiled marine turtles, in both USA and international waters. Until now, knowledge of important at-sea foraging areas for adult loggerheads in the Gulf of Mexico has been limited. To better understand the spatial distribution of marine turtles that have complex life-histories, we propose further integration of disparate tracking data-sets at the oceanic scale along with modeling of movements to identify critical at-sea foraging habitats where individuals may be resident during non-nesting periods.

  8. Assessment of Offshore Wind Energy Leasing Areas for the BOEM Maryland Wind Energy Area

    SciTech Connect

    Musial, W.; Elliott, D.; Fields, J.; Parker, Z.; Scott, G.; Draxl, C.

    2013-06-01

    The National Renewable Energy Laboratory (NREL), under an interagency agreement with the Bureau of Ocean Energy Management (BOEM), is providing technical assistance to identify and delineate leasing areas for offshore wind energy development within the Atlantic Coast Wind Energy Areas (WEAs) established by BOEM. This report focuses on NREL's evaluation of the delineation proposed by the Maryland Energy Administration (MEA) for the Maryland (MD) WEA and two alternative delineations. The objectives of the NREL evaluation were to assess MEA's proposed delineation of the MD WEA, perform independent analysis, and recommend how the MD WEA should be delineated.

  9. Analysis of Offshore Wind Energy Leasing Areas for the Rhode Island/Massachusetts Wind Energy Area

    SciTech Connect

    Musial, W.; Elliott, D.; Fields, J.; Parker, Z.; Scott, G.

    2013-04-01

    The National Renewable Energy Laboratory (NREL), under an interagency agreement with the Bureau of Ocean Energy Management (BOEM), is providing technical assistance to BOEM on the identification and delineation of offshore leasing areas for offshore wind energy development within the Atlantic Coast Wind Energy Areas (WEAs) established by BOEM in 2012. This report focuses on NREL's evaluation of BOEM's Rhode Island/Massachusetts (RIMA) WEA leasing areas. The objective of the NREL evaluation was to assess the proposed delineation of the two leasing areas and determine if the division is reasonable and technically sound. Additionally, the evaluation aimed to identify any deficiencies in the delineation. As part of the review, NREL performed the following tasks: 1. Performed a limited review of relevant literature and RIMA call nominations. 2. Executed a quantitative analysis and comparison of the two proposed leasing areas 3. Conducted interviews with University of Rhode Island (URI) staff involved with the URI Special Area Management Plan (SAMP) 4. Prepared this draft report summarizing the key findings.

  10. Assessment of Offshore Wind Energy Leasing Areas for the BOEM New Jersey Wind Energy Area

    SciTech Connect

    Musial, W.; Elliott, D.; Fields, J.; Parker, Z.; Scott, G.; Draxl, C.

    2013-10-01

    The National Renewable Energy Laboratory (NREL), under an interagency agreement with the U.S. Department of the Interior's Bureau of Ocean Energy Management (BOEM), is providing technical assistance to identify and delineate leasing areas for offshore wind energy development within the Atlantic Coast Wind Energy Areas (WEAs) established by BOEM. This report focuses on NREL's development and evaluation of the delineations for the New Jersey (NJ) WEA. The overarching objective of this study is to develop a logical process by which the New Jersey WEA can be subdivided into non-overlapping leasing areas for BOEM's use in developing an auction process in a renewable energy lease sale. NREL identified a selection of leasing areas and proposed delineation boundaries within the established NJ WEA. The primary output of the interagency agreement is this report, which documents the methodology, including key variables and assumptions, by which the leasing areas were identified and delineated.

  11. Estimating Radiological Doses to Predators Foraging in a Low-Level Radioactive Waste Management Area

    SciTech Connect

    L.Soholt; G.Gonzales; P.Fresquez; K.Bennett; E.Lopez

    2003-03-01

    Since 1957, Los Alamos National Laboratory has operated Area G as its low-level, solid radioactive waste management and disposal area. Although the waste management area is developed, plants, small mammals, and avian and mammalian predators still occupy the less disturbed and revegetated portions of the land. For almost a decade, we have monitored the concentrations of selected radionuclides in soils, plants, and small mammals at Area G. The radionuclides tritium, plutonium-238, and plutonium-239 are regularly found at levels above regional background in all three media. Based on radionuclide concentrations in mice collected from 1994 to 1999, we calculated doses to higher trophic levels (owl, hawk, kestrel, and coyote) that forage on the waste management area. These predators play important functions in the regional ecosystems and are an important part of local Native American traditional tales that identify the uniqueness of their culture. The estimated doses are compared to Department of Energy's interim limit of 0.1 rad/day for the protection of terrestrial wildlife. We used exposure parameters that were derived from the literature for each receptor, including Environmental Protection Agency's exposure factors handbook. Estimated doses to predators ranged from 9E-06 to 2E-04 rad/day, assuming that they forage entirely on the waste management area. These doses are greater than those calculated for predators foraging exclusively in reference areas, but are still well below the interim dose limit. We believe that these calculated doses represent upper-bound estimates of exposure for local predators because the larger predators forage over areas that are much greater than the 63-acre waste management area. Based on these results, we concluded that predators foraging on this area do not face a hazard from radiological exposure under current site conditions.

  12. Chinstrap penguin foraging area associated with a seamount in Bransfield Strait, Antarctica

    NASA Astrophysics Data System (ADS)

    Kokubun, Nobuo; Lee, Won Young; Kim, Jeong-Hoon; Takahashi, Akinori

    2015-12-01

    Identifying marine features that support high foraging performance of predators is useful to determine areas of ecological importance. This study aimed to identify marine features that are important for foraging of chinstrap penguins (Pygoscelis antarcticus), an abundant upper-trophic level predator in the Antarctic Peninsula region. We investigated the foraging locations of penguins breeding on King George Island using GPS-depth loggers. Tracking data from 18 birds (4232 dives), 11 birds (2095 dives), and 19 birds (3947 dives) were obtained in 2007, 2010, and 2015, respectively. In all three years, penguins frequently visited an area near a seamount (Orca Seamount) in Bransfield Strait. The percentage of dives (27.8% in 2007, 36.1% in 2010, and 19.1% in 2015) and depth wiggles (27.1% in 2007, 37.2% in 2010, and 22.3% in 2015) performed in this area was higher than that expected from the size of the area and distance from the colony (8.4% for 2007, 14.7% for 2010, and 6.3% for 2015). Stomach content analysis showed that the penguins fed mainly on Antarctic krill. These results suggest that the seamount provided a favorable foraging area for breeding chinstrap penguins, with high availability of Antarctic krill, possibly related to local upwelling.

  13. Assessment of Offshore Wind Energy Leasing Areas for the BOEM Massachusetts Wind Energy Area

    SciTech Connect

    Musial, W.; Parker, Z.; Fields, M.; Scott, G.; Elliott, D.; Draxl, C.

    2013-12-01

    The U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL), under an interagency agreement with the Bureau of Ocean Energy Management (BOEM), is providing technical assistance to identify and delineate leasing areas for offshore wind energy development within the Atlantic Coast Wind Energy Areas (WEAs) established by BOEM. This report focuses on NREL's development of three delineated leasing area options for the Massachusetts (MA) WEA and the technical evaluation of these leasing areas. The overarching objective of this study is to develop a logical process by which the MA WEA can be subdivided into non-overlapping leasing areas for BOEM's use in developing an auction process in a renewable energy lease sale. NREL worked with BOEM to identify an appropriate number of leasing areas and proposed three delineation alternatives within the MA WEA based on the boundaries announced in May 2012. A primary output of the interagency agreement is this report, which documents the methodology, including key variables and assumptions, by which the leasing areas were identified and delineated.

  14. Stable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California

    USGS Publications Warehouse

    Adams, Josh; Takekawa, John Y.; Carter, Harry R.

    2004-01-01

    Planktivorous seabirds readily respond to changes in marine ecosystems and have the ability to integrate information regarding variability in abundance, availability, and community composition of key prey resources. We studied the foraging and breeding ecology of the Cassin's auklet, Ptychoramphus aleuticus (Pallas, 1811), off southern California during three breeding seasons (1999-2001), when large intra- and inter-annual variability occurred in local oceanographic conditions during a prolonged La Nina event. Radio-marked parents used consistent core foraging areas within 30 km of their colony, aggregated in shelf waters (< 200 m depth), and occasionally foraged in deeper waters. Parents delivered primarily euphausiids, pelagic larval-juvenile fishes, and minor amounts of cephalopods and other crustaceans. Whereas the euphausiid Thysanoessa spinifera Holmes, 1900 was most important during 1999 and 2001, Euphausia pacifica Hansen, 1911 replaced adult T. spinifera in 2000 after an anomalous eastward inflection of the California Current occurred near the auklets' foraging area. Differences in chick diets, however, did not significantly influence fledging success and growth among first chicks, but the proportion of pairs successfully fledging an alpha chick and initiating a second clutch was exceptional in 1999 (63%) and 2000 (75%), and less in 2001 (7%). We suggest that dietary composition was influenced by modified prey availability driven in part by fluctuations in regional upwelling and circulation. ?? 2004 NRC Canada.

  15. Three-Dimensional Wind Profiling of Offshore Wind Energy Areas With Airborne Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Beyon, Jeffrey Y.; Cowen, Larry J.; Kavaya, Michael J.; Grant, Michael S.

    2014-01-01

    A technique has been developed for imaging the wind field over offshore areas being considered for wind farming. This is accomplished with an eye-safe 2-micrometer wavelength coherent Doppler lidar installed in an aircraft. By raster scanning the aircraft over the wind energy area (WEA), a three-dimensional map of the wind vector can be made. This technique was evaluated in 11 flights over the Virginia and Maryland offshore WEAs. Heights above the ocean surface planned for wind turbines are shown to be within the marine boundary layer, and the wind vector is seen to show variation across the geographical area of interest at turbine heights.

  16. Three-dimensional wind profiling of offshore wind energy areas with airborne Doppler lidar

    NASA Astrophysics Data System (ADS)

    Koch, Grady J.; Beyon, Jeffrey Y.; Cowen, Larry J.; Kavaya, Michael J.; Grant, Michael S.

    2014-01-01

    A technique has been developed for imaging the wind field over offshore areas being considered for wind farming. This is accomplished with an eye-safe 2-μm wavelength coherent Doppler lidar installed in an aircraft. By raster scanning the aircraft over the wind energy area (WEA), a three-dimensional map of the wind vector can be made. This technique was evaluated in 11 flights over the Virginia and Maryland offshore WEAs. Heights above the ocean surface planned for wind turbines are shown to be within the marine boundary layer, and the wind vector is seen to show variation across the geographical area of interest at turbine heights.

  17. The Characterization of Microearthquakes in Offshore Area of Northeastern South Korea from Multidisciplinary Data Set

    NASA Astrophysics Data System (ADS)

    Cho, H. M.; Che, I. Y.; Kim, G.

    2015-12-01

    A number of small earthquakes in offshore Gangneung-Sokcho-Goseong area of northeastern South Korea has been identified and the hypocenters of these events are relocated by double-difference algorithm using multidisciplinary data set. Korea Institute of Geoscience and Mineral Resources (KIGAM) lists 845 events for the period Jan. 2010 - Jun. 2015 with local magnitude up to 3.3. Peer review shows that the offshore events can be grouped into a number of small clusters, whereas onshore events are relatively few and unevenly distributed. It appears to have little relationship between the location of offshore event clusters and the direction of main onshore faults running NNE - SSW. In this study, we focus on the small events occurred in the area of N37°45´-38°35´ and E128°30´ - 129°20´. The Korea Integrated Seismic System (KISS) network operated by KIGAM and 5 temporary stations with Guralp CMG-40T short-period seismometers placed along the east coast of South Korea record the seismic energy generated from small events. The 137 events recorded from May to October 2014, ranging in local magnitude from 0.4 to 2.3, are already relocated using 1849 direct P-wave traveltimes identified from 29 stations. Relocation produced two major clusters in offshore Goseong (cluster 1) and Yangyang (cluster 2) province. The waveforms of relocated events in cluster 1 and 2 are similar to those from explosion in waters rather than earthquake, and spectrum analysis shows energy concentration on low frequencies below 10 Hz. We are combining the multidisciplinary data set from land based broadband and short-period seismometers, Guralp OBS system deployed in July this year, accelerometer and hydrophone array mounted on the offshore platforms of the underwater seismic observatory in the north of the study area. The integration of seismic and hydro-acoustic data in offshore supplements uneven azimuthal coverage and gives improved characterization of offshore seismic activity.

  18. Herbaceous plant species invading natural areas tend to have stronger adaptive root foraging than other naturalized species

    PubMed Central

    Keser, Lidewij H.; Visser, Eric J. W.; Dawson, Wayne; Song, Yao-Bin; Yu, Fei-Hai; Fischer, Markus; Dong, Ming; van Kleunen, Mark

    2015-01-01

    Although plastic root-foraging responses are thought to be adaptive, as they may optimize nutrient capture of plants, this has rarely been tested. We investigated whether nutrient-foraging responses are adaptive, and whether they pre-adapt alien species to become natural-area invaders. We grew 12 pairs of congeneric species (i.e., 24 species) native to Europe in heterogeneous and homogeneous nutrient environments, and compared their foraging responses and performance. One species in each pair is a USA natural-area invader, and the other one is not. Within species, individuals with strong foraging responses, measured as plasticity in root diameter and specific root length, had a higher biomass. Among species, the ones with strong foraging responses, measured as plasticity in root length and root biomass, had a higher biomass. Our results therefore suggest that root foraging is an adaptive trait. Invasive species showed significantly stronger root-foraging responses than non-invasive species when measured as root diameter. Biomass accumulation was decreased in the heterogeneous vs. the homogeneous environment. In aboveground, but not belowground and total biomass, this decrease was smaller in invasive than in non-invasive species. Our results show that strong plastic root-foraging responses are adaptive, and suggest that it might aid in pre-adapting species to becoming natural-area invaders. PMID:25964790

  19. Herbaceous plant species invading natural areas tend to have stronger adaptive root foraging than other naturalized species.

    PubMed

    Keser, Lidewij H; Visser, Eric J W; Dawson, Wayne; Song, Yao-Bin; Yu, Fei-Hai; Fischer, Markus; Dong, Ming; van Kleunen, Mark

    2015-01-01

    Although plastic root-foraging responses are thought to be adaptive, as they may optimize nutrient capture of plants, this has rarely been tested. We investigated whether nutrient-foraging responses are adaptive, and whether they pre-adapt alien species to become natural-area invaders. We grew 12 pairs of congeneric species (i.e., 24 species) native to Europe in heterogeneous and homogeneous nutrient environments, and compared their foraging responses and performance. One species in each pair is a USA natural-area invader, and the other one is not. Within species, individuals with strong foraging responses, measured as plasticity in root diameter and specific root length, had a higher biomass. Among species, the ones with strong foraging responses, measured as plasticity in root length and root biomass, had a higher biomass. Our results therefore suggest that root foraging is an adaptive trait. Invasive species showed significantly stronger root-foraging responses than non-invasive species when measured as root diameter. Biomass accumulation was decreased in the heterogeneous vs. the homogeneous environment. In aboveground, but not belowground and total biomass, this decrease was smaller in invasive than in non-invasive species. Our results show that strong plastic root-foraging responses are adaptive, and suggest that it might aid in pre-adapting species to becoming natural-area invaders.

  20. 76 FR 34627 - Proposed Modification of Offshore Airspace Areas: Norton Sound Low, Control 1234L and Control...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-14

    ... Areas: Norton Sound Low, Control 1234L and Control 1487L; Alaska AGENCY: Federal Aviation Administration... Sound Low, Control 1234L, and Control 1487L Offshore Airspace Areas in Alaska. The airspace floors would... Norton Sound Low, Control 1234L, and Control 1487L Offshore Airspace Areas in Alaska. The Norton...

  1. Potential Offshore Wind Energy Areas in California: An Assessment of Locations, Technology, and Costs

    SciTech Connect

    Musial, Walter; Beiter, Philipp; Tegen, Suzanne; Smith, Aaron

    2016-12-01

    This report summarizes a study of possible offshore wind energy locations, technologies, and levelized cost of energy in the state of California between 2015 and 2030. The study was funded by the U.S. Department of the Interior's Bureau of Ocean Energy Management (BOEM), the federal agency responsible for regulating renewable energy development on the Outer Continental Shelf. It is based on reference wind energy areas where representative technology and performance characteristics were evaluated. These reference areas were identified as sites that were suitable to represent offshore wind cost and technology based on physical site conditions, wind resource quality, known existing site use, and proximity to necessary infrastructure. The purpose of this study is to assist energy policy decision-making by state utilities, independent system operators, state government officials and policymakers, BOEM, and its key stakeholders. The report is not intended to serve as a prescreening exercise for possible future offshore wind development.

  2. Fine-scale spatial age segregation in the limited foraging area of an inshore seabird species, the little penguin.

    PubMed

    Pelletier, Laure; Chiaradia, André; Kato, Akiko; Ropert-Coudert, Yan

    2014-10-01

    Competition for food resources can result in spatial and dietary segregation among individuals from the same species. Few studies have looked at such segregations with the combined effect of sex and age in species with short foraging ranges. In this study we examined the 3D spatial use of the environment in a species with a limited foraging area. We equipped 26 little penguins (Eudyptula minor) of known age, sex, and breeding output with GPS (location) and accelerometer (body acceleration and dive depth) loggers. We obtained dietary niche information from the isotopic analysis of blood tissue. We controlled for confounding factors of foraging trip length and food availability by sampling adults at guard stage when parents usually make one-day trips. We observed a spatial segregation between old (>11 years old) and middle-aged penguins (between 5 and 11 years old) in the foraging area. Old penguins foraged closer to the shore, in shallower water. Despite observing age-specific spatial segregation, we found no differences in the diving effort and foraging efficiency between age classes and sexes. Birds appeared to target similar prey types, but showed age-specific variation in their isotopic niche width. We hypothesize that this age-specific segregation was primarily determined by a "cohort effect" that would lead individuals sharing a common life history (i.e. having fledged and dispersed around the same age) to forage preferentially together or to share similar foraging limitations.

  3. Critical fishery species in Alaska offshore oil and gas lease areas

    SciTech Connect

    Arbegast, J.; Allen, M.

    1980-11-01

    Offshore oil and gas development in Alaska is governed through sales of lease blocks in designated areas. USBLM manages these sales and prepares the necessary environmental impact statement prior to each sale. Collected fishery data are tabulated, linking critical crustacean and fishery species with their associated lease areas. Listed are critical species, organized by taxonomic name, associated common name, and taxonomic code numbers. Each critical species is linked to one or more of the lease area numbers, derived from USBLM planning units.

  4. 33 CFR 334.845 - Wisconsin Air National Guard, Volk Field military exercise area located in Lake Michigan offshore...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., Volk Field military exercise area located in Lake Michigan offshore from Manitowoc and Sheboygan... Air National Guard, Volk Field military exercise area located in Lake Michigan offshore from Manitowoc.... (b) The regulation. (1) During specific, infrequent periods when Military exercises will be...

  5. Responses of wintering geese to the designation of goose foraging areas in The Netherlands.

    PubMed

    Koffijberg, Kees; Schekkerman, Hans; van der Jeugd, Henk; Hornman, Menno; van Winden, Erik

    2017-03-01

    The Netherlands is important for wintering migratory herbivorous geese, numbers of which have rapidly increased, leading to conflict with agriculture. In 2005/2006, a new goose management policy aimed to limit compensation payments to farmers by concentrating foraging geese in 80 000 ha of designated 'go' areas-where farmers received payment to accommodate them-and scaring geese from 'no go' areas elsewhere. Monthly national counts of four abundant goose species during 10 years prior to the new policy and in 8 years following implementation found that 57% of all goose days were spent within 'go' areas under the new management, the same as prior to implementation. Such lack of response suggests no predicted learning effects, perhaps because of (i) increases in abundance outside of 'go' areas, (ii) irregularly shaped boundaries and enclaves of 'no go' farmland within 'go' areas and/or (iii) insufficient differences in disturbance levels within and outside designated areas.

  6. Ecological determinants of the occurrence and dynamics of Vibrio parahaemolyticus in offshore areas

    PubMed Central

    Martinez-Urtaza, Jaime; Blanco-Abad, Veronica; Rodriguez-Castro, Alba; Ansede-Bermejo, Juan; Miranda, Ana; Rodriguez-Alvarez, M Xose

    2012-01-01

    The life cycle of Vibrio parahaemolyticus has been conventionally associated with estuarine areas characterized by moderate salinity and warm seawater temperatures. Recent evidence suggests that the distribution and population dynamics of V. parahaemolyticus may be shaped by the existence of an oceanic transport of communities of this organism mediated by zooplankton. To evaluate this possibility, the presence of V. parahaemolyticus in the water column of offshore areas of Galicia was investigated by PCR monthly over an 18-month period. Analysis of zooplankton and seawater showed that the occurrence of V. parahaemolyticus in offshore areas was almost exclusively associated with zooplankton and was present in 80% of the samples. The influence of environmental factors assessed by generalized additive models revealed that the abundance and seasonality of V. parahaemolyticus in zooplankton was favoured by the concurrence of downwelling periods that promoted the zooplankton patchiness. These results confirm that offshore waters may be common habitats for V. parahaemolyticus, including strains with virulent traits. Additionally, genetically related populations were found in offshore zooplankton and in estuaries dispersed along 1500 km. This finding suggests that zooplankton may operate as a vehicle for oceanic dispersal of V. parahaemolyticus populations, connecting distant regions and habitats, and thereby producing impacts on the local community demography and the spread of Vibrio-related diseases. PMID:22094349

  7. Onshore and offshore geologic map of the Coal Oil Point area, southern California

    USGS Publications Warehouse

    Dartnell, Pete; Conrad, James E.; Stanley, Richard G.; Guy R. Cochrane, Guy R.

    2011-01-01

    Geologic maps that span the shoreline and include both onshore and offshore areas are potentially valuable tools that can lead to a more in depth understanding of coastal environments. Such maps can contribute to the understanding of shoreline change, geologic hazards, both offshore and along-shore sediment and pollutant transport. They are also useful in assessing geologic and biologic resources. Several intermediate-scale (1:100,000) geologic maps that include both onshore and offshore areas (herein called onshore-offshore geologic maps) have been produced of areas along the California coast (see Saucedo and others, 2003; Kennedy and others, 2007; Kennedy and Tan, 2008), but few large-scale (1:24,000) maps have been produced that can address local coastal issues. A cooperative project between Federal and State agencies and universities has produced an onshore-offshore geologic map at 1:24,000 scale of the Coal Oil Point area and part of the Santa Barbara Channel, southern California (fig. 1). As part of the project, the U.S. Geological Survey (USGS) and the California Geological Survey (CGS) hosted a workshop (May 2nd and 3rd, 2007) for producers and users of coastal map products (see list of participants) to develop a consensus on the content and format of onshore-offshore geologic maps (and accompanying GIS files) so that they have relevance for coastal-zone management. The USGS and CGS are working to develop coastal maps that combine geospatial information from offshore and onshore and serve as an important tool for addressing a broad range of coastal-zone management issues. The workshop was divided into sessions for presentations and discussion of bathymetry and topography, geology, and habitat products and needs of end users. During the workshop, participants reviewed existing maps and discussed their merits and shortcomings. This report addresses a number of items discussed in the workshop and details the onshore and offshore geologic map of the Coal Oil

  8. Integrated chemical and biological assessment of contaminant impacts in selected European coastal and offshore marine areas.

    PubMed

    Hylland, Ketil; Robinson, Craig D; Burgeot, Thierry; Martínez-Gómez, Concepción; Lang, Thomas; Svavarsson, Jörundur; Thain, John E; Vethaak, A Dick; Gubbins, Mattew J

    2017-03-01

    This paper reports a full assessment of results from ICON, an international workshop on marine integrated contaminant monitoring, encompassing different matrices (sediment, fish, mussels, gastropods), areas (Iceland, North Sea, Baltic, Wadden Sea, Seine estuary and the western Mediterranean) and endpoints (chemical analyses, biological effects). ICON has demonstrated the use of a framework for integrated contaminant assessment on European coastal and offshore areas. The assessment showed that chemical contamination did not always correspond with biological effects, indicating that both are required. The framework can be used to develop assessments for EU directives. If a 95% target were to be used as a regional indicator of MSFD GES, Iceland and offshore North Sea would achieve the target using the ICON dataset, but inshore North Sea, Baltic and Spanish Mediterranean regions would fail.

  9. Impact hypothesis for offshore wind farms: Explanatory models for species distribution at extremely exposed rocky areas

    NASA Astrophysics Data System (ADS)

    Schläppy, Marie-Lise; Šaškov, Aleksej; Dahlgren, Thomas G.

    2014-07-01

    The increasing need for renewable and clean energy production is likely to result in a diversification of locations for the implementation of offshore wind farms which have been so far predominantly sited on soft substrata. In contrast, offshore wind turbines placed on rocky reefs in highly exposed areas are much less common and the impacts on local flora and fauna can only be hypothesized. On the Western coast of Norway, a rocky reef with a highly complex topography has been chosen to be the first full-scale offshore wind farm in the country. Underwater video analyses and multibeam bathymetry data with a generalized linear model were used opportunistically to investigate the influence of geomorphic explanatory variables on the occurrence of selected taxa (algae, sea urchins and sea stars) identified in the study area. Combining video observations and multibeam bathymetry in a generalized linear model revealed that the geomorphic descriptors: aspect, slope, rugosity, and benthic position indexes (BPI), were of significance for algae, sea urchins and sea stars at Havsul and served in showing their habitat preferences. Kelp occurred in areas of high rugosity, on gentle slopes, at elevated areas with a southerly orientation and on the sheltered side of rock or bedrock. Thus, construction disturbance that modify those variables may lead to a change in the area preferred by kelp. Turbines that shade southerly aspects may affect small kelp plants in reducing their available habitat. Sea urchins were more abundant on steep slopes and both sea stars and sea urchins showed a preference for a complex local relief (high rugosity) and heterogeneity in fine and broad elevation (shown by BPI). Thus, foundations and cable route preparation may significantly change the slope, rugosity of BPI broad, which will change the basis for sea urchin populations. It may likewise significantly change the rugosity or BPI (fine or broad), which may change the distribution of sea stars. The

  10. Regional scale hydrodynamic modelling of offshore wind farm development areas off the east coast of Scotland

    NASA Astrophysics Data System (ADS)

    O'Hara Murray, Rory; Gallego, Alejandro

    2013-04-01

    There is considerable interest in Scotland, supported by the Scottish Government, in the expansion of renewable energy production. In particular, significant offshore wind energy developments are already planned in coastal waters to the east of the Forth and Tay estuaries. It is important to understand the local and cumulative environmental impact of such developments within this region, to aid licensing decisions but also to inform marine spatial planning in general. Substantial wind farm developments may affect physical processes within the region, such as tidal-, wind-, and wave-driven circulation, as well as coastal sediment transport and more complex estuarine dynamics. Such physical impacts could have ecological and, ultimately, socio-economic consequences. The Firth of Forth and Tay areas both exhibit complex estuarine characteristics due to fresh water input, complex bathymetry and coastline, and tidal mixing. Our goal is to construct an unstructured grid hydrodynamic model of the wider Firth of Forth and Tay region using the Finite-Volume Coastal Ocean Model (FVCOM), resolving the complex estuarine hydrography of the area and representing offshore wind developments. Hydrodynamic modelling will provide an accurate baseline of the hydrography in this region but also allow the assessment of the effect on the physical environment of multiple wind farm development scenarios.

  11. Foraging ranges of immature African white-backed vultures (Gyps africanus) and their use of protected areas in southern Africa.

    PubMed

    Phipps, W Louis; Willis, Stephen G; Wolter, Kerri; Naidoo, Vinny

    2013-01-01

    Vultures in the Gyps genus are declining globally. Multiple threats related to human activity have caused widespread declines of vulture populations in Africa, especially outside protected areas. Addressing such threats requires the estimation of foraging ranges yet such estimates are lacking, even for widespread (but declining) species such as the African white-backed vulture (Gyps africanus). We tracked six immature African white-backed vultures in South Africa using GPS-GSM units to study their movement patterns, their use of protected areas and the time they spent in the vicinity of supplementary feeding sites. All individuals foraged widely; their combined foraging ranges extended into six countries in southern Africa (mean (± SE) minimum convex polygon area =269,103±197,187 km(2)) and three of the vultures travelled more than 900 km from the capture site. All six vultures spent the majority of their tracking periods outside protected areas. South African protected areas were very rarely visited whereas protected areas in northern Botswana and Zimbabwe were used more frequently. Two of the vultures visited supplementary feeding sites regularly, with consequent reduced ranging behaviour, suggesting that individuals could alter their foraging behaviour in response to such sites. We show that immature African white-backed vultures are capable of travelling throughout southern Africa, yet use protected areas to only a limited extent, making them susceptible to the full range of threats in the region. The standard approach of designating protected areas to conserve species is unlikely to ensure the protection of such wide-ranging species against threats in the wider landscape.

  12. Microbial community in the potential gas hydrate area Kaoping Canyon bearing sediment at offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Wu, S. Y.; Hung, C. C.; Lai, S. J.; Ding, J. Y.; Lai, M. C.

    2015-12-01

    The deep sub-seafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass plays a potentially important role in long-term controls of global biogeochemical cycles. The research team from Taiwan, supported by the Central Geological Survey (CGS), has been demonstrated at SW offshore Taiwan that indicated this area is potential gas hydrate region. Therefore, the Gas Hydrate Master Program (GHMP) was brought in the National Energy Program-Phase II (NEP-II) to continue research and development. In this study, the microbial community structure of potential gas hydrate bearing sediments of giant piston core MD-178-10-3291 (KP12N) from the Kaoping Canyon offshore SW of Taiwan were investigated. This core was found many empty spaces and filling huge methane gas (>99.9 %) that might dissociate from solid gas hydrate. 16S rRNA gene clone libraries and phylogenetic analysis showed that the dominant members of Archaea were ANME (13 %), SAGMEG (31 %) and DSAG (20 %), and those of Bacteria were Chloroflexi (13 %), Candidate division JS1 (40 %) and Planctomycetes (15 %). Among them, ANME-3 is only distributed at the sulfate-methane interface (SMI) of 750 cmbsf, and sharing similarity with the Hydrate Ridge clone HydBeg92. ANME-1 and SAGMEG distributed below 750 cmbsf. In addition, DSAG and Candidate division JS1 are most dominant and distributed vertically at all tested depths from 150-3600 cmbsf. Combine the geochemical data and microbial phylotype distribution suggests the potential of gas hydrate bearing sediments at core MD-178-10-3291 (KP12N) from the Kaoping Canyon offshore SW of Taiwan.

  13. Preferential Use of Carbon Sources in Culturable Aerobic Mesophilic Bacteria of Coptotermes curvignathus's (Isoptera: Rhinotermitidae) Gut and Its Foraging Area.

    PubMed

    Wong, W Z; H'ng, P S; Chin, K L; Sajap, Ahmad Said; Tan, G H; Paridah, M T; Othman, Soni; Chai, E W; Go, W Z

    2015-10-01

    The lower termite, Coptotermes curvignathus, is one of the most prominent plantation pests that feed upon, digest, and receive nourishment from exclusive lignocellulose diets. The objective of this study was to examine the utilization of sole carbon sources by isolated culturable aerobic bacteria among communities from the gut and foraging pathway of C. curvignathus. We study the bacteria occurrence from the gut of C. curvignathus and its surrounding feeding area by comparing the obtained phenotypic fingerprint with Biolog's extensive species library. A total of 24 bacteria have been identified mainly from the family Enterobacteriaceae from the identification of Biolog Gen III. Overall, the bacteria species in the termite gut differ from those of foraging pathway within a location, except Acintobacter baumannii, which was the only bacteria species found in both habitats. Although termites from a different study area do not have the same species of bacteria in the gut, they do have a bacterial community with similar role in degrading certain carbon sources. Sugars were preferential in termite gut isolates, while nitrogen carbon sources were preferential in foraging pathway isolates. The preferential use of specific carbon sources by these two bacterial communities reflects the role of bacteria for regulation of carbon metabolism in the termite gut and foraging pathway.

  14. Reproduction, foraging and the negative density-area relationship of a generalist rodent.

    PubMed

    Wilder, Shawn M; Meikle, Douglas B

    2005-07-01

    While many species show positive relationships between population density and habitat patch area, some species consistently show higher densities in smaller patches. Few studies have examined mechanisms that may cause species to have negative density-area relationships. We tested the hypothesis that greater reproduction in edge versus interior habitats and small versus large fragments contributes to higher densities of white-footed mice (Peromyscus leucopus) in small versus large forest fragments. We also examined vegetation structure and foraging tray utilization to evaluate if greater reproduction was a result of higher food availability. There were greater number of litters and proportion of females producing litters in the edge versus interior of forest fragments, which may have contributed to greater population growth rates and higher densities in edge versus interior and small versus large fragments. Data on vegetation structure and giving-up densities of seeds in artificial patches suggest that food availability may be higher in edge versus interior habitats and small versus large fragments. These results, in an area with few or no long-tailed weasels, provide a distinct contrast to the findings of Morris and Davidson (Ecology 81:2061, 2000) who observed lower reproduction in forest edge habitat as a result of high weasel predation, suggesting that specialist predators may be important in affecting the quality of edge habitat. While we cannot exclude the potential contributions of immigration, emigration, and mortality, our data suggest that greater reproduction in edge versus interior habitat is an important factor contributing to higher densities of P. leucopus in small fragments.

  15. Exploration results and petroleum potential of Arctic shelf areas offshore Norway and USSR

    SciTech Connect

    Bergsager, E. )

    1990-05-01

    Exploration is in its very early stages in arctic shell areas offshore Norway and the Soviet Union. The first well was spudded in 1980 in the Norwegian Barents Sea and in 1982 in the Soviet Union. Giant discoveries of gas and significant oil discoveries have been made. The only production so far is that of oil onshore the island of Kolguyev. Reservoir rocks are clastic Triassic and the field has an offshore extension. Reservoir rocks with proven hydrocarbons are Permian carbonates, Triassic, Jurassic, and Lower Cretaceous clastic rocks. Widespread rich oil-prone source rocks have been demonstrated in Carboniferous, Triassic, and Jurassic rocks. Frequent registration of residual oil indicates that leakage, possibly related to young uplift might represent a risk factor. Successful exploration may be related to the understanding of the relation between the distribution of source rocks, their maturity and primary/secondary migration and young tectonic movement. Limited amounts of seismic and two to three wells have been drilled in the Kara Sea. In the Laptev and Eastern Siberian Sea farther to the east, no wells have been drilled and only limited seismic has been acquired.

  16. Mapping the Sea Floor of the Historic Area Remediation Site (HARS) Offshore of New York City

    USGS Publications Warehouse

    Butman, Bradford

    2002-01-01

    The area offshore of New York City has been used for the disposal of dredged material for over a century. The area has also been used for the disposal of other materials such as acid waste, industrial waste, municipal sewage sludge, cellar dirt, and wood. Between 1976 and 1995, the New York Bight Dredged Material Disposal Site, also known as the Mud Dump Site (MDS), received on average about 6 million cubic yards of dredged material annually. In September 1997 the MDS was closed as a disposal site, and it and the surrounding area were designated as the Historic Area Remediation Site (HARS). The sea floor of the HARS, approximately 9 square nautical miles in area, currently is being remediated by placing a minimum 1-m-thick cap of clean dredged material on top of the surficial sediments that are contaminated from previous disposal of dredged and other materials. The U.S. Geological Survey (USGS) is working cooperatively with the U.S. Army Corps of Engineers (USACE) to map the sea floor geology of the HARS and changes in the characteristics of the surficial sediments over time.

  17. Hydrodynamic trapping in the Cretaceous Nahr Umr lower sand of the North Area, Offshore Qatar

    SciTech Connect

    Wells, P.R.A.

    1988-03-01

    A hydrodynamic model is described to account for oil and gas occurrences in the Cretaceous of offshore Qatar, in the Arabian Gulf. Variable and inconsistent fluid levels and variable formation water potentials and salinities cannot be explained by combinations of stratigraphic and structural trapping. Indeed, there is no structural closure to the southwest of the oil and gas accumulations. The water-potential and salinity data and oil distribution are consistent with this model and indicate that a vigorous hydrodynamic system pervades the Cretaceous of the Arabian Gulf region. Extensive upward cross-formational discharge is taking place in the North Area. This cross-formation water flow could be partly responsible for localized leaching and reservoir enhancement in the chalky limestones.

  18. Local fatigue behavior in tapered areas of large offshore wind turbine blades

    NASA Astrophysics Data System (ADS)

    Aydin Raeis Hosseiny, Seyed; Jakobsen, Johnny

    2016-07-01

    Thickness transitions in load carrying elements lead to improved geometries and efficient material utilization. However, these transitions may introduce localized areas with high stress concentrations and may act as crack initiators that could potentially cause delamination and further catastrophic failure of an entire blade structure. The local strength degradation under an ultimate static loading, subsequent to several years of fatigue, is predicted for an offshore wind turbine blade. Fatigue failure indexes of different damage modes are calculated using a sub-modeling approach. Multi axial stresses are accounted for using a developed failure criterion with residual strengths instead of the virgin strengths. Damage initiation is predicted by including available Wohler curve data of E-Glass fabrics and epoxy matrix into multi-axial fatigue failure criteria. As a result of this study, proper knock-down factors for ply-drop effects in wind turbine blades under multi-axial static and fatigue loadings can be obtained.

  19. Forced folding and basement-detached normal faulting in the Haltenbanken area, offshore Norway

    SciTech Connect

    Withjack, M.O.; Meisling, K.E.; Russell, L.R.

    1988-02-01

    Triassic evaporites affected the structural development of the Haltenbanken area of offshore Norway during the Late Jurassic and Early Cretaceous by mechanically isolating Triassic and younger strata from older strata and basement. Many folds in the Haltenbanken area are forced folds above basement-involved normal faults. Forced folds formed, at least in part, because Triassic evaporites behaved ductilely, decoupling overlying strata from underlying faulted strata and basement. Seismic data show that these forced folds are asymmetric flexures that affect Lower Cretaceous, Jurassic, and Triassic strata. Strata beneath the Triassic evaporites are faulted. Some forced folds die out along strike into, and are cut by, basement-involved normal faults. Folding predominated above salt swells where decoupling was enhanced, whereas faulting occurred on the flanks of salt swells where salt thicknesses were reduced and decoupling was less effective. Many normal faults in the Haltenbanken area are basement-detached and flatten within the Triassic evaporites. Seismic data show that rollover anticlines and antithetic normal faults affect Lower Cretaceous, Jurassic, and Triassic strata within the hanging walls of these basement-detached normal faults. Strata beneath the evaporites are not affected by this deformation. Some basement-detached normal faults may be secondary structures associated with forced folding. Others, especially those with large displacements, may have formed in response to gravity sliding.

  20. Forced folding and basement-detached normal faulting in the Haltenbanken area, offshore Norway

    SciTech Connect

    Withjack, M.O.; Meisling, K.E.; Russell, L.R.

    1988-01-01

    Triassic evaporites affected the structural development of the Haltenbanken area of offshore Norway during the Late Jurassic and Early Cretaceous by mechanically isolating Triassic and younger strata from older strata and basement. Many folds in the Haltenbanken area are forced folds above basement-involved normal faults. Forced folds formed, at least in part, because Triassic evaporites behaved ductilely, decoupling overlying strata from underlying faulted strata and basement. Seismic data show that these forced folds are asymmetric flexures that affect Lower Cretaceous, Jurassic, and Triassic strata. Strata beneath the Traiassic evaporites are faulted. Some forced folds die out along strike into, and are cut by, basement-involved normal faults. Folding predominated above salt swells where decoupling was enhanced, whereas faulting occurred on the flanks of salt swells where salt thicknesses were reduced and decoupling was less effective. Many normal faults in the Haltenbanken area are basement-detached and flatten within the Triassic evaporites. Seismic data show that rollover anticlines and antithetic normal faults affect Lower Cretaceous, Jurassic, and Triassic strata within the hanging walls of these basement-detached normal faults. Strata beneath the evaporites are not affected by this deformation. Some basement-detached normal faults may be secondary structures associated with forced folding. Others, especially those with large displacements, may have formed in response to gravity sliding.

  1. Prey Fields and Habitat of Deep Diving Odontocetes: 3D Characterization and Modeling of Beaked and Sperm Whale Foraging Areas in the Tongue of the Ocean

    DTIC Science & Technology

    2012-09-30

    Characterization and Modeling of Beaked and Sperm Whale Foraging Areas in the Tongue of the Ocean Douglas P. Nowacek Associate Professor Duke...beaked and sperm whales ; ii) to measure and characterize the physics of these environments; iii) to assemble the characteristics measured (i) and... Sperm Whale Foraging Areas in the Tongue of the Ocean 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER

  2. Dynamically coupled 3D pollutant dispersion model for assessing produced water discharges in the Canadian offshore area.

    PubMed

    Zhao, Lin; Chen, Zhi; Lee, Kenneth

    2013-02-05

    Produced water is the contaminated water that is brought to the surface in the process of recovering oil and gas. On the basis of discharge volume, this type of contaminated water is the largest contributor to the offshore waste stream. Modeling studies of large amounts of wastewater discharge into offshore areas have helped in the understanding of pollutant dispersion behaviors in marine environments and in further evaluating the potential environmental effects resulting from produced water discharges. This study presents an integrated three-dimensional (3D) approach for the simulation of produced water discharges in offshore areas. Specifically, an explicit second-order finite difference method was used to model the far-field pollutant dispersion behavior, and this method was coupled with the jet-plume model JETLAG with an extension of the 3D cross-flow conditions to simulate the near-field mixing processes. A dynamic coupling technique with full consideration of the interaction between the discharged fluids and receiving waters was employed in the model. A case study was conducted on the Grand Banks of Newfoundland, Canada. The field validation of the modeling results was conducted for both the near-field and far-field dispersion processes, and the modeling results were in good agreement with the field observations. This study provides an integrated system tool for the simulation of complex transport processes in offshore areas, and the results from such modeling systems can be further used for the risk assessment analysis of the surface water environment.

  3. Optimization of a large integrated area development of gas fields offshore Sarawak, Malaysia

    SciTech Connect

    Inyang, S.E.; Tak, A.N.H.; Costello, G.

    1995-10-01

    Optimizations of field development plans are routine in the industry. The size, schedule and nature of the upstream gas supply project to the second Malaysia LNG (MLNG Dua) plant in Bintulu, Sarawak made the need for extensive optimizations critical to realizing a robust and cost effective development scheme, and makes the work of more general interest. The project comprises the upstream development of 11 offshore fields for gas supply to MLNG Dua plant at an initial plateau production of 7.8 million tons per year of LNG. The gas fields span a large geographical area in medium water depths (up to 440 ft), and contain gas reserves of a distinctly variable gas quality. This paper describes the project optimization efforts aimed to ensure an upstream gas supply system effectiveness of over 99% throughout the project life while maintaining high safety and environmental standards and also achieving an economic development in an era of low hydrocarbon prices. Fifty percent of the first of the three phases of this gas supply project has already been completed and the first gas from these fields is scheduled to be available by the end of 1995.

  4. [Pollution Characteristics of Perfluorinated Compounds in Offshore Marine Area of Shenzhen].

    PubMed

    Liu, Bao-lin; Zhang, Hong; Xie, Liu-wei; Liu, Guo-qing; Wang, Yan-ping; Wang, Xin-xuan; Li, Jing; Dong, Wei-hua

    2015-06-01

    In order to explore the pollution characteristics of perfluorinated compounds (PFCs), 10 surface seawaters and 7 surface sediments were collected in offshore marine area of Shenzhen (offshore distance >2 km) in September 2013. All the samples were prepared by solid-phase extraction and analyzed using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS). The results showed that 10 PFCs, including C4, C6 and C8 perfluorinated sulfonates (PFSAs) and C5-C11, perfluorinated carboxylic acids (PFCAs) were detected in the surface waters. ∑ PFC concentrations ranged from 1.74 ng x L(-1) to 14.7 ng x L(-1) with PFBS, PFOS and PFOA being the dominant compounds. The spatial distribution of ∑ PFC concentrations displayed the characteristic of "the west being higher than the east", with ∑ PFC concentrations of Lingding Sea and Shenzhen Bay being higher than those of Daya Bay and Dapeng Bay (P < 0.05). The farther the sampling location was from the shore, the lower the ∑ PFC concentrations were. Direct sewage emissions and rivers emptying into the sea might be the primary sources of PFCs in the surface seawaters. 8 PFCs, including C6 and C8 PFSAs and C5, C6, and C8-C11 PFCAs were detected in the surface sediments. ∑ PFC concentrations ranged from 2.22 micorg x kg(-1) to 2.62 microg x kg(-1) with PFOS being the dominant compounds. There was a small change of ∑ PFC concentrations in surface sediments, which might be contributed by the adsorption from overlying water. The adsorption of PFCs on sediment significantly increased with the increasing length of carbon chain, and the adsorption of PFSA was higher than that of PFCA with the same length of carbon chain as PFSA. Additionally, the comparison with other seawater PFC measurements showed high PFBS pollution in this study, whereas the level of PFOS in sediment was close to those of other studies.

  5. California State Waters Map Series: offshore of Tomales Point, California

    USGS Publications Warehouse

    Johnson, Samuel Y.; Dartnell, Peter; Golden, Nadine E.; Hartwell, Stephen R.; Greene, H. Gary; Erdey, Mercedes D.; Cochrane, Guy R.; Watt, Janet Tilden; Kvitek, Rikk G.; Manson, Michael W.; Endris, Charles A.; Dieter, Bryan E.; Krigsman, Lisa M.; Sliter, Ray W.; Lowe, Erik N.; Chinn, John L.; Johnson, Samuel Y.; Cochran, Susan A.

    2015-01-01

    Potential marine benthic habitats in the Offshore of Tomales Point map area range from unconsolidated continental-shelf sediment, to rocky continental-shelf substrate, to unconsolidated estuary sediments. Rocky-shelf outcrops and rubble are considered to be promising potential habitats for rockfish and lingcod, both of which are recreationally and commercially important species. Dynamic bedforms, such as the sand waves at the mouth of Tomales Bay, are considered potential foraging habitat for juvenile lingcod and possibly migratory fishes, as well as for forage fish such as Pacific sand lance.

  6. Foraging Parameters Influencing the Detection and Interpretation of Area-Restricted Search Behaviour in Marine Predators: A Case Study with the Masked Booby

    PubMed Central

    Sommerfeld, Julia; Kato, Akiko; Ropert-Coudert, Yan; Garthe, Stefan; Hindell, Mark A.

    2013-01-01

    Identification of Area-restricted search (ARS) behaviour is used to better understand foraging movements and strategies of marine predators. Track-based descriptive analyses are commonly used to detect ARS behaviour, but they may be biased by factors such as foraging trip duration or non-foraging behaviours (i.e. resting on the water). Using first-passage time analysis we tested if (I) daylight resting at the sea surface positions falsely increase the detection of ARS behaviour and (II) short foraging trips are less likely to include ARS behaviour in Masked Boobies Sula dactylatra. We further analysed whether ARS behaviour may be used as a proxy to identify important feeding areas. Depth-acceleration and GPS-loggers were simultaneously deployed on chick-rearing adults to obtain (1) location data every 4 minutes and (2) detailed foraging activity such as diving rates, time spent sitting on the water surface and in flight. In 82% of 50 foraging trips, birds adopted ARS behaviour. In 19.3% of 57 detected ARS zones, birds spent more than 70% of total ARS duration resting on the water, suggesting that these ARS zones were falsely detected. Based on generalized linear mixed models, the probability of detecting false ARS zones was 80%. False ARS zones mostly occurred during short trips in close proximity to the colony, with low or no diving activity. This demonstrates the need to account for resting on the water surface positions in marine animals when determining ARS behaviour based on foraging locations. Dive rates were positively correlated with trip duration and the probability of ARS behaviour increased with increasing number of dives, suggesting that the adoption of ARS behaviour in Masked Boobies is linked to enhanced foraging activity. We conclude that ARS behaviour may be used as a proxy to identify important feeding areas in this species. PMID:23717471

  7. Sound production patterns from humpback whales in a high latitude foraging area

    NASA Astrophysics Data System (ADS)

    Stimpert, Alison K.; Wiley, David N.; Barton, Kira L.; Johnson, Mark P.; Lammers, Marc O.; Au, Whitlow W. L.

    2005-09-01

    Numerous studies have been conducted on humpback whale song, but substantially fewer have focused on the acoustic properties of non-song sound production (i.e., feeding and social sounds). Non-invasive digital acoustic recording tags (DTAGS) were attached to humpback whales on the western North Atlantics Great South Channel feeding grounds during July 2004. Acoustic records totaling 48.4 data hours from four of these attachments were aurally analyzed for temporal trends in whale signal production. A custom automatic detection function was also used to identify occurrences of specific signals and evaluate their temporal consistency. Patterns in sound usage varied by stage of foraging dive and by time of day. Amount of time with signals present was greater at the bottom of dives than during surface periods, indicating that sounds are probably related to foraging at depth. For the two tags that recorded at night, signals were present during a greater proportion of daylight hours than night hours. These results will be compared with previously published trends describing diel patterns in male humpback whale song chorusing on the breeding grounds. Data from the continuation of this research during the summer of 2005 will also be included.

  8. Seismic constraints on Late Mesozoic magmatic plumbing system in the onshore-offshore area of Hong Kong

    NASA Astrophysics Data System (ADS)

    Xia, S.; Qiu, X.; Wan, K.

    2015-12-01

    We used active source wide-angle seismic data to determine a crustal structure beneath the onshore-offshore area of Hong Kong at the southern end of a broad belt dominated by Late Mesozoic intrusive and extrusive rocks in the coastal region of Southeast China. High-resolution tomographic images provide direct seismic evidence for the magmatic plumbing system of Late Mesozoic calderas. A localized high-velocity anomaly is revealed in the lower crust offshore between Hong Kong and Dangan Island, which may reflect basaltic underplating that induced voluminous silicic eruptions and granitoid plutons in the onshore-offshore area of Hong Kong. Tilted high-velocity zones are revealed in the entire crust beneath Dangan Island and the Late Mesozoic calderas of Hong Kong, which may reflect ascending magma chambers. We propose a paleo-Pacific plate subduction model to interpret our tomographic results and the generation of strong granitic magmatism in the Hong Kong area. Combining the tomographic image beneath the Lianhuashan Fault Zone with the distribution of Late Mesozoic calderas, we infer that the Lianhuashan Fault Zone might be the dominant magmatic conduit for mantle-derived magmas ascending to the upper crust. In addition, intersecting faults with different orientations could control the distribution and geometry of the vents, calderas, dykes and plutons and play an important role in forming magma conduits for individual volcanoes. Keywords: Basaltic underplating; Magmatic plumbing; Southeast China; Calderas; Active-source seismic tomography

  9. Seasonal patterns of prey availability and the foraging behavior of arctic foxes (Alopex lagopus) in a waterfowl nesting area

    USGS Publications Warehouse

    Stickney, Alice

    1991-01-01

    The foraging behavior of arctic foxes was observed in a waterfowl nesting area on the Yukon–Kuskokwim Delta of Alaska in 1985–1986. Observations were made during peak fox activity from two towers, 3 m high, located in different community types. Data were collected continuously for individual foxes on specific activities, the community in which activities occurred, and the type of food obtained. After migratory birds started nesting in the area, the food potentially available to foxes changed from microtines, old caches, and carrion to include eggs and birds. This change was reflected in the foraging behavior of the foxes as they switched to predation on eggs. After nesting began, the search success rate of foxes increased (from <30% to >50%) and search duration decreased (mean 19.7 s before nest initiation versus mean 9.4 s in mid-incubation) as the rate of food acquisition increased. Over 80% of the eggs taken by foxes were cached rather than eaten immediately, which extended the availability of this temporally limited resource to foxes. Eggs were the primary prey of arctic foxes during the nesting stages in both years, even though microtine populations were high in one year (1985) and low in the other (1986).

  10. Paleogeography and structure of the central Mediterranean: Sicily and its offshore area

    NASA Astrophysics Data System (ADS)

    Catalano, R.; Di Stefano, P.; Sulli, A.; Vitale, F. P.

    1996-08-01

    The geology of the mainland and offshore of Sicily is illustrated by a few geologic sections and seismic profiles across the late Cenozoic orogenic belt of central and western Sicily and across the Sardinia Channel and Sicily Straits. This belt is the result of several tectonic events. Deformation involved mainly the sedimentary cover of the old African continental margin characterized by a broad basinal domain, flanked along its external (southern) margin by a shallow-water carbonate platform attached to Africa in the Triassic. Compressional deformation started in the more internal basinal rock assemblages overlying a thinned crust. The most important structural characteristic of the early phase of thrusting is the duplex pile forming the bulk of the chain in Central Western Sicily. The structure consists of a basal allochthon, made up of Permian to Middle Triassic layers, an intermediate duplex wedge, composed of competent Mesozoic carbonates, and a roof complex, including Upper Mesozoic-Lower Tertiary less competent rocks. Large-scale clockwise rotation of the thrusts accompanied transpressional movements in the hinterland during the Pliocene. Right oblique reverse faults modified the previous tectonic contacts between the allochthons in the hinterland zones. Contemporaneous south-directed imbrications affected the southern external areas, progressively incorporating foreland and piggyback basins. Development of the Gela Thrust System appears to be linked to the transpressional event; its accretion is also related to contemporaneous underthrusting at deeper levels of Mesozoic carbonate substratum. The older buried thrust sheets were pushed up to the surface breaching the deformed Tertiary cover of the Gela TS. Northwards in the belt post-Messinian normal growth faults opened half graben whose sedimentary fill underwent structural inversion. Alternation of extension and compression tectonics characterizes the Sicilian continental margin in the last million years.

  11. Varying foraging patterns in response to competition? A multicolony approach in a generalist seabird.

    PubMed

    Corman, Anna-Marie; Mendel, Bettina; Voigt, Christian C; Garthe, Stefan

    2016-02-01

    Reducing resource competition is a crucial requirement for colonial seabirds to ensure adequate self- and chick-provisioning during breeding season. Spatial segregation is a common avoidance strategy among and within species from neighboring breeding colonies. We determined whether the foraging behaviors of incubating lesser black-backed gulls (Larus fuscus) differed between six colonies varying in size and distance to mainland, and whether any differences could be related to the foraging habitats visited. Seventy-nine incubating individuals from six study colonies along the German North Sea coast were equipped with GPS data loggers in multiple years. Dietary information was gained by sampling food pellets, and blood samples were taken for stable isotope analyses. Foraging patterns clearly differed among and within colonies. Foraging range increased with increasing colony size and decreased with increasing colony distance from the mainland, although the latter might be due to the inclusion of the only offshore colony. Gulls from larger colonies with consequently greater density-dependent competition were more likely to forage at land instead of at sea. The diets of the gulls from the colonies furthest from each other differed, while the diets from the other colonies overlapped with each other. The spatial segregation and dietary similarities suggest that lesser black-backed gulls foraged at different sites and utilized two main habitat types, although these were similar across foraging areas for all colonies except the single offshore island. The avoidance of intraspecific competition results in colony-specific foraging patterns, potentially causing more intensive utilization of terrestrial foraging sites, which may offer more predictable and easily available foraging compared with the marine environment.

  12. Quantifying offshore wind resources from satellite wind maps: study area the North Sea

    NASA Astrophysics Data System (ADS)

    Hasager, C. B.; Barthelmie, R. J.; Christiansen, M. B.; Nielsen, M.; Pryor, S. C.

    2006-01-01

    Offshore wind resources are quantified from satellite synthetic aperture radar (SAR) and satellite scatterometer observations at local and regional scale respectively at the Horns Rev site in Denmark. The method for wind resource estimation from satellite observations interfaces with the wind atlas analysis and application program (WAsP). An estimate of the wind resource at the new project site at Horns Rev is given based on satellite SAR observations. The comparison of offshore satellite scatterometer winds, global model data and in situ data shows good agreement. Furthermore, the wake effect of the Horns Rev wind farm is quantified from satellite SAR images and compared with state-of-the-art wake model results with good agreement. It is a unique method using satellite observations to quantify the spatial extent of the wake behind large offshore wind farms. Copyright

  13. Forage Budgeting

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pasture management in tropical agro-ecosystems is challenging because of unique soil, climate, and animal interactions. Budgeting forage as part of the grazing system can be difficult because of the strong seasonality of forage production and rapidly changing forage quality. Planning, measuring, and...

  14. Structure and present-day compression in the offshore area between Alicante and Ibiza Island (Eastern Iberian Margin)

    NASA Astrophysics Data System (ADS)

    Maillard, Agnès; Mauffret, Alain

    2013-04-01

    This study deals with the structure and recent deformation of the Eastern Iberian margin, extending from basement to seafloor and including the south-western margin of the Valencia Basin, the Alicante Shelf, the Ibiza Channel and its southern margin descending into the Algerian Basin. This area underwent a complex tectonic evolution linked to the back-arc opening of the North-western Mediterranean and the concomitant contraction of the Betic belt due to the collision with blocks located between Africa and Europe. This Oligo-Miocene structural heritage gave rise to a complex and continuous deformation through times including Late Miocene post-orogenic extension and Pliocene to Quaternary compression in the western Balearic area and coeval extension in the Valencia basin. This study presents maps of the depth to basement and Base of the Pliocene, as well as bathymetry data and seismic lines, which provide a precise integrated 3D study of the offshore domain. It reveals a major reactivation of the area, represented by the N80 to N60 trending structures, small discontinuous folds and thrusts in the Ibiza Channel and a large flexure on the Alicante shelf. The structures are picked out by erosion surfaces or deposits linked to the Messinian Salinity Crisis (MSC). These markers are ubiquitous in the seismic sedimentary sequences and record the lateral and vertical deformation active from the Messinian Salinity Crisis to the Present. The contraction in the western Iberian margin and concomitant extension in the southern Valencia Basin are consistent with the regional stress field as determined from the focal mechanisms of offshore earthquakes or recent GPS measurements. The tectonic compression of the studied area casts doubt on the eventual propagation of the present-day compressive stress from the Algerian margin to the Western Balearic Promontory.

  15. Modeling of oil mist and oil vapor concentration in the shale shaker area on offshore drilling installations.

    PubMed

    Bråtveit, Magne; Steinsvåg, Kjersti; Lie, Stein Atle; Moen, Bente E

    2009-11-01

    The objective of this study was to develop regression models to predict concentrations of oil mist and oil vapor in the workplace atmosphere in the shale shaker area of offshore drilling installations. Collection of monitoring reports of oil mist and oil vapor in the mud handling areas of offshore drilling installations was done during visits to eight oil companies and five drilling contractors. A questionnaire was sent to the rig owners requesting information about technical design of the shaker area. Linear mixed-effects models were developed using concentration of oil mist or oil vapor measured by stationary sampling as dependent variables, drilling installation as random effect, and potential determinants related to process technical parameters and technical design of the shale shaker area as fixed effects. The dataset comprised stationary measurements of oil mist (n = 464) and oil vapor (n = 462) from the period 1998 to 2004. The arithmetic mean concentrations of oil mist and oil vapor were 3.89 mg/m(3) and 39.7 mg/m(3), respectively. The air concentration models including significant determinants such as viscosity of base oil, mud temperature, well section, type of rig, localization of shaker, mechanical air supply, air grids in outer wall, air curtain in front of shakers, and season explained 35% and 17% of the total variance in oil vapor and oil mist, respectively. The developed models could be used to indicate what impact differences in technical design and changes in process parameters have on air concentrations of oil mist and oil vapor. Thus, the models will be helpful in planning control measures to reduce the potential for occupational exposure.

  16. New areas for HIPing of components for the offshore and demanding engineering industries

    SciTech Connect

    Hjorth, C.G.; Eriksson, H.

    1996-12-31

    During the recent years Powdermet Sweden has entered into major contracts to make HIP P/M Near Net Shapes for the Offshore Industry in the North Sea and elsewhere. With a fully integrated production facility including a Mega HIP vessel, cost for HIP`ed items are substantially reduced thus finding ready acceptance in other Engineering Industry. Due to Isotropy the mechanical properties are equal in all directions which is an other strength of the Technology. As a result of further developments at Powdermet in Capsule Fabrication it has been possible to reach closer to near net shape by the HIP technique. In fact in some cases the required machining of the HIP`ed Components is reduced to simple preparation of weld bevels and/or sealing faces. As a consequence of the HIP route the necessary welding in some cases is limited to one third of what is normal by conventional methods.

  17. Characterization of fibropapillomatosis in green turtles Chelonia mydas (Cheloniidae) captured in a foraging area in southeastern Brazil.

    PubMed

    Tagliolatto, Alícia Bertoloto; Guimarães, Suzana Machado; Lobo-Hajdu, Gisele; Monteiro-Neto, Cassiano

    2016-10-27

    Fibropapillomatosis (FP) is a multifactorial disease that affects all species of marine turtles, including green turtles Chelonia mydas (Linnaeus, 1758). It is characterised by the development of internal or external tumours that, depending on their locations and sizes, may intensely impact the health condition of sea turtles. The goal of this study was to characterise the disease in C. mydas found in a foraging area in southeastern Brazil, evaluate the prevalence in this region, and correlate presence and absence, size, body distribution, number of tumours, and disease severity with biometric variables of the captured green turtles. Between 2008 and 2014, the prevalence rate of FP was 43.09%, out of 246 green turtles. The size of the animals with FP was relatively greater than animals without tumours, and the prevalence of FP increased with animal size, peaking in the 60-80 cm size class. From 2013 to 2014, gross evaluation of fibropapillomas was performed. The number of tumours per turtle ranged from 1 to 158. The size of tumours ranged from <1 cm (Size A) to >10 cm (Size D); Size A tumours and turtles slightly affected by the disease (Score 1) predominated. Tumour progression (72.1%) and regression (32.8%) were seen in some recaptured individuals (n = 61). Moreover, 24.6% of these turtles showed both progressions and regressions of tumours.

  18. Fluid migration in the Eugene Island block 330 area, offshore Louisiana

    SciTech Connect

    Nunn, J.A. ); Roberts, S.J. ); Cathles, L.M. III ); Anderson, R.N. )

    1996-01-01

    In a study funded by industry and the Department of Energy, the Global Basins Research Network has imaged fluid flow pathways that charged shallow, hydropressured, Plio-Pleistocene reservoirs in the Eugene Island 330 field, offshore Louisiana. Hydrocarbons appear to be derived from turbidite stacks within the salt withdrawal mini-basin buried deep within the geopressured zone. Fault zones, with pore pressure dependent permeability, provide conduits for episodic expulsion of fluids out of the geopressured zone. Imaging of present day fluid migration was accomplished using multiple three-dimensional seismic surveys done several years apart. Volume processing and attribute analysis algorithms are used to identify seismic amplitude interconnectivity and changes over time that result from active fluid migration. Pressures and temperatures are used to provide rate and timing constraints. Geochemical variability in reservoirs is attributed to mixing of oils. Using detailed hydrostratigraphic information constructed from seismic and well data, we have simulated the episodic expulsion of fluids from the geopressured zone along faults into individual thin sand layers in the overlying hydropressured zone. Our finite element model, Akcess.Basin[trademark], realistically simulates fluid flow, heat and solute transport and pore pressure dependent permeability of faults and strata. Our results documenting the existence of past and present migration events connecting shallow reservoirs to deep source rocks implies that large, heretofore undiscovered hydrocarbon reserves exist deep within the geopressured zone along the deep water continental shelf of the northern Gulf of Mexico.

  19. Fluid migration in the Eugene Island block 330 area, offshore Louisiana

    SciTech Connect

    Nunn, J.A.; Roberts, S.J.; Cathles, L.M. III; Anderson, R.N.

    1996-12-31

    In a study funded by industry and the Department of Energy, the Global Basins Research Network has imaged fluid flow pathways that charged shallow, hydropressured, Plio-Pleistocene reservoirs in the Eugene Island 330 field, offshore Louisiana. Hydrocarbons appear to be derived from turbidite stacks within the salt withdrawal mini-basin buried deep within the geopressured zone. Fault zones, with pore pressure dependent permeability, provide conduits for episodic expulsion of fluids out of the geopressured zone. Imaging of present day fluid migration was accomplished using multiple three-dimensional seismic surveys done several years apart. Volume processing and attribute analysis algorithms are used to identify seismic amplitude interconnectivity and changes over time that result from active fluid migration. Pressures and temperatures are used to provide rate and timing constraints. Geochemical variability in reservoirs is attributed to mixing of oils. Using detailed hydrostratigraphic information constructed from seismic and well data, we have simulated the episodic expulsion of fluids from the geopressured zone along faults into individual thin sand layers in the overlying hydropressured zone. Our finite element model, Akcess.Basin{trademark}, realistically simulates fluid flow, heat and solute transport and pore pressure dependent permeability of faults and strata. Our results documenting the existence of past and present migration events connecting shallow reservoirs to deep source rocks implies that large, heretofore undiscovered hydrocarbon reserves exist deep within the geopressured zone along the deep water continental shelf of the northern Gulf of Mexico.

  20. Evolution and hydrocarbon potential of offshore Pinar Del Rio area, Southern Gulf of Mexico

    SciTech Connect

    Tenreyro-Perez, R.; Lopez-Rivera, J.G.; Fernandez-Carmona, J.; Lopez-Quintero, J.O.

    1996-09-01

    The evolution of Southeast Gulf of Mexico comprises three main periods: pre-orogenic, syn-orogenic and post-orogenic. During pre-orogenic time, from Lower Jurassic to Campanian, the stages are the rift of Pangaea and the thermal subsidence (or drift). In drift stage two domains interacted in the space; the carbonate platforms (Bahamas, Yucatan, Organos and others), and the deepwater basins. These fluctuations were dictated by the differential subsidence and horizontal displacements of basement blocks as well as by the eustatic movements of the ocean. The Organos platform, for example, was entirely drowned since Upper Jurassic and the sedimentation continued in deepwater environment. The collision between Great Antilles Volcanic Arc and the continental margins since Upper Cretaceous modeled the Cuban orogen. Here, the southern facies thrusted over the northern section with simultaneous strike-slip movements. The interaction suddenly ceased in Eocene. The source rock levels are considerably more frequent in the deepwater domain than in the platforms. The Lower and Upper Jurassic as well as Lower and Middle Cretaceous horizons contain very high levels of organic matter. The offshore seismic shows the transition from the thrusted belt to the foreland basin with a typical triangle zone configuration. Reservoirs are expected in the Cretaceous section covered by seals conformed by early foreland basin sediments of Upper Cretaceous-Paleocene age. Foothill structures has a great potential for hydrocarbon exploration.

  1. Walrus distributional and foraging response to changing ice and benthic conditions in the Chukchi Sea

    USGS Publications Warehouse

    Jay, Chadwick V.; Grebmeier, Jacqueline M.; Fischbach, Anthony S.

    2012-01-01

    Arctic species such as the Pacific walrus (Odobenus rosmarus divergens) are facing a rapidly changing environment. Walruses are benthic foragers and may shift their spatial patterns of foraging in response to changes in prey distribution. We used data from satellite radio-tags attached to walruses in 2009-2010 to map walrus foraging locations with concurrent sampling of benthic infauna to examine relationships between distributions of dominant walrus prey and spatial patterns of walrus foraging. Walrus foraging was concentrated offshore in the NE Chukchi Sea, and coastal areas of northwestern Alaska when sea ice was sparse. Walrus foraging areas in August-September were coincident with the biomass of two dominant bivalve taxa (Tellinidae and Nuculidae) and sipunculid worms. Walrusforaging costs associated with increased travel time to higher biomass food patches from land may be significantly higher than the costs from sea ice haul-outs and result in reduced energy storesin walruses. Identifying what resources are selected by walruses and how those resources are distributed in space and time will improve our ability to forecast how walruses might respond to a changing climate.

  2. Larviciding offshore islands reduces adulticidal treatment of populated areas adjacent to national wildlife refuges.

    PubMed

    Hribar, Lawrence J; Fussell, Edsel M; Leal, Andrea L

    2011-12-01

    The Florida Keys Mosquito Control District has conducted larvicide missions on uninhabited offshore islands of the Great White Heron National Wildlife Refuge and the National Key Deer Refuge since 2003. The objective of these missions is to reduce the need to apply adulticides on nearby populated islands where private lands are interspersed with refuge lands that support a diverse assemblage of native butterflies and insect-pollinated plants on Big Pine Key, No Name Key, Little Torch Key, Middle Torch Key, and Big Torch Key (the Torch Keys). More than 800 visits were made to refuge islands by Florida Keys Mosquito Control District personnel; 334 aerial larvicide missions were flown. From 2003 to 2010, a marked reduction in adult mosquito numbers was seen on Big Pine Key, and to a lesser extent on No Name Key. Seasonal distribution of mosquitoes was not different, however. Number of aerial adulticide missions flown on Big Pine Key, No Name Key, and the Torch Keys was 2, 1, and 2 in 2003; 9, 10, and 7 in 2004; 4, 4, and 2 in 2005; 6, 6, and 7 in 2006; 1, 0, and 0 in 2007; 3, 2, and 4 in 2008; 4, 3, and 4 in 2009; and 1, 1, and 3 in 2010, respectively. This is a dramatic reduction from prior years; from 1998 to 2002, 57 aerial adulticide missions were flown on Big Pine Key, 45 missions were flown on No Name Key, and 38 on the Torch Keys. Larviciding is an important component of an integrated approach to mosquito management that seeks to reduce environmental impacts on the national wildlife refuges.

  3. Dredging displaces bottlenose dolphins from an urbanised foraging patch.

    PubMed

    Pirotta, Enrico; Laesser, Barbara Eva; Hardaker, Andrea; Riddoch, Nicholas; Marcoux, Marianne; Lusseau, David

    2013-09-15

    The exponential growth of the human population and its increasing industrial development often involve large scale modifications of the environment. In the marine context, coastal urbanisation and harbour expansion to accommodate the rising levels of shipping and offshore energy exploitation require dredging to modify the shoreline and sea floor. While the consequences of dredging on invertebrates and fish are relatively well documented, no study has robustly tested the effects on large marine vertebrates. We monitored the attendance of common bottlenose dolphins (Tursiops truncatus) to a recently established urbanised foraging patch, Aberdeen harbour (Scotland), and modelled the effect of dredging operations on site usage. We found that higher intensities of dredging caused the dolphins to spend less time in the harbour, despite high baseline levels of disturbance and the importance of the area as a foraging patch.

  4. 50 CFR 216.191 - Designation of Offshore Biologically Important Marine Mammal Areas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Detailed information on the biology of marine mammals within the area, including estimated population size... Important Marine Mammal Areas. 216.191 Section 216.191 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE...

  5. 50 CFR 216.191 - Designation of Offshore Biologically Important Marine Mammal Areas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Detailed information on the biology of marine mammals within the area, including estimated population size... Important Marine Mammal Areas. 216.191 Section 216.191 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE...

  6. Offshore outlook: the American Arctic

    SciTech Connect

    Jahns, M.O.

    1985-05-01

    Offshore areas in the American Arctic are highlighted and the development of the area is compared with other offshore areas where the required technology is more readily available. Principal areas are shown in which new concepts are being put to practice. Canada's east coast is examined. Several technological trends are reviewed to help operators accelerate the discovery and development of arctic petroleum reserves.

  7. [Effects of riparian ecological restoration engineering with offshore wave-elimination weir on restoration area's water quality].

    PubMed

    Tang, Hao; Zhang, Hui; Xie, Fei; Xu, Chi; Wang, Lei; Liu, Mao-Song

    2012-06-01

    Riparian ecological restoration engineering with offshore wave-elimination weir is an engineering measure with piled wave-elimination weir some meters away from the shore. This measure can dissipate waves, promote sediment deposition, and create an artificial semi-closed bay to restore vegetation in a riparian area which has hard dam and destroyed vegetation. Three habitat gradient zones, i. e., emerged vegetation zone, submerged vegetation zone, and open water area, can be formed after this engineering. In June 2010-May 2011, a field investigation was conducted on the water quality in the three zones in an ecological restoration area of Gonghu Bay, Taihu Lake. The water body inside the weir generally had lower concentrations of nitrite and nitrate but higher concentrations of ammonium and total nitrogen than the water body outside the weir. The water phosphorus concentration inside the weir was lower than that outside the weir in autumn and winter, while an opposite trend was observed in spring and summer. The coefficients of variation of the water body' s nitrite and orthophosphate concentration inside the weir decreased, and the annual maximum values of the water nitrite, nitrate, and orthophosphate concentrations inside the weir were lower than those outside the weir. On the contrary, the coefficients of variation of the water body's ammonium and total nitrogen concentrations inside the weir increased, and the annual maximum values of the water ammonium and total nitrogen concentrations inside the weir were higher than those outside the weir. To some extent, the restoration engineering could exacerbate the deterioration of the water quality indices such as ammonium and total nitrogen in the restoration area by the end of growth season

  8. Quantifying Fish Assemblages in Large, Offshore Marine Protected Areas: An Australian Case Study

    PubMed Central

    Hill, Nicole A.; Barrett, Neville; Lawrence, Emma; Hulls, Justin; Dambacher, Jeffrey M.; Nichol, Scott; Williams, Alan; Hayes, Keith R.

    2014-01-01

    As the number of marine protected areas (MPAs) increases globally, so does the need to assess if MPAs are meeting their management goals. Integral to this assessment is usually a long-term biological monitoring program, which can be difficult to develop for large and remote areas that have little available fine-scale habitat and biological data. This is the situation for many MPAs within the newly declared Australian Commonwealth Marine Reserve (CMR) network which covers approximately 3.1 million km2 of continental shelf, slope, and abyssal habitat, much of which is remote and difficult to access. A detailed inventory of the species, types of assemblages present and their spatial distribution within individual MPAs is required prior to developing monitoring programs to measure the impact of management strategies. Here we use a spatially-balanced survey design and non-extractive baited video observations to quantitatively document the fish assemblages within the continental shelf area (a multiple use zone, IUCN VI) of the Flinders Marine Reserve, within the Southeast marine region. We identified distinct demersal fish assemblages, quantified assemblage relationships with environmental gradients (primarily depth and habitat type), and described their spatial distribution across a variety of reef and sediment habitats. Baited videos recorded a range of species from multiple trophic levels, including species of commercial and recreational interest. The majority of species, whilst found commonly along the southern or south-eastern coasts of Australia, are endemic to Australia, highlighting the global significance of this region. Species richness was greater on habitats containing some reef and declined with increasing depth. The trophic breath of species in assemblages was also greater in shallow waters. We discuss the utility of our approach for establishing inventories when little prior knowledge is available and how such an approach may inform future monitoring

  9. Metals in water, sediments, and biota of an offshore oil exploration area in the Potiguar Basin, Northeastern Brazil.

    PubMed

    Lacerda, L D; Campos, R C; Santelli, R E

    2013-05-01

    Metal concentrations were evaluated in water, bottom sediments, and biota in four field campaigns from 2002 to 2004 in the Potiguar Basin, northeastern Brazil, where offshore oil exploration occurs. Analyses were performed by inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry. Total metal concentrations in water (dissolved + particulate) and sediments were in the range expected for coastal and oceanic areas. Abnormally high concentrations in waters were only found for Ba (80 μg l(-1)) and Mn (12 μg l(-1)) at the releasing point of one of the outfalls, and for the other metals, concentrations in water were found in stations closer to shore, suggesting continental inputs. In bottom sediments, only Fe and Mn showed abnormal concentrations closer to the effluent releasing point. Metal spatial distribution in shelf sediments showed the influence of the silt-clay fraction distribution, with deeper stations at the edge of the continental shelf, which are much richer in silt-clay fraction showing higher concentrations than shallower sediments typically dominated by carbonates. Metal concentrations in estuarine (mollusks and crustaceans) and marine (fish) organisms showed highest concentrations in oysters (Crassostrea rhizophorae). Fish tissues metal concentrations were similar between the continental shelf influenced by the oil exploration area and a control site. The results were within the range of concentrations reported for pristine environments without metals contamination. The global results suggest small, if any, alteration in metal concentrations due to the oil exploration activity in the Potiguar Basin. For monitoring purposes, the continental inputs and the distribution of the clay-silt fraction need to be taken into consideration for interpreting environmental monitoring results.

  10. Spatial memory in foraging games.

    PubMed

    Kerster, Bryan E; Rhodes, Theo; Kello, Christopher T

    2016-03-01

    Foraging and foraging-like processes are found in spatial navigation, memory, visual search, and many other search functions in human cognition and behavior. Foraging is commonly theorized using either random or correlated movements based on Lévy walks, or a series of decisions to remain or leave proximal areas known as "patches". Neither class of model makes use of spatial memory, but search performance may be enhanced when information about searched and unsearched locations is encoded. A video game was developed to test the role of human spatial memory in a canonical foraging task. Analyses of search trajectories from over 2000 human players yielded evidence that foraging movements were inherently clustered, and that clustering was facilitated by spatial memory cues and influenced by memory for spatial locations of targets found. A simple foraging model is presented in which spatial memory is used to integrate aspects of Lévy-based and patch-based foraging theories to perform a kind of area-restricted search, and thereby enhance performance as search unfolds. Using only two free parameters, the model accounts for a variety of findings that individually support competing theories, but together they argue for the integration of spatial memory into theories of foraging.

  11. Sympatric cattle grazing and desert bighorn sheep foraging

    USGS Publications Warehouse

    Garrison, Kyle R.; Cain, James W.; Rominger, Eric M.; Goldstein, Elise J.

    2015-01-01

    Foraging behavior affects animal fitness and is largely dictated by the resources available to an animal. Understanding factors that affect forage resources is important for conservation and management of wildlife. Cattle sympatry is proposed to limit desert bighorn population performance, but few studies have quantified the effect of cattle foraging on bighorn forage resources or foraging behavior by desert bighorn. We estimated forage biomass for desert bighorn sheep in 2 mountain ranges: the cattle-grazed Caballo Mountains and the ungrazed San Andres Mountains, New Mexico. We recorded foraging bout efficiency of adult females by recording feeding time/step while foraging, and activity budgets of 3 age-sex classes (i.e., adult males, adult females, yearlings). We also estimated forage biomass at sites where bighorn were observed foraging. We expected lower forage biomass in the cattle-grazed Caballo range than in the ungrazed San Andres range and lower biomass at cattle-accessible versus inaccessible areas within the Caballo range. We predicted bighorn would be less efficient foragers in the Caballo range. Groundcover forage biomass was low in both ranges throughout the study (Jun 2012–Nov 2013). Browse biomass, however, was 4.7 times lower in the Caballo range versus the San Andres range. Bighorn in the Caballo range exhibited greater overall daily travel time, presumably to locate areas of higher forage abundance. By selecting areas with greater forage abundance, adult females in the Caballo range exhibited foraging bout efficiency similar to their San Andres counterparts but lower overall daily browsing time. We did not find a significant reduction in forage biomass at cattle-accessible areas in the Caballo range. Only the most rugged areas in the Caballo range had abundant forage, potentially a result of intensive historical livestock use in less rugged areas. Forage conditions in the Caballo range apparently force bighorn to increase foraging effort by

  12. The Role of Sequence Stratigraphic Analysis in the Messinian crisis at Baltim Area, Off-Shore Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El-Deen Badawy, A. M.; Abu El-Ata, A. S.; El-Gendy, N. H.

    2013-12-01

    The Egyptian Nile Delta has recognized over the different human civilizations, as the source of life/ basket of wheat. In the recent time, the Nile Delta revealed another hidden treasure that hidden below the Mediterranean Sea within its sediments. This treasure reflects a number of giant gas reservoirs that require only the suitable technology and the assured ideas to commence injecting gas into the industrial veins of the growing Egyptian economy. The current study is aiming to discuss the Messinian Prospectivity of the concerned area, which is located in the offshore of the Nile Delta, about 25 Km from the Mediterranean Sea shoreline. An integrated exploration approach applied for a selected area, using a variety of subsurface borehole geologic and log data of the selected wells distributed in the study area, as well as biostratigraphic data. The well data comprise well markers, and electric logs (e.g. gamma ray, density, neutron and sonic logs), where the geological data represented by litho-stratigraphic information, as well as ditch samples analysis of the studied interval. Biostratigraphic data include biozones, benthonic to planktonic ratios, nannofossils and foraminiferal data. Different methods and techniques were applied by using different softwares such as Petrel and Interactive petrophysical software. Four missing times were identified intra-Pleistocene, Late Pliocene, Late Pliocene-Early Pliocene and Messinian. It has concluded that, the depositional environments ranged from shallow marine to middle nerritic and may reach upper bathyal toward the northern part of the study area. The top of Abu Madi Formation dated with the calcareous nannofossils zone NN12a, while the base dated with NN11c, and its age varied from 5.2 Ma to 5.7 Ma. The maximum flooding surface is dated with the calcareous nannofossils zone NN13 and the planktonic foraminiferal zone SN18 at 5 Ma (the acme presence of the Sphaeroidinellopsis sp.). From the utility of wireline logs for

  13. Sequence Stratigraphic Analysis for Delineating the Sedimentation Characteristic and Modeling of Nidoco Area, Off-Shore Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El Deen, Ahmed; Abu El-Ata, Ahmed; El-Gendy, Nader

    2014-05-01

    The Egyptian Nile Delta has recognized over the different human civilizations, as the source of life/ basket of wheat. In the recent time, the Nile Delta revealed another hidden treasure that hidden below the Mediterranean Sea within its sediments. This treasure reflects a number of giant gas reservoirs that require only the suitable technology and the assured ideas to commence injecting gas into the industrial veins of the growing Egyptian economy. The current study is aiming to discuss the Messinian Prospectivity of the concerned area, which is located in the offshore of the Nile Delta, about 25 Km from the Mediterranean Sea shoreline. An integrated exploration approach applied for a selected area, using a variety of subsurface borehole geologic and log data of the selected wells distributed in the study area, as well as biostratigraphic data. The well data comprise well markers, and electric logs (e.g. gamma ray, density, neutron and sonic logs), where the geological data represented by litho-stratigraphic information, as well as ditch samples analysis of the studied interval. Biostratigraphic data include biozones, benthonic to planktonic ratios, nannofossils and foraminiferal data. Different methods and techniques were applied by using different softwares such as Petrel and Interactive petrophysical software. Four missing times were identified intra-Pleistocene, Late Pliocene, Late Pliocene-Early Pliocene and Messinian. It has concluded that, the depositional environments ranged from shallow marine to middle nerritic and may reach upper bathyal toward the northern part of the study area. The top of Abu Madi Formation dated with the calcareous nannofossils zone NN12a, while the base dated with NN11c, and its age varied from 5.2 Ma to 5.7 Ma. The maximum flooding surface is dated with the calcareous nannofossils zone NN13 and the planktonic foraminiferal zone SN18 at 5 Ma (the acme presence of the Sphaeroidinellopsis sp.). From the utility of wireline logs for

  14. Offshore Wind Research (Fact Sheet)

    SciTech Connect

    Not Available

    2011-10-01

    This 2-page fact sheet describes NREL's offshore wind research and development efforts and capabilities. The National Renewable Energy Laboratory is internationally recognized for offshore wind energy research and development (R&D). Its experience and capabilities cover a wide spectrum of wind energy disciplines. NREL's offshore wind R&D efforts focus on critical areas that address the long-term needs of the offshore wind energy industry and the Department of Energy (DOE). R&D efforts include: (1) Developing offshore design tools and methods; (2) Collaborating with international partners; (3) Testing offshore systems and developing standards; (4) Conducting economic analyses; (5) Characterizing offshore wind resources; and (6) Identifying and mitigating offshore wind grid integration challenges and barriers. NREL has developed and maintains a robust, open-source, modular computer-aided engineering (CAE) tool, known as FAST. FAST's state-of-the-art capabilities provide full dynamic system simulation for a range of offshore wind systems. It models the coupled aerodynamic, hydrodynamic, control system, and structural response of offshore wind systems to support the development of innovative wind technologies that are reliable and cost effective. FAST also provides dynamic models of wind turbines on offshore fixed-bottom systems for shallow and transitional depths and floating-platform systems in deep water, thus enabling design innovation and risk reduction and facilitating higher performance designs that will meet DOE's cost of energy, reliability, and deployment objectives.

  15. Methane Release and Pingo-Like Feature Across the South kara Sea Shels, an Area of Thawing Offshore Permafrost

    NASA Astrophysics Data System (ADS)

    Serov, P.; Portnov, A.; Mienert, J.

    2015-12-01

    Thawing subsea permafrost controls methane release from the Russian Arctic shelf having a considerable impact on the climate-sensitive Arctic environment. Our recent studies revealed extensive gas release over an area of at least 7500 km2and presence of pingo-like features (PLFs), showing severe methane leakage, in the South Kara Sea in water depths >20m (Serov et al., 2015). Specifically, we detected shallow methane ebullition sites expressed in water column acoustic anomalies (gas flares and gas fronts) and areas of increased dissolved methane concentrations in bottom water, which might be sufficient sources of carbon for seawater-atmosphere exchange. A study of nature and source of leaking gas was focused on two PLFs, which are acoustically transparent circular mounds towering 5-9 m above the surrounding seafloor. One PLF (PLF 2) connects to biogenic gas from deeper sources, which is reflected in δ13CCH4 values ranging from -55,1‰ to -88,0‰ and δDCH4values varied from -175‰ to -246‰. Low organic matter content (0.52-1.69%) of seafloor sediments restricts extensive in situ methane production. The formation of PLF 2 is directly linked to the thawing of subsea permafrost and, possibly, decomposition of permafrost related gas hydrates. High accumulations of biogenic methane create the necessary forces to push the remaining frozen layers upwards and, therefore, form a topographic feature. We speculate that PLF 1, which shows ubiquitously low methane concentrations, is either a relict submerged terrestrial pingo, or a PLF lacking the necessary underlying methane accumulations. Our model of glacial-interglacial permafrost evolution supports a scenario in which subsea permafrost tapers seaward and pinches out at 20m isobaths, controlling observed methane emissions and development of PLFs. Serov. P., A. Portnov, J. Mienert, P. Semenov, and P. Ilatovskaya (2015), Methane release from pingo-like features across the South Kara Sea shelf, an area of thawnig

  16. Effects of artificial illumination on the nocturnal foraging of waders

    NASA Astrophysics Data System (ADS)

    Santos, Carlos D.; Miranda, Ana C.; Granadeiro, José P.; Lourenço, Pedro M.; Saraiva, Sara; Palmeirim, Jorge M.

    2010-03-01

    Large areas of natural and semi-natural habitats are exposed to artificial illumination from adjacent urban areas and roads. Estuarine and coastal wetlands are particularly exposed to such illumination because shorelines often are heavily utilized by man. However, the impact of artificial illumination on the waders that forage in these highly productive habitats is virtually unknown. We evaluated the effects of artificial illumination on the nocturnal habitat selection and foraging behaviour of six wader species with different feeding strategies: three visual foragers, two species that alternate visual and tactile strategies (mixed foragers), and one tactile forager. We quantified the number of birds and their foraging behaviour at sites affected and not affected by streetlights, and also before and after illuminating experimental sites. Areas illuminated by streetlights were used more during the night by visual foragers, and to a lesser extent by mixed foragers, than non-illuminated areas. Visual foragers increased their foraging effort in illuminated areas, and mixed foragers changed to more efficient visual foraging strategies. These behavioural shifts improved prey intake rate by an average of 83% in visual and mixed foragers. We have showed that artificial illumination has a positive effect on the nocturnal foraging of waders, but on the other hand may draw them to degraded areas close to urban centres, and potentially raises their exposure to predators. Our findings suggest that artificial illumination is worth investigation as a tool in the management of intertidal habitats for waders.

  17. Movements and foraging effort of Steller's Eiders and Harlequin Ducks wintering near Dutch Harbor, Alaska

    USGS Publications Warehouse

    Reed, J.A.; Flint, P.L.

    2007-01-01

    We studied the movements and foraging effort of radio-marked Steller's Eiders (Polysticta stelleri) and Harlequin Ducks (Histrionicus histrionicus) to evaluate habitat quality in an area impacted by industrial activity near Dutch Harbor, Alaska. Foraging effort was relatively low, with Steller's Eiders foraging only 2.7 ± 0.6 (SE) hours per day and Harlequin Ducks 4.1 ± 0.5 hours per day. Low-foraging effort during periods of high-energetic demand generally suggests high food availability, and high food availability frequently corresponds with reductions in home range size. However, the winter ranges of Harlequin Ducks did not appear to be smaller than usual, with the mean range size in our study (5.5 ± 1.1 km2) similar to that reported by previous investigators. The mean size of the winter ranges of Steller's Eiders was similar (5.1 ± 1.3 km2), but no comparable estimates are available. Eutrophication of the waters near Dutch Harbor caused by seafood processing and municipal sewage effluent may have increased populations of the invertebrate prey of these sea ducks and contributed to their low-foraging effort. The threat of predation by Bald Eagles (Haliaeetus leucocephalus) that winter near Dutch Harbor may cause Steller's Eiders and Harlequin Ducks to move further offshore when not foraging, contributing to an increase in range sizes. Thus, the movement patterns and foraging behavior of these ducks likely represent a balance between the cost and benefits of wintering in a human-influenced environment.

  18. Reorganization of a marine trophic network along an inshore-offshore gradient due to stronger pelagic-benthic coupling in coastal areas

    NASA Astrophysics Data System (ADS)

    Kopp, Dorothée; Lefebvre, Sébastien; Cachera, Marie; Villanueva, Maria Ching; Ernande, Bruno

    2015-01-01

    Recent theoretical considerations have highlighted the importance of the pelagic-benthic coupling in marine food webs. In continental shelf seas, it was hypothesized that the trophic network structure may change along an inshore-offshore gradient due to weakening of the pelagic-benthic coupling from coastal to offshore areas. We tested this assumption empirically using the eastern English Channel (EEC) as a case study. We sampled organisms from particulate organic matter to predatory fishes and used baseline-corrected carbon and nitrogen stable isotope ratios (δ13C and δ15N) to determine their trophic position. First, hierarchical clustering on δ13C and δ15N coupled to bootstrapping and estimates of the relative contribution of pelagic and benthic carbon sources to consumers' diet showed that, at mesoscale, the EEC food web forms a continuum of four trophic levels with trophic groups spread across a pelagic and a benthic trophic pathway. Second, based on the same methods, a discrete approach examined changes in the local food web structure across three depth strata in order to investigate the inshore-offshore gradient. It showed stronger pelagic-benthic coupling in shallow coastal areas mostly due to a reorganization of the upper consumers relative to the two trophic pathways, benthic carbon sources being available to pelagic consumers and, reciprocally, pelagic sources becoming accessible to benthic species. Third a continuous approach examined changes in the mean and variance of upper consumers' δ13C and δ15N with depth. It detected a significant decrease in δ13C variance and a significant increase in δ15N variance as depth increases. A theoretical two-source mixing model showed that an inshore-offshore decrease in the pelagic-benthic coupling was a sufficient condition to produce the δ13C variance pattern, thus supporting the conclusions of the discrete approach. These results suggest that environmental gradients such as the inshore-offshore one should

  19. Offshore medicine.

    PubMed

    Baker, D

    2001-03-01

    Offshore life can be refreshing for medics who are looking for a little change of pace; however, it is not for everyone. Working offshore can be the easiest or most boring job you'll ever have. It takes a specific type of medic to fit this mold. So, if you are considering a career in the offshore field, take all of the above into consideration. You are not just making a change in jobs, but a change in lifestyle. Once you become accustomed to this lifestyle, it will be hard to go back to the everyday hustle and bustle of the streets. For more information about working offshore, contact Acadian Contract Services at 800/259-333, or visit www.acadian.com.

  20. Foraging pattern, colony distribution, and foraging range of the Florida harvester ant Pogonomyrmex badius

    SciTech Connect

    Harrison, J.S.; Gentry, J.B.

    1981-12-01

    This report describes the foraging pattern of the Florida harvester ant Pogonomyrmex badius in a high-density population of colonies. The foraging pattern has both promoted and been influenced by the colony distribution. Pogonomyrmex badius forages from short trails which extend into a surrounding foraging range. Direction of foraging trails is influenced by the location of a colony's near neighbors. Seasonal nest relocations always occur along a foraging trail, usually the main trail. Foraging ranges are not actively defended, but are used almost exclusively by foragers from a single colony. Foraging ranges will be extended into an area abondoned by neighboring foragers, indicating that forager presence may define each colony's range. Colony distribution has remained essentially the same for several years, despite seasonal nest relocations and addition of new colonies. Establishment of trails and exclusive foraging ranges by each colony minimizes encounters with neighboring foragers and guarantees access to available resources; this pattern also pomotes maintenance of the existing colony distribution and partitioning of resources.

  1. Foraging pattern, colony distribution, and foraging range of the Florida harvester ant, Pogonomyrmex badius

    SciTech Connect

    Harrison, J.S.; Gentry, J.B.; Aiken, S.C.

    1981-12-01

    This report describes the foraging pattern of the Florida harvester ant Pogonomyrmex badius in a high-density population of colonies. The foraging pattern has both promoted and been influenced by the colony distribution. Pogonomyrmex badius forages from short trails which extend into a surrounding foraging range. Direction of foraging trails is influenced by the location of a colony's near neighbors. Seasonal nest relocations always occur along a foraging trail, usually the main trail. Foraging ranges are not actively defended, but are used almost exclusively by foragers from a single colony. Foraging ranges will be extended into an area abandoned by neighboring foragers, indicating that forager presence may define each colony's range. Colony distribution has remained essentially the same for several years, despite seasonal nest relocations and addition of new colonies. Establishment of trails and exclusive foraging ranges by each colony minimizes encounters with neighboring foragers and guarantees access to available resources; this pattern also promotes maintenance of the existing colony distribution and partitioning of resources.

  2. Habitat use and foraging patterns of molting male Long-tailed Ducks in lagoons of the central Beaufort Sea, Alaska

    USGS Publications Warehouse

    Flint, Paul L.; Reed, John; Deborah Lacroix,; Richard Lanctot,

    2016-01-01

    From mid-July through September, 10 000 to 30 000 Long-tailed Ducks (Clangula hyemalis) use the lagoon systems of the central Beaufort Sea for remigial molt. Little is known about their foraging behavior and patterns of habitat use during this flightless period. We used radio transmitters to track male Long-tailed Ducks through the molt period from 2000 to 2002 in three lagoons: one adjacent to industrial oil field development and activity and two in areas without industrial activity. We found that an index to time spent foraging generally increased through the molt period. Foraging, habitat use, and home range size showed similar patterns, but those patterns were highly variable among lagoons and across years. Even with continuous daylight during the study period, birds tended to use offshore areas during the day for feeding and roosted in protected nearshore waters at night. We suspect that variability in behaviors associated with foraging, habitat use, and home range size are likely influenced by availability of invertebrate prey. Proximity to oil field activity did not appear to affect foraging behaviors of molting Long-tailed Ducks.

  3. Terrestrial and Marine Foraging Strategies of an Opportunistic Seabird Species Breeding in the Wadden Sea.

    PubMed

    Garthe, Stefan; Schwemmer, Philipp; Paiva, Vitor H; Corman, Anna-Marie; Fock, Heino O; Voigt, Christian C; Adler, Sven

    2016-01-01

    Lesser black-backed gulls Larus fuscus are considered to be mainly pelagic. We assessed the importance of different landscape elements (open sea, tidal flats and inland) by comparing marine and terrestrial foraging behaviours in lesser black-backed gulls breeding along the coast of the southern North Sea. We attached GPS data loggers to eight incubating birds and collected information on diet and habitat use. The loggers recorded data for 10-19 days to allow flight-path reconstruction. Lesser black-backed gulls foraged in both offshore and inland areas, but rarely on tidal flats. Targets and directions were similar among all eight individuals. Foraging trips (n = 108) lasted 0.5-26.4 h (mean 8.7 h), and ranges varied from 3.0-79.9 km (mean 30.9 km). The total distance travelled per foraging trip ranged from 7.5-333.6 km (mean 97.9 km). Trips out to sea were significantly more variable in all parameters than inland trips. Presence in inland areas was closely associated with daylight, whereas trips to sea occurred at day and night, but mostly at night. The most common items in pellets were grass (48%), insects (38%), fish (28%), litter (26%) and earthworms (20%). There was a significant relationship between the carbon and nitrogen isotope signals in blood and the proportional time each individual spent foraging at sea/land. On land, gulls preferentially foraged on bare ground, with significantly higher use of potato fields and significantly less use of grassland. The flight patterns of lesser black-backed gulls at sea overlapped with fishing-vessel distribution, including small beam trawlers fishing for shrimps in coastal waters close to the colony and large beam-trawlers fishing for flatfish at greater distances. Our data show that individuals made intensive use of the anthropogenic landscape and seascape, indicating that lesser black-backed gulls are not a predominantly marine species during the incubation period.

  4. Overlap in offshore habitat use by double-crested cormorants and boaters in western Lake Erie

    USGS Publications Warehouse

    Stapanian, Martin A.; Bur, Michael T.

    2002-01-01

    Double-crested cormorants (Phalacrocorax auritus) and boats of 2 length classes (≤ 8 m and > 8 m) were counted from a boat along 31 established strip transects in western Lake Erie from 24 April to 1 September 2000. Each transect included only one of the following habitats: (1) offshore of a breeding island or roosting/loafing area for cormorants (“refuge”), (2) reefs or shoals, (3) open water, or (4) offshore of an island shoreline that had evidence of development by humans. Foraging cormorants were recorded most often offshore of refuges and least often on open water. There was no difference between the numbers of foraging cormorants/km2 recorded offshore of developed shorelines and on reefs and shoals. More than half of all boats recorded were on transects that were within 1 km of developed shorelines. Among those transects > 1 km from developed shorelines, there were no differences among the habitats for the number of boats of either length class. The respective ranks of the 31 transect means of the numbers of cormorants/km2 and the numbers of boats/km2 in either length class were uncorrelated. The results suggest that (1) cormorants select foraging habitats based mainly on shoreline type, distance from shoreline, and depth, and (2) the amount of boat traffic is influenced by proximity to port and trip objectives, including sport angling and recreational boating. Although there is overlap in habitat use by cormorants and humans, this overlap is not complete. The perception of cormorants as a threat to fish populations may in part be due to this overlap.

  5. Characterization of H/V Spectral Ratios for the Assessment of Slope Stability in the Gas Hydrate-rich Area: an Example from Offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, J. Y.; Tsia, C. H.; Cheng, W. B.; Chin, S. J.; Lin, S. S.; Liang, C. W.

    2015-12-01

    The Nakamura's method, which calculates the ratios between horizontal and vertical component spectra of seismic signals (H/V), is widely used in the inland area. However, few related estimations were performed for the offshore area and little knowledge for the marine sediments were obtained. From 2013 to 2015, three passive ocean bottom seismometer (OBS) experiments were conducted in gas hydrate-rich area offshore SW Taiwan in the aim of acquiring information related to the physical properties of seafloor sediments. The H/V of the seafloor sediments in the three areas were estimated by using the ambient noise and seismic signal recorded by OBSs. The resonance frequency of each site was estimated from the main peak of H/V distribution and a range between 5 and 10 Hz were obtained. Based on the empirical law, this resonance frequency range should correspond to a sediment thickness of approximately several to ten of meters. This estimation is consistent with the thickness of the sedimentary cover imaged by chirp sonar survey, suggesting that the site response of seafloor is dominantly controlled by the unconsolidated sedimentary layer on the top of the sea bed. Remarkably, the H/V ratios obtained in our study area are much larger than that calculated for the inland areas. The magnification can reach as high as 50 to more than 100. This observation infers that the sea water movement might emphasize the horizontal motion of the marine sediments, which is crucial for the slope stability assessment. Moreover, for most stations located in the active margin, no distinct peak is observed for the H/V pattern calculated during earthquakes. However, in the passive margin, the H/V peak calculated from ambient noise and earthquakes is mostly identical. This phenomenon may suggest that relatively unclear sedimentary boundary exist in the active margin environment. Estimating H/V spectral ratios of data recorded by the OBSs deployed in the southwest Taiwan offshore area offers a

  6. Depot fatty acid composition in immature green turtles (Chelonia mydas) residing at two near-shore foraging areas in the Hawaiian Islands.

    PubMed

    Seaborn, Gloria T; Katherine Moore, M; Balazs, George H

    2005-02-01

    The lipid content and fatty acid composition of depot fat were determined for 58 immature green turtles (Chelonia mydas) residing at two near-shore foraging areas, Ahu-O-Laka, located in Kaneohe Bay on Oahu, and Kiholo Bay located on the island of Hawaii. Benthic flora at Kiholo was limited to a single algal species but included algae and seagrass at Ahu-O-Laka. Turtle straight carapace length ranged from 38.6 to 59.2 cm, suggesting that the sample set included new recruits to up to 12-year residents. Fatty acid data were analyzed using principal components analysis (PCA). PC1 accounted for over 50% of the variance. Turtles were generally delineated along PC1 by the length of time on benthic foraging grounds, with high (>0.75) negative loadings for the fatty acids 22:6n-3, 7M7H, t16:1n-10, 15:0, and 17:0 associated with relatively new recruits (suggesting a pelagic dietary source for these fatty acids) and high positive loadings for 12:0 and 14:0 associated with long-term residents. PC2 separated turtles primarily by capture location, with high positive loadings for 18:2n-6 and 18:3n-3 [the primary seagrass polyunsaturated fatty acids] associated with the Ahu-O-Laka turtles. Fatty acid profiles of turtles from both locations differed substantially from those of their benthic diets, suggesting considerable modification of dietary fatty acids and de novo biosynthesis.

  7. Stochasticity in natural forage production affects use of urban areas by black bears: implications to management of human-bear conflicts.

    PubMed

    Baruch-Mordo, Sharon; Wilson, Kenneth R; Lewis, David L; Broderick, John; Mao, Julie S; Breck, Stewart W

    2014-01-01

    The rapid expansion of global urban development is increasing opportunities for wildlife to forage and become dependent on anthropogenic resources. Wildlife using urban areas are often perceived dichotomously as urban or not, with some individuals removed in the belief that dependency on anthropogenic resources is irreversible and can lead to increased human-wildlife conflict. For American black bears (Ursus americanus), little is known about the degree of bear urbanization and its ecological mechanisms to guide the management of human-bear conflicts. Using 6 years of GPS location and activity data from bears in Aspen, Colorado, USA, we evaluated the degree of bear urbanization and the factors that best explained its variations. We estimated space use, activity patterns, survival, and reproduction and modeled their relationship with ecological covariates related to bear characteristics and natural food availability. Space use and activity patterns were dependent on natural food availability (good or poor food years), where bears used higher human density areas and became more nocturnal in poor food years. Patterns were reversible, i.e., individuals using urban areas in poor food years used wildland areas in subsequent good food years. While reproductive output was similar across years, survival was lower in poor food years when bears used urban areas to a greater extent. Our findings suggest that bear use of urban areas is reversible and fluctuates with the availability of natural food resources, and that removal of urban individuals in times of food failures has the potential to negatively affect bear populations. Given that under current predictions urbanization is expected to increase by 11% across American black bear range, and that natural food failure years are expected to increase in frequency with global climate change, alternative methods of reducing urban human-bear conflict are required if the goal is to prevent urban areas from becoming population sinks.

  8. Stochasticity in Natural Forage Production Affects Use of Urban Areas by Black Bears: Implications to Management of Human-Bear Conflicts

    PubMed Central

    Baruch-Mordo, Sharon; Wilson, Kenneth R.; Lewis, David L.; Broderick, John; Mao, Julie S.; Breck, Stewart W.

    2014-01-01

    The rapid expansion of global urban development is increasing opportunities for wildlife to forage and become dependent on anthropogenic resources. Wildlife using urban areas are often perceived dichotomously as urban or not, with some individuals removed in the belief that dependency on anthropogenic resources is irreversible and can lead to increased human-wildlife conflict. For American black bears (Ursus americanus), little is known about the degree of bear urbanization and its ecological mechanisms to guide the management of human-bear conflicts. Using 6 years of GPS location and activity data from bears in Aspen, Colorado, USA, we evaluated the degree of bear urbanization and the factors that best explained its variations. We estimated space use, activity patterns, survival, and reproduction and modeled their relationship with ecological covariates related to bear characteristics and natural food availability. Space use and activity patterns were dependent on natural food availability (good or poor food years), where bears used higher human density areas and became more nocturnal in poor food years. Patterns were reversible, i.e., individuals using urban areas in poor food years used wildland areas in subsequent good food years. While reproductive output was similar across years, survival was lower in poor food years when bears used urban areas to a greater extent. Our findings suggest that bear use of urban areas is reversible and fluctuates with the availability of natural food resources, and that removal of urban individuals in times of food failures has the potential to negatively affect bear populations. Given that under current predictions urbanization is expected to increase by 11% across American black bear range, and that natural food failure years are expected to increase in frequency with global climate change, alternative methods of reducing urban human-bear conflict are required if the goal is to prevent urban areas from becoming population sinks

  9. Modelling Pasture-based Automatic Milking System Herds: System Fitness of Grazeable Home-grown Forages, Land Areas and Walking Distances

    PubMed Central

    Islam, M. R.; Garcia, S. C.; Clark, C. E. F.; Kerrisk, K. L.

    2015-01-01

    To maintain a predominantly pasture-based system, the large herd milked by automatic milking rotary would be required to walk significant distances. Walking distances of greater than 1-km are associated with an increased incidence of undesirably long milking intervals and reduced milk yield. Complementary forages can be incorporated into pasture-based systems to lift total home grown feed in a given area, thus potentially ‘concentrating’ feed closer to the dairy. The aim of this modelling study was to investigate the total land area required and associated walking distance for large automatic milking system (AMS) herds when incorporating complementary forage rotations (CFR) into the system. Thirty-six scenarios consisting of 3 AMS herds (400, 600, 800 cows), 2 levels of pasture utilisation (current AMS utilisation of 15.0 t dry matter [DM]/ha, termed as moderate; optimum pasture utilisation of 19.7 t DM/ha, termed as high) and 6 rates of replacement of each of these pastures by grazeable CFR (0%, 10%, 20%, 30%, 40%, 50%) were investigated. Results showed that AMS cows were required to walk greater than 1-km when the farm area was greater than 86 ha. Insufficient pasture could be produced within a 1 km distance (i.e. 86 ha land) with home-grown feed (HGF) providing 43%, 29%, and 22% of the metabolisable energy (ME) required by 400, 600, and 800 cows, respectively from pastures. Introduction of pasture (moderate): CFR in AMS at a ratio of 80:20 can feed a 400 cow AMS herd, and can supply 42% and 31% of the ME requirements for 600 and 800 cows, respectively with pasture (moderate): CFR at 50:50 levels. In contrast to moderate pasture, 400 cows can be managed on high pasture utilisation (provided 57% of the total ME requirements). However, similar to the scenarios conducted with moderate pasture, there was insufficient feed produced within 1-km distance of the dairy for 600 or 800 cows. An 800 cow herd required 140 and 130 ha on moderate and high pasture-based AMS

  10. Modelling Pasture-based Automatic Milking System Herds: System Fitness of Grazeable Home-grown Forages, Land Areas and Walking Distances.

    PubMed

    Islam, M R; Garcia, S C; Clark, C E F; Kerrisk, K L

    2015-06-01

    To maintain a predominantly pasture-based system, the large herd milked by automatic milking rotary would be required to walk significant distances. Walking distances of greater than 1-km are associated with an increased incidence of undesirably long milking intervals and reduced milk yield. Complementary forages can be incorporated into pasture-based systems to lift total home grown feed in a given area, thus potentially 'concentrating' feed closer to the dairy. The aim of this modelling study was to investigate the total land area required and associated walking distance for large automatic milking system (AMS) herds when incorporating complementary forage rotations (CFR) into the system. Thirty-six scenarios consisting of 3 AMS herds (400, 600, 800 cows), 2 levels of pasture utilisation (current AMS utilisation of 15.0 t dry matter [DM]/ha, termed as moderate; optimum pasture utilisation of 19.7 t DM/ha, termed as high) and 6 rates of replacement of each of these pastures by grazeable CFR (0%, 10%, 20%, 30%, 40%, 50%) were investigated. Results showed that AMS cows were required to walk greater than 1-km when the farm area was greater than 86 ha. Insufficient pasture could be produced within a 1 km distance (i.e. 86 ha land) with home-grown feed (HGF) providing 43%, 29%, and 22% of the metabolisable energy (ME) required by 400, 600, and 800 cows, respectively from pastures. Introduction of pasture (moderate): CFR in AMS at a ratio of 80:20 can feed a 400 cow AMS herd, and can supply 42% and 31% of the ME requirements for 600 and 800 cows, respectively with pasture (moderate): CFR at 50:50 levels. In contrast to moderate pasture, 400 cows can be managed on high pasture utilisation (provided 57% of the total ME requirements). However, similar to the scenarios conducted with moderate pasture, there was insufficient feed produced within 1-km distance of the dairy for 600 or 800 cows. An 800 cow herd required 140 and 130 ha on moderate and high pasture-based AMS

  11. Enrichment and shifts in macrobenthic assemblages in an offshore wind farm area in the Belgian part of the North Sea.

    PubMed

    Coates, Delphine A; Deschutter, Yana; Vincx, Magda; Vanaverbeke, Jan

    2014-04-01

    The growing development of offshore wind energy installations across the North Sea is producing new hard anthropogenic structures in the natural soft sediments, causing changes to the surrounding macrobenthos. The extent of modification in permeable sediments around a gravity based wind turbine in the Belgian part of the North Sea was investigated in the period 2011-2012, along four gradients (south-west, north-east, south-east, north-west). Sediment grain size significantly reduced from 427 μm at 200 m to 312 ± 3 μm at 15 m from the foundation along the south-west and north-west gradients. The organic matter content increased from 0.4 ± 0.01% at 100 m to 2.5 ± 0.9% at 15 m from the foundation. The observed changes in environmental characteristics triggered an increase in the macrobenthic density from 1390 ± 129 ind m⁻² at 200 m to 18 583 ± 6713 ind m⁻² at 15 m together with an enhanced diversity from 10 ± 2 at 200 m to 30 ± 5 species per sample at 15 m. Shifts in species dominance were also detected with a greater dominance of the ecosystem-engineer Lanice conchilega (16-25%) close to the foundation. This study suggests a viable prediction of the effects offshore wind farms could create to the naturally occurring macrobenthos on a large-scale.

  12. New insights into the evolution of central Tyrrhenian margin of Italy (northern Latium off-shore area): evidences and constraints from seismic data interpretation

    NASA Astrophysics Data System (ADS)

    Buttinelli, M.; Vico, G.; Scrocca, D.; Petracchini, L.; de Rita, D.

    2009-04-01

    A revision of the available seismic reflection survey in the off-shore part of the northern Latium (central Italy) has been accomplished to better understand the deep structural setting of this area. Previous works performed in the last twenty years have compared the on-shore outcrops of cretaceous flyschoid and Plio-Pleistocene marine sedimentary units with shallow off-shore seismic reflection data (1/1,5 msec twt maximum), while the deep structural setting of calcareous basement of Tuscan units have been poorly analysed. The stratigraphy of the area is well constrained by a deep well, which goes through the entire sedimentary succession. Other geological constraints are provided by a discrete amount of deep wells in the on-shore part of the study area and by a voluminous bibliography, in which many authors tried to correlate this units to the tectonic units described in the central and northern part of the Apennines. The stratigraphy could be divided in four main groups of units; from top to bottom: Plio-Pleistocene marine deposits, Cretaceous Liguride deep-water units, Jurassic Tuscan pelagic deposits, and a Triassic evaporitic formation. Even volcanic intrusive bodies (Tolfa-Ceriti-Manziana dome complexes) are present in the on-shore part. The emplacement of this bodies generally caused a further overprint on the different deformation phases that affected this area. Seismic reflection data analysis show that this area was affected by at least three deformational phases. After the deposition of the Tuscan and Liguride sedimentary units, the area underwent: i) an initial compressional phase associated to the Alps-Northern Apennine chain build up, with formation of compressional features as regional thrusts, back-thrusts and fold structures. These structures are clearly visible in the deep Tuscan and Liguride units setting; ii) a successive extensional deformation phase related to the spreading of the Tyrrhenian Sea, starting in the late Miocene times. This caused

  13. Converting Predation Cues into Conservation Tools: The Effect of Light on Mouse Foraging Behaviour

    PubMed Central

    Farnworth, Bridgette; Innes, John; Waas, Joseph R.

    2016-01-01

    Prey face a conflict between acquiring energy and avoiding predators and use both direct and indirect cues to assess predation risk. Illumination, an indirect cue, influences nocturnal rodent foraging behaviour. New Zealand holds no native rodent species but has introduced mice (Mus musculus) that severely impair native biodiversity. We used Giving-Up Densities (GUDs) and observations of foraging frequency and duration to assess if artificial light induces risk avoidance behaviour in mice and could limit their activity. We found both captive (wild strain) mice in outdoor pens and wild mice within a pest fenced sanctuary (Maungatautari, New Zealand) displayed avoidance behaviour in response to illumination. In captivity, total foraging effort was similar across lit and unlit pens but mice displayed a strong preference for removing seeds from dark control areas (mean: 15.33 SD: +/-11.64 per 3.5 hours) over illuminated areas (2.00 +/-3.44). Wild mice also removed fewer seeds from illuminated areas (0.42 +/-1.00 per 12 hours) compared to controls (6.67 +/-9.20). Captive mice spent less than 1.0% of available time at illuminated areas, versus 11.3% at controls; visited the lit areas less than control areas (12.00 +/- 9.77 versus 29.00 +/-21.58 visits respectively); and spent less time per visit at illuminated versus control areas (8.17 +/-7.83 versus 44.83 +/-87.52 seconds per visit respectively). Illumination could provide protection at ecologically sensitive sites, damaged exclusion fences awaiting repair, fence terminus zones of peninsula sanctuaries and shipping docks that service offshore islands. We promote the hypothesis that the tendency of mice to avoid illumination could be a useful conservation tool, and advance knowledge of risk assessment and foraging under perceived danger. PMID:26760039

  14. Smarter offshoring.

    PubMed

    Farrell, Diana

    2006-06-01

    During the past 15 years, companies have flocked to a handful of cities in India and Eastern Europe for offshore service functions. As a result, the most popular sites are now overheating: Demand for young professionals is outstripping supply, wages and turnover are soaring, and overburdened infrastructure systems are struggling to serve the explosive growth. The happy news is that the tight labor markets in the well-known hot spots are the exceptions, not the rule. Many attractive alternatives are emerging around the world. According to a McKinsey Global Institute study, more than 90% of the vast and rapidly growing pool of university-educated people suitable for work in multinationals are located outside the current hot spot cities. For instance, Morocco is now home to offshore centers for French and Spanish companies requiring fluent speakers of their home languages. Neighboring Tunisia has used its modern infrastructure, business-friendly regulations, and stable, low-cost workforce to attract companies such as Siemens and Wanadoo. Vietnam offers university graduates who have strong mathematics skills; speak French, English, German, or Russian; and do not demand high wages. The problems facing the hot spots, coupled with the emergence of many more countries able and willing to provide offshore services, mean that picking a site has become more complicated. In choosing a location, companies will have to focus less on low wages and much more on other ways that candidate cities can fulfill their business needs. They will have to be much more rigorous in articulating precisely what they require from an offshore location. That means evaluating their unique needs on a range of dimensions and understanding how alternative locations can meet those needs for the foreseeable future.

  15. Habitat-specific foraging strategies in Australasian gannets

    PubMed Central

    Wells, Melanie R.; Arnould, John P. Y.

    2016-01-01

    ABSTRACT Knowledge of top predator foraging adaptability is imperative for predicting their biological response to environmental variability. While seabirds have developed highly specialised techniques to locate prey, little is known about intraspecific variation in foraging strategies with many studies deriving information from uniform oceanic environments. Australasian gannets (Morus serrator) typically forage in continental shelf regions on small schooling prey. The present study used GPS and video data loggers to compare habitat-specific foraging strategies at two sites of contrasting oceanographic regimes (deep water near the continental shelf edge, n=23; shallow inshore embayment, n=26), in south-eastern Australia. Individuals from the continental shelf site exhibited pelagic foraging behaviours typical of gannet species, using local enhancement to locate and feed on small schooling fish; in contrast only 50% of the individuals from the inshore site foraged offshore, displaying the typical pelagic foraging strategy. The remainder adopted a strategy of searching sand banks in shallow inshore waters in the absence of conspecifics and other predators for large, single prey items. Furthermore, of the individuals foraging inshore, 93% were male, indicating that the inshore strategy may be sex-specific. Large inter-colony differences in Australasian gannets suggest strong plasticity in foraging behaviours, essential for adapting to environmental change. PMID:27305927

  16. Habitat-specific foraging strategies in Australasian gannets.

    PubMed

    Wells, Melanie R; Angel, Lauren P; Arnould, John P Y

    2016-07-15

    Knowledge of top predator foraging adaptability is imperative for predicting their biological response to environmental variability. While seabirds have developed highly specialised techniques to locate prey, little is known about intraspecific variation in foraging strategies with many studies deriving information from uniform oceanic environments. Australasian gannets (Morus serrator) typically forage in continental shelf regions on small schooling prey. The present study used GPS and video data loggers to compare habitat-specific foraging strategies at two sites of contrasting oceanographic regimes (deep water near the continental shelf edge, n=23; shallow inshore embayment, n=26), in south-eastern Australia. Individuals from the continental shelf site exhibited pelagic foraging behaviours typical of gannet species, using local enhancement to locate and feed on small schooling fish; in contrast only 50% of the individuals from the inshore site foraged offshore, displaying the typical pelagic foraging strategy. The remainder adopted a strategy of searching sand banks in shallow inshore waters in the absence of conspecifics and other predators for large, single prey items. Furthermore, of the individuals foraging inshore, 93% were male, indicating that the inshore strategy may be sex-specific. Large inter-colony differences in Australasian gannets suggest strong plasticity in foraging behaviours, essential for adapting to environmental change.

  17. Onshore and offshore wind resource evaluation in the northeastern area of the Iberian Peninsula: quality assurance of the surface wind observations

    NASA Astrophysics Data System (ADS)

    Hidalgo, A.; González-Rouco, J. F.; Jiménez, P. A.; Navarro, J.; García-Bustamante, E.; Lucio-Eceiza, E. E.; Montávez, J. P.; García, A. Y.; Prieto, L.

    2012-04-01

    Offshore wind energy is becoming increasingly important as a reliable source of electricity generation. The areas located in the vicinity of the Cantabrian and Mediterranean coasts are areas of interest in this regard. This study targets an assessment of the wind resource focused on the two coastal regions and the strip of land between them, thereby including most of the northeastern part of the Iberian Peninsula (IP) and containing the Ebro basin. The analysis of the wind resource in inland areas is crucial as the wind channeling through the existing mountains has a direct impact on the sea circulations near the coast. The thermal circulations generated by the topography near the coast also influence the offshore wind resource. This work summarizes the results of the first steps of a Quality Assurance (QA) procedure applied to the surface wind database available over the area of interest. The dataset consists of 752 stations compiled from different sources: 14 buoys distributed over the IP coast provided by Puertos del Estado (1990-2010); and 738 land sites over the area of interest provided by 8 different Spanish institutions (1933-2010) and the National Center of Atmospheric Research (NCAR; 1978-2010). It is worth noting that the variety of institutional observational protocols lead to different temporal resolutions and peculiarities that somewhat complicate the QA. The QA applied to the dataset is structured in three steps that involve the detection and suppression of: 1) manipulation errors (i.e. repetitions); 2) unrealistic values and ranges in wind module and direction; 3) abnormally low (e.g. long constant periods) and high variations (e.g. extreme values and inhomogeneities) to ensure the temporal consistency of the time series. A quality controlled observational network of wind variables with such spatial density and temporal length is not frequent and specifically for the IP is not documented in the literature. The final observed dataset will allow for a

  18. Integrated forage crop refinery system

    SciTech Connect

    Barrier, J.W.; Broder, J.D.; Madewell, C.E.; Mays, D.A.

    1985-04-01

    The proposed program involves the development of an integrated agricultural-chemical refining system for converting forage crops to useful foods, feeds, fuels, and chemicals. TVA has facilities and resources available to support extensive research and development activities. Modification can easily be made in the existing experimental facility being used to develop acid hydrolysis of corn stover, to include production of products other than fuel ethanol from forages. These products include protein, lignin-derived products, chemicals, single-cell protein, methane, aquaculture feed, and distillers solids. Refining forage crops in this manner has potential to increase the value of that crop and produce an economical integrated system. The results of the program will also be directly applicable to other areas and regions of the US. 11 refs., 7 figs., 9 tabs.

  19. Middle Eocene Nummulites and their offshore re-deposition: A case study from the Middle Eocene of the Venetian area, northeastern Italy

    NASA Astrophysics Data System (ADS)

    Bassi, Davide; Nebelsick, James H.; Puga-Bernabéu, Ángel; Luciani, Valeria

    2013-11-01

    The Middle Eocene Calcari nummulitici formation from northeastern Italy, Venetian area, represents a shallow-marine carbonate ramp developed on the northern Tethyan margin. In the Monti Berici area, its main components are larger foraminifera and coralline red algal communities that constitute thick carbonate sedimentary successions. Middle ramp and proximal outer ramp environments are recognized using component relationships, biofacies and sedimentary features. The middle-ramp is characterized by larger flattened-lenticular Nummulites on palaeohighs between which rhodoliths formed. Larger Nummulites palaeohighs containing Nummulites millecaput, Nummulites crassus, Nummulites discorbinus and Nummulites cf. gizehensis developed more basin-wards. The following relatively quiet environments of basin-wards of the palaeohighs represent areas of maximum carbonate production. The transition between the distal middle- and the proximal outer-ramp settings is marked in the study area by a large erosional surface which is interpreted to have been formed as a result of an erosive channel body filled in by deposits re-sedimented from shallower depths. These off-shore re-sedimented channelized deposits, ascribed to the Shallow Benthic Zone SBZ 15, lying on hemipelagic marls (planktonic foraminiferal zone E9 (P11)) allow for a biostratigraphic correlation to the Late Lutetian. The studied deposits, represented by packstone to rudstones, were displaced whilst still unlithified. The Lutetian-Bartonian regression along with the local tectonic activity promoted the production of a high amount of biogenic shallow-water carbonates mainly produced in the Mossano middle-ramp settings. These prograded towards the basinal areas with high-sedimentation rate of carbonate deposits characterized by the larger Nummulites rudstones. Such high amounts of sediment led to sediment instability which potentially could be mobilized either by return currents due to occasional major storms or by

  20. California Least Tern Foraging Ecology in Southern California: A Review of Foraging Behavior Relative to Proposed Dredging Locations

    DTIC Science & Technology

    2016-05-01

    ER D C/ EL C R- 16 -3 Dredging Operations and Environmental Research Program California Least Tern Foraging Ecology in Southern...client/default. Dredging Operations and Environmental Research Program ERDC/EL CR-16-3 May 2016 California Least Tern Foraging Ecology in...reviewed for an overview of CLT foraging ecology , and so that CLT tendencies to forage in habitats near CCW could be inferred for areas where no

  1. Plasticity in foraging strategies of inshore birds: how Little Penguins maintain body reserves while feeding offspring.

    PubMed

    Saraux, Claire; Robinson-Laverick, Sarah M; Le Maho, Yvon; Ropert-Coudert, Yan; Chiaradia, André

    2011-10-01

    Breeding animals face important time and energy constraints when caring for themselves and their offspring. For long-lived species, life-history theory predicts that parents should favor survival over current reproductive attempts, thus investing more into their own maintenance than the provisioning of their young. In seabirds, provisioning strategies may additionally be influenced by the distance between breeding sites and foraging areas, and offshore and inshore species should thus exhibit different strategies. Here, we examine the provisioning strategies of an inshore seabird using a long-term data set on more than 200 Little Penguins, Eudyptula minor. They alternated between two consecutive long and several short foraging trips all along chick rearing, a strategy almost never observed for inshore animals. Short trips allowed for regular provisioning of the chicks (high feeding frequency and larger meals), whereas long trips were performed when parent body mass was low and enabled them to rebuild their reserves, suggesting that adult body condition may be a key factor in initiating long trips. Inshore seabirds do use dual strategies of alternating short and long trips, but from our data, on a simpler and less flexible way than for offshore birds.

  2. 33 CFR 334.845 - Wisconsin Air National Guard, Volk Field military exercise area located in Lake Michigan offshore...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... vessels entering the danger zone are advised to proceed across the area by the most direct route and... size shall lie-to or anchor in the danger zone, other than a vessel operated by or for the USCG, or...

  3. Is there an endogenous tidal foraging rhythm in marine iguanas?

    PubMed

    Wikelski, M; Hau, M

    1995-12-01

    As strictly herbivorous reptiles, Galápagos marine iguanas graze on algae in the intertidal areas during low tide. Daily foraging rhythms were observed on two islands during 3 years to determine the proximate factors underlying behavioral synchrony with the tides. Marine iguanas walked to their intertidal foraging grounds from far-off resting areas in anticipation of the time of low tide. Foraging activity was restricted to daytime, resulting in a complex bitidal rhythm including conspicuous switches from afternoon foraging to foraging during the subsequent morning when low tide occurred after dusk. The animals anticipated the daily low tide by a maximum of 4 h. The degree of anticipation depended on environmental parameters such as wave action and food supply. "Early foragers" survived in greater numbers than did animals arriving later at foraging sites, a result indicating selection pressure on the timing of anticipation. The timing of foraging trips was better predicted by the daily changes in tabulated low tide than it was by the daily changes in actual exposure of the intertidal foraging flats, suggesting an endogenous nature of the foraging rhythms. Endogenous rhythmicity would also explain why iguanas that had spontaneously fasted for several days nevertheless went foraging at the "right" time of day. A potential lunar component of the foraging rhythmicity of marine iguanas showed up in their assemblage on intertidal rocks during neap tide nights. This may indicate that iguanas possessed information on the semi-monthly rhythms in tide heights. Enclosure experiments showed that bitidal foraging rhythms of iguanas may free run in the absence of direct cues from the intertidal areas and operate independent of the light:dark cycle and social stimuli. Therefore, the existence of a circatidal oscillator in marine iguanas is proposed. The bitidal foraging pattern may result from an interaction of a circadian system with a circatidal system. Food intake or related

  4. Offshore Space Center (offshore launch site)

    NASA Technical Reports Server (NTRS)

    Harvey, D. G.

    1980-01-01

    Any activity requiring the development of the HLLV can benefit by operations from an offshore space center (OSC) since operating near the equator provides a twenty percent increase in payload in an ecliptic plan orbit. Some OSC concepts considered include a moored floating (semisubmersible) design, a stationary design supported by fixed piles, and a combination of these two. The facility supports: a 15,000 foot long, 300 foot wide runway, designed to accommodate a two staged winged launch vehicle, with a one million pound payload capacity to low earth orbit; an industrial area for HLLV maintenance; an airport terminal, control and operation center, and observation tower; liquid hydrogen and liquid oxygen production and storage, and fuel storage platforms; a power generation station, docks with an unloading area; two separate launch sites; and living accommodations for 10,000 people. Potential sites include the Paramount Seamount in the Pacific Ocean off the north coast of South America. Cost estimates are considered.

  5. Geology of the Cape Mendocino, Eureka, Garberville, and Southwestern Part of the Hayfork 30 x 60 Minute Quadrangles and Adjacent Offshore Area, Northern California

    USGS Publications Warehouse

    McLaughlin, Robert J.; Ellen, S.D.; Blake, M.C.; Jayko, Angela S.; Irwin, W.P.; Aalto, K.R.; Carver, G.A.; Clarke, S.H.; Barnes, J.B.; Cecil, J.D.; Cyr, K.A.

    2000-01-01

    Introduction These geologic maps and accompanying structure sections depict the geology and structure of much of northwestern California and the adjacent continental margin. The map area includes the Mendocino triple junction, which is the juncture of the North American continental plate with two plates of the Pacific ocean basin. The map area also encompasses major geographic and geologic provinces of northwestern California. The maps incorporate much previously unpublished geologic mapping done between 1980 and 1995, as well as published mapping done between about 1950 and 1978. To construct structure sections to mid-crustal depths, we integrate the surface geology with interpretations of crustal structure based on seismicity, gravity and aeromagnetic data, offshore structure, and seismic reflection and refraction data. In addition to describing major geologic and structural features of northwestern California, the geologic maps have the potential to address a number of societally relevant issues, including hazards from earthquakes, landslides, and floods and problems related to timber harvest, wildlife habitat, and changing land use. All of these topics will continue to be of interest in the region, as changing land uses and population density interact with natural conditions. In these interactions, it is critical that the policies and practices affecting man and the environment integrate an adequate understanding of the geology. This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (ceghmf.ps, ceghmf.pdf, ceghmf.txt), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The

  6. Methane flux estimation of a large seep area offshore Svalbard based on visual observations and inverse hydroacoustic modeling

    NASA Astrophysics Data System (ADS)

    Veloso, Mario; Mienert, Jurgen; De Batist, Marc; Greinert, Jens

    2014-05-01

    A seep site area at west of Prins Karl Forland (Svalbard) has been monitored since 2009 in order to evaluate its changes in space and time. Hydroacoustic data captured over four years have been used to understand the dynamic of the gas release and quantify the flow rate of gas coming from the seabed. Echograms indicate that gas release occurs between 200 and 400 mbsl and show that some of the acoustic flares reach the surface. Hydroacoustic data was captured with the EK60 echosounder system which uses a split-beam technique to determine the backscattering position inside the beam. The data obtained gives accurate information of the spatial distribution of the backscattering produced by bubble release. Gas release spot positions have been obtained using a geometrical average of spatial distribution of the backscattering, produced by the bubble cloud above the seafloor. An inverse hydroacoustic method developed by Muyakshin et al (Muyakshin et al. 2010) has been used to quantify the flow rate of the gas release. The method uses as input the backscattering volume strength (SV ) of the bubble release above the seafloor, bubble size distribution (BSD) obtained from underwater video footage and bubble rising speed (BRS) values determined by models developed by different researchers (e.g., Leifer and Patro, 2002, Woolf 1993, Mendelson 1967). Gridding and interpolation of the acoustic information obtained from Sv values has been carried out, adapting the method in order to be used over a large area. Flow rate calculations of a selected area (~220 mbsl) have been carried out (using different BRS models and merged data from different years) giving values between 220 and 347 T/yr of methane assuming continuous discharge and a bubble containing 100% of CH4. Temporal variability of methane fluxes was evaluated using the 'common' insonified areas with acoustic information of gas release over the seafloor. Comparison of calculated fluxes from common areas have shown that methane

  7. Reduced inorganic sulfur in surface sediment and its impact on benthic environments in offshore areas of NE China.

    PubMed

    Sheng, Yanqing; Sun, Qiyao; Bottrell, Simon H; Mortimer, Robert J G

    2015-09-01

    Geochemical cycling and biological toxicity of sulfur in marine sediments is closely related to the activity of organisms. This study investigated the distribution and potential impact on benthic environments of acid volatile sulfur (AVS), chromium(II)-reducible sulfur (CRS), elemental sulfur (ES), total S, C, N and Fe in superficial sediments across the Bohai Sea, Yellow Sea and East China Sea. The composition of reduced inorganic sulfur in the three study areas was dominated by CRS (averaging 72% of total reduced inorganic sulfur). The low AVS content (average of 1.12 μmol g(-1)) of the sediments and the low values of AVS/CRS (average 0.34 μmol g(-1)), degree of pyritization and degree of sulphidization indicate that there is sufficient available iron in the sediment to restrict the threat of sulphide toxicity to benthic organisms in most of the study areas. However, high organic matter loads in parts of the study areas have resulted in enhanced accumulation of AVS, resulting in a higher toxicity risk.

  8. PAH assessment in the main Brazilian offshore oil and gas production area using semi-permeable membrane devices (SPMD) and transplanted bivalves

    NASA Astrophysics Data System (ADS)

    André Lourenço, Rafael; Francisco de Oliveira, Fábio; Haddad Nudi, Adriana; Rebello Wagener, Ângela de Luca; Guadalupe Meniconi, Maria de Fátima; Francioni, Eleine

    2015-06-01

    The Campos Basin is Brazil's main oil and gas production area. In 2013, more than 50 million cubic meters of produced water (PW) was discharged into these offshore waters. Despite the large volumes of PW that are discharged in the Campos Basin each day, the ecological concern of the chemicals in the PW are not completely understood. Polycyclic aromatic hydrocarbons (PAH) are the most important contributors to the ecological hazards that are posed by discharged PW. This study aimed to evaluate the potential bioaccumulation of PAH using transplanted bivalves (Nodipecten nodosus) and semi-permeable membrane devices (SPMD). The study was conducted in two platforms that discharge PW (P19 and P40). Another platform that does not discharge PW (P25) was investigated for comparison with the obtained results. Time-integrated hydrocarbon concentrations using SPMD and transplanted bivalves were estimated from the seawater near the three platforms. The bioaccumulation of the PAH in the transplanted bivalves at platforms P19 and P40 were up to fivefold greater than the bioaccumulation of the PAH at platform P25. The lowest PAH concentrations were estimated for platform P25 (4.3-6.2 ng L-1), and the highest PAH concentrations were estimated for platform P19 (9.2-37.3 ng L-1). Both techniques were effective for determining the bioavailability of the PAH and for providing time-integrated hydrocarbon concentrations regarding oil and gas production activities.

  9. Marine foraging ecology influences mercury bioaccumulation in deep-diving northern elephant seals

    USGS Publications Warehouse

    Peterson, Sarah H.; Ackerman, Joshua T.; Costa, Daniel P.

    2015-01-01

    Mercury contamination of oceans is prevalent worldwide and methylmercury concentrations in the mesopelagic zone (200–1000 m) are increasing more rapidly than in surface waters. Yet mercury bioaccumulation in mesopelagic predators has been understudied. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometres to forage within coastal and open-ocean regions of the northeast Pacific Ocean. We coupled satellite telemetry, diving behaviour and stable isotopes (carbon and nitrogen) from 77 adult females, and showed that variability among individuals in foraging location, diving depth and δ13C values were correlated with mercury concentrations in blood and muscle. We identified three clusters of foraging strategies, and these resulted in substantially different mercury concentrations: (i) deeper-diving and offshore-foraging seals had the greatest mercury concentrations, (ii) shallower-diving and offshore-foraging seals had intermediate levels, and (iii) coastal and more northerly foraging seals had the lowest mercury concentrations. Additionally, mercury concentrations were lower at the end of the seven-month-long foraging trip (n = 31) than after the two-month- long post-breeding trip (n = 46). Our results indicate that foraging behaviour influences mercury exposure and mesopelagic predators foraging in the northeast Pacific Ocean may be at high risk for mercury bioaccumulation.

  10. Marine foraging ecology influences mercury bioaccumulation in deep-diving northern elephant seals

    PubMed Central

    Peterson, Sarah H.; Ackerman, Joshua T.; Costa, Daniel P.

    2015-01-01

    Mercury contamination of oceans is prevalent worldwide and methylmercury concentrations in the mesopelagic zone (200–1000 m) are increasing more rapidly than in surface waters. Yet mercury bioaccumulation in mesopelagic predators has been understudied. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometres to forage within coastal and open-ocean regions of the northeast Pacific Ocean. We coupled satellite telemetry, diving behaviour and stable isotopes (carbon and nitrogen) from 77 adult females, and showed that variability among individuals in foraging location, diving depth and δ13C values were correlated with mercury concentrations in blood and muscle. We identified three clusters of foraging strategies, and these resulted in substantially different mercury concentrations: (i) deeper-diving and offshore-foraging seals had the greatest mercury concentrations, (ii) shallower-diving and offshore-foraging seals had intermediate levels, and (iii) coastal and more northerly foraging seals had the lowest mercury concentrations. Additionally, mercury concentrations were lower at the end of the seven-month-long foraging trip (n = 31) than after the two-month- long post-breeding trip (n = 46). Our results indicate that foraging behaviour influences mercury exposure and mesopelagic predators foraging in the northeast Pacific Ocean may be at high risk for mercury bioaccumulation. PMID:26085591

  11. Marine foraging ecology influences mercury bioaccumulation in deep-diving northern elephant seals.

    PubMed

    Peterson, Sarah H; Ackerman, Joshua T; Costa, Daniel P

    2015-07-07

    Mercury contamination of oceans is prevalent worldwide and methylmercury concentrations in the mesopelagic zone (200-1000 m) are increasing more rapidly than in surface waters. Yet mercury bioaccumulation in mesopelagic predators has been understudied. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometres to forage within coastal and open-ocean regions of the northeast Pacific Ocean. We coupled satellite telemetry, diving behaviour and stable isotopes (carbon and nitrogen) from 77 adult females, and showed that variability among individuals in foraging location, diving depth and δ(13)C values were correlated with mercury concentrations in blood and muscle. We identified three clusters of foraging strategies, and these resulted in substantially different mercury concentrations: (i) deeper-diving and offshore-foraging seals had the greatest mercury concentrations, (ii) shallower-diving and offshore-foraging seals had intermediate levels, and (iii) coastal and more northerly foraging seals had the lowest mercury concentrations. Additionally, mercury concentrations were lower at the end of the seven-month-long foraging trip (n = 31) than after the two-month- long post-breeding trip (n = 46). Our results indicate that foraging behaviour influences mercury exposure and mesopelagic predators foraging in the northeast Pacific Ocean may be at high risk for mercury bioaccumulation.

  12. Integration of Seismic Sequence Analysis and High Resolution Sequence Stratigraphy for Delineating the Sedimentation Characteristics and Modeling of Baltim Area, Off-Shore Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Nasr El-Deen Badawy, A. M. E. S.; Abu El-Ata, A. S. A.; El-Gendy, N. H.

    2014-12-01

    The current study is aiming to discuss the Messinian Prospectivity of the concerned area, which is located in the offshore Nile Delta, about 25 Km from the Mediterranean Sea shoreline. An integrated exploration approach applied, using a variety of the 2D/3D seismic data, subsurface borehole geologic and log data of the selected wells distributed in the study area, as well as the geophysical and biostratigraphic data. The well data comprise well markers, and electric logs, where the geological data represented by litho-stratigraphic information, as well as ditch samples analysis of the studied interval. The geophysical data include check shots, VSP, velocity cubes and 3D seismic lines. Biostratigraphic data include biozones, benthonic to planktonic ratios, nannofossils and foraminiferal data. Seismic interpretation and seismic stratigraphic analysis, in the form of seismic sequence analysis, seismic facies analysis, seismic unit analysis and geologic confirmation have been done by the aid of Petrel and Kingdom computer softwares. The seismic lines were interpreted for defining the different parasequences and picking the various smaller sequences for mapping, after picking each sequence from the seismic correlation, it is facilitated the mapping of every sequence laterally. In addition, the interpretation of structures and isopach of every sequence has been carried out, and the seismic attributes for every sequence were possible, to extract the sands present in each sequence, and to study the extensions of these sands that act as a reservoir. The integration of all results was taken as a base to produce the various models for the study area. The first one was the depositional environmental model, which showed that, the area varies from intertidal-littoral southward at Nidoco wells to inner-middle neritic at Baltim East wells then to outer neritic, and changes to bathyal and then to abyssal at the extreme north. The geologic model for the area was constructed

  13. Aircraft measurements of SO2, NOx, CO, and O3 over the coastal and offshore area of Yellow Sea of China.

    PubMed

    Yang, Xiaoyang; Wang, Xinhua; Yang, Wen; Xu, Jun; Ren, Lihong; He, Youjiang; Liu, Bing; Bai, Zhipeng; Meng, Fan; Hu, Min

    2016-09-01

    In order to investigate long-range transport of the air pollution in the East Asia, air pollutants, including SO2, NOx, CO, and O3, were observed by aircraft measurement over the coastal and offshore area of Yellow Sea of China in April 2011. NOx and SO2 seemed to become moderate in recent years, and the concentrations during the whole observations ranged from 0.49 to 9.57 ppb and from 0.10 to 16.02 ppb, respectively. The high concentrations of CO were measured with an average value of 0.98 ppm. The measured O3 average concentration was 76.25 ppb, which showed a higher level comparing with the results from some previous studies. Most of the results for the concentration values generally followed the typical characteristic of vertical and spatial distribution, which were "low altitude > high altitude" and "land/coastal > sea," respectively. Transport of polluted air mass from the continent to the aircraft measurement area was confirmed in some days during the observation by the meteorological analysis, while the measurement results supposed to represent the background level of the pollutants in rest days. Additionally, some small-scale air pollution plumes were observed. Significant positive correlations between NOx and SO2 indicated that these two species originated from the same region. On the other hand, good positive correlations between NOx and O3 found during 2-day flight suggested that the O3 formation was probably under "NOx-limited" regime in these days.

  14. Retrieval of Secchi disk depth in offshore marine areas based on simulated HICO from in-situ hyperspectral data

    NASA Astrophysics Data System (ADS)

    Yu, Dingfeng; Zhou, Bin; Zhang, Xueqing; Xie, Weihao; Liu, Enxiao

    2015-12-01

    In this study, field data such as secchi depth of th Sishili Bay and its adjacent areas in Yantai's coastal waters were observed, meanwhile, hyperspectral remote snesing data were measured with Ocean Optics USB4000 spectrometer during two cruises carried out on 22nd and 23rd June 2009. The coastal water-leaving refectance of HICO was simulate from in situ hyperspectral remote sensing spectrum with 0.19 nm spectral resolution. According to the spectral simulation, characteristics bands of HICO were identified for water clarity estimation model. On the basis of correlation analysis between water transparency and simulation spectra, a single band model for estimating Secchi depth was established. Moreover, the relationship between Secchi depth band ratios of HICO were analyzed, and then a linear regression model of water clarity using simulated HICO was developed, with a mean relative error of 5.6% and relative mean square error of 0.29 m. The result indicates that the band ratio model of Rrs(507.18)/Rrs(518.64) of HICO could be used to retrieve Secchi depth in coastal waters.

  15. Large Illinoisan shelf-margin channel in the South Timbalier and Ewing Bank areas, offshore Gulf of Mexico

    SciTech Connect

    Ruggiero, R.W.; Bowman, P. )

    1991-03-01

    During an Illinoisan lowstand, a major channel became entrenched on the shelf and deposited deltaic sediment of the shelf-slope break in the South Timbalier and Ewing Bank areas. This shelf-edge delta overloaded the margin, creating a major slope failure. This 'channel,' or slump canyon, which was originally deep and narrow, evolved through retrogradational wasting of the shelf into a broader feature during back-filling and abandonment. Mapping with integrated seismic and well data indicates a feature that is 6 mi wide and has 2300 ft of relief, from the base of the channel to the highest margin. Gravel lag fills the deepest portion of the scour and constitutes an excellent, though restricted, gas reservoir. The limits of the reservoir are defined by mapping of a seismic amplitude anomaly. The balance of the back-fill is comprised of thinly bedded silstone and sandstone sequences that generally thin and fine upward; each is capped by marine shales. The fill geometry is primarily nested or stacked channels. Positive topographic features on the outer shelf tower above the channel floor, either as uneroded remnants or as part of channel margin slump mounds. Sand-prone sediment onlapped these highs, thereby creating numerous stratigraphic traps. As sea level rose, the locus of deposition within the channel shifted progressively shoreward, and the fill was capped by a clean, transgressive shale. Further work is necessary to ascertain the location of the submarine fan far down-dip of this shelf-edge channel. Laterally extensive reservoirs can be expected in more distal depositional environments.

  16. Diving deeper into individual foraging specializations of a large marine predator, the southern sea lion.

    PubMed

    Baylis, A M M; Orben, R A; Arnould, J P Y; Peters, K; Knox, T; Costa, D P; Staniland, I J

    2015-12-01

    Despite global declines in the abundance of marine predators, knowledge of foraging ecology, necessary to predict the ecological consequences of large changes in marine predator abundance, remains enigmatic for many species. Given that populations suffering severe declines are of conservation concern, we examined the foraging ecology of southern sea lions (SSL) (Otaria flavescens)-one of the least studied otariids (fur seal and sea lions)-which have declined by over 90% at the Falkland Islands since the 1930s. Using a combination of biologging devices and stable isotope analysis of vibrissae, we redress major gaps in the knowledge of SSL ecology and quantify patterns of individual specialization. Specifically, we revealed two discrete foraging strategies, these being inshore (coastal) and offshore (outer Patagonian Shelf). The majority of adult female SSL (72% or n = 21 of 29 SSL) foraged offshore. Adult female SSL that foraged offshore travelled further (92 ± 20 vs. 10 ± 4 km) and dived deeper (75 ± 23 vs. 21 ± 8 m) when compared to those that foraged inshore. Stable isotope analysis revealed long-term fidelity (years) to these discrete foraging habitats. In addition, we found further specialization within the offshore group, with adult female SSL separated into two clusters on the basis of benthic or mixed (benthic and pelagic) dive behavior (benthic dive proportion was 76 ± 9 vs. 51 ± 8%, respectively). We suggest that foraging specialization in depleted populations such as SSL breeding at the Falkland Islands, are influenced by foraging site fidelity, and could be independent of intraspecific competition. Finally, the behavioral differences we describe are crucial to understanding population-level dynamics, impediments to population recovery, and threats to population persistence.

  17. Social foragers adopt a riskier foraging mode in the centre of their groups

    PubMed Central

    Beauchamp, Guy

    2013-01-01

    Foraging in groups provides many benefits that are not necessarily experienced the same way by all individuals. I explore the possibility that foraging mode, the way individuals exploit resources, varies as a function of spatial position in the group, reflecting commonly occurring spatial differences in predation risk. I show that semipalmated sandpipers (Calidris pusilla), a social foraging avian species, tended to adopt a riskier foraging mode in the central, more protected areas of their groups. Central birds effectively used the more peripheral group members as sentinels, allowing them to exploit a wider range of resources within the same group at the same time. This finding provides a novel benefit of living in groups, which may have a broad relevance given that social foraging species often exploit a large array of resources. PMID:24108674

  18. Current and future offshore activities in Canada

    SciTech Connect

    Hnatiuk, J.

    1987-06-01

    The development of innovative exploratory drilling systems for Canada's harsh Arctic offshore areas over the past decade and future activity in these areas, including possible production concepts, are discussed. The results can be applied in other Arctic areas of the world, including offshore Alaska. This operating experience will advance technology and serve as a basis for the design of Arctic offshore production and transportation systems. Unique technology has been developed and successfully used in the discovery of major accumulations of hyrodcarbons. Continued technological advances are anticipated to have widespread Arctic applications in both exploratory and production operations.

  19. Utilisation of Intensive Foraging Zones by Female Australian Fur Seals

    PubMed Central

    Hoskins, Andrew J.; Costa, Daniel P.; Arnould, John P. Y.

    2015-01-01

    Within a heterogeneous environment, animals must efficiently locate and utilise foraging patches. One way animals can achieve this is by increasing residency times in areas where foraging success is highest (area-restricted search). For air-breathing diving predators, increased patch residency times can be achieved by altering both surface movements and diving patterns. The current study aimed to spatially identify the areas where female Australian fur seals allocated the most foraging effort, while simultaneously determining the behavioural changes that occur when they increase their foraging intensity. To achieve this, foraging behaviour was successfully recorded with a FastLoc GPS logger and dive behaviour recorder from 29 individual females provisioning pups. Females travelled an average of 118 ± 50 km from their colony during foraging trips that lasted 7.3 ± 3.4 days. Comparison of two methods for calculating foraging intensity (first-passage time and first-passage time modified to include diving behaviour) determined that, due to extended surface intervals where individuals did not travel, inclusion of diving behaviour into foraging analyses was important for this species. Foraging intensity ‘hot spots’ were found to exist in a mosaic of patches within the Bass Basin, primarily to the south-west of the colony. However, the composition of benthic habitat being targeted remains unclear. When increasing their foraging intensity, individuals tended to perform dives around 148 s or greater, with descent/ascent rates of approximately 1.9 m•s-1 or greater and reduced postdive durations. This suggests individuals were maximising their time within the benthic foraging zone. Furthermore, individuals increased tortuosity and decreased travel speeds while at the surface to maximise their time within a foraging location. These results suggest Australian fur seals will modify both surface movements and diving behaviour to maximise their time within a foraging patch

  20. Utilisation of intensive foraging zones by female Australian fur seals.

    PubMed

    Hoskins, Andrew J; Costa, Daniel P; Arnould, John P Y

    2015-01-01

    Within a heterogeneous environment, animals must efficiently locate and utilise foraging patches. One way animals can achieve this is by increasing residency times in areas where foraging success is highest (area-restricted search). For air-breathing diving predators, increased patch residency times can be achieved by altering both surface movements and diving patterns. The current study aimed to spatially identify the areas where female Australian fur seals allocated the most foraging effort, while simultaneously determining the behavioural changes that occur when they increase their foraging intensity. To achieve this, foraging behaviour was successfully recorded with a FastLoc GPS logger and dive behaviour recorder from 29 individual females provisioning pups. Females travelled an average of 118 ± 50 km from their colony during foraging trips that lasted 7.3 ± 3.4 days. Comparison of two methods for calculating foraging intensity (first-passage time and first-passage time modified to include diving behaviour) determined that, due to extended surface intervals where individuals did not travel, inclusion of diving behaviour into foraging analyses was important for this species. Foraging intensity 'hot spots' were found to exist in a mosaic of patches within the Bass Basin, primarily to the south-west of the colony. However, the composition of benthic habitat being targeted remains unclear. When increasing their foraging intensity, individuals tended to perform dives around 148 s or greater, with descent/ascent rates of approximately 1.9 m•s-1 or greater and reduced postdive durations. This suggests individuals were maximising their time within the benthic foraging zone. Furthermore, individuals increased tortuosity and decreased travel speeds while at the surface to maximise their time within a foraging location. These results suggest Australian fur seals will modify both surface movements and diving behaviour to maximise their time within a foraging patch.

  1. Terrestrial and Marine Foraging Strategies of an Opportunistic Seabird Species Breeding in the Wadden Sea

    PubMed Central

    Schwemmer, Philipp; Paiva, Vitor H.; Corman, Anna-Marie; Fock, Heino O.; Voigt, Christian C.; Adler, Sven

    2016-01-01

    Lesser black-backed gulls Larus fuscus are considered to be mainly pelagic. We assessed the importance of different landscape elements (open sea, tidal flats and inland) by comparing marine and terrestrial foraging behaviours in lesser black-backed gulls breeding along the coast of the southern North Sea. We attached GPS data loggers to eight incubating birds and collected information on diet and habitat use. The loggers recorded data for 10–19 days to allow flight-path reconstruction. Lesser black-backed gulls foraged in both offshore and inland areas, but rarely on tidal flats. Targets and directions were similar among all eight individuals. Foraging trips (n = 108) lasted 0.5–26.4 h (mean 8.7 h), and ranges varied from 3.0–79.9 km (mean 30.9 km). The total distance travelled per foraging trip ranged from 7.5–333.6 km (mean 97.9 km). Trips out to sea were significantly more variable in all parameters than inland trips. Presence in inland areas was closely associated with daylight, whereas trips to sea occurred at day and night, but mostly at night. The most common items in pellets were grass (48%), insects (38%), fish (28%), litter (26%) and earthworms (20%). There was a significant relationship between the carbon and nitrogen isotope signals in blood and the proportional time each individual spent foraging at sea/land. On land, gulls preferentially foraged on bare ground, with significantly higher use of potato fields and significantly less use of grassland. The flight patterns of lesser black-backed gulls at sea overlapped with fishing-vessel distribution, including small beam trawlers fishing for shrimps in coastal waters close to the colony and large beam-trawlers fishing for flatfish at greater distances. Our data show that individuals made intensive use of the anthropogenic landscape and seascape, indicating that lesser black-backed gulls are not a predominantly marine species during the incubation period. PMID:27525661

  2. Prey type and foraging ecology of Sanderlings Calidris alba in different climate zones: are tropical areas more favourable than temperate sites?

    PubMed Central

    Ntiamoa-Baidu, Yaa; Piersma, Theunis; Reneerkens, Jeroen

    2015-01-01

    Sanderlings (Calidris alba) are long-distance migratory shorebirds with a non-breeding range that spans temperate and tropical coastal habitats. Breeding in the High Arctic combined with non-breeding seasons in the tropics necessitate long migrations, which are energetically demanding. On an annual basis, the higher energy expenditures during migration might pay off if food availability in the tropics is higher than at temperate latitudes. We compared foraging behaviour of birds at a north temperate and a tropical non-breeding site in the Netherlands and Ghana, respectively. In both cases the birds used similar habitats (open beaches), and experienced similar periods of daylight, which enabled us to compare food abundance and availability, and behavioural time budgets and food intake. During the non-breeding season, Sanderlings in the Netherlands spent 79% of their day foraging; in Ghana birds spent only 38% of the daytime period foraging and the largest proportion of their time resting (58%). The main prey item in the Netherlands was the soft-bodied polychaete Scolelepis squamata, while Sanderlings in Ghana fed almost exclusively on the bivalve Donax pulchellus, which they swallowed whole and crushed internally. Average availability of polychaete worms in the Netherlands was 7.4 g ash free dry mass (AFDM) m−2, which was one tenth of the 77.1 g AFDM m−2 estimated for the beach in Ghana. In the tropical environment of Ghana the Sanderlings combined relatively low energy requirements with high prey intake rates (1.64 mg opposed to 0.13 mg AFDM s−1 for Ghana and the Netherlands respectively). Although this may suggest that the Ghana beaches are the most favourable environment, processing the hard-shelled bivalve (D. pulchellus) which is the staple food could be costly. The large amount of daytime spent resting in Ghana may be indicative of the time needed to process the shell fragments, rather than indicate rest. PMID:26290790

  3. Pioneering offshore excellence

    SciTech Connect

    Kent, R.P.; Grattan, L.

    1996-11-01

    Hibernia Management and Development Company Ltd. (HMDC) was formed in 1990 by a consortium of oil companies to develop their interests in the Hibernia and Avalon reservoirs offshore Newfoundland in a safe and environmentally responsible manner. The reservoirs are located 315km ESE of St. John`s in the North Atlantic. The water depth is about 80m. The entire Hibernia field is estimated to contain more than three billion barrels of oil in place and the owners development plan area is estimated to contain two billion barrels. Recoverable reserves are estimated to be approximately 615 million barrels. The Hibernia reservoir, the principle reservoir, is located at an average depth of 3,700m. HMDC is building a large concrete gravity based structure (GBS) that which will support the platform drilling and processing facilities and living quarters for 280 personnel. In 1997 the platform will be towed to the production site and production will commence late 1997. Oil will be exported by a 2 km long pipeline to an offshore loading system. Dynamically positioned tankers will then take the oil to market. Average daily production is expected to plateau between 125,000 and 135,000 BOPD. It will be the first major development on the east coast of Canada and is located in an area that is prone to pack ice and icebergs.

  4. Fine scale bio-physical oceanographic characteristics predict the foraging occurrence of contrasting seabird species; Gannet (Morus bassanus) and storm petrel (Hydrobates pelagicus)

    NASA Astrophysics Data System (ADS)

    Scott, B. E.; Webb, A.; Palmer, M. R.; Embling, C. B.; Sharples, J.

    2013-10-01

    As we begin to manage our oceans in much more spatial detail we must understand a great deal more about oceanographic habitat preferences of marine mobile top predators. In this unique field study we test a hypothesis on the mechanisms defining mobile predator foraging habitat characteristics by comparing temporally and spatially detailed bio-physical oceanographic data from contrasting topographical locations. We contrast the foraging locations of two very different seabird species, gannets and storm petrels, by repeatedly sampling a bank and a nearby flat area over daily tidal cycles during spring and neap tides. The results suggest that storm petrels are linked to foraging in specific locations where internal waves are produced, which is mainly on banks. These locations can also include the presence of high biomass of chlorophyll. In contrast, the location where more gannets are foraging is significantly influenced by temporal variables with higher densities of foraging birds much more likely during the neap tide than times of spring tide. The foraging times of both species was influenced by differences between the vertical layers of the water column above and below the thermocline; via either vertical shear of horizontal currents or absolute differences in speed between layers. Higher densities of foraging gannets were significantly more likely to be found at ebb tides in both bank and flat regions however over the bank, the density of foraging gannets was higher when the differences in speed between the layers were at a maximum. Both gannets and storm petrels appear to be more likely to forage when wind direction is opposed to tidal direction. This detailed understanding links foraging behaviour to predictable spatial and temporal bio-physical vertical characteristics and thus can be immediately used to explain variance and increase certainty in past abundance and distributional surveys. These results also illuminate the types of variables that should be

  5. Sea floor topography and backscatter intensity of the Historic Area Remediation Site (HARS), offshore of New York, based on multibeam surveys conducted in 1996, 1998, and 2000

    USGS Publications Warehouse

    Butman, Bradford; Danforth, W.W.; Knowles, S.C.; May, Brian; Serrett, Laurie

    2000-01-01

    An area offshore of Sandy Hook, New Jersey, has been used extensively for disposal of dredged and other materials, derived from the New York/New Jersey Harbor and surrounding areas, since the late 1800's (Figure 1). Between 1976 and 1995, the New York Bight Dredged Material Disposal Site, also known as the Mud Dump Site (Figure 2), received on average about 6 million cubic yards of material each year from federal and private maintenance dredging and from harbor deepening activities (Massa and others, 1996). In September 1997 the Mud Dump Site (MDS) was closed as an official ocean disposal site by the U.S. Environmental Protection Agency (http://www.epa.gov/), and the MDS and surrounding areas were designated as the Historic Area Remediation Site (HARS). The HARS is subdivided into a Primary Remediation Area (PRA, subdivided into 9 cells), a Buffer Zone, and a No-Discharge Zone (Figure 2). The sea floor of the HARS, approximately 9 square nautical miles in area, is being remediated by placing at least a one-meter cap of Category I (clean) dredged material on top of the existing surface sediments that exhibit varying degrees of degradation. (See http://www.nan.usace.army.mil/business/prjlinks/dmmp/benefic/hars.htm)(Category I sediments have no potential short or long-term impacts and are acceptable for unrestricted ocean disposal (EPA, 1996)). About 1.1 million cubic yards of dredged material for remediation was placed in the HARS in 1999, and 2.5 million cubic yards in 2000. Three multibeam echosounder surveys were carried out to map the topography and surficial geology of the HARS. The surveys were conducted November 23 - December 3, 1996, October 26 - November 11, 1998, and April 6 - 30, 2000. The surveys were carried out as part of a larger survey of the Hudson Shelf Valley and adjacent shelf (Butman and others, 1998, (http://pubs.usgs.gov/openfile/of98-616/). This report presents maps showing topography, shaded relief, and backscatter intensity (a measure of sea

  6. Aggressive and foraging behavioral interactions among ruffe

    USGS Publications Warehouse

    Savino, Jacqueline F.; Kostich, Melissa J.

    2000-01-01

    The ruffe, Gymnocephalus cernuus, is a nonindigenous percid in the Great Lakes. Ruffe are aggressive benthivores and forage over soft substrates. Laboratory studies in pools (100 cm in diameter, 15 cm water depth) were conducted to determine whether fish density (low = 2, medium = 4, high = 6 ruffe per pool) changed foraging and aggressive behaviors with a limited food supply of chironomid larvae. All fish densities demonstrated a hierarchy based on aggressive interactions, but ruffe were most aggressive at low and high fish densities. Time spent in foraging was lowest at the low fish density. The best forager at the low fish density was the most aggressive individual, but the second most aggressive fish at the medium and high fish density was the best forager and also the one chased most frequently. A medium fish density offered the best energetic benefits to ruffe by providing the lowest ratio of time spent in aggression to that spent foraging. Based on our results, ruffe should grow best at an intermediate density. With high ruffe densities, we would also expect disparity in size as the more aggressive fish are able to garner a disproportionate amount of the resources. Alternatively, as the Great Lakes are a fairly open system, ruffe could migrate out of one area to colonize another as populations exceed optimal densities.

  7. Foraging Experiences with Children

    ERIC Educational Resources Information Center

    Russell, Helen Ross

    1976-01-01

    Provided are foraging experiences and wild foods information for utilization in the urban school curriculum. Food uses are detailed for roses, dandelions, wild onions, acorns, cattails, violets and mints. (BT)

  8. Foraging search: Prototypical intelligence

    NASA Astrophysics Data System (ADS)

    Mobus, George

    2000-05-01

    We think because we eat. Or as Descartes might have said, on a little more reflection, "I need to eat, therefore I think." Animals that forage for a living repeatedly face the problem of searching for a sparsely distributed resource in a vast space. Furthermore, the resource may occur sporadically and episodically under conditions of true uncertainty (nonstationary, complex and non-linear dynamics). I assert that this problem is the canonical problem solved by intelligence. It's solution is the basis for the evolution of more advanced intelligence in which the space of search includes that of concepts (objects and relations) encoded in cortical structures. In humans the conscious experience of searching through concept space we call thinking. The foraging search model is based upon a higher-order autopoeitic system (the forager) employing anticipatory processing to enhance its success at finding food while avoiding becoming food or having accidents in a hostile world. I present a semi-formal description of the general foraging search problem and an approach to its solution. The latter is a brain-like structure employing dynamically adaptive neurons. A physical robot, MAVRIC, embodies some principles of foraging. It learns cues that lead to improvements in finding targets in a dynamic and nonstationary environment. This capability is based on a unique learning mechanism that encodes causal relations in the neural-like processing element. An argument is advanced that searching for resources in the physical world, as per the foraging model, is a prototype for generalized search for conceptual resources as when we think. A problem represents a conceptual disturbance in a homeostatic sense. The finding of a solution restores the homeostatic balance. The establishment of links between conceptual cues and solutions (resources) and the later use of those cues to think through to solutions of quasi-isomorphic problems is, essentially, foraging for ideas. It is a quite

  9. An integrated approch to the foraging ecology of marine birds and mammals

    NASA Astrophysics Data System (ADS)

    Croll, Donald A.; Tershy, Bernie R.; Hewitt, Roger P.; Demer, David A.; Fiedler, Paul C.; Smith, Susan E.; Armstrong, Wesley; Popp, Jacqueline M.; Kiekhefer, Thomas; Lopez, Vanesa R.; Urban, Jorge; Gendron, Diane

    Birds and mammals are important components of pelagic marine ecosystems, but our knowledge of their foraging ecology is limited. We distinguish six distinct types of data that can be used in various combinations to understand their foraging behavior and ecology. We describe methods that combine concurrent dive recorder deployment, oceanographic sampling, and hydroacoustic surveys to generate hypotheses about interactions between the physical environment and the distribution, abundance, and behavior of pelagic predators and their prey. Our approach is to (1) map the distribution of whales in relation to the distribution of their prey and the physical features of the study area (bottom topography, temperature, and salinity); and (2) measure the foraging behavior and diet of instrumented whales in the context of the fine-scale distribution and composition of their prey and the physical environment. We use this approach to demonstrate a relationship between blue whale distribution, sea surface temperature, and concentrations of their euphausiid prey at different spatial scales offshore of the Channel Islands, California. Blue whale horizontal spatial distribution was correlated with regions of high acoustic backscatter. Blue whale dive depths closely tracked the depth distribution of krill. Net sampling and whale diet revealed that whales fed exclusively upon dense schools of Euphausia pacifica (between 100 and 200 m) and Thysanoessa spinifera (from the surface to 100 m). Whales concentrated foraging efforts upon those dense euphausiid schools that form downstream from an upwelling center in close proximity to regions of steep topographic relief. We propose that (1) the distribution of Balaenoptera whales in the coastal California Current region is defined by their attraction to areas of predictably high prey density; (2) the preferred prey of these whales are several species of euphausiids ( E. pacifica, T. spinifera, and N. simplex) that are abundant in the

  10. Walrus areas of use in the Chukchi Sea during sparse sea ice cover

    USGS Publications Warehouse

    Jay, Chadwick V.; Fischbach, Anthony S.; Kochnev, Anatoly A.

    2012-01-01

    The Pacific walrus Odobenus rosmarus divergens feeds on benthic invertebrates on the continental shelf of the Chukchi and Bering Seas and rests on sea ice between foraging trips. With climate warming, ice-free periods in the Chukchi Sea have increased and are projected to increase further in frequency and duration. We radio-tracked walruses to estimate areas of walrus foraging and occupancy in the Chukchi Sea from June to November of 2008 to 2011, years when sea ice was sparse over the continental shelf in comparison to historical records. The earlier and more extensive sea ice retreat in June to September, and delayed freeze-up of sea ice in October to November, created conditions for walruses to arrive earlier and stay later in the Chukchi Sea than in the past. The lack of sea ice over the continental shelf from September to October caused walruses to forage in nearshore areas instead of offshore areas as in the past. Walruses did not frequent the deep waters of the Arctic Basin when sea ice retreated off the shelf. Walruses foraged in most areas they occupied, and areas of concentrated foraging generally corresponded to regions of high benthic biomass, such as in the northeastern (Hanna Shoal) and southwestern Chukchi Sea. A notable exception was the occurrence of concentrated foraging in a nearshore area of northwestern Alaska that is apparently depauperate in walrus prey. With increasing sea ice loss, it is likely that walruses will increase their use of coastal haul-outs and nearshore foraging areas, with consequences to the population that are yet to be understood.

  11. Offshore wind farm layout optimization

    NASA Astrophysics Data System (ADS)

    Elkinton, Christopher Neil

    the farm. A more thorough optimization highlighted the features of the area that would result in a minimized COE. The results showed reasonable layout designs and COE estimates that are consistent with existing offshore wind farms.

  12. Offshore Wind Energy Systems Engineering Curriculum Development

    SciTech Connect

    McGowan, Jon G.; Manwell, James F.; Lackner, Matthew A.

    2012-12-31

    Utility-scale electricity produced from offshore wind farms has the potential to contribute significantly to the energy production of the United States. In order for the U.S. to rapidly develop these abundant resources, knowledgeable scientists and engineers with sound understanding of offshore wind energy systems are critical. This report summarizes the development of an upper-level engineering course in "Offshore Wind Energy Systems Engineering." This course is designed to provide students with a comprehensive knowledge of both the technical challenges of offshore wind energy and the practical regulatory, permitting, and planning aspects of developing offshore wind farms in the U.S. This course was offered on a pilot basis in 2011 at the University of Massachusetts and the National Renewable Energy Laboratory (NREL), TU Delft, and GL Garrad Hassan have reviewed its content. As summarized in this report, the course consists of 17 separate topic areas emphasizing appropriate engineering fundamentals as well as development, planning, and regulatory issues. In addition to the course summary, the report gives the details of a public Internet site where references and related course material can be obtained. This course will fill a pressing need for the education and training of the U.S. workforce in this critically important area. Fundamentally, this course will be unique due to two attributes: an emphasis on the engineering and technical aspects of offshore wind energy systems, and a focus on offshore wind energy issues specific to the United States.

  13. 7 CFR 407.13 - Group risk plan for forage.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    .... Definitions Harvest. Removal of the forage from the field, and rotational grazing. NASS yield. The yield... method appropriate for forage, into a properly prepared seedbed. Rotational grazing. The defoliation of... smaller parcels and livestock are moved from one area to another, allowing a period of grazing followed...

  14. 7 CFR 407.13 - Group risk plan for forage.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    .... Definitions Harvest. Removal of the forage from the field, and rotational grazing. NASS yield. The yield... method appropriate for forage, into a properly prepared seedbed. Rotational grazing. The defoliation of... smaller parcels and livestock are moved from one area to another, allowing a period of grazing followed...

  15. 7 CFR 407.13 - Group risk plan for forage.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .... Definitions Harvest. Removal of the forage from the field, and rotational grazing. NASS yield. The yield... method appropriate for forage, into a properly prepared seedbed. Rotational grazing. The defoliation of... smaller parcels and livestock are moved from one area to another, allowing a period of grazing followed...

  16. 7 CFR 407.13 - Group risk plan for forage.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    .... Definitions Harvest. Removal of the forage from the field, and rotational grazing. NASS yield. The yield... method appropriate for forage, into a properly prepared seedbed. Rotational grazing. The defoliation of... smaller parcels and livestock are moved from one area to another, allowing a period of grazing followed...

  17. Animal Foraging and the Evolution of Goal-Directed Cognition

    ERIC Educational Resources Information Center

    Hills, Thomas T.

    2006-01-01

    Foraging-and feeding-related behaviors across eumetazoans share similar molecular mechanisms, suggesting the early evolution of an optimal foraging behavior called area-restricted search (ARS), involving mechanisms of dopamine and glutamate in the modulation of behavioral focus. Similar mechanisms in the vertebrate basal ganglia control motor…

  18. Offshore drilling to increase in 1984

    SciTech Connect

    Not Available

    1984-05-01

    A mid-year report presents a worldwide overview of offshore drilling operations. The Gulf of Mexico and the North Sea are posting substantial gains as companies rush to drill the millions of acres acquired in those sectors both last year and in previous offerings. The Middle East, Latin America and the Asia/Pacific offshore theaters will see only slight increases. The Mediterranean and African regions are expected to sustain declines. A region-by-region summary of the 1984 offshore forecast is presented showing exploration and appraisal activities, as well as development for all of these areas.

  19. Certification of offshore mooring steel wire ropes

    SciTech Connect

    Lohne, P.W.

    1996-12-31

    The trend to produce oil in increasingly deeper water has led to the development of floating production solutions for the exploitation of the energy resources in these areas. It is a fact that steel wire ropes have been used and are being proposed as line segments in the majority of the mooring systems of these units/ships. This paper specifies requirements for the materials, design, manufacture and testing of large diameter offshore mooring steel wire ropes and may serve as a technical reference document in contractual matters between the purchaser and the manufacturer. Typical applications covered are permanently moored floating production systems (FPS), offshore loading systems and mobile offshore units.

  20. Offshore oil in the Alaskan Arctic

    NASA Technical Reports Server (NTRS)

    Weeks, W. F.; Weller, G.

    1984-01-01

    Oil and gas deposits in the Alaskan Arctic are estimated to contain up to 40 percent of the remaining undiscovered crude oil and oil-equivalent natural gas within U.S. jurisdiction. Most (65 to 70 percent) of these estimated reserves are believed to occuur offshore beneath the shallow, ice-covered seas of the Alaskan continental shelf. Offshore recovery operations for such areas are far from routine, with the primary problems associated with the presence of ice. Some problems that must be resolved if efficient, cost-effective, environmentally safe, year-round offshore production is to be achieved include the accurate estimation of ice forces on offshore structures, the proper placement of pipelines beneath ice-produced gouges in the sea floor, and the cleanup of oil spills in pack ice areas.

  1. Offshore oil in the alaskan arctic.

    PubMed

    Weeks, W F; Weller, G

    1984-07-27

    Oil and gas deposits in the Alaskan Arctic are estimated to contain up to 40 percent of the remaining undiscovered crude oil and oil-equivalent nature gas within U.S. jurisdiction. Most (65 to 70 percent) of these estimated reserves are believed to occur offshore beneath the shallow, ice-covered seas, of the Alaskan continental shelf. Offshore recovery operations for such areas are far from routine, with the primary problems associated with the presence of ice. Some problems that must be resolved if efficient, cost-effective, environmentally safe, year-round offshore production is to be achieved include the accurate estimation of ice forces on offshore structures, the proper placement of pipelines beneath ice-produced gouges in the sea floor, and the cleanup of oil spills in pack ice areas.

  2. Application of a rising plate meter to estimate forage yield on dairy farms in Pennsylvania

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurately assessing pasture forage yield is necessary for producers who want to budget feed expenses and make informed pasture management decisions. Clipping and weighing forage from a known area is a direct method to measure pasture forage yield, however it is time consuming. The rising plate mete...

  3. Mapping of wood stork foraging habitat with satellite data

    SciTech Connect

    Jensen, J.R.; Coulter, M.; Mackey, H.E. Jr.; Hodgson, M.E.

    1985-01-01

    Potential foraging sites for an endangered species, the wood stork, were identified using Landsat thematic mapper data for a section of north central Georgia and the Savannah River floodplain swamp in South Carolina. This was accomplished using innovative clustering techniques applied to known wood stork foraging sites around the Birdsville Colony in Georgia. The signatures for known sites were then geographically extended to a 1520-square-kilometer region surrounding the Birdsville Colony. Thematic maps were produced and foraging area acreages computed providing a regional assessment of existing and potential wood stork foraging sites. Approximately 1744 hectarea of potential shallow water and macrophyte foraging habitat were identified in the area surroundings the Birdsville Colony. 14 refs., 3 figs.

  4. The Physics of Foraging

    NASA Astrophysics Data System (ADS)

    Viswanathan, Gandhimohan. M.; da Luz, Marcos G. E.; Raposo, Ernesto P.; Stanley, H. Eugene

    2011-06-01

    Part I. Introduction: Movement: 1. Empirical motivation for studying movement; 2. Statistical physics of biological motion; 3. Random walks and Lévy flights; 4. Wandering albatrosses; Part II. Experimental Findings: 5. Early studies; 6. Evidence of anomalous diffusion; 7. Human dispersal; 8. How strong is the evidence?; Part III. Theory of Foraging: 9. Optimizing encounter rates; 10. Lévy flight foraging; 11. Other search models; Part IV. Finale: A Broader Context: 12. Superdiffusive random searches; 13. Adaptational versus emergent superdiffusion; 14. Perspectives and open problems; Appendices; References; Index.

  5. Temporal effects of hunting on foraging behavior of an apex predator: Do bears forego foraging when risk is high?

    PubMed

    Hertel, Anne G; Zedrosser, Andreas; Mysterud, Atle; Støen, Ole-Gunnar; Steyaert, Sam M J G; Swenson, Jon E

    2016-12-01

    Avoiding predators most often entails a food cost. For the Scandinavian brown bear (Ursus arctos), the hunting season coincides with the period of hyperphagia. Hunting mortality risk is not uniformly distributed throughout the day, but peaks in the early morning hours. As bears must increase mass for winter survival, they should be sensitive to temporal allocation of antipredator responses to periods of highest risk. We expected bears to reduce foraging activity at the expense of food intake in the morning hours when risk was high, but not in the afternoon, when risk was low. We used fine-scale GPS-derived activity patterns during the 2 weeks before and after the onset of the annual bear hunting season. At locations of probable foraging, we assessed abundance and sugar content, of bilberry (Vaccinium myrtillus), the most important autumn food resource for bears in this area. Bears decreased their foraging activity in the morning hours of the hunting season. Likewise, they foraged less efficiently and on poorer quality berries in the morning. Neither of our foraging measures were affected by hunting in the afternoon foraging bout, indicating that bears did not allocate antipredator behavior to times of comparably lower risk. Bears effectively responded to variation in risk on the scale of hours. This entailed a measurable foraging cost. The additive effect of reduced foraging activity, reduced forage intake, and lower quality food may result in poorer body condition upon den entry and may ultimately reduce reproductive success.

  6. Redesigning forages with condensed tannins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maximizing protein content in forages and minimizing protein loss during silage fermentation and rumen digestion are concerns for livestock and dairy producers. Substantial amounts of forage protein undergo proteolysis (breakdown) during the ensiling process and during rumen fermentation, transforme...

  7. New Developments in Forage Varieties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Forage crops harvested for hay or haylage or grazed support dairy, beef, sheep and horse production. Additional livestock production from reduced forage acreage supports the need for forage variety improvement. The Consortium for Alfalfa Improvement is a partnership model of government, private no...

  8. Optimal Foraging in Semantic Memory

    ERIC Educational Resources Information Center

    Hills, Thomas T.; Jones, Michael N.; Todd, Peter M.

    2012-01-01

    Do humans search in memory using dynamic local-to-global search strategies similar to those that animals use to forage between patches in space? If so, do their dynamic memory search policies correspond to optimal foraging strategies seen for spatial foraging? Results from a number of fields suggest these possibilities, including the shared…

  9. How dangerous is offshore drilling

    SciTech Connect

    McIntosh, T.S.

    1981-08-01

    As concluded by the National Research Council, the frequency of injuries during oil and gas operations on the outer continental shelf is comparable to that in other industries such as mining, maritime service, and heavy construction. Although an area of concern, offshore safety is not easily improved by legislation or detailed regulation. The industry itself must be committed to providing the safest possible workplace for the job and the environment. At Zapata Off-Shore Co., for example, top management recognizes the value of safety-trained personnel in terms of not only decreased downtime and lower insurance costs but also improved crew morale and productivity. The key operatives of Zapata's program are the rig representatives who provide full-time, rig-based safety, training, administrative, and employee-relations assistance to the crews.

  10. 26th Annual offshore technology conference: 1994 Proceedings

    SciTech Connect

    Not Available

    1994-01-01

    This conference represents the world's largest and most comprehensive technical conference and exhibition on offshore resource development. The four proceedings volumes have been separated by major areas of interest with this volume containing papers relative to design of offshore platforms and marine riser systems. Papers deal with design, installation, fabrication, transport systems, mooring devices, repair methods, and development of satellite production facilities. Case histories on various offshore oil and gas fills are discussed along with economics of some applications and designs.

  11. 77 FR 71607 - Mobile Offshore Drilling Unit (MODU) Electrical Equipment Certification Guidance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-03

    ... independent third party lab. The Coast Guard believes that certification of electrical equipment intended for... SECURITY Coast Guard Mobile Offshore Drilling Unit (MODU) Electrical Equipment Certification Guidance... regarding electrical equipment installed in hazardous areas on foreign-flagged Mobile Offshore...

  12. Comparative sucrose responsiveness in Apis mellifera and A. cerana foragers.

    PubMed

    Yang, Wenchao; Kuang, Haiou; Wang, Shanshan; Wang, Jie; Liu, Wei; Wu, Zhenhong; Tian, Yuanyuan; Huang, Zachary Y; Miao, Xiaoqing

    2013-01-01

    In the European honey bee, Apis mellifera, pollen foragers have a higher sucrose responsiveness than nectar foragers when tested using a proboscis extension response (PER) assay. In addition, Africanized honey bees have a higher sucrose responsiveness than European honey bees. Based on the biology of the Eastern honey bee, A. cerana, we hypothesized that A. cerana should also have a higher responsiveness to sucrose than A. mellifera. To test this hypothesis, we compared the sucrose thresholds of pollen foragers and nectar foragers in both A. cerana and A. mellifera in Fujian Province, China. Pollen foragers were more responsive to sucrose than nectar foragers in both species, consistent with previous studies. However, contrary to our hypothesis, A. mellifera was more responsive than A. cerana. We also demonstrated that this higher sucrose responsiveness in A. mellifera was not due to differences in the colony environment by co-fostering two species of bees in the same mixed-species colonies. Because A. mellifera foragers were more responsive to sucrose, we predicted that their nectar foragers should bring in less concentrated nectar compared to that of A. cerana. However, we found no differences between the two species. We conclude that A. cerana shows a different pattern in sucrose responsiveness from that of Africanized bees. There may be other mechanisms that enable A. cerana to perform well in areas with sparse nectar resources.

  13. Polychlorinated biphenyls and organochlorine pesticides as intrinsic tracer tags of foraging grounds of bluefin tuna in the northwest Atlantic Ocean.

    PubMed

    Deshpande, Ashok D; Dickhut, Rebecca M; Dockum, Bruce W; Brill, Richard W; Farrington, Cameron

    2016-04-15

    from offshore Virginia, Gulf of Maine, and Nova Scotia could have had extended residences and foraging within the areas of capture to be able to sustain the stable signatures of PCB congeners. The DFA cluster results supported the concept of metapopulation theory of spatial ecology comprising discrete aggregates of local populations of bluefin tuna where the desired prey species are likely to be abundant. Despite their highly migratory trait and endothermic advantage of foraging in broader and colder habitats, the movements and mixing across the aggregation ranges related to feeding did not appear to be extensive. Advancement in the understanding of bluefin tuna population dynamics beyond the coarse concept of trans-Atlantic migrations to the metapopulation hypothesis provides a novel exploratory tool in the stock assessment and resource management. As the chemical tracer tags are fortified naturally and document the time- and space-integrated foraging history, they promise to serve as the low-cost alternatives to the high-cost electronic data recording tags employed for addressing the migratory movements of bluefin tuna. Between the different potential chemical tracer tags, a distinct advantage of PCB/pesticide analysis over the otolith micro-constituent analysis is that the muscle tissue of a given individual bluefin tuna can be sampled repeatedly for PCB/pesticide analysis over different spatial and temporal scales in a non-lethal manner.

  14. Current and future offshore activities in Canada

    SciTech Connect

    Hnatiuk, J.

    1984-05-01

    The development of innovative exploratory drilling systems for Canada's harsh Arctic offshore areas over the past decade is described. Future activity in these areas, including possible production concepts, is also discussed. The results of the experience in Canadian waters can be applied in other Arctic areas of the world including offshore Alaska. This operating experience will serve to further advance the drilling technology and will serve as a basis for the design of Arctic offshore production and transportation systems. Artificial islands, first commenced in 1972, are still being constructed but with improved designs and equipment. A step forward has been the use of subsea berms on which concrete or steel segmented caissons have been placed. Integrated-type steel caissons have also been adapted for placement on subsea berms, one of which is half of a crude oil tanker and a second, a purpose-built steel caisson to be placed this summer.

  15. Session: Offshore wind

    SciTech Connect

    Gaarde, Jette; Ram, Bonnie

    2004-09-01

    This session at the Wind Energy and Birds/Bats workshop consisted of two presentations. Due to time constraints, a discussion period was not possible. The session addressed the current state of offshore wind energy development. The first presentation ''Monitoring Program and Results: Horns Rev and Nysted'' by Jette Gaarde summarized selected environmental studies conducted to date at operating offshore wind turbine projects in Denmark and lessons from other offshore wind developments in Europe. Wildlife impacts studies from the Danish sites focused on birds, fish, and mammals. The second presentation ''What has the U.S. Wind Industry Learned from the European Example'' by Bonnie Ram provided an update on current permit applications for offshore wind developments in the U.S. as well as lessons that may be drawn from the European experience.

  16. The Organization of Foraging in the Fire Ant, Solenopsis invicta

    PubMed Central

    Tschinkel, Walter R.

    2011-01-01

    Although natural selection in ants acts most strongly at the colony, or superorganismal level, foraging patterns have rarely been studied at that level, focusing instead on the behavior of individual foragers or groups of foragers. The experiments and observations in this paper reveal in broad strokes how colonies of the fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), allocate their available labor to foraging, how they disperse that force within their territory, and how this force changes with colony size, season and worker age. Territory area is positively related to colony size and the number of foragers, more so during the spring than fall. Changes of colony size and territory area are driven by seasonal variation of sexual and worker production, which in turn drive seasonal variation of worker age-distribution. During spring sexual production, colonies shrink because worker production falls below replacement. This loss is proportional to colony size, causing forager density in the spring to be negatively related to colony and territory size. In the fall, colonies emphasize worker production, bringing colony size back up. However, because smaller colonies curtailed spring worker production less than larger ones, their fall forager populations are proportionally greater, causing them to gain territory at the expense of large colonies. Much variation of territory area remains unexplained and can probably be attributed to pressure from neighboring colonies. Boundaries between territories are characterized by “no ants' zones” mostly devoid of fire ants. The forager population can be divided into a younger group of recruitable workers that wait for scouts to activate them to help retrieve large food finds. About one-third of the recruits wait near openings in the foraging tunnels that underlie the entire territory, while two-thirds wait in the nest. Recruitment to food is initially very rapid and local from the foraging tunnels, while sustained

  17. The organization of foraging in the fire ant, Solenopsis invicta.

    PubMed

    Tschinkel, Walter R

    2011-01-01

    Although natural selection in ants acts most strongly at the colony, or superorganismal level, foraging patterns have rarely been studied at that level, focusing instead on the behavior of individual foragers or groups of foragers. The experiments and observations in this paper reveal in broad strokes how colonies of the fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), allocate their available labor to foraging, how they disperse that force within their territory, and how this force changes with colony size, season and worker age. Territory area is positively related to colony size and the number of foragers, more so during the spring than fall. Changes of colony size and territory area are driven by seasonal variation of sexual and worker production, which in turn drive seasonal variation of worker age-distribution. During spring sexual production, colonies shrink because worker production falls below replacement. This loss is proportional to colony size, causing forager density in the spring to be negatively related to colony and territory size. In the fall, colonies emphasize worker production, bringing colony size back up. However, because smaller colonies curtailed spring worker production less than larger ones, their fall forager populations are proportionally greater, causing them to gain territory at the expense of large colonies. Much variation of territory area remains unexplained and can probably be attributed to pressure from neighboring colonies. Boundaries between territories are characterized by "no ants' zones" mostly devoid of fire ants. The forager population can be divided into a younger group of recruitable workers that wait for scouts to activate them to help retrieve large food finds. About one-third of the recruits wait near openings in the foraging tunnels that underlie the entire territory, while two-thirds wait in the nest. Recruitment to food is initially very rapid and local from the foraging tunnels, while sustained

  18. Diet niches of major forage fish in Lake Michigan

    USGS Publications Warehouse

    Davis, B.M.; Savino, J.F.; Ogilvie, L.M.; ,

    2007-01-01

    A large complex of coregonine species historically dominated the fish community of Lake Michigan. The current species complex is simplified with one remaining coregonine, bloater (Coregonus hoyi), deepwater sculpin (Myoxocephalus thompsoni), slimy sculpin (Cottus cognatus), and two dominant invaders, alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax). To better understand the diet relationships of the major offshore forage fishes now in Lake Michigan, diets of bloater, alewife, rainbow smelt, deepwater sculpin, and slimy sculpin were compared. The three sites, chosen to represent northern, central, and southern components of the lake, were sampled during spring, summer, and fall in 1994, and spring and fall in 1995. Forage fishes had diverse and variable diets, with niches differentiated by prey type or location. Diporeia hoyi, Mysis relicta, and zooplankton were the major diet items. The index of relative importance showed benthic (slimy and deepwater sculpins) and pelagic (alewife, rainbow smelt) feeding strategies with opportunistic bloaters incorporating both feeding strategies. Highest diet overlaps were between species of sculpin, and between large and small bloaters; both groups partitioned food by size. Though competition for food may be minimized by spatial segregation of potential competitors, the forage fish in Lake Michigan apparently partition food resources. Fishery management models incorporating food habits of pelagic forage fish would need to take into account diet variation associated with location and season. ?? 2007 E. Schweizerbart'sche Verlagsbuchhandlung.

  19. Offshore Wind Energy

    SciTech Connect

    Strach-Sonsalla, Mareike; Stammler, Matthias; Wenske, Jan; Jonkman, Jason; Vorpahl, Fabian

    2016-07-27

    In 1991, the Vindeby Offshore Wind Farm, the first offshore wind farm in the world, started feeding electricity to the grid off the coast of Lolland, Denmark. Since then, offshore wind energy has developed from this early experiment to a multibillion dollar market and an important pillar of worldwide renewable energy production. Unit sizes grew from 450 kW at Vindeby to the 7.5 MW-class offshore wind turbines (OWT ) that are currently (by October 2014) in the prototyping phase. This chapter gives an overview of the state of the art in offshore wind turbine (OWT) technology and introduces the principles of modeling and simulating an OWT. The OWT components -- including the rotor, nacelle, support structure, control system, and power electronics -- are introduced, and current technological challenges are presented. The OWT system dynamics and the environment (wind and ocean waves) are described from the perspective of OWT modelers and designers. Finally, an outlook on future technology is provided. The descriptions in this chapter are focused on a single OWT -- more precisely, a horizontal-axis wind turbine -- as a dynamic system. Offshore wind farms and wind farm effects are not described in detail in this chapter, but an introduction and further references are given.

  20. Structural features offshore northern Taiwan

    NASA Astrophysics Data System (ADS)

    Yicheng Yang, Eason; Liu, Char-Shine; Chang, Jih-Hsin; Chiu, Chien-Hsuan

    2016-04-01

    The area offshore northern Taiwan is the place where East China Sea Shelf extends into the Southern Okinawa Trough, and where pre-Pleistocene arc-continental collision had occurred. Comparison between fault distribution in the area with previously published results suggests that the fault distribution and regional structural framework are still controversial. Using marine multichannel seismic reflection data collected in 3 marine geophysical survey cruises, we remapped the fault distribution in the northern offshore area of Taiwan. By analyzing all the seismic profiles using the KINGDOM suite (a seismic interpretation software), a new fault distribution map is presented, and a subsurface unconformity PRSB (Pliocene reflection sequence boundary) is identified. Six major NE-SW trending high-angle normal faults cut the PRSB can be traced to the fault systems on land northernmost Taiwan. These normal faults are located between the Southern Okinawa Trough and the East China Sea continental shelf basin, and have been suggested to be reactivated from pre-existing reverse faults. The offsets of fault ramps in PRSB increase toward southeast. The isopach map of the study area compiled shows that sediment strata overlying PRSB thin toward northwest.

  1. Food availability and foraging near human developments by black bears

    USGS Publications Warehouse

    Merkle, Jerod A.; Robinson, Hugh S.; Krausman, Paul R.; Alaback, Paul B.

    2013-01-01

    Understanding the relationship between foraging ecology and the presence of human-dominated landscapes is important, particularly for American black bears (Ursus americanus), which sometimes move between wildlands and urban areas to forage. The food-related factors influencing this movement have not been explored, but can be important for understanding the benefits and costs to black bear foraging behavior and the fundamental origins of bear conflicts. We tested whether the scarcity of wildland foods or the availability of urban foods can explain when black bears forage near houses, examined the extent to which male bears use urban areas in comparison to females, and identified the most important food items influencing bear movement into urban areas. We monitored 16 collared black bears in and around Missoula, Montana, during 2009 and 2010, while quantifying the rate of change in green vegetation and the availability of 5 native berry-producing species outside the urban area, the rate of change in green vegetation, and the availability of apples and garbage inside the urban area. We used parametric time-to-event models in which an event was a bear location collected within 100 m of a house. We also visited feeding sites located near houses and quantified food items bears had eaten. The probability of a bear being located near a house was 1.6 times higher for males, and increased during apple season and the urban green-up. Fruit trees accounted for most of the forage items at urban feeding sites (49%), whereas wildland foods composed <10%. Black bears foraged on human foods near houses even when wildland foods were available, suggesting that the absence of wildland foods may not influence the probability of bears foraging near houses. Additionally, other attractants, in this case fruit trees, appear to be more important than the availability of garbage in influencing when bears forage near houses.

  2. Learning foraging thresholds for lizards

    SciTech Connect

    Goldberg, L.A.; Hart, W.E.; Wilson, D.B.

    1996-01-12

    This work gives a proof of convergence for a randomized learning algorithm that describes how anoles (lizards found in the Carribean) learn a foraging threshold distance. This model assumes that an anole will pursue a prey if and only if it is within this threshold of the anole`s perch. This learning algorithm was proposed by the biologist Roughgarden and his colleagues. They experimentally confirmed that this algorithm quickly converges to the foraging threshold that is predicted by optimal foraging theory our analysis provides an analytic confirmation that the learning algorithm converses to this optimal foraging threshold with high probability.

  3. Individual foraging strategies reveal niche overlap between endangered galapagos pinnipeds.

    PubMed

    Villegas-Amtmann, Stella; Jeglinski, Jana W E; Costa, Daniel P; Robinson, Patrick W; Trillmich, Fritz

    2013-01-01

    Most competition studies between species are conducted from a population-level approach. Few studies have examined inter-specific competition in conjunction with intra-specific competition, with an individual-based approach. To our knowledge, none has been conducted on marine top predators. Sympatric Galapagos fur seals (Arctocephalus galapagoensis) and sea lions (Zalophus wollebaeki) share similar geographic habitats and potentially compete. We studied their foraging niche overlap at Cabo Douglas, Fernandina Island from simultaneously collected dive and movement data to examine spatial and temporal inter- and intra-specific competition. Sea lions exhibited 3 foraging strategies (shallow, intermediate and deep) indicating intra-specific competition. Fur seals exhibited one foraging strategy, diving predominantly at night, between 0-80 m depth and mostly at 19-22 h. Most sea lion dives also occurred at night (63%), between 0-40 m, within fur seals' diving depth range. 34% of sea lions night dives occurred at 19-22 h, when fur seals dived the most, but most of them occurred at dawn and dusk, when fur seals exhibited the least amount of dives. Fur seals and sea lions foraging behavior overlapped at 19 and 21 h between 0-30 m depths. Sea lions from the deep diving strategy exhibited the greatest foraging overlap with fur seals, in time (19 h), depth during overlapping time (21-24 m), and foraging range (37.7%). Fur seals foraging range was larger. Cabo Douglas northwest coastal area, region of highest diving density, is a foraging "hot spot" for both species. Fur seals and sea lions foraging niche overlap occurred, but segregation also occurred; fur seals primarily dived at night, while sea lions exhibited night and day diving. Both species exploited depths and areas exclusive to their species. Niche breadth generally increases with environmental uncertainty and decreased productivity. Potential competition between these species could be greater during warmer periods

  4. New OBS network deployment offshore Ireland

    NASA Astrophysics Data System (ADS)

    Le Pape, Florian; Bean, Chris; Craig, David; Jousset, Philippe; Horan, Clare; Hogg, Colin; Donne, Sarah; McCann, Hannah; Möllhoff, Martin; Kirk, Henning; Ploetz, Aline

    2016-04-01

    With the presence of the stormy NE Atlantic, Ireland is ideally located to investigate further our understanding of ocean generated microseisms and use noise correlation methods to develop seismic imaging in marine environments as well as time-lapse monitoring. In order to study the microseismic activity offshore Ireland, 10 Broad Band Ocean Bottom Seismographs (OBSs) units including hydrophones have been deployed in January 2016 across the shelf offshore Donegal and out into the Rockall Trough. This survey represents the first Broadband passive study in this part of the NE Atlantic. The instruments will be recovered in August 2016 providing 8 months worth of data to study microseisms but also the offshore seismic activity in the area. One of the main goal of the survey is to investigate the spatial and temporal distributions of dominant microseism source regions, close to the microseism sources. Additionally we will study the coupling of seismic and acoustic signals at the sea bed and its evolution in both the deep water and continental shelf areas. Furthermore, the survey also aims to investigate further the relationship between sea state conditions (e.g. wave height, period), seafloor pressure variations and seismic data recorded on both land and seafloor. Finally, the deployed OBS network is also the first ever attempt to closely monitor local offshore earthquakes in Ireland. Ireland seismicity although relatively low can reduce slope stability and poses the possibility of triggering large offshore landslides and local tsunamis.

  5. 33 CFR 165.1156 - Safety Zone; Offshore Marine Terminal, El Segundo, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Safety Zone; Offshore Marine... § 165.1156 Safety Zone; Offshore Marine Terminal, El Segundo, CA. (a) Location. The following area is a... vessels authorized to use the offshore marine terminal for loading or unloading; (ii) Commercial...

  6. 33 CFR 165.1156 - Safety Zone; Offshore Marine Terminal, El Segundo, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Safety Zone; Offshore Marine... § 165.1156 Safety Zone; Offshore Marine Terminal, El Segundo, CA. (a) Location. The following area is a... vessels authorized to use the offshore marine terminal for loading or unloading; (ii) Commercial...

  7. 33 CFR 165.1156 - Safety Zone; Offshore Marine Terminal, El Segundo, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Safety Zone; Offshore Marine... § 165.1156 Safety Zone; Offshore Marine Terminal, El Segundo, CA. (a) Location. The following area is a... vessels authorized to use the offshore marine terminal for loading or unloading; (ii) Commercial...

  8. Feasibility study of wood stork foraging habitat mapping using landsat multispectral data

    SciTech Connect

    Jensen, J.R.; Hodgson, M.E.; Coulter, M.; Mackey, H.E. Jr.

    1986-01-01

    The wood stork is a large wading bird which forages in shallow wetlands up to 70 kilometers from the colony. Landsat data were evaluated to determine if remote sensing data were suitable for locating and estimating the extent of potential foraging habitat for this species over such a large range. Thematic Mapper data of north-central Georgia and the Savannah River floodplain in South Carolina were obtained May 5, 1984. Spectral signatures from known foraging sites near a colony in Georgia were identified. Computer clustering techniques were used to identify and map shallow water and marsh wetland foraging habitats. Foraging acreages were computed, and maps of the locations of candidate foraging sites were produced for a 1520-square-kilometer area. Remote sensing appears to provide a feasible method of evaluating the regional wetland foraging habitat available to this wide-ranging species.

  9. Hydrogeology, water quality, and saltwater intrusion in the Upper Floridan Aquifer in the offshore area near Hilton Head Island, South Carolina, and Tybee Island, Georgia, 1999-2002

    USGS Publications Warehouse

    Falls, W. Fred; Ransom, Camille; Landmeyer, James E.; Reuber, Eric J.; Edwards, Lucy E.

    2005-01-01

    To assess the hydrogeology, water quality, and the potential for saltwater intrusion in the offshore Upper Floridan aquifer, a scientific investigation was conducted near Tybee Island, Georgia, and Hilton Head Island, South Carolina. Four temporary wells were drilled at 7, 8, 10, and 15 miles to the northeast of Tybee Island, and one temporary well was drilled in Calibogue Sound west of Hilton Head Island. The Upper Floridan aquifer at the offshore and Calibogue sites includes the unconsolidated calcareous quartz sand, calcareous quartz sandstone, and sandy limestone of the Oligocene Lazaretto Creek and Tiger Leap Formations, and the limestone of the late Eocene Ocala Limestone and middle Avon Park Formation. At the 7-, 10-, and 15-mile sites, the upper confining unit between the Upper Floridan and surficial aquifers correlates to the Miocene Marks Head Formation. Paleochannel incisions have completely removed the upper confining unit at the Calibogue site and all but a 0.8-foot-thick interval of the confining unit at the 8-mile site, raising concern about the potential for saltwater intrusion through the paleochannel-fill sediments at these two sites. The paleochannel incisions at the Calibogue and 8-mile sites are filled with fine- and coarse-grained sediments, respectively. The hydrogeologic setting and the vertical hydraulic gradients at the 7- and 10-mile sites favored the absence of saltwater intrusion during predevelopment. After decades of onshore water use in Georgia and South Carolina, the 0-foot contour in the regional cone of depression of the Upper Floridan aquifer is estimated to have been at the general location of the 7- and 10-mile sites by the mid-1950s and at or past the 15-mile site by the 1980s. The upward vertical hydraulic gradient reversed, but the presence of more than 17 feet of upper confining unit impeded the downward movement of saltwater from the surficial aquifer to the Upper Floridan aquifer at the 7- and 10-mile sites. At the 10

  10. Getting offshoring right.

    PubMed

    Aron, Ravi; Singh, Jitendra V

    2005-12-01

    The prospect of offshoring and outsourcing business processes has captured the imagination of CEOs everywhere. In the past five years, a rising number of companies in North America and Europe have experimented with this strategy, hoping to reduce costs and gain strategic advantage. But many businesses have had mixed results. According to several studies, half the organizations that have shifted processes offshore have failed to generate the expected financial benefits. What's more, many of them have faced employee resistance and consumer dissatisfaction. Clearly, companies have to rethink how they formulate their offshoring strategies. A three-part methodology can help. First, companies need to prioritize their processes, ranking each based on two criteria: the value it creates for customers and the degree to which the company can capture some of that value. Companies will want to keep their core (highest-priority) processes in-house and consider outsourcing their commodity (low-priority) processes; critical (moderate-priority) processes are up for debate and must be considered carefully. Second, businesses should analyze all the risks that accompany offshoring and look systematically at their critical and commodity processes in terms of operational risk (the risk that processes won't operate smoothly after being offshored) and structural risk (the risk that relationships with service providers may not work as expected). Finally, companies should determine possible locations for their offshore efforts, as well as the organizational forms--such as captive centers and joint ventures--that those efforts might take. They can do so by examining each process's operational and structural risks side by side. This article outlines the tools that will help companies choose the right processes to offshore. It also describes a new organizational structure called the extended organization, in which companies specify the quality of services they want and work alongside providers

  11. Production and transcriptional regulation of proanthocyanidin biosynthesis in forage legumes.

    PubMed

    Zhou, Meiliang; Wei, Li; Sun, Zhanmin; Gao, Lihua; Meng, Yu; Tang, Yixiong; Wu, Yanmin

    2015-05-01

    Proanthocyanidins (PA), also known as condensed tannins, contribute to important forage legumes traits including disease resistance and forage quality. PA in forage plants has both positive and negative effects on feed digestibility and animal performance. The analytical methods and their applicability in measuring the contents of PA in forage plants are essential to studies on their nutritional effects. In spite of important breakthroughs in our understanding of the PA biosynthesis, important questions still remain to be answered such as the PA polymerization and transport. Recent advances in the understanding of transcription factor-mediated gene regulation mechanisms in anthocyanin and PA biosynthetic pathway in model plants suggest new approaches for the metabolic engineering of PA in forage plants. The present review will attempt to present the state-of-the-art of research in these areas and provide an update on the production and metabolic engineering of PA in forage plants. We hope that this will contribute to a better understanding of the ways in which PA production to manipulate the content of PA for beneficial effects in forage plants.

  12. Controls with remote sensing of Common Agricultural Policy (CAP) arable- and forage- area-based subsidies: a yearly more than 700-image and 3-M euro affair

    NASA Astrophysics Data System (ADS)

    Astrand, Par-Johan; Wirnhardt, Csaba; Biagini, Bruno; Weber, Michaela; Hellerman, Rani

    2004-11-01

    Since 1993, the EC DG Agriculture has promoted the use of "Controls with Remote Sensing" (CwRS) as appropriate control system within the Common Agricultural Policy (CAP). CwRS is considered suitable to check if agricultural area-based subsidies (yearly > 25 billion euro EC expenditure) are correctly granted. On the basis of the Council Regulation (EC) 165/94 and of the Commission Regulation (EC) 601/94, the Commission Services are required to centralize the satellite images acquisition. This task has been managed by the MARS Project at the JRC since 1999, where the whole controls activity is coordinated. The activity also includes the setting up of specifications, recommendations, performing Quality Controls (QC) and auditing of the selected contractors, and evaluation of new methods. Satellite image acquisition involves the control site definition within each Member State, and the subsequent chain of image acquisition over the defined sites including feasibility with image providers, acquisition, validation, ordering, delivery and final archiving of the imagery. In summary the 2004 years campaign involved a budget of approximately 3.2 M euro to cover some 150 High Resolution (HR) sites and 71 Very High Resolution (VHR) sites. The objective of this paper is to describe the CwRS image acquisition with emphasis on the Ikonos, Quickbird, and EROS A satellites for the 2004 years CwRS Campaign, to give preliminary results, recommendations and future trends.

  13. The Role of Non-Foraging Nests in Polydomous Wood Ant Colonies.

    PubMed

    Ellis, Samuel; Robinson, Elva J H

    2015-01-01

    A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non-foraging nests and the rest of the colony; (iii) measured the amount of extra-nest activity around non-foraging and foraging nests. We used these datasets to investigate the extent to which non-foraging nests within polydomous colonies are acting as: part of the colony expansion process; hunting and scavenging specialists; brood-development specialists; seasonal foragers; or a selfish strategy exploiting the foraging effort of the rest of the colony. We found that, rather than having a specialised role, non-foraging nests are part of the process of colony expansion. Polydomous colonies expand by founding new nests in the area surrounding the existing nests. Nests founded near food begin foraging and become part of the colony; other nests are not founded near food sources and do not initially forage. Some of these non-foraging nests eventually begin foraging; others do not and are abandoned. This is a method of colony growth not available to colonies inhabiting a single nest, and may be an important advantage of the polydomous nesting strategy, allowing the colony to expand into profitable areas.

  14. Task 1: Whole-body concentrations of elements in kelp bass (Paralabrax clathratus), kelp rockfish (Sebastes atrovirens), and Pacific sanddab (Citharichthys sordidus) from offshore oil platforms and natural areas in the Southern California Bight

    USGS Publications Warehouse

    Love, Milton S.

    2009-01-01

    Resource managers are concerned that offshore oil platforms in the Southern California Bight may be contributing to environmental contaminants accumulated by marine fishes. To examine this possibility, 18 kelp bass (Paralabrax clathratus), 80 kelp rockfish (Sebastes atrovirens), and 98 Pacific sanddab (Citharichthys sordidus) were collected from five offshore oil platforms and 10 natural areas during 2005-2006 for whole-body analysis of 63 elements. The natural areas, which served as reference sites, were assumed to be relatively uninfluenced by contaminants originating from platforms. Forty-two elements were excluded from statistical comparisons for one of three reasons: they consisted of major cations that were unlikely to accumulate to potentially toxic concentrations under ambient exposure conditions; they were not detected by the analytical procedures; or they were detected at concentrations too low to yield reliable quantitative measurements. The remaining 21 elements consisted of aluminum, arsenic, barium, cadmium, chromium, cobalt, copper, gallium, iron, lead, lithium, manganese, mercury, nickel, rubidium, selenium, strontium, tin, titanium, vanadium, and zinc. Statistical comparisons of these 21 elements indicated that none consistently exhibited higher concentrations at oil platforms than at natural areas. Eight comparisons yielded significant interaction effects between total length (TL) of the fish and the two habitat types (oil platforms and natural areas). This indicated that relations between certain elemental concentrations (i.e., copper, rubidium, selenium, tin, titanium, and vanadium) and habitat type varied by TL of affected fish species. To better understand these interactions, we examined elemental concentrations in very small and very large individuals of affected species. Although significant interactions were detected for rubidium, tin, and selenium in kelp rockfish, the concentrations of these elements did not differ significantly between

  15. H.R. 73: A Bill to protect the ecologically fragile coastal resources of south Florida by prohibiting offshore oil and gas activities and by cancelling Federal leases in the area of the Outer Continental Shelf adjacent to the south Florida coast. Introduced in the House of Representatives, One Hundred Fourth Congress, First session

    SciTech Connect

    1995-12-31

    This document contains H.R. 73, A Bill to protect the ecologically fragile coastal resources of south Florida by prohibiting offshore oil and gas activities and by cancelling Federal leases in the area of the Outer Continental Shelf adjacent to south Florida. This Bill was introduced in the House of Representatives, 104th Congress, First Session, January 4, 1995.

  16. Cut drydocking costs for offshore rigs

    SciTech Connect

    Albaugh, E.K.

    1985-07-01

    Heavy-lift transport vessels (HLVs) can provide an economic alternative to the conventional shipyard approach of drydocking mobile offshore rigs for regulatory body inspections and/or repairs. Contractors now can drydock rigs in areas of the world where conventional drydocks are unavailable. This article discusses pros and cons of conventional shipyard drydocking and the HLV approach.

  17. Solar power satellite offshore rectenna study

    NASA Astrophysics Data System (ADS)

    1980-05-01

    Offshore rectennas are feasible and cost competitive with land rectennas but the type of rectenna suitable for offshore use is quite different from that specified in the present reference system. A nonground plane design minimizes the weight and greatly reduces the number of costly support towers. This perferred design is an antenna array consisting of individually encapsulated dipoles with reflectors or tagis supported on feed wires. Such a 5 GW rectenna could be built at a 50 m water depth site to withstand hurricane, winter storm, and icing conditions for a one time cost of $5.7 billion. Subsequent units would be about 1.3 less expensive. More benign and more shallow water sites would result in substantially lower costs. The major advantage of an offshore rectenna is the removal of microwave radiation from populated areas.

  18. Solar power satellite offshore rectenna study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Offshore rectennas are feasible and cost competitive with land rectennas but the type of rectenna suitable for offshore use is quite different from that specified in the present reference system. A nonground plane design minimizes the weight and greatly reduces the number of costly support towers. This perferred design is an antenna array consisting of individually encapsulated dipoles with reflectors or tagis supported on feed wires. Such a 5 GW rectenna could be built at a 50 m water depth site to withstand hurricane, winter storm, and icing conditions for a one time cost of $5.7 billion. Subsequent units would be about 1.3 less expensive. More benign and more shallow water sites would result in substantially lower costs. The major advantage of an offshore rectenna is the removal of microwave radiation from populated areas.

  19. Energy from Offshore Wind: Preprint

    SciTech Connect

    Musial, W.; Butterfield, S.; Ram, B.

    2006-02-01

    This paper provides an overview of the nascent offshore wind energy industry including a status of the commercial offshore industry and the technologies that will be needed for full market development.

  20. Offshore rectenna feasbility

    NASA Technical Reports Server (NTRS)

    Freeman, J. W.; Hervey, D.; Glaser, P.

    1980-01-01

    A preliminary study of the feasibility and cost of an offshore rectenna to serve the upper metropolitan east coast was performed. A candidate site at which to build a 5 GW rectenna was selected on the basis of proximity to load centers, avoidance of shipping lanes, sea floor terrain, and relocated conditions. Several types of support structures were selected for study based initially on the reference system rectenna concept of a wire mesh ground screen and dipoles each with its own rectifier and filter circuits. Possible secondary uses of an offshore rectenna were examined and are evaluated.

  1. Evidence for ship noise impacts on humpback whale foraging behaviour.

    PubMed

    Blair, Hannah B; Merchant, Nathan D; Friedlaender, Ari S; Wiley, David N; Parks, Susan E

    2016-08-01

    Noise from shipping activity in North Atlantic coastal waters has been steadily increasing and is an area of growing conservation concern, as it has the potential to disrupt the behaviour of marine organisms. This study examines the impacts of ship noise on bottom foraging humpback whales (Megaptera novaeangliae) in the western North Atlantic. Data were collected from 10 foraging whales using non-invasive archival tags that simultaneously recorded underwater movements and the acoustic environment at the whale. Using mixed models, we assess the effects of ship noise on seven parameters of their feeding behaviours. Independent variables included the presence or absence of ship noise and the received level of ship noise at the whale. We found significant effects on foraging, including slower descent rates and fewer side-roll feeding events per dive with increasing ship noise. During 5 of 18 ship passages, dives without side-rolls were observed. These findings indicate that humpback whales on Stellwagen Bank, an area with chronically elevated levels of shipping traffic, significantly change foraging activity when exposed to high levels of ship noise. This measureable reduction in within-dive foraging effort of individual whales could potentially lead to population-level impacts of shipping noise on baleen whale foraging success.

  2. Do naive juvenile seabirds forage differently from adults?

    PubMed

    Riotte-Lambert, Louise; Weimerskirch, Henri

    2013-10-07

    Foraging skills of young individuals are assumed to be inferior to those of adults. The reduced efficiency of naive individuals may be the primary cause of the high juvenile mortality and explain the deferment of maturity in long-lived species. However, the study of juvenile and immature foraging behaviour has been limited so far. We used satellite telemetry to compare the foraging movements of juveniles, immatures and breeding adult wandering albatrosses Diomedea exulans, a species where foraging success is positively influenced by the distance covered daily. We showed that juveniles are able to use favourable winds as soon as the first month of independence, but cover shorter distances daily and spend more time sitting on water than adults during the first two months after fledging. These reduced movement capacities do not seem to be the cause of higher juvenile mortality. Moreover, juveniles almost never restrict their movement to specific areas, as adults and immatures frequently do over shelf edges or oceanic zones, which suggest that the location of appropriate areas is learned through experience. Immatures and adults have equivalent movement capacities, but when they are central place foragers, i.e. when adults breed or immatures come to the colony to display and pair, immatures make shorter trips than adults. The long duration of immaturity in this species seems to be related to a long period of learning to integrate the foraging constraints associated with reproduction and central place foraging. Our results indicate that foraging behaviour of young albatrosses is partly innate and partly learned progressively over immaturity. The first months of learning appear critical in terms of survival, whereas the long period of immaturity is necessary for young birds to attain the skills necessary for efficient breeding without fitness costs.

  3. Do naive juvenile seabirds forage differently from adults?

    PubMed Central

    Riotte-Lambert, Louise; Weimerskirch, Henri

    2013-01-01

    Foraging skills of young individuals are assumed to be inferior to those of adults. The reduced efficiency of naive individuals may be the primary cause of the high juvenile mortality and explain the deferment of maturity in long-lived species. However, the study of juvenile and immature foraging behaviour has been limited so far. We used satellite telemetry to compare the foraging movements of juveniles, immatures and breeding adult wandering albatrosses Diomedea exulans, a species where foraging success is positively influenced by the distance covered daily. We showed that juveniles are able to use favourable winds as soon as the first month of independence, but cover shorter distances daily and spend more time sitting on water than adults during the first two months after fledging. These reduced movement capacities do not seem to be the cause of higher juvenile mortality. Moreover, juveniles almost never restrict their movement to specific areas, as adults and immatures frequently do over shelf edges or oceanic zones, which suggest that the location of appropriate areas is learned through experience. Immatures and adults have equivalent movement capacities, but when they are central place foragers, i.e. when adults breed or immatures come to the colony to display and pair, immatures make shorter trips than adults. The long duration of immaturity in this species seems to be related to a long period of learning to integrate the foraging constraints associated with reproduction and central place foraging. Our results indicate that foraging behaviour of young albatrosses is partly innate and partly learned progressively over immaturity. The first months of learning appear critical in terms of survival, whereas the long period of immaturity is necessary for young birds to attain the skills necessary for efficient breeding without fitness costs. PMID:23926153

  4. Root Nutrient Foraging1

    PubMed Central

    Giehl, Ricardo F.H.; von Wirén, Nicolaus

    2014-01-01

    During a plant's lifecycle, the availability of nutrients in the soil is mostly heterogeneous in space and time. Plants are able to adapt to nutrient shortage or localized nutrient availability by altering their root system architecture to efficiently explore soil zones containing the limited nutrient. It has been shown that the deficiency of different nutrients induces root architectural and morphological changes that are, at least to some extent, nutrient specific. Here, we highlight what is known about the importance of individual root system components for nutrient acquisition and how developmental and physiological responses can be coupled to increase nutrient foraging by roots. In addition, we review prominent molecular mechanisms involved in altering the root system in response to local nutrient availability or to the plant's nutritional status. PMID:25082891

  5. Root nutrient foraging.

    PubMed

    Giehl, Ricardo F H; von Wirén, Nicolaus

    2014-10-01

    During a plant's lifecycle, the availability of nutrients in the soil is mostly heterogeneous in space and time. Plants are able to adapt to nutrient shortage or localized nutrient availability by altering their root system architecture to efficiently explore soil zones containing the limited nutrient. It has been shown that the deficiency of different nutrients induces root architectural and morphological changes that are, at least to some extent, nutrient specific. Here, we highlight what is known about the importance of individual root system components for nutrient acquisition and how developmental and physiological responses can be coupled to increase nutrient foraging by roots. In addition, we review prominent molecular mechanisms involved in altering the root system in response to local nutrient availability or to the plant's nutritional status.

  6. Whole-body concentrations of elements in three fish species from offshore oil platforms and natural areas in the Southern California Bight, USA

    USGS Publications Warehouse

    Love, Milton S.; Saiki, Michael K.; May, Thomas W.; Yee, Julie L.

    2013-01-01

    elements. Forty-two elements were excluded from statistical comparisons as they (1) consisted of major cations that were unlikely to accumulate to potentially toxic concentrations; (2) were not detected by the analytical procedures; or (3) were detected at concentrations too low to yield reliable quantitative measurements. The remaining 21 elements consisted of aluminum, arsenic, barium, cadmium, chromium, cobalt, copper, gallium, iron, lead, lithium, manganese, mercury, nickel, rubidium, selenium, strontium, tin, titanium, vanadium, and zinc. Statistical comparisons of these elements indicated that none consistently exhibited higher concentrations at oil platforms than at natural areas. However, the concentrations of copper, selenium, titanium, and vanadium in Pacific sanddab were unusual because small individuals exhibited either no differences between oil platforms and natural areas or significantly lower concentrations at oil platforms than at natural areas, whereas large individuals exhibited significantly higher concentrations at oil platforms than at natural areas.

  7. 46 CFR 131.320 - Safety orientation for offshore workers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... informing each offshore worker of— (1) In general terms, emergency and evacuation procedures; (2) Locations of emergency exits and of embarkation areas for survival craft; (3) Locations of stowage...

  8. Offshore platform cathodic protection retrofits

    SciTech Connect

    Turnipseed, S.P.

    1996-10-01

    Cathodic protection (CP) is the primary technique used for underwater corrosion control on the majority of offshore steel structures. Offshore platforms are often kept in service far beyond their original design life. Refurbishment of the CP system is required when adequate protection can no longer be maintained. Various offshore platform CP retrofit designs are discussed.

  9. R & D on Offshore Wind Power Generation System in Japan

    NASA Astrophysics Data System (ADS)

    Oishi, Kazuhito; Fukumoto, Yukinari

    Offshore wind energy has been widely exploited in Europe. Having a long coastline, the offshore wind energy will be the one of the important solutions for the increase of renewable energy in Japan. However, due to the difference in wind and marine condition between Japan and Europe, the safety, the environmental impact and the economical feasibility of the offshore wind power generation system have to be investigated in Japan. According to the data observed offshore, the wind speed is enough higher than that on land and the wind energy is economically feasible. In order to utilize the energy, the design method of the foundation against very high waves in typhoon storm should be established. For shallow offshore coastal area, gravity foundation type has been improved by hydraulic experiment. Additionally, for deeper ocean, floating types such as semi-submersible float and spar-buoy have been researched.

  10. Offshore Wind Energy Systems

    ERIC Educational Resources Information Center

    Musgrove, P.

    1978-01-01

    Explores the possibility of installing offshore windmills to provide electricity and to save fuel for the United Kingdom. Favors their deployment in clusters to facilitate supervision and minimize cost. Discusses the power output and the cost involved and urges their quick development. (GA)

  11. Department of Defense Offshore Military Activities Program

    DTIC Science & Technology

    1987-03-16

    joint use of offshore areas for military and mineral exploration or developmental purposes. (See enclosure 2.) In carrying out negotiations with elements...that from time to time and from place to place the requirements for mineral exploration /development and defense related activities may conflict. In...area, certain defense- related activities on the OCS may be irreconcilable with mineral exploration / development and will, under the procedures

  12. Root foraging influences plant growth responses to earthworm foraging.

    PubMed

    Cameron, Erin K; Cahill, James F; Bayne, Erin M

    2014-01-01

    Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants.

  13. Sex-specific foraging behaviour in a monomorphic seabird.

    PubMed Central

    Lewis, S; Benvenuti, S; Dall'Antonia, L; Griffiths, R; Money, L; Sherratt, T N; Wanless, S; Hamer, K C

    2002-01-01

    Sexual differences in the foraging behaviour of parents have been observed in a number of sexually sizedimorphic birds, particularly seabirds, and the usual inference has been that these sex-specific differences are mediated primarily by differences in body size. To test this explanation, we compared the foraging behaviour of parents in a monomorphic seabird species, the northern gannet Morus bassanus. Using specially designed instruments and radio telemetry we found that individuals of both sexes were consistent in the directions and durations of their foraging trips. However, there were significant differences in the foraging behaviour of males and females. Female gannets were not only more selective than males in the areas where they foraged, but they also made longer, deeper dives and spent more time on the sea surface than males. As the sexes are morphologically similar in this species, then these differences are unlikely to have been mediated by body size. Our work highlights the need to investigate sexual differences in the foraging behaviour of seabirds and other species more closely, in order to test alternative theories that do not rely on differences in body size. PMID:12204129

  14. Cotton Rats Alter Foraging in Response to an Invasive Ant

    PubMed Central

    Darracq, Andrea K.; Conner, L. Mike; Brown, Joel S.; McCleery, Robert A.

    2016-01-01

    We assessed the effects of red imported fire ants (Solenopsis invicta; hereafter fire ant) on the foraging of hispid cotton rats (Sigmodon hispidus). We used a manipulative experiment, placing resource patches with a known amount of millet seed within areas with reduced (RIFA [–]) or ambient (RIFA [+]) numbers of fire ants. We measured giving up densities (the amount of food left within each patch) within the resource patches for 4 days to quantify the effects of fire ants on cotton rat foraging. We assessed the effects of fire ant treatment (RIFA), Day, and their interaction on cotton rat giving up densities. Giving up densities on RIFA [+] grids were nearly 2.2 times greater across all foraging days and ranged from 1.6 to 2.3 times greater from day 1 to day 4 than the RIFA [–] grids. From day 1 to day 4, mean giving up densities decreased significantly faster for the RIFA [–] than RIFA [+] treatments, 58% and 13%, respectively. Our results demonstrate that cotton rats perceive a risk of injury from fire ants, which is likely caused by interference competition, rather than direct predation. Envenomation from ants likely decrease the foraging efficiency of cotton rats resulting in more time spent foraging. Increased time spent foraging is likely stressful in terms of the opportunity for direct injury and encounters with other predators. These indirect effects may reduce an individual cotton rat’s fitness and translate into lowered population abundances. PMID:27655320

  15. Foraging decisions, patch use, and seasonality in egrets (Aves: ciconiiformes)

    USGS Publications Warehouse

    Erwin, R.M.

    1985-01-01

    Feeding snowy (Egretta thula) and great (Casmerodius albus) egrets were observed during 2 breeding seasons in coastal New Jersey and 2 brief winter periods in northeast Florida (USA). A number of tests based on assumptions of foraging models, predictions from foraging theory, and earlier empirical tests concerning time allocation and movement in foraging patches was made. Few of the expectations based on foraging theory and/or assumptions were supported by the empirical evidence. Snowy egrets fed with greater intensity and efficiency during the breeding season (when young were being fed) than during winter. They also showed some tendency to leave patches when their capture rate declined, and they spent more time foraging in patches when other birds were present nearby. Great egrets showed few of these tendencies, although they did leave patches when their intercapture intervals increased. Satiation differences had some influence on feeding rates in snowy egrets, but only at the end of feeding bouts. Some individuals of both species revisited areas in patches that had recently been exploited, and success rates were usually higher after the 2nd visit. Apparently, for predators of active prey, short-term changes in resource availability ('resource depression') may be more important than resource depletion, a common assumption in most optimal foraging theory models.

  16. Environmental variability drives shifts in the foraging behaviour and reproductive success of an inshore seabird.

    PubMed

    Kowalczyk, Nicole D; Reina, Richard D; Preston, Tiana J; Chiaradia, André

    2015-08-01

    Marine animals forage in areas that aggregate prey to maximize their energy intake. However, these foraging 'hot spots' experience environmental variability, which can substantially alter prey availability. To survive and reproduce animals need to modify their foraging in response to these prey shifts. By monitoring their inter-annual foraging behaviours, we can understand which environmental variables affect their foraging efficiency, and can assess how they respond to environmental variability. Here, we monitored the foraging behaviour and isotopic niche of little penguins (Eudyptula minor), over 3 years (2008, 2011, and 2012) of climatic and prey variability within Port Phillip Bay, Australia. During drought (2008), penguins foraged in close proximity to the Yarra River outlet on a predominantly anchovy-based diet. In periods of heavy rainfall, when water depth in the largest tributary into the bay (Yarra River) was high, the total distance travelled, maximum distance travelled, distance to core-range, and size of core- and home-ranges of penguins increased significantly. This larger foraging range was associated with broad dietary diversity and high reproductive success. These results suggest the increased foraging range and dietary diversity of penguins were a means to maximize resource acquisition rather than a strategy to overcome local depletions in prey. Our results demonstrate the significance of the Yarra River in structuring predator-prey interactions in this enclosed bay, as well as the flexible foraging strategies of penguins in response to environmental variability. This plasticity is central to the survival of this small-ranging, resident seabird species.

  17. Mapping Seabird Sensitivity to Offshore Wind Farms

    PubMed Central

    Bradbury, Gareth; Trinder, Mark; Furness, Bob; Banks, Alex N.; Caldow, Richard W. G.; Hume, Duncan

    2014-01-01

    We present a Geographic Information System (GIS) tool, SeaMaST (Seabird Mapping and Sensitivity Tool), to provide evidence on the use of sea areas by seabirds and inshore waterbirds in English territorial waters, mapping their relative sensitivity to offshore wind farms. SeaMaST is a freely available evidence source for use by all connected to the offshore wind industry and will assist statutory agencies in assessing potential risks to seabird populations from planned developments. Data were compiled from offshore boat and aerial observer surveys spanning the period 1979–2012. The data were analysed using distance analysis and Density Surface Modelling to produce predicted bird densities across a grid covering English territorial waters at a resolution of 3 km×3 km. Coefficients of Variation were estimated for each grid cell density, as an indication of confidence in predictions. Offshore wind farm sensitivity scores were compiled for seabird species using English territorial waters. The comparative risks to each species of collision with turbines and displacement from operational turbines were reviewed and scored separately, and the scores were multiplied by the bird density estimates to produce relative sensitivity maps. The sensitivity maps reflected well the amassed distributions of the most sensitive species. SeaMaST is an important new tool for assessing potential impacts on seabird populations from offshore development at a time when multiple large areas of development are proposed which overlap with many seabird species’ ranges. It will inform marine spatial planning as well as identifying priority areas of sea usage by marine birds. Example SeaMaST outputs are presented. PMID:25210739

  18. Mapping seabird sensitivity to offshore wind farms.

    PubMed

    Bradbury, Gareth; Trinder, Mark; Furness, Bob; Banks, Alex N; Caldow, Richard W G; Hume, Duncan

    2014-01-01

    We present a Geographic Information System (GIS) tool, SeaMaST (Seabird Mapping and Sensitivity Tool), to provide evidence on the use of sea areas by seabirds and inshore waterbirds in English territorial waters, mapping their relative sensitivity to offshore wind farms. SeaMaST is a freely available evidence source for use by all connected to the offshore wind industry and will assist statutory agencies in assessing potential risks to seabird populations from planned developments. Data were compiled from offshore boat and aerial observer surveys spanning the period 1979-2012. The data were analysed using distance analysis and Density Surface Modelling to produce predicted bird densities across a grid covering English territorial waters at a resolution of 3 km×3 km. Coefficients of Variation were estimated for each grid cell density, as an indication of confidence in predictions. Offshore wind farm sensitivity scores were compiled for seabird species using English territorial waters. The comparative risks to each species of collision with turbines and displacement from operational turbines were reviewed and scored separately, and the scores were multiplied by the bird density estimates to produce relative sensitivity maps. The sensitivity maps reflected well the amassed distributions of the most sensitive species. SeaMaST is an important new tool for assessing potential impacts on seabird populations from offshore development at a time when multiple large areas of development are proposed which overlap with many seabird species' ranges. It will inform marine spatial planning as well as identifying priority areas of sea usage by marine birds. Example SeaMaST outputs are presented.

  19. Nocturnal activity and foraging of prairie raccoons (Procyon lotor) in North Dakota

    USGS Publications Warehouse

    Greenwood, R.J.

    1982-01-01

    Nocturnal activity and foraging of 39 radio-equipped raccoons (Procyon lotor) in eastern North Dakota were studied from April-July in 1974-1976. Sixteen of the raccoons were collected after foraging bouts for stomach content analysis. Raccoon activity consisted of running (13%), walking (49%) and local movement in confined areas (38%). Local movement was foraging on large or locally abundant food items. Adult males traveled farther in a night, ran twice as often, and moved locally only half as often as adult females and yearlings. Differences in activity patterns between adult females and yearlings were not detected. There was no difference among age-sex groups in use of foraging habitats. All raccoons foraged extensively in farmyards and wetlands. Stomach content analysis substantiated foraging determinations obtained by radiotelemetry. Principal foods were grain, aquatic animals, rodents, birds and bird eggs.

  20. Remote sensing of endangered species foraging habitats: a wood stork example

    SciTech Connect

    Jensen, J.R.; Hodgson, M.E.; Mackey, H.E. Jr.; Coulter, M.

    1986-03-01

    Potential foraging sites for an endangered species, the wood stork, were identified using thematic mapper data for May 1984, for a section of north-central Georgia. This was accomplished using innovative clustering techniques applied to known wood stork foraging sites around the Birdsville Colony in Georgia. The signatures for known sites were then geographically extended to a 1,520-square-kilometer region surrounding the Birdsville Colony. Thematic maps were produced, and foraging area acreages computed providing a regional assessment of existing and potential wood stork foraging sits. 16 refs., 6 figs.

  1. Evidence for foraging -site fidelity and individual foraging behavior of pelagic cormorants rearing chicks in the gulf of Alaska

    USGS Publications Warehouse

    Kotzerka, J.; Hatch, Shyla A.; Garthe, S.

    2011-01-01

    The Pelagic Cormorant (Phalacrocorax pelagicus) is the most widespread cormorant in the North Pacific, but little is known about its foraging and diving behavior. However, knowledge of seabirds' foraging behavior is important to understanding their function in the marine environment. In 2006, using GPS dataloggers, we studied the foraging behavior of 14 male Pelagic Cormorants rearing chicks on Middleton Island, Alaska. For foraging, the birds had high fidelity to a small area 8 km north of the colony. Within that area, the cormorants' diving activity was of two distinct kinds-near-surface dives (1-6 m) and benthic dives (28-33 m). Individuals were consistent in the depths of their dives, either mostly shallow or mostly deep. Few showed no depth preference. Dive duration, time at maximum depth, and pauses at the water surface between consecutive dives were shorter for shallow dives than for deep dives. The cormorants made dives of both types throughout the day, but the frequency of deep dives increased toward evening. Maximum foraging range was 9 km; maximum total distance traveled per trip was 43.4 km. Trip durations ranged from 0.3 to 7.7 hr. Maximum depth of a dive was 42.2 m, and duration of dives ranged from 4 to 120 sec. We found that Pelagic Cormorants at Middleton Island were faithful to one particular foraging area and individuals dived in distinct patterns. Distinct, specialized foraging behavior may be advantageous in reducing intra- and interspecific competition but may also render the species vulnerable to changing environmental conditions. Copyright ?? The Cooper Ornithological Society 2011.

  2. Quantifying the hurricane catastrophe risk to offshore wind power.

    PubMed

    Rose, Stephen; Jaramillo, Paulina; Small, Mitchell J; Apt, Jay

    2013-12-01

    The U.S. Department of Energy has estimated that over 50 GW of offshore wind power will be required for the United States to generate 20% of its electricity from wind. Developers are actively planning offshore wind farms along the U.S. Atlantic and Gulf coasts and several leases have been signed for offshore sites. These planned projects are in areas that are sometimes struck by hurricanes. We present a method to estimate the catastrophe risk to offshore wind power using simulated hurricanes. Using this method, we estimate the fraction of offshore wind power simultaneously offline and the cumulative damage in a region. In Texas, the most vulnerable region we studied, 10% of offshore wind power could be offline simultaneously because of hurricane damage with a 100-year return period and 6% could be destroyed in any 10-year period. We also estimate the risks to single wind farms in four representative locations; we find the risks are significant but lower than those estimated in previously published results. Much of the hurricane risk to offshore wind turbines can be mitigated by designing turbines for higher maximum wind speeds, ensuring that turbine nacelles can turn quickly to track the wind direction even when grid power is lost, and building in areas with lower risk.

  3. United States Offshore Wind Resource Assessment

    NASA Astrophysics Data System (ADS)

    Schwartz, M.; Haymes, S.; Heimiller, D.

    2008-12-01

    The utilization of the offshore wind resource will be necessary if the United States is to meet the goal of having 20% of its electricity generated by wind power because many of the electrical load centers in the country are located along the coastlines. The United States Department of Energy, through its National Renewable Energy Laboratory (NREL), has supported an ongoing project to assess the wind resource for the offshore regions of the contiguous United States including the Great Lakes. Final offshore maps with a horizontal resolution of 200 meters (m) have been completed for Texas, Louisiana, Georgia, northern New England, and the Great Lakes. The ocean wind resource maps extend from the coastline to 50 nautical miles (nm) offshore. The Great Lake maps show the resource for all of the individual lakes. These maps depict the wind resource at 50 m above the water as classes of wind power density. Class 1 represents the lowest available wind resource, while Class 7 is the highest resource. Areas with Class 5 and higher wind resource can be economical for offshore project development. As offshore wind turbine technology improves, areas with Class 4 and higher resource should become economically viable. The wind resource maps are generated using output from a modified numerical weather prediction model combined with a wind flow model. The preliminary modeling is performed by AWS Truewind under subcontract to NREL. The preliminary model estimates are sent to NREL to be validated. NREL validates the preliminary estimates by comparing 50 m model data to available measurements that are extrapolated to 50 m. The validation results are used to modify the preliminary map and produce the final resource map. The sources of offshore wind measurement data include buoys, automated stations, lighthouses, and satellite- derived ocean wind speed data. The wind electric potential is represented as Megawatts (MW) of potential installed capacity and is based on the square

  4. Performance and economic analyses of year-round forage systems for forage-fed beef production in the Gulf Coast.

    PubMed

    Scaglia, G; Rodriguez, J; Gillespie, J; Bhandari, B; Wang, J J; McMillin, K W

    2014-12-01

    On a global scale, most beef is produced from grazing pastures or rangelands. Certain limitations exist, however, such as not having adequate animal rates of gain for marbling and availability of adequate forage nutritional value and quantity for constant animal weight gains. In the last 20 yr, there has been an increased interest in forage-fed beef for multiple reasons (health related, environmental concerns, and welfare issues). Starting on June 5, 13, 14, and 8 in 4 consecutive yr, 54 steers (initial BW=259±5.6 kg; average of 9 mo of age) were randomly allotted to 3 yr-round forage systems. Each system occupied 6 ha/replicate and had the same stocking rate. System 1 had annual ryegrass (Lolium multiflorum) for winter grazing and bermudagrass (Cynodon dactylon) for summer grazing; while Systems 2 and 3 added rye and a clover mix to the ryegrass and diversified the use of pastures in the fall (dallisgrass [Paspalum dilatatum] and clovers [Trifolium spp.]). System 3 added the use of annual summer forages. During their respective growing season for each forage or forage mix, mass and height did not limit animal performance; however, there was a sampling date effect (P<0.05) for nutritive value variables since it decreased as forages became mature. The ADG observed (0.44 kg) for all systems (P=0.78) during summer was lower than expected and might have been limited by the observed temperature as well as forage nutritive value. Systems 1 and 2 had more grazing days (P=0.03) during summer (155 and 146 d, respectively) compared to System 3 (132 d) due to the greater pasture area of bermudagrass in those systems. Steers in System 3 were fed more hay for a longer period of time (P<0.05) than on the other 2 systems. System 1 and 2 produced more hay per hectare than System 3 (P<0.05). No differences (P>0.05) were detected between systems in ADG year round, during the winter season, or carcass characteristics. Return over total direct costs and total specified expenses were

  5. Root Foraging Performance and Life-History Traits.

    PubMed

    Weiser, Martin; Koubek, Tomáš; Herben, Tomáš

    2016-01-01

    Plants use their roots to forage for nutrients in heterogeneous soil environments, but different plant species vastly differ in the intensity of foraging they perform. This diversity suggests the existence of constraints on foraging at the species level. We therefore examined the relationships between the intensity of root foraging and plant body traits across species in order to estimate the degree of coordination between plant body traits and root foraging as a form of plant behavior. We cultivated 37 perennial herbaceous Central European species from open terrestrial habitats in pots with three different spatial gradients of nutrient availability (steep, shallow, and no gradient). We assessed the intensity of foraging as differences in root placement inside pots with and without a spatial gradient of resource supply. For the same set of species, we retrieved data about body traits from available databases: maximum height at maturity, mean area of leaf, specific leaf area, shoot lifespan, ability to self-propagate clonally, maximal lateral spread (in clonal plants only), realized vegetative growth in cultivation, and realized seed regeneration in cultivation. Clonal plants and plants with extensive vegetative growth showed considerably weaker foraging than their non-clonal or slow-growing counterparts. There was no phylogenetic signal in the amount of expressed root foraging intensity. Since clonal plants foraged less than non-clonals and foraging intensity did not seem to be correlated with species phylogeny, we hypothesize that clonal growth itself (i.e., the ability to develop at least partly self-sustaining ramets) may be an answer to soil heterogeneity. Whereas unitary plants use roots as organs specialized for both resource acquisition and transport to overcome spatial heterogeneity in resource supply, clonal plants separate these two functions. Becoming a clonal plant allows higher specialization at the organ level, since a typical clonal plant can be

  6. 26th annual offshore technology conference, 1994 proceedings

    SciTech Connect

    Not Available

    1994-01-01

    This conference is the world's largest and most comprehensive technical conference and exhibition on offshore resource development. The four Proceedings volumes have been separated by major areas of interest, with relative sessions included in each volume. This Volume 3 contains information relative to offshore platforms and marine system designs. It describes both the installation and decommissioning of offshore platforms, retrofitting platforms to meet current safety standards, and technology assessments for both drilling and platform designs. Papers are also provided which describe maintenance and repair technologies for damages to platform.

  7. California State Waters Map Series: offshore of San Francisco, California

    USGS Publications Warehouse

    Cochrane, Guy R.; Johnson, Samuel Y.; Dartnell, Peter; Greene, H. Gary; Erdey, Mercedes D.; Golden, Nadine E.; Hartwell, Stephen R.; Endris, Charles A.; Manson, Michael W.; Sliter, Ray W.; Kvitek, Rikk G.; Watt, Janet Tilden; Ross, Stephanie L.; Bruns, Terry R.; Cochrane, Guy R.; Cochran, Susan A.

    2015-01-01

    Circulation over the continental shelf in the Offshore of San Francisco map area is dominated by the southward-flowing California Current, an eastern limb of the North Pacific Gyre that flows from Oregon to Baja California. At its midpoint offshore of central California, the California Current transports subarctic surface waters southeastward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. Ocean temperatures offshore of central California have increased over the past 50 years, driving an ecosystem shift from the productive subarctic regime towards a depopulated subtropical environment.

  8. Arctic offshore platform

    SciTech Connect

    Bhula, D.N.

    1984-01-24

    An offshore structure is disclosed for use in drilling and producing wells in arctic regions having a conical shaped lower portion that extends above the surface of the water and a cylindrical upper section. The conical portion is provided with a controlled stiffness outer surface for withstanding the loads produced by ice striking the structure. The stiffness properties of the outer shell and flexible members are designed to distribute the load and avoid high local loads on the inner parts of the structure.

  9. Wind Energy: Offshore Permitting

    DTIC Science & Technology

    2008-05-01

    Technological advancements and tax incentives have driven a global expansion in the development of renewable energy resources. Wind energy , in...particular, is now often cited as the fastest growing commercial energy source in the world. Currently, all U.S. wind energy facilities are based on land...authority to permit and regulate offshore wind energy development within the zones of the oceans under its jurisdiction. The federal government and coastal

  10. Atmospheric methane emissions coupled to a CO2-sink at an Arctic shelf seep area offshore NW Svalbard: Introducing the "Seep-Fertilization Hypothesis"

    NASA Astrophysics Data System (ADS)

    Greinert, Jens; Pohlman, John; Silyakova, Anna; Mienert, Jürgen; Ruppel, Carolyn; Casso, Michael

    2015-04-01

    Documented warming of intermediate waters by ~1C over the past 30 years along the western Svalbard margin has been suggested as a driver of climate-change induced dissociation of marine methane hydrate. However, recent evidence suggests methane release has been occurring for thousands of years near the upper limit of methane hydrate stability zone and that seasonal changes in bottom water temperature may be more important than longer-term warming of intermediate waters. However, the existence of hydrates at the upper limit of the gas hydrate zone has been based on modeling results only and gas hydrates have not been sampled successfully. Yearly studies, undertaken during RV Helmer Hanssen cruises as part of CAGE have shown that no significant amount of methane reaches the upper water column and is being released towards the atmosphere from this ca. 400m deep sites. The same is true for a very active seep area at the shelf break in 240m water depth where detailed hydroacoustic studies show fluctuating fluxes between 71 and 114 T/yr in total. Here we focus on studies conducted with the USGS Gas Analysis System (USGS-GAS). Continuous surface water methane and carbon dioxide concentrations and associated data are used to calculate sea-air fluxes with this cavity ring-down spectrometer-based analytical system. Only the shallow seep site (~90 m water depth) had appreciable methane in surface waters. We conducted an exhaustive survey of this site, mapping the full extent of the surface methane plume. To provide three-dimensional constraints, we acquired 65 vertical dissolved methane profiles to delineate the vertical and horizontal extent of the subsurface methane plume. The USGS-GAS data show that methane beyond the 'normal' background fluxes of ~1 µmol m-2 d-1 is elevated at the intensively bubbling shallow seep site (max. 35 µmol m-2 d-1) and near the shallow coastal zone where the fluxes over a large area reach 25 µmol m-2 d-1. Comparing coastal and seep fluxes on

  11. Solar power satellite offshore rectenna study

    NASA Astrophysics Data System (ADS)

    1980-11-01

    It was found that an offshore rectenna is feasible and cost competitive with land rectennas but that the type of rectenna which is suitable for offshore use is quite different from that specified in the present reference system. The result is a nonground plane design which minimizes the weight and greatly reduces the number of costly support towers. This preferred design is an antenna array consisting of individually encapsulated dipoles with reflectors supported on feed wires. Such a 5 GW rectenna could be built at a 50 m water depth site to withstand hurricane and icing conditions for a one time cost of 5.7 billion dollars. Subsequent units would be about 1/3 less expensive. The east coast site chosen for this study represents an extreme case of severe environmental conditions. More benign and more shallow water sites would result in lower costs. Secondary uses such as mariculture appear practical with only minor impact on the rectenna design. The potential advantages of an offshore rectenna, such as no land requirements, removal of microwave radiation from populated areas and minimal impact on the local geopolitics argue strongly that further investigation of the offshore rectenna should be vigorously pursued.

  12. Solar power satellite offshore rectenna study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    It was found that an offshore rectenna is feasible and cost competitive with land rectennas but that the type of rectenna which is suitable for offshore use is quite different from that specified in the present reference system. The result is a nonground plane design which minimizes the weight and greatly reduces the number of costly support towers. This preferred design is an antenna array consisting of individually encapsulated dipoles with reflectors supported on feed wires. Such a 5 GW rectenna could be built at a 50 m water depth site to withstand hurricane and icing conditions for a one time cost of 5.7 billion dollars. Subsequent units would be about 1/3 less expensive. The east coast site chosen for this study represents an extreme case of severe environmental conditions. More benign and more shallow water sites would result in lower costs. Secondary uses such as mariculture appear practical with only minor impact on the rectenna design. The potential advantages of an offshore rectenna, such as no land requirements, removal of microwave radiation from populated areas and minimal impact on the local geopolitics argue strongly that further investigation of the offshore rectenna should be vigorously pursued.

  13. Are seabirds foraging for unpredictable resources?

    NASA Astrophysics Data System (ADS)

    Weimerskirch, Henri

    2007-02-01

    It is generally assumed that the extreme life history traits of pelagic seabirds, such as low fecundity or slow growth of chicks, result from the difficulties obtaining energy at sea from unpredictable and patchily distributed resources. However, little information on seabird prey distribution and availability exists to sustain this widely accepted hypothesis. Using tracking studies of 68 sub-populations of flying seabirds, I examine whether it is possible to gain information on the predictability of their marine resources. Because prey are clustered from fine to large scale in nested unities, from swarms to patches and concentrations of patches, it is important to take into account spatial scale. In temperate and polar regions, at large and meso-scales, seabirds appear to have a good knowledge of the location and concentrations of patches and generally use a commuting type of trip to reach foraging zones. Predictability appears to be high at large and meso-scales, with individuals from each sub-population heading in a particular direction from the colony to reach favoured habitats of known enhanced productivity such as shelf edges, frontal zones, upwellings. Within these mesoscale features, the animals use an area-restricted search behaviour to search for patches and swarms at finer scales. Using information on foraging site fidelity of individual birds, I show that differences in predictability at coarse scales are related to the distance and time spent foraging, and in particular to the specific types of foraging habitat. Some habitats appear to be more predictable than others: birds return consistently to the same coarse-scale sectors on shelf edges, whereas predictability is low in oceanic waters, even in frontal zones. Preliminary results on tropical species suggest that the environment here is less predictable in tropic than in temperate or polar zones. This review highlights that patchiness and predictability of marine resources are complex notions

  14. 77 FR 5552 - Commercial Leasing for Wind Power on the Outer Continental Shelf Offshore Maryland-Call for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

    ... incentivize offshore wind energy development. While a state may promote such development through activities... evaluate and determine areas of the OCS that may be suitable for offshore wind energy development. This... to consider when moving forward with its offshore wind energy leasing process. Since 2009,...

  15. Foraging distance and home range of Cassin's Auklets nesting at two colonies in the California Channel Islands

    USGS Publications Warehouse

    Adams, Josh; Takekawa, John Y.; Carter, Harry R.

    2004-01-01

    We radio-marked 99 Cassin's Auklets (Ptychoramphus aleuticus) nesting at two colonies, Prince Island and Scorpion Rock, separated by 90 km in the California Channel Islands to quantify foraging distance, individual home-range area, and colony-based foraging areas during three consecutive breeding seasons. Auklets generally foraged < 30 km from each colony in all years. Core foraging areas (50% fixed kernel) from Prince Island in 1999-2001 were north to northeast of the colony over the insular shelf near the shelfbreak. Core foraging areas from Scorpion Rock in 2000-2001 occurred in two focal areas: the Anacapa Passage, a narrow interisland passage adjacent to the colony, and over the southeastern Santa Barbara Channel. During 2000, intercolony foraging areas overlapped by 10%; however, auklets from each colony used the overlapping area at different times. Equivalent-sample-size resampling indicated Prince Island foraging area (1216 ?? 654 km2) was twice that of Scorpion Rock (598 ?? 204 km2). At Prince Island, mean individual distances, home-range areas, and colony-based activity areas were greater for females than males, especially during 2001. At Prince Island, core foraging areas of females and males, pooled separately, overlapped by 63% in 1999 and 2000, and by 35% in 2001. Postbreeding auklets from both colonies dispersed northward and moved to active upwelling centers off central California, coincident with decreased upwelling and sea-surface warming throughout the Santa Barbara Channel.

  16. Do crabeater seals forage cooperatively?

    NASA Astrophysics Data System (ADS)

    Gales, Nicholas J.; Fraser, William R.; Costa, Daniel P.; Southwell, Colin

    2004-08-01

    Crabeater seals are abundant pack-ice predators that feed almost exclusively on krill. They have a circumpolar distribution and are generally sighted hauled out on ice floes alone or in pairs. Here we report our observations of a sighting of 150-200 crabeater seals, which were synchronised in their diving and surfacing behaviour, along with a summary of similar observations from western Antarctica of large groups of crabeater seals in synchronous dive cycles. We report on the low frequency of sightings of such groups during Antarctic pack-ice seal surveys in eastern (Greater) Antarctica. We examine plausible hypotheses to explain these observations, and suggest this behaviour is likely to represent some form of cooperative foraging behaviour, whereby a net advantage in individual energy intake rates is conferred to each seal. Current research on crabeater seal foraging using satellite-linked dive recorders is unlikely to provide sufficiently fine-scale data to examine this hypothesis. Nor will this approach indicate if a seal is foraging with conspecifics. The use of remote or animal-borne camera systems is more likely to provide an insight into fine-scale foraging tactics, as well as the possible, occasional use of cooperative foraging strategies.

  17. Food limitation of sea lion pups and the decline of forage off central and southern California.

    PubMed

    McClatchie, Sam; Field, John; Thompson, Andrew R; Gerrodette, Tim; Lowry, Mark; Fiedler, Paul C; Watson, William; Nieto, Karen M; Vetter, Russell D

    2016-03-01

    California sea lions increased from approximately 50 000 to 340 000 animals in the last 40 years, and their pups are starving and stranding on beaches in southern California, raising questions about the adequacy of their food supply. We investigated whether the declining sea lion pup weight at San Miguel rookery was associated with changes in abundance and quality of sardine, anchovy, rockfish and market squid forage. In the last decade off central California, where breeding female sea lions from San Miguel rookery feed, sardine and anchovy greatly decreased in biomass, whereas market squid and rockfish abundance increased. Pup weights fell as forage food quality declined associated with changes in the relative abundances of forage species. A model explained 67% of the variance in pup weights using forage from central and southern California and 81% of the variance in pup weights using forage from the female sea lion foraging range. A shift from high to poor quality forage for breeding females results in food limitation of the pups, ultimately flooding animal rescue centres with starving sea lion pups. Our study is unusual in using a long-term, fishery-independent dataset to directly address an important consequence of forage decline on the productivity of a large marine predator. Whether forage declines are environmentally driven, are due to a combination of environmental drivers and fishing removals, or are due to density-dependent interactions between forage and sea lions is uncertain. However, declining forage abundance and quality was coherent over a large area (32.5-38° N) for a decade, suggesting that trends in forage are environmentally driven.

  18. Food limitation of sea lion pups and the decline of forage off central and southern California

    PubMed Central

    McClatchie, Sam; Field, John; Thompson, Andrew R.; Gerrodette, Tim; Lowry, Mark; Fiedler, Paul C.; Watson, William; Nieto, Karen M.; Vetter, Russell D.

    2016-01-01

    California sea lions increased from approximately 50 000 to 340 000 animals in the last 40 years, and their pups are starving and stranding on beaches in southern California, raising questions about the adequacy of their food supply. We investigated whether the declining sea lion pup weight at San Miguel rookery was associated with changes in abundance and quality of sardine, anchovy, rockfish and market squid forage. In the last decade off central California, where breeding female sea lions from San Miguel rookery feed, sardine and anchovy greatly decreased in biomass, whereas market squid and rockfish abundance increased. Pup weights fell as forage food quality declined associated with changes in the relative abundances of forage species. A model explained 67% of the variance in pup weights using forage from central and southern California and 81% of the variance in pup weights using forage from the female sea lion foraging range. A shift from high to poor quality forage for breeding females results in food limitation of the pups, ultimately flooding animal rescue centres with starving sea lion pups. Our study is unusual in using a long-term, fishery-independent dataset to directly address an important consequence of forage decline on the productivity of a large marine predator. Whether forage declines are environmentally driven, are due to a combination of environmental drivers and fishing removals, or are due to density-dependent interactions between forage and sea lions is uncertain. However, declining forage abundance and quality was coherent over a large area (32.5–38° N) for a decade, suggesting that trends in forage are environmentally driven. PMID:27069651

  19. Offshore underbalanced drilling system could revive field developments. Part 2: Making this valuable reservoir drilling/completion technique work on a conventional offshore drilling platform

    SciTech Connect

    Nessa, D.O.; Tangedahl, M.J.; Saponja, J.

    1997-10-01

    Part 1, presented in the July issue, discussed the emerging trend to move underbalanced drilling (UBD) operations into the offshore arena, following its successful application in many onshore areas. This concluding article delves into the details of applying UBD offshore. Starting with advantages the technique offers in many maturing or complex/marginal prospects, the UBD system for offshore platforms use is described. This involves conversion of the conventional rotary system, use of rotating diverters, design of the surface fluid separation system and the necessary gas (nitrogen or natural gas) injection system to lighten the fluid column. Commonly faced operational challenges for offshore UBD are listed along with recommended solutions.

  20. 33 CFR 147.T08-849 - DEEPWATER HORIZON Mobile Offshore Drilling Unit Safety Zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Drilling Unit Safety Zone. 147.T08-849 Section 147.T08-849 Navigation and Navigable Waters COAST GUARD... DEEPWATER HORIZON Mobile Offshore Drilling Unit Safety Zone. (a) Location. All areas within 500 meters (1640... area surrounds the DEEPWATER HORIZON, a Mobile Offshore Drilling Unit (MODU), that sank in...

  1. Offshore oil and the coastline

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    A radical, accelerated 5-year plan to offer 875 million acres (of which 20 million could actually be leased for oil and gas extraction purposes) on the outer continental shelf (OCS) could result in the release of large volumes of drilling wastes and spillage (Environ. Sci. Tech., Nov. 1981). The actual leasing, under the 5-year plan proposed by Secretary of the Interior James G. Watt, could amount to 4-5 million acres per year—about 10 times as much, on the average, as had been leased over the past 25 years. Regulations on the environmental effects may be less complicated yet more effective in that impact statements will cover large areas instead of the tract-by-tract statements now required. A number of the new offshore leasing areas, for example, the Alaska Coast (Cook Inlet, Beaufort Bay, Gulf of Alaska), the Blake Plateau and Baltimore Canyon, and the Georges Bank, are extremely valuable in terms of renewable resources and potentially fragile in terms of environmental conditions. Fishing interests in these areas have produced considerable controversy over the planned sale of petroleum rights.

  2. Cervid forage utilization in noncommercially thinned ponderosa pine forests

    USGS Publications Warehouse

    Gibbs, M.C.; Jenks, J.A.; Deperno, C.S.; Sowell, B.F.; Jenkins, Kurt J.

    2004-01-01

    To evaluate effects of noncommercial thinning, utilization of forages consumed by elk (Cervus elaphus L.), mule deer (Odocoileus hemionus Raf.), and white-tailed deer (Odocoileus virginianus Raf.) was measured in ponderosa pine (Pinus ponderosa P. & C. Lawson) stands in Custer State Park, S. D. Treatments consisted of unthinned (control; 22 to 32 m2/ha basal area), moderately thinned (12 to 22 m2/ha basal area), and heavily thinned (3 to 13 m2/ha basal area) stands of ponderosa pine. During June, July, and August, 1991 and 1992, about 7,000 individual plants were marked along permanent transects and percent-weight-removed by grazing was ocularly estimated. Sample plots were established along transects and plants within plots were clipped to estimate standing biomass. Pellet groups were counted throughout the study area to determine summer habitat use of elk and deer. Diet composition was evaluated using microhistological analysis of fecal samples. Average percent-weight-removed from all marked plants and percent-plants-grazed were used to evaluate forage utilization. Standing biomass of graminoids, shrubs, and forbs increased (P 0.05) across treatments. Forb use averaged less than 5% within sampling periods when measured as percent-weight-removed and percent-of-plants grazed and did not differ among treatments. Results of pellet group surveys indicated that cervids were primarily using meadow habitats. When averaged over the 2 years, forbs were the major forage class in deer diets, whereas graminoids were the major forage class in diets of elk.

  3. Headquarters Expeditionary Troops Task Force 56. Report on Forager

    DTIC Science & Technology

    1944-04-01

    Pacific Ocean Areas, to start preparations for the GYMKHANA -ROADMAKER Operation with a tentative target date of 15 June. Troops participating were to be...designated after completion of then current operations in the MARSHALLS. The plans for FORAGER were a development of those for GYMKHANA -ROADMAKER

  4. Forage characteristics affecting meat goat preferences for forage chicory cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concentration of bitter sesquiterpene lactones (SL), lactucin, lactucopicrin, and 8-deoxylactucin, has been associated with low soil phosphorus fertility and reduced livestock preference for forage chicory (Cichorium intybus L.). We evaluated the effect of cultivar and available soil P (ASP) on mea...

  5. Shedding light on light: benefits of anthropogenic illumination to a nocturnally foraging shorebird.

    PubMed

    Dwyer, Ross G; Bearhop, Stuart; Campbell, Hamish A; Bryant, David M

    2013-03-01

    Intertidal habitats provide important feeding areas for migratory shorebirds. Anthropogenic developments along coasts can increase ambient light levels at night across adjacent inter-tidal zones. Here, we report the effects of elevated nocturnal light levels upon the foraging strategy of a migratory shorebird (common redshank Tringa totanus) overwintering on an industrialised estuary in Northern Europe. To monitor behaviour across the full intertidal area, individuals were located by day and night using VHF transmitters, and foraging behaviour was inferred from inbuilt posture sensors. Natural light was scored using moon-phase and cloud cover information and nocturnal artificial light levels were obtained using geo-referenced DMSP/OLS night-time satellite imagery at a 1-km resolution. Under high illumination levels, the commonest and apparently preferred foraging behaviour was sight-based. Conversely, birds feeding in areas with low levels of artificial light had an elevated foraging time and fed by touch, but switched to visual rather than tactile foraging behaviour on bright moonlit nights in the absence of cloud cover. Individuals occupying areas which were illuminated continuously by lighting from a large petrochemical complex invariably exhibited a visually based foraging behaviour independently of lunar phase and cloud cover. We show that ambient light levels affect the timing and distribution of foraging opportunities for redshank. We argue that light emitted from an industrial complex improved nocturnal visibility. This allowed sight-based foraging in place of tactile foraging, implying both a preference for sight-feeding and enhanced night-time foraging opportunities under these conditions. The study highlights the value of integrating remotely sensed data and telemetry techniques to assess the effect of anthropogenic change upon nocturnal behaviour and habitat use.

  6. Season and landscape composition affect pollen foraging distances and habitat use of honey bees.

    PubMed

    Danner, Nadja; Molitor, Anna Maria; Schiele, Susanne; Härtel, Stephan; Steffan-Dewenter, Ingolf

    2016-09-01

    Honey bees (Apis mellifera L.) show a large variation in foraging distances and use a broad range of plant species as pollen resources, even in regions with intensive agriculture. However, it is unknown how increasing areas of mass-flowering crops like oilseed rape (Brassica napus; OSR) or a decrease of seminatural habitats (SNH) change the temporal and spatial availability of pollen resources for honey bee colonies, and thus foraging distances and frequency in different habitat types. We studied pollen foraging of honey bee colonies in 16 agricultural landscapes with independent gradients of OSR and SNH area within 2 km and used waggle dances and digital geographic maps with major land cover types to reveal the distance and visited habitat type on a landscape level. Mean pollen foraging distance of 1347 decoded bee dances was 1015 m (± 26 m; SEM). In spring, increasing area of flowering OSR within 2 km reduced mean pollen foraging distances from 1324 m to only 435 m. In summer, increasing cover of SNH areas close to the colonies (within 200 m radius) reduced mean pollen foraging distances from 846 to 469 m. Frequency of pollen foragers per habitat type, measured as the number of dances per hour and hectare, was equally high for SNH, grassland, and OSR fields, but lower for other crops and forests. In landscapes with a small proportion of SNH a significantly higher density of pollen foragers on SNH was observed, indicating that pollen resources in such simple agricultural landscapes are more limited. Overall, we conclude that SNH and mass-flowering crops can reduce foraging distances of honey bee colonies at different scales and seasons with possible benefits for the performance of honey bee colonies. Further, mixed agricultural landscapes with a high proportion of SNH reduce foraging densities of honey bees in SNH and thus possible competition for pollen resources.

  7. Submarine landslides hazard offshore Israel

    NASA Astrophysics Data System (ADS)

    Katz, Oded

    2016-04-01

    Submarine landslides pose significant natural hazards. They can damage seafloor infrastructure, such as that used to recover oil and gas or seafloor telecommunication cables, and even generate tsunamis. We recently mapped 447 submarine landslides across the east Mediterranean continental slope, offshore Israel (hereafter the studied area). The mapped landslides are found at water depths of 130 m to 1,000 m and their volume ranges 10-5 - 100 km3. Landslide scars are typically related to a critical slope angle of >4° . Landslides at the northern part of the studied area are spatially associated with fault scarps and are smaller than the ones on the southern part. In this work we evaluate the potential hazard to population and to on- and off- shore facilities posed by submarine landslides across the studied area. We integrate three independent probabilities: (1) the probability for a landslide event of a given volume, based on the size distribution of the mapped landslides; (2) the probability for a landslide event in a given time, based on the reoccurrence time of triggering earthquakes with M >7, and on a 50,000 years general time frame derived from submarine landslides identified across the Mediterranean Sea; (3) the probability for a landslide event in a given area, based on the distribution of slopes exceeding the critical angle. Overall, the fraction of potentially destructive landslides (size > 0.1 km3) is small, 0.05. Thus, considering typical planning time scales of less than 100 years, the calculated hazard is only moderate. The small fraction of landslides with tsunamogenic potential (size > 1 km3), suggests that the hazard for landslide-induced tsunamis along the open slope part of the studied area is small. Landslides in the southern part of the studied area are larger and thus present a somewhat bigger potential source of tsunami waves.

  8. Offshore Fish Community: Ecological Interactions

    EPA Science Inventory

    The offshore (>80 m) fish community of Lake Superior is made up of predominately native species. The most prominent species are deepwater sculpin, kiyi, cisco, siscowet lake trout, burbot, and the exotic sea lamprey. Bloater and shortjaw cisco are also found in the offshore zone...

  9. Combined foraging strategies and soldier behaviour in Nasutitermes aff. coxipoensis (Blattodea: Termitoidea: Termitidae).

    PubMed

    Almeida, Camilla S; Cristaldo, Paulo F; Florencio, Daniela F; Cruz, Nayara G; Santos, Abraão A; Oliveira, Alexandre P; Santana, Alisson S; Ribeiro, Efrem J M; Lima, Ana P S; Bacci, Leandro; Araújo, Ana P A

    2016-05-01

    A range of behavioural strategies and sensory abilities allows animals to minimize costs involved in food search. By building a network of tunnels and presenting a large number of soldiers (i.e., trophically dependent individuals), Nasutitermes spp. termites feature behaviours that imply additional costs during this process. Here we evaluated N. aff. coxipoensis foraging strategies focusing on the role of soldiers during foraging. Field experiments were carried out via nests transplantation to dune areas, and laboratory experiments evaluated termite responses to sternal gland chemical signals from workers and soldiers. N. aff. coxipoensis presented primarily nocturnal foraging. Soldiers typically initiated foraging; however, in established trails, the number of workers was always higher than that of soldiers. The number of trails remained constant over time, while the number of tunnels increased linearly over time. A higher proportion of tunnels originated in surrounding areas than directly from the nests. At observation points with tunnels, there were more stationary than walking soldiers; the opposite was true at observation points without tunnels. In mixed groups, the workers chose to follow soldier chemical signals, and in these groups, soldiers were the first to follow trails. Our results allowed us to identify a not common foraging strategy in termite species; which included the establishment of trails followed by construction of tunnels. Such foraging strategies occur predominantly at night and soldiers play a key role in the foraging process. This foraging strategy reported here seems to be employed to optimize energetic gain.

  10. Complex scaling behavior in animal foraging patterns

    NASA Astrophysics Data System (ADS)

    Premachandra, Prabhavi Kaushalya

    This dissertation attempts to answer questions from two different areas of biology, ecology and neuroscience, using physics-based techniques. In Section 2, suitability of three competing random walk models is tested to describe the emergent movement patterns of two species of primates. The truncated power law (power law with exponential cut off) is the most suitable random walk model that characterizes the emergent movement patterns of these primates. In Section 3, an agent-based model is used to simulate search behavior in different environments (landscapes) to investigate the impact of the resource landscape on the optimal foraging movement patterns of deterministic foragers. It should be noted that this model goes beyond previous work in that it includes parameters such as spatial memory and satiation, which have received little consideration to date in the field of movement ecology. When the food availability is scarce in a tropical forest-like environment with feeding trees distributed in a clumped fashion and the size of those trees are distributed according to a lognormal distribution, the optimal foraging pattern of a generalist who can consume various and abundant food types indeed reaches the Levy range, and hence, show evidence for Levy-flight-like (power law distribution with exponent between 1 and 3) behavior. Section 4 of the dissertation presents an investigation of phase transition behavior in a network of locally coupled self-sustained oscillators as the system passes through various bursting states. The results suggest that a phase transition does not occur for this locally coupled neuronal network. The data analysis in the dissertation adopts a model selection approach and relies on methods based on information theory and maximum likelihood.

  11. Offshore Essaouira basin: Geology and hydrocarbon potential

    SciTech Connect

    Jabour, H.; Ait Salem, A. )

    1991-03-01

    The study area lies in the offshore extension of the onshore Essaouria basin. The Mesozoic development of the Essaouira margin was largely controlled by Late Triassic to Mid-Jurassic rifting and subsequent opening of the Central Atlantic, with the evolution of a typical passive, opening of the Central Atlantic, with the evolution of a typical passive, continental margin. Diapiric salt structure recognized on seismic defines a Late Triassic-Early Jurassic salt basin in the offshore area initiated during early rifting. Subsidence and sea-level rise during Jurassic resulted in carbonate platform development. This was followed during Cretaceous and Tertiary time by the deposition of a prograding siliciclastic system. Only three wells have been drilled in this basin. Although drilled on poorly defined prospects, these wells encountered gas and oil shows. Fairly extensive seismic coverage of good quality data is now available. A study based on an integrated approach involving seismic facies definition and mapping, correlation with well data, identification of the principal control on sedimentation, and basin modeling in conjunction with source rock prediction and maturity modeling has been carried out. Results have shown that hydrocarbon potential in the offshore Essaouira basin has not yet been substantiated by drilling. Attractive structural and stratigraphic prospects exist in the shelf, shelf edge, and the slope, and await confirmation by drilling.

  12. New technology emphasizes international offshore effort

    SciTech Connect

    1997-07-01

    While the offshore industry is focusing its major development efforts on the deeper waters of the US Gulf, West Africa and Brazil, technology has not stood still in the world`s many other established and frontier offshore development areas. These selected items drawn from contributions by UK companies and a major joint-venture development in Eastern Canada emphasize this effort. Included here are: (1) announcement of a major six-field, 3 Tcf gas development off Nova Scotia`s Sable Island and award of two drilling contracts; (2) a comprehensive study of mobile production units in the UK by Smith Rea Energy Analysts; (3) four applications of an option to high-pressure swivels on an FPSO with multiple subsea inlet lines; (4) a contract to supply a DC bus drive for 17 ESPs on Texaco`s Captain field; and (5) review of an environmental study of the Falkland Islands in preparation for exploration activity.

  13. How anthropogenic noise affects foraging.

    PubMed

    Luo, Jinhong; Siemers, Björn M; Koselj, Klemen

    2015-09-01

    The influence of human activity on the biosphere is increasing. While direct damage (e.g. habitat destruction) is relatively well understood, many activities affect wildlife in less apparent ways. Here, we investigate how anthropogenic noise impairs foraging, which has direct consequences for animal survival and reproductive success. Noise can disturb foraging via several mechanisms that may operate simultaneously, and thus, their effects could not be disentangled hitherto. We developed a diagnostic framework that can be applied to identify the potential mechanisms of disturbance in any species capable of detecting the noise. We tested this framework using Daubenton's bats, which find prey by echolocation. We found that traffic noise reduced foraging efficiency in most bats. Unexpectedly, this effect was present even if the playback noise did not overlap in frequency with the prey echoes. Neither overlapping noise nor nonoverlapping noise influenced the search effort required for a successful prey capture. Hence, noise did not mask prey echoes or reduce the attention of bats. Instead, noise acted as an aversive stimulus that caused avoidance response, thereby reducing foraging efficiency. We conclude that conservation policies may seriously underestimate numbers of species affected and the multilevel effects on animal fitness, if the mechanisms of disturbance are not considered.

  14. Breeding for increased forage quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Forage crops have a large number of benefits to society, including ecosystem services such as soil and water conservation, wildlife habitat, and diversification of the agricultural landscape. However, their principal function can only be realized when they are processed through livestock to produce ...

  15. Squirrel Foraging Preferences: Gone Nuts?

    ERIC Educational Resources Information Center

    Darling, Randi A.

    2007-01-01

    This field exercise examines the feeding preferences of Gray Squirrels ("Sciurus carolinensis"). Students present squirrels with a variety of food types in a cafeteria-style arrangement in order to test hypotheses about foraging preferences. This exercise, which is appropriate for introductory biology, ecology, and animal behavior classes, is…

  16. Handling manure on forage crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Manure application to alfalfa (and other perennial forages) is often necessary because of limited application windows during the year and limited land-to-livestock ratios to meet Comprehensive Nutrient Management Plan requirements. Manure applied before alfalfa planting or during production can impr...

  17. Switchgrass for forage and bioenergy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Switchgrass is a native warm-season grass that has been used for hay, forage, and conservation purposes for decades and switchgrass research in Nebraska has been ongoing since 1936. Recently, switchgrass has been identified as a model perennial grass for bioenergy in the Great Plains and Midwest. Si...

  18. Geospatial characteristics of Florida's coastal and offshore environments: Administrative and political boundaries and offshore sand resources

    USGS Publications Warehouse

    Demopoulos, Amanda W.J.; Foster, Ann M.; Jones, Michal L.; Gualtieri, Daniel J.

    2011-01-01

    The Geospatial Characteristics Geopdf of Florida's Coastal and Offshore Environments is a comprehensive collection of geospatial data describing the political and natural resources of Florida. This interactive map provides spatial information on bathymetry, sand resources, military areas, marine protected areas, cultural resources, locations of submerged cables, and shipping routes. The map should be useful to coastal resource managers and others interested in the administrative and political boundaries of Florida's coastal and offshore region. In particular, as oil and gas explorations continue to expand, the map may be used to explore information regarding sensitive areas and resources in the State of Florida. Users of this geospatial database will find that they have access to synthesized information in a variety of scientific disciplines concerning Florida's coastal zone. This powerful tool provides a one-stop assembly of data that can be tailored to fit the needs of many natural resource managers.

  19. Persistence of forage fish ‘hot spots’ and its association with foraging Steller sea lions (Eumetopias jubatus) in southeast Alaska

    NASA Astrophysics Data System (ADS)

    Gende, Scott M.; Sigler, Michael F.

    2006-02-01

    Whereas primary and secondary productivity at oceanic 'hotspots' may be a function of upwelling and temperature fronts, the aggregation of higher-order vertebrates is a function of their ability to search for and locate these areas. Thus, understanding how predators aggregate at these productive foraging areas is germane to the study of oceanic hot spots. We examined the spatial distribution of forage fish in southeast Alaska for three years to better understand Steller sea lion ( Eumetopias jubatus) aggregations and foraging behavior. Energy densities (millions KJ/km 2) of forage fish were orders of magnitude greater during the winter months (November-February), due to the presence of schools of overwintering Pacific herring ( Clupea pallasi). Within the winter months, herring consistently aggregated at a few areas, and these areas persisted throughout the season and among years. Thus, our study area was characterized by seasonally variable, highly abundant but highly patchily distributed forage fish hot spots. More importantly, the persistence of these forage fish hot spots was an important characteristic in determining whether foraging sea lions utilized them. Over 40% of the variation in the distribution of sea lions on our surveys was explained by the persistence of forage fish hot spots. Using a simple spatial model, we demonstrate that when the density of these hot spots is low, effort necessary to locate these spots is minimized when those spots persist through time. In contrast, under similar prey densities but lower persistence, effort increases dramatically. Thus an important characteristic of pelagic hot spots is their persistence, allowing predators to predict their locations and concentrate search efforts accordingly.

  20. Latitudinal Range Influences the Seasonal Variation in the Foraging Behavior of Marine Top Predators

    PubMed Central

    Villegas-Amtmann, Stella; Simmons, Samantha E.; Kuhn, Carey E.; Huckstadt, Luis A.; Costa, Daniel P.

    2011-01-01

    Non-migratory resident species should be capable of modifying their foraging behavior to accommodate changes in prey abundance and availability associated with a changing environment. Populations that are better adapted to change will have higher foraging success and greater potential for survival in the face of climate change. We studied two species of resident central place foragers from temperate and equatorial regions with differing population trends and prey availability associated to season, the California sea lion (Zalophus californianus) (CSL) whose population is increasing and the endangered Galapagos sea lion (Zalophus wollebaeki) (GSL) whose population is declining. To determine their response to environmental change, we studied and compared their diving behavior using time-depth recorders and satellite location tags and their diet by measuring C and N isotope ratios during a warm and a cold season. Based on latitudinal differences in oceanographic productivity, we hypothesized that the seasonal variation in foraging behavior would differ for these two species. CSL exhibited greater seasonal variability in their foraging behavior as seen in changes to their diving behavior, foraging areas and diet between seasons. Conversely, GSL did not change their diving behavior between seasons, presenting three foraging strategies (shallow, deep and bottom divers) during both. GSL exhibited greater dive and foraging effort than CSL. We suggest that during the warm and less productive season a greater range of foraging behaviors in CSL was associated with greater competition for prey, which relaxed during the cold season when resource availability was greater. GSL foraging specialization suggests that resources are limited throughout the year due to lower primary production and lower seasonal variation in productivity compared to CSL. These latitudinal differences influence their foraging success, pup survival and population growth reflected in contrasting population

  1. Walrus foraging marks on the seafloor in Bristol Bay, Alaska: A reconnaissance survey

    USGS Publications Warehouse

    Bornhold, B.D.; Jay, C.V.; McConnaughey, R.; Rathwell, G.; Rhynas, K.; Collins, W.

    2005-01-01

    A reconnaissance sidescan sonar survey in Bristol Bay, Alaska revealed extensive areas of seafloor with features related to walrus foraging. They are similar to those seen in areas such as the outer Bering Sea and Chukchi Sea. Two types of feature were observed: (a) small (??? 1 m diameter) shallow pits, often in clusters ranging in density from 5 pits per hectare to 35 pits per hectare; and, (b) more abundant, narrow, sinuous furrows, typically 5 to 10 m long with some reaching 20 m or more. Most foraging marks were in less than 60 m water depth in areas of sandy seafloor that were smooth, hummocky or characterized by degraded bedforms; the absence of foraging marks in other areas may be related, in part, to their more dynamic nature. The distribution of foraging marks was consistent in a general way with walrus locations from satellite telemetry studies. ?? Springer-Verlag 2005.

  2. Walrus foraging marks on the seafloor in Bristol Bay, Alaska: a reconnaissance survey

    USGS Publications Warehouse

    Bornhold, B.D.; Jay, C.V.; McConnaughey, R.; Rathwell, G.; Rhynas, K.; Collins, W.

    2005-01-01

    A reconnaissance sidescan sonar survey in Bristol Bay, Alaska revealed extensive areas of seafloor with features related to walrus foraging. They are similar to those seen in areas such as the outer Bering Sea and Chukchi Sea. Two types of feature were observed: (a) small (<<1 m diameter) shallow pits, often in clusters ranging in density from 5 to 35 pits per hectare; and, (b) more abundant, narrow, sinuous furrows, typically 5 to 10 m long with some reaching 20 m or more. Most foraging marks were in less than 60 m water depth in areas of sandy seafloor that were smooth, hummocky or characterized by degraded bedforms; the absence of foraging marks in other areas may be related, in part, to their more dynamic nature. The distribution of foraging marks was consistent in a general way with walrus locations from satellite telemetry studies.

  3. Walrus foraging marks on the seafloor in Bristol Bay, Alaska: a reconnaissance survey

    NASA Astrophysics Data System (ADS)

    Bornhold, Brian D.; Jay, Chadwick V.; McConnaughey, Robert; Rathwell, Glenda; Rhynas, Karl; Collins, William

    2005-11-01

    A reconnaissance sidescan sonar survey in Bristol Bay, Alaska revealed extensive areas of seafloor with features related to walrus foraging. They are similar to those seen in areas such as the outer Bering Sea and Chukchi Sea. Two types of feature were observed: (a) small (≪1 m diameter) shallow pits, often in clusters ranging in density from 5 pits per hectare to 35 pits per hectare; and, (b) more abundant, narrow, sinuous furrows, typically 5 to 10 m long with some reaching 20 m or more. Most foraging marks were in less than 60 m water depth in areas of sandy seafloor that were smooth, hummocky or characterized by degraded bedforms; the absence of foraging marks in other areas may be related, in part, to their more dynamic nature. The distribution of foraging marks was consistent in a general way with walrus locations from satellite telemetry studies.

  4. Spatio-temporal foraging patterns of a giant zooplanktivore, the leatherback turtle

    NASA Astrophysics Data System (ADS)

    Fossette, Sabrina; Hobson, Victoria J.; Girard, Charlotte; Calmettes, Beatriz; Gaspar, Philippe; Georges, Jean-Yves; Hays, Graeme C.

    2010-05-01

    Understanding food web functioning through the study of natural bio-indicators may constitute a valuable and original approach. In the context of jellyfish proliferation in many overexploited marine ecosystems studying the spatio-temporal foraging patterns of the giant "jellyvore" leatherback turtle turns out to be particularly relevant. Here we analyzed long-term tracking data to assess spatio-temporal foraging patterns in 21 leatherback turtles during their pluri-annual migration in the Northern Atlantic. Through an analytical approach based on the animal's own motion (independent of currents) and diving behavior distinct zones of high and low foraging success were identified. High foraging success occurred in a sub-equatorial zone spanning the width of the Atlantic and at high (>30°N) latitudes. Between these zones in the centre of North Atlantic gyre there was low foraging success. This "ocean desert" area was traversed at high speed by leatherbacks on their way to more productive areas at higher latitudes. Animals traveled slowly in high foraging success areas and dived shallower (17.2 ± 8.0 km day - 1 and 53.6 ± 33.1 m mean ± SD respectively) than in low foraging success areas (51.0 ± 13.1 km day - 1 and 81.8 ± 56.2 m mean ± SD respectively). These spatio-temporal foraging patterns seem to relatively closely match the main features of the integrated meso-zooplankton distribution in the North Atlantic. Our method of defining high foraging success areas is intuitive and relatively easy to implement but also takes into account the impact of oceanic currents on animal's behavior.

  5. Habitat use and foraging behavior of Townsend's big-eared bat (Corynorhinus townsendii) in coastal California

    USGS Publications Warehouse

    Fellers, Gary M.; Pierson, Elizabeth D.

    2002-01-01

    Radiotracking studies of Townsend's big-eared bat (Corynorhinus townsendii) were conducted in grazed grassland and coastal forest (California bay, Douglas-fir, and redwood) at Point Reyes National Seashore in coastal central California. Radiotagged bats were used to determine the foraging patterns of both female and male bats and to locate alternate roost sites. The animals showed considerable loyalty to their primary roost sites even though the study was conducted after the nursery period had ended, when the bats would normally be dispersing for the season. Foraging patterns differed between male and female bats, with females traveling greater distances than males. Males consistently stayed close to the maternity colony both during day and night. Both sexes flew in the immediate vicinity of vegetation, both when foraging and when traveling from the roost to foraging areas. Foraging activity was concentrated primarily along the edges of riparian vegetation.

  6. Bahrain's offshore banking center

    SciTech Connect

    Gerakis, A.S.; Roncesvalles, O.

    1983-01-01

    The economic effects of Bahrain's schemes for licensing offshore banking units (OBUs) were the immediate response of major international banks and the financial services the banking center has rendered by improving regional money and exchange markets at a time when a Middle East link was needed to service the increasing demand for oil-wealth banking services. Bahrain's leadership also created a favorable climate. Aggressive competition from banks in Kuwait and Saudi Arabia have caused some friction, but informal supervision by the Bahrain Monetary Agency (BMA) should be able to avoid serious difficulty. Bahrain's success required a banking infrastructure, a free-enterprise system, a willingness to maintain banking standards, a country small enough to benefit directly from OBU income, and a gap in nearby competing centers. 39 references, 1 figure, 5 tables. (DCK)

  7. Threshold foraging behavior of baleen whales

    USGS Publications Warehouse

    Piatt, John F.; Methven, David A.

    1992-01-01

    We conducted hydroacoustic surveys for capelin Mallotus villosus in Witless Bay, Newfoundland, Canada, on 61 days during the summers of 1983 to 1985. On 32 of those days in whlch capelin surveys were conducted, we observed a total of 129 baleen whales - Including 93 humpback Megaptera novaeangliae, 31 minke Balaenoptera acutorostrata and 5 fin whales B. phvsalus. Although a few whales were observed when capelin schools were scarce, the majority (96%) of whales were observed when mean daily capelin densities exceeded 5 schools per linear km surveyed (range of means over 3 yr: 0.0 to 14.0 schools km-1). Plots of daily whale abundance (no. h-1 surveyed) vs daily capelin school density (mean no. schools km-1 surveyed) in each summer revealed that baleen whales have a threshold foraging response to capelin density. Thresholds were estimated using a simple itterative step-function model. Foraging thresholds of baleen whales (7.3, 5.0, and 5.8 schools km-1) varied between years in relation to the overall abundance of capelin schools in the study area during summer (means of 7.2, 3.3, and 5.3 schools km-1, respectively).

  8. Western Fisheries Research Center--Forage fish studies in Puget Sound

    USGS Publications Warehouse

    Liedtke, Theresa L.

    2012-01-01

    Researchers at the Western Fisheries Research Center are working with other U.S. Geological Survey (USGS) Centers to better understand the interconnected roles of forage fishes throughout the ecosystem of Puget Sound, Washington. Support for these studies primarily is from the USGS Coastal Habitats in Puget Sound (CHIPS) program, which supports studies of the nearshore areas of Puget Sound. Human perturbations in the nearshore area such as shoreline armoring or urban development can affect the nearshore habitats critical to forage fish.

  9. Habitat Selection and Foraging Behavior of Southern Elephant Seals in the Western Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Huckstadt, L.; Costa, D. P.; McDonald, B. I.; Tremblay, Y.; Crocker, D. E.; Goebel, M. E.; Fedak, M. E.

    2006-12-01

    We examined the foraging behavior of 18 southern elephant seals foraging over two seasons in the Western Antarctic Peninsula. The foraging behavior and habitat utilization of 7 females in 2005 and 12 in 2006 were followed using satellite linked Satellite Relay Data Loggers that measured diving behavior as well collected salinity and temperature profiles as the animals dove. Animals were tagged after the annual molt during February at Cape Shirreff Livngston Island, South Shetland Islands. There was significant interannual variation in the regions of the Southern Ocean used by seals from Livingston Island. In 2005 of the 7 animals tagged one foraged 4700 km due west of the Antarctic Peninsula going as far as 150 W. The remaining females headed south along the Western Antarctic Peninsula bypassing Marguerite Bay moving south along Alexander Island. Three of these animals continued to forage in the pack ice as it developed. On their return trip all females swam past Livingston Island, continuing on to South Georgia Island where they apparently bred in the austral spring. One animal returned to Cape Shirreff to molt and her tag was recovered. During 2006 animals initially followed a similar migratory pattern going south along the Antarctic Peninsula, but unlike 2005 where the majority of the animals remained in the immediate vicinity of the Western Antarctic Peninsula, most of the animals in 2006 moved well to the west foraging as far as the Amundsen Sea. We compared the area restricted search (focal foraging areas) areas of these animals using a newly developed fractal landscape technique that identifies and quantifies areas of intensive search. The fractal analysis of area restricted search shows that the area, distance and coverage (Fractal D) searched were not different between years, while the time spent in the search areas was higher in 2005. Further analysis will examine how the physical properties of the water column as determined from the CTD data derived from

  10. Ice interaction with offshore structures

    SciTech Connect

    Cammaert, A.B.; Muggeridge, D.B.

    1988-01-01

    Oil platforms and other offshore structures being built in the arctic regions must be able to withstand icebergs, ice islands, and pack ice. This reference explain the effect ice has on offshore structures and demonstrates design and construction methods that allow such structures to survive in harsh, ice-ridden environments. It analyzes the characteristics of sea ice as well as dynamic ice forces on structures. Techniques for ice modeling and field testing facilitate the design and construction of sturdy, offshore constructions. Computer programs included.

  11. Southern Elephant Seals Replenish Their Lipid Reserves at Different Rates According to Foraging Habitat

    PubMed Central

    Richard, Gaëtan; Cox, Samantha L.; Picard, Baptiste; Vacquié-Garcia, Jade; Guinet, Christophe

    2016-01-01

    Assessing energy gain and expenditure in free ranging marine predators is difficult. However, such measurements are critical if we are to understand how variation in foraging efficiency, and in turn individual body condition, is impacted by environmentally driven changes in prey abundance and/or accessibility. To investigate the influence of oceanographic habitat type on foraging efficiency, ten post-breeding female southern elephant seals Mirounga leonina (SES) were equipped and tracked with bio-loggers to give continuous information of prey catch attempts, body density and body activity. Variations in these indices of foraging efficiency were then compared between three different oceanographic habitats, delineated by the main frontal structures of the Southern Ocean. Results show that changes in body density are related not only to the number of previous prey catch attempts and to the body activity (at a 6 day lag), but also foraging habitat type. For example, despite a lower daily prey catch attempt rate, SESs foraging north of the sub-Antarctic front improve their body density at a higher rate than individuals foraging south of the sub-Antarctic and polar fronts, suggesting that they may forage on easier to catch and/or more energetically rich prey in this area. Our study highlights a need to understand the influence of habitat type on top predator foraging behaviour and efficiency when attempting a better comprehension of marine ecosystems. PMID:27902786

  12. Southern Elephant Seals Replenish Their Lipid Reserves at Different Rates According to Foraging Habitat.

    PubMed

    Richard, Gaëtan; Cox, Samantha L; Picard, Baptiste; Vacquié-Garcia, Jade; Guinet, Christophe

    2016-01-01

    Assessing energy gain and expenditure in free ranging marine predators is difficult. However, such measurements are critical if we are to understand how variation in foraging efficiency, and in turn individual body condition, is impacted by environmentally driven changes in prey abundance and/or accessibility. To investigate the influence of oceanographic habitat type on foraging efficiency, ten post-breeding female southern elephant seals Mirounga leonina (SES) were equipped and tracked with bio-loggers to give continuous information of prey catch attempts, body density and body activity. Variations in these indices of foraging efficiency were then compared between three different oceanographic habitats, delineated by the main frontal structures of the Southern Ocean. Results show that changes in body density are related not only to the number of previous prey catch attempts and to the body activity (at a 6 day lag), but also foraging habitat type. For example, despite a lower daily prey catch attempt rate, SESs foraging north of the sub-Antarctic front improve their body density at a higher rate than individuals foraging south of the sub-Antarctic and polar fronts, suggesting that they may forage on easier to catch and/or more energetically rich prey in this area. Our study highlights a need to understand the influence of habitat type on top predator foraging behaviour and efficiency when attempting a better comprehension of marine ecosystems.

  13. Dynamics of foraging trails in the Neotropical termite Velocitermes heteropterus (Isoptera: Termitidae).

    PubMed

    Haifig, Ives; Jost, Christian; Fourcassié, Vincent; Zana, Yossi; Costa-Leonardo, Ana Maria

    2015-09-01

    Foraging behavior in termites varies with the feeding habits of each species but often occurs through the formation of well-defined trails that connect the nest to food sources in species that build structured nests. We studied the formation of foraging trails and the change in caste ratio during foraging in the termite Velocitermes heteropterus. This species is widespread in Cerrado vegetation where it builds epigeal nests and forages in open-air at night. Our aim was to understand the processes involved in the formation of foraging trails, from the exploration of new unmarked areas to the recruitment of individuals to food and the stabilization of traffic on the trails, as well as the participation of the different castes during these processes. Foraging trails were videotaped in the laboratory and the videos were then analyzed both manually and automatically to assess the flow of individuals and the caste ratio on the trails as well as to examine the spatial organization of traffic over time. Foraging trails were composed of minor workers, major workers, and soldiers. The flow of individuals on the trails gradually increased from the beginning of the exploration of new areas up to the discovery of the food. The caste ratio remained constant throughout the foraging excursion: major workers, minor workers and soldiers forage in a ratio of 8:1:1, respectively. The speed of individuals was significantly different among castes, with major workers and soldiers being significantly faster than minor workers. Overall, our results show that foraging excursions in V. heteropterus may be divided in three different phases, characterized by individual speeds, differential flows and lane segregation.

  14. Offshore search continues despite disappointments

    SciTech Connect

    Cornitius, T.

    1985-05-01

    Exploration drilling activity in Australia broke records onshore in 1984, but offshore it was a different story. A total of 373 wells were drilled, onshore and offshore, with 266 labeled as wildcats and appraisals. Out of 80 wells drilled offshore last year, 43 were exploratory compared with 49 in 1983; 48 were oil wells, seven were gas, and 25 were dusters. Offshore discoveries included the Talisman 1 off the coast of Western Australia, which tested around 6000 b/d, and Challis 1 in the Timor Sea, which flowed at 5000 b/d. The failure to establish Jabiru in the Timor Sea as a major oil province like Bass Strait was a major disappointment. However, the Challis 1 was a relief since it indicated the presence of a commercial field adjacent to Jabiru.

  15. Forage use to improve environmental sustainability of ruminant production.

    PubMed

    Guyader, J; Janzen, H H; Kroebel, R; Beauchemin, K A

    2016-08-01

    Ruminants raised for meat and milk are important sources of protein in human diets worldwide. Their unique digestive system allows them to derive energy and nourishment from forages, making use of vast areas of grazing lands not suitable for arable cropping or biofuel production and avoiding direct competition for grain that can be used as human food. However, sustaining an ever-growing population of ruminants consuming forages poses a dilemma: while exploiting their ecological niche, forage-fed ruminants produce large amount of enteric methane, a potent greenhouse gas. Resolving this quandary would allow ruminants an expanded role in meeting growing global demands for livestock products. One way around the dilemma is to devise forage-based diets and feeding systems that reduce methane emissions per unit of milk or meat produced. Ongoing research has made significant strides toward this objective. A wider opportunity is to look beyond methane emissions alone and consider all greenhouse gas emissions from the entire livestock-producing system. For example, by raising ruminants in systems using forages, some of the methane emissions can be offset by preserving or enhancing soil carbon reserves, thereby withholding carbon dioxide from the air. Similarly, well-managed systems based on forages may reduce synthetic fertilizer use by more effective use of manure and nitrogen-fixing plants, thereby curtailing nitrous oxide emissions. The potential environmental benefits of forage-based systems may be expanded even further by considering their other ecological benefits, such as conserving biodiversity, improving soil health, enhancing water quality, and providing wildlife habitat. The quandary, then, can be alleviated by managing ruminants within a holistic land-livestock synchrony that considers not only methane emissions but also suppression of other greenhouse gases as well as other ecological benefits. Given the complexity of such systems, there likely are no singular

  16. Foraging currencies, metabolism and behavioural routines.

    PubMed

    Houston, Alasdair I; McNamara, John M

    2014-01-01

    A fundamental issue in foraging theory is whether it is possible to find a simple currency that characterizes foraging behaviour. If such a currency exists, then it is tempting to argue that the selective forces that have shaped the evolution of foraging behaviour have been understood. We review previous work on currencies for the foraging behaviour of an animal that maximizes total energy gained. In many circumstances, it is optimal to maximize a suitably modified form of efficiency. We show how energy gain, predation and damage can be combined in a single currency based on reproductive value. We draw attention to the idea that hard work may have an adverse effect on an animal's condition. We develop a model of optimal foraging over a day when a forager's state consists of its energy reserves and its condition. Optimal foraging behaviour in our model depends on energy reserves, condition and time of day. The pattern of optimal behaviour depends strongly on assumptions about the probability that the forager is killed by a predator. If condition is important, no simple currency characterizes foraging behaviour, but behaviour can be understood in terms of the maximization of reproductive value. It may be optimal to adopt a foraging option that results in a rate of energy expenditure that is less than the rate associated with maximizing efficiency.

  17. 77 FR 30551 - Commercial Renewable Energy Transmission on the Outer Continental Shelf (OCS) Offshore Rhode...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-23

    ... megawatt (MW) offshore wind energy project located in Rhode Island State waters off Block Island to the.... BOEM has coordinated with the Task Force on potential commercial wind energy development within an Area... 30 MW offshore wind energy project located in Rhode Island State waters approximately 2.5...

  18. 33 CFR 100.740 - Annual Offshore Super Series Boat Race; Fort Myers Beach, FL.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. 100.740 Section 100.740 Navigation and Navigable Waters COAST GUARD... Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. (a) Regulated area. (1) The regulated...

  19. 33 CFR 100.740 - Annual Offshore Super Series Boat Race; Fort Myers Beach, FL.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. 100.740 Section 100.740 Navigation and Navigable Waters COAST GUARD... Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. (a) Regulated area. (1) The regulated...

  20. 33 CFR 100.740 - Annual Offshore Super Series Boat Race; Fort Myers Beach, FL.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. 100.740 Section 100.740 Navigation and Navigable Waters COAST GUARD... Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. (a) Regulated area. (1) The regulated...

  1. 33 CFR 100.740 - Annual Offshore Super Series Boat Race; Fort Myers Beach, FL.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. 100.740 Section 100.740 Navigation and Navigable Waters COAST GUARD... Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. (a) Regulated area. (1) The regulated...

  2. 33 CFR 100.740 - Annual Offshore Super Series Boat Race; Fort Myers Beach, FL.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. 100.740 Section 100.740 Navigation and Navigable Waters COAST GUARD... Annual Offshore Super Series Boat Race; Fort Myers Beach, FL. (a) Regulated area. (1) The regulated...

  3. 33 CFR 165.1156 - Safety Zone; Offshore Marine Terminal, El Segundo, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety Zone; Offshore Marine Terminal, El Segundo, CA. 165.1156 Section 165.1156 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... § 165.1156 Safety Zone; Offshore Marine Terminal, El Segundo, CA. (a) Location. The following area is...

  4. Siting Study Framework and Survey Methodology for Marine and Hydrokinetic Energy Projects in Offshore Southeast Florida

    SciTech Connect

    Vinick, Charles

    2011-09-26

    Presentation from the 2011 Water Peer Review in which principal investigator discusses project progess to Investigate areas offshore southeast Florida that appeared most suitable for siting of marine and hydrokinetic energy conversion facilities that may be proposed in the Atlantic Ocean offshore of southeast Florida.

  5. Multidimensional differentiation in foraging resource use during breeding of two sympatric top predators

    NASA Astrophysics Data System (ADS)

    Friedemann, Guilad; Leshem, Yossi; Kerem, Lior; Shacham, Boaz; Bar-Massada, Avi; McClain, Krystaal M.; Bohrer, Gil; Izhaki, Ido

    2016-10-01

    Ecologically-similar species were found to develop specific strategies to partition their resources, leading to niche differentiation and divergence, in order to avoid interspecific competition. Our study determines multi-dimensional differentiation of two sympatric top-predators, long-legged buzzards (LLB) and short-toed eagles (STE), which recently became sympatric during their breeding season in the Judean Foothills, Israel. By combining information from comprehensive diet and movement analyses we found four dimensions of differentiation: (1) Geographic foraging area: LLB tended to forage relatively close to their nests (2.35 ± 0.62 km), while STE forage far from their nest (13.03 ± 2.20 km) (2) Foraging-habitat type: LLBs forage at low natural vegetation, avoiding cultivated fields, whereas STEs forage in cultivated fields, avoiding low natural vegetation; (3) Diurnal dynamics of foraging: LLBs are uniformly active during daytime, whereas STEs activity peaks in the early afternoon; and (4) Food-niche: while both species largely rely on reptiles (47.8% and 76.3% for LLB and STE, respectively), LLB had a more diverse diet and consumed significantly higher percentages of lizards, while STE consumed significantly higher percentages of snakes. Our results suggest that this multidimensional differentiation allows the spatial coexistence of these two dense populations in the study area.

  6. Multidimensional differentiation in foraging resource use during breeding of two sympatric top predators

    PubMed Central

    Friedemann, Guilad; Leshem, Yossi; Kerem, Lior; Shacham, Boaz; Bar-Massada, Avi; McClain, Krystaal M.; Bohrer, Gil; Izhaki, Ido

    2016-01-01

    Ecologically-similar species were found to develop specific strategies to partition their resources, leading to niche differentiation and divergence, in order to avoid interspecific competition. Our study determines multi-dimensional differentiation of two sympatric top-predators, long-legged buzzards (LLB) and short-toed eagles (STE), which recently became sympatric during their breeding season in the Judean Foothills, Israel. By combining information from comprehensive diet and movement analyses we found four dimensions of differentiation: (1) Geographic foraging area: LLB tended to forage relatively close to their nests (2.35 ± 0.62 km), while STE forage far from their nest (13.03 ± 2.20 km); (2) Foraging-habitat type: LLBs forage at low natural vegetation, avoiding cultivated fields, whereas STEs forage in cultivated fields, avoiding low natural vegetation; (3) Diurnal dynamics of foraging: LLBs are uniformly active during daytime, whereas STEs activity peaks in the early afternoon; and (4) Food-niche: while both species largely rely on reptiles (47.8% and 76.3% for LLB and STE, respectively), LLB had a more diverse diet and consumed significantly higher percentages of lizards, while STE consumed significantly higher percentages of snakes. Our results suggest that this multidimensional differentiation allows the spatial coexistence of these two dense populations in the study area. PMID:27725734

  7. Where the offshore search for oil and gas is headed

    SciTech Connect

    King, R.E.

    1980-10-01

    This overview of the world's potential offshore oil and gas frontiers points out that although solutions to technical and political problems have opened up some promising areas for exploration, many key frontier basins have yet to be explored by modern technology. Long-standing disputes between bordering countries over offshore rights have deterred exploration activities in the Malvinas basin off Argentina and in the Gulf of Venezuela. Political problems have also slowed activity in the US Atlantic offshore, where Mesozoic reef trends may be related to Mexico's large oil fields. In Canada's Labrador Sea and Grand Banks, the problems are largely operational because of the inclement weather and threatening icebergs. The thick sediments off northern Norway remain untapped due to the deep water, Arctic conditions, and boundary disputes with the USSR. The main areas of active exploration are the Gulf of Thailand-Penyu-Natuna basin in Southeast Asia and Ireland's Porcupine Bight basin.

  8. Modelling Pasture-based Automatic Milking System Herds: Grazeable Forage Options

    PubMed Central

    Islam, M. R.; Garcia, S. C.; Clark, C. E. F.; Kerrisk, K. L.

    2015-01-01

    One of the challenges to increase milk production in a large pasture-based herd with an automatic milking system (AMS) is to grow forages within a 1-km radius, as increases in walking distance increases milking interval and reduces yield. The main objective of this study was to explore sustainable forage option technologies that can supply high amount of grazeable forages for AMS herds using the Agricultural Production Systems Simulator (APSIM) model. Three different basic simulation scenarios (with irrigation) were carried out using forage crops (namely maize, soybean and sorghum) for the spring-summer period. Subsequent crops in the three scenarios were forage rape over-sown with ryegrass. Each individual simulation was run using actual climatic records for the period from 1900 to 2010. Simulated highest forage yields in maize, soybean and sorghum- (each followed by forage rape-ryegrass) based rotations were 28.2, 22.9, and 19.3 t dry matter/ha, respectively. The simulations suggested that the irrigation requirement could increase by up to 18%, 16%, and 17% respectively in those rotations in El-Niño years compared to neutral years. On the other hand, irrigation requirement could increase by up to 25%, 23%, and 32% in maize, soybean and sorghum based rotations in El-Nino years compared to La-Nina years. However, irrigation requirement could decrease by up to 8%, 7%, and 13% in maize, soybean and sorghum based rotations in La-Nina years compared to neutral years. The major implication of this study is that APSIM models have potentials in devising preferred forage options to maximise grazeable forage yield which may create the opportunity to grow more forage in small areas around the AMS which in turn will minimise walking distance and milking interval and thus increase milk production. Our analyses also suggest that simulation analysis may provide decision support during climatic uncertainty. PMID:25924963

  9. Hybrid offshore structure

    SciTech Connect

    Finn, L.D.; Maus, L.D.

    1986-09-09

    An articulated offshore structure is described for use in a body of water, the structure comprising: a substantially rigid lower section, the lower section extending upwardly from the bottom of the body of water to a pivot point located intermediate the bottom and the surface of the body of water; a compliant upper section extending upwardly from the pivot point to a position at or above the surface of the body of water; pivot means located proximate pivot point, the pivot means interposed between and connected to the lower section and upper section and adapted to permit the upper section to pivot laterally relative to the lower section; torsion means connected to the upper section and the lower section, the torsion means adapted to transmit torsional loads from the upper section to the lower section; the pivot means being positioned above the bottom of the body of water a distance of between about 10 percent and about 50 percent of the total depth of the body of water so as to substantially minimize the weight of the structure while maintaining the flexural vibration period of the structure at or below a preselected maximum flexural vibration period.

  10. Valuation of pollinator forage services provided by Eucalyptus cladocalyx.

    PubMed

    de Lange, Willem J; Veldtman, Ruan; Allsopp, Mike H

    2013-08-15

    We assess the monetary value of forage provisioning services for honeybees as provided by an alien tree species in the Western Cape province of South Africa. Although Eucalyptus cladocalyx is not an officially declared invader, it is cleared on a regular basis along with other invasive Eucalyptus species such as Eucalyptus camaldulensis, and Eucalyptus conferruminata (which have been prioritised for eradication in South Africa). We present some of the trade-offs associated with the clearing of E. cladocalyx by means of a practical example that illustrates a situation where the benefits of the species to certain stakeholders could support the containment of the species in demarcated areas, while allowing clearing outside such areas. Given the absence of market prices for such forage provisioning services, the replacement cost is used to present the value of the loss in forage as provided by E. cladocalyx if the alien tree species is cleared along with invasive alien tree species. Two replacement scenarios formed the basis for our calculations. The first scenario was an artificial diet as replacement for the forage provisioning service, which yielded a direct cost estimate of US$7.5 m per year. The second was based on a Fynbos cultivation/restoration initiative aimed at substituting the forage provisioning service of E. cladocalyx, which yielded a direct cost of US$20.2 m per year. These figures provide estimates of the potential additional cost burden on the beekeeping industry if E. cladocalyx is completely eradicated from the Western Cape. The cost estimates should be balanced against the negative impacts of E. cladocalyx on ecosystem services in order to make an informed decision with regard to appropriate management strategies for this species. The findings therefore serve as useful inputs to balance trade-offs for alien species that are considered as beneficial to some, but harmful to other.

  11. Quantifying the hurricane risk to offshore wind turbines

    PubMed Central

    Rose, Stephen; Jaramillo, Paulina; Small, Mitchell J.; Grossmann, Iris; Apt, Jay

    2012-01-01

    The U.S. Department of Energy has estimated that if the United States is to generate 20% of its electricity from wind, over 50 GW will be required from shallow offshore turbines. Hurricanes are a potential risk to these turbines. Turbine tower buckling has been observed in typhoons, but no offshore wind turbines have yet been built in the United States. We present a probabilistic model to estimate the number of turbines that would be destroyed by hurricanes in an offshore wind farm. We apply this model to estimate the risk to offshore wind farms in four representative locations in the Atlantic and Gulf Coastal waters of the United States. In the most vulnerable areas now being actively considered by developers, nearly half the turbines in a farm are likely to be destroyed in a 20-y period. Reasonable mitigation measures—increasing the design reference wind load, ensuring that the nacelle can be turned into rapidly changing winds, and building most wind plants in the areas with lower risk—can greatly enhance the probability that offshore wind can help to meet the United States’ electricity needs. PMID:22331894

  12. Quantifying the hurricane risk to offshore wind turbines.

    PubMed

    Rose, Stephen; Jaramillo, Paulina; Small, Mitchell J; Grossmann, Iris; Apt, Jay

    2012-02-28

    The U.S. Department of Energy has estimated that if the United States is to generate 20% of its electricity from wind, over 50 GW will be required from shallow offshore turbines. Hurricanes are a potential risk to these turbines. Turbine tower buckling has been observed in typhoons, but no offshore wind turbines have yet been built in the United States. We present a probabilistic model to estimate the number of turbines that would be destroyed by hurricanes in an offshore wind farm. We apply this model to estimate the risk to offshore wind farms in four representative locations in the Atlantic and Gulf Coastal waters of the United States. In the most vulnerable areas now being actively considered by developers, nearly half the turbines in a farm are likely to be destroyed in a 20-y period. Reasonable mitigation measures--increasing the design reference wind load, ensuring that the nacelle can be turned into rapidly changing winds, and building most wind plants in the areas with lower risk--can greatly enhance the probability that offshore wind can help to meet the United States' electricity needs.

  13. Evidence of trapline foraging in honeybees.

    PubMed

    Buatois, Alexis; Lihoreau, Mathieu

    2016-08-15

    Central-place foragers exploiting floral resources often use multi-destination routes (traplines) to maximise their foraging efficiency. Recent studies on bumblebees have showed how solitary foragers can learn traplines, minimising travel costs between multiple replenishing feeding locations. Here we demonstrate a similar routing strategy in the honeybee (Apis mellifera), a major pollinator known to recruit nestmates to discovered food resources. Individual honeybees trained to collect sucrose solution from four artificial flowers arranged within 10 m of the hive location developed repeatable visitation sequences both in the laboratory and in the field. A 10-fold increase of between-flower distances considerably intensified this routing behaviour, with bees establishing more stable and more efficient routes at larger spatial scales. In these advanced social insects, trapline foraging may complement cooperative foraging for exploiting food resources near the hive (where dance recruitment is not used) or when resources are not large enough to sustain multiple foragers at once.

  14. Optimal foraging, not biogenetic law, predicts spider orb web allometry

    NASA Astrophysics Data System (ADS)

    Gregorič, Matjaž; Kiesbüy, Heine C.; Quiñones Lebrón, Shakira G.; Rozman, Alenka; Agnarsson, Ingi; Kuntner, Matjaž

    2013-03-01

    The biogenetic law posits that the ontogeny of an organism recapitulates the pattern of evolutionary changes. Morphological evidence has offered some support for, but also considerable evidence against, the hypothesis. However, biogenetic law in behavior remains underexplored. As physical manifestation of behavior, spider webs offer an interesting model for the study of ontogenetic behavioral changes. In orb-weaving spiders, web symmetry often gets distorted through ontogeny, and these changes have been interpreted to reflect the biogenetic law. Here, we test the biogenetic law hypothesis against the alternative, the optimal foraging hypothesis, by studying the allometry in Leucauge venusta orb webs. These webs range in inclination from vertical through tilted to horizontal; biogenetic law predicts that allometry relates to ontogenetic stage, whereas optimal foraging predicts that allometry relates to gravity. Specifically, pronounced asymmetry should only be seen in vertical webs under optimal foraging theory. We show that, through ontogeny, vertical webs in L. venusta become more asymmetrical in contrast to tilted and horizontal webs. Biogenetic law thus cannot explain L. venusta web allometry, but our results instead support optimization of foraging area in response to spider size.

  15. Optimal foraging, not biogenetic law, predicts spider orb web allometry.

    PubMed

    Gregorič, Matjaž; Kiesbüy, Heine C; Lebrón, Shakira G Quiñones; Rozman, Alenka; Agnarsson, Ingi; Kuntner, Matjaž

    2013-03-01

    The biogenetic law posits that the ontogeny of an organism recapitulates the pattern of evolutionary changes. Morphological evidence has offered some support for, but also considerable evidence against, the hypothesis. However, biogenetic law in behavior remains underexplored. As physical manifestation of behavior, spider webs offer an interesting model for the study of ontogenetic behavioral changes. In orb-weaving spiders, web symmetry often gets distorted through ontogeny, and these changes have been interpreted to reflect the biogenetic law. Here, we test the biogenetic law hypothesis against the alternative, the optimal foraging hypothesis, by studying the allometry in Leucauge venusta orb webs. These webs range in inclination from vertical through tilted to horizontal; biogenetic law predicts that allometry relates to ontogenetic stage, whereas optimal foraging predicts that allometry relates to gravity. Specifically, pronounced asymmetry should only be seen in vertical webs under optimal foraging theory. We show that, through ontogeny, vertical webs in L. venusta become more asymmetrical in contrast to tilted and horizontal webs. Biogenetic law thus cannot explain L. venusta web allometry, but our results instead support optimization of foraging area in response to spider size.

  16. Potential energetic effects of mountain climbers on foraging grizzly bears

    USGS Publications Warehouse

    White, D.; Kendall, K.C.; Picton, H.D.

    1999-01-01

    Most studies of the effects of human disturbance on grizzly bears (Ursus arctos horribilis) have not quantified the energetic effects of such interactions. In this study, we characterized activity budgets of adult grizzly bears as they foraged on aggregations of adult army cutworm moths (Euxoa auxiliaris) in the alpine of Glacier National Park, Montana, during 1992, 1994, and 1995. We compared the activity budgets of climber-disturbed bears to those of undisturbed bears to estimate the energetic impact of climber disturbance. When bears detected climbers, they subsequently spent 53% less time foraging on moths, 52% more time moving within the foraging area, and 23% more time behaving aggressively, compared to when they were not disturbed. We estimated that grizzly bears could consume approximately 40,000 moths/day or 1,700 moths/hour. At 0.44 kcal/moth, disruption of moth feeding cost bears approximately 12 kcal/minute in addition to the energy expended in evasive maneuvers and defensive behaviors. To reduce both climber interruption of bear foraging and the potential for aggressive bear-human encounters, we recommend routing climbers around moth sites used by bears or limiting access to these sites during bear-use periods.

  17. Green crab (Carcinus maenas) foraging efficiency reduced by fast flows.

    PubMed

    Robinson, Elizabeth M; Smee, Delbert L; Trussell, Geoffrey C

    2011-01-01

    Predators can strongly influence prey populations and the structure and function of ecosystems, but these effects can be modified by environmental stress. For example, fluid velocity and turbulence can alter the impact of predators by limiting their environmental range and altering their foraging ability. We investigated how hydrodynamics affected the foraging behavior of the green crab (Carcinus maenas), which is invading marine habitats throughout the world. High flow velocities are known to reduce green crab predation rates and our study sought to identify the mechanisms by which flow affects green crabs. We performed a series of experiments with green crabs to determine: 1) if their ability to find prey was altered by flow in the field, 2) how flow velocity influenced their foraging efficiency, and 3) how flow velocity affected their handling time of prey. In a field study, we caught significantly fewer crabs in baited traps at sites with fast versus slow flows even though crabs were more abundant in high flow areas. This finding suggests that higher velocity flows impair the ability of green crabs to locate prey. In laboratory flume assays, green crabs foraged less efficiently when flow velocity was increased. Moreover, green crabs required significantly more time to consume prey in high velocity flows. Our data indicate that flow can impose significant chemosensory and physical constraints on green crabs. Hence, hydrodynamics may strongly influence the role that green crabs and other predators play in rocky intertidal communities.

  18. Green Crab (Carcinus maenas) Foraging Efficiency Reduced by Fast Flows

    PubMed Central

    Robinson, Elizabeth M.; Smee, Delbert L.; Trussell, Geoffrey C.

    2011-01-01

    Predators can strongly influence prey populations and the structure and function of ecosystems, but these effects can be modified by environmental stress. For example, fluid velocity and turbulence can alter the impact of predators by limiting their environmental range and altering their foraging ability. We investigated how hydrodynamics affected the foraging behavior of the green crab (Carcinus maenas), which is invading marine habitats throughout the world. High flow velocities are known to reduce green crab predation rates and our study sought to identify the mechanisms by which flow affects green crabs. We performed a series of experiments with green crabs to determine: 1) if their ability to find prey was altered by flow in the field, 2) how flow velocity influenced their foraging efficiency, and 3) how flow velocity affected their handling time of prey. In a field study, we caught significantly fewer crabs in baited traps at sites with fast versus slow flows even though crabs were more abundant in high flow areas. This finding suggests that higher velocity flows impair the ability of green crabs to locate prey. In laboratory flume assays, green crabs foraged less efficiently when flow velocity was increased. Moreover, green crabs required significantly more time to consume prey in high velocity flows. Our data indicate that flow can impose significant chemosensory and physical constraints on green crabs. Hence, hydrodynamics may strongly influence the role that green crabs and other predators play in rocky intertidal communities. PMID:21687742

  19. EPA moves to control offshore emissions

    SciTech Connect

    Not Available

    1991-12-09

    This paper reports that except for most of the Gulf Coast, the Environmental Protection Agency proposes to hold all U.S. offshore rigs and platforms within about 28 miles from shore to the same standards as onshore facilities. EPA estimated compliance will cost the oil industry $2.2 million/year for all sources on the Outer Continental Shelf. The rule, the first EPA has proposed to control air pollution from OCS operations, covers drilling and production off Alaska, the Pacific coast states, the Atlantic coast states, and the Florida Gulf Coast. It does not affect OCS areas off Texas, Louisiana, Mississippi, and Alabama.

  20. From the Lab Bench: Is forage quality that complicated?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An article was written to discuss the definition of forage quality. The true definition of forage quality is based on performance of the cattle when the forage serves as the major source of nutrients. However, an estimate of forage quality will be needed before the forage is fed or grazed. Digest...

  1. Factors affecting the foraging behaviour of the European shag: implications for seabird tracking studies.

    PubMed

    Soanes, L M; Arnould, J P Y; Dodd, S G; Milligan, G; Green, J A

    2014-01-01

    Seabird tracking has become an ever more popular tool to aid environmental procedures such as the designation of marine protected areas and environmental impact assessments. However, samples used are usually small and little consideration is given to experimental design and sampling protocol. European shags Phalacrocorax aristotelis were tracked using GPS technology over three breeding seasons and the following foraging trip characteristics: trip duration, trip distance, maximum distance travelled from the colony, size of area used and direction travelled from colony were determined for each foraging trip. The effect of sex, year of study, breeding site, number and age of chicks and the timing of tracking on foraging behaviour were investigated using a General Estimation Equation model. A range of sampling scenarios reflecting likely field sampling were also tested to compare how foraging behaviour differed depending on composition of the sample of birds tracked. Trip distance, trip duration, maximum distance travelled and size of area used were all significantly affected by the breeding site, and the number of chicks a tracked adult was raising. The effect of sex was also seen when examining trip distance, trip duration and the maximum distance travelled. The direction travelled on a foraging trip was also significantly affected by breeding site. This study highlights the importance of sampling regime and the influence that year, sex, age, number of chicks and breeding site can have on the foraging trip characteristics for this coastal feeding seabird. Given the logistical and financial constraints in tracking large numbers of individuals, this study identifies the need for researchers to consider the composition of their study sample to ensure any identified foraging areas are as representative as possible of the whole colony's foraging area.

  2. U.S. Offshore Wind Manufacturing and Supply Chain Development

    SciTech Connect

    Hamilton, Bruce Duncan

    2013-02-22

    agencies, to assist in identifying policies with low effort and high impact (Chapter 3). Section 3.3 provides specific policy examples that have been demonstrated to be effective in removing barriers to development. (c) Current and potential domestic suppliers in the offshore wind market, in evaluating areas of opportunity and understanding requirements for participation (Chapter 4). Section 4.4 provides a step-by-step description of the qualification process that suppliers looking to sell components into a future U.S. offshore wind market will need to follow.

  3. Boa constrictor (Boa constrictor): foraging behavior

    USGS Publications Warehouse

    Sorrell, G.G.; Boback, M.S.; Reed, R.N.; Green, S.; Montgomery, Chad E.; DeSouza, L.S.; Chiaraviglio, M.

    2011-01-01

    Boa constrictor is often referred to as a sit-and-wait or ambush forager that chooses locations to maximize the likelihood of prey encounters (Greene 1983. In Janzen [ed.], Costa Rica Natural History, pp. 380-382. Univ. Chicago Press, Illinois). However, as more is learned about the natural history of snakes in general, the dichotomy between active versus ambush foraging is becoming blurred. Herein, we describe an instance of diurnal active foraging by a B. constrictor, illustrating that this species exhibits a range of foraging behaviors.

  4. Visual Foraging With Fingers and Eye Gaze

    PubMed Central

    Thornton, Ian M.; Smith, Irene J.; Chetverikov, Andrey; Kristjánsson, Árni

    2016-01-01

    A popular model of the function of selective visual attention involves search where a single target is to be found among distractors. For many scenarios, a more realistic model involves search for multiple targets of various types, since natural tasks typically do not involve a single target. Here we present results from a novel multiple-target foraging paradigm. We compare finger foraging where observers cancel a set of predesignated targets by tapping them, to gaze foraging where observers cancel items by fixating them for 100 ms. During finger foraging, for most observers, there was a large difference between foraging based on a single feature, where observers switch easily between target types, and foraging based on a conjunction of features where observers tended to stick to one target type. The pattern was notably different during gaze foraging where these condition differences were smaller. Two conclusions follow: (a) The fact that a sizeable number of observers (in particular during gaze foraging) had little trouble switching between different target types raises challenges for many prominent theoretical accounts of visual attention and working memory. (b) While caveats must be noted for the comparison of gaze and finger foraging, the results suggest that selection mechanisms for gaze and pointing have different operational constraints. PMID:27433323

  5. Visual Foraging With Fingers and Eye Gaze.

    PubMed

    Jóhannesson, Ómar I; Thornton, Ian M; Smith, Irene J; Chetverikov, Andrey; Kristjánsson, Árni

    2016-03-01

    A popular model of the function of selective visual attention involves search where a single target is to be found among distractors. For many scenarios, a more realistic model involves search for multiple targets of various types, since natural tasks typically do not involve a single target. Here we present results from a novel multiple-target foraging paradigm. We compare finger foraging where observers cancel a set of predesignated targets by tapping them, to gaze foraging where observers cancel items by fixating them for 100 ms. During finger foraging, for most observers, there was a large difference between foraging based on a single feature, where observers switch easily between target types, and foraging based on a conjunction of features where observers tended to stick to one target type. The pattern was notably different during gaze foraging where these condition differences were smaller. Two conclusions follow: (a) The fact that a sizeable number of observers (in particular during gaze foraging) had little trouble switching between different target types raises challenges for many prominent theoretical accounts of visual attention and working memory. (b) While caveats must be noted for the comparison of gaze and finger foraging, the results suggest that selection mechanisms for gaze and pointing have different operational constraints.

  6. Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

    USGS Publications Warehouse

    Woodin, M.C.; Michot, T.C.

    2006-01-01

    Redheads, Aythya americana, concentrate in large numbers annually in traditional wintering areas along the western and northern rim of the Gulf of Mexico. Two of these areas are the Laguna Madre of Texas and Chandeleur Sound of Louisiana. We collected data on 54,340 activities from 103 redhead flocks in Texas and 51,650 activities from 57 redhead flocks in Louisiana. Males and females fed similarly, differing neither in levels of feeding (percent of all birds in flock that were feeding) (p>0.90) nor in percentages of birds feeding by diving, tipping, dipping, or gleaning from the surface (p>0.10). The foraging level of redheads in the upper Laguna Madre region was relatively constant throughout two winters. Foraging of redheads in early winter in Louisiana was significantly greater than redhead foraging in the upper Laguna Madre, but by late winter, foraging by redheads in Louisiana had declined to the same level as that shown by redheads foraging in the upper Laguna Madre. The overall foraging level of redheads from Chandeleur Sound was greater (41%) than that of redheads in the upper Laguna Madre (26%), yet it was quite similar to the 46% foraging level reported for redheads from the lower Laguna Madre. Redheads in the upper Laguna Madre region of Texas fed more by diving than did those in the Chandeleur Sound and the lower Laguna Madre. Diving increased in frequency in late winter. Greater reliance by redheads on diving in January and February indicates that the birds altered their foraging to feed in deeper water, suggesting that the large concentrations of redheads staging at this time for spring migration may have displaced some birds to alternative foraging sites. Our results imply that the most likely period for food resources to become limiting for wintering redheads is when they are staging in late winter. ?? Springer 2006.

  7. Individual honey bee (Apis cerana) foragers adjust their fuel load to match variability in forage reward

    PubMed Central

    Tan, Ken; Latty, Tanya; Dong, Shihao; Liu, Xiwen; Wang, Chao; Oldroyd, Benjamin P.

    2015-01-01

    Animals may adjust their behavior according to their perception of risk. Here we show that free-flying honey bee (Apis cerana) foragers mitigate the risk of starvation in the field when foraging on a food source that offers variable rewards by carrying more ‘fuel’ food on their outward journey. We trained foragers to a feeder located 1.2 km from each of four colonies. On average foragers carried 12.7% greater volume of fuel, equivalent to 30.2% more glucose when foraging on a variable source (a random sequence of 0.5, 1.5 and 2.5 M sucrose solution, average sucrose content 1.5 M) than when forging on a consistent source (constant 1.5 M sucrose solution). Our findings complement an earlier study that showed that foragers decrease their fuel load as they become more familiar with a foraging place. We suggest that honey bee foragers are risk sensitive, and carry more fuel to minimize the risk of starvation in the field when a foraging trip is perceived as being risky, either because the forager is unfamiliar with the foraging site, or because the forage available at a familiar site offers variable rewards. PMID:26549746

  8. Offshore Wind Energy Market Overview (Presentation)

    SciTech Connect

    Baring-Gould, I.

    2013-07-01

    This presentation describes the current international market conditions regarding offshore wind, including the breakdown of installation costs, how to reduce costs, and the physical siting considerations considered when planning offshore wind construction. The presentation offers several examples of international existing and planned offshore wind farm sites and compares existing international offshore resources with U.S. resources. The presentation covers future offshore wind trends and cites some challenges that the United States must overcome before it will be able to fully develop offshore wind sites.

  9. Terminology Guideline for Classifying Offshore Wind Energy Resources

    SciTech Connect

    Beiter, Philipp; Musial, Walt

    2016-09-01

    The purpose of this guideline is to establish a clear and consistent vocabulary for conveying offshore wind resource potential and to interpret this vocabulary in terms that are familiar to the oil and gas (O&G) industry. This involves clarifying and refining existing definitions of offshore wind energy resource classes. The terminology developed in this guideline represents one of several possible sets of vocabulary that may differ with respect to their purpose, data availability, and comprehensiveness. It was customized to correspond with established offshore wind practices and existing renewable energy industry terminology (e.g. DOE 2013, Brown et al. 2015) while conforming to established fossil resource classification as best as possible. The developers of the guideline recognize the fundamental differences that exist between fossil and renewable energy resources with respect to availability, accessibility, lifetime, and quality. Any quantitative comparison between fossil and renewable energy resources, including offshore wind, is therefore limited. For instance, O&G resources are finite and there may be significant uncertainty associated with the amount of the resource. In contrast, aboveground renewable resources, such as offshore wind, do not generally deplete over time but can vary significantly subhourly, daily, seasonally, and annually. The intent of this guideline is to make these differences transparent and develop an offshore wind resource classification that conforms to established fossil resource classifications where possible. This guideline also provides methods to quantitatively compare certain offshore wind energy resources to O&G resource classes for specific applications. Finally, this guideline identifies areas where analogies to established O&G terminology may be inappropriate or subject to misinterpretation.

  10. Offshore Benin, a classic passive margin

    SciTech Connect

    Mathalone, J.M.P. )

    1991-03-01

    Offshore Benin comprises a narrow east-west continental shelf, some 30 km wide. A sharp shelf break running parallel to the coast borders the shelf, whereupon water depths rapidly increase to over 7000 ft. The area lies within the Dahomey Embayment, one of a series of Cretaceous and younger basins lining the coast of Africa that owe their inception to the Late Mesozoic break-up of the Gondwanaland Continent. The basin extends some 100 km inland, but sedimentary section is thin onshore compared to a maximum of 20,000 ft of sediment offshore. Initial sedimentation in this basin was of Neocomian alluvial and lacustrine clastics. These were deposited in east-west-trending narrow half-grabens associated with the initial break up of the South American and African continents. They are covered unconformably by more extensive Albian and Cenomanian transgressive clastics and shallow marine Turonian sandstones which are the main reservoir at Seme, Benin's only oilfield. The Senonian section offshore comprises passive margin deep sea clastic sediments prograding southwards. Very large proximal deep sea channels up to 2500 ft thick are developed in this interval. These channels are associated with excellent petroleum source rocks, averaging 4-5% oil-prone organic carbon, and form the main exploration target in the area when configured in a trap morphology. Seismic data quality is excellent in the region allowing detailed examination of the relationships between the rifted section and later units. In addition, these data illustrate clearly both internal and external morphology of the Senonian proximal deep sea channels.

  11. Review of technology for Arctic offshore oil and gas recovery

    SciTech Connect

    Sackinger, W. M.

    1980-08-01

    The technical background briefing report is the first step in the preparation of a plan for engineering research oriented toward Arctic offshore oil and gas recovery. A five-year leasing schedule for the ice-prone waters of the Arctic offshore is presented, which also shows the projected dates of the lease sale for each area. The estimated peak production rates for these areas are given. There is considerable uncertainty for all these production estimates, since no exploratory drilling has yet taken place. A flow chart is presented which relates the special Arctic factors, such as ice and permafrost, to the normal petroleum production sequence. Some highlights from the chart and from the technical review are: (1) in many Arctic offshore locations the movement of sea ice causes major lateral forces on offshore structures, which are much greater than wave forces; (2) spray ice buildup on structures, ships and aircraft will be considerable, and must be prevented or accommodated with special designs; (3) the time available for summer exploratory drilling, and for deployment of permanent production structures, is limited by the return of the pack ice. This time may be extended by ice-breaking vessels in some cases; (4) during production, icebreaking workboats will service the offshore platforms in most areas throughout the year; (5) transportation of petroleum by icebreaking tankers from offshore tanker loading points is a highly probable situation, except in the Alaskan Beaufort; and (6) Arctic pipelines must contend with permafrost, making instrumentation necessary to detect subtle changes of the pipe before rupture occurs.

  12. Retinal Ganglion Cell Topography of Five Species of Ground-Foraging Birds

    PubMed Central

    Dolan, Tracy; Fernández-Juricic, Esteban

    2010-01-01

    Birds that forage on the ground have been studied extensively in relation to behavioral trade-offs between foraging and scanning for predators; however, we know little about the topography of their retinas, which can influence how they gather visual information. We characterized the density of retinal ganglion cells across the retina and estimated visual acuity of four Passeriformes (European starling Sturnus vulgaris, brown-headed cowbird Molothrus ater, house sparrow Passer domesticus, house finch Carpodacus mexicanus) and one Columbiforme (mourning dove Zenaida macroura) that forage on the ground. We used cresyl violet to stain retinal ganglion cells and estimated visual acuity based on cell density and eye size. All species contained a single area centralis, where cell densities were >20,000 cells/mm2. The proportion of the retina that fell in each of five cell density ranges varied between species. European starlings and house finches had the largest area of high cell density, mourning doves had the smallest. The largest proportion of the retina (>35%) of brown-headed cowbird and house sparrow was in the second-lowest cell density range. Considering the 25th percentile of highest cell densities, house finches and European starlings showed the highest cell densities and mourning doves the lowest. Estimated visual acuity increased from house finch, house sparrow, brown-headed cowbird, European starling to mourning dove, and was associated with both retinal area and cell density. Our findings suggest that these ground foragers do not have highly specialized retinas in relation to other types of foragers (e.g. tree foragers), probably because foraging on seeds and insects from the ground is not as visually demanding; however, the studied species showed variability in retinal topography that may be related to foraging techniques, eye size constraints, and size of the area centralis. PMID:20516656

  13. Wetland selection by breeding and foraging black terns in the Prairie Pothole Region of the United States

    USGS Publications Warehouse

    Steen, Valerie A.; Powell, Abby N.

    2012-01-01

    We examined wetland selection by the Black Tern (Chlidonias niger), a species that breeds primarily in the prairie pothole region, has experienced population declines, and is difficult to manage because of low site fidelity. To characterize its selection of wetlands in this region, we surveyed 589 wetlands throughout North and South Dakota. We documented breeding at 5% and foraging at 17% of wetlands. We created predictive habitat models with a machine-learning algorithm, Random Forests, to explore the relative role of local wetland characteristics and those of the surrounding landscape and to evaluate which characteristics were important to predicting breeding versus foraging. We also examined area-dependent wetland selection while addressing the passive sampling bias by replacing occurrence of terns in the models with an index of density. Local wetland variables were more important than landscape variables in predictions of occurrence of breeding and foraging. Wetland size was more important to prediction of foraging than of breeding locations, while floating matted vegetation was more important to prediction of breeding than of foraging locations. The amount of seasonal wetland in the landscape was the only landscape variable important to prediction of both foraging and breeding. Models based on a density index indicated that wetland selection by foraging terns may be more area dependent than that by breeding terns. Our study provides some of the first evidence for differential breeding and foraging wetland selection by Black Terns and for a more limited role of landscape effects and area sensitivity than has been previously shown.

  14. Foraging flexibility and search patterns are unlinked during breeding in a free-ranging seabird.

    PubMed

    Shoji, Akiko; Aris-Brosou, Stéphane; Owen, Ellie; Bolton, Mark; Boyle, Dave; Fayet, Annette; Dean, Ben; Kirk, Holly; Freeman, Robin; Perrins, Chris; Guilford, Tim

    In order to maximize foraging efficiency in a varying environment, predators are expected to optimize their search strategy. Environmental conditions are one important factor affecting these movement patterns, but variations in breeding constraints (self-feeding vs. feeding young and self-feeding) during different breeding stages (incubation vs. chick-rearing) are often overlooked, so that the mechanisms responsible for such behavioral shifts are still unknown. Here, to test how search patterns are affected at different breeding stages and to explore the proximate causes of these variations, we deployed data loggers to record both position (global positioning system) and dive activity (time-depth recorders) of a colonial breeding seabird, the razorbill Alca torda. Over a period of 3 years, our recordings of 56 foraging trips from 18 breeders show that while there is no evidence for individual route fidelity, razorbills exhibit higher foraging flexibility during incubation than during chick rearing, when foraging becomes more focused on an area of high primary productivity. We further show that this behavioral shift is not due to a shift in search patterns, as reorientations during foraging are independent of breeding stage. Our results suggest that foraging flexibility and search patterns are unlinked, perhaps because birds can read cues from their environment, including conspecifics, to optimize their foraging efficiency.

  15. 47 CFR 22.1007 - Channels for offshore radiotelephone systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... located in the specified geographical zones that provide offshore radiotelephone service. All channels have a bandwidth of 20 kHz and are designated by their center frequencies in MegaHertz. (a) Zone A—Southern Louisiana. The geographical area in Zone A is bounded as follows: From longitude W.87°45′ on...

  16. 47 CFR 22.1007 - Channels for offshore radiotelephone systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... located in the specified geographical zones that provide offshore radiotelephone service. All channels have a bandwidth of 20 kHz and are designated by their center frequencies in MegaHertz. (a) Zone A—Southern Louisiana. The geographical area in Zone A is bounded as follows: From longitude W.87°45′ on...

  17. 47 CFR 22.1007 - Channels for offshore radiotelephone systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... located in the specified geographical zones that provide offshore radiotelephone service. All channels have a bandwidth of 20 kHz and are designated by their center frequencies in MegaHertz. (a) Zone A—Southern Louisiana. The geographical area in Zone A is bounded as follows: From longitude W.87°45′ on...

  18. Offshore finfish mariculture in the Strait of Juan de Fuca

    SciTech Connect

    Rensel, Jack; Kiefer, Dale; Forster, John R.; Woodruff, Dana L.; Evans, Nathan R.

    2007-10-07

    Finfish mariculture has existed in the U.S. Pacific Northwest for over thirty years, but for the past 15 years most effort has focused on culture of Atlantic salmon in protected, inshore cage sites. The Strait of Juan de Fuca (the "Strait") is a large area with relatively sparce shoreline development and several apparent advantages for mariculture using offshore technology.

  19. Virginia Offshore Wind Cost Reduction Through Innovation Study (VOWCRIS) (Poster)

    SciTech Connect

    Maples, B.; Campbell, J.; Arora, D.

    2014-10-01

    The VOWCRIS project is an integrated systems approach to the feasibility-level design, performance, and cost-of-energy estimate for a notional 600-megawatt offshore wind project using site characteristics that apply to the Wind Energy Areas of Virginia, Maryland and North Carolina.

  20. California State Waters Map Series: offshore of Salt Point, California

    USGS Publications Warehouse

    Johnson, Samuel Y.; Dartnell, Peter; Golden, Nadine E.; Hartwell, Stephen R.; Erdey, Mercedes D.; Greene, H. Gary; Cochrane, Guy R.; Kvitek, Rikk G.; Manson, Michael W.; Endris, Charles A.; Dieter, Bryan E.; Watt, Janet T.; Krigsman, Lisa M.; Sliter, Ray W.; Lowe, Erik N.; Chinn, John L.; Johnson, Samuel Y.; Cochran, Susan A.

    2015-01-01

    Potential marine benthic habitats in the Offshore of Salt Point map area include unconsolidated continental shelf sediments, mixed continental shelf substrate, and hard continental shelf substrate. Rocky-shelf outcrops and rubble are considered to be promising potential habitats for rockfish and lingcod, both of which are recreationally and commercially important species.

  1. Amygdala Signaling during Foraging in a Hazardous Environment

    PubMed Central

    Amir, Alon; Lee, Seung-Chan; Headley, Drew B.; Herzallah, Mohammad M.

    2015-01-01

    We recorded basolateral amygdala (BL) neurons in a seminaturalistic foraging task. Rats had to leave their nest to retrieve food in an elongated arena inhabited by a mechanical predator. There were marked trial-to-trial variations in behavior. After poking their head into the foraging arena and waiting there for a while, rats either retreated to their nest or initiated foraging. Before initiating foraging, rats waited longer on trials that followed failed than successful trials indicating that prior experience influenced behavior. Upon foraging initiation, most principal cells (Type-1) reduced their firing rate, while in a minority (Type-2) it increased. When rats aborted foraging, Type-1 cells increased their firing rates, whereas in Type-2 cells it did not change. Surprisingly, the opposite activity profiles of Type-1 and Type-2 units were also seen in control tasks devoid of explicit threats or rewards. The common correlate of BL activity across these tasks was movement velocity, although an influence of position was also observed. Thus depending on whether rats initiated movement or not, the activity of BL neurons decreased or increased, regardless of whether threat or rewards were present. Therefore, BL activity not only encodes threats or rewards, but is closely related to behavioral output. We propose that higher order cortical areas determine task-related changes in BL activity as a function of reward/threat expectations and internal states. Because Type-1 and Type-2 cells likely form differential connections with the central amygdala (controlling freezing), this process would determine whether movement aimed at attaining food or exploration is suppressed or facilitated. SIGNIFICANCE STATEMENT For decades, amygdala research has been dominated by pavlovian and operant conditioning paradigms. This work has led to the view that amygdala neurons signal threats or rewards, in turn causing defensive or approach behaviors. However, the artificial circumstances of

  2. Space use and resource selection by foraging Indiana bats at the northern edge of their distribution

    USGS Publications Warehouse

    Jachowski, David S.; Johnson, Joshua B.; Dobony, Christopher A.; Edwards, John W.; Ford, W. Mark

    2014-01-01

    Despite 4 decades of conservation concern, managing endangered Indiana bat (Myotis sodalis) populations remains a difficult wildlife resource issue facing natural resource managers in the eastern United States. After small signs of population recovery, the recent emergence of white-nose syndrome has led to concerns of local and/or regional extirpation of the species. Where Indiana bats persist, retaining high-quality foraging areas will be critical to meet physiological needs and ensure successful recruitment and overwinter survival. However, insight into foraging behavior has been lacking in the Northeast of the USA. We radio-tracked 12 Indiana bats over 2 summers at Fort Drum, New York, to evaluate factors influencing Indiana bat resource selection during night-time foraging. We found that foraging space use decreased 2% for every 100 m increase in distance to water and 6% for every 100 m away from the forest edge. This suggests high use of riparian areas in close proximity to forest and is somewhat consistent with the species’ foraging ecology in the Midwest and upper South. Given the importance of providing access to high-quality foraging areas during the summer maternity season, Indiana bat conservation at the northern extent of the species’ range will be linked to retention of forested habitat in close proximity to riparian zones. 

  3. Evidence of offshore lake trout reproduction in Lake Huron

    USGS Publications Warehouse

    DeSorcie, Timothy J.; Bowen, Charles A.

    2003-01-01

    Six Fathom Bank-Yankee Reef, an offshore reef complex, was an historically important spawning area believed to represent some of the best habitat for the rehabilitation of lake trout Salvelinus namaycush in Lake Huron. Since 1986, lake trout have been stocked on these offshore reefs to reestablish self-sustaining populations. We sampled with beam trawls to determine the abundance of naturally reproduced age-0 lake trout on these offshore reefs during May-July in 1994-1998 and 2000-2002. In total, 123 naturally reproduced lake trout fry were caught at Six Fathom Bank, and 2 naturally reproduced lake trout fry were caught at nearby Yankee Reef. Our findings suggest that this region of Lake Huron contains suitable habitat for lake trout spawning and offers hope that lake trout rehabilitation can be achieved in the main basin of Lake Huron.

  4. Proposing a Formalised Model for Mindful Information Systems Offshoring

    NASA Astrophysics Data System (ADS)

    Costello, Gabriel J.; Coughlan, Chris; Donnellan, Brian; Gadatsch, Andreas

    The central thesis of this chapter is that mathematical economics can provide a novel approach to the examination of offshoring business decisions and provide an impetus for future research in the area. A growing body of research indicates that projected cost savings from IT offshoring projects are not being met. Furthermore, evidence suggests that decision-making processes have been more emotional than rational, and that many offshoring arrangements have been rushed into without adequate analysis of the true costs involved. Building on the concept of mindfulness and mindlessness introduced to the IS literature by Swanson and Ramiller, a cost equation is developed using “deductive reasoning rather than inductive study” in the tradition of mathematical economics. The model endeavours to capture a wide range of both the quantitative and qualitative parameters. Although the economic model is illustrated against the background of a European scenario, the theoretical framework is generic and applicable to organisations in any global location.

  5. Identifying Space Use at Foraging Arena Scale within the Home Ranges of Large Herbivores

    PubMed Central

    Owen-Smith, Norman; Martin, Jodie

    2015-01-01

    An intermediate spatiotemporal scale of food procurement by large herbivores is evident within annual or seasonal home ranges. It takes the form of settlement periods spanning several days or weeks during which foraging activity is confined to spatially discrete foraging arenas, separated by roaming interludes. Extended by areas occupied for other activities, these foraging arenas contribute towards generating the home range structure. We delineated and compared the foraging arenas exploited by two African large herbivores, sable antelope (a ruminant) and plains zebra (a non-ruminant), using GPS-derived movement data. We developed a novel approach to specifically delineate foraging arenas based on local change points in distance relative to adjoining clusters of locations, and compared its output with modifications of two published methods developed for home range estimation and residence time estimation respectively. We compared how these herbivore species responded to seasonal variation in food resources and how they differed in their spatial patterns of resource utilization. Sable antelope herds tended to concentrate their space use locally, while zebra herds moved more opportunistically over a wider set of foraging arenas. The amalgamated extent of the foraging arenas exploited by sable herds amounted to 12-30 km2, compared with 22-100 km2 for the zebra herds. Half-day displacement distances differed between settlement periods and roaming interludes, and zebra herds generally shifted further over 12h than sable herds. Foraging arenas of sable herds tended to be smaller than those of zebra, and were occupied for period twice as long, and hence exploited more intensively in days spent per unit area than the foraging arenas of zebra. For sable both the intensity of utilization of foraging arenas and proportion of days spent in foraging arenas relative to roaming interludes declined as food resources diminished seasonally, while zebra showed no seasonal variation

  6. Identifying Space Use at Foraging Arena Scale within the Home Ranges of Large Herbivores.

    PubMed

    Owen-Smith, Norman; Martin, Jodie

    2015-01-01

    An intermediate spatiotemporal scale of food procurement by large herbivores is evident within annual or seasonal home ranges. It takes the form of settlement periods spanning several days or weeks during which foraging activity is confined to spatially discrete foraging arenas, separated by roaming interludes. Extended by areas occupied for other activities, these foraging arenas contribute towards generating the home range structure. We delineated and compared the foraging arenas exploited by two African large herbivores, sable antelope (a ruminant) and plains zebra (a non-ruminant), using GPS-derived movement data. We developed a novel approach to specifically delineate foraging arenas based on local change points in distance relative to adjoining clusters of locations, and compared its output with modifications of two published methods developed for home range estimation and residence time estimation respectively. We compared how these herbivore species responded to seasonal variation in food resources and how they differed in their spatial patterns of resource utilization. Sable antelope herds tended to concentrate their space use locally, while zebra herds moved more opportunistically over a wider set of foraging arenas. The amalgamated extent of the foraging arenas exploited by sable herds amounted to 12-30 km2, compared with 22-100 km2 for the zebra herds. Half-day displacement distances differed between settlement periods and roaming interludes, and zebra herds generally shifted further over 12h than sable herds. Foraging arenas of sable herds tended to be smaller than those of zebra, and were occupied for period twice as long, and hence exploited more intensively in days spent per unit area than the foraging arenas of zebra. For sable both the intensity of utilization of foraging arenas and proportion of days spent in foraging arenas relative to roaming interludes declined as food resources diminished seasonally, while zebra showed no seasonal variation

  7. Offshore Energy Knowledge Exchange Workshop Report

    SciTech Connect

    none,

    2012-04-12

    A report detailing the presentations and topics discussed at the Offshore Energy Knowledge Exchange Workshop, an event designed to bring together offshore energy industry representatives to share information, best practices, and lessons learned.

  8. Sex-Related Differences in the Trade-Off between Foraging and Vigilance in a Granivorous Forager

    PubMed Central

    Powolny, Thibaut; Bretagnolle, Vincent; Aguilar, Astrid; Eraud, Cyril

    2014-01-01

    The relationship between intake rate and food density can provide the foundation for models that predict the spatiotemporal distribution of organisms across a range of resource densities. The functional response, describing the relationship between resource density and intake rate is often interpreted mechanistically as the relationships between times spend searching and handling. While several functional response models incorporate anti-predator vigilance (defined here as an interruption of feeding or some other activity to visually scan the environment, directed mainly towards detecting potential predators), the impacts of environmental factors influencing directly anti-predator vigilance remains unclear. We examined the combined effects of different scenarios of predation risk and food density on time allocation between foraging and anti-predator vigilance in a granivorous species. We experimentally exposed Skylarks to various cover heights and seed densities, and measured individual time budget and pecking and intake rates. Our results indicated that time devoted to different activities varied as a function of both seed density and cover height. Foraging time increased with seed density for all cover heights. Conversely, an increased cover height resulted in a decreased foraging time. Contrary to males, the decreased proportion of time spent foraging did not translate into a foraging disadvantage for females. When vegetation height was higher, females maintained similar pecking and intake rates compared to intermediate levels, while males consistently decreased their energy gain. This difference in anti-predator responses suggests a sexually mediated strategy in the food-safety trade-off: when resource density is high a females would adopt a camouflage strategy while an escape strategy would be adopted by males. In other words, males would leave risky-areas, whereas females would stay when resource density is high. Our results suggest that increased predation

  9. Evolution of the central Walvis Basin / offshore NW Namibia - balancing onshore erosion and offshore sedimentation

    NASA Astrophysics Data System (ADS)

    Henk, A.; Kukulus, M.; Junker, R.

    2003-04-01

    Rifting and break-up of Gondwana in the Late Jurassic / Early Cretaceous led to formation of the South Atlantic. One of the associated passive margins, the Walvis Basin in NW Namibia, is used as a case study to investigate the mass and process balances which link uplift and erosion onshore to contemporaneous subsidence and sedimentation offshore. One of the main objectives of the project is to gain quantitative insights into the feedback mechanisms between surface processes and lithospheric processes during passive margin evolution. Modeling concentrates on a traverse across the central Walvis Basin and adjacent onshore areas. Mass balancing requires a reconstruction of the denudation history and the volumes eroded onshore as well as a quantification of the contemporaneous sedimentary record preserved offshore. In the offshore parts of the study area, seismic sections and well data are available to constrain the post-rift evolution of the Walvis basin. However, as none of the exploration wells has yet reached syn-rift deposits, the early margin evolution has to remain speculative. In the onshore part of the traverse, field evidence and published apatite fission track data are used to reconstruct the erosion history. Comparison of the eroded and deposited volumes and masses, respectively, reveals a misfit of about 50 %, i.e. only half of the sediments observed offshore can be attributed to nearby source areas onshore. This result is supported by provenance analysis on cuttings from an offshore well which indicate that a substantial part of the detritus was derived from sources to the south and transported to the central Walvis Basin by coast-parallel currents. Sediment supply rates derived from reconstruction of the onshore erosion history and subsidence rates based on lithospheric cooling models together with global sea level changes are then used to model quantitatively deposition and stratigraphic architectures of the post-rift succession in the central Walvis

  10. 7 CFR 1437.401 - Forage.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... range management practices for the location necessary to sustain sufficient quality and quantity of the... for the geographical region after consideration of at least two independent assessments of grazed forage acreage conditions. The assessments shall be completed by forage or range specialists in...

  11. 7 CFR 1437.401 - Forage.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... range management practices for the location necessary to sustain sufficient quality and quantity of the... for the geographical region after consideration of at least two independent assessments of grazed forage acreage conditions. The assessments shall be completed by forage or range specialists in...

  12. 7 CFR 1437.401 - Forage.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... range management practices for the location necessary to sustain sufficient quality and quantity of the... for the geographical region after consideration of at least two independent assessments of grazed forage acreage conditions. The assessments shall be completed by forage or range specialists in...

  13. 7 CFR 1437.401 - Forage.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... range management practices for the location necessary to sustain sufficient quality and quantity of the... for the geographical region after consideration of at least two independent assessments of grazed forage acreage conditions. The assessments shall be completed by forage or range specialists in...

  14. Grass vs. legume forages for dairy cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Alfalfa is the primary forage fed to lactating dairy cows; however, there is renewed interest in utilizing grass forages in lactating dairy cow diets particularly because of farm nutrient management issues. Yield and perceived quality is generally lower for grass species compared to legumes while ot...

  15. Polyphenol oxidase activity in annual forage clovers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenol oxidase (PPO)-mediated phenol reactions in red clover (Trifolium pratense L.) bind forage protein and reduce proteolysis, producing beneficial effects on forage protein degradability, silage fermentation, and soil-N cycling. We evaluated PPO activity in seven previously untested annual c...

  16. Increased carrying capacity with perennial forage kochia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carrying capacity can be increased on grass-dominated rangeland pastures by including perennial forage kochia (Kochia prostrata) as one of the plant components. The objectives of the study reported here were to compare the differences of traditional winter pastures versus pastures with forage kochi...

  17. Sorghum as a forage in Wisconsin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growing moderate quality forages that meet, but do not exceed, requirements of dairy replacement heifers is not a common practice in Wisconsin; however, this forage management option would have a positive impact on the dairy industry. It is typical for heifers to gain excessive bodyweight when they ...

  18. Palatability of Forage Chicory Cultivars for Goats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sesquiterpene lactones (SL) in forage chicory (Cichorium intybus L.) may have anthelmintic activity against gastrointestinal parasites in sheep and goats, but have been implicated in poor palatability of forage. We used three levels of soil P fertilization to influence SL concentrations in three cu...

  19. Optimal forager against ideal free distributed prey.

    PubMed

    Garay, József; Cressman, Ross; Xu, Fei; Varga, Zoltan; Cabello, Tomás

    2015-07-01

    The introduced dispersal-foraging game is a combination of prey habitat selection between two patch types and optimal-foraging approaches. Prey's patch preference and forager behavior determine the prey's survival rate. The forager's energy gain depends on local prey density in both types of exhaustible patches and on leaving time. We introduce two game-solution concepts. The static solution combines the ideal free distribution of the prey with optimal-foraging theory. The dynamical solution is given by a game dynamics describing the behavioral changes of prey and forager. We show (1) that each stable equilibrium dynamical solution is always a static solution, but not conversely; (2) that at an equilibrium dynamical solution, the forager can stabilize prey mixed patch use strategy in cases where ideal free distribution theory predicts that prey will use only one patch type; and (3) that when the equilibrium dynamical solution is unstable at fixed prey density, stable behavior cycles occur where neither forager nor prey keep a fixed behavior.

  20. Trade-offs between predation risk and forage differ between migrant strategies in a migratory ungulate.

    PubMed

    Hebblewhite, Mark; Merrill, Evelyn H

    2009-12-01

    Trade-offs between predation risk and forage fundamentally drive resource selection by animals. Among migratory ungulates, trade-offs can occur at large spatial scales through migration, which allows an "escape" from predation, but trade-offs can also occur at finer spatial scales. Previous authors suggest that ungulates will avoid predation risk at the largest scale, although few studies have examined multi-scale trade-offs to test for the relative benefits of risk avoidance across scales. Building on previously developed spatial models of forage and wolf predation risk, we tested for trade-offs at the broad landscape scale and at a finer, within-home-range scale for migratory and non-migratory resident elk (Cervus elaphus) during summer in the Canadian Rockies in Banff National Park (BNP) and adjacent Alberta, Canada. Migration reduced exposure to wolf predation risk by 70% relative to residents at the landscape scale; at the fine scale, migrants used areas that were, on average, 6% higher in forage digestibility. In contrast, by forgoing migration, resident elk were exposed to higher predation risk, but they reduced predation risk at fine scales to only 15% higher than migrants by using areas close to human activity, which wolves avoided. Thus, residents paid for trying to avoid predation risk with lower forage quality. Residents may have been able to compensate, however, by using areas of abundant forage close to human activity where they may have been able to forage more selectively while avoiding predation risk. Human activity effectively decoupled the positive correlation between high forage quality and wolf predation, providing an effective alternate strategy for residents, similar to recent findings in other systems. Although ungulates appear capable of balancing risk and forage at different spatial scales, risk avoidance at large landscape scales may be more effective in the absence of human-caused refugia from predation.

  1. Solar power satellite offshore rectenna study. Final report

    SciTech Connect

    Not Available

    1980-05-01

    Rice University, Brown and Root Development Inc., and Arthur D. Little Inc. have jointly conducted a feasibility study of an offshore rectenna serving the Boston/New York area. We found that an offshore rectenna is feasible and cost competitive with land rectennas but that the type of rectenna which is suitable for offshore use is quite different from that specified in the present reference system. We began by engineering the reference system rectenna to the offshore location. When we estimated costs for the resulting system we found that the cost was prohibitively high. We then searched for modifications to the design which would allow significant cost reduction. The result is a non-ground plane design which minimizes the weight and greatly reduces the number of costly support towers. This preferred design is an antenna array consisting of individually encapsulated dipoles with reflectors or yagis supported on feed wires. We find that such a 5 GW rectenna could be built at a 50 m water depth site to withstand hurricane, winter storm and icing conditions for a one time cost of $5.7 billion. Subsequent units would be about 1/3 less expensive. It is important to note that the east coast site chosen for this study represents an extreme case of severe environmental conditions. More benign and more shallow water sites would result in substantially lower costs. Secondary uses such as mariculture appear practical with only minor impact on the rectenna design. The potential advantages of an offshore rectenna such as no land requirements, removal of microwave radiation from populated areas and minimal impact on the local geopolitics argue strongly that further investigation of the offshore rectenna should be vigorously pursued.

  2. Foraging ecology of Caspian Terns in the Columbia River Estuary, USA

    USGS Publications Warehouse

    Lyons, Donald E.; Roby, D.D.; Collis, K.

    2005-01-01

    Comparisons were made of the foraging ecology of Caspian Terns (Sterna caspia) nesting on two islands in the Columbia River estuary using radio telemetry and observations of prey fed to chicks and mates at each colony. Early in the chick-rearing period, radio-tagged terns nesting at Rice Island (river km 34) foraged mostly in the freshwater zone of the estuary close to the colony, while terns nesting on East Sand Island (river km 8) foraged in the marine or estuarine mixing zones close to that colony. Late in the chick-rearing period, Rice Island terns moved more of their foraging to the two zones lower in the estuary, while East Sand Island terns continued to forage in these areas. Tern diets at each colony corresponded to the primary foraging zone (freshwater vs. marine/ mixing) of radio-tagged individuals: Early in chick-rearing, Rice Island terns relied heavily on juvenile salmonids (Oncorhynchus spp., 71% of identified prey), but this declined late in chick-rearing (46%). East Sand Island terns relied less on salmonids (42% and 16%, early and late in chick-rearing), and instead utilized marine fishes such as Anchovy (Engraulis mordax) and Herring (Clupea pallasi). Throughout chick-rearing, Rice Island terns foraged farther from their colony (median distance: 12.3 km during early chick-rearing and 16.9 km during late chick-rearing) than did East Sand Island terns (9.6 and 7.7 km, respectively). The study leads to the conclusion that Caspian Terns are generalist foragers and make use of the most proximate available forage fish resources when raising young.

  3. Bat guilds, a concept to classify the highly diverse foraging and echolocation behaviors of microchiropteran bats

    PubMed Central

    Denzinger, Annette; Schnitzler, Hans-Ulrich

    2013-01-01

    Throughout evolution the foraging and echolocation behaviors as well as the motor systems of bats have been adapted to the tasks they have to perform while searching and acquiring food. When bats exploit the same class of environmental resources in a similar way, they perform comparable tasks and thus share similar adaptations independent of their phylogeny. Species with similar adaptations are assigned to guilds or functional groups. Habitat type and foraging mode mainly determine the foraging tasks and thus the adaptations of bats. Therefore, we use habitat type and foraging mode to define seven guilds. The habitat types open, edge and narrow space are defined according to the bats' echolocation behavior in relation to the distance between bat and background or food item and background. Bats foraging in the aerial, trawling, flutter detecting, or active gleaning mode use only echolocation to acquire their food. When foraging in the passive gleaning mode bats do not use echolocation but rely on sensory cues from the food item to find it. Bat communities often comprise large numbers of species with a high diversity in foraging areas, foraging modes, and diets. The assignment of species living under similar constraints into guilds identifies patterns of community structure and helps to understand the factors that underlie the organization of highly diverse bat communities. Bat species from different guilds do not compete for food as they differ in their foraging behavior and in the environmental resources they use. However, sympatric living species belonging to the same guild often exploit the same class of resources. To avoid competition they should differ in their niche dimensions. The fine grain structure of bat communities below the rather coarse classification into guilds is determined by mechanisms that result in niche partitioning. PMID:23840190

  4. Plant Trait Assembly Affects Superiority of Grazer's Foraging Strategies in Species-Rich Grasslands

    PubMed Central

    Mládek, Jan; Mládková, Pavla; Hejcmanová, Pavla; Dvorský, Miroslav; Pavlu, Vilém; De Bello, Francesco; Duchoslav, Martin; Hejcman, Michal; Pakeman, Robin J.

    2013-01-01

    Background Current plant – herbivore interaction models and experiments with mammalian herbivores grazing plant monocultures show the superiority of a maximizing forage quality strategy (MFQ) over a maximizing intake strategy (MI). However, there is a lack of evidence whether grazers comply with the model predictions under field conditions. Methodology/Findings We assessed diet selection of sheep (Ovis aries) using plant functional traits in productive mesic vs. low-productivity dry species-rich grasslands dominated by resource-exploitative vs. resource-conservative species respectively. Each grassland type was studied in two replicates for two years. We investigated the first grazing cycle in a set of 288 plots with a diameter of 30 cm, i.e. the size of sheep feeding station. In mesic grasslands, high plot defoliation was associated with community weighted means of leaf traits referring to high forage quality, i.e. low leaf dry matter content (LDMC) and high specific leaf area (SLA), with a high proportion of legumes and the most with high community weighted mean of forage indicator value. In contrast in dry grasslands, high community weighted mean of canopy height, an estimate of forage quantity, was the best predictor of plot defoliation. Similar differences in selection on forage quality vs. quantity were detected within plots. Sheep selected plants with higher forage indicator values than the plot specific community weighted mean of forage indicator value in mesic grasslands whereas taller plants were selected in dry grasslands. However, at this scale sheep avoided legumes and plants with higher SLA, preferred plants with higher LDMC while grazing plants with higher forage indicator values in mesic grasslands. Conclusions Our findings indicate that MFQ appears superior over MI only in habitats with a predominance of resource-exploitative species. Furthermore, plant functional traits (LDMC, SLA, nitrogen fixer) seem to be helpful correlates of forage quality

  5. Foraging Behaviour of Juvenile Female New Zealand Sea Lions (Phocarctos hookeri) in Contrasting Environments

    PubMed Central

    Leung, Elaine S.; Augé, Amélie A.; Chilvers, B. Louise; Moore, Antoni B.; Robertson, Bruce C.

    2013-01-01

    Foragers can show adaptive responses to changes within their environment through morphological and behavioural plasticity. We investigated the plasticity in body size, at sea movements and diving behaviour of juvenile female New Zealand (NZ) sea lions (Phocarctos hookeri) in two contrasting environments. The NZ sea lion is one of the rarest pinnipeds in the world. Most of the species is based at the subantarctic Auckland Islands (AI; considered to be marginal foraging habitat), with a recolonizing population on the Otago Peninsula, NZ mainland (considered to be more optimal habitat). We investigated how juvenile NZ sea lions adjust their foraging behaviour in contrasting environments by deploying satellite-linked platform transmitting terminals (PTTs) and time-depth recorders (TDRs) on 2–3 year-old females at AI (2007–2010) and Otago (2009–2010). Juvenile female NZ sea lions exhibited plasticity in body size and behaviour. Otago juveniles were significantly heavier than AI juveniles. Linear mixed effects models showed that study site had the most important effect on foraging behaviour, while mass and age had little influence. AI juveniles spent more time at sea, foraged over larger areas, and dove deeper and longer than Otago juveniles. It is difficult to attribute a specific cause to the observed contrasts in foraging behaviour because these differences may be driven by disparities in habitat/prey characteristics, conspecific density levels or interseasonal variation. Nevertheless, the smaller size and increased foraging effort of AI juveniles, combined with the lower productivity in this region, support the hypothesis that AI are less optimal habitat than Otago. It is more difficult for juveniles to forage in suboptimal habitats given their restricted foraging ability and lower tolerance for food limitation compared to adults. Thus, effective management measures should consider the impacts of low resource environments, along with changes that can alter food

  6. Foraging behaviour of juvenile female New Zealand sea lions (Phocarctos hookeri) in contrasting environments.

    PubMed

    Leung, Elaine S; Augé, Amélie A; Chilvers, B Louise; Moore, Antoni B; Robertson, Bruce C

    2013-01-01

    Foragers can show adaptive responses to changes within their environment through morphological and behavioural plasticity. We investigated the plasticity in body size, at sea movements and diving behaviour of juvenile female New Zealand (NZ) sea lions (Phocarctos hookeri) in two contrasting environments. The NZ sea lion is one of the rarest pinnipeds in the world. Most of the species is based at the subantarctic Auckland Islands (AI; considered to be marginal foraging habitat), with a recolonizing population on the Otago Peninsula, NZ mainland (considered to be more optimal habitat). We investigated how juvenile NZ sea lions adjust their foraging behaviour in contrasting environments by deploying satellite-linked platform transmitting terminals (PTTs) and time-depth recorders (TDRs) on 2-3 year-old females at AI (2007-2010) and Otago (2009-2010). Juvenile female NZ sea lions exhibited plasticity in body size and behaviour. Otago juveniles were significantly heavier than AI juveniles. Linear mixed effects models showed that study site had the most important effect on foraging behaviour, while mass and age had little influence. AI juveniles spent more time at sea, foraged over larger areas, and dove deeper and longer than Otago juveniles. It is difficult to attribute a specific cause to the observed contrasts in foraging behaviour because these differences may be driven by disparities in habitat/prey characteristics, conspecific density levels or interseasonal variation. Nevertheless, the smaller size and increased foraging effort of AI juveniles, combined with the lower productivity in this region, support the hypothesis that AI are less optimal habitat than Otago. It is more difficult for juveniles to forage in suboptimal habitats given their restricted foraging ability and lower tolerance for food limitation compared to adults. Thus, effective management measures should consider the impacts of low resource environments, along with changes that can alter food

  7. Eating locally: Australasian gannets increase their foraging effort in a restricted range

    PubMed Central

    Angel, Lauren P.; Barker, Sophie; Berlincourt, Maud; Tew, Emma; Warwick-Evans, Victoria; Arnould, John P. Y.

    2015-01-01

    ABSTRACT During the breeding season, seabirds adopt a central place foraging strategy and are restricted in their foraging range by the fasting ability of their partner/chick and the cost of commuting between the prey resources and the nest. Because of the spatial and temporal variability of marine ecosystems, individuals must adapt their behaviour to increase foraging success within these constraints. The at-sea movements, foraging behaviour and effort of the Australasian gannet (Morus serrator) was determined over three sequential breeding seasons of apparent differing prey abundance to investigate how the species adapts to inter-annual fluctuations in food availability. GPS and tri-axial accelerometer data loggers were used to compare the degree of annual variation within two stages of breeding (incubation and chick rearing) at a small gannet colony situated between two larger, nearby colonies. Interestingly, neither males nor females increased the total distance travelled or duration of foraging trip in any breeding stage (P>0.05 in all cases) despite apparent low prey availability. However, consistently within each breeding stage, mean vectorial dynamic body acceleration (an index of energy expenditure) was greater in years of poorer breeding success (increased by a factor of three to eight), suggesting birds were working harder within their range. Additionally, both males and females increased the proportion of a foraging trip spent foraging in a poorer year across both breeding stages. Individuals from this colony may be limited in their ability to extend their range in years of low prey availability due to competition from conspecifics in nearby colonies and, consequently, increase foraging effort within this restricted foraging area. PMID:26369928

  8. Eating locally: Australasian gannets increase their foraging effort in a restricted range.

    PubMed

    Angel, Lauren P; Barker, Sophie; Berlincourt, Maud; Tew, Emma; Warwick-Evans, Victoria; Arnould, John P Y

    2015-09-14

    During the breeding season, seabirds adopt a central place foraging strategy and are restricted in their foraging range by the fasting ability of their partner/chick and the cost of commuting between the prey resources and the nest. Because of the spatial and temporal variability of marine ecosystems, individuals must adapt their behaviour to increase foraging success within these constraints. The at-sea movements, foraging behaviour and effort of the Australasian gannet (Morus serrator) was determined over three sequential breeding seasons of apparent differing prey abundance to investigate how the species adapts to inter-annual fluctuations in food availability. GPS and tri-axial accelerometer data loggers were used to compare the degree of annual variation within two stages of breeding (incubation and chick rearing) at a small gannet colony situated between two larger, nearby colonies. Interestingly, neither males nor females increased the total distance travelled or duration of foraging trip in any breeding stage (P>0.05 in all cases) despite apparent low prey availability. However, consistently within each breeding stage, mean vectorial dynamic body acceleration (an index of energy expenditure) was greater in years of poorer breeding success (increased by a factor of three to eight), suggesting birds were working harder within their range. Additionally, both males and females increased the proportion of a foraging trip spent foraging in a poorer year across both breeding stages. Individuals from this colony may be limited in their ability to extend their range in years of low prey availability due to competition from conspecifics in nearby colonies and, consequently, increase foraging effort within this restricted foraging area.

  9. Optimal web investment in sub-optimal foraging conditions

    NASA Astrophysics Data System (ADS)

    Harmer, Aaron M. T.; Kokko, Hanna; Herberstein, Marie E.; Madin, Joshua S.

    2012-01-01

    Orb web spiders sit at the centre of their approximately circular webs when waiting for prey and so face many of the same challenges as central-place foragers. Prey value decreases with distance from the hub as a function of prey escape time. The further from the hub that prey are intercepted, the longer it takes a spider to reach them and the greater chance they have of escaping. Several species of orb web spiders build vertically elongated ladder-like orb webs against tree trunks, rather than circular orb webs in the open. As ladder web spiders invest disproportionately more web area further from the hub, it is expected they will experience reduced prey gain per unit area of web investment compared to spiders that build circular webs. We developed a model to investigate how building webs in the space-limited microhabitat on tree trunks influences the optimal size, shape and net prey gain of arboricolous ladder webs. The model suggests that as horizontal space becomes more limited, optimal web shape becomes more elongated, and optimal web area decreases. This change in web geometry results in decreased net prey gain compared to webs built without space constraints. However, when space is limited, spiders can achieve higher net prey gain compared to building typical circular webs in the same limited space. Our model shows how spiders optimise web investment in sub-optimal conditions and can be used to understand foraging investment trade-offs in other central-place foragers faced with constrained foraging arenas.

  10. Universality classes of foraging with resource renewal.

    PubMed

    Chupeau, M; Bénichou, O; Redner, S

    2016-03-01

    We determine the impact of resource renewal on the lifetime of a forager that depletes its environment and starves if it wanders too long without eating. In the framework of a minimal starving random-walk model with resource renewal, there are three universal classes of behavior as a function of the renewal time. For sufficiently rapid renewal, foragers are immortal, while foragers have a finite lifetime otherwise. In the specific case of one dimension, there is a third regime, for sufficiently slow renewal, in which the lifetime of the forager is independent of the renewal time. We outline an enumeration method to determine the mean lifetime of the forager in the mortal regime.

  11. Foraging in groups affects giving-up densities: solo foragers quit sooner.

    PubMed

    Carthey, Alexandra J R; Banks, Peter B

    2015-07-01

    The giving-up density framework is an elegant and widely adopted mathematical approach to measuring animals' foraging decisions at non-replenishing artificial resource patches. Under this framework, an animal should "give up" when the benefits of foraging are outweighed by the costs (e.g., predation risk, energetic, and/or missed opportunity costs). However, animals of many species may forage in groups, and group size is expected to alter perceived predation risk and hence influence quitting decisions. Yet, most giving-up density studies assume either that individuals forage alone or that giving-up densities are not affected by group foraging. For animals that forage both alone and in groups, differences in giving-up densities due to group foraging rather than experimental variables may substantially alter interpretation. However, no research to date has directly investigated how group foraging affects the giving-up density. We used remote-sensing cameras to identify instances of group foraging in two species of Rattus across three giving-up density experiments to determine whether group foraging influences giving-up densities. Both Rattus species have been observed to vary between foraging alone and in groups. In all three experiments, solo foragers left higher giving-up densities on average than did group foragers. This result has important implications for studies using giving-up densities to investigate perceived risk, the energetic costs of searching, handling time, digestion, and missed opportunity costs, particularly if groups of animals are more likely to experience certain experimental treatments. It is critically important that future giving-up density studies consider the effects of group foraging.

  12. Eighteenth annual offshore technology conference. Volume 1

    SciTech Connect

    Not Available

    1986-01-01

    These sixty papers were given at a conference on offshore technology. Topics covered include friction effects of driving piles into sea beds of various compositions, wave forces on offshore platforms, stability, materials testing of various components such as plates, legs, wellheads, pipe joints, and protection of offshore platforms against ice and collision with icebergs.

  13. Foraging in an oxidative environment: relationship between δ13C values and oxidative status in Adélie penguins

    PubMed Central

    Beaulieu, Michaël; Ropert-Coudert, Yan; Le Maho, Yvon; Ancel, André; Criscuolo, François

    2010-01-01

    The alternation of short/coastal and long/pelagic foraging trips has been proposed as a strategy for seabirds to reconcile self-feeding and parental care. Both types of foraging trips may result in different foraging efforts and diet qualities, and consequently are likely to modify the oxidative status of seabirds. We examined the relationship between the oxidative status of Adélie penguins and (i) the duration of their foraging trips and (ii) their plasma δ13C values reflecting their spatial distribution. The oxidative status did not correlate with the foraging trip duration but with the δ13C values: high values being associated with high levels of oxidative damage. This relationship is likely to be related to the prey properties of penguins as both parameters are largely determined by the diet. Two non-exclusive hypotheses can be proposed to explain this relationship: (i) penguins foraging in coastal areas feed on a diet enriched in 13C and depleted in antioxidant compounds; (ii) birds with low antioxidant capacity are constrained to forage in coastal areas. Our study is the first to show that the adoption of different foraging strategies is associated with different levels of oxidative stress. However, further studies are needed to investigate the underlying mechanisms of this intriguing relationship. PMID:19955151

  14. After the frass: foraging pikas select patches previously grazed by caterpillars

    PubMed Central

    Barrio, Isabel C.; Hik, David S.; Peck, Kristen; Bueno, C. Guillermo

    2013-01-01

    Interactions among herbivores can shape the structure of their communities and drive their dynamics. However, detecting herbivore interactions can be challenging when they are deferred in space or time. Moreover, interactions among distantly related groups of herbivores, such as vertebrates and invertebrates, are poorly understood. We investigated the effect of invertebrate herbivory on the subsequent foraging choices of a small alpine-dwelling vertebrate, the collared pika (Ochotona collaris). We carried out a field experiment within pika territories, by presenting them with a choice of foraging sites following manipulation of invertebrate (caterpillar) herbivory. Pikas actively selected areas with increased, recent invertebrate herbivory. While the underlying mechanisms behind this interaction remain unknown, our results demonstrate a positive effect of invertebrate herbivores on subsequent vertebrate foraging preferences for the first time. Even among distantly related taxa, such interactions where one herbivore is cueing on the foraging of another, could drive the creation of herbivory hotspots, with cascading consequences for ecosystem processes. PMID:23616644

  15. After the frass: foraging pikas select patches previously grazed by caterpillars.

    PubMed

    Barrio, Isabel C; Hik, David S; Peck, Kristen; Bueno, C Guillermo

    2013-06-23

    Interactions among herbivores can shape the structure of their communities and drive their dynamics. However, detecting herbivore interactions can be challenging when they are deferred in space or time. Moreover, interactions among distantly related groups of herbivores, such as vertebrates and invertebrates, are poorly understood. We investigated the effect of invertebrate herbivory on the subsequent foraging choices of a small alpine-dwelling vertebrate, the collared pika (Ochotona collaris). We carried out a field experiment within pika territories, by presenting them with a choice of foraging sites following manipulation of invertebrate (caterpillar) herbivory. Pikas actively selected areas with increased, recent invertebrate herbivory. While the underlying mechanisms behind this interaction remain unknown, our results demonstrate a positive effect of invertebrate herbivores on subsequent vertebrate foraging preferences for the first time. Even among distantly related taxa, such interactions where one herbivore is cueing on the foraging of another, could drive the creation of herbivory hotspots, with cascading consequences for ecosystem processes.

  16. Patches of bare ground as a staple commodity for declining ground-foraging insectivorous farmland birds.

    PubMed

    Schaub, Michael; Martinez, Nicolas; Tagmann-Ioset, Aline; Weisshaupt, Nadja; Maurer, Melanie L; Reichlin, Thomas S; Abadi, Fitsum; Zbinden, Niklaus; Jenni, Lukas; Arlettaz, Raphaël

    2010-10-06

    Conceived to combat widescale biodiversity erosion in farmland, agri-environment schemes have largely failed to deliver their promises despite massive financial support. While several common species have shown to react positively to existing measures, rare species have continued to decline in most European countries. Of particular concern is the status of insectivorous farmland birds that forage on the ground. We modelled the foraging habitat preferences of four declining insectivorous bird species (hoopoe, wryneck, woodlark, common redstart) inhabiting fruit tree plantations, orchards and vineyards. All species preferred foraging in habitat mosaics consisting of patches of grass and bare ground, with an optimal, species-specific bare ground coverage of 30-70% at the foraging patch scale. In the study areas, birds thrived in intensively cultivated farmland where such ground vegetation mosaics existed. Not promoted by conventional agri-environment schemes until now, patches of bare ground should be implemented throughout grassland in order to prevent further decline of insectivorous farmland birds.

  17. Successful foraging zones of southern elephant seals from the Kerguelen Islands in relation to oceanographic conditions.

    PubMed

    Bailleul, Frédéric; Charrassin, Jean-Benoît; Monestiez, Pascal; Roquet, Fabien; Biuw, Martin; Guinet, Christophe

    2007-11-29

    Southern elephant seals, Mirounga leonina, undertake large-scale oceanic movements to access favourable foraging areas. Successful foraging areas of elephant seals from the Kerguelen Islands are investigated here in relation to oceanographic parameters. Movements and diving activity of the seals as well as oceanographic data were collected through a new generation of satellite relayed devices measuring and transmitting locations, pressure, temperature and salinity. For the first time, we have associated foraging behaviour, determined by high increased sinuosity in tracks, and dive density (i.e. number of dives performed per kilometre covered), and changes in body condition, determined by variations in drift rate obtained from drift dives, to identify the oceanographic conditions of successful foraging zones for this species. Two main sectors, one close to the Antarctic continent and the other along the Polar Front (PF), where both foraging activity and body condition increase, seem to be of particular interest for the seals. Within these regions, some seals tended to focus their foraging activity on zones with particular temperature signatures. Along the Antarctic continent, some seals targeted colder waters on the sea bottom during benthic dives, while at the PF the favourable zones tended to be warmer. The possible negative effect of colder waters in Antarctic on the swimming performances of potential fish or squid prey could explain the behaviour of elephant seals in these zones, while warmer waters within the PF could correspond to the optimal conditions for potential myctophid prey of elephant seals.

  18. Dynamics of intertidal foraging by coastal brown bears in Southwestern Alaska

    USGS Publications Warehouse

    Smith, T.S.; Partridge, Steven T.

    2004-01-01

    Shoreline areas provide early season foraging opportunities for coastal bears in Alaska. We investigated use by brown bears (Ursus arctos) of soft-shelled (Mya arenaria) and Pacific razor (Siliqua patula) clams at Katmai National Park, Alaska, USA, to identify the potential importance of these clams to bears. We used direct observations of bear foraging behavior in the summers of 1998, 1999, and 2001 to model the nutritional importance of clamming behavior. We also used previously described models to estimate the relative importance of clamming and vegetative foraging in meeting the maintenance requirements of bears. At the harvest rate that we observed (0.69 ?? 0.46 clams/min), bears achieved higher rates of digestible energy intake than those foraging on vegetation. Although clams are available for only a few hours per day, bears could significantly reduce their total daily foraging time by utilizing clams. Smaller single bears and females with dependent young were the most represented groups of bears using intertidal areas. Large male bears, faced with higher energy requirements, likely are unable to efficiently exploit these intertidal resources. Depending on the relationship between clam size and tissue mass, the relative quality of clams differed by species. Bears foraging on Pacific razor clams required the fewest hours to meet maintenance, followed by bears consuming soft-shelled clams. Our findings highlight the significance of intertidal habitats for coastal bears, especially females.

  19. Modeling Nonresident Seabird Foraging Distributions to Inform Ocean Zoning in Central California

    PubMed Central

    Hines, Ellen; Elliott, Meredith L.; Howar, Julie; Holzman, Barbara; Nur, Nadav; Jahncke, Jaime

    2017-01-01

    Seabird aggregations at sea have been shown to be associated with concentrations of prey. Previous research identified Central California as a highly used foraging area for seabirds, with locally breeding seabirds foraging close to their colonies on Southeast Farallon Island. Herein, we focus on nonresident (i.e. non-locally breeding) seabird species off of Central California. We hypothesized that high-use foraging areas for nonresident seabirds would be influenced by oceanographic and bathymetric factors and that spatial and temporal distributions would be similar within planktivorous and generalist foraging guilds but would differ between them. With data collected by the Applied California Current Ecosystem Studies (ACCESS) partnership during cruises between April and October from 2004–2013, we developed generalized linear models to identify high-use foraging areas for each of six nonresident seabird species. The four generalist species are Phoebastria nigripes (black-footed albatross), Ardenna griseus (sooty shearwater), Ardenna creatopus (pink-footed shearwater), and Fulmarus glacialis (northern fulmar). The two planktivorous species are Phalaropus lobatus (red-necked phalarope) and Phalaropus fulicarius (red phalarope). Sea surface temperature was significant for generalist species and sea surface salinity was important for planktivorous species. The distance to the 200-m isobath was significant in five of six models, Pacific Decadal Oscillation with a 3-month lag in four models, and sea surface fluorescence, the distance to Cordell Bank, and depth in three models. We did not find statistically significant differences between distributions of individual seabird species within a foraging guild or between guilds, with the exception of the sooty shearwater. Model results for a multi-use seabird foraging area highlighted the continental shelf break, particularly within the vicinity of Cordell Bank, as the highest use areas as did Marxan prioritization. Our

  20. Modeling Nonresident Seabird Foraging Distributions to Inform Ocean Zoning in Central California.

    PubMed

    Studwell, Anna J; Hines, Ellen; Elliott, Meredith L; Howar, Julie; Holzman, Barbara; Nur, Nadav; Jahncke, Jaime

    2017-01-01

    Seabird aggregations at sea have been shown to be associated with concentrations of prey. Previous research identified Central California as a highly used foraging area for seabirds, with locally breeding seabirds foraging close to their colonies on Southeast Farallon Island. Herein, we focus on nonresident (i.e. non-locally breeding) seabird species off of Central California. We hypothesized that high-use foraging areas for nonresident seabirds would be influenced by oceanographic and bathymetric factors and that spatial and temporal distributions would be similar within planktivorous and generalist foraging guilds but would differ between them. With data collected by the Applied California Current Ecosystem Studies (ACCESS) partnership during cruises between April and October from 2004-2013, we developed generalized linear models to identify high-use foraging areas for each of six nonresident seabird species. The four generalist species are Phoebastria nigripes (black-footed albatross), Ardenna griseus (sooty shearwater), Ardenna creatopus (pink-footed shearwater), and Fulmarus glacialis (northern fulmar). The two planktivorous species are Phalaropus lobatus (red-necked phalarope) and Phalaropus fulicarius (red phalarope). Sea surface temperature was significant for generalist species and sea surface salinity was important for planktivorous species. The distance to the 200-m isobath was significant in five of six models, Pacific Decadal Oscillation with a 3-month lag in four models, and sea surface fluorescence, the distance to Cordell Bank, and depth in three models. We did not find statistically significant differences between distributions of individual seabird species within a foraging guild or between guilds, with the exception of the sooty shearwater. Model results for a multi-use seabird foraging area highlighted the continental shelf break, particularly within the vicinity of Cordell Bank, as the highest use areas as did Marxan prioritization. Our

  1. Has eutrophication promoted forage fish production in the Baltic Sea?

    PubMed

    Eero, Margit; Andersson, Helén C; Almroth-Rosell, Elin; MacKenzie, Brian R

    2016-10-01

    Reducing anthropogenic nutrient inputs is a major policy goal for restoring good environmental status of coastal marine ecosystems. However, it is unclear to what extent reducing nutrients would also lower fish production and fisheries yields. Empirical examples of changes in nutrient loads and concurrent fish production can provide useful insights to this question. In this paper, we investigate to what extent a multi-fold increase in nutrient loads from the 1950s to 1980s enhanced forage fish production in the Baltic Sea. We use monitoring data on fish stock dynamics covering the period of the nutrient increase, combined with nutrient concentrations from a 3-dimensional coupled physical-biogeochemical ocean model. The results suggest that nutrient enrichment enhanced the biomass level of forage fish by up to 50 % in some years and areas due to increased body weight of fish. However, the trends in fish biomasses were generally decoupled from changes in nutrient concentrations.

  2. Protecting rain forests and forager's rights using LANDSAT imagery

    NASA Technical Reports Server (NTRS)

    Wilkie, David S.

    1991-01-01

    Creating rain forest reserves is vital given the global decline in biodiversity. Yet, the plants and animals that will be protected from untrammeled commercial exploitation within such reserves constitute essential resources for indigenous foragers and farmers. Balancing the needs of local subsistence level populations with the goals of national and international conservation agencies requires a thorough understanding of the mutual impacts that arise from the interaction of park and people. In the Ituri forest of Zaire, LANDSAT TM image analysis and GPS ground truth data were used to locate human settlements so that boundaries of the proposed Okapi Reserve could be chosen to minimize its impact on the subsistence practices of the local foragers and farmers. Using satellite imagery in conjunction with cultural information should help to ensure traditional resource exploitation rights of indigenous peoples whilst simultaneously protecting the largest contiguous area of undisturbed forest.

  3. Physical barrier to reduce WP mortalities of foraging waterfowl

    SciTech Connect

    Pochop, P.A.; Cummings, J.L.; Yoder, C.A.; Gossweiler, W.A.

    2000-02-01

    White phosphorus (WP) has been identified as the cause of mortality to certain species of water-fowl at Eagle River Flats, a tidal marsh in Alaska, used as an ordinance impact area by the US Army. A blend of calcium bentonite/organo clays, gravel, and binding polymers was tested for effectiveness as a barrier to reduce duck foraging and mortality. Following the application of the barrier to one of two contaminated ponds, the authors observed greater duck foraging and higher mortality in the untreated pond and no mortality in the treated pond after a year of tidal inundations and ice effects. Emergent vegetation recovered within a year of treatment. WP levels in the barrier were less than the method limit of detection, indicating no migration of WP into the materials. Barrier thickness remained relatively stable over a period of 4 years, and vegetation was found to be important in stabilizing the barrier material.

  4. Foundations for offshore wind turbines.

    PubMed

    Byrne, B W; Houlsby, G T

    2003-12-15

    An important engineering challenge of today, and a vital one for the future, is to develop and harvest alternative sources of energy. This is a firm priority in the UK, with the government setting a target of 10% of electricity from renewable sources by 2010. A component central to this commitment will be to harvest electrical power from the vast energy reserves offshore, through wind turbines or current or wave power generators. The most mature of these technologies is that of wind, as much technology transfer can be gained from onshore experience. Onshore wind farms, although supplying 'green energy', tend to provoke some objections on aesthetic grounds. These objections can be countered by locating the turbines offshore, where it will also be possible to install larger capacity turbines, thus maximizing the potential of each wind farm location. This paper explores some civil-engineering problems encountered for offshore wind turbines. A critical component is the connection of the structure to the ground, and in particular how the load applied to the structure is transferred safely to the surrounding soil. We review previous work on the design of offshore foundations, and then present some simple design calculations for sizing foundations and structures appropriate to the wind-turbine problem. We examine the deficiencies in the current design approaches, and the research currently under way to overcome these deficiencies. Designs must be improved so that these alternative energy sources can compete economically with traditional energy suppliers.

  5. China offshore has top priority

    SciTech Connect

    Cornitius, T.A.

    1983-11-01

    Joint venture development of offshore petroleum reserves has top priority in the mammoth effort to modernize the People's Republic of China. While the country works to overcome a critical shortage of skilled personnel, export of oil, coal, consumer goods, and metals will finance technological imports.

  6. Geological characterization of selected offshore sand resources on the OCS, offshore Alabama, for beach nourishment

    USGS Publications Warehouse

    Davies, David J.; Parker, Steven J.; Smith, W. Everett

    1993-01-01

    Most Alabama Gulf and estuarine shoreline is undergoing long-term erosion; threatened shorelines will need programs of replenishment and maintenance if they are to be even temporarily stabilized. Highest priority beach replenishment areas include eastern Dauphin Island; west of Perdido Pass; and west of the inlet at Little Lagoon. There are no appropriate local onshore sand sources available for any such large scale program. Sediments in the Federal waters of the EEZ were evaluated for possible sources of sand for beach nourishment. Six lithofacies were delineated based on sediment characterization, spatial framework, and environment of deposition; of these, two (Clean Sands and Graded Shelly Sands) were deemed to have highest potential as beach nourishment sources. Five offshore target areas were delineated as potential sand sources. Criteria included sand aesthetics, estimated sand volume, and sand distributions. Preliminary environmental analyses included impacts of offshore sand dredging on shelf circulation; on economic activities; and on local benthic biota. Dredging may not significantly alter background wave regimes; however, data are insufficient to model effects of major storms on a modified shelf morphology. Dredging would avoid areas of current economic activity. There would like be little long-term impact on benthic biota in the target areas. Additional work will be required to confirm or refute these preliminary findings.

  7. Sexual segregation in foraging giraffe

    NASA Astrophysics Data System (ADS)

    Mramba, Rosemary Peter; Mahenya, Obeid; Siyaya, Annetjie; Mathisen, Karen Marie; Andreassen, Harry Peter; Skarpe, Christina

    2017-02-01

    Sexual segregation in giraffe is known to vary between savannas. In this study, we compared sexual segregation in giraffe in one nutrient-rich savanna, the Serengeti National Park, one nutrient-poor, Mikumi National Park, and one medium rich savanna, Arusha National Park, (from here on referred to just by name) based on effects of sexual size dimorphism and related hypotheses. Data were collected in the wet and dry seasons, by driving road transects and making visual observations of browsing giraffe. Additional data were collected from literature (plant chemistry; mammal communities). There was a noticeable difference in browsing by females and males and in browsing between the three savannas. Females browsed a higher diversity of tree species in Serengeti whereas males browsed a higher diversity in Arusha, while the diversity of species browsed in Mikumi was high and about the same in both sexes. Females selected for high concentrations of nitrogen and low concentrations of tannins and phenolics compared to males in Serengeti but selection in Mikumi was more complex. Males browsed higher in the canopy than females in all sites, but the browsing height was generally higher in Serengeti than Mikumi and Arusha. Season had an effect on the browsing height independent of sex in Mikumi, where giraffes browsed higher in the dry season compared to the wet season. Males spent more time browsing per tree compared to females in all three sites; however, browsing time in Mikumi was also affected by season, where giraffes had longer browsing bouts in the wet season compared to the dry season. We suggest that sexual differences in forage requirement and in foraging interacts with differences in tree chemistry and in competing herbivore communities between nutrient rich and nutrient poor savanna in shaping the sexual segregation.

  8. Same size--same niche? Foraging niche separation between sympatric juvenile Galapagos sea lions and adult Galapagos fur seals.

    PubMed

    Jeglinski, Jana W E; Goetz, Kimberley T; Werner, Christiane; Costa, Daniel P; Trillmich, Fritz

    2013-05-01

    1. In vertebrates, patterns of resource utilization change throughout development according to age- and or size-specific abilities and requirements. Thus, interspecific competition affects different age classes differently. 2. Adults of sympatric species often show distinct foraging niche segregation, but juvenile resource use might overlap with adult competitors of similar body size. Resultant negative effects on juveniles can have important consequences for population dynamics, yet such interactions have received little attention in studies of mammalian communities. 3. Using GPS tracking devices, time-depth recorders and stable isotope data, we compared diving depth, activity time, trophic position and foraging habitat characteristics to investigate foraging niche overlap between similar-sized sympatric juvenile Galapagos sea lions (Zalophus wollebaeki) and adult Galapagos fur seals (Arctocephalus galapagoensis) and compared each group with much larger-bodied adult Galapagos sea lions. 4. We found little indication for direct competition but a complex pattern of foraging niche segregation: juvenile sea lions and adult fur seals dived to shallow depths at night, but foraged in different habitats with limited spatial overlap. Conversely, juvenile and adult sea lions employed different foraging patterns, but their foraging areas overlapped almost completely. 5. Consistency of foraging habitat characteristics between juvenile and adult sea lions suggests that avoidance of competition may be important in shaping foraging habitat utilization. Resultant specialization on a limited habitat could contribute to low sea lion numbers that contrast with high fur seal abundance. Our data suggest that exploitation by multiple predators within spatially restricted foraging ranges of juveniles might negatively impact juvenile foraging success and ultimately influence population dynamics.

  9. Perennial Forages as Second Generation Bioenergy Crops

    PubMed Central

    Sanderson, Matt A.; Adler, Paul R.

    2008-01-01

    The lignocellulose in forage crops represents a second generation of biomass feedstock for conversion into energy-related end products. Some of the most extensively studied species for cellulosic feedstock production include forages such as switchgrass (Panicum virgatum L.), reed canarygrass (Phalaris arundinacea L.), and alfalfa (Medicago sativa L.). An advantage of using forages as bioenergy crops is that farmers are familiar with their management and already have the capacity to grow, harvest, store, and transport them. Forage crops offer additional flexibility in management because they can be used for biomass or forage and the land can be returned to other uses or put into crop rotation. Estimates indicate about 22.3 million ha of cropland, idle cropland, and cropland pasture will be needed for biomass production in 2030. Converting these lands to large scale cellulosic energy farming could push the traditional forage-livestock industry to ever more marginal lands. Furthermore, encouraging bioenergy production from marginal lands could directly compete with forage-livestock production. PMID:19325783

  10. Optimization of monopiles for offshore wind turbines.

    PubMed

    Kallehave, Dan; Byrne, Byron W; LeBlanc Thilsted, Christian; Mikkelsen, Kristian Kousgaard

    2015-02-28

    The offshore wind industry currently relies on subsidy schemes to be competitive with fossil-fuel-based energy sources. For the wind industry to survive, it is vital that costs are significantly reduced for future projects. This can be partly achieved by introducing new technologies and partly through optimization of existing technologies and design methods. One of the areas where costs can be reduced is in the support structure, where better designs, cheaper fabrication and quicker installation might all be possible. The prevailing support structure design is the monopile structure, where the simple design is well suited to mass-fabrication, and the installation approach, based on conventional impact driving, is relatively low-risk and robust for most soil conditions. The range of application of the monopile for future wind farms can be extended by using more accurate engineering design methods, specifically tailored to offshore wind industry design. This paper describes how state-of-the-art optimization approaches are applied to the design of current wind farms and monopile support structures and identifies the main drivers where more accurate engineering methods could impact on a next generation of highly optimized monopiles.

  11. National Offshore Wind Energy Grid Interconnection Study

    SciTech Connect

    Daniel, John P.; Liu, Shu; Ibanez, Eduardo; Pennock, Ken; Reed, Greg; Hanes, Spencer

    2014-07-30

    The National Offshore Wind Energy Grid Interconnection Study (NOWEGIS) considers the availability and potential impacts of interconnecting large amounts of offshore wind energy into the transmission system of the lower 48 contiguous United States. A total of 54GW of offshore wind was assumed to be the target for the analyses conducted. A variety of issues are considered including: the anticipated staging of offshore wind; the offshore wind resource availability; offshore wind energy power production profiles; offshore wind variability; present and potential technologies for collection and delivery of offshore wind energy to the onshore grid; potential impacts to existing utility systems most likely to receive large amounts of offshore wind; and regulatory influences on offshore wind development. The technologies considered the reliability of various high-voltage ac (HVAC) and high-voltage dc (HVDC) technology options and configurations. The utility system impacts of GW-scale integration of offshore wind are considered from an operational steady-state perspective and from a regional and national production cost perspective.

  12. Return Customers: Foraging Site Fidelity and the Effect of Environmental Variability in Wide-Ranging Antarctic Fur Seals

    PubMed Central

    Arthur, Benjamin; Hindell, Mark; Bester, Marthan; Trathan, Phil; Jonsen, Ian; Staniland, Iain; Oosthuizen, W. Chris; Wege, Mia; Lea, Mary-Anne

    2015-01-01

    Strategies employed by wide-ranging foraging animals involve consideration of habitat quality and predictability and should maximise net energy gain. Fidelity to foraging sites is common in areas of high resource availability or where predictable changes in resource availability occur. However, if resource availability is heterogeneous or unpredictable, as it often is in marine environments, then habitat familiarity may also present ecological benefits to individuals. We examined the winter foraging distribution of female Antarctic fur seals, Arctocephalus gazelle, over four years to assess the degree of foraging site fidelity at two scales; within and between years. On average, between-year fidelity was strong, with most individuals utilising more than half of their annual foraging home range over multiple years. However, fidelity was a bimodal strategy among individuals, with five out of eight animals recording between-year overlap values of greater than 50%, while three animals recorded values of less than 5%. High long-term variance in sea surface temperature, a potential proxy for elevated long-term productivity and prey availability, typified areas of overlap. Within-year foraging site fidelity was weak, indicating that successive trips over the winter target different geographic areas. We suggest that over a season, changes in prey availability are predictable enough for individuals to shift foraging area in response, with limited associated energetic costs. Conversely, over multiple years, the availability of prey resources is less spatially and temporally predictable, increasing the potential costs of shifting foraging area and favouring long-term site fidelity. In a dynamic and patchy environment, multi-year foraging site fidelity may confer a long-term energetic advantage to the individual. Such behaviours that operate at the individual level have evolutionary and ecological implications and are potential drivers of niche specialization and modifiers of

  13. Return customers: foraging site fidelity and the effect of environmental variability in wide-ranging antarctic fur seals.

    PubMed

    Arthur, Benjamin; Hindell, Mark; Bester, Marthan; Trathan, Phil; Jonsen, Ian; Staniland, Iain; Oosthuizen, W Chris; Wege, Mia; Lea, Mary-Anne

    2015-01-01

    Strategies employed by wide-ranging foraging animals involve consideration of habitat quality and predictability and should maximise net energy gain. Fidelity to foraging sites is common in areas of high resource availability or where predictable changes in resource availability occur. However, if resource availability is heterogeneous or unpredictable, as it often is in marine environments, then habitat familiarity may also present ecological benefits to individuals. We examined the winter foraging distribution of female Antarctic fur seals, Arctocephalus gazelle, over four years to assess the degree of foraging site fidelity at two scales; within and between years. On average, between-year fidelity was strong, with most individuals utilising more than half of their annual foraging home range over multiple years. However, fidelity was a bimodal strategy among individuals, with five out of eight animals recording between-year overlap values of greater than 50%, while three animals recorded values of less than 5%. High long-term variance in sea surface temperature, a potential proxy for elevated long-term productivity and prey availability, typified areas of overlap. Within-year foraging site fidelity was weak, indicating that successive trips over the winter target different geographic areas. We suggest that over a season, changes in prey availability are predictable enough for individuals to shift foraging area in response, with limited associated energetic costs. Conversely, over multiple years, the availability of prey resources is less spatially and temporally predictable, increasing the potential costs of shifting foraging area and favouring long-term site fidelity. In a dynamic and patchy environment, multi-year foraging site fidelity may confer a long-term energetic advantage to the individual. Such behaviours that operate at the individual level have evolutionary and ecological implications and are potential drivers of niche specialization and modifiers of

  14. Sex-specific foraging behaviour in a seabird with reversed sexual dimorphism: the red-footed booby.

    PubMed

    Weimerskirch, Henri; Le Corre, Matthieu; Ropert-Coudert, Yan; Kato, Akiko; Marsac, Francis

    2006-01-01

    Most hypotheses attempting to explain the evolution of reversed sexual dimorphism (RSD) assume that size-related differences in foraging ability are of prime importance, but the studies on sex-specific differences in foraging behaviour remain scarce. We compare the foraging behaviour of males and females in a seabird species with a RSD by using several miniaturised activity and telemetry loggers. In red-footed boobies males are 5% smaller and 15% lighter than females, but have a longer tail than females. Both sexes spend similar time on the nest while incubating or brooding. When foraging at sea, males and females spend similar time foraging in oceanic waters, forage in similar areas, spend similar proportion of their foraging trip in flight, and feed on similar prey-flying fishes and flying squids-of similar size. However, compared to males, females range farther during incubation (85 km vs. 50 km), and furthermore feed mostly at the extremity of their foraging trip, whereas males actively forage throughout the trip. Males are much more active than females, landing and diving more often. During the study period, males lost mass, whereas females showed no significant changes. These results indicate that males and females of the red-footed boobies differ in several aspects in their foraging behaviour. Although some differences found in the study may be the direct result of the larger size of females, that is, the slightly higher speeds and deeper depths attained by females, others indicate clearly different foraging strategies between the sexes. The smaller size and longer tail of males confer them a higher agility, and could allow them to occupy a foraging niche different from that of females. The higher foraging effort of males related to its different foraging strategy is probably at the origin of the rapid mass loss of males during the breeding period. These results suggest that foraging differences are probably the reason for the differential breeding

  15. Ungulate exclusion, conifer thinning and mule deer forage in northeastern New Mexico

    USGS Publications Warehouse

    Kramer, David W.; Sorensen, Grant E.; Taylor, Chase A.; Cox, Robert D.; Gipson, Philip S.; Cain, James W.

    2015-01-01

    The southwestern United States has experienced expansion of conifer species (Juniperus spp. and Pinus ponderosa) into areas of semi-arid grassland over the past century. The expansion of conifers can limit palatable forage and reduce grass and forb communities. Conifer species are sometimes thinned through hydraulic mulching or selective cutting. We assessed the effects of these treatments on mule deer (Odocoileus hemionus) habitat in northeastern New Mexico to determine if conifer thinning improved cover of preferred forage species for mule deer in areas with and without ungulates. We measured plant cover and occurrence of preferred forage species in the summers of 2011 and 2012. An ongoing regional drought probably reduced vegetation response, with preferred forage species and herbaceous cover responding to conifer thinning or ungulate exclusion immediately following treatment, but not the following year. In 2011, areas that received thinning treatments had a higher abundance of preferred forage when compared to sites with no treatment. Grass coverage exhibited an immediate response in 2011, with ungulate exclosures containing 8% more coverage than areas without exclosures. The results suggest that conifer thinning and ungulate exclusion may elicit a positive response, however in the presence of drought; the positive effects are only short-term.

  16. QTL mapping of forage yield and forage yield component traits in Sorghum bicolor x S. sudanense.

    PubMed

    Liu, Y L; Wang, L H; Li, J Q; Zhan, Q W; Zhang, Q; Li, J F; Fan, F F

    2015-04-22

    The sorghum-sudangrass hybrid (Sorghum bicolor x S. sudanense) is an important forage crop. However, little is known about the genetic mechanisms related to forage yield and the 4 forage yield component traits in this forage crop. In this study, a linkage map was constructed with 124 assigned SSR markers using an F2 mapping population derived from the crossing of sorghum Tx623A and sudangrass Sa. Nine quantitative trait loci (QTLs) were detected for forage yield and the 4 forage yield component traits using inclusive composite interval mapping. Five fresh weight QTLs were identified and contributed >50% of the total phenotypic variance. Of these QTLs, all showed additive and dominant effects, but most exhibited mainly dominant effects. These results will provide useful information for improvements in sorghum-sudangrass hybrid breeding.

  17. Optimal Foraging by Birds: Experiments for Secondary & Postsecondary Students

    ERIC Educational Resources Information Center

    Pecor, Keith W.; Lake, Ellen C.; Wund, Matthew A.

    2015-01-01

    Optimal foraging theory attempts to explain the foraging patterns observed in animals, including their choice of particular food items and foraging locations. We describe three experiments designed to test hypotheses about food choice and foraging habitat preference using bird feeders. These experiments can be used alone or in combination and can…

  18. Differences in foraging activity of deep sea diving odontocetes in the Ligurian Sea as determined by passive acoustic recorders

    NASA Astrophysics Data System (ADS)

    Giorli, Giacomo; Au, Whitlow W. L.; Neuheimer, Anna

    2016-01-01

    Characterizing the trophic roles of deep-diving odontocete species and how they vary in space and time is challenged by our ability to observe foraging behavior. Though sampling methods are limited, foraging activity of deep-diving odontocetes can be monitored by recording their biosonar emissions. Daily occurrence of echolocation clicks was monitored acoustically for five months (July-December 2011) in the Ligurian Sea (Mediterranean Sea) using five passive acoustic recorders. Detected odontocetes included Cuvier's beaked whales (Zipuhius cavirostris), sperm whales (Physeter macrocephalus), Risso's dolphins (Grampus griseus), and long-finned pilot whales (Globicephala melas). The results indicated that the foraging strategies varied significantly over time, with sperm whales switching to nocturnal foraging in late September whereas Risso's dolphins and pilot whales foraged mainly at night throughout the sampling period. In the study area, winter nights are about five hours longer than summer nights and an analysis showed that pilot whales and Risso's dolphins adjusted their foraging activity with the length of the night, foraging longer during the longer winter nights. This is the first study to show that marine mammals exhibit diurnal foraging patterns closely correlated to sunrise and sunset.

  19. Operators renewing exploration in offshore basins of France

    SciTech Connect

    Lamiraux, C.; Mascle, A.

    1995-07-03

    Forty nine wells were drilled without success from the latter 1960s to the first half of the 1980s in French offshore areas. About 10 years of reduced activity followed this first phase of exploration. For a couple of years, these areas have been closely reassessed, taking into account the experience and data previously acquired. More particularly, a better understanding of tectonic processes at the origin of complex structural traps, a better taking into account of the distribution, quality, and maturation history of source rocks, together with significant improvements in seismic data acquisition-processing and basin modeling techniques, have led a few oil companies to apply for licenses in three offshore areas. The paper discusses prospects in the Bay of Biscay, the Iroise Sea and English Channel, and the Gulf of Lions.

  20. Foraging habitat for shorebirds in southeastern Missouri and its predicted future availability

    USGS Publications Warehouse

    Twedt, Daniel J.

    2013-01-01

    Water management to protect agriculture in alluvial floodplains often conflicts with wildlife use of seasonal floodwater. Such is the case along the Mississippi River in southeastern Missouri where migrating shorebirds forage in shallow-flooded fields. I estimated the current availability of habitat for foraging shorebirds within the New Madrid and St. Johns Basins based on daily river elevations (1943–2009), under assumptions that shorebirds forage in open habitat with water depth <15 cm and use mudflats for 3 days after exposure. The area of shorebird foraging habitat, based on replicated 50-year random samples, averaged 975 ha per day during spring and 33 ha per day during fall. Adjustments to account for habitat quality associated with different water depths, duration of mudflat exposure, intra-seasonal availability, and state of agricultural crops, indicated the equivalent of 494 ha daily of optimal habitat during spring and 11 ha during fall. Proposed levees and pumps to protect cropland would reduce shorebird foraging habitat by 80 %: to 211 ha (108 optimal ha) per day during spring and 9 ha (<3 optimal ha) per day during fall. Alternative water management that allows natural flooding below a prescribed elevation would retain nearly all existing shorebird foraging habitat during fall and about 60 % of extant habitat during spring.

  1. Climate-driven sympatry may not lead to foraging competition between congeneric top-predators

    PubMed Central

    Cimino, Megan A.; Moline, Mark A.; Fraser, William R.; Patterson-Fraser, Donna L.; Oliver, Matthew J.

    2016-01-01

    Climate-driven sympatry may lead to competition for food resources between species. Rapid warming in the West Antarctic Peninsula (WAP) is coincident with increasing gentoo penguin and decreasing Adélie penguin populations, suggesting that competition for food may exacerbate the Adélie penguin decline. On fine scales, we tested for foraging competition between these species during the chick-rearing period by comparing their foraging behaviors with the distribution of their prey, Antarctic krill. We detected krill aggregations within the horizontal and vertical foraging ranges of Adélie and gentoo penguins, and found that krill selected for habitats that balance the need to consume food and avoid predation. In overlapping Adélie and gentoo penguin foraging areas, four gentoo penguins switched foraging behavior by foraging at deeper depths, a strategy which limits competition with Adélie penguins. This suggests that climate-driven sympatry does not necessarily result in competitive exclusion of Adélie penguins by gentoo penguins. Contrary to a recent theory, which suggests that increased competition for krill is one of the major drivers of Adélie penguin population declines, we suggest that declines in Adélie penguins along the WAP are more likely due to direct and indirect climate impacts on their life histories. PMID:26732496

  2. Climate-driven sympatry may not lead to foraging competition between congeneric top-predators.

    PubMed

    Cimino, Megan A; Moline, Mark A; Fraser, William R; Patterson-Fraser, Donna L; Oliver, Matthew J

    2016-01-06

    Climate-driven sympatry may lead to competition for food resources between species. Rapid warming in the West Antarctic Peninsula (WAP) is coincident with increasing gentoo penguin and decreasing Adélie penguin populations, suggesting that competition for food may exacerbate the Adélie penguin decline. On fine scales, we tested for foraging competition between these species during the chick-rearing period by comparing their foraging behaviors with the distribution of their prey, Antarctic krill. We detected krill aggregations within the horizontal and vertical foraging ranges of Adélie and gentoo penguins, and found that krill selected for habitats that balance the need to consume food and avoid predation. In overlapping Adélie and gentoo penguin foraging areas, four gentoo penguins switched foraging behavior by foraging at deeper depths, a strategy which limits competition with Adélie penguins. This suggests that climate-driven sympatry does not necessarily result in competitive exclusion of Adélie penguins by gentoo penguins. Contrary to a recent theory, which suggests that increased competition for krill is one of the major drivers of Adélie penguin population declines, we suggest that declines in Adélie penguins along the WAP are more likely due to direct and indirect climate impacts on their life histories.

  3. Availability and toxicity of cadmium to forage grasses grown in contaminated soil.

    PubMed

    Silva, Enilson B; Fonseca, Felipe G; Alleoni, Luís R F; Nascimento, Sandra S; Grazziotti, Paulo H; Nardis, Bárbara O

    2016-09-01

    It is important to know the mechanisms for forage development, especially those related to the tolerance of potentially toxic elements, when considering their use in phytoremediation in heavy metal contaminated areas. In this study, we evaluated plant growth, concentration, and the availability of cadmium (Cd) for forage grasses (Panicum maximum Jacq. cv. Aruana and cv. Tanzânia; Brachiaria decumbens cv. Basilisk; Brachiaria brizantha cv. Xaraés and cv. Marandu) cultivated in Cd contaminated soils. The experiments were performed under greenhouse conditions over a 90-day evaluation period, and the Cd rates were 2, 4, and 12 mg/kg of soil. The relative growth rate of the forage grasses decreased as Cd rates increased, and the following descending order of susceptibility was observed: Marandu > Xaraés > Aruana > Tanzânia > Basilisk, with regard to phytotoxicity in these plants. The forage Cd concentration increased in line with increases in the Cd rates. Cd contents extracted by Mehlich-1 and by diethylenetriaminepentaacetic acid presented high positive correlation with forage relative growth. The forage plants did not block Cd entry into the food chain because they were not capable of limiting Cd absorption.

  4. Foraging and farming as niche construction: stable and unstable adaptations.

    PubMed

    Rowley-Conwy, Peter; Layton, Robert

    2011-03-27

    All forager (or hunter-gatherer) societies construct niches, many of them actively by the concentration of wild plants into useful stands, small-scale cultivation, burning of natural vegetation to encourage useful species, and various forms of hunting, collectively termed 'low-level food production'. Many such niches are stable and can continue indefinitely, because forager populations are usually stable. Some are unstable, but these usually transform into other foraging niches, not geographically expansive farming niches. The Epipalaeolithic (final hunter-gatherer) niche in the Near East was complex but stable, with a relatively high population density, until destabilized by an abrupt climatic change. The niche was unintentionally transformed into an agricultural one, due to chance genetic and behavioural attributes of some wild plant and animal species. The agricultural niche could be exported with modifications over much of the Old World. This was driven by massive population increase and had huge impacts on local people, animals and plants wherever the farming niche was carried. Farming niches in some areas may temporarily come close to stability, but the history of the last 11,000 years does not suggest that agriculture is an effective strategy for achieving demographic and political stability in the world's farming populations.

  5. Foraging and farming as niche construction: stable and unstable adaptations

    PubMed Central

    Rowley-Conwy, Peter; Layton, Robert

    2011-01-01

    All forager (or hunter–gatherer) societies construct niches, many of them actively by the concentration of wild plants into useful stands, small-scale cultivation, burning of natural vegetation to encourage useful species, and various forms of hunting, collectively termed ‘low-level food production’. Many such niches are stable and can continue indefinitely, because forager populations are usually stable. Some are unstable, but these usually transform into other foraging niches, not geographically expansive farming niches. The Epipalaeolithic (final hunter–gatherer) niche in the Near East was complex but stable, with a relatively high population density, until destabilized by an abrupt climatic change. The niche was unintentionally transformed into an agricultural one, due to chance genetic and behavioural attributes of some wild plant and animal species. The agricultural niche could be exported with modifications over much of the Old World. This was driven by massive population increase and had huge impacts on local people, animals and plants wherever the farming niche was carried. Farming niches in some areas may temporarily come close to stability, but the history of the last 11 000 years does not suggest that agriculture is an effective strategy for achieving demographic and political stability in the world's farming populations. PMID:21320899

  6. Migration, Foraging, and Residency Patterns for Northern Gulf Loggerheads: Implications of Local Threats and International Movements

    PubMed Central

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

    2014-01-01

    Northern Gulf of Mexico (NGoM) loggerheads (Caretta caretta) make up one of the smallest subpopulations of this threatened species and have declining nest numbers. We used satellite telemetry and a switching state-space model to identify distinct foraging areas used by 59 NGoM loggerheads tagged during 2010–2013. We tagged turtles after nesting at three sites, 1 in Alabama (Gulf Shores; n = 37) and 2 in Florida (St. Joseph Peninsula; n = 20 and Eglin Air Force Base; n = 2). Peak migration time was 22 July to 9 August during which >40% of turtles were in migration mode; the mean post-nesting migration period was 23.0 d (±13.8 d SD). After displacement from nesting beaches, 44 turtles traveled to foraging sites where they remained resident throughout tracking durations. Selected foraging locations were variable distances from tagging sites, and in 5 geographic regions; no turtles selected foraging sites outside the Gulf of Mexico (GoM). Foraging sites delineated using 50% kernel density estimation were located a mean distance of 47.6 km from land and in water with mean depth of −32.5 m; other foraging sites, delineated using minimum convex polygons, were located a mean distance of 43.0 km from land and in water with a mean depth of −24.9 m. Foraging sites overlapped with known trawling activities, oil and gas extraction activities, and the footprint of surface oiling during the 2010 Deepwater Horizon oil spill (n = 10). Our results highlight the year-round use of habitats in the GoM by loggerheads that nest in the NGoM. Our findings indicate that protection of females in this subpopulation requires both international collaborations and management of threats that spatially overlap with distinct foraging habitats. PMID:25076053

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

    USGS Publications Warehouse

    Hart, Kristen M.; Lamont, Margaret M.; Sartain-Iverson, Autumn R.; Fujisaki, Ikuko

    2014-01-01

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

  8. Foraging and nesting habitat of breeding male northern goshawks in the laurentian mixed forest province, Minnesota

    USGS Publications Warehouse

    Boal, C.W.; Andersen, D.E.; Kennedy, P.L.

    2005-01-01

    We used radiotelemetry to examine foraging habitat preferences of 17 breeding, male northern goshawks (Accipiter gentilis) in Minnesota from 1998-2000. We assessed habitat preference using radio relocation points and 50-m radius buffers of radio relocation points. Our data suggested that foraging male goshawks used early-successional upland conifer stands (???25 yrs old), early-successional upland deciduous stands (???50 yrs old), late-successional upland conifer stands (???50 yrs old), and late-successional upland deciduous stands (???50 yrs old) more frequently than expected based on the abundance of these vegetation types in the landscape. The 2 most available stand types, early-successional upland deciduous (<25 yrs old) and all ages of late-successional lowland conifer stands, were used less than expected by foraging goshawks. Late-successional lowland deciduous stands (???50 yrs old) were used in proportion to availability. Although analysis of relocation points suggested early-successional upland deciduous stands (25-49 yrs old) and late-successional upland conifer stands (???50 yrs old) were used in proportion to availability, analysis of buffers around relocation points indicated that these stand types were also used more than expected by foraging goshawks. Regardless of vegetation community type, stands used by goshawks were structurally similar with high canopy and understory stem densities, high canopy closure, substantial shrub cover, and large amounts of woody debris. Nest stands consisted of taller and larger diameter canopy trees and fewer understory trees than foraging stands, but stands were otherwise similar in structural features, suggesting goshawks used similar stands for nesting and foraging but that they tended to select the most mature stands for nesting. A commonality among nesting and foraging stands was the presence of open spaces between the canopy and understory foliage, and between understory and shrub layer foliage. In our study area

  9. Eddies as Offshore Foraging Grounds for Melon-Headed Whales (Peponocephala electra)

    DTIC Science & Technology

    2011-01-01

    production in the Sargasso Sea . Deep- Sea Research Part I 44:1427–1450. Patzert,W. C., andK.Wyrtki. 1974. Anticyclonic flow around theHawaiian Islands...in Smith and Sandwell (1997). Daily sea surface height (SSH) and currents with 0.08◦ resolution from the HYCOM Hawai‘i regional model were examined...are available daily and the latter only as weekly means (http:// www.aviso.oceanobs.com/en/data/products/ sea -surface- height-products/global

  10. Offshore drilling platform protection device

    SciTech Connect

    Magill, J.M.

    1981-12-15

    A description is given of an offshore drilling platform protection device for use on an offshore oil well drilling vessel including a drilling platform supportable on a plurality of extendable legs wherein each leg is moved by a rack gear assembly. The rack gear assembly includes an otherwise exposed first gear which engages a second gear positioned in a housing having a rectangular corner opening through which the first gear extends, the protection device including first and second protective sections adapted for mounting over the first gear adjacent to the rectangular corner of the housing for the second gear, the first and second protective sections cooperating to provide an l-shaped opening which communicates with the opening at the second gear housing for protecting the first gear while allowing the first gear to mesh with the second gear.

  11. 77 FR 47522 - Special Local Regulation; Port Huron Offshore Gran Prix, St. Clair River; Port Huron, MI

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-09

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation; Port Huron Offshore Gran Prix... prior to, during, and immediately after the Port Huron Offshore Gran Prix boat race. This special local..., the regulated navigation area is designed to minimize its impact on navigable waters. Furthermore,...

  12. Zebrafish learn to forage in the dark.

    PubMed

    Carrillo, Andres; McHenry, Matthew J

    2016-02-01

    A large diversity of fishes struggle early in life to forage on zooplankton while under the threat of predation. Some species, such as zebrafish (Danio rerio), acquire an ability to forage in the dark during growth as larvae, but it is unclear how this is achieved. We investigated the functional basis of this foraging by video-recording larval and juvenile zebrafish as they preyed on zooplankton (Artemia sp.) under infrared illumination. We found that foraging improved with age, to the extent that 1-month-old juveniles exhibited a capture rate that was an order of magnitude greater than that of hatchlings. At all ages, the ability to forage in the dark was diminished when we used a chemical treatment to compromise the cranial superficial neuromasts, which facilitate flow sensing. However, a morphological analysis showed no developmental changes in these receptors that could enhance sensitivity. We tested whether the improvement in foraging with age could instead be a consequence of learning by raising fish that were naïve to the flow of prey. After 1 month of growth, both groups foraged with a capture rate that was significantly less than that of fish that had the opportunity to learn and indistinguishable from that of fish with no ability to sense flow. This suggests that larval fish learn to use water flow to forage in the dark. This ability could enhance resource acquisition under reduced competition and predation. Furthermore, our findings offer an example of learning in a model system that offers promise for understanding its neurophysiological basis.

  13. Pipelaying in artic offshore waters

    SciTech Connect

    Langner, C. G.

    1985-11-19

    The present invention provides a method and apparatus for constructing pipelines in Arctic offshore waters by a directional drilling technique, thereby minimizing exposure to ice gouging and eliminating the hazards associated with unstable permafrost. A special drilling-pipe-line construction vessel is also provided which has a conical shape with reinforced outer walls to resist ice forces, which vessel includes means to install deep underground pipeline segments and means to connect and protect the pipe ends.

  14. Fatigue handbook: Offshore steel structures

    SciTech Connect

    Almarnaess, A.

    1985-01-01

    The contents of this book are: Overview of Offshore Steel Structures; Loads on Ocean Structures; Fracture Mechanics As a Tool in Fatigue Analysis; Basic Fatigue Properties of Welded Joints; Significance of Defects; Improving the Fatigue Strength of Welded Joints; Effects of Marine Environment and Cathodic Protection on Fatigue of Structural Steels Fatigue of Tubular Joints; Unstable Fracture; Fatigue Life Calculations; and Fatigue in Building Codes Background and Applications.

  15. Two offshore Australian crudes assayed

    SciTech Connect

    Rhodes, A.K.

    1994-05-09

    Two light, sweet crudes from offshore Australia have been assayed. Gippsland crude, also called Bass Strait, is produced off the coast of Victoria, in southeastern Australia. The 47 API, 0.09% sulfur crude was analyzed in mid-1993. Skua, a 42 API, 0.06 wt % sulfur crude, is produced in the Timor Sea. Data are given on the whole crude and fractions for both deposits. Both chemical and physical properties are listed.

  16. Offshore sand and gravel mining

    SciTech Connect

    Pandan, J.W.

    1983-05-01

    This paper reviews the status of mining offshore for sand and gravel on a world-wide basis. It discusses the technology for exploration and evaluation of sea floor mineral targets, as well as mining, transportation, and processing. Large operations in Japan and Europe are described, based upon personal observations of the author. The U.S. situation is outlined and opinions offered as to the outlook for the future.

  17. Foraging habitats of lactating northern fur seals are structured by thermocline depths and submesoscale fronts in the eastern Bering Sea

    NASA Astrophysics Data System (ADS)

    Nordstrom, Chad A.; Battaile, Brian C.; Cotté, Cédric; Trites, Andrew W.

    2013-04-01

    The relationships between fine-scale oceanographic features, prey aggregations, and the foraging behavior of top predators are poorly understood. We investigated whether foraging patterns of lactating northern fur seals (Callorhinus ursinus) from two breeding colonies located in different oceanographic domains of the eastern Bering Sea (St. Paul Island—shelf; Bogoslof Island—oceanic) were a function of submesoscale oceanographic features. We tested this by tracking 87 lactating fur seals instrumented with bio-logging tags (44 St. Paul Island, 43 Bogoslof Island) during July-September, 2009. We identified probable foraging hotspots using first-passage time analysis and statistically linked individual areas of high-use to fine-scale oceanographic features using mixed-effects Cox-proportional hazard models. We found no overlap in foraging areas used by fur seals from the two islands, but a difference in the duration of their foraging trips—trips from St. Paul Island were twice as long (7.9 d average) and covered 3-times the distance (600 km average) compared to trips from Bogoslof Island. St. Paul fur seals also foraged at twice the scale (mean radius=12 km) of Bogoslof fur seals (6 km), which suggests that prey were more diffuse near St. Paul Island than prey near Bogoslof Island. Comparing first passage times with oceanographic covariates revealed that foraging hotspots were linked to thermocline depth and occurred near submesoscale surface fronts (eddies and filaments). St. Paul fur seals that mixed epipelagic (night) and benthic (day) dives primarily foraged on-shelf in areas with deeper thermoclines that may have concentrated prey closer to the ocean floor, while strictly epipelagic (night) foragers tended to use waters with shallower thermoclines that may have aggregated prey closer to the surface. Fur seals from Bogoslof Island foraged almost exclusively over the Bering Sea basin and appeared to hunt intensively along submesoscale fronts that may have

  18. What can wave energy learn from offshore oil and gas?

    PubMed

    Jefferys, E R

    2012-01-28

    This title may appear rather presumptuous in the light of the progress made by the leading wave energy devices. However, there may still be some useful lessons to be learnt from current 'offshore' practice, and there are certainly some awful warnings from the past. Wave energy devices and the marine structures used in oil and gas exploration as well as production share a common environment and both are subject to wave, wind and current loads, which may be evaluated with well-validated, albeit imperfect, tools. Both types of structure can be designed, analysed and fabricated using similar tools and technologies. They fulfil very different missions and are subject to different economic and performance requirements; hence 'offshore' design tools must be used appropriately in wave energy project and system design, and 'offshore' cost data should be adapted for 'wave' applications. This article reviews the similarities and differences between the fields and highlights the differing economic environments; offshore structures are typically a small to moderate component of field development cost, while wave power devices will dominate overall system cost. The typical 'offshore' design process is summarized and issues such as reliability-based design and design of not normally manned structures are addressed. Lessons learned from poor design in the past are discussed to highlight areas where care is needed, and wave energy-specific design areas are reviewed. Opportunities for innovation and optimization in wave energy project and device design are discussed; wave energy projects must ultimately compete on a level playing field with other routes to low CO₂ energy and/or energy efficiency. This article is a personal viewpoint and not an expression of a ConocoPhillips position.

  19. Offshore structure and method of sinking same

    SciTech Connect

    Fern, D. T.

    1985-02-05

    An offshore structure and a method of skinking it to the sea bed. In accordance with one aspect of this invention, the structure is sunk asymmetrically by first sinking a first end portion thereof and then sinking the other end portion. The first end portion is sunk by ballasting it while the other end portion is closed to ballast. The structure is provided with sufficient water plane area while sinking each end portion to maintain stability during the sinking process. In accordance with another aspect of this invention, at least two spaced-apart piles are provided at the end corresponding to the first end portion to absorb the force of impact with the sea bed and to maintain a skirt on the structure out of contact with the sea bed until both ends of the structure have been sunk to the sea bed.

  20. Offshore oil: Correctness of perspective

    SciTech Connect

    Burns, R.F.

    1993-05-01

    Except for the Gulf of Mexico, the offshore oil industry has been virtually banned from the US Exclusive Economic Zone for ten years. The oil potential in Alaska's Arctic National Wildlife Refuge (ANWR) is also off limits. The Gulf of Mexico is the only place with prospects for future success and a number of companies both large and small are determined to move forward. The depressed price of oil does not encourage development but recently gas prices in the US have increased, making offshore gas development more feasible. Perhaps most significant is development and application of new technology and more intense management to make sure it works. The offshore oil companies and support industries have made significant technological advances, expending over and above the dollars paid in taxes, lease fees, and royalties. The ocean industries harbor a great reservoir of high technology knowledge. They have demonstrated the ability to successfully meet a vast array of challenges in exploring for, drilling, and producing oil and gas in extreme conditions. These facts beg the question as to the rational basis of each and every regulation and the ban on drilling.

  1. Fishing amplifies forage fish population collapses.

    PubMed

    Essington, Timothy E; Moriarty, Pamela E; Froehlich, Halley E; Hodgson, Emma E; Koehn, Laura E; Oken, Kiva L; Siple, Margaret C; Stawitz, Christine C

    2015-05-26

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches.

  2. Interactions Increase Forager Availability and Activity in Harvester Ants.

    PubMed

    Pless, Evlyn; Queirolo, Jovel; Pinter-Wollman, Noa; Crow, Sam; Allen, Kelsey; Mathur, Maya B; Gordon, Deborah M

    2015-01-01

    Social insect colonies use interactions among workers to regulate collective behavior. Harvester ant foragers interact in a chamber just inside the nest entrance, here called the 'entrance chamber'. Previous studies of the activation of foragers in red harvester ants show that an outgoing forager inside the nest experiences an increase in brief antennal contacts before it leaves the nest to forage. Here we compare the interaction rate experienced by foragers that left the nest and ants that did not. We found that ants in the entrance chamber that leave the nest to forage experienced more interactions than ants that descend to the deeper nest without foraging. Additionally, we found that the availability of foragers in the entrance chamber is associated with the rate of forager return. An increase in the rate of forager return leads to an increase in the rate at which ants descend to the deeper nest, which then stimulates more ants to ascend into the entrance chamber. Thus a higher rate of forager return leads to more available foragers in the entrance chamber. The highest density of interactions occurs near the nest entrance and the entrances of the tunnels from the entrance chamber to the deeper nest. Local interactions with returning foragers regulate both the activation of waiting foragers and the number of foragers available to be activated.

  3. Information Foraging for Perceptual Decisions

    PubMed Central

    2016-01-01

    We tested an information foraging framework to characterize the mechanisms that drive active (visual) sampling behavior in decision problems that involve multiple sources of information. Experiments 1 through 3 involved participants making an absolute judgment about the direction of motion of a single random dot motion pattern. In Experiment 4, participants made a relative comparison between 2 motion patterns that could only be sampled sequentially. Our results show that: (a) Information (about noisy motion information) grows to an asymptotic level that depends on the quality of the information source; (b) The limited growth is attributable to unequal weighting of the incoming sensory evidence, with early samples being weighted more heavily; (c) Little information is lost once a new source of information is being sampled; and (d) The point at which the observer switches from 1 source to another is governed by online monitoring of his or her degree of (un)certainty about the sampled source. These findings demonstrate that the sampling strategy in perceptual decision-making is under some direct control by ongoing cognitive processing. More specifically, participants are able to track a measure of (un)certainty and use this information to guide their sampling behavior. PMID:27819455

  4. Experiment study of the motion of the floating offshore turbine

    NASA Astrophysics Data System (ADS)

    Chuang, Tzu-Ching; Hsu, Wen-Yang; Yang, Ray-Yeng; Chen, Yang-Yi

    2016-04-01

    Recently the wind industry moved to offshore areas. The floating wind turbine combined the platform and the mooring system. This research focuses on studying the motion of the floating offshore turbine with a mooring system. The platform, which was developed by the Ship and Ocean Industries R&D Center, had been test in a wave-wind flume in the Tainan Hydraulics Laboratory by using a 1:50 Froude scaling model. In the experiment, the floating offshore turbine was placed in a water flume and exposed to periodic waves at frequencies ranging from 0.22 rad/s - 0.875 rad/s, the wave amplitude is about 2.5 meter, and with the different pretension of the mooring lines. The experiment includes the measurement of damping coefficient from the free decay test and the dynamic response in a sea state. This research compares the motion of the floating offshore turbine with the different pretension of the mooring lines, and the model provides comprehensive data for the operational, design, and survival seas states, as well as the calibration and improvement of the existing design and performance of numerical models.

  5. Investigation of the Hosgri Fault, offshore Southern California, Point Sal to Point Conception

    USGS Publications Warehouse

    Payne, C.M.; Swanson, O.E.; Schell, B.A.

    1979-01-01

    A high-resolution seismic reflection survey of the inner continental shelf between Point Sal and Point Conception has revealed faults that displace post-Wisconsin strata (less than 17,000-20,000 years). These faults are the Hosgri fault, the Offshore Lompoc fault, and smaller unnamed faults. Faults trending offshore from the adjacent shoreline such as the Pezzoni, Lions Head, Honda, and Pacifico faults, do not show post-Wisconsin activity. The Hosgri fault trends directly toward the coastline between Purisima Point and Point Arguello where it appears to merge with folds and smaller faults in the western Transverse Ranges. This trend of offshore structures toward the Point Arguello-Point Conception area is consistent with a hypothesis that the regional structural fabric of the southern California Coast Ranges and its adjacent offshore area merge with the Transverse Ranges.

  6. Good Days, Bad Days: Wind as a Driver of Foraging Success in a Flightless Seabird, the Southern Rockhopper Penguin

    PubMed Central

    Dehnhard, Nina; Ludynia, Katrin; Poisbleau, Maud; Demongin, Laurent; Quillfeldt, Petra

    2013-01-01

    Due to their restricted foraging range, flightless seabirds are ideal models to study the short-term variability in foraging success in response to environmentally driven food availability. Wind can be a driver of upwelling and food abundance in marine ecosystems such as the Southern Ocean, where wind regime changes due to global warming may have important ecological consequences. Southern rockhopper penguins (Eudyptes chrysocome) have undergone a dramatic population decline in the past decades, potentially due to changing environmental conditions. We used a weighbridge system to record daily foraging mass gain (the difference in mean mass of adults leaving the colony in the morning and returning to the colony in the evening) of adult penguins during the chick rearing in two breeding seasons. We related the day-to-day variability in foraging mass gain to ocean wind conditions (wind direction and wind speed) and tested for a relationship between wind speed and sea surface temperature anomaly (SSTA). Foraging mass gain was highly variable among days, but did not differ between breeding seasons, chick rearing stages (guard and crèche) and sexes. It was strongly correlated between males and females, indicating synchronous changes among days. There was a significant interaction of wind direction and wind speed on daily foraging mass gain. Foraging mass gain was highest under moderate to strong winds from westerly directions and under weak winds from easterly directions, while decreasing under stronger easterly winds and storm conditions. Ocean wind speed showed a negative correlation with daily SSTA, suggesting that winds particularly from westerly directions might enhance upwelling and consequently the prey availability in the penguins' foraging areas. Our data emphasize the importance of small-scale, wind-induced patterns in prey availability on foraging success, a widely neglected aspect in seabird foraging studies, which might become more important with increasing

  7. Good days, bad days: wind as a driver of foraging success in a flightless seabird, the southern rockhopper penguin.

    PubMed

    Dehnhard, Nina; Ludynia, Katrin; Poisbleau, Maud; Demongin, Laurent; Quillfeldt, Petra

    2013-01-01

    Due to their restricted foraging range, flightless seabirds are ideal models to study the short-term variability in foraging success in response to environmentally driven food availability. Wind can be a driver of upwelling and food abundance in marine ecosystems such as the Southern Ocean, where wind regime changes due to global warming may have important ecological consequences. Southern rockhopper penguins (Eudyptes chrysocome) have undergone a dramatic population decline in the past decades, potentially due to changing environmental conditions. We used a weighbridge system to record daily foraging mass gain (the difference in mean mass of adults leaving the colony in the morning and returning to the colony in the evening) of adult penguins during the chick rearing in two breeding seasons. We related the day-to-day variability in foraging mass gain to ocean wind conditions (wind direction and wind speed) and tested for a relationship between wind speed and sea surface temperature anomaly (SSTA). Foraging mass gain was highly variable among days, but did not differ between breeding seasons, chick rearing stages (guard and crèche) and sexes. It was strongly correlated between males and females, indicating synchronous changes among days. There was a significant interaction of wind direction and wind speed on daily foraging mass gain. Foraging mass gain was highest under moderate to strong winds from westerly directions and under weak winds from easterly directions, while decreasing under stronger easterly winds and storm conditions. Ocean wind speed showed a negative correlation with daily SSTA, suggesting that winds particularly from westerly directions might enhance upwelling and consequently the prey availability in the penguins' foraging areas. Our data emphasize the importance of small-scale, wind-induced patterns in prey availability on foraging success, a widely neglected aspect in seabird foraging studies, which might become more important with increasing

  8. Field Margins, Foraging Distances and Their Impacts on Nesting Pollinator Success

    PubMed Central

    Rands, Sean A.; Whitney, Heather M.

    2011-01-01

    The areas of wild land around the edges of agricultural fields are a vital resource for many species. These include insect pollinators, to whom field margins provide both nest sites and important resources (especially when adjacent crops are not in flower). Nesting pollinators travel relatively short distances from the nest to forage: most species of bee are known to travel less than two kilometres away. In order to ensure that these pollinators have sufficient areas of wild land within reach of their nests, agricultural landscapes need to be designed to accommodate the limited travelling distances of nesting pollinators. We used a spatially-explicit modelling approach to consider whether increasing the width of wild strips of land within the agricultural landscape will enhance the amount of wild resources available to a nesting pollinator, and if it would impact differently on pollinators with differing foraging strategies. This was done both by creating field structures with a randomised geography, and by using landscape data based upon the British agricultural landscape. These models demonstrate that enhancing field margins should lead to an increase in the availability of forage to pollinators that nest within the landscape. With the exception of species that only forage within a very short range of their nest (less than 125 m), a given amount of field margin manipulation should enhance the proportion of land available to a pollinator for foraging regardless of the distance over which it normally travels to find food. A fixed amount of field edge manipulation should therefore be equally beneficial for both longer-distance nesting foragers such as honeybees, and short-distance foragers such as solitary bees. PMID:21991390

  9. Foraging patterns of Caspian terns and double-crested cormorants in the Columbia River estuary

    USGS Publications Warehouse

    Lyons, Donald E.; Roby, D.D.; Collis, K.

    2007-01-01

    We examined spatial and temporal foraging patterns of Caspian terns and double-crested cormorants nesting in the Columbia River estuary, to potentially identify circumstances where juvenile salmonids listed under the U.S. Endangered Species Act might be more vulnerable to predation by these avian piscivores. Data were collected during the 1998 and 1999 breeding seasons, using point count surveys of foraging birds at 40 sites along the river's banks, and using aerial strip transect counts throughout the estuary for terns. In 1998, terns selected tidal flats and sites with roosting beaches nearby for foraging, making greater use of the marine/mixing zone of the estuary later in the season, particularly areas near the ocean jetties. In 1999, cormorants selected foraging sites in freshwater along the main channel with pile dikes present, particularly early in the season. Foraging trends in the other year for each species were generally similar to the above but usually not significant. During aerial surveys we observed 50% of foraging and commuting terns within 8 km of the Rice Island colony, and ??? 5% of activity occurred ??? 27 km from this colony in both years. Disproportionately greater cormorant foraging activity at pile dikes may indicate greater vulnerability of salmonids to predation at those features. Colony relocations to sites at sufficient distance from areas of relatively high salmonid abundance may be a straightforward means of reducing impacts of avian predation on salmonids than habitat alterations within the Columbia River estuary, at least for terns. ?? 2007 by the Northwest Scientific Association. All rights reserved.

  10. Offshore survey provides answers to coastal stability and potential offshore extensions of landslides into Abalone Cove, Palos Verdes peninsula, Calif

    SciTech Connect

    Dill, R.F. ); Slosson, J.E. )

    1993-04-01

    The configuration and stability of the present coast line near Abalone Cove, on the south side of Palos Verdes Peninsula, California is related to the geology, oceanographic conditions, and recent and ancient landslide activity. This case study utilizes offshore high resolution seismic profiles, side-scan sonar, diving, and coring, to relate marine geology to the stability of a coastal region with known active landslides utilizing a desk top computer and off-the-shelf software. Electronic navigation provided precise positioning that when applied to computer generated charts permitted correlation of survey data needed to define the offshore geology and sea floor sediment patterns. A mackintosh desk-top computer and commercially available off-the-shelf software provided the analytical tools for constructing a base chart and a means to superimpose template overlays of topography, isopachs or sediment thickness, bottom roughness and sediment distribution patterns. This composite map of offshore geology and oceanography was then related to an extensive engineering and geological land study of the coastal zone forming Abalone Cove, an area of active landslides. Vibrocoring provided ground sediment data for high resolution seismic traverses. This paper details the systems used, present findings relative to potential landslide movements, coastal erosion and discuss how conclusions were reached to determine whether or not onshore landslide failures extend offshore.

  11. Four barges mobilized for job: Indian offshore pipeline work demands comprehensive coordination

    SciTech Connect

    Schmidt, J. )

    1994-02-01

    This paper describes the design, installation, and commissioning timeframe developed for the Oil and Natural Gas Commission of India. Offshore Hyundai International Inc. and Offshore Pipelines International have completed the installation of 47 pipelines, six platforms, and a single-point mooring system in the Arabian Sea. The coordination and work scheduling problems are described along with the engineered placement of the pipelines in an already congested area.

  12. Probability based earthquake load and resistance factor design criteria for offshore platforms

    SciTech Connect

    Bea, R.G.

    1996-12-31

    This paper describes a probability reliability based formulation to determine earthquake Load and Resistance Factor Design (LRFD) parameters for conventional, steel, pile supported, tubular membered platforms that is proposed as a basis for earthquake design criteria and guidelines for offshore platforms that are intended to have worldwide applicability. The formulation is illustrated with application to platforms located in five areas: offshore California, Venezuela (Rio Caribe), the East Coast of Canada, in the Caspian Sea (Azeri), and the Norwegian sector of the North Sea.

  13. Relationship between marine mammal stranding events and offshore earthquakes

    NASA Astrophysics Data System (ADS)

    Grant, Rachel; Savirina, Anna; Hoppit, Will

    2014-05-01

    The causes of marine mammal stranding events are largely unknown, but may relate to ocean currents, severe weather, anthropogenic noise pollution, and other factors. Large stranding events have been suggested to occur as a result of offshore earthquakes but there is little evidence as yet to support this hypothesis. Stranding events occur in hotspots, which are sometimes areas of high seismic activity, such as Taiwan, and other times, in areas that are removed from seismic zones, such as Cape Cod. We analyse a large and robust dataset of marine mammal stranding data collected off the coast of Washington and Oregon from 1999 to 2010, to look for statistical connections to offshore earthquakes. We looked forward, as well as backward in time from significant seismic events, to ascertain whether stranding occurrences, if connected to earthquakes, are a result of the earthquake preparation period or the earthquake itself. Possible mechanisms are discussed.

  14. An application of numerical simulation techniques to improve the resolution of offshore fault kinematics using seafloor geodetic methods

    NASA Astrophysics Data System (ADS)

    Nishimura, Sou; Ando, Masataka; Tadokoro, Keiichi

    2005-08-01

    Geodetic measurements reveal a number of tectonic phenomena, such as coseismic and postseismic displacements of earthquakes and interplate coupling on plate interfaces. However, since geodetic measurements are limited to land, slip distribution is poorly resolved offshore, though well constrained in the landward areas. Due to the poverty of offshore data, tectonic motion near trench axes has not been measured. Seafloor geodetic observations provide important information on offshore tectonics. Improved offshore resolution would allow determination of strain accumulation and release processes near trench axes. In this study, using numerical simulation, we discuss the potential for improvement of slip resolution in an offshore area using seafloor geodetic measurements. The plate interface along the Nankai trough is modeled by 36 planar fault segments, whose length and width, respectively, are set to 60 km and 50 km. Three hundred and seventy-five GPS observation sites on land and 10 seafloor sites aligned 60 km off the coast are used for the simulation. We carry out a checkerboard test and compare the estimated slip pattern with the given checkerboard pattern. Models that do not include seafloor sites generate large discrepancies in offshore deformation between the initial and estimated slip patterns, although there are similarities in coastal regions. This indicates poor resolution in offshore areas. When we apply our model to include seafloor sites, the difference between the initial and estimated slip patterns decreases for most of the modeled fault segments. Comparison between these two cases suggests the potential for use of seafloor geodetic techniques to improve offshore resolution.

  15. Offshore and arctic frontiers -structures, ocean mining

    SciTech Connect

    Chung, J.S.

    1985-05-01

    The systematic development of offshore technology is discussed. Today, this technology enables the production of approximately 14 million barrels of oil per day, or 26% of oil production worldwide. The evolution in offshore structures is examined with emphasis on jacket and jackup platforms. Challenges are explored. Microprocessors, data-base management, and artificial intelligence are mentioned as having an impact on the offshore and arctic oil industry.

  16. Forage and bioenergy feedstock production from hybrid forage sorghum and sorghum x sudangrass hybrids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the bioenergy industry expands, producers choosing to shift current forage crop production to dedicated biomass crops will find it advantageous to grow low risk multi-purpose crops that maximize management options. Hybrid forage sorghums (HFS) and sorghum by sudangrass hybrids (SSG) are capable...

  17. Transport infrastructure shapes foraging habitat in a raptor community.

    PubMed

    Planillo, Aimara; Kramer-Schadt, Stephanie; Malo, Juan E

    2015-01-01

    Transport infrastructure elements are widespread and increasing in size and length in many countries, with the subsequent alteration of landscapes and wildlife communities. Nonetheless, their effects on habitat selection by raptors are still poorly understood. In this paper, we analyzed raptors' foraging habitat selection in response to conventional roads and high capacity motorways at the landscape scale, and compared their effects with those of other variables, such as habitat structure, food availability, and presence of potential interspecific competitors. We also analyzed whether the raptors' response towards infrastructure depends on the spatial scale of observation, comparing the attraction or avoidance behavior of the species at the landscape scale with the response of individuals observed in the proximity of the infrastructure. Based on ecological hypotheses for foraging habitat selection, we built generalized linear mixed models, selected the best models according to Akaike Information Criterion and assessed variable importance by Akaike weights. At the community level, the traffic volume was the most relevant variable in the landscape for foraging habitat selection. Abundance, richness, and diversity values reached their maximum at medium traffic volumes and decreased at highest traffic volumes. Individual species showed different degrees of tolerance toward traffic, from higher abundance in areas with high traffic values to avoidance of it. Medium-sized opportunistic raptors increased their abundance near the traffic infrastructures, large scavenger raptors avoided areas with higher traffic values, and other species showed no direct response to traffic but to the presence of prey. Finally, our cross-scale analysis revealed that the effect of transport infrastructures on the behavior of some species might be detectable only at a broad scale. Also, food availability may attract raptor species to risky areas such as motorways.

  18. Transport Infrastructure Shapes Foraging Habitat in a Raptor Community

    PubMed Central

    Planillo, Aimara; Kramer-Schadt, Stephanie; Malo, Juan E.

    2015-01-01

    Transport infrastructure elements are widespread and increasing in size and length in many countries, with the subsequent alteration of landscapes and wildlife communities. Nonetheless, their effects on habitat selection by raptors are still poorly understood. In this paper, we analyzed raptors’ foraging habitat selection in response to conventional roads and high capacity motorways at the landscape scale, and compared their effects with those of other variables, such as habitat structure, food availability, and presence of potential interspecific competitors. We also analyzed whether the raptors’ response towards infrastructure depends on the spatial scale of observation, comparing the attraction or avoidance behavior of the species at the landscape scale with the response of individuals observed in the proximity of the infrastructure. Based on ecological hypotheses for foraging habitat selection, we built generalized linear mixed models, selected the best models according to Akaike Information Criterion and assessed variable importance by Akaike weights. At the community level, the traffic volume was the most relevant variable in the landscape for foraging habitat selection. Abundance, richness, and diversity values reached their maximum at medium traffic volumes and decreased at highest traffic volumes. Individual species showed different degrees of tolerance toward traffic, from higher abundance in areas with high traffic values to avoidance of it. Medium-sized opportunistic raptors increased their abundance near the traffic infrastructures, large scavenger raptors avoided areas with higher traffic values, and other species showed no direct response to traffic but to the presence of prey. Finally, our cross-scale analysis revealed that the effect of transport infrastructures on the behavior of some species might be detectable only at a broad scale. Also, food availability may attract raptor species to risky areas such as motorways. PMID:25786218

  19. 1991 worldwide offshore contractors and equipment directory

    SciTech Connect

    Not Available

    1991-01-01

    This book is the information source-book for the international offshore oil industry. Within this single convenient reference you'll find addresses, phone numbers, telex, fax and cable listings for more than 3,500 companies and their key personnel in the drilling, workover, construction, service/supply/manufacturers, geophysical, diving and transportation segments of the offshore industry. Along with this vital contact information, the authors include such pertinent data as rig specifications, ownership, an equipment index, a company index and a current survey of offshore production systems from Offshore Incorporating the Oilman.

  20. Flooding tolerance of forage legumes.

    PubMed

    Striker, Gustavo G; Colmer, Timothy D

    2016-06-20

    We review waterlogging and submergence tolerances of forage (pasture) legumes. Growth reductions from waterlogging in perennial species ranged from >50% for Medicago sativa and Trifolium pratense to <25% for Lotus corniculatus, L. tenuis, and T. fragiferum For annual species, waterlogging reduced Medicago truncatula by ~50%, whereas Melilotus siculus and T. michelianum were not reduced. Tolerant species have higher root porosity (gas-filled volume in tissues) owing to aerenchyma formation. Plant dry mass (waterlogged relative to control) had a positive (hyperbolic) relationship to root porosity across eight species. Metabolism in hypoxic roots was influenced by internal aeration. Sugars accumulate in M. sativa due to growth inhibition from limited respiration and low energy in roots of low porosity (i.e. 4.5%). In contrast, L. corniculatus, with higher root porosity (i.e. 17.2%) and O2 supply allowing respiration, maintained growth better and sugars did not accumulate. Tolerant legumes form nodules, and internal O2 diffusion along roots can sustain metabolism, including N2 fixation, in submerged nodules. Shoot physiology depends on species tolerance. In M. sativa, photosynthesis soon declines and in the longer term (>10 d) leaves suffer chlorophyll degradation, damage, and N, P, and K deficiencies. In tolerant L corniculatus and L. tenuis, photosynthesis is maintained longer, shoot N is less affected, and shoot P can even increase during waterlogging. Species also differ in tolerance of partial and complete shoot submergence. Gaps in knowledge include anoxia tolerance of roots, N2 fixation during field waterlogging, and identification of traits conferring the ability to recover after water subsides.

  1. Onshore-offshore movement of jumbo squid (Dosidicus gigas) on the continental shelf

    NASA Astrophysics Data System (ADS)

    Stewart, Julia S.; Gilly, William F.; Field, John C.; Payne, John C.

    2013-10-01

    Jumbo squid (Dosidicus gigas) have greatly extended their range in the California Current System, where they forage on a variety of ecologically and economically important species that inhabit both coastal and offshore mesopelagic regions. Swimming abilities and behavior are important factors in assessing the impacts of this range expansion, particularly in regard to foraging in conjunction with onshore-offshore movement over the continental shelf. Here we describe a study of horizontal movements by jumbo squid along and across the continental shelf off Washington, USA, using acoustic tags in association with the Census of Marine Life's Pacific Ocean Shelf Tracking Program (POST) receiver arrays. We detected frequent movements along the shelf break, movement onto the shelf at night, and no evidence of movement as a cohesive school. Our results demonstrate feasibility of using acoustic tags and arrays to document horizontal movements of jumbo squid along and across the continental shelf. This is important in order to determine how those movements overlap with those of other ecologically and commercially important fish species.

  2. Macronutrient modifications of optimal foraging theory: an approach using indifference curves applied to some modern foragers

    SciTech Connect

    Hill, K.

    1988-06-01

    The use of energy (calories) as the currency to be maximized per unit time in Optimal Foraging Models is considered in light of data on several foraging groups. Observations on the Ache, Cuiva, and Yora foragers suggest men do not attempt to maximize energetic return rates, but instead often concentration on acquiring meat resources which provide lower energetic returns. The possibility that this preference is due to the macronutrient composition of hunted and gathered foods is explored. Indifference curves are introduced as a means of modeling the tradeoff between two desirable commodities, meat (protein-lipid) and carbohydrate, and a specific indifference curve is derived using observed choices in five foraging situations. This curve is used to predict the amount of meat that Mbuti foragers will trade for carbohydrate, in an attempt to test the utility of the approach.

  3. Barbastelle bats ( Barbastella spp.) specialize in the predation of moths: implications for foraging tactics and conservation

    NASA Astrophysics Data System (ADS)

    Sierro, Antoine; Arlettaz, Raphaël

    The diet of barbastelle bats, Barbastella (b.) barbastellus and B. (b.) leucomelas, captured, respectively, in the Swiss Alps and in the Kirghiz Tien Shian and Pamir mountains (central Asia) was investigated through faecal analysis. Location of hunting habitats and data on foraging behaviour of Swiss barbastelle bats were obtained from radiotracking. In either area, ca. 99% of prey by volume consisted of Lepidoptera. The regular occurrence of one small arctiid species in the diet of Swiss barbastelles, as well as the predominance (84%) of tympanate moths among the Lepidoptera sampled at foraging sites suggest that B. barbastellus could prey to a large extent on smaller tympanate moths. Observations of foraging bats showed that, in the study area, barbastelles behaved as typical aerialhawking bat species, although they hunted exclusively just above the forest canopy. This aerial-hawking bat species has seemingly evolved a peculiar foraging technique to overcome the defence system of its probable tympanate prey. The diet of Barbastella appears one of the narrowest among Palaearctic bats. Such a specialization in foraging habits probably points to a higher vulnerability of this species, as compared to other more flexible aerial-hawking bats, to negative changes in the abundance of moth populations. This could explain its current rarity throughout most of Europe.

  4. Characterizing Variation of Isotopic Markers in Northern Alaskan Caribou Forages

    NASA Astrophysics Data System (ADS)

    VanSomeren, L.; Barboza, P. S.; Gustine, D. D.; Parrett, L. S.; Stricker, C. A.

    2013-12-01

    Isotopic markers in feces and tissues are a potential tool for monitoring the importance of feeding areas for migratory herbivores such as caribou (Rangifer tarandus). Many of these techniques are currently limited by gaps in our knowledge of how these isotopic signatures vary over the landscape. We collected seven species of preferred caribou forages along a latitudinal gradient in the summer ranges of the Central Arctic (9 sites) and Teshekpuk Lake (4 sites) caribou herds during 2011 and 2012. We analyzed forages at peak protein content and at the end of the season to characterize temporal, species-specific, and spatial variation in isotopic markers. The availability of C and N was measured by digestion in vitro. Isotopic signatures of digested samples were used to calculate fractionation that would bias the isotopic signature of feces. The range of values for isotopes (all values ‰) of nitrogen (δ15N -9.5 - +4.3), and sulfur (δ34S -3.6 - +15.5) were greater than those for carbon (δ13C -30.5 - -24.9). Small declines in forage δ13C with latitude (Carex aquatilis, Eriophorum vaginatum, Salix pulchra, and S. richardsonii [all P < 0.01]), season (all species except C. bigelowii [all P ≤ 0.01]), and season x year (S. richardsonii; P = 0.01) were probably associated with changes in water availability. Fractionation of δ13C in early season forages was 0.1 × 1.0 and positively related to C availability (58% × 15%; P < 0.01) with the greatest fractionation for the highly digestible forb Pedicularis langsdorfii (1.43 × 0.44; P < 0.01). Sedges (Carex and Eriophorum) were significantly higher in δ15N than Salix spp. and other dicots (2.0 × 1.1 vs. -2.9 × 2.2; P < 0.01). For Salix spp., δ15N was consistent over the season and between years. Fractionation of δ15N in early season forages was 0.2 × 1.8 and not related to N availability (60% × 17%). For S. pulchra, δ34S may indicate usage of coastal habitats over foothills because δ34S was higher on the

  5. Effects of sea state on offshore wind resourcing in Florida

    NASA Astrophysics Data System (ADS)

    Collier, Cristina

    Offshore resource assessment relies on estimating wind speeds at turbine hub height using observations typically made at substantially lower height. The methods used to adjust from observed wind speeds to hub height can impact resource estimation. The importance of directional sea state is examined, both as seasonal averages and as a function of the diurnal cycle. A General Electric 3.6 MW offshore turbine is used as a model for a power production. Including sea state increases or decreases seasonally averaged power production by roughly 1%, which is found to be an economically significant change. These changes occur because the sea state modifies the wind shear (vector wind difference between the buoy height and the moving surface) and therefore the extrapolation from the observation to hub height is affected. These seemingly small differences in capacity can alter profits by millions of dollars depending upon the size of the farm and fluctuations in price per kWh throughout the year. A 2% change in capacity factor can lead to a 10 million dollar difference from total kWh produced from a wind farm of 100 3.6MW turbines. These economic impacts can be a deciding factor in determining whether a resource is viable for development. Modification of power output due to sea states are shown for seasonal and diurnal time scales. Three regions are examined herein: West Florida, East Florida, and Nantucket Sound. The average capacity after sea state is included suggests areas around Florida could provide substantial amounts of wind power throughout three-fourths of the calendar year. At certain times of day winter average produced capacity factors in West Florida can be up to 45% more than in summer when sea state is included. Nantucket Sound capacity factors are calculated for comparison to a region near a planned United States offshore wind farm. This study provides evidence to suggest including sea state in offshore wind resource assessment causes economically significant

  6. Roosting and Foraging Social Structure of the Endangered Indiana Bat (Myotis sodalis)

    PubMed Central

    Silvis, Alexander; Kniowski, Andrew B.; Gehrt, Stanley D.; Ford, W. Mark

    2014-01-01

    Social dynamics are an important but poorly understood aspect of bat ecology. Herein we use a combination of graph theoretic and spatial approaches to describe the roost and social network characteristics and foraging associations of an Indiana bat (Myotis sodalis) maternity colony in an agricultural landscape in Ohio, USA. We tracked 46 bats to 50 roosts (423 total relocations) and collected 2,306 foraging locations for 40 bats during the summers of 2009 and 2010. We found the colony roosting network was highly centralized in both years and that roost and social networks differed significantly from random networks. Roost and social network structure also differed substantially between years. Social network structure appeared to be unrelated to segregation of roosts between age classes. For bats whose individual foraging ranges were calculated, many shared foraging space with at least one other bat. Compared across all possible bat dyads, 47% and 43% of the dyads showed more than expected overlap of foraging areas in 2009 and 2010 respectively. Colony roosting area differed between years, but the roosting area centroid shifted only 332 m. In contrast, whole colony foraging area use was similar between years. Random roost removal simulations suggest that Indiana bat colonies may be robust to loss of a limited number of roosts but may respond differently from year to year. Our study emphasizes the utility of graphic theoretic and spatial approaches for examining the sociality and roosting behavior of bats. Detailed knowledge of the relationships between social and spatial aspects of bat ecology could greatly increase conservation effectiveness by allowing more structured approaches to roost and habitat retention for tree-roosting, socially-aggregating bat species. PMID:24816811

  7. 76 FR 39410 - National Offshore Safety Advisory Committee; Vacancies

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-06

    ..., of offshore mineral and oil operations including geophysical services; (b) One member representing construction of offshore exploration and recovery facilities; (c) One member representing employees of... the exploration for and the recovery of offshore mineral resources. Registered lobbyists are...

  8. Use of chemical tracers in assessing the diet and foraging regions of eastern North Pacific killer whales.

    PubMed

    Krahn, Margaret M; Herman, David P; Matkin, Craig O; Durban, John W; Barrett-Lennard, Lance; Burrows, Douglas G; Dahlheim, Marilyn E; Black, Nancy; LeDuc, Richard G; Wade, Paul R

    2007-03-01

    Top predators in the marine environment integrate chemical signals acquired from their prey that reflect both the species consumed and the regions from which the prey were taken. These chemical tracers-stable isotope ratios of carbon and nitrogen; persistent organic pollutant (POP) concentrations, patterns and ratios; and fatty acid profiles-were measured in blubber biopsy samples from North Pacific killer whales (Orcinus orca) (n=84) and were used to provide further insight into their diet, particularly for the offshore group, about which little dietary information is available. The offshore killer whales were shown to consume prey species that were distinctly different from those of sympatric resident and transient killer whales. In addition, it was confirmed that the offshores forage as far south as California. Thus, these results provide evidence that the offshores belong to a third killer whale ecotype. Resident killer whale populations showed a gradient in stable isotope profiles from west (central Aleutians) to east (Gulf of Alaska) that, in part, can be attributed to a shift from off-shelf to continental shelf-based prey. Finally, stable isotope ratio results, supported by field observations, showed that the diet in spring and summer of eastern Aleutian Island transient killer whales is apparently not composed exclusively of Steller sea lions.

  9. Body size affects individual winter foraging strategies of thick-billed murres in the Bering Sea.

    PubMed

    Orben, Rachael A; Paredes, Rosana; Roby, Daniel D; Irons, David B; Shaffer, Scott A

    2015-11-01

    Foraging and migration often require different energetic and movement strategies. Though not readily apparent, constraints during one phase might influence the foraging strategies observed in another. For marine birds that fly and dive, body size constraints likely present a trade-off between foraging ability and migration as smaller bodies reduce flight costs, whereas larger bodies are advantageous for diving deeper. This study examines individual wintering strategies of deep diving thick-billed murres (Uria lomvia) breeding at three colonies in the south-eastern Bering Sea: St Paul, St George and Bogoslof. These colonies, arranged north to south, are located such that breeding birds forage in a gradient from shelf to deep-water habitats. We used geolocation time-depth recorders and stable isotopes from feathers to determine differences in foraging behaviour and diet of murres during three non-breeding periods, 2008-2011. Body size was quantified by a principal component analysis (wing, culmen, head+bill and tarsus length). A hierarchical cluster analysis identified winter foraging strategies based on individual movement, diving behaviour and diet (inferred from stable isotopes). Structural body size differed by breeding island. Larger birds from St Paul had higher wing loading than smaller birds from St George. Larger birds, mainly from St Paul, dove to deeper depths, spent more time in the Bering Sea, and likely consumed higher trophic-level prey in late winter. Three winter foraging strategies were identified. The main strategy, employed by small birds from all three breeding colonies in the first 2 years, was characterized by high residency areas in the North Pacific south of the Aleutians and nocturnal diving. In contrast, 31% of birds from St Paul remained in the Bering Sea and foraged mainly during the day, apparently feeding on higher trophic-level prey. Throat feather stable isotopes indicated that individuals exhibited flexibility in the use of this

  10. Central-place foraging and ecological effects of an invasive predator across multiple habitats.

    PubMed

    Benkwitt, Cassandra E

    2016-10-01

    Cross-habitat foraging movements of predators can have widespread implications for predator and prey populations, community structure, nutrient transfer, and ecosystem function. Although central-place foraging models and other aspects of optimal foraging theory focus on individual predator behavior, they also provide useful frameworks for understanding the effects of predators on prey populations across multiple habitats. However, few studies have examined both the foraging behavior and ecological effects of nonnative predators across multiple habitats, and none has tested whether nonnative predators deplete prey in a manner predicted by these foraging models. I conducted behavioral observations of invasive lionfish (Pterois volitans) to determine whether they exhibit foraging movements similar to other central-place consumers. Then, I used a manipulative field experiment to test whether their effects on prey populations are consistent with three qualitative predictions from optimal foraging models. Specifically, I predicted that the effects of invasive lionfish on native prey will (1) occur at central sites first and then in surrounding habitats, (2) decrease with increasing distance away from their shelter site, and (3) extend to greater distances when prey patches are spaced closer together. Approximately 40% of lionfish exhibited short-term crepuscular foraging movements into surrounding habitats from the coral patch reefs where they shelter during daylight hours. Over the course of 7 weeks, lionfish depleted native fish populations on the coral patch reefs where they reside, and subsequently on small structures in the surrounding habitat. However, their effects did not decrease with increasing distance from the central shelter site and the influence of patch spacing was opposite the prediction. Instead, lionfish always had the greatest effects in areas with the highest prey densities. The differences between the predicted and observed effects of lionfish

  11. Evolution of foraging behavior in Drosophilid larvae

    NASA Astrophysics Data System (ADS)

    Rivera-Alba, Marta; Kabra, Mayank; Branson, Kristin; Mirth, Christen

    2015-03-01

    Drosophilids, like other insects, go through a larval phase before metamorphosing into adults. Larvae increase their body weight by several orders of magnitude in a few days. We therefore hypothesized that foraging behavior is under strong evolutionary pressure to best fit the larval environment. To test our hypothesis we used a multidisciplinary approach to analyze foraging behavior across species and larval stages. First, we recorded several videos of larvae foraging for each of 47 Drosophilid species. Then, using a supervised machine learning approach, we automatically annotated the video collection for the foraging sub-behaviors, including crawling, turning, head casting or burrowing. We also computed over 100 features to describe the posture and dynamics of each animal in each video frame. From these data, we fit models to the behavior of each species. The models each had the same parametric form, but differed in the exact parameters. By simulating larva behavior in virtual arenas we can infer which properties of the environments are better for each species. Comparisons between these inferred environments and the actual environments where these animals live will give us a deeper understanding about the evolution of foraging behavior in Drosophilid larvae.

  12. Offshore drilling and production structure

    SciTech Connect

    Crockett, R.K.; Palmer, H.E.; Stenning, D.G.

    1982-02-09

    The invention relates to an off-shore marine structure that provides an elevated support for a drilling and/or production platform. A structure comprised of three interlocking components is provided, the first component being a large foundation base installed on the sea bed; the second being a conical shaped support component which is engagable with the foundation base and which, releasably carries the third platform supporting component. In the preferred form, the platform supporting component comprises a centrally-disposed vertical column, means being provided to facilitate engagement of the column with the platform and the second component and to subsequently elevate the platform to an operating height above sea level.

  13. Seismic assessment for offshore pipelines

    SciTech Connect

    Bruschi, R.; Gudmestad, O.T.; Blaker, F.; Nadim, F.

    1995-12-31

    An international consensus on seismic design criteria for onshore pipelines has been established during the last thirty years. The need to assess seismic design for offshore pipelines has not been similarly recognized. In this paper, the geotechnical hazard for a pipeline routed across steep slopes and irregular terrains affected by earthquakes, is discussed. The integrity of both natural and artificial load bearing supports is assessed.d The response of the pipeline to direct excitation from soil or through discontinuous, sparsely distributed natural or artificial supports, is commented.

  14. Forage digestibility and intake by lesser snow geese: effects of dominance and resource heterogeneity

    USGS Publications Warehouse

    Hupp, Jerry W.; White, Robert G.; Sedinger, James S.; Robertson, Donna G.

    1996-01-01

    We measured forage intake, digestibility, and retention time for 11 free-ranging, human-imprinted lesser snow geese (Chen caerulescens caerulescens) as they consumed underground stembases of tall cotton-grass (Eriophorum angustifolium) on an arctic staging area in northeastern Alaska. Geese fed in small patches (x̄=21.5 m2) of forage that made up ≤3% of the study area and consisted of high-quality “aquatic graminoid” and intermediate-quality “wet sedge” vegetation types. Dominant geese spent more time feeding in aquatic graminoid areas (r=0.61), but less total time feeding and more time resting than subdominant geese. Subdominant geese were displaced to areas of wet sedge where cotton-grass was a smaller proportion of underground biomass. Geese metabolized an average of 48% of the organic matter in stembases and there was a positive correlation between dominance and organic matter metabolizability (r=0.61). Total mean retention time of forage was 1.37 h and dry matter intake was 14.3 g/h. Snow geese that stage on the coastal plain of the Beaufort Sea likely use an extensive area because they consume a large mass of forage and exploit habitats that are patchily distributed and make up a small percentage of the landscape. Individual variation in nutrient absorption may result from agonistic interactions in an environment where resources are heterogeneously distributed.

  15. Offshore Extension of Deccan Traps in Kachchh, Central Western India: Implications for Geological Sequestration Studies

    SciTech Connect

    Pandey, D. K.; Pandey, A.; Rajan, S.

    2011-03-15

    The Deccan basalts in central western India are believed to occupy large onshore-offshore area. Using geophysical and geological observations, onshore sub-surface structural information has been widely reported. On the contrary, information about offshore structural variations has been inadequate due to scarcity of marine geophysical data and lack of onshore-offshore lithological correlations. Till date, merely a few geophysical studies are reported that gauge about the offshore extent of Deccan Traps and the Mesozoic sediments (pre-Deccan). To fill this gap in knowledge, in this article, we present new geophysical evidences to demonstrate offshore continuation of the Deccan volcanics and the Mesozoic sediments. The offshore multi-channel seismic and onshore-offshore lithological correlations presented here confirm that the Mesozoic sedimentary column in this region is overlain by 0.2-1.2-km-thick basaltic cover. Two separate phases of Mesozoic sedimentation, having very distinctive physical and lithological characteristics, are observed between overlying basaltic rocks and underlying Precambrian basement. Using onshore-offshore seismic and borehole data this study provides new insight into the extent of the Deccan basalts and the sub-basalt structures. This study brings out a much clearer picture than that was hitherto available about the offshore continuation of the Deccan Traps and the Mesozoic sediments of Kachchh. Further, its implications in identifying long-term storage of anthropogenic CO{sub 2} within sub-basalt targets are discussed. The carbon sequestration potential has been explored through the geological assessment in terms of the thickness of the strata as well as lithology.

  16. Whole wheat versus mixed layer diet as supplementary feed to layers foraging a sequence of different forage crops.

    PubMed

    Horsted, K; Hermansen, J E

    2007-05-01

    foraging area without negative effects on their health and welfare.

  17. The Relationships between Morphological Characteristics and Foraging Behavior in Four Selected Species of Shorebirds and Water Birds Utilizing Tropical Mudflats

    PubMed Central

    Norazlimi, Nor Atiqah; Ramli, Rosli

    2015-01-01

    A study was conducted to investigate the relationship between the physical morphology of shorebirds and water birds (i.e., Lesser adjutant (Leptoptilos javanicus), Common redshank (Tringa totanus), Whimbrel (Numenius phaeopus), and Little heron (Butorides striata)) and their foraging behavior in the mudflats area of Selangor, Peninsular Malaysia, from August 2013 to July 2014 by using direct observation techniques (using binoculars and a video recorder). The actively foraging bird species were watched, and their foraging activities were recorded for at least 30 seconds for up to a maximum of five minutes. A Spearman Rank Correlation highlighted a significant relationship between bill size and foraging time (R = 0.443, p < 0.05), bill size and prey size (R = −0.052, p < 0.05), bill size and probing depth (R = 0.42, p = 0.003), and leg length and water/mud depth (R = 0.706, p < 0.005). A Kruskal-Wallis Analysis showed a significant difference between average estimates of real probing depth of the birds (mm) and species (H = 15.96, p = 0.0012). Three foraging techniques were recorded: pause-travel, visual-feeding, and tactile-hunting. Thus, morphological characteristics of bird do influence their foraging behavior and strategies used when foraging. PMID:26345324

  18. Dual foraging and pair coordination during chick provisioning by Manx shearwaters: empirical evidence supported by a simple model

    PubMed Central

    Shoji, Akiko; Aris-Brosou, Stéphane; Fayet, Annette; Padget, Oliver; Perrins, Christopher; Guilford, Tim

    2015-01-01

    ABSTRACT The optimal allocation of time and energy between one's own survival and offspring survival is critical for iteroparous animals, but creates a conflict between what maximises the parent's fitness and what maximises fitness of the offspring. For central-place foragers, provisioning strategies may reflect this allocation, while the distance between central-places and foraging areas may influence the decision. Nevertheless, few studies have explored the link between life history and foraging in the context of resource allocation. Studying foraging behaviour alongside food load rates to chicks provides a useful system for understanding the foraging decisions made during parent–offspring conflict. Using simultaneously deployed GPS and time–depth recorders, we examined the provisioning strategies in free-living Manx shearwaters Puffinus puffinus, which were caring for young. Our results showed a bimodal pattern, where birds alternate short and long trips. Short trips were associated with higher feeding frequency and larger meals than long trips, suggesting that long trips were performed for self-feeding. Furthermore, most foraging was carried out within 100 km of sea fronts. A simple model based on patch quality and travel time shows that for Manx shearwaters combining chick feeding and self-maintenance, bimodal foraging trip durations optimise feeding rates. PMID:25964419

  19. Dual foraging and pair coordination during chick provisioning by Manx shearwaters: empirical evidence supported by a simple model.

    PubMed

    Shoji, Akiko; Aris-Brosou, Stéphane; Fayet, Annette; Padget, Oliver; Perrins, Christopher; Guilford, Tim

    2015-07-01

    The optimal allocation of time and energy between one's own survival and offspring survival is critical for iteroparous animals, but creates a conflict between what maximises the parent's fitness and what maximises fitness of the offspring. For central-place foragers, provisioning strategies may reflect this allocation, while the distance between central-places and foraging areas may influence the decision. Nevertheless, few studies have explored the link between life history and foraging in the context of resource allocation. Studying foraging behaviour alongside food load rates to chicks provides a useful system for understanding the foraging decisions made during parent-offspring conflict. Using simultaneously deployed GPS and time-depth recorders, we examined the provisioning strategies in free-living Manx shearwaters Puffinus puffinus, which were caring for young. Our results showed a bimodal pattern, where birds alternate short and long trips. Short trips were associated with higher feeding frequency and larger meals than long trips, suggesting that long trips were performed for self-feeding. Furthermore, most foraging was carried out within 100 km of sea fronts. A simple model based on patch quality and travel time shows that for Manx shearwaters combining chick feeding and self-maintenance, bimodal foraging trip durations optimise feeding rates.

  20. Characterization of winter foraging locations of Adélie penguins along the Western Antarctic Peninsula, 2001-2002

    NASA Astrophysics Data System (ADS)

    Erdmann, Eric S.; Ribic, Christine A.; Patterson-Fraser, Donna L.; Fraser, William R.

    2011-07-01

    In accord with the hypotheses driving the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, we tested the hypothesis that the winter foraging ecology of a major top predator in waters off the Western Antarctic Peninsula (WAP), the Adélie penguin ( Pygoscelis adeliae), is constrained by oceanographic features related to the physiography of the region. This hypothesis grew from the supposition that breeding colonies in the WAP during summer are located adjacent to areas of complex bathymetry where circulation and upwelling processes appear to ensure predictable food resources. Therefore, we tested the additional hypothesis that these areas continue to contribute to the foraging strategy of this species throughout the non-breeding winter season. We used satellite telemetry data collected as part of the SO GLOBEC program during the austral winters of 2001 and 2002 to characterize individual penguin foraging locations in relation to bathymetry, sea ice variability within the pack ice, and wind velocity and divergence (as a proxy for potential areas with cracks and leads). We also explored differences between males and females in core foraging area overlap. Ocean depth was the most influential variable in the determination of foraging location, with most birds focusing their effort on shallow (<200 m) waters near land and on mixed-layer (200-500 m) waters near the edge of deep troughs. Within-ice variability and wind (as a proxy for potential areas with cracks and leads) were not found to be influential variables, which is likely because of the low resolution satellite imagery and model outputs that were available. Throughout the study period, all individuals maintained a core foraging area separated from other individuals with very little overlap. However, from a year with light sea ice to one with heavy ice cover (2001-2002), we observed an increase in the overlap of individual female foraging areas with those of other birds, likely due to

  1. Characterization of winter foraging locations of Adélie penguins along the Western Antarctic Peninsula, 2001–2002

    USGS Publications Warehouse

    Erdmann, Eric S.; Ribic, Christine; Patterson-Fraser, Donna L.; Fraser, William R.

    2011-01-01

    In accord with the hypotheses driving the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, we tested the hypothesis that the winter foraging ecology of a major top predator in waters off the Western Antarctic Peninsula (WAP), the Adélie penguin (Pygoscelis adeliae), is constrained by oceanographic features related to the physiography of the region. This hypothesis grew from the supposition that breeding colonies in the WAP during summer are located adjacent to areas of complex bathymetry where circulation and upwelling processes appear to ensure predictable food resources. Therefore, we tested the additional hypothesis that these areas continue to contribute to the foraging strategy of this species throughout the non-breeding winter season. We used satellite telemetry data collected as part of the SO GLOBEC program during the austral winters of 2001 and 2002 to characterize individual penguin foraging locations in relation to bathymetry, sea ice variability within the pack ice, and wind velocity and divergence (as a proxy for potential areas with cracks and leads). We also explored differences between males and females in core foraging area overlap. Ocean depth was the most influential variable in the determination of foraging location, with most birds focusing their effort on shallow (<200 m) waters near land and on mixed-layer (200–500 m) waters near the edge of deep troughs. Within-ice variability and wind (as a proxy for potential areas with cracks and leads) were not found to be influential variables, which is likely because of the low resolution satellite imagery and model outputs that were available. Throughout the study period, all individuals maintained a core foraging area separated from other individuals with very little overlap. However, from a year with light sea ice to one with heavy ice cover (2001–2002), we observed an increase in the overlap of individual female foraging areas with those of other birds, likely due to

  2. Social Differentiation in Common Bottlenose Dolphins (Tursiops truncatus) that Engage in Human-Related Foraging Behaviors.

    PubMed

    Kovacs, Carolyn J; Perrtree, Robin M; Cox, Tara M

    2017-01-01

    Both natural and human-related foraging strategies by the common bottlenose dolphin (Tursiops truncatus) have resulted in social segregation in several areas of the world. Bottlenose dolphins near Savannah, Georgia beg at an unprecedented rate and also forage behind commercial shrimp trawlers, providing an opportunity to study the social ramifications of two human-related foraging behaviors within the same group of animals. Dolphins were photo-identified via surveys conducted throughout estuarine waterways around Savannah in the summers of 2009-2011. Mean half-weight indices (HWI) were calculated for each foraging class, and community division by modularity was used to cluster animals based on association indices. Pairs of trawler dolphins had a higher mean HWI (0.20 ± 0.07) than pairs of non-trawler dolphins (0.04 ± 0.02) or mixed pairs (0.02 ± 0.02). In contrast, pairs of beggars, non-beggars, and mixed pairs all had similar means, with HWI between 0.05-0.07. Community division by modularity produced a useful division (0.307) with 6 clusters. Clusters were predominately divided according to trawler status; however, beggars and non-beggars were mixed throughout clusters. Both the mean HWI and social clusters revealed that the social structure of common bottlenose dolphins near Savannah, Georgia was differentiated based on trawler status but not beg status. This finding may indicate that foraging in association with trawlers is a socially learned behavior, while the mechanisms for the propagation of begging are less clear. This study highlights the importance of taking into account the social parameters of a foraging behavior, such as how group size or competition for resources may affect how the behavior spreads. The positive or negative ramifications of homophily may influence whether the behaviors are exhibited by individuals within the same social clusters and should be considered in future studies examining social relationships and foraging behaviors.

  3. Social Differentiation in Common Bottlenose Dolphins (Tursiops truncatus) that Engage in Human-Related Foraging Behaviors

    PubMed Central

    2017-01-01

    Both natural and human-related foraging strategies by the common bottlenose dolphin (Tursiops truncatus) have resulted in social segregation in several areas of the world. Bottlenose dolphins near Savannah, Georgia beg at an unprecedented rate and also forage behind commercial shrimp trawlers, providing an opportunity to study the social ramifications of two human-related foraging behaviors within the same group of animals. Dolphins were photo-identified via surveys conducted throughout estuarine waterways around Savannah in the summers of 2009–2011. Mean half-weight indices (HWI) were calculated for each foraging class, and community division by modularity was used to cluster animals based on association indices. Pairs of trawler dolphins had a higher mean HWI (0.20 ± 0.07) than pairs of non-trawler dolphins (0.04 ± 0.02) or mixed pairs (0.02 ± 0.02). In contrast, pairs of beggars, non-beggars, and mixed pairs all had similar means, with HWI between 0.05–0.07. Community division by modularity produced a useful division (0.307) with 6 clusters. Clusters were predominately divided according to trawler status; however, beggars and non-beggars were mixed throughout clusters. Both the mean HWI and social clusters revealed that the social structure of common bottlenose dolphins near Savannah, Georgia was differentiated based on trawler status but not beg status. This finding may indicate that foraging in association with trawlers is a socially learned behavior, while the mechanisms for the propagation of begging are less clear. This study highlights the importance of taking into account the social parameters of a foraging behavior, such as how group size or competition for resources may affect how the behavior spreads. The positive or negative ramifications of homophily may influence whether the behaviors are exhibited by individuals within the same social clusters and should be considered in future studies examining social relationships and foraging behaviors

  4. Planners to the rescue: spatial planning facilitating the development of offshore wind energy.

    PubMed

    Jay, Stephen

    2010-04-01

    The development of offshore wind energy has started to take place surprisingly quickly, especially in North European waters. This has taken the wind energy industry out of the territory of planning systems that usually govern the siting of wind farms on land, and into the world of departmental, sectoral regulation of marine activities. Although this has favoured the expansion of offshore wind energy in some respects, evidence suggests that the practice and principles of spatial planning can make an important contribution to the proper consideration of proposals for offshore wind arrays. This is especially so when a strategic planning process is put in place for marine areas, in which offshore wind is treated as part of the overall configuration of marine interests, so that adjustments can be made in the interests of wind energy. The current process of marine planning in the Netherlands is described as an illustration of this.

  5. Increased Foraging in Outdoor Organic Pig Production—Modeling Environmental Consequences

    PubMed Central

    Jakobsen, Malene; Preda, Teodora; Kongsted, Anne Grete; Hermansen, John Erik

    2015-01-01

    Consumers’ motivations for buying organic products include a wish of acquiring healthy, environmentally friendly products from production systems that also ensure a high level of animal welfare. However, the current Danish organic pig production faces important challenges regarding environmental impact of the system. High ammonia emissions arise from outdoor concrete areas with growing-finishing pigs and sows on pasture possess an increased risk of nitrogen (N) leaching. Direct foraging in the range area is suggested as a way to improve the nutrient efficiency at farm level and to support a more natural behavior of the pig. Thus, by modeling, we investigated the environmental consequences of two alternative scenarios with growing-finishing pigs foraging in the range area and different levels of crops available for foraging; grass-clover (lowest integration of forage) or a combination of lucerne, grass-clover and Jerusalem artichokes (highest integration of forage). It was possible to have growing-finishing pigs on free-range without increasing N leaching compared to the current practice. The alternative system with lucerne, grass-clover and Jerusalem artichokes showed the lowest carbon footprint with 3.12 CO2 eq kg−1 live weight pig compared to the current Danish pasture based system with 3.69 kg CO2 eq kg−1 live weight pig. Due to positive impact on soil carbon sequestration, the second alternative system based on grass-clover  showed a similar carbon foot print compared to current practice with 3.68 kg CO2 eq kg−1 live weight pig. It is concluded that in practice there is room for development of organic pig production systems where direct foraging plays a central role. PMID:28231226

  6. Increased Foraging in Outdoor Organic Pig Production-Modeling Environmental Consequences.

    PubMed

    Jakobsen, Malene; Preda, Teodora; Kongsted, Anne Grete; Hermansen, John Erik

    2015-11-02

    Consumers' motivations for buying organic products include a wish of acquiring healthy, environmentally friendly products from production systems that also ensure a high level of animal welfare. However, the current Danish organic pig production faces important challenges regarding environmental impact of the system. High ammonia emissions arise from outdoor concrete areas with growing pigs and sows on pasture possess an increased risk of nitrogen (N) leaching. Direct foraging in the range area is suggested as a way to improve the nutrient efficiency at farm level and to support a more natural behavior of the pig. Thus, by modeling, we investigated the environmental consequences of two alternative scenarios with growing pigs foraging in the range area and different levels of crops available for foraging-grass-clover or a combination of Jerusalem artichokes and lucerne. It was possible to have growing pigs on free-range without increasing N leaching compared to the current practice. The alternative system with Jerusalem artichokes and lucerne (high integration of forage) showed the lowest carbon foot print with 3.12 CO₂ eq kg(-1) live weight pig compared to the current Danish pasture based system with 3.69 kg CO₂ eq kg(-1) live weight pig. Due to positive impact on soil carbon sequestration, the second alternative system based on grass-clover (low integration of forage) showed a similar carbon foot print compared to current practice with 3.68 kg CO₂ eq kg(-1) live weight pig. It is concluded that in practice there is room for development of organic farming systems where direct foraging plays a central role.

  7. Domestic Options to Offshore Oil and Gas.

    ERIC Educational Resources Information Center

    Kash, Don E.

    1983-01-01

    The continuing controversey over offshore oil/gas has given impetus to searching for domestic energy alternatives. The need for and types of several alternative sources are discussed. Indicates that the United States needs to pursue both offshore and other domestic liquid-fuel sources if it is to avoid becoming increasingly dependent on imports.…

  8. U.S. Offshore Wind Port Readiness

    SciTech Connect

    C. Elkinton, A. Blatiak, H. Ameen

    2013-10-13

    This study will aid decision-makers in making informed decisions regarding the choice of ports for specific offshore projects, and the types of investments that would be required to make individual port facilities suitable to serve offshore wind manufacturing, installation and/or operations.

  9. Deep diving odontocetes foraging strategies and their prey field as determined by acoustic techniques

    NASA Astrophysics Data System (ADS)

    Giorli, Giacomo

    Deep diving odontocetes, like sperm whales, beaked whales, Risso's dolphins, and pilot whales are known to forage at deep depths in the ocean on squid and fish. These marine mammal species are top predators and for this reason are very important for the ecosystems they live in, since they can affect prey populations and control food web dynamics through top-down effects. The studies presented in this thesis investigate deep diving odontocetes. foraging strategies, and the density and size of their potential prey in the deep ocean using passive and active acoustic techniques. Ecological Acoustic Recorders (EAR) were used to monitor the foraging activity of deep diving odontocetes at three locations around the world: the Josephine Seamount High Sea Marine Protected Area (JHSMPA), the Ligurian Sea, and along the Kona coast of the island of Hawaii. In the JHSMPA, sperm whales. and beaked whales. foraging rates do not differ between night-time and day-time. However, in the Ligurian Sea, sperm whales switch to night-time foraging as the winter approaches, while beaked whales alternate between hunting mainly at night, and both at night and at day. Spatial differences were found in deep diving odontocetes. foraging activity in Hawaii where they forage most in areas with higher chlorophyll concentrations. Pilot whales (and false killer whales, clustered together in the category "blackfishes") and Risso's dolphins forage mainly at night at all locations. These two species adjust their foraging activity with the length of the night. The density and size of animals living in deep sea scattering layers was studied using a DIDSON imaging sonar at multiple stations along the Kona coast of Hawaii. The density of animals was affected by location, depth, month, and the time of day. The size of animals was influenced by station and month. The DIDSON proved to be a successful, non-invasive technique to study density and size of animals in the deep sea. Densities were found to be an

  10. Honeybee foraging in differentially structured landscapes.

    PubMed Central

    Steffan-Dewenter, Ingolf; Kuhn, Arno

    2003-01-01

    Honeybees communicate the distance and location of resource patches by bee dances, but this spatial information has rarely been used to study their foraging ecology. We analysed, for the first time to the best of the authors' knowledge, foraging distances and dance activities of honeybees in relation to landscape structure, season and colony using a replicated experimental approach on a landscape scale. We compared three structurally simple landscapes characterized by a high proportion of arable land and large patches, with three complex landscapes with a high proportion of semi-natural perennial habitats and low mean patch size. Four observation hives were placed in the centre of the landscapes and switched at regular intervals between the six landscapes from the beginning of May to the end of July. A total of 1137 bee dances were observed and decoded. Overall mean foraging distance was 1526.1 +/- 37.2 m, the median 1181.5 m and range 62.1-10037.1 m. Mean foraging distances of all bees and foraging distances of nectar-collecting bees did not significantly differ between simple and complex landscapes, but varied between month and colonies. Foraging distances of pollen-collecting bees were significantly larger in simple (1743 +/- 95.6 m) than in complex landscapes (1543.4 +/- 71 m) and highest in June when resources were scarce. Dancing activity, i.e. the number of observed bee dances per unit time, was significantly higher in complex than in simple landscapes, presumably because of larger spatial and temporal variability of resource patches in complex landscapes. The results facilitate an understanding of how human landscape modification may change the evolutionary significance of bee dances and ecological interactions, such as pollination and competition between honeybees and other bee species. PMID:12769455

  11. Quantifying the Hurricane Risk to Offshore Wind Power (Invited)

    NASA Astrophysics Data System (ADS)

    Apt, J.; Rose, S.; Jaramillo, P.; Small, M.

    2013-12-01

    The U.S. Department of Energy has estimated that over 50 GW of offshore wind power will be required for the United States to generate 20% of its electricity from wind. Developers are actively planning offshore wind farms along the U.S. Atlantic and Gulf coasts and several leases have been signed for offshore sites. These planned projects are in areas that are sometimes struck by hurricanes. Whether that risk will grow as a result of climate change is uncertain. Recent years have seen an increase in hurricane activity in the Atlantic basin (1) and, all else being equal, warmer sea surface temperatures can be expected to lead to increased storm intensity. We have developed a method to estimate the catastrophe risk to offshore wind power using simulated hurricanes (2). In Texas, the most vulnerable region we studied, 10% of offshore wind power could be offline simultaneously due to hurricane damage with a 100-year return period and 6% could be destroyed in any 10-year period. Much of the hurricane risk to offshore wind turbines can be mitigated by designing turbines for higher maximum wind speeds, ensuring that turbine nacelles can turn quickly to track the wind direction even when grid power is lost, and building in areas with lower risk. 1. Iris Grossmann and M. Granger Morgan, "Tropical Cyclones, Climate Change, and Scientific Uncertainty: What do we know, what does it mean, and what should be done?," Climatic Change, 108, pp 543-579, 2011. 2. Carnegie Mellon Electricity Industry Center Working Paper CEIC-13-07, http://wpweb2.tepper.cmu.edu/electricity/papers/ceic-13-07.asp This work was supported in part by the EPA STAR fellowship program, a grant from the Alfred P. Sloan Foundation and EPRI to the Carnegie Mellon Electricity Industry Center, and by the Doris Duke Charitable Foundation, the R.K. Mellon Foundation and the Heinz Endowments for support of the RenewElec program at Carnegie Mellon University. This research was also supported in part by the Climate and

  12. Offshore Wind Market and Economic Analysis

    SciTech Connect

    Hamilton, Bruce Duncan

    2014-08-27

    This report is the third annual assessment of the U.S. offshore wind market. It includes the following major sections: Section 1: key data on developments in the offshore wind technology sector and the global development of offshore wind projects, with a particular focus on progress in the United States; Section 2: analysis of policy developments at the federal and state levels that have been effective in advancing offshore wind deployment in the United States; Section 3: analysis of actual and projected economic impact, including regional development and job creation; Section 4: analysis of developments in relevant sectors of the economy with the potential to affect offshore wind deployment in the United States

  13. Underbalanced drilling benefits now available offshore

    SciTech Connect

    Vozniak, J.P.; Cuthbertson, B.; Nessa, D.O.

    1997-05-01

    Offshore underbalanced drilling (UBD) is a reality. Applications in older, partially depleted fields and new fields are being considered. However, low productivity reservoirs and fields with sub normal pressures causing drilling problems are currently the main targets for offshore UBD. With proper planning and the correct technique, both jointed pipe and coiled tubing UBD drilling operations have been carried out offshore with success. The main concerns for offshore UBD have been altered drilling practices and surface production system operation. These issues have been examined and equipment has been designed and tested to address them. Environmental, safety and health issues are paramount and have been studied carefully. Detailed well planning, engineering, and flow modeling have proven critical for successful offshore UBD operations. Examples are given from oil and gas fields.

  14. Sharing a resource with randomly arriving foragers.

    PubMed

    Bernhard, Pierre; Hamelin, Frédéric

    2016-03-01

    We consider a problem of foraging where identical foragers, or predators, arrive as a stochastic Poisson process on the same patch of resource. We provide effective formulas for the expected resource intake of any of the agents, as a function of its rank, given their common functional response. We give a general theory, both in finite and infinite horizon, and show two examples of applications to harvesting a common under different assumptions about the resource dynamics and the functional response, and an example of application on a model that fits, among others, a problem of evolution of fungal plant parasites.

  15. A Comprehensive Structural Study of Offshore Wind Turbine Foundation and Non-Model Based Damage Detection using Effective Mass with Application to Small Components/ Cables and a Truss Wind Turbine Tower

    SciTech Connect

    Smith, Scott A.

    2016-10-01

    This research has two areas of focus. The first area is to investigate offshore wind turbine (OWT) designs, for use in the Maryland offshore wind area (MOWA), using intensive modeling techniques. The second focus area is to investigate a way to detect damage in wind turbine towers and small electrical components.

  16. Do invasive mussels restrict offshore phosphorus transport in Lake Huron?

    PubMed

    Cha, Yoonkyung; Stow, Craig A; Nalepa, Thomas F; Reckhow, Kenneth H

    2011-09-01

    Dreissenid mussels were first documented in the Laurentian Great Lakes in the late 1980s. Zebra mussels (Dreissena polymorpha) spread quickly into shallow, hard-substrate areas; quagga mussels (Dreissena rostriformis bugensis) spread more slowly and are currently colonizing deep, offshore areas. These mussels occur at high densities, filter large water volumes while feeding on suspended materials, and deposit particulate waste on the lake bottom. This filtering activity has been hypothesized to sequester tributary phosphorus in nearshore regions reducing offshore primary productivity. We used a mass balance model to estimate the phosphorus sedimentation rate in Saginaw Bay, a shallow embayment of Lake Huron, before and after the mussel invasion. Our results indicate that the proportion of tributary phosphorus retained in Saginaw Bay increased from approximately 46-70% when dreissenids appeared, reducing phosphorus export to the main body of Lake Huron. The combined effects of increased phosphorus retention and decreased phosphorus loading have caused an approximate 60% decrease in phosphorus export from Saginaw Bay to Lake Huron. Our results support the hypothesis that the ongoing decline of preyfish and secondary producers including diporeia (Diporeia spp.) in Lake Huron is a bottom-up phenomenon associated with decreased phosphorus availability in the offshore to support primary production.

  17. Foraging Behavior of Subantarctic Fur Seals Supports Efficiency of a Marine Reserve’s Design

    PubMed Central

    Kirkman, Stephen P.; Yemane, Dawit G.; Lamont, Tarron; Meÿer, Michael A.; Pistorius, Pierre A.

    2016-01-01

    Foraging behaviour of marine top predators is increasingly being used to identify areas of ecological importance. This is largely enabled by the ability of many such species to forage extensively in search of prey that is often concentrated in oceanographically productive areas. To identify important habitat in the Southern Indian Ocean within and around South Africa’s Prince Edward Islands’ Marine Protected Area (MPA), satellite transmitters were deployed on 12 lactating Subantarctic fur seals Arctocephalus tropicalis at Prince Edward Island (PEI) itself. Switching state space models were employed to correct ARGOS tracks and estimate behavioural states for locations along predicted tracks, namely travelling or area restricted search (ARS). A random forest model showed that distance from the study colony, longitude and distance from the Subantarctic Front were the most important predictors of suitable foraging habitat (inferred from ARS). Model-predicted suitable habitat occurred within the MPA in relatively close access to the colony during summer and autumn, but shifted northwards concurrently with frontal movements in winter and spring. The association of ARS with the MPA during summer-autumn was highly significant, highlighting the effectiveness of the recently declared reserve’s design for capturing suitable foraging habitat for this and probably other marine top predator species. PMID:27163373

  18. A properly adjusted forage harvester can save time and money

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A properly adjusted forage harvester can save fuel and increase the realizable milk per ton of your silage. This article details the adjustments necessary to minimize energy while maximizing productivity and forage quality....

  19. At-sea distribution and scale-dependent foraging behaviour of petrels and albatrosses: a comparative study.

    PubMed

    Pinaud, David; Weimerskirch, Henri

    2007-01-01

    1. In order to study and predict population distribution, it is crucial to identify and understand factors affecting individual movement decisions at different scales. Movements of foraging animals should be adjusted to the hierarchical spatial distribution of resources in the environment and this scale-dependent response to environmental heterogeneity should differ according to the forager's characteristics and exploited habitats. 2. Using First-Passage Time analysis, we studied scales of search effort and habitat used by individuals of seven sympatric Indian Ocean Procellariiform species fitted with satellite transmitters. We characterized their search effort distribution and examined whether species differ in scale-dependent adjustments of their movements according to the marine environment exploited. 3. All species and almost all individuals (91% of 122 individuals) exhibited an Area-Restricted Search (ARS) during foraging. At a regional scale (1000s km), foraging ranges showed a large spatial overlap between species. At a smaller scale (100s km, at which an increase in search effort occurred), a segregation in environmental characteristics of ARS zones (where search effort is high) was found between species. 4. Spatial scales at which individuals increased their search effort differed between species and also between exploited habitats, indicating a similar movement adjustment for predators foraging in the same habitat. ARS zones of the two populations of wandering albatross Diomedea exulans (Crozet and Kerguelen) were similar in their adjustments (i.e. same ARS scale) as well as in their environmental characteristics. These two populations showed a weak spatial overlap in their foraging distribution, with males foraging in more southerly waters than females in both populations. 5. This study demonstrates that predators of several species adjust their foraging behaviour to the heterogeneous environment and these scale-dependent movement adjustments depend on

  20. Genotype-environment interaction expressed in the foraging behaviour of dogwhelks, Nucella lapillus (L.), under simulated environmental hazard

    PubMed Central

    Hughes, R. N.; Taylor, M. J.

    1997-01-01

    The foraging behaviour of sub-adult Nucella lapillus originating from different field populations, was monitored for ten alternating, biweekly, periods of calm and wave action simulated in a tidal aquarium. Because the dogwhelks were reared under standard laboratory conditions, any behavioural differences among the experimental populations could reasonably be inferred to be linked to some genetically based mechanism. In order to forage, the dogwhelks had to leave a refugium, traverse empty 'habitat' and enter a patch of mussels serving as prey. Wave action markedly depressed foraging activity, increased foraging latency and lowered the patch-residence-time index. Dogwhelks derived from populations naturally occurring on shores exposed to wave action reduced their foraging activity less strongly than those derived from sheltered-shore populations, but geographical origin (Plymouth or Anglesey) had no significant influence on foraging behaviour. A simple interpretation was offered, linking the differential behavioural response to habitat-specific shell morphology, known to be heritable. According to this interpretation, all dogwhelks react similarly to the drag forces generated by wave action, but the relatively shorter-spired shells of exposed-shore dogwhelks cause weaker resultant forces than the taller-spired shells of sheltered-shore individuals. Consequently, exposed-shore dogwhelks tolerate higher levels of wave action than sheltered-shore morphs before suppressing their foraging behaviour. As exposed-shore dogwhelks have greater tenacity associated with relatively larger pedal area, the increased tolerance of wave action extends opportunities for foraging without incurring extra risk of dislodgement. The sheltered-shore morphology, which imparts greater resistance to desiccation, coincidentally increases drag and so makes dogwhelks more likely to seek refuge during occasional periods of heavy wave action. Exposed- and sheltered-shore morphologies therefore

  1. Evaluation and characterization of forage Sorghum as feedstock for fermentable sugar production.

    PubMed

    Corredor, D Y; Salazar, J M; Hohn, K L; Bean, S; Bean, B; Wang, D

    2009-07-01

    Sorghum is a tropical grass grown primarily in semiarid and drier parts of the world, especially areas too dry for corn. Sorghum production also leaves about 58 million tons of by-products composed mainly of cellulose, hemicellulose, and lignin. The low lignin content of some forage sorghums such as brown midrib makes them more digestible for ethanol production. Successful use of biomass for biofuel production depends on not only pretreatment methods and efficient processing conditions but also physical and chemical properties of the biomass. In this study, four varieties of forage sorghum (stems and leaves) were characterized and evaluated as feedstock for fermentable sugar production. Fourier transform infrared spectroscopy and X-ray diffraction were used to determine changes in structure and chemical composition of forage sorghum before and after pretreatment and the enzymatic hydrolysis process. Forage sorghums with a low syringyl/guaiacyl ratio in their lignin structure were easy to hydrolyze after pretreatment despite the initial lignin content. Enzymatic hydrolysis was also more effective for forage sorghums with a low crystallinity index and easily transformed crystalline cellulose to amorphous cellulose, despite initial cellulose content. Up to 72% hexose yield and 94% pentose yield were obtained using modified steam explosion with 2% sulfuric acid at 140 degrees C for 30 min and enzymatic hydrolysis with cellulase (15 filter per unit (FPU)/g cellulose) and beta-glucosidase (50 cellobiose units (CBU)/g cellulose).

  2. Effects of Liming on Forage Availability and Nutrient Content in a Forest Impacted by Acid Rain

    PubMed Central

    Pabian, Sarah E.; Ermer, Nathan M.; Tzilkowski, Walter M.; Brittingham, Margaret C.

    2012-01-01

    Acidic deposition and subsequent forest soil acidification and nutrient depletion can affect negatively the growth, health and nutrient content of vegetation, potentially limiting the availability and nutrient content of forage for white-tailed deer (Odocoileus virginianus) and other forest herbivores. Liming is a mitigation technique that can be used to restore forest health in acidified areas, but little is known about how it affects the growth or nutrient content of deer forage. We examined the effects of dolomitic limestone application on the growth and chemical composition of understory plants in an acidified forest in central Pennsylvania, with a focus on vegetative groups included as white-tailed deer forage. We used a Before-After-Control-Impact study design with observations 1 year before liming and up to 5 years post-liming on 2 treated and 2 untreated 100-ha sites. Before liming, forage availability and several nutrients were below levels considered optimal for white-tailed deer, and many vegetative characteristics were related to soil chemistry. We observed a positive effect of liming on forb biomass, with a 2.7 fold increase on limed sites, but no biomass response in other vegetation groups. We observed positive effects of liming on calcium and magnesium content and negative effects on aluminum and manganese content of several plant groups. Responses to liming by forbs and plant nutrients show promise for improving vegetation health and forage quality and quantity for deer. PMID:22761890

  3. Effects of liming on forage availability and nutrient content in a forest impacted by acid rain.

    PubMed

    Pabian, Sarah E; Ermer, Nathan M; Tzilkowski, Walter M; Brittingham, Margaret C

    2012-01-01

    Acidic deposition and subsequent forest soil acidification and nutrient depletion can affect negatively the growth, health and nutrient content of vegetation, potentially limiting the availability and nutrient content of forage for white-tailed deer (Odocoileus virginianus) and other forest herbivores. Liming is a mitigation technique that can be used to restore forest health in acidified areas, but little is known about how it affects the growth or nutrient content of deer forage. We examined the effects of dolomitic limestone application on the growth and chemical composition of understory plants in an acidified forest in central Pennsylvania, with a focus on vegetative groups included as white-tailed deer forage. We used a Before-After-Control-Impact study design with observations 1 year before liming and up to 5 years post-liming on 2 treated and 2 untreated 100-ha sites. Before liming, forage availability and several nutrients were below levels considered optimal for white-tailed deer, and many vegetative characteristics were related to soil chemistry. We observed a positive effect of liming on forb biomass, with a 2.7 fold increase on limed sites, but no biomass response in other vegetation groups. We observed positive effects of liming on calcium and magnesium content and negative effects on aluminum and manganese content of several plant groups. Responses to liming by forbs and plant nutrients show promise for improving vegetation health and forage quality and quantity for deer.

  4. Ecomorphology of eye shape and retinal topography in waterfowl (Aves: Anseriformes: Anatidae) with different foraging modes.

    PubMed

    Lisney, Thomas J; Stecyk, Karyn; Kolominsky, Jeffrey; Schmidt, Brian K; Corfield, Jeremy R; Iwaniuk, Andrew N; Wylie, Douglas R

    2013-05-01

    Despite the large body of literature on ecomorphological adaptations to foraging in waterfowl, little attention has been paid to their sensory systems, especially vision. Here, we compare eye shape and retinal topography across 12 species representing 4 different foraging modes. Eye shape was significantly different among foraging modes, with diving and pursuit-diving species having relatively smaller corneal diameters compared to non-diving species. This may be associated with differences in ambient light intensity while foraging or an ability to tightly constrict the pupil in divers in order to facilitate underwater vision. Retinal topography was similar across all species, consisting of an oblique visual streak, a central area of peak cell density, and no discernible fovea. Because the bill faces downwards when the head is held in the normal posture in waterfowl, the visual streak will be held horizontally, allowing the horizon to be sampled with higher visual acuity. Estimates of spatial resolving power were similar among species with only the Canada goose having a higher spatial resolution. Overall, we found no evidence of ecomorphological adaptations to different foraging modes in the retinal ganglion cell layer in waterfowl. Rather, retinal topography in these birds seems to reflect the 'openness' of their habitats.

  5. Drift algae reduce foraging efficiency of juvenile flatfish

    NASA Astrophysics Data System (ADS)

    Nordström, Marie; Booth, Dale M.

    2007-11-01

    Although flatfish species utilise a wide range of habitats as adults, several species are confined to a very limited habitat as juveniles. Recruitment levels are dependent on the quality and quantity of these nursery areas and changes therein. In the Baltic Sea, these shallow environments are often subject to influxes of drifting macroalgae, which add structure to otherwise bare sandy substrate. Structure, such as vegetation, alters predator-prey interactions of a wide range of fauna and in an array of marine, freshwater, and terrestrial systems. The aim of our study was to assess the inhibition potential of drifting macroalgae on the foraging efficiency of juvenile flatfish (young of the year Scophthalmus maximus L., young of the year- and group 1 + Platichthys flesus L.) through a series of microcosm experiments. Our results show that foraging success is restricted by drift algae as predation efficiency of all predator species and size classes was negatively affected by the presence of macroalgae. Overall, there was a reduction in predation success by 80 ± 12% due to structural effects and/or the induced changes in water chemistry associated with the algae. Flatfish depend on shallow sandy areas as feeding and nursery grounds during their juvenile stage and frequently occurring macroalgal assemblages drastically change the features of the otherwise bare substrate, setting the stage for small-scale, localised processes potentially affecting population dynamics.

  6. Foraging theory upscaled: the behavioural ecology of herbivore movement

    PubMed Central

    Owen-Smith, N.; Fryxell, J. M.; Merrill, E. H.

    2010-01-01

    We outline how principles of optimal foraging developed for diet and food patch selection might be applied to movement behaviour expressed over larger spatial and temporal scales. Our focus is on large mammalian herbivores, capable of carrying global positioning system (GPS) collars operating through the seasonal cycle and dependent on vegetation resources that are fixed in space but seasonally variable in availability and nutritional value. The concept of intermittent movement leads to the recognition of distinct movement modes over a hierarchy of spatio-temporal scales. Over larger scales, periods with relatively low displacement may indicate settlement within foraging areas, habitat units or seasonal ranges. Directed movements connect these patches or places used for other activities. Selection is expressed by switches in movement mode and the intensity of utilization by the settlement period relative to the area covered. The type of benefit obtained during settlement periods may be inferred from movement patterns, local environmental features, or the diel activity schedule. Rates of movement indicate changing costs in time and energy over the seasonal cycle, between years and among regions. GPS telemetry potentially enables large-scale movement responses to changing environmental conditions to be linked to population performance. PMID:20566503

  7. Uninformed sacrifice: Evidence against long-range alarm transmission in foraging ants exposed to localized abduction

    NASA Astrophysics Data System (ADS)

    Tejera, F.; Reyes, A.; Altshuler, E.

    2016-07-01

    It is well established that danger information can be transmitted by ants through relatively small distances, provoking either a state of alarm when they move away from potentially dangerous stimulus, or charge toward it aggressively. There is almost no knowledge if danger information can be transmitted along large distances. In this paper, we abduct leaf cutting ants of the species Atta insularis while they forage in their natural environment at a certain point of the foraging line, so ants make a "U" turn to escape from the danger zone and go back to the nest. Our results strongly suggest that those ants do not transmit "danger information" to other nestmates marching towards the abduction area. The individualistic behavior of the ants returning from the danger zone results in a depression of the foraging activity due to the systematic sacrifice of non-informed individuals.

  8. Monitoring California's forage resource using ERTS-1 and supporting aircraft data

    NASA Technical Reports Server (NTRS)

    Carneggie, D. M.; Degloria, S. D.

    1973-01-01

    NASA's Earth Resource Technology Satellite (ERTS-1) launched July 23, 1972, offers for the first time the unique capabilities for regional monitoring of forage plant conditions. The repetitive coverage every 18 days, the synoptic view and the real-time recovery of the imagery for immediate analysis, combine to make the ERTS satellite a valuable tool for improving the evaluation of our rangeland resources. Studies presently underway at the University of California, Berkeley (sponsored jointly by NASA and the Bureau of Land Management), seek to determine if imagery obtained from high altitude aircraft and spacecraft (ERTS) can provide: (1) a means for monitoring the growth and development of annual and perennial range plants in California, and for determining the time and the rate of initial plant growth (germination) and terminal plant growth (maturation and senescence); (2) a means for determining or predicting the relative amount of forage that is produced; and (3) a means for mapping rangeland areas having different forage producing capabilities.

  9. Littoral foraging by red phalaropes during spring in the northern Bering Sea

    USGS Publications Warehouse

    Haney, J. Chris; Stone, Amy E.

    1988-01-01

    Phalaropes demonstrate considerable plasticity in their choice of foraging habitats. The Red Phalarope (Phalaropus fulicaria) alternates use of pelagic environments in winter and migration (Taning 1933, Stanford 1953, Briggs et al 1984) with wet tundra habitats during the breeding season (Kistchinski 1975, Mayfield 1979, Ridley 1980). Foods available and taken in littoral zones of the Arctic Ocean in fall have been identified (Conners and Risebrough 1978, Johnson and Richardson 1980), but otherwise little attention has been devoted to the transition between the marine and terrestrial periods of the Red Phalarope’s life history. We report phalarope use of littoral areas during spring in the northern Bering Sea and Kongkok Bay, St. Lawrence Island, Alaska. In addition, we describe phalarope foraging tactics and foods available in the sur zone, emphasizing this form of littoral foraging as an opportunistic and facultative feeding strategy.

  10. Foraging flights of the white-tailed tropicbird (Phaethon lepturus): Radiotracking and doubly-labelled water

    USGS Publications Warehouse

    Pennycuick, C.J.; Shaffner, F.C.; Fuller, M.R.; Obrecht, H.H.; Sternberg, L.

    1990-01-01

    Radiotracking transmitters were fitted to White-tailed Tropicbirds nesting at Culebra, Puerto Rico. Foragers were located by light aircraft out to 89 km SSW of the nesting colony, over a deep-water foraging area south of Vieques Island, Puerto Rico and west of St Croix, U. S. Virgin Islands. Two birds were followed out to 176 km NNW from the colony, over the Puerto Rico Trench, but these did not subsequently return. Foragers carrying radio transmitters performed similarly to those without, in terms of duration of absence from the colony, and mass of food brought for the chick. However, measuremetns of energy consumption by the doubly labelled water method indicated that birds with transmitters consumed significantly more energy than those without.

  11. Exploration and development offshore southern Vietnam

    SciTech Connect

    Ferguson, A.M. )

    1996-01-01

    In Vietnam, the major focus of the oil and gas industry is on the Nam Con Son and Cuu Long Basins in the southern offshore area. Major licensing first occurred here in the early 1970s. Some exploration was also undertaken by foreign companies in the early 1980s. In 1981, the Soviet Union undertook to assist Vietnam with the development of oil and gas. Vietsovpetro, a joint venture between the then Soviet Oil and Gas Ministry and the Vietnam Oil and Gas Corporation was formed. Most of Vietsovpetro's efforts have been to develop the Bach Ho field in the Cuu Long Basin. This now produces [approximately]130000 bopd. The most recent large scale licensing round occurred in 1992, and, at present, there are over thirty foreign companies active in these Basins' blocks . The first phase of exploration is ending and successes in the Nam Con Son Basin include the BP-led Lan Tay/Lan Do gas discoveries and Pedco's gas discoveries. Mitsubishi's and Petronas' oil discoveries in the Cuu Long Basin have attracted much attention also. The Dai Hung oil field (BHP-operated) has been producing since late 1994. Certain blocks are being appraised, and exploration work is also continuing. Areas of the Cuu Long Basin that were part of Vietsovpetro's acreage, but which may soon be re-licensed, have generated keen interest. The presence of an active upstream industry - exploring, appraising, developing and producing - indicates the emergence of Vietnam as an important East Asian oil and gas player.

  12. Geologic framework of the offshore region adjacent to Delaware

    USGS Publications Warehouse

    Benson, R.N.; Roberts, J.H.

    1989-01-01

    Several multichannel, common depth point (CDP) seismic reflection profiles concentrated in the area of the entrance to Delaware Bay provide a tie between the known onshore geology of the Coastal Plain of Delaware and the offshore geology of the Baltimore Canyon Trough. The data provide a basis for understanding the geologic framework and petroleum resource potential of the area immediately offshore Delaware. Our research has focused on buried early Mesozoic rift basins and their geologic history. Assuming that the buried basins are analogous to the exposed Newark Supergroup basins of Late Triassic-Early Jurassic age, the most likely possibility for occurrence of hydrocarbon source beds in the area of the landward margin of the Baltimore Canyon Trough is presumed to be lacustrine, organic-rich shales probably present in the basins. Although buried basins mapped offshore Delaware are within reach of drilling, no holes have been drilled to date; therefore, direct knowledge of source, reservoir, and sealing beds is absent. Buried rift basins offshore Delaware show axial trends ranging from NW-SE to NNE-SSW. Seismic reflection profiles are too widely spaced to delineate basin boundaries accurately. Isopleths of two-way travel time representing basin fill suggest that, structurally, the basins are grabens and half-grabens. As shown on seismic reflection profiles, bounding faults of the basins intersect or merge with low-angle fault surfaces that cut the pre-Mesozoic basement. The rift basins appear to have formed by Mesozoic extension that resulted in reverse motion on reactivated basement thrust faults that originated from compressional tectonics during the Paleozoic. Computer-plotted structure contour maps derived from analysis of seismic reflection profiles provide information on the burial history of the rift basins. The postrift unconformity bevels the rift basins and, in the offshore area mapped, ranges from 2000 to 12,000 m below present sea level. The oldest

  13. Effects of offshore oil drilling on Philippine reef corals.

    USGS Publications Warehouse

    Hudson, J.H.; Shinn, E.A.; Robbin, D.M.

    1982-01-01

    An offshore drilling site in an area of extensive live-coral bottom off NW Palawan Island, Philippines, was examined 15 months after well completion. Porites lutea growth rates showed that little suppression of head coral growth could be attributed to drilling. Diver observation, however, together with analysis of sampling transect photomosaics, revealed 70-90% reduction in foliose, branching, and plate-like corals in an iron-stained area that extended out from the wellheads in a 115 X 85-m ellipse.-from Authors

  14. Foraging habitats of southern elephant seals, Mirounga leonina, from the Northern Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Muelbert, Monica M. C.; de Souza, Ronald B.; Lewis, Mirtha N.; Hindell, Mark A.

    2013-04-01

    Elephant Island (EI) is uniquely placed to provide southern elephant seals (SES) breeding there with potential access to foraging grounds in the Weddell Sea, the frontal zones of the South Atlantic Ocean, the Patagonian shelf and the Western Antarctic Peninsula (WAP). Quantifying where seals from EI forage therefore provides insights into the types of important habitats available, and which are of particular importance to elephant seals. Twenty nine SES (5 sub-adult males—SAM and 24 adult females—AF) were equipped with SMRU CTD-SLDRs during the post-breeding (PB 2008, 2009) and post-moulting (PM 2007, 2008, 2009, 2010) trips to sea. There were striking intra-annual and inter-sex differences in foraging areas, with most of the PB females remaining within 150 km of EI. One PB AF travelled down the WAP as did 16 out of the 20 PM females and foraged near the winter ice-edge. Most PM sub-adult males remained close to EI, in areas similar to those used by adult females several months earlier, although one SAM spent the early part of the winter foraging on the Patagonian Shelf. The waters of the Northern Antarctic Peninsula (NAP) contain abundant resources to support the majority of the Islands' SES for the summer and early winter, such that the animals from this population have shorter migrations than those from most other populations. Sub-adult males and PB females are certainly taking advantage of these resources. However, PM females did not remain there over the winter months, instead they used the same waters at the ice-edge in the southern WAP that females from both King George Island and South Georgia used. Females made more benthic dives than sub-adult males—again this contrasts with other sites where SAMs do more benthic diving. Unlike most other populations studied to date EI is a relatively southerly breeding colony located on the Antarctic continental shelf. EI seals are using shelf habitats more than other SES populations but some individuals still

  15. Breeding success of a marine central place forager in the context of climate change: A modeling approach

    PubMed Central

    Massardier-Galatà, Lauriane; Morinay, Jennifer; Bailleul, Frédéric; Wajnberg, Eric; Guinet, Christophe; Coquillard, Patrick

    2017-01-01

    In response to climate warming, a southward shift in productive frontal systems serving as the main foraging sites for many top predator species is likely to occur in Subantarctic areas. Central place foragers, such as seabirds and pinnipeds, are thus likely to cope with an increase in the distance between foraging locations and their land-based breeding colonies. Understanding how central place foragers should modify their foraging behavior in response to changes in prey accessibility appears crucial. A spatially explicit individual-based simulation model (Marine Central Place Forager Simulator (MarCPFS)), including bio-energetic components, was built to evaluate effects of possible changes in prey resources accessibility on individual performances and breeding success. The study was calibrated on a particular example: the Antarctic fur seal (Arctocephalus gazella), which alternates between oceanic areas in which females feed and the land-based colony in which they suckle their young over a 120 days rearing period. Our model shows the importance of the distance covered to feed and prey aggregation which appeared to be key factors to which animals are highly sensitive. Memorization and learning abilities also appear to be essential breeding success traits. Females were found to be most successful for intermediate levels of prey aggregation and short distance to the resource, resulting in optimal female body length. Increased distance to resources due to climate warming should hinder pups’ growth and survival while female body length should increase. PMID:28355282

  16. Breeding success of a marine central place forager in the context of climate change: A modeling approach.

    PubMed

    Massardier-Galatà, Lauriane; Morinay, Jennifer; Bailleul, Frédéric; Wajnberg, Eric; Guinet, Christophe; Coquillard, Patrick

    2017-01-01

    In response to climate warming, a southward shift in productive frontal systems serving as the main foraging sites for many top predator species is likely to occur in Subantarctic areas. Central place foragers, such as seabirds and pinnipeds, are thus likely to cope with an increase in the distance between foraging locations and their land-based breeding colonies. Understanding how central place foragers should modify their foraging behavior in response to changes in prey accessibility appears crucial. A spatially explicit individual-based simulation model (Marine Central Place Forager Simulator (MarCPFS)), including bio-energetic components, was built to evaluate effects of possible changes in prey resources accessibility on individual performances and breeding success. The study was calibrated on a particular example: the Antarctic fur seal (Arctocephalus gazella), which alternates between oceanic areas in which females feed and the land-based colony in which they suckle their young over a 120 days rearing period. Our model shows the importance of the distance covered to feed and prey aggregation which appeared to be key factors to which animals are highly sensitive. Memorization and learning abilities also appear to be essential breeding success traits. Females were found to be most successful for intermediate levels of prey aggregation and short distance to the resource, resulting in optimal female body length. Increased distance to resources due to climate warming should hinder pups' growth and survival while female body length should increase.

  17. Effects of rain damage on wilting forages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the most common problems faced by hay or silage producers is how to manage production schedules around unfavorable weather. Inevitably, some wilting forage crops are damaged by unexpected rainfall events each year, and producers often inquire about the effects of unexpected rain damage, and w...

  18. The Kanizsa triangle illusion in foraging ants.

    PubMed

    Sakiyama, Tomoko; Gunji, Yukio-Pegio

    2016-01-01

    The Kanizsa triangle, wherein three Pac-Man configurations symmetrically face inwards, is a well-known illusion. By exposing foraging ants (Lasius niger) to Kanizsa-shaped honeydew solutions, we studied the origin of this illusion. More specifically, we examined whether foraging ants showed different movement reactions to local honeydew patterns formed by nestmates. This novel phenomenon could serve as an abstract model of the Kanizsa triangle illusion under the assumption that such an illusion could arise through the sum of each agent's limited global cognitions, because each agent could not perceive the entire subjective contours. Even a subjective consciousness consists of some parts which have no identical perception and could be an illusion. We succeeded in inducing foragers to move along the sides of a Kanizsa triangle when Pac-Man-shaped inducers were introduced. Furthermore, foragers appeared to form Y-shaped trajectories when dot-shaped or inverse Kanizsa inducers were used. Based on our findings, we propose an agent-based ant model that compares modelled behaviour with experimental phenomena. Our abstract model could be used to explain such cognitive phenomena for bottom-up processes, because ants cannot perceive the given subjective contours, instead simply move along the edges.

  19. The Dynamics of Infant Visual Foraging

    ERIC Educational Resources Information Center

    Robertson, Steven S.; Guckenheimer, John; Masnick, Amy M.; Bacher, Leigh F.

    2004-01-01

    Human infants actively forage for visual information from the moment of birth onward. Although we know a great deal about how stimulus characteristics influence looking behavior in the first few postnatal weeks, we know much less about the intrinsic dynamics of the behavior. Here we show that a simple stochastic dynamical system acts…

  20. Investigating Optimal Foraging Theory in the Laboratory

    ERIC Educational Resources Information Center

    Harden, Siegfried; Grilliot, Matthew E.

    2014-01-01

    Optimal foraging theory is a principle that is often presented in the community ecology section of biology textbooks, but also can be demonstrated in the laboratory. We introduce a lab activity that uses an interactive strategy to teach high school and/or college students about this ecological concept. The activity is ideal because it engages…

  1. Balancing organization and flexibility in foraging dynamics.

    PubMed

    Tabone, Michaelangelo; Ermentrout, Bard; Doiron, Brent

    2010-10-07

    Proper pattern organization and reorganization are central problems facing many biological networks which thrive in fluctuating environments. However, in many cases the mechanisms that organize system activity oppose those that support behavioral flexibility. Thus, a balance between pattern organization and pattern flexibility is critically important for overall biological fitness. We study this balance in the foraging strategies of ant colonies exploiting food in dynamic environments. We present discrete time and space simulations of colony activity that uses a pheromone-based recruitment strategy biasing foraging towards a food source. After food relocation, the pheromone must evaporate sufficiently before foraging can shift colony attention to a new food source. The amount of food consumed within the dynamic environment depends non-monotonically on the pheromone evaporation time constant-with maximal consumption occurring at a time constant which balances trail formation and trail flexibility. A deterministic, 'mean field' model of pheromone and foragers on trails mimics our colony simulations. This reduced framework captures the essence of the flexibility-organization balance, and relates optimal pheromone evaporation to the timescale of the dynamic environment. We expect that the principles exposed in our study will generalize and motivate novel analysis across a broad range systems biology.

  2. Forage harvest representation in RUSLE2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Revised Universal Soil Loss Equation (RUSLE and RUSLE2) has long been used by USDA and others for management planning based on soil erosion and sediment delivery estimates. It has worked well for normal annual agronomic crops, but proved to be awkward for forage crops. This is partly because RU...

  3. Improving forage quality using seedhead management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Controlling seedhead emergence in perennial grass pastures can extend vegetative growth and high leaf:stem ratios to avoid declines in forage quality during the reproductive development of grasses. There are various management tools for controlling the emergence of seedheads. Pastures can be mowed...

  4. Animal Methods for Evaluating Forage Quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Numerous methods are available that employ animals in the assessment of forage quality. Some of these procedures provide information needed to address very specific goals (e.g., monitoring protein adequacy), some serve as useful contributors to the efforts to accurately predict nutritive value, wher...

  5. Rangeland and warm-season forage grasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Livestock ranchers depend on grassland grazing for a substantial part of their livestock management systems. Grassland forages make up to 85% of the feed supply for ruminant animal products, especially in warm climates. Grass breeding in general creates some unique breeding challenges ranging from...

  6. Scholarly Foraging and Network Discovery Tools.

    ERIC Educational Resources Information Center

    Cronin, Blaise; Hert, Carol A.

    1995-01-01

    Parallels between subsistence foraging and scholarly information seeking are described in the context of the World Wide Web. Suggests that the prevailing information retrieval paradigm does not capture the complex of behavior and stimuli that drives scholars' quests for new ideas and insights. Research questions are suggested by extended use of…

  7. The offshore petroleum industry: The formative years, 1945-1962

    NASA Astrophysics Data System (ADS)

    Kreidler, Tai Deckner

    1997-12-01

    a response to increasing work done for the offshore industry. Academic areas that developed included oceanography, physical oceanography, marine biology, marine geology, meteorology, and weather forecasting, During the formative era that ended in the late 1950s the industry had formed its technological and economic foundation in the Gulf, and stood poised to seize the initiative in the North Sea, the Middle East, the Far East, and Indonesia.

  8. A Real-Time Offshore Weather Risk Advisory System

    NASA Astrophysics Data System (ADS)

    Jolivet, Samuel; Zemskyy, Pavlo; Mynampati, Kalyan; Babovic, Vladan

    2015-04-01

    Offshore oil and gas operations in South East Asia periodically face extended downtime due to unpredictable weather conditions, including squalls that are accompanied by strong winds, thunder, and heavy rains. This downtime results in financial losses. Hence, a real time weather risk advisory system is developed to provide the offshore Oil and Gas (O&G) industry specific weather warnings in support of safety and environment security. This system provides safe operating windows based on sensitivity of offshore operations to sea state. Information products for safety and security include area of squall occurrence for the next 24 hours, time before squall strike, and heavy sea state warning for the next 3, 6, 12 & 24 hours. These are predicted using radar now-cast, high resolution Numerical Weather Prediction (NWP) and Data Assimilation (DA). Radar based now-casting leverages the radar data to produce short term (up to 3 hours) predictions of severe weather events including squalls/thunderstorms. A sea state approximation is provided through developing a translational model based on these predictions to risk rank the sensitivity of operations. A high resolution Weather Research and Forecasting (WRF, an open source NWP model) is developed for offshore Brunei, Malaysia and the Philippines. This high resolution model is optimized and validated against the adaptation of temperate to tropical met-ocean parameterization. This locally specific parameters are calibrated against federated data to achieve a 24 hour forecast of high resolution Convective Available Potential Energy (CAPE). CAPE is being used as a proxy for the risk of squall occurrence. Spectral decomposition is used to blend the outputs of the now-cast and the forecast in order to assimilate near real time weather observations as an implementation of the integration of data sources. This system uses the now-cast for the first 3 hours and then the forecast prediction horizons of 3, 6, 12 & 24 hours. The output is

  9. NREL Offshore Balance-of-System Model

    SciTech Connect

    Maness, Michael; Maples, Benjamin; Smith, Aaron

    2017-01-01

    The U.S. Department of Energy (DOE) has investigated the potential for 20% of nationwide electricity demand to be generated from wind by 2030 and, more recently, 35% by 2050. Achieving this level of wind power generation may require the development and deployment of offshore wind technologies. DOE (2008) has indicated that reaching these 2030 and 2050 scenarios could result in approximately 10% and 20%, respectively, of wind energy generation to come from offshore resources. By the end of 2013, 6.5 gigawatts of offshore wind were installed globally. The first U.S. project, the Block Island Wind Farm off the coast of Rhode Island, has recently begun operations. One of the major reasons that offshore wind development in the United States is lagging behind global trends is the high capital expenditures required. An understanding of the costs and associated drivers of building a commercial-scale offshore wind plant in the United States will inform future research and help U.S. investors feel more confident in offshore wind development. In an effort to explain these costs, the National Renewable Energy Laboratory has developed the Offshore Balance-of-System model.

  10. Offshore Fish Community: Ecological Interactions | Science ...

    EPA Pesticide Factsheets

    The offshore (>80 m) fish community of Lake Superior is made up of predominately native species. The most prominent species are deepwater sculpin, kiyi, cisco, siscowet lake trout, burbot, and the exotic sea lamprey. Bloater and shortjaw cisco are also found in the offshore zone. Bloater is abundant in the offshore zone but appears restricted to depths shallower than 150 m (Selgeby and Hoff 1996; Stockwell et al. 2010), although it occuppied greater depths several decades ago (Dryer 1966; Peck 1977). Shortjaw is relatively rare in the offshore zone (Hoff and Todd 2004; Gorman and Hoff 2009; Gorman and Todd 2007). Lake whitefish is also known to frequent bathymetric depths >100 m (Yule et al. 2008b). In this chapter, we develop a conceptual model of the offshore food web based on data collected during 2001-2005 and on inferences from species interactions known for the nearshore fish community. We then develop a framework for examination of energy and nutrient movements within the pelagic and benthic habitats of the offshore zone and across the offshore and nearshore zones. To document research results.

  11. Shallow groundwater quality on dairy farms with irrigated forage crops

    NASA Astrophysics Data System (ADS)

    Harter, Thomas; Davis, Harley; Mathews, Marsha C.; Meyer, Roland D.

    2002-04-01

    California's dairies are the largest confined animal industry in the state. A major portion of these dairies, which have an average herd size of nearly 1000 animal units, are located in low-relief valleys and basins. Large amounts of liquid manure are generated and stored in these dairies. In the semi-arid climate, liquid manure is frequently applied via flood or furrow irrigation to forage crops that are grown almost year-round. Little is known about the impact of manure management practices on water quality of the extensive alluvial aquifers underlying these basins. The objective of this work is to assess nitrate and salt leaching to shallow groundwater in a relatively vulnerable hydrogeologic region and to quantify the impact from individual sources on dairies. The complex array of potential point and nonpoint sources was divided into three major source areas representing farm management units: (1) manure water lagoons (ponds); (2) feedlot or exercise yard, dry manure, and feed storage areas (corrals); and (3) manure irrigated forage fields (fields). An extensive shallow groundwater-monitoring network (44 wells) was installed in five representative dairy operations in the northeastern San Joaquin Valley, CA. Water quality (electrical conductivity, nitrate-nitrogen, total Kjehldahl nitrogen) was observed over a 4-year period. Nitrate-N, reduced nitrogen and electrical conductivity (EC, salinity) were subject to large spatial and temporal variability. The range of observed nitrate-N and salinity levels was similar on all five dairies. Average shallow groundwater nitrate-N concentrations within the dairies were 64 mg/l compared to 24 mg/l in shallow wells immediately upgradient of these dairies. Average EC levels were 1.9 mS/cm within the dairies and 0.8 mS/cm immediately upgradient. Within the dairies, nitrate-N levels did not significantly vary across dairy management units. However, EC levels were significantly higher in corral and pond