Occurrence, distribution and transport of pesticides into the Salton Sea Basin, California, 2001-2002

USGS Publications Warehouse

LeBlanc, L.A.; Kuivila, K.M.

2008-01-01

The Salton Sea is a hypersaline lake located in southeastern California. Concerns over the ecological impacts of sediment quality and potential human exposure to dust emissions from exposed lakebed sediments resulting from anticipated shrinking of shoreline led to a study of pesticide distribution and transport within the Salton Sea Basin, California, in 2001-2002. Three sampling stations-upriver, river mouth, and offshore-were established along each of the three major rivers that discharge into the Salton Sea. Large-volume water samples were collected for analysis of pesticides in water and suspended sediments at the nine sampling stations. Samples of the bottom sediment were also collected at each site for pesticide analysis. Sampling occurred in October 2001, March-April 2002, and October 2002, coinciding with the regional fall and spring peaks in pesticide use in the heavily agricultural watershed. Fourteen current-use pesticides were detected in water and the majority of dissolved concentrations ranged from the limits of detection to 151 ng/l. Diazinon, EPTC and malathion were detected at much higher concentrations (940-3,830 ng/l) at the New and Alamo River upriver and near-shore stations. Concentrations of carbaryl, dacthal, diazinon, and EPTC were higher in the two fall sampling periods, whereas concentrations of atrazine, carbofuran, and trifluralin were higher during the spring, which matched seasonal use patterns of these pesticides. Current-use pesticides were also detected on suspended and bed sediments in concentrations ranging from detection limits to 106 ng/g. Chlorpyrifos, dacthal, EPTC, trifluralin, and DDE were the most frequently detected pesticides on sediments from all three rivers. The number of detections and concentrations of suspended sediment-associated pesticides were often similar for the river upriver and near-shore sites, consistent with downstream transport of pesticides via suspended sediment. While detectable suspended sediment

Pleurochrysis pseudoroscoffensis (Prymnesiophyceae) blooms on the surface of the Salton Sea, California

USGS Publications Warehouse

Reifel, K.M.; McCoy, M.P.; Tiffany, M.A.; Rocke, T.E.; Trees, C.C.; Barlow, S.B.; Faulkner, D.J.; Hurlbert, S.H.

2001-01-01

Dense populations of the coccolithophore Pleurochrysis pseudoroscoffensis were found in surface films at several locations around the Salton Sea in Februarya??August, 1999. An unidentified coccolithophorid was also found in low densities in earlier studies of the lake (1955a??1956). To our knowledge, this is the first record of this widespread marine species in any lake. Samples taken from surface films typically contained high densities of one or two other phytoplankton species as well as high densities of the coccolithophore. Presence or absence of specific algal pigments was used to validate direct cell counts. In a preliminary screen using a brine shrimp lethality assay, samples showed moderate activity. Extracts were then submitted to a mouse bioassay, and no toxic activity was observed. These results indicate that blooms of P. pseudoroscoffensis are probably not toxic to vertebrates and do not contribute to the various mortality events of birds and fish that occur in the Salton Sea.

Pleurochrysis pseudoroscoffensis (Prymnesiophyceae) blooms on the surface of the Salton Sea, California

USGS Publications Warehouse

Reifel, K.M.; McCoy, M.P.; Tiffany, M.A.; Rocke, T.E.; Trees, C.C.; Barlow, S.B.; Faulkner, D.J.; Hurlbert, S.H.

2001-01-01

Dense populations of the coccolithophore Pleurochrysis pseudoroscoffensis were found in surface films at several locations around the Salton Sea in February-August, 1999. An unidentified coccolithophorid was also found in low densities in earlier studies of the lake (1955-1956). To our knowledge, this is the first record of this widespread marine species in any lake. Samples taken from surface films typically contained high densities of one or two other phytoplankton species as well as high densities of the coccolithophore. Presence or absence of specific algal pigments was used to validate direct cell counts. In a preliminary screen using a brine shrimp lethality assay, samples showed moderate activity. Extracts were then submitted to a mouse bioassay, and no toxic activity was observed. These results indicate that blooms of P. pseudoroscoffensis are probably not toxic to vertebrates and do not contribute to the various mortality events of birds and fish that occur in the Salton Sea.

Crustal and upper mantle velocity structure of the Salton Trough, southeast California

USGS Publications Warehouse

Parsons, T.; McCarthy, J.

1996-01-01

This paper presents data and modelling results from a crustal and upper mantle wide-angle seismic transect across the Salton Trough region in southeast California. The Salton Trough is a unique part of the Basin and Range province where mid-ocean ridge/transform spreading in the Gulf of California has evolved northward into the continent. In 1992, the U.S. Geological Survey (USGS) conducted the final leg of the Pacific to Arizona Crustal Experiment (PACE). Two perpendicular models of the crust and upper mantle were fit to wide-angle reflection and refraction travel times, seismic amplitudes, and Bouguer gravity anomalies. The first profile crossed the Salton Trough from the southwest to the northeast, and the second was a strike line that paralleled the Salton Sea along its western edge. We found thin crust (???21-22 km thick) beneath the axis of the Salton Trough (Imperial Valley) and locally thicker crust (???27 km) beneath the Chocolate Mountains to the northeast. We modelled a slight thinning of the crust further to the northeast beneath the Colorado River (???24 km) and subsequent thickening beneath the metamorphic core complex belt northeast of the Colorado River. There is a deep, apparently young basin (???5-6 km unmetamorphosed sediments) beneath the Imperial Valley and a shallower (???2-3 km) basin beneath the Colorado River. A regional 6.9-km/s layer (between ???15-km depth and the Moho) underlies the Salton Trough as well as the Chocolate Mountains where it pinches out at the Moho. This lower crustal layer is spatially associated with a low-velocity (7.6-7.7 km/s) upper mantle. We found that our crustal model is locally compatible with the previously suggested notion that the crust of the Salton Trough has formed almost entirely from magmatism in the lower crust and sedimentation in the upper crust. However, we observe an apparently magmatically emplaced lower crust to the northeast, outside of the Salton Trough, and propose that this layer in part

Response in the water quality of the Salton Sea, California, to changes in phosphorus loading: An empirical modeling approach

USGS Publications Warehouse

Robertson, Dale M.; Schladow, S.G.

2008-01-01

Salton Sea, California, like many other lakes, has become eutrophic because of excessive nutrient loading, primarily phosphorus (P). A Total Maximum Daily Load (TMDL) is being prepared for P to reduce the input of P to the Sea. In order to better understand how P-load reductions should affect the average annual water quality of this terminal saline lake, three different eutrophication programs (BATHTUB, WiLMS, and the Seepage Lake Model) were applied. After verifying that specific empirical models within these programs were applicable to this saline lake, each model was calibrated using water-quality and nutrient-loading data for 1999 and then used to simulate the effects of specific P-load reductions. Model simulations indicate that a 50% decrease in external P loading would decrease near-surface total phosphorus concentrations (TP) by 25-50%. Application of other empirical models demonstrated that this decrease in loading should decrease near-surface chlorophyll a concentrations (Chl a) by 17-63% and increase Secchi depths (SD) by 38-97%. The wide range in estimated responses in Chl a and SD were primarily caused by uncertainty in how non-algal turbidity would respond to P-load reductions. If only the models most applicable to the Salton Sea are considered, a 70-90% P-load reduction is required for the Sea to be classified as moderately eutrophic (trophic state index of 55). These models simulate steady-state conditions in the Sea; therefore, it is difficult to ascertain how long it would take for the simulated changes to occur after load reductions. ?? 2008 Springer Science+Business Media B.V.

Hydrogen sulfide production and volatilization in a polymictic eutrophic saline lake, Salton Sea, California.

PubMed

Reese, Brandi Kiel; Anderson, Michael A; Amrhein, Christopher

2008-11-15

The Salton Sea is a large shallow saline lake located in southern California that is noted for high sulfate concentrations, substantial algal productivity, and very warm water column temperatures. These conditions are well-suited for sulfide production, and sulfide has been implicated in summer fish kills, although no studies have been conducted to specifically understand hydrogen sulfide production and volatilization there. Despite polymictic mixing patterns and relatively short accumulation periods, the amount of sulfide produced is comparable to meromictic lakes. Sulfide levels in the Salton Sea reached concentrations of 1.2 mmol L(-1) of total free sulfide in the hypolimnion and 5.6 mmol L(-1) in the sediment pore water. Strong winds in late July mixed H2S into the surface water, where it depleted the entire water column of dissolved oxygen and reached a concentration of 0.1 mmol L(-1). Sulfide concentrations exceeded the toxicity threshold of tilapia (Oreochromis mossambicus) and combined with strong anoxia throughout the water column, resulted in a massive fish kill. The mixing of sulfide into the surface waters also increased atmospheric H2S concentrations, reaching 1.0 micromol m(-3). The flux of sulfide from the sediment into the water column was estimated to range from 2-3 mmol m(-2) day(-1) during the winter and up to 8 mmol m(-2) day(-1) during the summer. Application of the two-layer model for volatilization indicates that up to 19 mmol m(-2) day(-1) volatilized from the surface during the mixing event. We estimate that as much as 3400 Mg year(-1) or approximately 26% of sulfide that diffused into the water column from the deepest sediments may have been volatilized to the atmosphere.

Curie Depth Analysis of the Salton Sea Region, Southern California

NASA Astrophysics Data System (ADS)

Mickus, Kevin; Hussein, Musa

2016-02-01

Aeromagnetic data were analyzed to determine the bottom of magnetic bodies that might be related to the Curie point depth (CPD) by 2D spectral and 3D inversion methods within the Salton Trough and the surrounding region in southern California. The bottom of the magnetic bodies for 55 × 55 km windows varied in depth between 11 and 23 km in depth using 2D spectral methods. Since the 55 × 55 km square window may include both shallow and deep source, a 3D inversion method was used to provide better resolution of the bottom of the magnetic bodies. The 3D models indicate the depth to the bottom of the magnetic bodies varied between 5 and 23 km. Even though both methods produced similar results, the 3D inversion method produced higher resolution of the CPD depths. The shallowest depths (5-8 km) occur along and west of the Brawley Seismic Zone and the southwestern portion of the Imperial Valley. The source of these shallow CPD values may be related to geothermal systems including hydrothermal circulation and/or partially molten material. Additionally, shallow CPD depths (7-12 km) were found in a northwest-trending zone in the center of the Salton Trough. These depths coincide with previous seismic analyses that indicated a lower crustal low velocity region which is believed to be caused by partially molten material. Lower velocity zones in several regions may be related to fracturing and/or hydrothermal fluids. If the majority of these shallow depths are related to temperature, they are likely associated with the CPD, and the partially molten material extends over a wider zone than previously known. Greater depths within the Salton Trough coincide with the base of basaltic material and/or regions of intense metamorphism intruded by mafic material in the middle/lower crust.

Type C botulism in pelicans and other fish-eating birds at the Salton Sea

USGS Publications Warehouse

Rocke, T.E.; Nol, P.; Pelizza, C.; Sturm, K.K.

2004-01-01

In 1996, type C avian botulism killed over 10,000 pelicans and nearly 10,000 other fish-eating birds at the Salton Sea in southern California. Although botulism had been previously documented in waterbirds at the Sea, this die-off was unusual in that it involved primarily fish-eating birds. The American White Pelican (Pelecanus erythrorynchos) was the species with the greatest mortality in 1996. Since 1996, mortality has recurred every year but losses have declined (<2,000 birds/year), with relatively more Brown Pelicans (P. occidentalis) than White Pelicans afflicted. In 2000, morbidity and mortality of Brown Pelicans with type C botulism (1311) approached the numbers afflicted in 1996 (2034). In recent years, mortality reached a peak earlier in the summer, July and August, in contrast to 1996 when mortality reached a peak in September. An exotic fish species, tilapia (Oreochromis mossambicus), has been implicated as the source of toxin for birds at Salton Sea, but the source of toxin for fish is unknown.

Long-term changes in the phosphorus loading to and trophic state of the Salton Sea, California

USGS Publications Warehouse

Robertson, Dale M.; Schladow, S.G.; Holdren, G.C.

2008-01-01

The Salton Sea (Sea) is a eutrophic to hypereutrophic lake characterized by high nutrient concentrations, low water clarity, and high biological productivity. Based on dissolved phosphorus (P) and nitrogen (N) concentrations and N:P ratios, P is typically the limiting nutrient in the Sea and, therefore, should be the primary nutrient of concern when considering management efforts. Flows in the major tributaries to the Sea have been measured since 1965, whereas total P (TP) concentrations were only measured intermittently by various agencies since 1968. These data were used to estimate annual P loading from 1965 to 2002. Annual loads have increased steadily from ???940,000 kg around 1968 to ???1,450,000 kg in 2002 (???55% increase), primarily a result of increased TP concentrations and loads in the New River. Although the eutrophic condition of the Salton Sea is of great concern, only limited nutrient data are available for the Sea. It is difficult to determine whether the eutrophic state of the Sea has degraded or possibly even improved slightly in response to the change in P loading because of variability in the data and changes in the sampling and analytical methodologies. ?? 2008 Springer Science+Business Media B.V.

Thermal and petrologic constraints on lower crustal melt accumulation under the Salton Sea Geothermal Field

NASA Astrophysics Data System (ADS)

Karakas, Ozge; Dufek, Josef; Mangan, Margaret T.; Wright, Heather M.; Bachmann, Olivier

2017-06-01

In the Salton Sea region of southern California (USA), concurrent magmatism, extension, subsidence, and sedimentation over the past 0.5 to 1.0 Ma have led to the creation of the Salton Sea Geothermal Field (SSGF)-the second largest and hottest geothermal system in the continental United States-and the small-volume rhyolite eruptions that created the Salton Buttes. In this study, we determine the flux of mantle-derived basaltic magma that would be required to produce the elevated average heat flow and sustain the magmatic roots of rhyolite volcanism observed at the surface of the Salton Sea region. We use a 2D thermal model to show that a lower-crustal, partially molten mush containing < 20- 40% interstitial melt develops over a ∼105-yr timescale for basalt fluxes of 0.008 to 0.010 m3 /m2 /yr (∼0.0008 to ∼0.001 km3/yr injection rate) given extension rates at or below the current value of ∼0.01 m/yr (Brothers et al., 2009). These regions of partial melt are a natural consequence of a thermal regime that scales with average surface heat flow in the Salton Trough, and are consistent with seismic observations. Our results indicate limited melting and assimilation of pre-existing rocks in the lower crust. Instead, we find that basalt fractionation in the lower crust produces derivative melts of andesitic to dacitic composition. Such melts are then expected to ascend and accumulate in the upper crust, where they further evolve to give rise to small-volume rhyolite eruptions (Salton Buttes) and fuel local spikes in surface heat flux as currently seen in the SSGF. Such upper crustal magma evolution, with limited assimilation of hydrothermally altered material, is required to explain the slight decrease in δ18 O values of zircons (and melts) that have been measured in these rhyolites.

Spatial and temporal assessment of environmental contaminants in water, sediments and fish of the Salton Sea and its two primary tributaries, California, USA, from 2002 to 2012.

PubMed

Xu, Elvis Genbo; Bui, Cindy; Lamerdin, Cassandra; Schlenk, Daniel

2016-07-15

The Salton Sea, the largest inland surface water body in California, has been designated as a sensitive ecological area by federal and state governments. Its two main tributaries, the New River and Alamo River are impacted by urban and agriculture land use wastes. The purpose of this study was to temporally and spatially evaluate the ecological risks of contaminants of concern in water, sediments and fish tissues. A total of 229 semivolatile organic compounds and 12 trace metals were examined. Among them Selenium, DDTs, PAHs, PCBs, chlorpyrifos and some current-use pesticides such as pyrethroids exceeded risk thresholds. From 2002 to 2012, measurements of chlorpyrifos in sediments generally declined and were not observed after 2009 at the river outlets. In contrast, pyrethroid concentrations in sediments rose consistently after 2009. In water samples, the outlets of the two rivers showed relatively higher levels of contamination than the main water body of the Salton Sea. However, sediments of the main water body of the Salton Sea showed relatively higher sediment concentrations of contaminants than the two rivers. This was particularly true for selenium which showed reductions in concentrations from 2002 to 2007, but then gradual increases to 2012. Consistent with water evaluations, contaminant concentrations in fish tissues tended to be higher at the New River boundary and at the drainage sites for the Alamo River compared to sites along each river. The persistent contaminants DDTs, PAHs, chlorpyrifos and several pyrethroid insecticides were associated with the toxicity of sediments and water collected from the rivers. Overall, assessment results suggested potential ecological risk in sediments of the Salton Sea as well as in water and fish from the two rivers. Copyright © 2016 Elsevier B.V. All rights reserved.

Born from a flood: The Salton Sea and its story of survival

DOE PAGES

Tompson, Andrew F. B.

2016-02-02

The Salton Sea is a terminal lake located in the deepest point of the topographically closed Salton Trough in southeastern California. It is currently the largest lake in area in the state. It was created by a flooding event along the Colorado River in 1905–1907, similar to the way historical floods over past centuries created ephemeral incarnations of ancient Lake Cahuilla in the same location. Its position at the center of today’s Imperial Valley, a hot and arid locale home to some of the most productive irrigated agricultural lands in the United States, has ensured its ongoing survival through amore » delicate balance between agricultural runoff, its principal form of input, and vast evaporation losses. Nevertheless, its parallel role as a recreational resource and important wildlife habitat, established over its first century of existence, is threatened by increasing salinity decreasing water quality, and reduced water allocations from the Colorado River that feeds the valley’s agriculture. Furthermore, the Salton Sea faces an increasingly uncertain future that will be influenced by reduced water imports from the Colorado River, demands for additional water sources to support farming and energy industries in the valley, and needs to stabilize the lake salinity, maintain recreational resources, and preserve what have become important ecosystems and wildlife habitats.« less

Born from a flood: The Salton Sea and its story of survival

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tompson, Andrew F. B.

The Salton Sea is a terminal lake located in the deepest point of the topographically closed Salton Trough in southeastern California. It is currently the largest lake in area in the state. It was created by a flooding event along the Colorado River in 1905–1907, similar to the way historical floods over past centuries created ephemeral incarnations of ancient Lake Cahuilla in the same location. Its position at the center of today’s Imperial Valley, a hot and arid locale home to some of the most productive irrigated agricultural lands in the United States, has ensured its ongoing survival through amore » delicate balance between agricultural runoff, its principal form of input, and vast evaporation losses. Nevertheless, its parallel role as a recreational resource and important wildlife habitat, established over its first century of existence, is threatened by increasing salinity decreasing water quality, and reduced water allocations from the Colorado River that feeds the valley’s agriculture. Furthermore, the Salton Sea faces an increasingly uncertain future that will be influenced by reduced water imports from the Colorado River, demands for additional water sources to support farming and energy industries in the valley, and needs to stabilize the lake salinity, maintain recreational resources, and preserve what have become important ecosystems and wildlife habitats.« less

Avian disease at the Salton Sea

USGS Publications Warehouse

Friend, M.

2002-01-01

A review of existing records and the scientific literature was conducted for occurrences of avian diseases affecting free-ranging avifauna within the Salton Sea ecosystem. The period for evaluation was 1907 through 1999. Records of the U.S. Department of Agriculture, Bureau of Biological Survey and the scientific literature were the data sources for the period of 1907a??1939. The narrative reports of the U.S. Fish and Wildlife Service's Sonny Bono National Wildlife Refuge Complex and the epizootic database of the U.S. Geological Survey's National Wildlife Health Center were the primary data sources for the remainder of the evaluation. The pattern of avian disease at the Salton Sea has changed greatly over time. Relative to past decades, there was a greater frequency of major outbreaks of avian disease at the Salton Sea during the 1990s than in previous decades, a greater variety of disease agents causing epizootics, and apparent chronic increases in the attrition of birds from disease. Avian mortality was high for about a decade beginning during the mid-1920s, diminished substantially by the 1940s and was at low to moderate levels until the 1990s when it reached the highest levels reported. Avian botulism (Clostridium botulinum type C) was the only major cause of avian disease until 1979 when the first major epizootic of avian cholera (Pasteurella multocidia) was documented. Waterfowl and shorebirds were the primary species affected by avian botulism. A broader spectrum of species have been killed by avian cholera but waterfowl have suffered the greatest losses. Avian cholera reappeared in 1983 and has joined avian botulism as a recurring cause of avian mortality. In 1989, avian salmonellosis (Salmonella typhimurium) was first diagnosed as a major cause of avian disease within the Salton Sea ecosystem and has since reappeared several times, primarily among cattle egrets (Bubulcus ibis). The largest loss from a single epizootic occurred in 1992, when an estimated

Organochlorine pesticide, polychlorinated biphenyl, trace element and metal residues in bird eggs from Salton Sea, California, 2004

USGS Publications Warehouse

Henny, Charles J.; Anderson, T.W.; Crayon, J.J.

2008-01-01

The Salton Sea is a highly eutrophic, hypersaline terminal lake that receives inflows primarily from agricultural drainages in the Imperial and Coachella valleys. Impending reductions in water inflow at Salton Sea may concentrate existing contaminants which have been a concern for many years, and result in higher exposure to birds. Thus, waterbird eggs were collected and analyzed in 2004 and compared with residue concentrations from earlier years; these data provide a base for future comparisons. Eggs from four waterbird species (black-crowned night-heron [Nycticorax nycticorax], great egret [Ardea alba], black-necked stilt [Himantopus mexicanus], and American avocet [Recurvirostra Americana]) were collected. Eggs were analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), metals, and trace elements, with current results compared to those reported for eggs collected from the same species and others during 1985a??1993. The two contaminants of primary concern were p,pa??-DDE (DDE) and selenium. DDE concentrations in night-heron and great egret eggs collected from the northwest corner of Salton Sea (Whitewater River delta) decreased 91 and 95%, respectively, by 2004, with a concomitant increase in eggshell thickness for both species. Decreases in bird egg DDE levels paralleled those in tissues of tilapia (Oreochromis mossambicus ?? O. urolepis), an important prey species for herons and egrets. Despite most nests of night-herons and great egrets failing in 2004 due to predation, predicted reproductive effects based on DDE concentrations in eggs were low or negligible for these species. The 2004 DDE findings were in dramatic contrast to those in the past decade, and included an 81% decrease in black-necked stilt eggs, although concentrations were lower historically than those reported in night-herons and egrets. Selenium concentrations in black-necked stilt eggs from the southeast corner of Salton Sea (Davis Road) were similar in 1993 and 2004, with 4

Subsidence rates at the southern Salton Sea consistent with reservoir depletion

NASA Astrophysics Data System (ADS)

Barbour, Andrew J.; Evans, Eileen L.; Hickman, Stephen H.; Eneva, Mariana

2016-07-01

Space geodetic measurements from the Envisat satellite between 2003 and 2010 show that subsidence rates near the southeastern shoreline of the Salton Sea in Southern California are up to 52mmyr-1 greater than the far-field background rate. By comparing these measurements with model predictions, we find that this subsidence appears to be dominated by poroelastic contraction associated with ongoing geothermal fluid production, rather than the purely fault-related subsidence proposed previously. Using a simple point source model, we suggest that the source of this proposed volumetric strain is at depths between 1.0 km and 2.4 km (95% confidence interval), comparable to generalized boundaries of the Salton Sea geothermal reservoir. We find that fault slip on two previously imaged tectonic structures, which are part of a larger system of faults in the Brawley Seismic Zone, is not an adequate predictor of surface velocity fields because the magnitudes of the best fitting slip rates are often greater than the full plate boundary rate and at least 2 times greater than characteristic sedimentation rates in this region. Large-scale residual velocity anomalies indicate that spatial patterns predicted by fault slip are incompatible with the observations.

Subsidence rates at the southern Salton Sea consistent with reservoir depletion

USGS Publications Warehouse

Barbour, Andrew J.; Evans, Eileen; Hickman, Stephen H.; Eneva, Mariana

2016-01-01

Space geodetic measurements from the Envisat satellite between 2003 and 2010 show that subsidence rates near the southeastern shoreline of the Salton Sea in Southern California are up to 52mmyr−1 greater than the far-field background rate. By comparing these measurements with model predictions, we find that this subsidence appears to be dominated by poroelastic contraction associated with ongoing geothermal fluid production, rather than the purely fault-related subsidence proposed previously. Using a simple point source model, we suggest that the source of this proposed volumetric strain is at depths between 1.0 km and 2.4 km (95% confidence interval), comparable to generalized boundaries of the Salton Sea geothermal reservoir. We find that fault slip on two previously imaged tectonic structures, which are part of a larger system of faults in the Brawley Seismic Zone, is not an adequate predictor of surface velocity fields because the magnitudes of the best fitting slip rates are often greater than the full plate boundary rate and at least 2 times greater than characteristic sedimentation rates in this region. Large-scale residual velocity anomalies indicate that spatial patterns predicted by fault slip are incompatible with the observations.

Diversity of terrestrial avifauna in response to distance from the shoreline of the Salton Sea

USGS Publications Warehouse

Mendelsohn, M.B.; Boarman, W.I.; Fisher, R.N.; Hathaway, S.A.

2007-01-01

Large aquatic bodies influence surrounding terrestrial ecosystems by providing water and nutrients. In arid landscapes, the increased primary productivity that results may greatly enhance vertebrate biodiversity. The Salton Sea, a large saline lake in the Colorado Desert of southern California, provides nutrients in the form of hundreds of thousands of dead fish carcasses, brine flies, and chemical compounds through windborne salt sea spray. We performed point counts for landbirds and shorebirds monthly or every other month between March 2001 and February 2002 across a sampling grid of 35 points along the west edge of Salton Sea. We found that avian diversity (numbers of species and numbers per species) was dependent on proximity to the Sea. Diversity was at a maximum nearest the shore, and was significantly lower away from the Sea's edge, at all surveyed distances up to 1 km from the shore. Cover by the dominant shrubs on the study site also corresponded to proximity to the water's edge. Whereas one may hypothesize that the avian diversity patterns are caused by these differences in vegetation structure, our data did not support this. Future studies should further investigate this potential correlation between vegetation and bird patterns. Until more is understood about the relationship between elevated avian diversity and the physical environment of the land-shore interface, our results suggest that the Sea's surface be stabilized near its present level. Future management schemes at the Salton Sea that include reductions of water sources should be carefully analyzed, so as to not jeopardize the terrestrial avifauna at this unique ecosystem. ?? 2006 Elsevier Ltd. All rights reserved.

Occurrence, distribution, and transport of pesticides, trace elements, and selected inorganic constituents into the Salton Sea Basin, California, 2001-2002

USGS Publications Warehouse

LeBlanc, Lawrence A.; Schroeder, Roy A.; Orlando, James L.; Kuivila, Kathyrn M.

2004-01-01

A study of pesticide distribution and transport within the Salton Sea Basin, California, was conducted from September 2001 to October 2002. Sampling for the study was done along transects for the three major rivers that flow into the Salton Sea Basin: the New and Alamo Rivers at the southern end of the basin and the Whitewater River at the northern end. Three stations were established on each river: an outlet station approximately 1 mile upstream of the river discharge, a near-shore station in the river delta, and off-shore station in the Salton Sea. Water and suspended and bed sediments were collected at each station in October 2001, March-April 2002, and September 2002, coinciding with peak pesticide applications in the fall and spring. Fourteen current-use pesticides were detected in the water column. Concentrations of dissolved pesticides typically decreased from the outlets to the sea in all three rivers, consistent with the off-shore transport of pesticides from the rivers to the sea. Dissolved concentrations ranged from the limits of detection to 151 nanograms per liter (ng/L); however, diazinon, eptam (EPTC), and malathion were detected at much higher concentrations (940?3,830 ng/L) at the New and Alamo River outlet and near-shore stations. Concentrations of carbaryl, dacthal, diazinon, and eptam were higher during the two fall sampling periods, whereas concentrations of atrazine, carbofuran, and trifluralin were higher during the spring. Current-use pesticides also were detected on suspended and bed sediments in concentrations ranging from method detection limits to 106 ng/g (nanograms per gram). Chlorpyrifos, dacthal, eptam, trifluralin, and DDE were the most frequently detected pesticides on sediments from all three rivers. The number and concentrations of pesticides associated with suspended sediments frequently were similar for the river outlet and near-shore sites, consistent with the downstream transport of sediment-associated pesticides out of the

Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the Salton Sea area, California, 1986-87

USGS Publications Warehouse

Setmire, J.G.; Wolfe, J.C.; Stroud, R.K.

1990-01-01

Water, bottom sediment, and biota were sampled during 1986 and 1987 in the Salton Sea area to determine concentrations of trace elements and pesticides as part of the Department of Interior Irrigation Drainage Program. The sampling sites (12 water, 15 bottom sediment, and 5 biota) were located in the Coachella and Imperial Valleys. The focus of sampling was to determine the current or potential threat to the wildlife of the Salton National Wildlife Refuge from irrigation projects sponsored or operated by the Department of the Interior. Results of the investigation indicate that selenium is the major element of concern. Elevated concentrations of selenium in water were restricted to tile-drain effluent. The maximum selenium concentration of 300 microg/L was detected in a tile-drain sample, and the minimum concentration of 1 microg/L was detected in a composite sample of Salton Sea water. The median selenium concentration was 19 microg/L. In contrast to the water, the highest bottom-sediment selenium concentration of 3.3 mg/kg was in a composite sample from the Salton Sea. The selenium detected in samples of waterfowl and fish also are of concern, but, to date, no studies have been done in the Salton Sea area to determine if selenium has caused adverse biological effects. Concentrations of boron and manganese were elevated in tile-drain samples throughout the Imperial Valley. Boron concentrations in migratory waterfowl were at levels that could cause reproduction impairment. Elevated concentrations of chromium, nickel, and zinc were detected in the Whitewater River , but they were not associated with irrigation drainage. Organochlorine pesticide residues were detected in bottom sediment throughout the study area at levels approaching those measured more than 10 years ago. More detailed studies would be needed to determine if these residues are affecting the waterfowl. (USGS)

Preliminary report on geophysical well-logging activity on the Salton Sea Scientific Drilling Project, Imperial Valley, California

USGS Publications Warehouse

Paillet, Frederick L.; Morin, R.H.; Hodges, H.E.

1986-01-01

The Salton Sea Scientific Drilling Project has culminated in a 10,564-ft deep test well, State 2-14 well, in the Imperial Valley of southern California. A comprehensive scientific program of drilling, coring, and downhole measurements, which was conducted for about 5 months, has obtained much scientific information concerning the physical and chemical processes associated with an active hydrothermal system. This report primarily focuses on the geophysical logging activities at the State 2-14 well and provides early dissemination of geophysical data to other investigators working on complementary studies. Geophysical-log data were obtained by a commercial logging company and by the U.S. Geological Survey (USGS). Most of the commercial logs were obtained during three visits to the site; only one commercial log was obtained below a depth of 6,000 ft. The commercial logs obtained were dual induction, natural gamma, compensated neutron formation density, caliper and sonic. The USGS logging effort consisted of four primary periods, with many logs extending below a depth of 6,000 ft. The USGS logs obtained were temperature, caliper, natural gamma, gamma spectral, epithermal neutron, acoustic velocity, full-waveform, and acoustic televiewer. Various problems occurred throughout the drilling phase of the Salton Sea Scientific Drilling Project that made successful logging difficult: (1) borehole constrictions, possibly resulting from mud coagulation, (2) maximum temperatures of about 300 C, and (3) borehole conditions unfavorable for logging because of numerous zones of fluid loss, cement plugs, and damage caused by repeated trips in and out of the hole. These factors hampered and compromised logging quality at several open-hole intervals. The quality of the logs was dependent on the degree of probe sophistication and sensitivity to borehole-wall conditions. Digitized logs presented were processed on site and are presented in increments of 1,000 ft. A summary of the numerous

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, April and July 2007

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2007-01-01

This report presents the results for two sampling periods during a 4-year monitoring survey to provide a characterization of selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species, and total suspended solids were determined in water samples, and total selenium was determined in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species-western mosquitofish (Gambusia affinis), and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Total selenium concentrations in water for both sampling periods ranged from 1.43 to 47.1 micrograms per liter, predominately as selenate, which is typical of waters leached out of selenium-contaminated marine shales under alkaline and oxidizing conditions. Total selenium concentrations ranged from 0.88 to 20.2 micrograms per gram in biota, and from 0.15 to 28.9 micrograms per gram in detritus and sediment.

Seaview/Westshores High School Gymnasium & Classroom Building, Salton City, California.

ERIC Educational Resources Information Center

Design Cost Data, 2001

2001-01-01

Presents design, construction, and cost data for Salton City, California's, Seaview/Westshores High School Gymnasium and Classroom Building, which is being utilized by the school and surrounding community. Includes a list of project manufacturers and suppliers, along with five photographs and two floor plans. (GR)

Characterizing Novel Archaeal Lineages in Salton Sea Sediments

NASA Astrophysics Data System (ADS)

Tarn, J.; Valentine, D. L.

2016-12-01

Biological communities in extreme environments are often dominated by microorganisms of the domain Archaea. Abundant microbial assemblages of this group are found in the hottest, saltiest, and most thermodynamically-limited ecosystems on earth. These taxing surroundings are thought to impose a state of chronic energy stress on resident organisms due to high costs of cellular maintenance relative to resource availability. Even in more temperate settings, Archaea are regularly associated with low-nutrient lifestyles, reflecting their adaptation to extreme, biologically-limiting conditions, which may be an ancestral, domain-wide trait. In this study, we seek to characterize the Archaeal community of the Salton Sea, where members of this domain are novel and highly abundant. Previous work by Swan et al. in 2010 showed that gradients in salinity, sulfate, carbon and nitrogen across sediment horizons of the Salton Sea are linked to changes in Archaeal dominance and community structure. In light of recent taxonomic revisions of the domain, I reclassified the 107 published small subunit rRNA Archaeal sequences from the 2010 study using updated reference databases. The majority of these Euryarchaeal sequences were reassigned to the so-called DPANN superphylum, with Pacearchaeota-related sequences being very abundant in shallow, organic-rich sediments. In deeper, energy-limited strata, several groups of Bathyarchaeota and one divergent DPANN clade were dominant. Ongoing metagenomic work on these sediment communities is being used to assemble genomes of these novel Archaeal groups. These results will help define genomic adaptations of Salton Sea Archaea to varying levels of energy stress as well as inform future cultivation efforts.

Investigations of a large scale eared grebe (Podiceps nigricollis) die-off at the Salton Sea, California in 1992

USGS Publications Warehouse

Meteyer, C.U.; Audet, D.J.; Rocke, T.E.; Radke, W.; Creekmore, L.H.; Duncan, R.

2004-01-01

An estimated 150,000 Eared Grebes (Podiceps nigricollis) died at the Salton Sea between 16 December 1991 and 21 April 1992. This represented the largest documented mortality event of Eared Grebes at the time and approximately 6% of the North American population. During the die-off, grebes exhibited several uncharacteristic behaviors, such as congregating at freshwater tributaries, repeatedly gulping freshwater, preening excessively, moving onto land, and allowing close approach and/or capture. Avian cholera was diagnosed in Eared Grebes collected along the north and west shoreline of the Sea late in the die-off but not from the majority of the Eared Grebes dying along the south shore. Gross and histological examinations and diagnostic testing for viruses, bacteria, and parasites did not identify the cause of mortality in the majority of Eared Grebes examined from the south shore of the Sea. Liver concentrations of arsenic, chromium, DDE, mercury, selenium, and zinc were elevated in some Eared Grebes, but none of those contaminants exceeded known thresholds for independent lethality. Poisoning by heavy metals, organochlorine, organophosphorus, or carbamate pesticides, avian botulism, and salt were ruled out as the cause of mortality. Hypotheses for the die-off are interactive effects of contaminants, immunosuppression, a yet unidentified biotoxin or pathogen present in the Salton Sea, impairment of feather waterproofing leading to hypothermia, or a unique manifestation of avian cholera that evades laboratory detection.

Selenium concentrations in irrigation drain inflows to the Salton Sea, California, October 2006 and January 2007

USGS Publications Warehouse

May, Thomas W.; Walther, Mike W.; Brumbaugh, William G.

2007-01-01

This report presents raw data on selenium concentrations in samples of water, sediment, detritus, and selected food-chain matrices collected from selected agricultural drains in the southern portion of the Salton Sea during October 2006 and January 2007. Total selenium and selenium species were determined in water samples, whereas total selenium was determined in sediment, detritus, algae, plankton, midge larvae (Family Chironomidae), and two fish species (western mosquitofish, Gambusia affinis, and sailfin molly, Poecilia latipinna).

Particulate Matter Sources and Composition near a Shrinking Saline Lake (Salton Sea)

NASA Astrophysics Data System (ADS)

Frie, A. L.; Dingle, J. H.; Garrison, A.; Ying, S.; Bahreini, R.

2017-12-01

Dried lake beds (playas) are large dust sources in arid regions, and with increased global water demand many large lakes are shrinking. The Salton Sea is an example of one such lake in the early stages of desiccation, with about 15,000 acres of exposed playa. To quantify the impacts of the shrinking lake on airborne particulate matter(PM) composition, PM samples were collected in August of 2015 and February of 2016 near the Salton Sea, CA. These samples were analyzed for total elemental concentration of 15 elements. For these elements, enrichment factors relative to aluminum were calculated and PMF modeling was applied to deconvolve source factors. From these data, desert-like and playa-like sources were estimated to accounted for 45% and 9% of PM10 mass during these sampling periods. PMF results also revealed that playa sources account for 70% of PM10 Na, evidencing playa-driven PM compositional changes. Additionally, PM Se displayed strong seasonal variation, which is thought to be driven by Se volatilization within Salton Sea sediments, playas, or waters.

Transport and distribution of trace elements and other selected inorganic constituents by suspended particulates in the Salton Sea Basin, California, 2001

USGS Publications Warehouse

LeBlanc, L.A.; Schroeder, R.A.

2008-01-01

In order to examine the transport of contaminants associated with river-derived suspended particles in the Salton Sea, California, large volume water samples were collected in transects established along the three major rivers emptying into the Salton Sea in fall 2001. Rivers in this area carry significant aqueous and particulate contaminant loads derived from irrigation water associated with the extensive agricultural activity, as well as wastewater from small and large municipalities. A variety of inorganic constituents, including trace metals, nutrients, and organic carbon were analyzed on suspended material isolated from water samples collected at upriver, near-shore, and off-shore sites established on the Alamo, New, and Whitewater rivers. Concentration patterns showed expected trends, with river-borne metals becoming diluted by organic-rich algal particles of lacustrine origin in off-shore stations. More soluble metals, such as cadmium, copper, and zinc showed a more even distribution between sites in the rivers and off-shore in the lake basin. General distributional trends of trace elements between particulate and aqueous forms were discerned by combining metal concentration data for particulates from this study with historical aqueous metals data. Highly insoluble trace metals, such as iron and aluminum, occurred almost entirely in the particulate phase, while major cations and approximately 95% of selenium were transported in the soluble phase. Evidence for greater reducing conditions in the New compared to the Alamo River was provided by the greater proportion of reduced (soluble) manganese in the New River. Evidence of bioconcentration of selenium and arsenic within the lake by algae was provided by calculating "enrichment" concentration ratios from metal concentrations on the algal-derived particulate samples and the off-shore sites. ?? 2008 Springer Science+Business Media B.V.

The Salton Seismic Imaging Project (SSIP): Rift Processes and Earthquake Hazards in the Salton Trough (Invited)

NASA Astrophysics Data System (ADS)

Hole, J. A.; Stock, J. M.; Fuis, G. S.; Rymer, M. J.; Murphy, J. M.; Sickler, R. R.; Criley, C. J.; Goldman, M.; Catchings, R. D.; Ricketts, J. W.; Gonzalez-Fernandez, A.; Driscoll, N.; Kent, G.; Harding, A. J.; Klemperer, S. L.

2009-12-01

The Salton Seismic Imaging Project (SSIP) and coordinated projects will acquire seismic data in and across the Salton Trough in southern California and northern Mexico, including the Coachella, Imperial, and Mexicali Valleys. These projects address both rifting processes at the northern end of the Gulf of California extensional province and earthquake hazards at the southern end of the San Andreas Fault system. In the central Salton Trough, North American lithosphere appears to have been rifted completely apart. Based primarily on a 1979 seismic refraction project, the 20-22 km thick crust is apparently composed entirely of new crust added by magmatism from below and sedimentation from above. The new data will constrain the style of continental breakup, the role and mode of magmatism, the effects of rapid Colorado River sedimentation upon extension and magmatism, and the partitioning of oblique extension. The southernmost San Andreas Fault is considered at high risk of producing a large damaging earthquake, yet structures of the fault and adjacent basins are poorly constrained. To improve hazard models, SSIP will image the geometry of the San Andreas and Imperial Faults, structure of sedimentary basins in the Salton Trough, and three-dimensional seismic velocity of the crust and uppermost mantle. SSIP and collaborating projects have been funded by several different programs at NSF and the USGS. These projects include seven lines of land refraction and low-fold reflection data, airguns and OBS data in the Salton Sea, coordinated fieldwork for onshore-offshore and 3-D data, and a densely sampled line of broadband stations across the trough. Fieldwork is tentatively scheduled for 2010. Preliminary work in 2009 included calibration shots in the Imperial Valley that quantified strong ground motion and proved lack of harm to agricultural irrigation tile drains from explosive shots. Piggyback and complementary studies are encouraged.

Seismicity and source spectra analysis in Salton Sea Geothermal Field

NASA Astrophysics Data System (ADS)

Cheng, Y.; Chen, X.

2016-12-01

The surge of "man-made" earthquakes in recent years has led to considerable concerns about the associated hazards. Improved monitoring of small earthquakes would significantly help understand such phenomena and the underlying physical mechanisms. In the Salton Sea Geothermal field in southern California, open access of a local borehole network provides a unique opportunity to better understand the seismicity characteristics, the related earthquake hazards, and the relationship with the geothermal system, tectonic faulting and other physical conditions. We obtain high-resolution earthquake locations in the Salton Sea Geothermal Field, analyze characteristics of spatiotemporal isolated earthquake clusters, magnitude-frequency distributions and spatial variation of stress drops. The analysis reveals spatial coherent distributions of different types of clustering, b-value distributions, and stress drop distribution. The mixture type clusters (short-duration rapid bursts with high aftershock productivity) are predominately located within active geothermal field that correlate with high b-value, low stress drop microearthquake clouds, while regular aftershock sequences and swarms are distributed throughout the study area. The differences between earthquakes inside and outside of geothermal operation field suggest a possible way to distinguish directly induced seismicity due to energy operation versus typical seismic slip driven sequences. The spatial coherent b-value distribution enables in-situ estimation of probabilities for M≥3 earthquakes, and shows that the high large-magnitude-event (LME) probability zones with high stress drop are likely associated with tectonic faulting. The high stress drop in shallow (1-3 km) depth indicates the existence of active faults, while low stress drops near injection wells likely corresponds to the seismic response to fluid injection. I interpret the spatial variation of seismicity and source characteristics as the result of fluid

Diversity patterns in the terrestrial avifauna of the Salton sea

Treesearch

Mark B. Mendelsohn; William I. Boarman; Robert N. Fisher

2005-01-01

We performed bird point counts monthly March-June 2001 and bi-monthly August 2001-February 2002 across a sampling grid of 35 points along the west edge of Salton Sea. We found that landbird species diversity (both in numbers of species, and numbers per species) was dependent on proximity to the sea. Diversity was at a maximum nearest the shore, and was significantly...

Monitoring reservoir response to earthquakes and fluid extraction, Salton Sea geothermal field, California

PubMed Central

Taira, Taka’aki; Nayak, Avinash; Brenguier, Florent; Manga, Michael

2018-01-01

Continuous monitoring of in situ reservoir responses to stress transients provides insights into the evolution of geothermal reservoirs. By exploiting the stress dependence of seismic velocity changes, we investigate the temporal evolution of the reservoir stress state of the Salton Sea geothermal field (SSGF), California. We find that the SSGF experienced a number of sudden velocity reductions (~0.035 to 0.25%) that are most likely caused by openings of fractures due to dynamic stress transients (as small as 0.08 MPa and up to 0.45 MPa) from local and regional earthquakes. Depths of velocity changes are estimated to be about 0.5 to 1.5 km, similar to the depths of the injection and production wells. We derive an empirical in situ stress sensitivity of seismic velocity changes by relating velocity changes to dynamic stresses. We also observe systematic velocity reductions (0.04 to 0.05%) during earthquake swarms in mid-November 2009 and late-December 2010. On the basis of volumetric static and dynamic stress changes, the expected velocity reductions from the largest earthquakes with magnitude ranging from 3 to 4 in these swarms are less than 0.02%, which suggests that these earthquakes are likely not responsible for the velocity changes observed during the swarms. Instead, we argue that velocity reductions may have been induced by poroelastic opening of fractures due to aseismic deformation. We also observe a long-term velocity increase (~0.04%/year) that is most likely due to poroelastic contraction caused by the geothermal production. Our observations demonstrate that seismic interferometry provides insights into in situ reservoir response to stress changes. PMID:29326977

Monitoring reservoir response to earthquakes and fluid extraction, Salton Sea geothermal field, California.

PubMed

Taira, Taka'aki; Nayak, Avinash; Brenguier, Florent; Manga, Michael

2018-01-01

Continuous monitoring of in situ reservoir responses to stress transients provides insights into the evolution of geothermal reservoirs. By exploiting the stress dependence of seismic velocity changes, we investigate the temporal evolution of the reservoir stress state of the Salton Sea geothermal field (SSGF), California. We find that the SSGF experienced a number of sudden velocity reductions (~0.035 to 0.25%) that are most likely caused by openings of fractures due to dynamic stress transients (as small as 0.08 MPa and up to 0.45 MPa) from local and regional earthquakes. Depths of velocity changes are estimated to be about 0.5 to 1.5 km, similar to the depths of the injection and production wells. We derive an empirical in situ stress sensitivity of seismic velocity changes by relating velocity changes to dynamic stresses. We also observe systematic velocity reductions (0.04 to 0.05%) during earthquake swarms in mid-November 2009 and late-December 2010. On the basis of volumetric static and dynamic stress changes, the expected velocity reductions from the largest earthquakes with magnitude ranging from 3 to 4 in these swarms are less than 0.02%, which suggests that these earthquakes are likely not responsible for the velocity changes observed during the swarms. Instead, we argue that velocity reductions may have been induced by poroelastic opening of fractures due to aseismic deformation. We also observe a long-term velocity increase (~0.04%/year) that is most likely due to poroelastic contraction caused by the geothermal production. Our observations demonstrate that seismic interferometry provides insights into in situ reservoir response to stress changes.

The Salton Seismic Imaging Project: Tomographic characterization of a sediment-filled rift valley and adjacent ranges, southern California

NASA Astrophysics Data System (ADS)

Davenport, K.; Hole, J. A.; Stock, J. M.; Fuis, G. S.; Carrick, E.; Tikoff, B.

2011-12-01

The Salton Trough in Southern California represents the northernmost rift of the Gulf of California extensional system. Relative motion between the Pacific and North American plates is accommodated by continental rifting in step-over zones between the San Andreas, Imperial, and Cerro Prieto transform faults. Rapid sedimentation from the Colorado River has isolated the trough from the southern portion of the Gulf of California, progressively filling the subsiding rift basin. Based on data from previous seismic surveys, the pre-existing continent has ruptured completely, and a new ~22 km thick crust has been created entirely by sedimentation overlying rift-related magmatism. The MARGINS, EarthScope, and USGS-funded Salton Seismic Imaging Project (SSIP) was designed to investigate the nature of this new crust, the ongoing process of continental rifting, and associated earthquake hazards. SSIP, acquired in March 2011, comprises 7 lines of onshore seismic refraction / wide-angle reflection data, 2 lines of refraction / reflection data in the Salton Sea, and a line of broadband stations. This presentation focuses on the refraction / wide-angle reflection line across the Imperial Valley, extending ~220 km across California from Otay Mesa, near Tijuana, to the Colorado River. The data from this line includes seventeen 100-160 kg explosive shots and receivers at 100 m spacing across the Imperial Valley to constrain the structure of the Salton Trough rift basin, including the Imperial Fault. Eight larger shots (600-920 kg) at 20-35 km spacing and receivers at 200-500 m spacing extend the line across the Peninsular Ranges and the Chocolate Mountains. These data will contrast the structure of the rift to that of the surrounding crust and provide constraints on whole-crust and uppermost mantle structure. Preliminary work has included tomographic inversion of first-arrival travel times across the Valley, emphasizing a minimum-structure approach to create a velocity model of the

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, April and July 2008

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2009-01-01

This report presents the results for two sampling periods (April 2008 and July 2008) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (dissolved selenite, selenate, organoselenium), and total suspended solids were determined in water samples and total selenium was determined in water column particulates and in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species - western mosquitofish (Gambusia affinis) and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 1.93 to 44.2 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 0.75 to 3.39; plankton, 0.88 to 4.03; midges, 2.52 to 44.3; fish, 3.37 to 18.9; detritus, 1.11 to 13.6; sediment, 0.11 to 8.93.

Comprehensive analysis of earthquake source spectra and swarms in the Salton Trough, California

NASA Astrophysics Data System (ADS)

Chen, X.; Shearer, P. M.

2011-09-01

We study earthquakes within California's Salton Trough from 1981 to 2009 from a precisely relocated catalog. We process the seismic waveforms to isolate source spectra, station spectra and travel-time dependent spectra. The results suggest an average P wave Q of 340, agreeing with previous results indicating relatively high attenuation in the Salton Trough. Stress drops estimated from the source spectra using an empirical Green's function (EGF) method reveal large scatter among individual events but a low median stress drop of 0.56 MPa for the region. The distribution of stress drop after applying a spatial-median filter indicates lower stress drops near geothermal sites. We explore the relationships between seismicity, stress drops and geothermal injection activities. Seismicity within the Salton Trough shows strong spatial clustering, with 20 distinct earthquake swarms with at least 50 events. They can be separated into early-Mmax and late-Mmax groups based on the normalized occurrence time of their largest event. These swarms generally have a low skew value of moment release history, ranging from -9 to 3.0. The major temporal difference between the two groups is the excess of seismicity and an inverse power law increase of seismicity before the largest event for the late-Mmax group. All swarms exhibit spatial migration of seismicity at a statistical significance greater than 85%. A weighted L1-norm inversion of linear migration parameters yields migration velocities from 0.008 to 0.8 km/hour. To explore the influence of fluid injection in geothermal sites, we also model the migration behavior with the diffusion equation, and obtain a hydraulic diffusion coefficient of approximately 0.25 m2/s for the Salton Sea geothermal site, which is within the range of expected values for a typical geothermal reservoir. The swarms with migration velocities over 0.1 km/hour cannot be explained by the diffusion curve, rather, their velocity is consistent with the propagation

Continental rupture and the creation of new crust in the Salton Trough rift, Southern California and northern Mexico: Results from the Salton Seismic Imaging Project

NASA Astrophysics Data System (ADS)

Han, Liang; Hole, John A.; Stock, Joann M.; Fuis, Gary S.; Kell, Annie; Driscoll, Neal W.; Kent, Graham M.; Harding, Alistair J.; Rymer, Michael J.; González-Fernández, Antonio; Lázaro-Mancilla, Octavio

2016-10-01

A refraction and wide-angle reflection seismic profile along the axis of the Salton Trough, California and Mexico, was analyzed to constrain crustal and upper mantle seismic velocity structure during active continental rifting. From the northern Salton Sea to the southern Imperial Valley, the crust is 17-18 km thick and approximately one-dimensional. The transition at depth from Colorado River sediment to underlying crystalline rock is gradual and is not a depositional surface. The crystalline rock from 3 to 8 km depth is interpreted as sediment metamorphosed by high heat flow. Deeper felsic crystalline rock could be stretched preexisting crust or higher-grade metamorphosed sediment. The lower crust below 12 km depth is interpreted to be gabbro emplaced by rift-related magmatic intrusion by underplating. Low upper mantle velocity indicates high temperature and partial melting. Under the Coachella Valley, sediment thins to the north and the underlying crystalline rock is interpreted as granitic basement. Mafic rock does not exist at 12-18 km depth as it does to the south, and a weak reflection suggests Moho at 28 km depth. Structure in adjacent Mexico has slower midcrustal velocity, and rocks with mantle velocity must be much deeper than in the Imperial Valley. Slower velocity and thicker crust in the Coachella and Mexicali valleys define the rift zone between them to be >100 km wide in the direction of plate motion. North American lithosphere in the central Salton Trough has been rifted apart and is being replaced by new crust created by magmatism, sedimentation, and metamorphism.

Continental rupture and the creation of new crust in the Salton Trough rift, southern California and northern Mexico: Results from the Salton Seismic Imaging Project

USGS Publications Warehouse

Han, Liang; Hole, John A.; Stock, Joann M.; Fuis, Gary S.; Kell, Annie; Driscoll, Neal W.; Kent, Graham M.; Rymer, Michael J.; Gonzalez-Fernandez, Antonio; Aburto-Oropeza, Octavio

2016-01-01

A refraction and wide-angle reflection seismic profile along the axis of the Salton Trough, California and Mexico, was analyzed to constrain crustal and upper mantle seismic velocity structure during active continental rifting. From the northern Salton Sea to the southern Imperial Valley, the crust is 17-18 km thick and approximately one-dimensional. The transition at depth from Colorado River sediment to underlying crystalline rock is gradual and is not a depositional surface. The crystalline rock from ~3 to ~8 km depth is interpreted as sediment metamorphosed by high heat flow. Deeper felsic crystalline rock could be stretched pre-existing crust or higher grade metamorphosed sediment. The lower crust below ~12 km depth is interpreted to be gabbro emplaced by rift-related magmatic intrusion by underplating. Low upper-mantle velocity indicates high temperature and partial melting. Under the Coachella Valley, sediment thins to the north and the underlying crystalline rock is interpreted as granitic basement. Mafic rock does not exist at 12-18 depth as it does to the south, and a weak reflection suggests Moho at ~28 km depth. Structure in adjacent Mexico has slower mid-crustal velocity and rocks with mantle velocity must be much deeper than in the Imperial Valley. Slower velocity and thicker crust in the Coachella and Mexicali valleys define the rift zone between them to be >100 km wide in the direction of plate motion. North American lithosphere in the central Salton Trough has been rifted apart and is being replaced by new crust created by magmatism, sedimentation, and metamorphism.

Simulation of Wind-Driven Circulation in the Salton Sea: Implications for Indigenous Ecosystems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, Chris B.; Orlob, Gerald T.; Huston, David W.

The Salton Sea Authority is seeking methods for reducing water levels and controlling salinity within ranges that will protect beneficial uses of the Sea, its adjacent lands, and its indigenous ecosystems. Proposed solutions include various physical changes in the bathymetry and configuration of the Sea. Because circulation in the Sea is driven primarily by wind stresses imposed on the water surface, and circulation changes are likely to affect the Sea?s quality and ecology, a methodology for quantifying the effects of specific alternatives is required. For this purpose a mathematical model for simulation of the hydrodynamic behavior of the Sea hasmore » been developed, calibrated to data gathered by a field investigation conducted in 1997, and applied to alternative schemes that will isolate sections of the southern basin. The Salton Sea Hydrodynamic/Water Quality Model is constructed using the finite element method to represent the bathymetry of the Sea in a three-dimensional grid. Given certain boundary conditions, for example wind stresses imposed on the surface, the model solves the three-dimensional equations of motion and continuity, the advection-dispersion equation, and an equation of state dependent upon temperature and salinity, to obtain temporal and spatial descriptions of velocities and temperatures over a specified period of time. The model successfully replicated principal features of the Sea's behavior, especially the persistence of a counterclockwise gyre in the southern basin and seasonal stratification. Once calibrated, the model was applied to evaluate the possible effects of changing water surface elevations in the Sea and altering its configuration to isolate sections for evaporative concentration of salts. These effects, evident in changes in velocity, were quantified with regard to their possible impacts on the aquatic habitat and the health of the Salton Sea ecology. A comparative evaluation of alternatives is presented.« less

The Effect of a Receding Saline Lake (The Salton Sea) on Airborne Particulate Matter Composition.

PubMed

Frie, Alexander L; Dingle, Justin H; Ying, Samantha C; Bahreini, Roya

2017-08-01

The composition of ambient particulate matter (PM) and its sources were investigated at the Salton Sea, a shrinking saline lake in California. To investigate the influence of playa exposure on PM composition, PM samples were collected during two seasons and at two sites around the Salton Sea. To characterize source composition, soil samples were collected from local playa and desert surfaces. PM and soil samples were analyzed for 15 elements using mass spectrometry and X-ray diffraction. The contribution of sources to PM mass and composition was investigated using Al-referenced enrichment factors (EFs) and source factors resolved from positive matrix factorization (PMF). Playa soils were found to be significantly enriched in Ca, Na, and Se relative to desert soils. PMF analysis resolved the PM 10 data with four source factors, identified as Playa-like, Desert-like, Ca-rich, and Se. Playa-like and desert-like sources were estimated to contribute to a daily average of 8.9% and 45% of PM 10 mass, respectively. Additionally, playa sources were estimated to contribute to 38-68% of PM 10 Na. PM 10 Se concentrations showed strong seasonal variations, suggesting a seasonal cycle of Se volatilization and recondensation. These results support the importance of playas as a source of PM mass and a controlling factor of PM composition.

A comparison of long-term changes in seismicity at The Geysers, Salton Sea, and Coso geothermal fields

NASA Astrophysics Data System (ADS)

Trugman, Daniel T.; Shearer, Peter M.; Borsa, Adrian A.; Fialko, Yuri

2016-01-01

Geothermal energy is an important source of renewable energy, yet its production is known to induce seismicity. Here we analyze seismicity at the three largest geothermal fields in California: The Geysers, Salton Sea, and Coso. We focus on resolving the temporal evolution of seismicity rates, which provides important observational constraints on how geothermal fields respond to natural and anthropogenic loading. We develop an iterative, regularized inversion procedure to partition the observed seismicity rate into two components: (1) the interaction rate due to earthquake-earthquake triggering and (2) the smoothly varying background rate controlled by other time-dependent stresses, including anthropogenic forcing. We apply our methodology to compare long-term changes in seismicity to monthly records of fluid injection and withdrawal. At The Geysers, we find that the background seismicity rate is highly correlated with fluid injection, with the mean rate increasing by approximately 50% and exhibiting strong seasonal fluctuations following construction of the Santa Rosa pipeline in 2003. In contrast, at both Salton Sea and Coso, the background seismicity rate has remained relatively stable since 1990, though both experience short-term rate fluctuations that are not obviously modulated by geothermal plant operation. We also observe significant temporal variations in Gutenberg-Richter b value, earthquake magnitude distribution, and earthquake depth distribution, providing further evidence for the dynamic evolution of stresses within these fields. The differing field-wide responses to fluid injection and withdrawal may reflect differences in in situ reservoir conditions and local tectonics, suggesting that a complex interplay of natural and anthropogenic stressing controls seismicity within California's geothermal fields.

Shallow Crustal Structure in the Northern Salton Trough, California: Insights from a Detailed 3-D Velocity Model

NASA Astrophysics Data System (ADS)

Ajala, R.; Persaud, P.; Stock, J. M.; Fuis, G. S.; Hole, J. A.; Goldman, M.; Scheirer, D. S.

2017-12-01

The Coachella Valley is the northern extent of the Gulf of California-Salton Trough. It contains the southernmost segment of the San Andreas Fault (SAF) for which a magnitude 7.8 earthquake rupture was modeled to help produce earthquake planning scenarios. However, discrepancies in ground motion and travel-time estimates from the current Southern California Earthquake Center (SCEC) velocity model of the Salton Trough highlight inaccuracies in its shallow velocity structure. An improved 3-D velocity model that better defines the shallow basin structure and enables the more accurate location of earthquakes and identification of faults is therefore essential for seismic hazard studies in this area. We used recordings of 126 explosive shots from the 2011 Salton Seismic Imaging Project (SSIP) to SSIP receivers and Southern California Seismic Network (SCSN) stations. A set of 48,105 P-wave travel time picks constituted the highest-quality input to a 3-D tomographic velocity inversion. To improve the ray coverage, we added network-determined first arrivals at SCSN stations from 39,998 recently relocated local earthquakes, selected to a maximum focal depth of 10 km, to develop a detailed 3-D P-wave velocity model for the Coachella Valley with 1-km grid spacing. Our velocity model shows good resolution ( 50 rays/cubic km) down to a minimum depth of 7 km. Depth slices from the velocity model reveal several interesting features. At shallow depths ( 3 km), we observe an elongated trough of low velocity, attributed to sediments, located subparallel to and a few km SW of the SAF, and a general velocity structure that mimics the surface geology of the area. The persistence of the low-velocity sediments to 5-km depth just north of the Salton Sea suggests that the underlying basement surface, shallower to the NW, dips SE, consistent with interpretation from gravity studies (Langenheim et al., 2005). On the western side of the Coachella Valley, we detect depth-restricted regions of

Sources of subsidence at the Salton Sea Geothermal Field

USGS Publications Warehouse

Barbour, Andrew J.; Evans, Eileen; Hickman, Stephen H.; Eneva, Mariana

2016-01-01

At the Salton Sea Geothermal Field (SSGF) in Southern California, surface deformation associated with geologic processes including sediment compaction, tectonic strain, and fault slip may be augmented by energy production activities. Separating the relative contributions from natural and anthropogenic sources is especially important at the SSGF, which sits at the apex of a complex tectonic transition zone connecting the southern San Andreas Fault with the Imperial Fault; but this has been a challenging task so far. Here we analyze vertical surface velocities obtained from the persistent scatterer InSAR method and find that two of the largest subsidence anomalies can be represented by a set of volumetric strain nuclei at depths comparable to geothermal well completion zones. In contrast, the rates needed to achieve an adequate fit to the magnitudes of subsidence are almost an order of magnitude greater than rates reported for annual changes in aggregate net-production volume, suggesting that the physical mechanism responsible for subsidence at the SSGF is a complicated interplay between natural and anthropogenic sources.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, October 2007 and January 2008

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2008-01-01

This report presents the results for two sampling periods (October 2007 and January 2008) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (selenite, selenate, organoselenium), and total suspended solids were determined in water samples, and total selenium was determined in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species?western mosquitofish (Gambusia affinis) and sailfin molly (Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 0.97 to 64.5 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 0.95 to 5.99; plankton, 0.15 to 19.3; midges, 1.39 to 15.4; fish, 3.71 to 25.1; detritus, 0.85 to 21.7; sediment, 0.32 to 7.28.

Total selenium and selenium species in irrigation drain inflows to the Salton Sea, California, October 2008 and January 2009

USGS Publications Warehouse

May, Thomas W.; Walther, Michael J.; Saiki, Michael K.; Brumbaugh, William G.

2009-01-01

This report presents the results for two sampling periods (October 2008 and January 2009) during a 4-year monitoring program to characterize selenium concentrations in selected irrigation drains flowing into the Salton Sea, California. Total selenium, selenium species (dissolved selenite, selenate, organoselenium), and total suspended solids were determined in water samples. Total selenium also was determined in water column particulates and in sediment, detritus, and biota that included algae, plankton, midge larvae (family, Chironomidae), and two fish species (western mosquitofish, Gambusia affinis, and sailfin molly, Poecilia latipinna). In addition, sediments were analyzed for percent total organic carbon and particle size. Mean total selenium concentrations in water for both sampling periods ranged from 1.00 to 33.6 micrograms per liter, predominately as selenate, which is typical of waters where selenium is leached out of selenium-containing marine shales and associated soils under alkaline and oxidizing conditions. Total selenium concentrations (micrograms per gram dry weight) ranged as follows: algae, 1.52 to 8.26; plankton, 0.79 to 3.66; midges, 2.68 to 50.6; fish, 3.09 to 30.4; detritus, 1.78 to 58.0; and sediment, 0.42 to 10.0.

Site-Specific Research Conducted in Support of the Salton Sea Solar Pond Project - FY 1982 Report

NASA Technical Reports Server (NTRS)

French, R. L.; Marsh, H. E.; Roschke, E. J.; Wu, Y. C.

1984-01-01

The design and operation of a salt-gradient solar pond power plant at the Salton Sea presents problems not encountered at small research ponds that were built in the United States. The specific characteristics of the Salton Sea site and the desire to construct the pond using the local clay as a sealant represent major deviations from previous solar pond experience. The site-specific research in support of the plant design is described. The research activity included validation of the spectrophotometric light transmission measurement technique, a search for options for clarifying the turbid and colored water of the Salton Sea, development of water clarification specifications in terms common to industry practice, quantification of gas production from microbiological reactions in the ground, a determination of the combined effects of temperature and salinity on the permeation of the local clays, and a preliminary evaluation of material corrosion.

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

NASA Astrophysics Data System (ADS)

Stock, J. M.

2013-12-01

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

The Potential for Renewable Energy Development to Benefit Restoration of the Salton Sea. Analysis of Technical and Market Potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gagne, Douglas; Haase, Scott; Oakleaf, Brett

This report summarizes the potential for renewable energy development in the Salton Sea region, as well as the potential for revenues from this development to contribute financially to Salton Sea restoration costs. It considers solar, geothermal, biofuels or nutraceutical production from algae pond cultivation, desalination using renewable energy, and mineral recovery from geothermal fluids.

A linked hydrodynamic and water quality model for the Salton Sea

USGS Publications Warehouse

Chung, E.G.; Schladow, S.G.; Perez-Losada, J.; Robertson, Dale M.

2008-01-01

A linked hydrodynamic and water quality model was developed and applied to the Salton Sea. The hydrodynamic component is based on the one-dimensional numerical model, DLM. The water quality model is based on a new conceptual model for nutrient cycling in the Sea, and simulates temperature, total suspended sediment concentration, nutrient concentrations, including PO4-3, NO3-1 and NH4+1, DO concentration and chlorophyll a concentration as functions of depth and time. Existing water temperature data from 1997 were used to verify that the model could accurately represent the onset and breakup of thermal stratification. 1999 is the only year with a near-complete dataset for water quality variables for the Salton Sea. The linked hydrodynamic and water quality model was run for 1999, and by adjustment of rate coefficients and other water quality parameters, a good match with the data was obtained. In this article, the model is fully described and the model results for reductions in external phosphorus load on chlorophyll a distribution are presented. ?? 2008 Springer Science+Business Media B.V.

Atmospheric dry deposition in the vicinity of the Salton Sea, California - II: Measurement and effects of an enhanced evaporation system

USGS Publications Warehouse

Alonso, R.; Bytnerowicz, A.; Yee, J.L.; Boarman, W.I.

2005-01-01

A study was conducted to determine the effects of salt spray drift from pilot technologies employed by the US Bureau of Reclamation on deposition rates of various air-born ions. An enhanced evaporation system (EES) was tested in the field at the Salton Sea, California. Dry deposition of NO3-, NH4+, SO42-, Cl-, Ca2+, Na+, K+ and Se was assessed by using nylon filters and branches of natural vegetation exposed for one-week long periods. The simultaneous exposure of both lyophilized branches and branches of live plants offered important information highlighting the dynamics of deposited ions on vegetation. The EES significantly increased the deposition rates of Cl-, SO42- and Na+ in an area of about 639-1062 m surrounding the sprayers. Similarly, higher deposition of Ca 2+ and K+ caused by the EES was detected only when deposition was assessed using nylon filters or lyophilized branches. Deposition fluxes of NO3-, NH4+ and Se were not affected by the spraying system. Techniques for measuring dry deposition and calculating landscape-level depositional loads in non-forested systems need further development. ?? 2005 Elsevier Ltd. All rights reserved.

Salton Trough regional deformation estimated from combined trilateration and survey-mode GPS data

USGS Publications Warehouse

Anderson, G.; Agnew, D.C.; Johnson, H.O.

2003-01-01

The Salton Trough in southeastern California, United States, has one of the highest seismicity and deformation rates in southern California, including 20 earthquakes M 6 or larger since 1892. From 1972 through 1987, the U.S. Geological Survey (USGS) measured a 41-station trilateration network in this region. We remeasured 37 of the USGS baselines using survey-mode Global Positioning System methods from 1995 through 1999. We estimate the Salton Trough deformation field over a nearly 30-year period through combined analysis of baseline length time series from these two datasets. Our primary result is that strain accumulation has been steady over our observation span, at a resolution of about 0.05 ??strain/yr at 95% confidence, with no evidence for significant long-term strain transients despite the occurrence of seven large regional earthquakes during our observation period. Similar to earlier studies, we find that the regional strain field is consistent with 0.5 ?? 0.03 ??strain/yr total engineering shear strain along an axis oriented 311.6?? ?? 23?? east of north, approximately parallel to the strike of the major regional faults, the San Andreas and San Jacinto (all uncertainties in the text and tables are standard deviations unless otherwise noted). We also find that (1) the shear strain rate near the San Jacinto fault is at least as high as it is near the San Andreas fault, (2) the areal dilatation near the southeastern Salton Sea is significant, and (3) one station near the southeastern Salton Sea moved anomalously during the period 1987.95-1995.11.

Loading of the San Andreas fault by flood-induced rupture of faults beneath the Salton Sea

USGS Publications Warehouse

Brothers, Daniel; Kilb, Debi; Luttrell, Karen; Driscoll, Neal W.; Kent, Graham

2011-01-01

The southern San Andreas fault has not experienced a large earthquake for approximately 300 years, yet the previous five earthquakes occurred at ~180-year intervals. Large strike-slip faults are often segmented by lateral stepover zones. Movement on smaller faults within a stepover zone could perturb the main fault segments and potentially trigger a large earthquake. The southern San Andreas fault terminates in an extensional stepover zone beneath the Salton Sea—a lake that has experienced periodic flooding and desiccation since the late Holocene. Here we reconstruct the magnitude and timing of fault activity beneath the Salton Sea over several earthquake cycles. We observe coincident timing between flooding events, stepover fault displacement and ruptures on the San Andreas fault. Using Coulomb stress models, we show that the combined effect of lake loading, stepover fault movement and increased pore pressure could increase stress on the southern San Andreas fault to levels sufficient to induce failure. We conclude that rupture of the stepover faults, caused by periodic flooding of the palaeo-Salton Sea and by tectonic forcing, had the potential to trigger earthquake rupture on the southern San Andreas fault. Extensional stepover zones are highly susceptible to rapid stress loading and thus the Salton Sea may be a nucleation point for large ruptures on the southern San Andreas fault.

Platyamoeba pseudovannellida n. sp., a naked amoeba with wide salt tolerance isolated from the Salton Sea, California.

PubMed

Hauer, G; Rogerson, A; Anderson, O R

2001-01-01

A new species of naked amoeba, Platyamoeba pseudovannellida n.sp., is described on the basis of light microscopic and fine structural features. The amoeba was isolated from the Salton Sea, California, from water at a salinity of ca. 44%. Locomotive amoebae occasionally had a spatulate outline and floating cells had radiating pseudopodia, sometimes with pointed tips. Both these features are reminiscent of the genus Vannella. However, the surface coat (glycocalyx) as revealed by TEM indicates that this is a species of Platyamoeba. Although salinity was not used as a diagnostic feature, this species was found to have remarkable tolerance to fluctuating salinity levels, even when changes were rapid. Amoebae survived over the range 0 per thousand to 150 per thousand salt and grew within the range 0 per thousand to 138 per thousand salt. The generation time of cells averaged 29 h and was not markedly affected by salt concentration. This is longer than expected for an amoeba of this size and suggests a high energetic cost of coping with salinity changes. The morphology of cells changed with increasing salinity: at 0 per thousand cells were flattened and active and at the other extreme (138 per thousand) amoebae were wrinkled and domed and cell movement was very slow. At the ultrastructural level, the cytoplasm of cells grown at high salinity (98 per thousand was considerably denser than that of cells reared at 0 per thousand.

Metamorphosed Plio-Pleistocene evaporites and the origins of hypersaline brines in the Salton Sea geothermal system, California: Fluid inclusion evidence

NASA Astrophysics Data System (ADS)

McKibben, Michael A.; Williams, Alan E.; Okubo, Susumu

1988-05-01

The Salton Sea geothermal system (SSGS) occurs in Plio-Pleistocene deltaic-lacustrine-evaporite sediments deposited in the Salton Trough, an active continental rift zone. Temperatures up to 365°C and hypersaline brines with up to 26 wt.% TDS are encountered at 1-3 km depth in the sediments, which are undergoing active greenschist facies hydrothermal metamorphism. Previous models for the origins of the Na-Ca-K-Cl brines have assumed that the high salinities were derived mainly from the downward percolation of cold, dense brines formed by low-temperature dissolution of shallow non-marine evaporites. New drillcores from the central part of the geothermal field contain metamorphosed, bedded evaporites at 1 km depth consisting largely of hornfelsic anhydrite interbedded with anhydrite-cemented solution-collapse shale breccias. Fluid inclusions trapped within the bedded and breccia-cementing anhydrite homogenize at 300°C (identical to the measured downhole temperature) and contain saline Na-Ca-K-Cl brines. Some of the inclusions contain up to 50 vol.% halite, sylvite and carbonate crystals at room temperature, and some halite crystals persist to above 300°C upon laboratory heating. The data are consistent with the trapping of halite-saturated Na-Ca-K-Cl fluids during hydrothermal metamorphism of the evaporites and accompanying solution collapse of interbedded shales. We conclude that many of the salt crystals in inclusions are the residuum of bedded evaporitic salt that was dissolved during metamorphism by heated connate fluids. Therefore, the high salinities of the Salton Sea geothermal brines are derived in part from the in situ hydrothermal metamorphism and dissolution of halides and CaSO 4 from relatively deeply-buried lacustrine evaporites. This fact places important constraints on modeling fluid-flow in the SSGS, as brines need not have migrated over great distances. The brines have been further modified to their present complex Na-Ca-K-Fe-Mn-Cl compositions by

Host selection patterns of Culex tarsalis (Diptera: Culicidae) at wetlands near the Salton Sea, Coachella Valley, California, 1998-2002.

PubMed

Reisen, William K; Lothrop, Hugh D; Thiemann, Tara

2013-09-01

The bloodmeal hosts used by Culex tarsalis Coquillett collected along the Salton Sea in Coachella Valley, CA, during 1998-2002 were identified using sequences of the cytochrome c oxidase I gene identified from Barcode of Life database. Overall, 265 (83.3%) of 318 bloodmeals were identified, of which 76.6% fed on birds, 18.1% on mammals, and 5.3% on reptiles. Forty-seven different hosts were identified, none of which comprised > 12.5% of the total. Although Cx. tarsalis exhibits specific host-seeking flight patterns, bloodmeals seemed to be acquired opportunistically, thereby limiting potential arbovirus transmission efficiency in species-rich environments.

New insights into North America-Pacific Plate boundary deformation from Lake Tahoe, Salton Sea and southern Baja California

NASA Astrophysics Data System (ADS)

Brothers, Daniel Stephen

Five studies along the Pacific-North America (PA-NA) plate boundary offer new insights into continental margin processes, the development of the PA-NA tectonic margin and regional earthquake hazards. This research is based on the collection and analysis of several new marine geophysical and geological datasets. Two studies used seismic CHIRP surveys and sediment coring in Fallen Leaf Lake (FLL) and Lake Tahoe to constrain tectonic and geomorphic processes in the lakes, but also the slip-rate and earthquake history along the West Tahoe-Dollar Point Fault. CHIRP profiles image vertically offset and folded strata that record deformation associated with the most recent event (MRE). Radiocarbon dating of organic material extracted from piston cores constrain the age of the MRE to be between 4.1--4.5 k.y. B.P. Offset of Tioga aged glacial deposits yield a slip rate of 0.4--0.8 mm/yr. An ancillary study in FLL determined that submerged, in situ pine trees that date to between 900-1250 AD are related to a medieval megadrought in the Lake Tahoe Basin. The timing and severity of this event match medieval megadroughts observed in the western United States and in Europe. CHIRP profiles acquired in the Salton Sea, California provide new insights into the processes that control pull-apart basin development and earthquake hazards along the southernmost San Andreas Fault. Differential subsidence (>10 mm/yr) in the southern sea suggests the existence of northwest-dipping basin-bounding faults near the southern shoreline. In contrast to previous models, the rapid subsidence and fault architecture observed in the southern part of the sea are consistent with experimental models for pull-apart basins. Geophysical surveys imaged more than 15 ˜N15°E oriented faults, some of which have produced up to 10 events in the last 2-3 kyr. Potentially 2 of the last 5 events on the southern San Andreas Fault (SAF) were synchronous with rupture on offshore faults, but it appears that ruptures on

Chemistry and geothermometry of brine produced from the Salton Sea Scientific drill hole, Imperial Valley, California

USGS Publications Warehouse

Thompson, J.M.; Fournier, R.O.

1988-01-01

The December 29-30, 1985, flow test of the State 2-14 well, also known as the Salton Sea Scientific drill hole, produced fluid from a depth of 1865-1877 m at a reservoir temperature of 305????5??C. Samples were collected at five different flashing pressures. The brines are Na-Ca-K-Cl-type waters with very high metal and low SO4 and HCO3 contents. Compositions of the flashed brines were normalized relative to the 25??C densities of the solutions, and an ionic charge balance was achieved by adjusting the Na concentration. Calculated Na/K geothermometer temperatures, using equations suggested by different investigators, range from 326?? to 364??C. The Mg/K2 method gives a temperature of about 350??C, Mg/Li2 about 282??, and Na/Li 395??-418??C. -from Authors

Calibration Shots Recorded for the Salton Seismic Imaging Project, Salton Trough, California

NASA Astrophysics Data System (ADS)

Murphy, J. M.; Rymer, M. J.; Fuis, G. S.; Stock, J. M.; Goldman, M.; Sickler, R. R.; Miller, S. A.; Criley, C. J.; Ricketts, J. W.; Hole, J. A.

2009-12-01

The Salton Seismic Imaging Project (SSIP) is a collaborative venture between the U.S. Geological Survey, California Institute of Technology, and Virginia Polytechnic Institute and State University, to acquire seismic reflection/wide angle refraction data, and currently is scheduled for data acquisition in 2010. The purpose of the project is to get a detailed subsurface 3-D image of the structure of the Salton Trough (including both the Coachella and Imperial Valleys) that can be used for earthquake hazards analysis, geothermal studies, and studies of the transition from ocean-ocean to continent-continent plate-boundary. In June 2009, a series of calibration shots were detonated in the southern Imperial Valley with specific goals in mind. First, these shots were used to measure peak particle velocity and acceleration at various distances from the shots. Second, the shots were used to calibrate the propagation of energy through sediments of the Imperial Valley. Third, the shots were used to test the effects of seismic energy on buried clay drainage pipes, which are abundant throughout the irrigated parts of the Salton Trough. Fourth, we tested the ODEX drilling technique, which uses a down-hole casing hammer for a tight casing fit. Information obtained from the calibration shots will be used for final planning of the main project. The shots were located in an unused field adjacent to Hwy 7, about 6 km north of the U.S. /Mexican border (about 18 km southeast of El Centro). Three closely spaced shot points (16 meters apart) were aligned N-S and drilled to 21-m, 23.5-m, and 27-m depth. The holes were filled with 23-kg, 68-kg, and 123-kg of ammonium-nitrate explosive, respectively. Four instrument types were used to record the seismic energy - six RefTek RT130 6-channel recorders with a 3-component accelerometer and a 3-component 2-Hz velocity sensor, seven RefTek RT130 3-channel recorders with a 3-component 4.5-Hz velocity sensor, 35 Texans with a vertical component 4

Organochlorines and selenium in California night-heron and egret eggs

USGS Publications Warehouse

Ohlendorf, Harry M.; Marois, Katherine C.

1990-01-01

Exceptionally high concentrations of DDE were found in black-crowned night-heron (Nycticorax nycticorax) (geometric mean 8.62 μg g−1 wet wt.) and great egret (Casmerodius albus) (24.0 μg g−1) eggs collected from the Imperial Valley (Salton Sea), California in 1985. DDE concentrations in 14 of the 87 (16%) randomly selected night-heron eggs from six colonies (two in San Francisco Bay, three in the San Joaquin Valley, and one at Salton Sea) were higher than those associated with reduced reproductive success of night-herons (8 μg g−1). In addition, mean shell thickness of night-heron eggs collected from the San Joaquin Valley and from San Francisco Bay during 1982–1984 was significantly less than pre-DDT thickness and was negatively correlated (r=−0.50, n=75, P<0.0001) with DDE concentration. Mean selenium concentration in night-heron eggs from Salton Sea (1.10 μg g−1) was significantly higher than in eggs from three locations in the San Joaquin Valley, and in egret eggs from Salton Sea.

Detailed study of water quality, bottom sediment, and biota associated with irrigation drainage in the Salton Sea area, California, 1988-90

USGS Publications Warehouse

Setmire, J.G.; Schroeder, R.A.; Densmore, J.N.; Goodbred, S.O.; Audet, D.J.; Radke, W.R.

1993-01-01

Results of a detailed study by the National Irrigation Water-Quality Program (NIWQP), U.S. Department of the Interior, indicate that factors controlling contaminant concentrations in subsurface irrigation drainwater in the Imperial Valley are soil characteristics, hydrology, and agricultural practices. Higher contaminant concentrations commonly were associated with clayey soils, which retard the movement of irrigation water and thus increase the degree of evaporative concentration. Regression of hydrogen- and oxygen-isotope ratios in samples collected from sumps yields a linear drainwater evaporation line that extrapolates through the isotopic composition of Colorado River water, thus demonstrating that Colorado River water is the sole source of subsurface drainwater in the Imperial Valley. Ratios of selenium to chloride indicate that selenium present in subsurface drainwater throughout the Imperial Valley originates from the Colorado River. The selenium load discharged to the Salton Sea from the Alamo River, the largest contributor, is about 6.5 tons/yr. Biological sampling and analysis showed that drainwater contaminants, including selenium, boron, and DDE, are accumulating in tissues of migratory and resident birds that use food sources in the Imperial Valley and the Salton Sea. Selenium concentration in fish-eating birds, shorebirds, and the endangered Yuma clapper rail were at levels that could affect reproduction. Boron concentrations in migratory waterfowl and resident shorebirds were at levels that potentially could cause reduced growth in young. As a result of DDE contamination of food sources, waterfowl and fish-eating birds in the Imperial Valley may be experiencing reproductive impairment.

Imaging of Upper-Mantle Upwelling Beneath the Salton Trough, Southern California, by Joint Inversion of Ambient Noise Dispersion Curves and Receiver Functions

NASA Astrophysics Data System (ADS)

Klemperer, S. L.; Barak, S.

2016-12-01

We present a new 2D shear-wave velocity model of the crust and upper-mantle across the Salton Trough, southern California, obtained by jointly inverting our new dataset of receiver functions and our previously published Rayleigh-wave group-velocity model (Barak et al., G-cubed, 2015), obtained from ambient-noise tomography. Our results show an upper-mantle low-velocity zone (LVZ) with Vs ≤4.2 km/s extending from the Elsinore Fault to the Sand Hills Fault, that together bracket the full width of major San Andreas dextral motion since its inception 6 Ma b.p., and underlying the full width of low topography of the Imperial Valley and Salton Trough. The lateral extent of the LVZ is coincident with the lateral extent of an upper-mantle anisotropic region interpreted as a zone of SAF-parallel melt pockets (Barak & Klemperer, Geology, 2016). The shallowest part of the LVZ is 40 km depth, coincident with S-receiver function images. The western part of the LVZ, between the Elsinore and San Jacinto faults (the region of greatest modern dextral slip), appears to continue to significantly greater depth; but a puzzling feature of our preliminary models is that the eastern part of the LVZ, from the San Jacinto Fault to the Sand Hills Fault, appears to be underlain by more-normalvelocity upper mantle (Vs ≥ 4.5 km/s) below 75 km depth. We compare our model to the current SCEC community models CVM-H and CVM-S, and to P-wave velocity models obtained by the active-source Salton Sea Imaging Project (SSIP). The hypothesized lower-crustal low-velocity zone beneath the Salton Trough in our previous model (Barak et al., G-cubed, 2015), there interpreted as a region of partial melt, is not supported by our new modeling. Melt may be largely absent from the lower crust of the Salton trough; but appears required in the upper mantle at depths as shallow as 40 km.

Unusual dominance by desert pupfish (Cyprinodon macularius) in experimental ponds within the Salton Sea Basin

USGS Publications Warehouse

Saiki, Michael K.; Martin, Barbara A.; Anderson, Thomas W.

2011-01-01

In October 2006, months after shallow experimental ponds in the Salton Sea Basin were filled with water from the Alamo River and Salton Sea, fish were observed in several ponds, although inlets had been screened to exclude fish. During October 2007November 2009, nine surveys were conducted using baited minnow traps to document species and relative abundance of fish. Surveys yielded 3,620 fish representing five species. Desert pupfish (Cyprinodon macularius), the only native species encountered, was the most numerous and comprised >93% of the catch. Nonnative species included western mosquitofish (Gambusia affinis, 4.1%), sailfin molly (Poecilia latipinna, 2.8%), and tilapia (a mixture of hybrid Mozambique tilapia Oreochromis mossambicus ?? O. urolepis and redbelly tilapia Tilapia zillii, <0.1%). Dominance by desert pupfish, which persisted over our 2 years of study, was unusual because surveys conducted in nearby agricultural drains yielded relatively few desert pupfish.

Prevalence of neurotoxic Clostridium botulinum type C in the gastrointestinal tracts of tilapia (Oreochromis mossambicus) in the Salton Sea.

PubMed

Nol, P; Rocke, T E; Gross, K; Yuill, T M

2004-07-01

Tilapia (Oreochromis mossambicus) have been implicated as the source of type C toxin in avian botulism outbreaks in pelicans (Pelecanus erythrorhynchos, Pelecanus occidentalis californicus) at the Salton Sea in southern California (USA). We collected sick, dead, and healthy fish from various sites throughout the Sea during the summers of 1999 through 2001 and tested them for the presence of Clostridium botulinum type C cells by polymerase chain reaction targeting the C(1) neurotoxin gene. Four of 96 (4%), 57 of 664 (9%), and five of 355 (1%) tilapia tested were positive for C. botulinum type C toxin gene in 1999, 2000, and 2001, respectively. The total number of positive fish was significantly greater in 2000 than in 2001 (P<0.0001). No difference in numbers of positives was detected between sick and dead fish compared with live fish. In 2000, no significant relationships were revealed among the variables studied, such as location and date of collection.

Prevalence of neurotoxic Clostridium botulinum type C in the gastrointestinal tracts of tilapis (Oreochromis mossambicus) in the Salton Sea

USGS Publications Warehouse

Nol, P.J.; Rocke, T.E.; Gross, K.; Yuill, Thomas M.

2004-01-01

Tilapia (Oreochromis mossambicus) have been implicated as the source of type C toxin in avian botulism outbreaks in pelicans (Pelecanus erythrorhynchos, Pelecanus occidentalis californicus) at the Salton Sea in southern California (USA). We collected sick, dead, and healthy fish from various sites throughout the Sea during the summers of 1999 through 2001 and tested them for the presence of Clostridium botulinum type C cells by polymerase chain reaction targeting the C1 neurotoxin gene. Four of 96 (4%), 57 of 664 (9%), and five of 355 (1%) tilapia tested were positive for C. botulinum type C toxin gene in 1999, 2000, and 2001, respectively. The total number of positive fish was significantly greater in 2000 than in 2001 (P<0.0001). No difference in numbers of positives was detected between sick and dead fish compared with live fish. In 2000, no significant relationships were revealed among the variables studied, such as location and date of collection.

SALTON SEA SCIENTIFIC DRILLING PROJECT: SCIENTIFIC PROGRAM.

USGS Publications Warehouse

Sass, J.H.; Elders, W.A.

1986-01-01

The Salton Sea Scientific Drilling Project, was spudded on 24 October 1985, and reached a total depth of 10,564 ft. (3. 2 km) on 17 March 1986. There followed a period of logging, a flow test, and downhole scientific measurements. The scientific goals were integrated smoothly with the engineering and economic objectives of the program and the ideal of 'science driving the drill' in continental scientific drilling projects was achieved in large measure. The principal scientific goals of the project were to study the physical and chemical processes involved in an active, magmatically driven hydrothermal system. To facilitate these studies, high priority was attached to four areas of sample and data collection, namely: (1) core and cuttings, (2) formation fluids, (3) geophysical logging, and (4) downhole physical measurements, particularly temperatures and pressures.

GIS Plate Tectonic Reconstruction of the Gulf of California-Salton Trough Oblique Rift

NASA Astrophysics Data System (ADS)

Skinner, L. A.; Bennett, S. E.; Umhoefer, P. J.; Oskin, M. E.; Dorsey, R. J.; Nava, R. A.

2011-12-01

We present GIS-based plate tectonic reconstruction maps for the Gulf of California-Salton Trough oblique rift. The maps track plate boundary deformation in 2 and 1 Myr slices (6-2 Ma and 2 Ma-present) using a custom ArcGIS add-in tool to close extensional basins and restore slip on dextral faults. The tool takes a set of polygons depicting present day locations of tectonic blocks and sequentially restores displacement of their centroids along a vector specific to that time slice. Tectonic blocks are defined by faults, geology, seismic data, and bathymetry/topography. Spreading center and fault-slip rates were acquired from geologic data, cross-Gulf tie points, GPS studies, and aeromagnetic data. A recent GPS study indicated that ~92% of modern-day Pacific-North America (PAC-NAM) plate motion is localized between the Baja California microplate and North America. Relative plate motion azimuth varies from ~302° in the southern Gulf to ~314° in the Salton Trough. Baja-North America GPS rates agree remarkably with ~6 Ma geologic offsets across the Gulf and are used during reconstruction steps back to 6 Ma. In the southern Gulf, unpublished GPS data indicate that modern plate motion is partitioned between the plate boundary, Gulf-margin system, and borderland faults west of Baja California. The Alarcon and Guaymas spreading centers initiated at 2.4 Ma and 6 Ma (Lizarralde et al., 2007), respectively, while the Farallon, Pescadero, and Carmen spreading centers began between ~2-1 Ma (Lonsdale, 1989). Therefore, the 2, 4, and 6 Ma reconstruction steps include a long transtensional fault zone along much of the southern Gulf, connecting the Guaymas spreading center with either the Alarcon spreading center or East Pacific Rise. In the northern Gulf, transtensional strain initiated in coastal Sonora by ~7 Ma and migrated westward as the Gulf opened. At ~6 Ma strain migrated west into marine pull-apart basins that now lie within the eastern Gulf. Seismic reflection studies

Archaeal and bacterial communities respond differently to environmental gradients in anoxic sediments of a California hypersaline lake, the Salton Sea.

PubMed

Swan, Brandon K; Ehrhardt, Christopher J; Reifel, Kristen M; Moreno, Lilliana I; Valentine, David L

2010-02-01

Sulfidic, anoxic sediments of the moderately hypersaline Salton Sea contain gradients in salinity and carbon that potentially structure the sedimentary microbial community. We investigated the abundance, community structure, and diversity of Bacteria and Archaea along these gradients to further distinguish the ecologies of these domains outside their established physiological range. Quantitative PCR was used to enumerate 16S rRNA gene abundances of Bacteria, Archaea, and Crenarchaeota. Community structure and diversity were evaluated by terminal restriction fragment length polymorphism (T-RFLP), quantitative analysis of gene (16S rRNA) frequencies of dominant microorganisms, and cloning and sequencing of 16S rRNA. Archaea were numerically dominant at all depths and exhibited a lesser response to environmental gradients than that of Bacteria. The relative abundance of Crenarchaeota was low (0.4 to 22%) at all depths but increased with decreased carbon content and increased salinity. Salinity structured the bacterial community but exerted no significant control on archaeal community structure, which was weakly correlated with total carbon. Partial sequencing of archaeal 16S rRNA genes retrieved from three sediment depths revealed diverse communities of Euryarchaeota and Crenarchaeota, many of which were affiliated with groups previously described from marine sediments. The abundance of these groups across all depths suggests that many putative marine archaeal groups can tolerate elevated salinity (5.0 to 11.8% [wt/vol]) and persist under the anaerobic conditions present in Salton Sea sediments. The differential response of archaeal and bacterial communities to salinity and carbon patterns is consistent with the hypothesis that adaptations to energy stress and availability distinguish the ecologies of these domains.

Source properties of earthquakes near the Salton Sea triggered by the 16 October 1999 M 7.1 Hector Mine, California, earthquake

USGS Publications Warehouse

Hough, S.E.; Kanamori, H.

2002-01-01

We analyze the source properties of a sequence of triggered earthquakes that occurred near the Salton Sea in southern California in the immediate aftermath of the M 7.1 Hector Mine earthquake of 16 October 1999. The sequence produced a number of early events that were not initially located by the regional network, including two moderate earthquakes: the first within 30 sec of the P-wave arrival and a second approximately 10 minutes after the mainshock. We use available amplitude and waveform data from these events to estimate magnitudes to be approximately 4.7 and 4.4, respectively, and to obtain crude estimates of their locations. The sequence of small events following the initial M 4.7 earthquake is clustered and suggestive of a local aftershock sequence. Using both broadband TriNet data and analog data from the Southern California Seismic Network (SCSN), we also investigate the spectral characteristics of the M 4.4 event and other triggered earthquakes using empirical Green's function (EGF) analysis. We find that the source spectra of the events are consistent with expectations for tectonic (brittle shear failure) earthquakes, and infer stress drop values of 0.1 to 6 MPa for six M 2.1 to M 4.4 events. The estimated stress drop values are within the range observed for tectonic earthquakes elsewhere. They are relatively low compared to typically observed stress drop values, which is consistent with expectations for faulting in an extensional, high heat flow regime. The results therefore suggest that, at least in this case, triggered earthquakes are associated with a brittle shear failure mechanism. This further suggests that triggered earthquakes may tend to occur in geothermal-volcanic regions because shear failure occurs at, and can be triggered by, relatively low stresses in extensional regimes.

Analysis of Earthquake Source Spectra in Salton Trough

NASA Astrophysics Data System (ADS)

Chen, X.; Shearer, P. M.

2009-12-01

Previous studies of the source spectra of small earthquakes in southern California show that average Brune-type stress drops vary among different regions, with particularly low stress drops observed in the Salton Trough (Shearer et al., 2006). The Salton Trough marks the southern end of the San Andreas Fault and is prone to earthquake swarms, some of which are driven by aseismic creep events (Lohman and McGuire, 2007). In order to learn the stress state and understand the physical mechanisms of swarms and slow slip events, we analyze the source spectra of earthquakes in this region. We obtain Southern California Seismic Network (SCSN) waveforms for earthquakes from 1977 to 2009 archived at the Southern California Earthquake Center (SCEC) data center, which includes over 17,000 events. After resampling the data to a uniform 100 Hz sample rate, we compute spectra for both signal and noise windows for each seismogram, and select traces with a P-wave signal-to-noise ratio greater than 5 between 5 Hz and 15 Hz. Using selected displacement spectra, we isolate the source spectra from station terms and path effects using an empirical Green’s function approach. From the corrected source spectra, we compute corner frequencies and estimate moments and stress drops. Finally we analyze spatial and temporal variations in stress drop in the Salton Trough and compare them with studies of swarms and creep events to assess the evolution of faulting and stress in the region. References: Lohman, R. B., and J. J. McGuire (2007), Earthquake swarms driven by aseismic creep in the Salton Trough, California, J. Geophys. Res., 112, B04405, doi:10.1029/2006JB004596 Shearer, P. M., G. A. Prieto, and E. Hauksson (2006), Comprehensive analysis of earthquake source spectra in southern California, J. Geophys. Res., 111, B06303, doi:10.1029/2005JB003979.

Fault zone characteristics and basin complexity in the southern Salton Trough, California

USGS Publications Warehouse

Persaud, Patricia; Ma, Yiran; Stock, Joann M.; Hole, John A.; Fuis, Gary S.; Han, Liang

2016-01-01

Ongoing oblique slip at the Pacific–North America plate boundary in the Salton Trough produced the Imperial Valley (California, USA), a seismically active area with deformation distributed across a complex network of exposed and buried faults. To better understand the shallow crustal structure in this region and the connectivity of faults and seismicity lineaments, we used data primarily from the Salton Seismic Imaging Project to construct a three-dimensional P-wave velocity model down to 8 km depth and a velocity profile to 15 km depth, both at 1 km grid spacing. A VP = 5.65–5.85 km/s layer of possibly metamorphosed sediments within, and crystalline basement outside, the valley is locally as thick as 5 km, but is thickest and deepest in fault zones and near seismicity lineaments, suggesting a causative relationship between the low velocities and faulting. Both seismicity lineaments and surface faults control the structural architecture of the western part of the larger wedge-shaped basin, where two deep subbasins are located. We estimate basement depths, and show that high velocities at shallow depths and possible basement highs characterize the geothermal areas.

California Geothermal Forum: A Path to Increasing Geothermal Development in California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, Katherine R.

The genesis of this report was a 2016 forum in Sacramento, California, titled 'California Geothermal Forum: A Path to Increasing Geothermal Development in California.' The forum was held at the California Energy Commission's (CEC) headquarters in Sacramento, California with the primary goal being to advance the dialogues for the U.S. Department of Energy's Geothermal Technologies Office (GTO) and CEC technical research and development (R&D) focuses for future consideration. The forum convened a diverse group of stakeholders from government, industry, and research to lay out pathways for new geothermal development in California while remaining consistent with critical Federal and State conservationmore » planning efforts, particularly at the Salton Sea.« less

The effects of thick sediment upon continental breakup: seismic imaging and thermal modeling of the Salton Trough, southern California

NASA Astrophysics Data System (ADS)

Han, L.; Hole, J. A.; Lowell, R. P.; Stock, J. M.; Fuis, G. S.; Driscoll, N. W.; Kell, A. M.; Kent, G. M.; Harding, A. J.; Gonzalez-Fernandez, A.; Lázaro-Mancilla, O.

2015-12-01

Continental rifting ultimately creates a deep accommodation space for sediment. When a major river flows into a late-stage rift, thick deltaic sediment can change the thermal regime and alter the mechanisms of extension and continental breakup. The Salton Trough, the northernmost rift segment of the Gulf of California plate boundary, has experienced the same extension as the rest of the Gulf, but is filled to sea level by sediment from the Colorado River. Unlike the southern Gulf, seafloor spreading has not initiated. Instead, seismicity, high heat flow, and minor volcanoes attest to ongoing rifting of thin, transitional crust. Recently acquired controlled-source seismic refraction and wide-angle reflection data in the Salton Trough provide constraints upon crustal architecture and active rift processes. The crust in the central Salton Trough is only 17-18 km thick, with a strongly layered but relatively one-dimensional structure for ~100 km in the direction of plate motion. The upper crust includes 2-4 km of Colorado River sediment. Crystalline rock below the sediment is interpreted to be similar sediment metamorphosed by the high heat flow and geothermal activity. Meta-sediment extends to at least 9 km depth. A 4-5 km thick layer in the middle crust is either additional meta-sediment or stretched pre-existing continental crust. The lowermost 4-5 km of the crust is rift-related mafic magmatic intrusion or underplating from partial melting in the hot upper mantle. North American lithosphere in the Salton Trough has been almost or completely rifted apart. The gap has been filled by ~100 km of new transitional crust created by magmatism from below and sedimentation from above. These processes create strong lithologic, thermal, and rheologic layering. While heat flow in the rift is very high, rapid sedimentation cools the upper crust as compared to a linear geotherm. Brittle extension occurs within new meta-sedimentary rock. The lower crust, in comparison, is

Borehole-explosion and air-gun data acquired in the 2011 Salton Seismic Imaging Project (SSIP), southern California: description of the survey

USGS Publications Warehouse

Rose, Elizabeth J.; Fuis, Gary S.; Stock, Joann M.; Hole, John A.; Kell, Annie M.; Kent, Graham; Driscoll, Neal W.; Goldman, Mark; Reusch, Angela M.; Han, Liang; Sickler, Robert R.; Catchings, Rufus D.; Rymer, Michael J.; Criley, Coyn J.; Scheirer, Daniel S.; Skinner, Steven M.; Slayday-Criley, Coye J.; Murphy, Janice M.; Jensen, Edward G.; McClearn, Robert; Ferguson, Alex J.; Butcher, Lesley A.; Gardner, Max A.; Emmons, Iain; Loughran, Caleb L.; Svitek, Joseph R.; Bastien, Patrick C.; Cotton, Joseph A.; Croker, David S.; Harding, Alistair J.; Babcock, Jeffrey M.; Harder, Steven H.; Rosa, Carla M.

2013-01-01

The Imperial and Coachella Valleys are being formed by active plate-tectonic processes. From the Imperial Valley southward into the Gulf of California, plate motions are rifting the continent apart. In the Coachella Valley, the plates are sliding past one another along the San Andreas and related faults (fig. 1). These processes build the stunning landscapes of the region, but also produce damaging earthquakes. Rupture of the southern section of the San Andreas Fault (SAF), from the Coachella Valley to the Mojave Desert, is believed to be the greatest natural hazard that California will face in the near future. With an estimated magnitude between 7.2 and 8.1, such an event would result in violent shaking, loss of life, and disruption of infrastructure (freeways, aqueducts, power, petroleum, and communication lines) that might bring much of southern California to a standstill. As part of the nation’s efforts to avert a catastrophe of this magnitude, a number of projects have been undertaken to more fully understand and mitigate the effects of such an event. The Salton Seismic Imaging Project (SSIP), funded jointly by the National Science Foundation (NSF) and the U.S. Geological Survey (USGS), seeks to understand, through seismic imaging, the structure of the Earth surrounding the SAF, including the sedimentary basins on which cities are built. The principal investigators (PIs) of this collaborative project represent the USGS, Virginia Polytechnic Institute and State University (Virginia Tech), California Institute of Technology (Caltech), Scripps Institution of Oceanography (Scripps), University of Nevada, Reno (UNR), and Stanford University. SSIP will create images of underground structure and sediments in the Imperial and Coachella Valleys and adjacent mountain ranges to investigate the earthquake hazards posed to cities in this area. Importantly, the images will help determine the underground geometry of the SAF, how deep the sediments are, and how fast

Earthshots: Satellite images of environmental change – Imperial Valley, California, USA

USGS Publications Warehouse

,

2013-01-01

At the bottom of the sink lies the Salton Sea, the largest lake in California. It lacks an outlet to the ocean and lies 70 m below sea level. About 85% of the sea’s inflows come from agricultural runoff, and its waters are 37% saltier than the Pacific Ocean.

Water quality in the New River from Calexico to the Salton Sea, Imperial County, California

USGS Publications Warehouse

Setmire, James G.

1984-01-01

The New River enters the United States at Calexico, Calif., after it crosses the international boundary. Water-quality data from routine collection indicated that the New River was degraded by high organic and bacterial content. Intensive sampling for chemical and physical constituents and properties of the river was done May 9-13, 1977, to quantify the chemical composition of the water and to identify water-quality problems. Concentrations of total organic carbon in the New River at Calexico ranged from 80 to 161 milligrams per liter and dissolved organic carbon ranged from 34 to 42 milligrams per liter; the maximum chemical oxygen demand was 510 milligrams per liter. Intensive sampling for chemical and biological characteristics was done in the New River from May 1977 to June 1978 to determine the occurrence of the organic material and its effects on downstream water quality. Dissolved-oxygen concentration was measured along longitudinal profiles of the river from Calexico to the Salton Sea. A dissolved-oxygen sag downstream from the Calexico gage varied seasonally. The sag extended farther downstream and had lower concentrations of dissolved oxygen during the summer months than during the winter months. The sag of zero dissolved-oxygen concentration extended 26 miles in July 1977. In December 1976, the sag extended 20 miles but the minimum dissolved-oxygen concentration was 2.5 milligrams per liter. The greatest diel (24-hour) variation in dissolved-oxygen concentration occurred in the reach from the Calexico gage to Lyons Crossing, 8.8 miles downstream. High concentrations of organic material were detected as far as Highway 80, 19.5 miles downstream from the international boundary. Biological samples analyzed for benthic invertebrates showed that water at the Calexico and Lyons Crossing sites, nearest the international boundary, was of such poor quality that very few bottom-dwelling organisms could survive. Although the water was of poor quality at Keystone

Relationships among seismic velocity, metamorphism, and seismic and aseismic fault slip in the Salton Sea Geothermal Field region

USGS Publications Warehouse

McGuire, Jeffrey J.; Lohman, Rowena B.; Catchings, Rufus D.; Rymer, Michael J.; Goldman, Mark R.

2015-01-01

The Salton Sea Geothermal Field is one of the most geothermally and seismically active areas in California and presents an opportunity to study the effect of high-temperature metamorphism on the properties of seismogenic faults. The area includes numerous active tectonic faults that have recently been imaged with active source seismic reflection and refraction. We utilize the active source surveys, along with the abundant microseismicity data from a dense borehole seismic network, to image the 3-D variations in seismic velocity in the upper 5 km of the crust. There are strong velocity variations, up to ~30%, that correlate spatially with the distribution of shallow heat flow patterns. The combination of hydrothermal circulation and high-temperature contact metamorphism has significantly altered the shallow sandstone sedimentary layers within the geothermal field to denser, more feldspathic, rock with higher P wave velocity, as is seen in the numerous exploration wells within the field. This alteration appears to have a first-order effect on the frictional stability of shallow faults. In 2005, a large earthquake swarm and deformation event occurred. Analysis of interferometric synthetic aperture radar data and earthquake relocations indicates that the shallow aseismic fault creep that occurred in 2005 was localized on the Kalin fault system that lies just outside the region of high-temperature metamorphism. In contrast, the earthquake swarm, which includes all of the M > 4 earthquakes to have occurred within the Salton Sea Geothermal Field in the last 15 years, ruptured the Main Central Fault (MCF) system that is localized in the heart of the geothermal anomaly. The background microseismicity induced by the geothermal operations is also concentrated in the high-temperature regions in the vicinity of operational wells. However, while this microseismicity occurs over a few kilometer scale region, much of it is clustered in earthquake swarms that last from

Thermal regime of the State 2-14 well, Salton Sea Scientific Drilling Project

USGS Publications Warehouse

Sass, J.H.; Priest, S.S.; Duda, L.E.; Carson, C.C.; Hendricks, J.D.; Robison, L.C.

1988-01-01

Temperature logs were made repeatedly during breaks in drilling and both during and after flow tests in the Salton Sea Scientific Drilling Project well (State 2-14). The purpose of these logs was to assist in identifying zones of fluid loss or gain and to characterize reservoir temperatures. At the conclusion of the active phase of the project, a series of logs was begun in an attempt to establish the equilibrium temperature profile. Thermal gradients decrease from about 250 mK m-1 in the upper few hundred meters to just below 200 mK m-1 near the base of the conductive cap. Using one interpretation, thermal conductivities increase with depth (mainly because of decreasing porosity), resulting in component heat flows that agree reasonably well with the mean of about 450 mW m-2. This value agrees well with heat flow data from the shallow wells within the Salton Sea geothermal field. A second interpretation, in which measured temperature coefficients of quartz- and carbonate-rich rocks are used to correct thermal conductivity, results in lower mean conductivities that are roughly constant with depth and, consequently, systematically decreasing heat flux averaging about 350 mW m-2 below 300 m. This interpretation is consistent with the inference (from fluid inclusion studies) that the rocks in this part of the field were once several tens of degrees Celsius hotter than they are now. The age of this possible disturbance is estimated at a few thousand years. -from Authors

Understanding strain transfer and basin evolution complexities in the Salton pull-apart basin near the Southern San Andreas Fault

NASA Astrophysics Data System (ADS)

Kell, A. M.; Sahakian, V. J.; Kent, G. M.; Driscoll, N. W.; Harding, A. J.; Baskin, R. L.; Barth, M.; Hole, J. A.; Stock, J. M.; Fuis, G. S.

2015-12-01

Active source seismic data in the Salton Sea provide insight into the complexity of the pull-apart system development. Seismic reflection data combined with tomographic cross sections give constraints on the timing of basin development and strain partitioning between the two dominant dextral faults in the region; the Imperial fault to the southwest and the Southern San Andreas fault (SSAF) to the northeast. Deformation associated with this step-over appears young, having formed in the last 20-40 k.a. The complexity seen in the Salton Sea is similar to that seen in pull-apart basins worldwide. In the southern basin of the Salton Sea, a zone of transpression is noted near the southern termination of the San Andreas fault, though this stress regime quickly transitions to a region of transtension in the northern reaches of the sea. The evolution seen in the basin architecture is likely related to a transition of the SSAF dying to the north, and giving way to youthful segments of the Brawley seismic zone and Imperial fault. Stratigraphic signatures seen in seismic cross-sections also reveal a long-term component of slip to the southwest on a fault 1-2 km west of the northeastern Salton Sea shoreline. Numerous lines of evidence, including seismic reflection data, high-resolution bathymetry within the Salton Sea, and folding patterns in the Borrego Formation to the east of the sea support an assertion of a previously unmapped fault, the Salton Trough fault (STF), parallel to the SAF and just offshore within the Salton Sea. Seismic observations are seen consistently within two datasets of varying vertical resolutions, up to depths of 4-5 km, suggesting that this fault strand is much longer-lived than the evolution seen in the southern sub-basin. The existence of the STF unifies discrepancies between the onshore seismic studies and data collected within the sea. The STF likely serves as the current bounding fault to the active pull-apart system, as it aligns with the "rung

Double-diffusive convection in geothermal systems: the salton sea, California, geothermal system as a likely candidate

USGS Publications Warehouse

Fournier, R.O.

1990-01-01

Much has been published about double-diffusive convection as a mechanism for explaining variations in composition and temperature within all-liquid natural systems. However, relatively little is known about the applicability of this phenomenon within the heterogeneous rocks of currently active geothermal systems where primary porosity may control fluid flow in some places and fractures may control it in others. The main appeal of double-diffusive convection within hydrothermal systems is-that it is a mechanism that may allow efficient transfer of heat mainly by convection, while at the same time maintaining vertical and lateral salinity gradients. The Salton Sea geothermal system exhibits the following reservoir characteristics: (1) decreasing salinity and temperature from bottom to top and center toward the sides, (2) a very high heat flow from the top of the system that seems to require a major component of convective transfer of heat within the chemically stratified main reservoir, and (3) a relatively uniform density of the reservoir fluid throughout the system at all combinations of subsurface temperature, pressure, and salinity. Double-diffusive convection can account for these characteristics very nicely whereas other previously suggested models appear to account either for the thermal structure or for the salinity variations, but not both. Hydrologists, reservoir engineers, and particularly geochemists should consider the possibility and consequences of double-diffusive convection when formulating models of hydrothermal processes, and of the response of reservoirs to testing and production. ?? 1990.

Subsurface geometry of the San Andreas fault in southern California: Results from the Salton Seismic Imaging Project (SSIP) and strong ground motion expectations

USGS Publications Warehouse

Fuis, Gary S.; Bauer, Klaus; Goldman, Mark R.; Ryberg, Trond; Langenheim, Victoria; Scheirer, Daniel S.; Rymer, Michael J.; Stock, Joann M.; Hole, John A.; Catchings, Rufus D.; Graves, Robert; Aagaard, Brad T.

2017-01-01

The San Andreas fault (SAF) is one of the most studied strike‐slip faults in the world; yet its subsurface geometry is still uncertain in most locations. The Salton Seismic Imaging Project (SSIP) was undertaken to image the structure surrounding the SAF and also its subsurface geometry. We present SSIP studies at two locations in the Coachella Valley of the northern Salton trough. On our line 4, a fault‐crossing profile just north of the Salton Sea, sedimentary basin depth reaches 4 km southwest of the SAF. On our line 6, a fault‐crossing profile at the north end of the Coachella Valley, sedimentary basin depth is ∼2–3  km">∼2–3  km and centered on the central, most active trace of the SAF. Subsurface geometry of the SAF and nearby faults along these two lines is determined using a new method of seismic‐reflection imaging, combined with potential‐field studies and earthquakes. Below a 6–9 km depth range, the SAF dips ∼50°–60°">∼50°–60° NE, and above this depth range it dips more steeply. Nearby faults are also imaged in the upper 10 km, many of which dip steeply and project to mapped surface fault traces. These secondary faults may join the SAF at depths below about 10 km to form a flower‐like structure. In Appendix D, we show that rupture on a northeast‐dipping SAF, using a single plane that approximates the two dips seen in our study, produces shaking that differs from shaking calculated for the Great California ShakeOut, for which the southern SAF was modeled as vertical in most places: shorter‐period (T<1  s">T<1  s) shaking is increased locally by up to a factor of 2 on the hanging wall and is decreased locally by up to a factor of 2 on the footwall, compared to shaking calculated for a vertical fault.

The Salton Seismic Imaging Project: Seismic velocity structure of the Brawley Seismic Zone, Salton Buttes and Geothermal Field, Salton Trough, California

NASA Astrophysics Data System (ADS)

Delph, J.; Hole, J. A.; Fuis, G. S.; Stock, J. M.; Rymer, M. J.

2011-12-01

The Salton Trough is an active rift in southern California in a step-over between the plate-bounding Imperial and San Andreas Faults. In March 2011, the Salton Seismic Imaging Project (SSIP) investigated the rift's crustal structure by acquiring several seismic refraction and reflection lines. One of the densely sampled refraction lines crosses the northern-most Imperial Valley, perpendicular to the strike-slip faults and parallel to a line of small Quaternary rhyolitic volcanoes. The line crosses the obliquely extensional Brawley Seismic Zone and goes through one of the most geothermally productive areas in the United States. Well logs indicate the valley is filled by several kilometers of late Pliocene-recent lacustrine, fluvial, and shallow marine sediment. The 42-km long seismic line was comprised of eleven 110-460 kg explosive shots and receivers at a 100 m spacing. First arrival travel times were used to build a tomographic seismic velocity image of the upper crust. Velocity in the valley increases smoothly from <2 km/s to >5 km/s, indicating diagenesis and gradational metamorphism of rift sediments at very shallow depth due to an elevated geotherm. The velocity gradient is much smaller in the relatively low velocity (<6 km/s) crystalline basement comprised of recently metamorphosed sediment reaching greenschist to lower amphibolite facies. The depth of this basement is about 4-km below the aseismic region of the valley west of the Brawley Seismic Zone, but rises sharply to ~2 km depth beneath the seismically, geothermally, and volcanically active area of the Brawley Seismic Zone. The basement deepens to the northeast of the active tectonic zone and then is abruptly offset to shallower depth on the northeast side of the valley. This offset may be the subsurficial expression of a paleofault, most likely an extension of the Sand Hills Fault, which bounds the basin to the east. Basement velocity east of the fault is ~5.7 km/s, consistent with the granitic rocks

Thermal and petrologic constraints on the lower crustal melt accumulation in the Salton Sea Geothermal Field

NASA Astrophysics Data System (ADS)

Karakas, O.; Dufek, J.; Mangan, M.; Wright, H. M. N.

2014-12-01

Heat transfer in active volcanic areas is governed by complex coupling between tectonic and magmatic processes. These two processes provide unique imprints on the petrologic and thermal evolution of magma by controlling the geometry, depth, longevity, composition, and fraction of melt in the crust. The active volcanism, tectonic extension, and significantly high surface heat flow in Salton Sea Geothermal Field, CA, provides information about the dynamic heat transfer processes in its crust. The volcanism in the area is associated with tectonic extension over the last 500 ka, followed by subsidence and sedimentation at the surface level and dike emplacement in the lower crust. Although significant progress has been made describing the tectonic evolution and petrology of the erupted products of the Salton Buttes, their coupled control on the crustal heat transfer and feedback on the melt evolution remain unclear. To address these concepts, we develop a two-dimensional finite volume model and investigate the compositional and thermal evolution of the melt and crust in the Salton Sea Geothermal Field through a one-way coupled thermal model that accounts for tectonic extension, lower crustal magma emplacement, sedimentation, and subsidence. Through our simulations, we give quantitative estimates to the thermal and compositional evolution and longevity of the lower crustal melt source in the crustal section. We further compare the model results with petrologic constraints. Our thermal balance equations show that crustal melting is limited and the melt is dominated by mantle-derived material. Similarly, petrologic work on δ18O isotope ratios suggests fractional crystallization of basalt with minor crustal assimilation. In addition, we suggest scenarios for the melt fraction, composition, enthalpy release, geometry and depth of magma reservoirs, their temporal evolution, and the timescales of magmatic storage and evolution processes. These parameters provide the source

Historical Fluxes of Toxic Trace Elements and Associated Implications in the Salton Sea Basin

NASA Astrophysics Data System (ADS)

Odigie, K. O.; Hardisty, D. S.; Geraci, J. B.; Lyons, T. W.

2017-12-01

The Salton Sea is a polymictic, hypersaline lake that is predominantly sustained by wastewater and agricultural runoff from Mexico and the United States. It is a terminal lake that acts as a net sink for toxicants, which in addition to nutrients and increasing salinity, have dramatically transformed the lake over the past century. However, the impacts of these changes on the cycling and bio-accessibility of toxic elements and compounds and their associated human and environmental health implications are not well understood. This project aims to measure and model the fluxes of toxic elements, including selenium, lead, and mercury, in the lake over temporal and spatial scales by using geochemical data from the analysis of sediment cores, a pervasive salt crust, and the water column. The project also aims to elucidate the bio-accessibility and depositional environments of these elements. Preliminary results highlight two different oxygen concentration regimes in the lake: an increasingly anoxic condition in the bottom of the northern lobe and a seasonally variable oxygen deficiency in the bottom of the southern lobe. The deteriorating conditions at the lake could be exacerbated by a receding shoreline, which has already exposed several square kilometres of lake bed and is expected to continue as future inflows are diverted under the Quantification Settlement Agreement. Continued water conservation by Imperial Valley farmers and the increasing reuse of reclaimed water by Mexico are also expected to contribute to reduced inflows to the lake. Therefore, improved understanding of the cycling of toxic elements and their potential remobilization, including via wind entrainment (dust) associated with lake desiccation, will be valuable in protecting human and environmental health within the Salton Sea basin.

Temporal Variability in Seismic Velocity at the Salton Sea Geothermal Field

NASA Astrophysics Data System (ADS)

Taira, T.; Nayak, A.; Brenguier, F.

2015-12-01

We characterize the temporal variability of ambient noise wavefield and search for velocity changes associated with activities of the geothermal energy development at the Salton Sea Geothermal Field. The noise cross-correlations (NCFs) are computed for ~6 years of continuous three-component seismic data (December 2007 through January 2014) collected at 8 sites from the CalEnergy Subnetwork (EN network) with MSNoise software (Lecocq et al., 2014, SRL). All seismic data are downloaded from the Southern California Earthquake Data Center. Velocity changes (dv/v) are obtained by measuring time delay between 5-day stacks of NCFs and the reference NCF (average over the entire 6 year period). The time history of dv/v is determined by averaging dv/v measurements over all station/channel pairs (252 combinations). Our preliminary dv/v measurement suggests a gradual increase in dv/v over the 6-year period in a frequency range of 0.5-8.0 Hz. The resultant increase rate of velocity is about 0.01%/year. We also explore the frequency-dependent velocity change at the 5 different frequency bands (0.5-2.0 Hz, 0.75-3.0 Hz, 1.0-4.0 Hz, 1.5-6.0 Hz, and 2.0-8.0 Hz) and find that the level of this long-term dv/v variability is increased with increase of frequency (i.e., the highest increase rate of ~0.15%/year at the 0.5-2.0 Hz band). This result suggests that the velocity changes were mostly occurred in a depth of ~500 m assuming that the coda parts of NCFs (~10-40 s depending on station distances) are predominantly composed of scattered surface waves, with the SoCal velocity model (Dreger and Helmberger, 1993, JGR). No clear seasonal variation of dv/v is observed in the frequency band of 0.5-8.0 Hz.

In-Flight Validation of Mid and Thermal Infrared Remotely Sensed Data Using the Lake Tahoe and Salton Sea Automated Validation Sites

NASA Technical Reports Server (NTRS)

Hook, Simon J.

2008-01-01

The presentation includes an introduction, Lake Tahoe site layout and measurements, Salton Sea site layout and measurements, field instrument calibration and cross-calculations, data reduction methodology and error budgets, and example results for MODIS. Summary and conclusions are: 1) Lake Tahoe CA/NV automated validation site was established in 1999 to assess radiometric accuracy of satellite and airborne mid and thermal infrared data and products. Water surface temperatures range from 4-25C.2) Salton Sea CA automated validation site was established in 2008 to broaden range of available water surface temperatures and atmospheric water vapor test cases. Water surface temperatures range from 15-35C. 3) Sites provide all information necessary for validation every 2 mins (bulk temperature, skin temperature, air temperature, wind speed, wind direction, net radiation, relative humidity). 4) Sites have been used to validate mid and thermal infrared data and products from: ASTER, AATSR, ATSR2, MODIS-Terra, MODIS-Aqua, Landsat 5, Landsat 7, MTI, TES, MASTER, MAS. 5) Approximately 10 years of data available to help validate AVHRR.

Anthropogenic seismicity rates and operational parameters at the Salton Sea Geothermal Field.

PubMed

Brodsky, Emily E; Lajoie, Lia J

2013-08-02

Geothermal power is a growing energy source; however, efforts to increase production are tempered by concern over induced earthquakes. Although increased seismicity commonly accompanies geothermal production, induced earthquake rate cannot currently be forecast on the basis of fluid injection volumes or any other operational parameters. We show that at the Salton Sea Geothermal Field, the total volume of fluid extracted or injected tracks the long-term evolution of seismicity. After correcting for the aftershock rate, the net fluid volume (extracted-injected) provides the best correlation with seismicity in recent years. We model the background earthquake rate with a linear combination of injection and net production rates that allows us to track the secular development of the field as the number of earthquakes per fluid volume injected decreases over time.

The application of active-source seismic imaging techniques to transtensional problems the Walker Lane and Salton Trough

NASA Astrophysics Data System (ADS)

Kell, Anna Marie

The plate margin in the western United States is an active tectonic region that contains the integrated deformation between the North American and Pacific plates. Nearly focused plate motion between the North American and Pacific plates within the northern Gulf of California gives way north of the Salton Trough to more diffuse deformation. In particular a large fraction of the slip along the southernmost San Andreas fault ultimately bleeds eastward, including about 20% of the total plate motion budget that finds its way through the transtensional Walker Lane Deformation Belt just east of the Sierra Nevada mountain range. Fault-bounded ranges combined with intervening low-lying basins characterize this region; the down-dropped features are often filled with water, which present opportunities for seismic imaging at unprecedented scales. Here I present active-source seismic imaging from the Salton Sea and Walker Lane Deformation Belt, including both marine applications in lakes and shallow seas, and more conventional land-based techniques along the Carson range front. The complex fault network beneath the Salton Trough in eastern California is the on-land continuation of the Gulf of California rift system, where North American-Pacific plate motion is accommodated by a series of long transform faults, separated by small pull-apart, transtensional basins; the right-lateral San Andreas fault bounds this system to the north where it carries, on average, about 50% of total plate motion. The Salton Sea resides within the most youthful and northerly "spreading center" in this several thousand-kilometer-long rift system. The Sea provides an ideal environment for the use of high-data-density marine seismic techniques. Two active-source seismic campaigns in 2010 and 2011 show progression of the development of the Salton pull-apart sub-basin and the northerly propagation of the Imperial-San Andreas system through time at varying resolutions. High fidelity seismic imagery

Southern San Andreas Fault Slip History Refined Using Pliocene Colorado River Deposits in the Western Salton Trough

NASA Astrophysics Data System (ADS)

Dorsey, R. J.; Bennett, S. E. K.; Housen, B. A.

2016-12-01

Tectonic reconstructions of Pacific-North America plate motion in the Salton Trough region (Bennett et al., 2016) are constrained by: (1) late Miocene volcanic rocks that record 255 +/-10 km of transform offset across the northern Gulf of California since 6 Ma (average 42 mm/yr; Oskin and Stock, 2003); and (2) GPS data that show modern rates of 50-52 mm/yr between Pacific and North America plates, and 46-48 mm/yr between Baja California (BC) and North America (NAM) (Plattner et al., 2007). New data from Pliocene Colorado River deposits in the Salton Trough provide an important additional constraint on the geologic history of slip on the southern San Andreas Fault (SAF). The Arroyo Diablo Formation (ADF) in the San Felipe Hills SW of the Salton Sea contains abundant cross-bedded channel sandstones deformed in the dextral Clark fault zone. The ADF ranges in age from 4.3 to 2.8 Ma in the Fish Creek-Vallecito basin, and in the Borrego Badlands its upper contact with the Borrego Formation is 2.9 Ma based on our new magnetostratigraphy. ADF paleocurrent data from a 20-km wide, NW-oriented belt near Salton City record overall transport to the SW (corrected for bedding dip, N=165), with directions ranging from NW to SE. Spatial domain analysis reveals radial divergence of paleoflow to the: W and NW in the NW domain; SW in the central domain; and S in the SE domain. Data near Borrego Sink, which restores to south of Salton City after removing offset on the San Jacinto fault zone, show overall transport to the SE. Pliocene patterns of radial paleoflow divergence strongly resemble downstream bifurcation of fluvial distributary channels on the modern Colorado River delta SW of Yuma, and indicate that Salton City has translated 120-130 km NW along the SAF since 3 Ma. We propose a model in which post-6 Ma BC-NAM relative motion gradually accelerated to 50 mm/yr by 4 Ma, continued at 50 mm/yr from 4-1 Ma, and decreased to 46 mm/yr from 1-0 Ma (split equally between the SAF and

Apollo 9 Mission image - S0-65 Multispectral Photography - California and Mexico

NASA Image and Video Library

1969-03-12

AS09-26A-3799A (12 March 1969) --- Color infrared photograph of the Salton Sea and Imperial Valley area of Southern California as seen from the Apollo 9 spacecraft. This picture was taken as a part of the SO-65 Multispectral Terrain Photography Experiment. On the eastern edge of the picture are the Colorado River and a small portion of Arizona. Yuma, Arizona, is at the bottom right corner. The cities of El Centro, California, and Mexicali, Mexico, are at the bottom center.

Does the West Salton Detachment extend through San Gorgonio Pass, southern California?

NASA Astrophysics Data System (ADS)

Matti, J. C.; Langenheim, V. E.

2008-12-01

Rift-related extension and low-angle crustal detachment are key structural elements of the late Cenozoic southern San Andreas Fault system, as manifested by the West Salton Detachment (WSD). The most northwestern exposure of the WSD is in the Santa Rosa Mts (SRM), where the Zosel Fault bottoms a hangingwall sequence of upper Cenozoic marine and terrestrial sedimentary deposits that include stratigraphic units well known throughout the Salton Trough region. We have used geologic and geophysical data to investigate the distribution of the WSD system in the northern Salton Trough, including its possible extension into and beyond San Gorgonio Pass. Although the WSD is not exposed north of the SRM, late Miocene marine and terrigenous sedimentary rocks at Garnet Hill probably are hangingwall deposits squeezed up within the San Andreas Fault zone. West of Garnet Hill lie San Gorgonio Pass (SGP) and the 3 km-high northern escarpment of the San Jacinto Mountains (SJM). In SGP, upper Cenozoic sedimentary rocks south of the Banning strand of the San Gabriel Fault include the marine Imperial Formation and associated terrestrial deposits, a sequence similar to that in the WSD hangingwall throughout the greater Salton Trough region. We propose that the WSD originally extended from the NW head of Coachella Valley west into SGP, where the detachment may form the base of the Cenozoic marine and terrestrial sedimentary sequence. The WSD probably continues west beyond SGP, with extensional translation decreasing until the detachment intersects the Banning Fault near Calimesa. There, we propose that the WSD underlies a subsurface sedimentary package north of the San Timoteo badlands and south of the Banning Fault that a gravity low suggests is 2 km thick, and that reportedly contains marine sediment penetrated in boreholes. When ~44 km of right-slip is restored on the Banning Fault (Matti and Morton, 1993), the Calimesa low restores opposite a similar low in the northwestern Coachella

Occurrence of wide-chain Ca-pyriboles as primary crystals in the Salton Sea Geothermal Field, California, USA

NASA Astrophysics Data System (ADS)

Yau, Yu-Chyi; Peacor, Donald R.; Essene, Eric J.

1986-09-01

Amphiboles and pyroxenes occurring in the Salton Sea Geothermal Field were found to contain coherent intergrowths of chain silicates with other than double and single chain widths by using transmission and analytical electron microscopy. Both occur in the biotite zone at the temperature (depth) interval of 310° C (1,060 m) to 330° C (1,547m) which approximately corresponds to temperatures of the greenschist facies. The amphiboles occur as euhedral fibrous crystals occupying void space and are composed primarily of irregularly alternating (010) slabs of double or triple chains, with rare quadruple and quintuple chains. Primary crystallization from solution results in euhedral crystals. Clinopyroxenes formed mainly as a porefilling cement and subordinately as prismatic crystals coexisting with fibrous amphiboles. Fine lamellae of double and triple chains are irregularly intercalated with pyroxene. AEM analyses yield formulae (Ca1.8Mg2.9Fe1.9Mn0.1) Si8O21.8(OH)1.8 (310° C) and (Ca2.0Fe2.5Mg2.3) Si8O21.8 (OH)2.0 (330° C) for amphiboles and (Ca1.1Fe0.6Mg0.3) Si2O6 for clinopyroxene. Thermodynamic calculations at Pfluid=100 bar of equilibrium reactions of (1) 3 chlorite +10 calcite + 21 quartz = 3 actinolite + 2 clinozoisite + 8 H2O + 10 CO2 and (2) actinolite+ 3 calcite+ 2 quartz = 5 clinopyroxene + H2O + 3 CO2 using Mg-end member phases indicate that formation of amphibole and pyroxene require very water-rich conditions (X_{CO_2 } < 0.06) at temperatures below 330° C.

Earth Observations

NASA Image and Video Library

2013-06-21

ISS036-E-011034 (21 June 2013) --- The Salton Trough is featured in this image photographed by an Expedition 36 crew member on the International Space Station. The Imperial and Coachella Valleys of southern California – and the corresponding Mexicali Valley and Colorado River Delta in Mexico – are part of the Salton Trough, a large geologic structure known to geologists as a graben or rift valley that extends into the Gulf of California. The trough is a geologically complex zone formed by interaction of the San Andreas transform fault system that is, broadly speaking, moving southern California towards Alaska; and the northward motion of the Gulf of California segment of the East Pacific Rise that continues to widen the Gulf of California by sea-floor spreading. According to scientists, sediments deposited by the Colorado River have been filling the northern rift valley (the Salton Trough) for the past several million years, excluding the waters of the Gulf of California and providing a fertile environment – together with irrigation—for the development of extensive agriculture in the region (visible as green and yellow-brown fields at center). The Salton Sea, a favorite landmark of astronauts in low Earth orbit, was formed by an irrigation canal rupture in 1905, and today is sustained by agricultural runoff water. A wide array of varying landforms and land uses in the Salton Trough are visible from space. In addition to the agricultural fields and Salton Sea, easily visible metropolitan areas include Yuma, AZ (lower left); Mexicali, Baja California, Mexico (center); and the San Diego-Tijuana conurbation on the Pacific Coast (right). The approximately 72-kilometer-long Algodones Dunefield is visible at lower left.

Character and Implications of a Newly Identified Creeping Strand of the San Andreas fault NE of Salton Sea, Southern California

NASA Astrophysics Data System (ADS)

Janecke, S. U.; Markowski, D.

2015-12-01

The overdue earthquake on the Coachella section, San Andreas fault (SAF), the model ShakeOut earthquake, and the conflict between cross-fault models involving the Extra fault array and mapped shortening in the Durmid Hill area motivate new analyses at the southern SAF tip. Geologic mapping, LiDAR, seismic reflection, magnetic and gravity datasets, and aerial photography confirm the existence of the East Shoreline strand (ESS) of the SAF southwest of the main trace of the SAF. We mapped the 15 km long ESS, in a band northeast side of the Salton Sea. Other data suggest that the ESS continues N to the latitude of the Mecca Hills, and is >35 km long. The ESS cuts and folds upper Holocene beds and appears to creep, based on discovery of large NW-striking cracks in modern beach deposits. The two traces of the SAF are parallel and ~0.5 to ~2.5 km apart. Groups of east, SE, and ENE-striking strike-slip cross-faults connect the master dextral faults of the SAF. There are few sinistral-normal faults that could be part of the Extra fault array. The 1-km wide ESS contains short, discontinuous traces of NW-striking dextral-oblique faults. These en-echelon faults bound steeply dipping Pleistocene beds, cut out section, parallel tight NW-trending folds, and produced growth folds. Beds commonly dip toward the ESS on both sides, in accord with persistent NE-SW shortening across the ESS. The dispersed fault-fold structural style of the ESS is due to decollements in faulted mud-rich Pliocene to Holocene sediment and ramps and flats along the strike-slip faults. A sheared ladder-like geometric model of the two master dextral strands of the SAF and their intervening cross-faults, best explains the field relationships and geophysical datasets. Contraction across >40 km2 of the southernmost SAF zone in the Durmid Hills suggest that interaction of active structures in the SAF zone may inhibit the nucleation of large earthquakes in this region. The ESS may cross the northern Coachella

Diagnosis and seroprevalence of leptospirosis in California sea lions from coastal California.

PubMed

Colagross-Schouten, Angela M; Mazet, Jonna A K; Gulland, Frances M D; Miller, Melissa A; Hietala, Sharon

2002-01-01

The sensitivity and specificity of the microscopic agglutination test (MAT) as a method for detection of exposure to Leptospira spp. in California sea lions (Zalophus californianus) were determined. Sera came from individuals that demonstrated clinical signs of renal disease, had lesions suggestive of leptospirosis at necropsy, and had visible leptospires in silver stained kidney sections as positive controls. Sera from unexposed captive individuals were used as negative controls. The test was 100% sensitive at 1:3,200 for confirming renal infection and 100% specific at negative < 1:100 for detection of Leptospira interrogans scrovar pomona antibodies by MAT in California sea lions. Leptospira interrogans serovar pomona was used as a screening serovar because it has been isolated previously from the kidneys and placentas of California sea lions, and there appears to be cross-reactivity between serovar pomona and other serovars. Sera from 225 free-ranging California sea lions presented to one of three participating California (USA) coastal marine mammal rehabilitation centers in 1996 were then evaluated for antibodies to serovar pomona using the MAT. The overall seroprevalence was 38.2% (86/225), although the prevalence varied among locations from 100% (38/38) in animals at the Marine Mammal Care Center (Fort MacArthur, California, USA) to 0% (0/14) at SeaWorld California (San Diego, California). At The Marine Mammal Center (Sausalito, California) [prevalence 27.8% (48/173)], the majority of seropositive animals were subadults and adults, and males were 4.7 times more likely to be seropositive to serovar pomona than females. When combining results from all three centers, subadult and adult animals were more likely to be seropositive than pups and juvenile sea lions, and the highest proportion of seropositive animals presented during the autumn months. Serum elevations of blood urea nitrogen, creatinine, phosphorus, and/or calcium were associated with seropositivity

Uncinariasis in northern fur seal and California sea lion pups from California.

PubMed

Lyons, E T; DeLong, R L; Melin, S R; Tolliver, S C

1997-10-01

Northern fur seal (Callorhinus ursinus) (n = 25) and California sea lion (Zalophus californianus) (n = 53) pups, found dead on rookeries on San Miguel Island (California, USA), were examined for adult Uncinaria spp. Prevalence of these nematodes was 96% in fur seal pups and 100% in sea lion pups. Mean intensity of Uncinaria spp. per infected pup was 643 in fur seals and 1,284 in sea lions. Eggs of Uncinaria spp. from dead sea lion pups underwent embryonation in an incubator; development to the free-living third stage larva occurred within the egg. This study provided some specific information on hookworm infections in northern fur seal and California sea lion pups on San Miguel Island. High prevalence rate of Uncinaria spp. in both species of pinnipeds was documented and much higher numbers (2X) of hookworms were present in sea lion than fur seal pups.

Pesticides in Water and Suspended Sediment of the Alamo and New Rivers, Imperial Valley/Salton Sea Basin, California, 2006-2007

USGS Publications Warehouse

Orlando, James L.; Smalling, Kelly L.; Kuivila, Kathryn

2008-01-01

Water and suspended-sediment samples were collected at eight sites on the Alamo and New Rivers in the Imperial Valley/Salton Sea Basin of California and analyzed for both current-use and organochlorine pesticides by the U.S. Geological Survey. Samples were collected in the fall of 2006 and spring of 2007, corresponding to the seasons of greatest pesticide use in the basin. Large-volume water samples (up to 650 liters) were collected at each site and processed using a flow-through centrifuge to isolate suspended sediments. One-liter water samples were collected from the effluent of the centrifuge for the analysis of dissolved pesticides. Additional samples were collected for analysis of dissolved organic carbon and for suspended-sediment concentrations. Water samples were analyzed for a suite of 61 current-use and organochlorine pesticides using gas chromatography/mass spectrometry. A total of 25 pesticides were detected in the water samples, with seven pesticides detected in more than half of the samples. Dissolved concentrations of pesticides observed in this study ranged from below their respective method detection limits to 8,940 nanograms per liter (EPTC). The most frequently detected compounds in the water samples were chlorpyrifos, DCPA, EPTC, and trifluralin, which were observed in more than 75 percent of the samples. The maximum concentrations of most pesticides were detected in samples from the Alamo River. Maximum dissolved concentrations of carbofuran, chlorpyrifos, diazinon, and malathion exceeded aquatic life benchmarks established by the U.S. Environmental Protection Agency for these pesticides. Suspended sediments were analyzed for 87 current-use and organochlorine pesticides using microwave-assisted extraction, gel permeation chromatography for sulfur removal, and either carbon/alumina stacked solid-phase extraction cartridges or deactivated Florisil for removal of matrix interferences. Twenty current-use pesticides were detected in the suspended

Experimental evaluation of atmospheric effects on radiometric measurements using the EREP of Skylab. [Salton Sea and Great Salt Lake

NASA Technical Reports Server (NTRS)

Chang, D. T. (Principal Investigator); Isaacs, R. G.

1975-01-01

The author has identified the following significant results. Test sites were located near the Great Salt Lake and the Salton Sea. Calculations were performed for a set of atmospheric models corresponding to the test sites, in addition to standard models for summer and winter midlatitude atmospheres with respective integrated water vapor amount of 2.4 g/sq cm and 0.9 g/sq cm. Each atmosphere was found to contain an average amount of continental aerosol. Computations were valid for high solar elevation angles. Atmospheric attenuation quantities were computed in addition to simulated EREP S192 radiances.

Bioindicators from Mosquitofish (Gambusia affinis) Sampled from the Imperial Valley in Southern California

USGS Publications Warehouse

Jenkins, Jill A.; Draugelis-Dale, Rassa O.

2006-01-01

The Sonny Bono Salton Sea National Wildlife Refuge (SSNWR) is located 64 km north of the Mexican border at the southern end of the Salton Sea in California's Imperial Valley. Freshwater ponds and managed habitats at the SSNWR, Calipatria, Calif. are supplied with Colorado River water that carries compounds from upstream sources. Components include municipal and industrial discharges, agricultural drainage, and sewage plant inputs. Aquatic animals in these ecosystems are continuously exposed to multiple constituents, several of which have been demonstrated to be associated with hormonal disturbances. We investigated possible endocrine impacts to fish in the Imperial Valley, Calif., by addressing the null hypothesis that aquatic species in impacted sites did not exhibit evidence of endocrine disruption as compared with those from nonimpacted sites. The results presented are intended to provide managers with science-based information and interpretations about the condition of the animals in their ecosystems for the minimization of potential adverse effects to trust fish and wildlife resources and for the maximization of available water resources.

3-D Velocity Model of the Coachella Valley, Southern California Based on Explosive Shots from the Salton Seismic Imaging Project

NASA Astrophysics Data System (ADS)

Persaud, P.; Stock, J. M.; Fuis, G. S.; Hole, J. A.; Goldman, M.; Scheirer, D. S.

2014-12-01

We have analyzed explosive shot data from the 2011 Salton Seismic Imaging Project (SSIP) across a 2-D seismic array and 5 profiles in the Coachella Valley to produce a 3-D P-wave velocity model that will be used in calculations of strong ground shaking. Accurate maps of seismicity and active faults rely both on detailed geological field mapping and a suitable velocity model to accurately locate earthquakes. Adjoint tomography of an older version of the SCEC 3-D velocity model shows that crustal heterogeneities strongly influence seismic wave propagation from moderate earthquakes (Tape et al., 2010). These authors improve the crustal model and subsequently simulate the details of ground motion at periods of 2 s and longer for hundreds of ray paths. Even with improvements such as the above, the current SCEC velocity model for the Salton Trough does not provide a match of the timing or waveforms of the horizontal S-wave motions, which Wei et al. (2013) interpret as caused by inaccuracies in the shallow velocity structure. They effectively demonstrate that the inclusion of shallow basin structure improves the fit in both travel times and waveforms. Our velocity model benefits from the inclusion of known location and times of a subset of 126 shots detonated over a 3-week period during the SSIP. This results in an improved velocity model particularly in the shallow crust. In addition, one of the main challenges in developing 3-D velocity models is an uneven stations-source distribution. To better overcome this challenge, we also include the first arrival times of the SSIP shots at the more widely spaced Southern California Seismic Network (SCSN) in our inversion, since the layout of the SSIP is complementary to the SCSN. References: Tape, C., et al., 2010, Seismic tomography of the Southern California crust based on spectral-element and adjoint methods: Geophysical Journal International, v. 180, no. 1, p. 433-462. Wei, S., et al., 2013, Complementary slip distributions

Field, Laboratory and Imaging spectroscopic Analysis of Landslide, Debris Flow and Flood Hazards in Lacustrine, Aeolian and Alluvial Fan Deposits Surrounding the Salton Sea, Southern California

NASA Astrophysics Data System (ADS)

Hubbard, B. E.; Hooper, D. M.; Mars, J. C.

2015-12-01

High resolution satellite imagery, field spectral measurements using a portable ASD spectrometer, and 2013 hyperspectral AVIRIS imagery were used to evaluate the age of the Martinez Mountain Landslide (MML) near the Salton Sea, in order to determine the relative ages of adjacent alluvial fan surfaces and the potential for additional landslides, debris flows, and floods. The Salton Sea (SS) occupies a pluvial lake basin, with ancient shorelines ranging from 81 meters to 113 meters above the modern lake level. The highest shoreline overlaps the toe of the 0.24 - 0.38 km3 MML deposit derived from hydrothermally altered granites exposed near the summit of Martinez Mountain. The MML was originally believed to be of early Holocene age. However, AVIRIS mineral maps show abundant desert varnish on the top and toe of the landslide. Desert varnish can provide a means of relative dating of alluvial fan (AF) or landslide surfaces, as it accumulates at determinable rates over time. Based on the 1) highest levels of desert varnish accumulation mapped within the basin, 2) abundant evaporite playa minerals on top of the toe of the landslide, and 3) the highest shoreline of the ancestral lake overtopping the toe of the landslide with gastropod and bivalve shells, we conclude that the MML predates the oldest alluvial fan terraces and lake sediments exposed in the Coachella and Imperial valleys and must be older than early Holocene (i.e. Late Pleistocene?). Thus, the MML landslide has the potential to be used as a spectral endmember for desert varnish thickness and thus proxy for age discrimination of active AF washes versus desert pavements. Given the older age of the MML landslide and low water levels in the modern SS, the risk from future rockslides of this size and related seiches is rather low. However, catastrophic floods and debris flows do occur along the most active AF channels; and the aftermath of such flows can be identified spectrally by montmorillonite crusts forming in

Groundwater quality in Coachella Valley, California

USGS Publications Warehouse

Dawson, Barbara J. Milby; Belitz, Kenneth

2012-01-01

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Coachella Valley is one of the study areas being evaluated. The Coachella study area is approximately 820 square miles (2,124 square kilometers) and includes the Coachella Valley groundwater basin (California Department of Water Resources, 2003). Coachella Valley has an arid climate, with average annual rainfall of about 6 inches (15 centimeters). The runoff from the surrounding mountains drains to rivers that flow east and south out of the study area to the Salton Sea. Land use in the study area is approximately 67 percent (%) natural, 21% agricultural, and 12% urban. The primary natural land cover is shrubland. The largest urban areas are the cities of Indio and Palm Springs (2010 populations of 76,000 and 44,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Coachella Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Coachella Valley are completed to depths between 490 and 900 feet (149 to 274 meters), consist of solid casing from the land surface to a depth of 260 to 510 feet (79 to 155 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation. The primary sources of discharge are pumping wells, evapotranspiration, and underflow to

Comparative Study of Earthquake Clustering in Relation to Hydraulic Activities at Geothermal Fields in California

NASA Astrophysics Data System (ADS)

Martínez-Garzón, P.; Zaliapin, I. V.; Ben-Zion, Y.; Kwiatek, G.; Bohnhoff, M.

2017-12-01

We investigate earthquake clustering properties from three geothermal reservoirs to clarify how earthquake patterns respond to hydraulic activities. We process ≈ 9 years from four datasets corresponding to the Geysers (both the entire field and a local subset), Coso and Salton Sea geothermal fields, California. For each, the completeness magnitude, b-value and fractal dimension are calculated and used to identify seismicity clusters using the nearest-neighbor approach of Zaliapin and Ben-Zion [2013a, 2013b]. Estimations of temporal evolution of different clustering properties in relation to hydraulic parameters point to different responses of earthquake dynamics to hydraulic operations in each case study. The clustering at the Geysers at local scale and Salton Sea are most and least affected by hydraulic activities, respectively. The response of the earthquake clustering from different datasets to the hydraulic activities may reflect the regional seismo-tectonic complexity as well as the dimension of the geothermal activities performed (e.g. number of active wells and superposition of injection + production activities).Two clustering properties significantly respond to hydraulic changes across all datasets: the background rates and the proportion of clusters consisting of a single event. Background rates are larger at the Geysers and Coso during high injection-production periods, while the opposite holds for the Salton Sea. This possibly reflects the different physical mechanisms controlling seismicity at each geothermal field. Additionally, a lower proportion of singles is found during time periods with higher injection-production rates. This may reflect decreasing effective stress in areas subjected to higher pore pressure and larger earthquake triggering by stress transfer.

Preface

USGS Publications Warehouse

Friend, M.

2002-01-01

This issue of Hydrobiologia brings together a series of papers resulting from an intensified effort to describe the current status of the physical and biological conditions present at California's Salton Sea. Most of the studies were contract investigations that were part of a project initiated in January 1998 to pursue the improvement of environmental conditions at the Salton Sea. The remainder are independent investigations resulting in information of importance for the Salton Sea Restoration Project. The information provided by those investigations resulting in information of importance for the Salton Sea Restoration Project. The information provided by those investigations is the most holistic assembly of scientific knowledge about the Salton Sea ever brought together in a single publication. The resulting findings provide an important foundation of knowledge for what has been stated to be '. . . one of the worlds' most dynamic salt lakes . . .' (Hart et al., 1998). We hope this publication will serve as a catalyst to stimulate additional scientific investigations that will further enhance understanding of the dynamics of this unique ecosystem. The purpose for these introductory comments is to place the scientific investigations reported on and the Salton Sea Restoration Project in context and entities, and to one another.

Chang-Diaz's EMU lower torso (legs) suspended against an Earth view during STS-111 UF-2 EVA 2

NASA Image and Video Library

2002-06-12

STS111-E-5224 (12 June 2002) --- Southern California’s Salton Sea is routinely a prominent visual for astronauts passing overhead on the shuttle or International Space Station (ISS). This large lake, photographed from the station while docked to the Space Shuttle Endeavour by one of the STS-111 crew members, supports the rich agricultural fields of the Imperial, Coachella and Mexicali Valleys in the California and Mexico desert. According to geologists, the Salton Sea formed by accident in 1905 when an irrigation canal ruptured, allowing the Colorado River to flood the Salton Basin. Today the Sea performs an important function as the sink for agricultural runoff. Water levels are maintained by the runoff from the surrounding agricultural valleys. The Salton Sea salinity is high -- nearly 1/4 saltier than ocean water --but it remains an important stopover point for migratory water birds, including several endangered species. Scientists also noted that the region experiences several environmental problems. The recent increased demands for the limited Colorado River water, the scientists point out, threatens the amount of water allowed to flow into the Salton Sea, and increased salinity with decreased water levels could trigger several regional environmental crises. The agricultural flow into the Sea includes nutrients and agricultural by-products, increasing the productivity and likelihood of algae blooms. This image shows either a bloom, or suspended sediment (usually highly organic) in the water that has been stirred up by winds.

The Fecal Viral Flora of California Sea Lions▿†

PubMed Central

Li, Linlin; Shan, Tongling; Wang, Chunlin; Côté, Colette; Kolman, John; Onions, David; Gulland, Frances M. D.; Delwart, Eric

2011-01-01

California sea lions are one of the major marine mammal species along the Pacific coast of North America. Sea lions are susceptible to a wide variety of viruses, some of which can be transmitted to or from terrestrial mammals. Using an unbiased viral metagenomic approach, we surveyed the fecal virome in California sea lions of different ages and health statuses. Averages of 1.6 and 2.5 distinct mammalian viral species were shed by pups and juvenile sea lions, respectively. Previously undescribed mammalian viruses from four RNA virus families (Astroviridae, Picornaviridae, Caliciviridae, and Reoviridae) and one DNA virus family (Parvoviridae) were characterized. The first complete or partial genomes of sapeloviruses, sapoviruses, noroviruses, and bocavirus in marine mammals are reported. Astroviruses and bocaviruses showed the highest prevalence and abundance in California sea lion feces. The diversity of bacteriophages was higher in unweaned sea lion pups than in juveniles and animals in rehabilitation, where the phage community consisted largely of phages related to the family Microviridae. This study increases our understanding of the viral diversity in marine mammals, highlights the high rate of enteric viral infections in these highly social carnivores, and may be used as a baseline viral survey for comparison with samples from California sea lions during unexplained disease outbreaks. PMID:21795334

Absence of remote earthquake triggering within the Coso and Salton Sea geothermal production fields

NASA Astrophysics Data System (ADS)

Zhang, Qiong; Lin, Guoqing; Zhan, Zhongwen; Chen, Xiaowei; Qin, Yan; Wdowinski, Shimon

2017-01-01

Geothermal areas are long recognized to be susceptible to remote earthquake triggering, probably due to the high seismicity rates and presence of geothermal fluids. However, anthropogenic injection and extraction activity may alter the stress state and fluid flow within the geothermal fields. Here we examine the remote triggering phenomena in the Coso geothermal field and its surrounding areas to assess possible anthropogenic effects. We find that triggered earthquakes are absent within the geothermal field but occur in the surrounding areas. Similar observation is also found in the Salton Sea geothermal field. We hypothesize that continuous geothermal operation has eliminated any significant differential pore pressure between fractures inside the geothermal field through flushing geothermal precipitations and sediments out of clogged fractures. To test this hypothesis, we analyze the pore-pressure-driven earthquake swarms, and they are found to occur outside or on the periphery of the geothermal production field. Therefore, our results suggest that the geothermal operation has changed the subsurface fracture network, and differential pore pressure is the primary controlling factor of remote triggering in geothermal fields.

Apollo 9 Mission image - Earth limb over California with S.L.A. in distance

NASA Image and Video Library

1969-03-03

Oblique Earth Observation taken by the Apollo 9 crew. View is of California including: Sanata Barbara, Los Angeles, San Diego, Santa Rosa, San Miguel, and Santa Cruz Islands, Santa Barbara Channel, Salton Sea and the Service Module (SM) Lunar Module (LM) adapter (S.L.A.) in the distance. Film magazine was A,film type was SO-368 Ektachrome with 0.460 - 0.710 micrometers film / filter transmittance response and haze filter, 80mm lens. Latitude was 32.55 N by Longitude 119.58 W, Altitude miles were 106 and cloud cover was 25%.

Discovering new events beyond the catalogue—application of empirical matched field processing to Salton Sea geothermal field seismicity

DOE PAGES

Wang, Jingbo; Templeton, Dennise C.; Harris, David B.

2015-07-30

Using empirical matched field processing (MFP), we compare 4 yr of continuous seismic data to a set of 195 master templates from within an active geothermal field and identify over 140 per cent more events than were identified using traditional detection and location techniques alone. In managed underground reservoirs, a substantial fraction of seismic events can be excluded from the official catalogue due to an inability to clearly identify seismic-phase onsets. Empirical MFP can improve the effectiveness of current seismic detection and location methodologies by using conventionally located events with higher signal-to-noise ratios as master events to define wavefield templatesmore » that could then be used to map normally discarded indistinct seismicity. Since MFP does not require picking, it can be carried out automatically and rapidly once suitable templates are defined. In this application, we extend MFP by constructing local-distance empirical master templates using Southern California Earthquake Data Center archived waveform data of events originating within the Salton Sea Geothermal Field. We compare the empirical templates to continuous seismic data collected between 1 January 2008 and 31 December 2011. The empirical MFP method successfully identifies 6249 additional events, while the original catalogue reported 4352 events. The majority of these new events are lower-magnitude events with magnitudes between M0.2–M0.8. Here, the increased spatial-temporal resolution of the microseismicity map within the geothermal field illustrates how empirical MFP, when combined with conventional methods, can significantly improve seismic network detection capabilities, which can aid in long-term sustainability and monitoring of managed underground reservoirs.« less

Final Report: Baseline Selenium Monitoring of Agricultural Drains Operated by the Imperial Irrigation District in the Salton Sea Basin, California

USGS Publications Warehouse

Saiki, Michael K.; Martin, Barbara A.; May, Thomas W.

2010-01-01

This report summarizes comprehensive findings from a 4-year-long field investigation to document baseline environmental conditions in 29 agricultural drains and ponds operated by the Imperial Irrigation District along the southern border of the Salton Sea. Routine water-quality collections and fish community assessments were conducted on as many as 16 sampling dates at roughly quarterly intervals from July 2005 to April 2009. The water-quality measurements included total suspended solids and total (particulate plus dissolved) selenium. With one exception, fish were surveyed with baited minnow traps at quarterly intervals during the same time period. However, in July 2007, fish surveys were not conducted because we lacked permission from the California Department of Fish and Game for incidental take of desert pupfish (Cyprinodon macularius), an endangered species. During April and October 2006-08, water samples also were collected from seven intensively monitored drains (which were selected from the 29 total drains) for measurement of particulate and dissolved selenium, including inorganic and organic fractions. In addition, sediment, aquatic food chain matrices [particulate organic detritus, filamentous algae, net plankton, and midge (chironomid) larvae], and two fish species (western mosquitofish, Gambusia affinis; and sailfin molly, Poecilia latipinna) were sampled from the seven drains for measurement of total selenium concentrations. The mosquitofish and mollies were intended to serve as surrogates for pupfish, which we were not permitted to sacrifice for selenium determinations. Water quality (temperature, dissolved oxygen, pH, specific conductance, and turbidity) values were typical of surface waters in a hot, arid climate. A few drains exhibited brackish, near-anoxic conditions, especially during summer and fall when water temperatures occasionally exceeded 30 degrees Celsius. Total selenium concentrations in water were directly correlated with salinity and

The Origin of High-angle Dip-slip Earthquakes at Geothermal Fields in California

NASA Astrophysics Data System (ADS)

Barbour, A. J.; Schoenball, M.; Martínez-Garzón, P.; Kwiatek, G.

2016-12-01

We examine the source mechanisms of earthquakes occurring in three California geothermal fields: The Geysers, Salton Sea, and Coso. We find source mechanisms ranging from strike slip faulting, consistent with the tectonic settings, to dip slip with unusually steep dip angles which are inconsistent with local structures. For example, we identify a fault zone in the Salton Sea Geothermal Field imaged using precisely-relocated hypocenters with a dip angle of 60° yet double-couple focal mechanisms indicate higher-angle dip-slip on ≥75° dipping planes. We observe considerable temporal variability in the distribution of source mechanisms. For example, at the Salton Sea we find that the number of high angle dip-slip events increased after 1989, when net-extraction rates were highest. There is a concurrent decline in strike-slip and strike-slip-normal faulting, the mechanisms expected from regional tectonics. These unusual focal mechanisms and their spatio-temporal patterns are enigmatic in terms of our understanding of faulting in geothermal regions. While near-vertical fault planes are expected to slip in a strike-slip sense, and dip slip is expected to occur on moderately dipping faults, we observe dip slip on near-vertical fault planes. However, for plausible stress states and accounting for geothermal production, the resolved fault planes should be stable. We systematically analyze the source mechanisms of these earthquakes using full moment tensor inversion to understand the constraints imposed by assuming a double-couple source. Applied to The Geysers field, we find a significant reduction in the number of high-angle dip-slip mechanisms using the full moment tensor. The remaining mechanisms displaying high-angle dip-slip could be consistent with faults accommodating subsidence and compaction associated with volumetric strain changes in the geothermal reservoir.

Microwave radiometric studies and ground truth measurements of the NASA/USGS Southern California test site

NASA Technical Reports Server (NTRS)

Edgerton, A. T.; Trexler, D. T.; Sakamoto, S.; Jenkins, J. E.

1969-01-01

The field measurement program conducted at the NASA/USGS Southern California Test Site is discussed. Ground truth data and multifrequency microwave brightness data were acquired by a mobile field laboratory operating in conjunction with airborne instruments. The ground based investigations were performed at a number of locales representing a variety of terrains including open desert, cultivated fields, barren fields, portions of the San Andreas Fault Zone, and the Salton Sea. The measurements acquired ground truth data and microwave brightness data at wavelengths of 0.8 cm, 2.2 cm, and 21 cm.

Pesticide concentrations in water and in suspended and bottom sediments in the New and Alamo rivers, Salton Sea Watershed, California, April 2003

USGS Publications Warehouse

LeBlanc, Lawrence A.; Orlando, James L.; Kuivila, Kathryn

2004-01-01

This report contains pesticide concentration data for water, and suspended and bed sediment samples collected in April 2003 from twelve sites along the New and Alamo Rivers in the Salton Sea watershed, in southeastern California. The study was done in collaboration with the California State Regional Water Quality Control Board, Colorado River Region, to assess inputs of current-use pesticides associated with water and sediment into the New and Alamo Rivers. Five sites along the New River and seven sites along the Alamo River, downstream of major agricultural drains, were selected and covered the lengths of the rivers from the international boundary to approximately 1.5 km from the river mouths. Sampling from bridges occurred at seven of the twelve sites. At these sites, streamflow measurements were taken. These same sites were also characterized for cross-stream homogeneity by measuring dissolved oxygen, pH, specific conductance, temperature, and suspended solids concentration at several vertical (depths) and horizontal (cross-stream) points across the river. Large volume water samples (200?300 L) were collected for isolation of suspended sediments by flow-through centrifugation. Water from the outflow of the flow-through centrifuge was sampled for the determination of aqueous pesticide concentrations. In addition, bottom sediments were sampled at each site. Current-use pesticides and legacy organochlorine compounds (p,p'-DDT, p,p'-DDE and p,p'-DDD) were extracted from sediments and measured via gas chromatography/mass spectrometry (GC/MS). Organic carbon and percentage of fines were also determined for suspended and bottom sediments. Cross-stream transects of dissolved constituents and suspended sediments showed that the rivers were fairly homogeneous at the sites sampled. Streamflow was higher at the outlet sites, with the Alamo River having higher flow (1,240 cfs) than the New River (798 cfs). Twelve current-use pesticides, one legacy organochlorine compound (p

Earth observations taken by the Expedition Seven crew

NASA Image and Video Library

2003-10-09

ISS007-E-16876 (9 October 2003) --- This view featuring the Salton Sea was taken by an Expedition 7 crewmember onboard the International Space Station (ISS). This wide image shows a portion of drought-stricken southern California, including the urban sprawl of San Bernardino and Riverside, the agricultural development of the Imperial Valley and the Salton Sea sporting a huge swirl, speculated to be an algal bloom. The coastal region is obscured by fog.

Irregular focal mechanisms observed at Salton Sea Geothermal Field: Possible influences of anthropogenic stress perturbations

USGS Publications Warehouse

Crandall-Bear, Aren; Barbour, Andrew J.; Schoenball, Martin; Schoenball, Martin

2018-01-01

At the Salton Sea Geothermal Field (SSGF), strain accumulation is released through seismic slip and aseismic deformation. Earthquake activity at the SSGF often occurs in swarm-like clusters, some with clear migration patterns. We have identified an earthquake sequence composed entirely of focal mechanisms representing an ambiguous style of faulting, where strikes are similar but deformation occurs due to steeply-dipping normal faults with varied stress states. In order to more accurately determine the style of faulting for these events, we revisit the original waveforms and refine estimates of P and S wave arrival times and displacement amplitudes. We calculate the acceptable focal plane solutions using P-wave polarities and S/P amplitude ratios, and determine the preferred fault plane. Without constraints on local variations in stress, found by inverting the full earthquake catalog, it is difficult to explain the occurrence of such events using standard fault-mechanics and friction. Comparing these variations with the expected poroelastic effects from local production and injection of geothermal fluids suggests that anthropogenic activity could affect the style of faulting.

Feedbacks Among Rifting, Erosion, Lithospheric Rupture, and Crustal Recycling: From the Colorado River to the Salton Trough and Gulf of California (Invited)

NASA Astrophysics Data System (ADS)

Dorsey, R. J.; Lazear, G. D.

2013-12-01

Many studies examine the influence of climate and erosion on growth of convergent orogens, but feedbacks between tectonics and erosion in extensional and transtensional settings are less well understood. The Colorado River has delivered a huge volume of sediment to rapidly subsiding transtensional basins along the Pacific - North America plate boundary over the past ~5.5 million years. Oblique rifting, rupture, and rapid subsidence drive a newly recognized style of crustal recycling in which sediment is funneled out of the continental interior by a large river and delivered to subsiding basins where it is rapidly converted to a new generation of crust at a rifted continental margin. Transfer of crust can be tracked because the eroding source (Colorado Plateau) and depositional sinks (Salton Trough and northern Gulf of California) are intact and well preserved. Using distribution of late Miocene basalt flows and thermochronologic data, we calculate that 3.4 × 1.2 x 105 km3 of rock has been eroded from the Colorado Plateau since 10 Ma. Most of this erosion occurred starting 5.5-6.0 Ma when the river drainage became integrated and incision rates increased dramatically. Two estimates for the volume of Colorado River sediment stored in basinal sinks since ~5.5 Ma are: (1) 2.8 × 0.6 x 105 km3 assuming that crust between 5 and 10-12 km depth in the plate-boundary basins is young metasedimentary rock mixed with intrusions; or (2) 1.55 × 0.35 x 105 km3 assuming that crust below 4-5 km is thinned pre-Cenozoic crystalline rock. Significant overlap of estimate 1 with the volume eroded from the Plateau provides new support for a model of lithospheric rupture and crustal recycling in the Salton Trough and northern Gulf of California. Assuming an average density of 2.3-2.5 g/cc and the preferred volume estimate above, the total mass of crust transferred is roughly 5.1-11.5 x 1014 metric tons, representing an average annual flux of 156 × 60 Mt/yr since 5.3 Ma (when the

Earth Observation taken during the STS-41G mission

NASA Image and Video Library

2009-06-25

41G-121-057 (5-13 Oct 1984) --- South-looking view of southern California and Baja California. Los Angeles area at lower right. Part of the Imperial Valley, Salton Sea at lower center. Baja is at upper left.

Structure of the active rift zone and margins of the northern Imperial Valley from Salton Seismic Imaging Project (SSIP) data

NASA Astrophysics Data System (ADS)

Livers, A.; Han, L.; Delph, J. R.; White-Gaynor, A. L.; Petit, R.; Hole, J. A.; Stock, J. M.; Fuis, G. S.

2012-12-01

First-arrival refraction data were used to create a seismic velocity model of the upper crust across the actively rifting northern Imperial Valley and its margins. The densely sampled seismic refraction data were acquired by the Salton Seismic Imaging Project (SSIP) , which is investigating rift processes in the northern-most rift segment of the Gulf of California extensional province and earthquake hazards at the southern end of the San Andreas Fault system. A 95-km long seismic line was acquired across the northern Imperial Valley, through the Salton Sea geothermal field, parallel to the five Salton Butte volcanoes and perpendicular to the Brawley Seismic Zone and major strike-slip faults. Nineteen explosive shots were recorded with 100 m seismometer spacing across the valley and with 300-500 m spacing into the adjacent ranges. First-arrival travel times were picked from shot gathers along this line and a seismic velocity model was produced using tomographic inversion. Sedimentary basement and seismic basement in the valley are interpreted to be sediment metamorphosed by the very high heat flow. The velocity model shows that this basement to the west of the Brawley Seismic Zone is at ~4-km depth. The basement shallows to ~2-km depth in the active geothermal field and Salton Buttes volcanic field which locally coincide with the Brawley Seismic Zone. At the eastern edge of the geothermal field, the basement drops off again to ~3.5-km depth. The eastern edge of the valley appears to be fault bounded by the along-strike extension of the Sand Hills Fault, an inactive strike-slip fault. The seismic velocities to the east of the fault correspond to metamorphic rock of the Chocolate Mountains, different from the metamorphosed basement in the valley. The western edge of the valley appears to be fault bounded by the active Superstition Hills Fault. To the west of the valley, >4-km deep valley basement extends to the active Superstition Hills Fault. Basement then shallows

Sea otters are recolonizing southern California in fits and starts

USGS Publications Warehouse

Lafferty, Kevin D.; Tinker, M. Tim

2014-01-01

After near extinction as a result of the fur trade in the 1700s and 1800s, the southern sea otter slowly reoccupied the core of its range in central California. Range expansion beyond central California is seen as key to full recovery of otters, but the rate of expansion has been sporadic, raising concerns about habitat quality in southern California. To describe the range expansion of sea otters from central into southern California, we used skiff surveys, aerial surveys, and archival time-depth recorders from 2004 to 2013. These observations show that range expansion began when male otters swam southeast of Point Conception (Cojo Anchorage), perhaps to seek refuge from bad weather and to feed on unexploited resources. After several years of seasonal use by male groups, females began to use the area, leading to reproduction and a secondary increase in abundance. In contrast, a second male group that moved farther down the coast to Coal Oil Point stalled and retreated. Such range expansion and contraction can be explained by the social nature of sea otters, which acts to slow dispersal away from groups. Otter densities at Cojo Anchorage are now approaching equilibrium levels reported for central California. As in central California, otters rested in and near kelp forest habitat, but used deeper water for foraging. Together, these observations suggest habitat in the Santa Barbara Channel can still support sea otters, but range expansion of otters into southern California will be episodic due to social dynamics.

Seismic calibration shots conducted in 2009 in the Imperial Valley, southern California, for the Salton Seismic Imaging Project (SSIP)

USGS Publications Warehouse

Murphy, Janice; Goldman, Mark; Fuis, Gary; Rymer, Michael; Sickler, Robert; Miller, Summer; Butcher, Lesley; Ricketts, Jason; Criley, Coyn; Stock, Joann; Hole, John; Chavez, Greg

2011-01-01

Rupture of the southern section of the San Andreas Fault, from the Coachella Valley to the Mojave Desert, is believed to be the greatest natural hazard facing California in the near future. With an estimated magnitude between 7.2 and 8.1, such an event would result in violent shaking, loss of life, and disruption of lifelines (freeways, aqueducts, power, petroleum, and communication lines) that would bring much of southern California to a standstill. As part of the Nation's efforts to prevent a catastrophe of this magnitude, a number of projects are underway to increase our knowledge of Earth processes in the area and to mitigate the effects of such an event. One such project is the Salton Seismic Imaging Project (SSIP), which is a collaborative venture between the United States Geological Survey (USGS), California Institute of Technology (Caltech), and Virginia Polytechnic Institute and State University (Virginia Tech). This project will generate and record seismic waves that travel through the crust and upper mantle of the Salton Trough. With these data, we will construct seismic images of the subsurface, both reflection and tomographic images. These images will contribute to the earthquake-hazard assessment in southern California by helping to constrain fault locations, sedimentary basin thickness and geometry, and sedimentary seismic velocity distributions. Data acquisition is currently scheduled for winter and spring of 2011. The design and goals of SSIP resemble those of the Los Angeles Region Seismic Experiment (LARSE) of the 1990's. LARSE focused on examining the San Andreas Fault system and associated thrust-fault systems of the Transverse Ranges. LARSE was successful in constraining the geometry of the San Andreas Fault at depth and in relating this geometry to mid-crustal, flower-structure-like decollements in the Transverse Ranges that splay upward into the network of hazardous thrust faults that caused the 1971 M 6.7 San Fernando and 1987 M 5

Structure of the San Andreas Fault Zone in the Salton Trough Region of Southern California: A Comparison with San Andreas Fault Structure in the Loma Prieta Area of Central California

NASA Astrophysics Data System (ADS)

Fuis, G. S.; Catchings, R.; Scheirer, D. S.; Goldman, M.; Zhang, E.; Bauer, K.

2016-12-01

The San Andreas fault (SAF) in the northern Salton Trough, or Coachella Valley, in southern California, appears non-vertical and non-planar. In cross section, it consists of a steeply dipping segment (75 deg dip NE) from the surface to 6- to 9-km depth, and a moderately dipping segment below 6- to 9-km depth (50-55 deg dip NE). It also appears to branch upward into a flower-like structure beginning below about 10-km depth. Images of the SAF zone in the Coachella Valley have been obtained from analysis of steep reflections, earthquakes, modeling of potential-field data, and P-wave tomography. Review of seismological and geodetic research on the 1989 M 6.9 Loma Prieta earthquake, in central California (e.g., U.S. Geological Survey Professional Paper 1550), shows several features of SAF zone structure similar to those seen in the northern Salton Trough. Aftershocks in the Loma Prieta epicentral area form two chief clusters, a tabular zone extending from 18- to 9-km depth and a complex cluster above 5-km depth. The deeper cluster has been interpreted to surround the chief rupture plane, which dips 65-70 deg SW. When double-difference earthquake locations are plotted, the shallower cluster contains tabular subclusters that appear to connect the main rupture with the surface traces of the Sargent and Berrocal faults. In addition, a diffuse cluster may surround a steep to vertical fault connecting the main rupture to the surface trace of the SAF. These interpreted fault connections from the main rupture to surface fault traces appear to define a flower-like structure, not unlike that seen above the moderately dipping segment of the SAF in the Coachella Valley. But importantly, the SAF, interpreted here to include the main rupture plane, appears segmented, as in the Coachella Valley, with a moderately dipping segment below 9-km depth and a steep to vertical segment above that depth. We hope to clarify fault-zone structure in the Loma Prieta area by reanalyzing active

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

NASA Astrophysics Data System (ADS)

Stock, J. M.

2016-12-01

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

Instability model for recurring large and great earthquakes in southern California

USGS Publications Warehouse

Stuart, W.D.

1985-01-01

The locked section of the San Andreas fault in southern California has experienced a number of large and great earthquakes in the past, and thus is expected to have more in the future. To estimate the location, time, and slip of the next few earthquakes, an earthquake instability model is formulated. The model is similar to one recently developed for moderate earthquakes on the San Andreas fault near Parkfield, California. In both models, unstable faulting (the earthquake analog) is caused by failure of all or part of a patch of brittle, strain-softening fault zone. In the present model the patch extends downward from the ground surface to about 12 km depth, and extends 500 km along strike from Parkfield to the Salton Sea. The variation of patch strength along strike is adjusted by trial until the computed sequence of instabilities matches the sequence of large and great earthquakes since a.d. 1080 reported by Sieh and others. The last earthquake was the M=8.3 Ft. Tejon event in 1857. The resulting strength variation has five contiguous sections of alternately low and high strength. From north to south, the approximate locations of the sections are: (1) Parkfield to Bitterwater Valley, (2) Bitterwater Valley to Lake Hughes, (3) Lake Hughes to San Bernardino, (4) San Bernardino to Palm Springs, and (5) Palm Springs to the Salton Sea. Sections 1, 3, and 5 have strengths between 53 and 88 bars; sections 2 and 4 have strengths between 164 and 193 bars. Patch section ends and unstable rupture ends usually coincide, although one or more adjacent patch sections may fail unstably at once. The model predicts that the next sections of the fault to slip unstably will be 1, 3, and 5; the order and dates depend on the assumed length of an earthquake rupture in about 1700. ?? 1985 Birkha??user Verlag.

Phylogenomic characterization of California sea lion adenovirus-1.

PubMed

Cortés-Hinojosa, Galaxia; Gulland, Frances M D; Goldstein, Tracey; Venn-Watson, Stephanie; Rivera, Rebecca; Waltzek, Thomas B; Salemi, Marco; Wellehan, James F X

2015-04-01

Significant adenoviral diversity has been found in humans, but in domestic and wild animals the number of identified viruses is lower. Here we present the complete genome of a recently discovered mastadenovirus, California sea lion adenovirus 1 (CSLAdV-1) isolated from California sea lions (Zalophus californianus), an important pathogen associated with hepatitis in pinnipeds. The genome of this virus has the typical mastadenoviral structure with some notable differences at the carboxy-terminal end, including a dUTPase that does not cluster with other mastadenoviral dUTPases, and a fiber that shows similarity to a trans-sialidase of Trypanosoma cruzi and choline-binding protein A (CbpA) of Streptococcus pneumoniae. The GC content is low (36%), and phylogenetic analyses placed the virus near the root of the clade infecting laurasiatherian hosts in the genus Mastadenovirus. These findings support the hypothesis that CSLAdV-1 in California sea lions represents a host jump from an unknown mammalian host in which it is endemic. Copyright © 2015 Elsevier B.V. All rights reserved.

Episodic Holocene eruption of the Salton Buttes rhyolites, California, from paleomagnetic, U-Th, and Ar/Ar dating

USGS Publications Warehouse

Wright, Heather M.; Vazquez, Jorge A.; Champion, Duane E.; Calvert, Andrew T.; Mangan, Margaret T.; Stelten, Mark E.; Cooper, Kari M.; Herzig, Charles; Schriener Jr., Alexander

2015-01-01

In the Salton Trough, CA, five rhyolite domes form the Salton Buttes: Mullet Island, Obsidian Butte, Rock Hill, North and South Red Hill, from oldest to youngest. Results presented here include 40Ar/39Ar anorthoclase ages, 238U-230Th zircon crystallization ages, and comparison of remanent paleomagnetic directions with the secular variation curve, which indicate that all domes are Holocene. 238U-230Th zircon crystallization ages are more precise than but within uncertainty of 40Ar/39Ar anorthoclase ages, suggesting that zircon crystallization proceeded until shortly before eruption in all cases except one. Remanent paleomagnetic directions require three eruption periods: (1) Mullet Island, (2) Obsidian Butte, and (3) Rock Hill, North Red Hill, and South Red Hill. Borehole cuttings logs document up to two shallow tephra layers. North and South Red Hills likely erupted within 100 years of each other, with a combined 238U-230Th zircon isochron age of: 2.83 ± 0.60 ka (2 sigma); paleomagnetic evidence suggests this age predates eruption by hundreds of years (1800 cal BP). Rock Hill erupted closely in time to these eruptions. The Obsidian Butte 238U-230Th isochron age (2.86 ± 0.96 ka) is nearly identical to the combined Red Hill age, but its Virtual Geomagnetic Pole position suggests a slightly older age. The age of aphyric Mullet Island dome is the least well constrained: zircon crystals are resorbed and the paleomagnetic direction is most distinct; possible Mullet Island ages include ca. 2300, 5900, 6900, and 7700 cal BP. Our results constrain the duration of Salton Buttes volcanism to between ca. 5900 and 500 years.

Fault tectonics and earthquake hazards in parts of southern California. [penninsular ranges, Garlock fault, Salton Trough area, and western Mojave Desert

NASA Technical Reports Server (NTRS)

Merifield, P. M. (Principal Investigator); Lamar, D. L.; Gazley, C., Jr.; Lamar, J. V.; Stratton, R. H.

1976-01-01

The author has identified the following significant results. Four previously unknown faults were discovered in basement terrane of the Peninsular Ranges. These have been named the San Ysidro Creek fault, Thing Valley fault, Canyon City fault, and Warren Canyon fault. In addition fault gouge and breccia were recognized along the San Diego River fault. Study of features on Skylab imagery and review of geologic and seismic data suggest that the risk of a damaging earthquake is greater along the northwestern portion of the Elsinore fault than along the southeastern portion. Physiographic indicators of active faulting along the Garlock fault identifiable in Skylab imagery include scarps, linear ridges, shutter ridges, faceted ridges, linear valleys, undrained depressions and offset drainage. The following previously unrecognized fault segments are postulated for the Salton Trough Area: (1) An extension of a previously known fault in the San Andreas fault set located southeast of the Salton Sea; (2) An extension of the active San Jacinto fault zone along a tonal change in cultivated fields across Mexicali Valley ( the tonal change may represent different soil conditions along opposite sides of a fault). For the Skylab and LANDSAT images studied, pseudocolor transformations offer no advantages over the original images in the recognition of faults in Skylab and LANDSAT images. Alluvial deposits of different ages, a marble unit and iron oxide gossans of the Mojave Mining District are more readily differentiated on images prepared from ratios of individual bands of the S-192 multispectral scanner data. The San Andreas fault was also made more distinct in the 8/2 and 9/2 band ratios by enhancement of vegetation differences on opposite sides of the fault. Preliminary analysis indicates a significant earth resources potential for the discrimination of soil and rock types, including mineral alteration zones. This application should be actively pursued.

Chronology of Miocene-Pliocene deposits at Split Mountain Gorge, Southern California: A record of regional tectonics and Colorado River evolution

USGS Publications Warehouse

Dorsey, R.J.; Fluette, A.; McDougall, K.; Housen, B.A.; Janecke, S.U.; Axen, G.J.; Shirvell, C.R.

2007-01-01

Late Miocene to early Pliocene deposit at Split Mountain Gorge, California, preserve a record of basinal response to changes in regional tectonics, paleogeography, and evolution of the Colorado River. The base of the Elephant Trees Formation, magnetostratigraphically dated as 8.1 ?? 0.4 Ma, provides the earliest well-dated record of extension in the southwestern Salton Trough. The oldest marine sediments are ca. 6.3 Ma. The nearly synchronous timing of marine incursion in the Salton Trough and northern Gulf of California region supports a model for localization of Pacific-North America plate motion in the Gulf ca. 6 Ma. The first appearance of Colorado River sand at the Miocene-Pliocene boundary (5.33 Ma) suggests rapid propagation of the river to the Salton Trough, and supports a lake-spillover hypothesis for initiation of the lower Colorado River. ?? 2007 Geological Society of America.

Future loss of Arctic sea-ice cover could drive a substantial decrease in California's rainfall.

PubMed

Cvijanovic, Ivana; Santer, Benjamin D; Bonfils, Céline; Lucas, Donald D; Chiang, John C H; Zimmerman, Susan

2017-12-05

From 2012 to 2016, California experienced one of the worst droughts since the start of observational records. As in previous dry periods, precipitation-inducing winter storms were steered away from California by a persistent atmospheric ridging system in the North Pacific. Here we identify a new link between Arctic sea-ice loss and the North Pacific geopotential ridge development. In a two-step teleconnection, sea-ice changes lead to reorganization of tropical convection that in turn triggers an anticyclonic response over the North Pacific, resulting in significant drying over California. These findings suggest that the ability of climate models to accurately estimate future precipitation changes over California is also linked to the fidelity with which future sea-ice changes are simulated. We conclude that sea-ice loss of the magnitude expected in the next decades could substantially impact California's precipitation, thus highlighting another mechanism by which human-caused climate change could exacerbate future California droughts.

Science, policy, and management of irrigation-induced selenium contamination in california.

PubMed

Kausch, Matteo F; Pallud, Céline E

2013-11-01

Selenium was recognized as an important aquatic contaminant following the identification of widespread deformities in waterfowl at the agricultural drainage evaporation ponds of the Kesterson Reservoir (California) in 1983. Since then, California has been the focal point for global research and management of Se contamination. We analyzed the history and current developments in science, policy, and management of irrigation-induced Se contamination in California. In terms of management, we evaluated the effects of improvements in the design of local attenuation methods (drainage reuse and evaporation ponds) in conjunction with the development of programs for Se load reductions at the regional scale (namely the Grassland Bypass Project). In terms of policy, the USEPA is currently working on site-specific water quality criteria for the San Francisco Bay Delta that may be a landmark for future legislation on Se in natural water bodies. We provide a critical analysis of this approach and discuss challenges and opportunities in expanding it to other locations such as the Salton Sea. Management lessons learned in California and the novel policy approach may help prevent future events of Se contamination. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Constraints on mantle melt geometries from body wave attenuation in the Salton Trough and Snake River Plain

NASA Astrophysics Data System (ADS)

Byrnes, J. S.; Bezada, M.

2017-12-01

Melt can be retained in the mantle at triple junctions between grain boundaries, be spread in thin films along two-grain boundaries, or be organized by shear into elongate melt-rich bands. Which of these geometries is most prevalent is unknown. This ambiguity makes the interpretation of anomalous seismic velocities and quality factors difficult, since different geometries would result in different mechanical effects. Here, we compare observations of seismic attenuation beneath the Salton Trough and the Snake River Plain; two regions where the presence of melt has been inferred. The results suggest that seismic attenuation is diagnostic of melt geometry. We measure the relative attenuation of P waves from deep focus earthquakes using a time-domain method. Even though the two regions are underlain by comparably strong low-velocity anomalies, their attenuation signature is very different. The upper mantle beneath the Salton Trough is sufficiently attenuating that the presence of melt must lower Qp, while attenuation beneath the Snake River Plain is not anomalous with respect to surrounding regions. These seemingly contradictory results can be reconciled if different melt geometries characterize each region. SKS splitting from the Salton Trough suggests that melt is organized into melt-rich bands, while this is not the case for the Snake River Plain. We infer that beneath the Snake River Plain melt is retained at triple junctions between grain boundaries, a geometry that is not predicted to cause seismic attenuation. More elongate geometries beneath the Salton Trough may cause seismic attenuation via the melt-squirt mechanism. In light of these results, we conclude that prior observations of low seismic velocities with somewhat high quality factors beneath the East Pacific Rise and Southern California suggest that melt does not organize into elongate bands across much of the asthenosphere.

A consortium of three brings real geothermal power for California's Imperial valley -- at last

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wehlage, E.F.

1983-04-01

Imperial Valley's geothermal history gets a whole new chapter with dedication ceremony for southern California's unusual 10,000 kilowatt power station-SCE in joint corporate venture with Southern Pacific and Union Oil. America's newest and unique electric power generation facility, The Salton Sea Geothermal-Electric Project, was the the site of a formal dedication ceremony while the sleek and stainless jacketed piping and machinery were displayed against a flawlessly brilliant January sky - blue and flecked with a few whisps of high white clouds, while plumes of geothermal steam rose across the desert. The occasion was the January 19, 1983, ceremonial dedication ofmore » the unique U.S.A. power generation facility constructed by an energy consortium under private enterprise, to make and deliver electricity, using geothermal steam released (with special cleaning and treatment) from magma-heated fluids produced at depths of 3,000 to 6,000 feet beneath the floor of the Imperial Valley near Niland and Brawley, California.« less

Transformation of the genital epithelial tract occurs early in California sea lion development

PubMed Central

Barragán-Vargas, Cecilia; Montano-Frías, Jorge; Ávila Rosales, Germán; Godínez-Reyes, Carlos R.; Acevedo-Whitehouse, Karina

2016-01-01

An unusually high prevalence of metastatic urogenital carcinoma has been observed in free-ranging California sea lions stranded off the coast of California in the past two decades. No cases have been reported for sea lions in the relatively unpolluted Gulf of California. We investigated occurrence of genital epithelial transformation in 60 sea lions (n=57 pups and 3 adult females) from the Gulf of California and examined whether infection by a viral pathogen previously found to be associated with urogenital carcinoma accounted for such alterations. We also explored the contribution of MHC class II gene expression on transformation. Cellular alterations, such as squamous cell atypia (ASC), atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesions were observed in 42% of the pups and in 67% of the adult females. Normal genital epithelium was more common in male than female pups. ASC was five times more likely to occur in older pups. Epithelial alterations were unrelated to infection by the potentially oncogenic otarine type I gammaherpesvirus (OtHV-1), but ASCUS was more common in pups with marked and severe inflammation. Expression of MHC class II DRB loci (Zaca DRB-D) by peripheral antigen-presenting leucocytes showed a slightly ‘protective’ effect for ASC. We propose that transformation of the California sea lion genital epithelium is relatively common in young animals, increases with age and is probably the result of infection by an unidentified pathogen. Expression of a specific MHC class II gene, suggestive of presentation of specific antigenic peptides to immune effectors, appears to lower the risk of transformation. Our study provides the first evidence that epithelial transformation of the California sea lion genital tract is relatively common, even from an early age, and raises questions regarding differences in sea lion cancer-detection and -repair success between geographical regions. PMID:27069641

Earth Observation taken by the STS-125 Crew

NASA Image and Video Library

2009-05-13

S125-E-007103 (13 May 2009) --- Part of Mexico's Baja California and part of southern California, including the Los Angeles and San Diego areas, can be seen in this STS-125 still photo taken from the Space Shuttle Atlantis as it passed near the Pacific Coast. The Gulf of California is in the foreground. The Salton Sea/Imperial Valley area can be seen at top center.

Sea-floor gouges caused by migrating gray whales off northern California

USGS Publications Warehouse

Cacchione, D.A.; Drake, D.E.; Field, M.E.; Tate, G.B.

1987-01-01

Side-scan sonar records collected during March and April 1981 and 1982 off northern California contain elongate depressions whose sizes and shapes are similar to sea-floor gouges made by feeding gray whales (Eschrichtius robustus) in the northern Bering Sea and in shallow embayments off British Columbia. The discovery of the whale gouges in the sonar records was unexpected, and supports some of the previous speculation that gray whales feed opportunistically during migration. Gouges occupy about 0.032% of the 7.6 km2 of sea floor that was surveyed, which represents about 575 metric tons of excavated material. Although seemingly minor in amount, the total amount of bottom sediment removed from the central and northern California continental shelf by gray whale activities year after year represents macroscale biologically induced erosion and could have significant geological implications in shelf erosion and depositional schemes. This is the only published evidence of benthic feeding by gray whales along their migration route off northern California. ?? 1987.

Controlling tailwater sediment and phosphorus concentrations with polyacrylamide in the Imperial Valley, California.

PubMed

Goodson, Christopher C; Schwartz, Gregory; Amrhein, Christopher

2006-01-01

External loading of phosphorus (P) from agricultural surface discharge (tailwater) is the main cause of excessive algae growth and the eutrophication of the Salton Sea, California. Continuous polyacrylamide (PAM) applications to agricultural irrigation water inflows were evaluated as a means of reducing sediment and P in tailwater. Zero (control) and 1 mg L(-1) PAM (PAM1) treatments were compared at 17 Imperial Valley field sites. Five and 10 mg L(-1) PAM treatments (PAM5, PAM10) were conducted at one site. The particulate phosphorus (Pp) fraction was determined as the difference between total phosphorus (Pt) and the soluble phosphorus (Ps) fraction. We observed 73, 82, and 98% turbidity reduction with PAM1, PAM5, and PAM10 treatments. Although eight field sites had control tailwater sediment concentrations above the New River total maximum daily loads (TMDL), all but one were made compliant during their paired PAM1 treatments. While PAM1 and PAM10 reduced tail water Pp by 31 and 78%, none of the treatments tested reduced Ps. This may have been caused by high irrigation water Na concentrations which would reduce Ca adsorption and Ca-phosphate bridging on the PAM. The PAM1 treatments resulted in <0.5 mg L(-1) drain water polyacrylamide concentrations 1.6 km downstream of PAM addition, while PAM5 and PAM10 treatments produced > 2 mg L(-1) drain water polyacrylamide concentrations. We concluded that, although PAM practically eliminates Imperial Valley tailwater sediment loads, it does not effectively reduce tailwater Ps, the P fraction most responsible for the eutrophication of the Salton Sea.

Strike-slip Fault Structure in the Salton Trough and Deformation During and After the 2010 M7.2 El Mayor-Cucapah Earthquake from Geodetic and Seismic Data

NASA Astrophysics Data System (ADS)

Fielding, E. J.; Sun, J.; Gonzalez-Ortega, A.; González-Escobar, M.; Freed, A. M.; Burgmann, R.; Samsonov, S. V.; Gonzalez-Garcia, J.; Fletcher, J. M.; Hinojosa, A.

2013-12-01

The Pacific-North America plate boundary character changes southward from the strike-slip and transpressional configuration along most of California to oblique rifting in the Gulf of California, with a transitional zone of transtension beneath the Salton Trough in southernmost California and northern Mexico. The Salton Trough is characterized by extremely high heat flow and thin lithosphere with a thick fill of sedimentary material delivered by the Colorado River during the past 5-6 million years. Because of the rapid sedimentation, most of the faults in Salton Trough are buried and reveal themselves when they slip either seismically or aseismically. They can also be located by refraction and reflection of seismic waves. The 4 April 2010 El Mayor-Cucapah earthquake (Mw 7.2) in Baja California and Sonora, Mexico is probably the largest earthquake in the Salton Trough for at least 120 years, and had primarily right-lateral strike-slip motion. The earthquake ruptured a complex set of faults that lie to the west of the main plate boundary fault, the Cerro Prieto Fault, and shows that the strike-slip fault system in the southern Salton Trough has multiple sub-parallel active faults, similar to southern California. The Cerro Prieto Fault is still likely absorbing the majority of strain in the plate boundary. We study the coseismic and postseismic deformation of the 2010 earthquake with interferometric analysis of synthetic aperture radar (SAR) images (InSAR) and pixel tracking by subpixel correlation of SAR and optical images. We combine sampled InSAR and subpixel correlation results with GPS (Global Positioning System) offsets at PBO (Plate Boundary Observatory) stations to estimate the likely subsurface geometry of the major faults that slipped during the earthquake and to derive a static coseismic slip model. We constrained the surface locations of the fault segments to mapped locations in the Sierra Cucapah to the northwest of the epicenter. SAR along-track offsets

Investigation of ecosystems impacts from geothermal development in Imperial Valley, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shinn, J.H.; Ireland, R.R.; Kercher, J.R.

1979-07-13

A summary of three years of field ecological investigation in Imperial Valley Environmental Program is presented. The potential terrestrial habitat impacts of geothermal development are discussed for shorebirds and waterfowl habitat, the endangered clapper rail, powerline corridors, noise effects, animal trace element burdens, and the desert community. Aquatic habitats are discussed in terms of Salton Sea salinity, effects of geothermal brine discharges to the Salton Sea, trace element baselines, and potential toxicity of brine spills in freshwater. Studies of impacts on agriculture involved brine movement in soil, release of trace metals, trace element baselines in soil and plants, water requirementsmore » of crops, and H{sub 2}S effects on crop production in the presence of CO{sub 2} and ozone.« less

Advances in Mineral Dust Source Composition Measurement with Imaging Spectroscopy at the Salton Sea, CA

NASA Astrophysics Data System (ADS)

Green, R. O.; Realmuto, V. J.; Thompson, D. R.; Mahowald, N. M.; Pérez García-Pando, C.; Miller, R. L.; Clark, R. N.; Swayze, G. A.; Okin, G. S.

2015-12-01

Mineral dust emitted from the Earth's surface is a principal contributor to direct radiative forcing over the arid regions, where shifts in climate have a significant impact on agriculture, precipitation, and desert encroachment around the globe. Dust particles contribute to both positive and negative forcing, depending on the composition of the particles. Particle composition is a function of the surface mineralogy of dust source regions, but poor knowledge of surface mineralogy on regional to global scales limits the skill of Earth System models to predict shifts in regional climate around the globe. Earth System models include the source, emission, transport and deposition phases of the dust cycle. In addition to direct radiative forcing contributions, mineral dust impacts include indirect radiative forcing, modification of the albedo and melting rates of snow and ice, kinetics of tropospheric photochemistry, formation and deposition of acidic aerosols, supply of nutrients to aquatic and terrestrial ecosystems, and impact on human health and safety. We demonstrate the ability to map mineral dust source composition in the Salton Sea dust source region with imaging spectroscopy measurements acquired as part of the NASA HyspIRI preparatory airborne campaign. These new spectroscopically derived compositional measurements provide a six orders of magnitude improvement over current atlases for this dust source region and provide a pathfinder example for a remote measurement approach to address this critical dust composition gap for global Earth System models.

PATHOGENIC LEPTOSPIRA SEROVARS IN FREE-LIVING SEA LIONS IN THE GULF OF CALIFORNIA AND ALONG THE BAJA CALIFORNIA COAST OF MEXICO.

PubMed

Avalos-Téllez, Rosalía; Carrillo-Casas, Erika M; Atilano-López, Daniel; Godínez-Reyes, Carlos R; Díaz-Aparicio, Efrén; Ramírez-Delgado, David; Ramírez-Echenique, María F; Leyva-Leyva, Margarita; Suzán, Gerardo; Suárez-Güemes, Francisco

2016-04-28

The California sea lion ( Zalophus californianus ), a permanent inhabitant of the Gulf of California in Mexico, is susceptible to pathogenic Leptospira spp. infection, which can result in hepatic and renal damage and may lead to renal failure and death. During summer 2013, we used the microscopic agglutination test (MAT) to investigate the prevalence of anti-Leptospira antibodies in blood of clinically healthy sea lion pups from seven rookery islands on the Pacific Coast of Baja California (Pacific Ocean) and in the Gulf of California. We also used PCR to examine blood for Leptospira DNA. Isolation of Leptospira in liquid media was unsuccessful. We found higher antibody prevalence in sea lions from the rookery islands in the gulf than in those from the Pacific Coast. Antibodies against 11 serovars were identified in the Gulf of California population; the most frequent reactions were against serovars Bataviae (90%), Pyrogenes (86%), Wolffi (86%), Celledoni (71%), and Pomona (65%). In the Pacific Ocean population, MAT was positive against eight serovars, where Wolffi (88%), Pomona (75%), and Bataviae (70%) were the most frequent. Serum samples agglutinated with more than one Leptospira serovar. The maximum titer was 3,200. Each island had a different serology profile, and islands combined showed a distinct profile for each region. We detected pathogenic Leptospira DNA in 63% of blood samples, but we found no saprophytic Leptospira. Positive PCR results were obtained in blood samples with high and low MAT titers. Together, these two methods enhance the diagnosis and interpretation of sea lion leptospirosis. Our results may be related to human activities or the presence of other reservoirs with which sea lions interact, and they may also be related to sea lion stranding.

Views of the Sea Floor in Northern Monterey Bay, California

USGS Publications Warehouse

Storlazzi, Curt D.; Golden, Nadine E.; Finlayson, David P.

2008-01-01

A sonar survey that produced unprecedented high-resolution images of the sea floor in northern Monterey Bay was conducted in 2005 and 2006. The survey, performed over 14 days by the U.S. Geological Survey (USGS), consisted of 172 tracklines and over 300 million soundings and covered an area of 12.2 km2 (4.7 mi2). The goals of this survey were to collect high-resolution bathymetry (depth to the sea floor) and acoustic backscatter data (amount of sound energy bounced back from the sea floor, which provides information on sea-floor hardness and texture) from the inner continental shelf. These data will provide a baseline for future change analyses, geologic mapping, sediment- and contaminant-transport studies, benthic-habitat delineation, and numerical modeling efforts. The survey shows that the inner shelf in this area is extremely varied in nature, encompassing flat sandy areas, faults, boulder fields, and complex bedrock ridges that support rich marine ecosystems. Furthermore, many of these complex bedrock ridges form the ?reefs? that result in a number of California?s classic surf breaks.

California sea otter (Enhydra lutris nereis) census results, Spring 2017

USGS Publications Warehouse

Tinker, M. Tim; Hatfield, Brian B.

2017-09-29

The 2017 census of southern sea otters (Enhydra lutris nereis) was conducted between late April and early July along the mainland coast of central California and in April at San Nicolas Island in southern California. The 3-year average of combined counts from the mainland range and San Nicolas Island was 3,186, down by 86 sea otters from the previous year. This is the second year that the official index has exceeded 3,090, the Endangered Species Act delisting threshold identified in the U.S. Fish and Wildlife Service’s Southern Sea Otter Recovery Plan (the threshold would need to be exceeded for 3 consecutive years before delisting consideration). The 5-year average trend in abundance, including both the mainland range and San Nicolas Island populations, remains positive at 2.3 percent per year. Continuing lack of growth in the range peripheries likely explains the cessation of range expansion.

Cryptococcus albidus infection in a California sea lion (Zalophus californianus).

PubMed

Mcleland, Shannon; Duncan, Colleen; Spraker, Terry; Wheeler, Elizabeth; Lockhart, Shawn R; Gulland, Frances

2012-10-01

Sporadic cases of cryptococcosis have been reported in marine mammals, typically due to Cryptococcus neoformans and, more recently, to Cryptococcus gattii in cetaceans. Cryptococcus albidus, a ubiquitous fungal species not typically considered to be pathogenic, was recovered from a juvenile California sea lion (Zalophus californianus) rescued near San Francisco Bay, California. Yeast morphologically consistent with a Cryptococcus sp. was identified histologically in a lymph node and C. albidus was identified by an rDNA sequence from the lung. Infection with C. albidus was thought to have contributed to mortality in this sea lion, along with concurrent bacterial pneumonia. Cryptococcus albidus should be considered as a potential pathogen with a role in marine mammal morbidity and mortality.

Sea Grant in California: Twenty Years of Achievement.

ERIC Educational Resources Information Center

Amidei, Rosemary

Since 1968, the California Sea Grant program has operated to produce scientific research oriented to solving problems in marine resource development, management, and conservation. This document decribes the facets of this program, their accomplishments and goals. Discussions include: (1) historical notes; (2) coastal governance; (3) coastal…

Tissue heavy metal concentrations of stranded California sea lions (Zalophus californianus) in Southern California.

PubMed

Harper, Erin R; St Leger, Judy A; Westberg, Jody A; Mazzaro, Lisa; Schmitt, Todd; Reidarson, Tom H; Tucker, Melinda; Cross, Dee H; Puschner, Birgit

2007-06-01

Concentrations of nine heavy metals (As, Cd, Cu, Fe, Hg, Pb, Mn, Mo and Zn) were determined in the hepatic and renal tissues of 80 stranded California sea lions (Zalophus californianus). Significant age-dependant increases were observed in liver and kidney concentrations of cadmium and mercury, and renal zinc concentrations. Hepatic iron concentrations were significantly higher in females than males. Animals with suspected domoic acid associated pathological findings had significantly higher concentrations of liver and kidney cadmium; and significantly higher liver mercury concentrations when compared to animals classified with infectious disease or traumatic mortality. Significantly higher hepatic burdens of molybdenum and zinc were found in animals that died from infectious diseases. This is the largest study of tissue heavy metal concentrations in California sea lions to date. These data demonstrate how passive monitoring of stranded animals can provide insight into environmental impacts on marine mammals.

Detection and characterization of diverse coccidian protozoa shed by California sea lions.

PubMed

Girard, Yvette A; Johnson, Christine K; Fritz, Heather M; Shapiro, Karen; Packham, Andrea E; Melli, Ann C; Carlson-Bremer, Daphne; Gulland, Frances M; Rejmanek, Daniel; Conrad, Patricia A

2016-04-01

Tissue-cyst forming coccidia in the family Sarcocystidae are etiologic agents of protozoal encephalitis in marine mammals including the federally listed Southern sea otter (Enhydra lutris). California sea lions (Zalophus californianus), whose coastal habitat overlaps with sea otters, are definitive hosts for coccidian protozoa provisionally named Coccidia A, B and C. While Coccidia A and B have unknown clinical effects on aquatic wildlife hosts, Coccidia C is associated with severe protozoal disease in harbor seals (Phoca vitulina). In this study, we conducted surveillance for protozoal infection and fecal shedding in hospitalized and free-ranging California sea lions on the Pacific Coast and examined oocyst morphology and phenotypic characteristics of isolates via mouse bioassay and cell culture. Coccidia A and B were shed in similar frequency, particularly by yearlings. Oocysts shed by one free-ranging sea lion sampled at Año Nuevo State Park in California were previously unidentified in sea lions and were most similar to coccidia infecting Guadalupe fur seals (Arctocephalus townsendi) diagnosed with protozoal disease in Oregon (USA). Sporulated Coccidia A and B oocysts did not replicate in three strains of mice or in African green monkey kidney cells. However, cultivation experiments revealed that the inoculum of fecally-derived Coccidia A and B oocysts additionally contained organisms with genetic and antigenic similarity to Sarcocystis neurona; despite the absence of detectable free sporocysts in fecal samples by microscopic examination. In addition to the further characterization of Coccidia A and B in free-ranging and hospitalized sea lions, these results provide evidence of a new role for sea lions as putative mechanical vectors of S. neurona, or S. neurona-like species. Future work is needed to clarify the distribution, taxonomical status, and pathogenesis of these parasites in sea lions and other marine mammals that share their the near-shore marine

Detection and characterization of diverse coccidian protozoa shed by California sea lions

PubMed Central

Girard, Yvette A.; Johnson, Christine K.; Fritz, Heather M.; Shapiro, Karen; Packham, Andrea E.; Melli, Ann C.; Carlson-Bremer, Daphne; Gulland, Frances M.; Rejmanek, Daniel; Conrad, Patricia A.

2015-01-01

Tissue-cyst forming coccidia in the family Sarcocystidae are etiologic agents of protozoal encephalitis in marine mammals including the federally listed Southern sea otter (Enhydra lutris). California sea lions (Zalophus californianus), whose coastal habitat overlaps with sea otters, are definitive hosts for coccidian protozoa provisionally named Coccidia A, B and C. While Coccidia A and B have unknown clinical effects on aquatic wildlife hosts, Coccidia C is associated with severe protozoal disease in harbor seals (Phoca vitulina). In this study, we conducted surveillance for protozoal infection and fecal shedding in hospitalized and free-ranging California sea lions on the Pacific Coast and examined oocyst morphology and phenotypic characteristics of isolates via mouse bioassay and cell culture. Coccidia A and B were shed in similar frequency, particularly by yearlings. Oocysts shed by one free-ranging sea lion sampled at Año Nuevo State Park in California were previously unidentified in sea lions and were most similar to coccidia infecting Guadalupe fur seals (Arctocephalus townsendi) diagnosed with protozoal disease in Oregon (USA). Sporulated Coccidia A and B oocysts did not replicate in three strains of mice or in African green monkey kidney cells. However, cultivation experiments revealed that the inoculum of fecally-derived Coccidia A and B oocysts additionally contained organisms with genetic and antigenic similarity to Sarcocystis neurona; despite the absence of detectable free sporocysts in fecal samples by microscopic examination. In addition to the further characterization of Coccidia A and B in free-ranging and hospitalized sea lions, these results provide evidence of a new role for sea lions as putative mechanical vectors of S. neurona, or S. neurona-like species. Future work is needed to clarify the distribution, taxonomical status, and pathogenesis of these parasites in sea lions and other marine mammals that share their the near-shore marine

An Evaluation of Subsurface Plumbing of a Hydrothermal Seep Field and Possible Influence from Local Seismicity from New Time-Series Data Collected at the Davis-Schrimpf Seep Field, Salton Trough, California

NASA Astrophysics Data System (ADS)

Rao, A.; Onderdonk, N.

2016-12-01

The Davis­-Schrimpf Seep Field (DSSF) is a group of approximately 50 geothermal mud seeps (gryphons) in the Salton Trough of southeastern California. Its location puts it in line with the mapped San Andreas Fault, if extended further south, as well as within the poorly-understood Brawley Seismic Zone. Much of the geomorphology, geochemistry, and other characteristics of the DSSF have been analyzed, but its subsurface structure remains unknown. Here we present data and interpretations from five new temperature time­series from four separate gryphons at the DSSF, and compare them both amongst themselves, and within the context of all previously collected data to identify possible patterns constraining the subsurface dynamics. Simultaneously collected time-series from different seeps were cross-correlated to quantify similarity. All years' time-series were checked against the record of local seismicity to identify any seismic influence on temperature excursions. Time-series captured from the same feature in different years were statistically summarized and the results plotted to examine their evolution over time. We found that adjacent vents often alternate in temperature, suggesting a switching of flow path of the erupted mud at the scale of a few meters or less. Noticeable warming over time was observed in most of the features with time-series covering multiple years. No synchronicity was observed between DSSF features' temperature excursions, and seismic events within a 24 kilometer radius covering most of the width of the surrounding Salton Trough.

ASSOCIATION BETWEEN POSITIVE CANINE HEARTWORM (DIROFILARIA IMMITIS) ANTIGEN RESULTS AND PRESENCE OF ACANTHOCHEILONEMA ODENDHALI MICROFILARIA IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).

PubMed

Krucik, David D R; Van Bonn, William; Johnson, Shawn P

2016-03-01

This study establishes a relationship between positive canine heartworm (Dirofilaria immitis) test results frequently observed in California sea lions (Zalophus californianus) and infection with the filarid nematode Acanthocheilonema odendhali. Four commercially available canine heartworm antigen tests were evaluated for cross-reaction with A. odendhali in California sea lions. Sera were tested from fifteen California sea lions with A. odendhali-associated microfilaremia, confirmed by blood smear, and with no evidence of D. immitis infection at necropsy. Ninety-five percent of tests were falsely positive for D. immitis. This study also determined that the prevalence of A. odendhali infection in stranded California sea lions from central California is approximately 23% by comparing the number of findings of mircofilaremia to the total number of California sea lions sampled at The Marine Mammal Center between 2005 and 2011, inclusive. Acanthocheilonema odenhali microfilaremia in California sea lions is likely to cross-react with canine heartworm antigen tests, and clinicians should interpret results with caution.

Modeling Gas Dynamics in California Sea Lions

DTIC Science & Technology

2015-09-30

W. and Fahlman, A. (2009). Could beaked whales get the bends?. Effect of diving behaviour and physiology on modelled gas exchange for three species...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Modeling Gas Dynamics in California Sea Lions Andreas...to update a current gas dynamics model with recently acquired data for respiratory compliance (P-V), and body compartment size estimates in

Late Neogene marine incursions and the ancestral Gulf of California

USGS Publications Warehouse

McDougall, K.

2008-01-01

The late Neogene section in the Salton Trough, California, and along the lower Colorado River in Arizona is composed of marine units bracketed by nonmarine units. Microfossils from the marine deposits indicate that a marine incursion inundated the Salton Trough during the late Miocene. Water depths increased rapidly in the Miocene and eventually flooded the region now occupied by the Colorado River as far north as Parker, Arizona. Marine conditions were restricted in the Pliocene as the Colorado River filled the Salton Trough with sediments and the Gulf of California assumed its present configuration. Microfossils from the early part of this incursion include a diverse assemblage of benthic foraminifers (Amphistegina gibbosa, Uvigerina peregrina, Cassidulina delicata, and Bolivina interjuncta), planktic foraminifers (Globigerinoides obliquus, G. extremus, and Globigerina nepenthes), and calcareous nannoplankton (Discoaster brouweri, Discoaster aff. Discoaster surculus, Sphenolithus abies, and S. neoabies), whereas microfossils in the final phase contain a less diverse assemblage of benthic foraminifers that are diagnostic of marginal shallow-marine conditions (Ammonia, Elphidium, Bolivina, Cibicides, and Quinqueloculina). Evidence of an earlier middle Miocene marine incursion comes from reworked microfossils found near Split Mountain Gorge in the Fish Creek Gypsum (Sphenolithus moriformis) and near San Gorgonio Pass (Cyclicargolithus floridanus and Sphenolithus heteromorphus and planktic foraminifers). The middle Miocene incursion may also be represented by the older marine sedimentary rocks encountered in the subsurface near Yuma, Arizona, where rare middle Miocene planktic foraminifers are found. ?? 2008 The Geological Society of America.

Geothermal energy: opportunities for California commerce. Phase I report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1982-01-01

California's geographic and end-use markets which could directly use low and moderate temperature geothermal resources are ranked and described, as well as those which have the highest potential for near-term commercial development of these resources. Building on previous market surveys, the assessment determined that out of 38 geothermal resource areas with characteristics for direct use development, five areas have no perceived impediments to near-term development: Susanville, Litchfield, Ontario Hot Springs, Lake Elsinore, and the Salton Sea Geothermal Field. Twenty-nine applications were compared with previously selected criteria to determine their near-term potential for direct use of geothermal fluids. Seven categories weremore » found to have the least impediments to development; agriculture and district heating applications are considered the highest. Ten-year projections were conducted for fossil fuel displacement from the higher rated applications. It is concluded that greenhouses have the greatest displacement of 18 x 10/sup 6/ therms per year.« less

Faults on Skylab imagery of the Salton Trough area, Southern California

NASA Technical Reports Server (NTRS)

Merifield, P. M.; Lamar, D. L. (Principal Investigator)

1975-01-01

The author has identified the following significant results. Large segments of the major high angle faults in the Salton Trough area are readily identifiable in Skylab images. Along active faults, distinctive topographic features such as scarps and offset drainage, and vegetation differences due to ground water blockage in alluvium are visible. Other fault-controlled features along inactive as well as active faults visible in Skylab photography include straight mountain fronts, linear valleys, and lithologic differences producing contrasting tone, color or texture. A northwestern extension of a fault in the San Andreas set, is postulated by the regional alignment of possible fault-controlled features. The suspected fault is covered by Holocene deposits, principally windblown sand. A northwest trending tonal change in cultivated fields across Mexicali Valley is visible on Skylab photos. Surface evidence for faulting was not observed; however, the linear may be caused by differences in soil conditions along an extension of a segment of the San Jacinto fault zone. No evidence of faulting could be found along linears which appear as possible extensions of the Substation and Victory Pass faults, demonstrating that the interpretation of linears as faults in small scale photography must be corroborated by field investigations.

A Robotic Platform to Study the Foreflipper of the California Sea Lion.

PubMed

Kulkarni, Aditya A; Patel, Rahi K; Friedman, Chen; Leftwich, Megan C

2017-01-10

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most of their thrust with their large foreflippers. This protocol describes a robotic platform designed to study the hydrodynamic performance of the swimming California sea lion (Zalophus californianus). The robot is a model of the animal's foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the 'clap'). The kinematics of the sea lion's propulsive stroke are extracted from video data of unmarked, non-research sea lions at the Smithsonian Zoological Park (SNZ). Those data form the basis of the actuation motion of the robotic flipper presented here. The geometry of the robotic flipper is based a on high-resolution laser scan of a foreflipper of an adult female sea lion, scaled to about 60% of the full-scale flipper. The articulated model has three joints, mimicking the elbow, wrist and knuckle joint of the sea lion foreflipper. The robotic platform matches dynamics properties-Reynolds number and tip speed-of the animal when accelerating from rest. The robotic flipper can be used to determine the performance (forces and torques) and resulting flowfields.

Similarity Measures in Scientometric Research: The Jaccard Index versus Salton's Cosine Formula.

ERIC Educational Resources Information Center

Hamers, Lieve; And Others

1989-01-01

Describes two similarity measures used in citation and co-citation analysis--the Jaccard index and Salton's cosine formula--and investigates the relationship between the two measures. It is shown that Salton's formula yields a numerical value that is twice Jaccard's index in most cases, and an explanation is offered. (13 references) (CLB)

Chronostratigraphy of the Fish Creek-Vallecito Basin, SW Salton Trough: A High-Fidelity Record of Slip on the West Salton Detachment Fault and Subsidence in its Upper Plate

NASA Astrophysics Data System (ADS)

Dorsey, R. J.; Housen, B. A.; Janecke, S. U.; McDougall, K.; Fanning, M.; Fluette, A.; Axen, G. J.; Shirvell, C. R.

2006-12-01

The Fish Creek-Vallecito basin contains a 5.1-km thick section of sedimentary rocks in the SW Salton Trough that range in age from 8.1 to 0.9 Ma. The section preserves a record of basin subsidence related to slip on the West Salton detachment fault (WSDF), which formed the main western rift-flank structure of the Salton Trough. We obtained a well-constrained chronology from compilation of existing (Johnson et al., 1983) and new paleomagnetic data, ages of two tuffs high in the section, and thicknesses calculated from the geologic map of Winker (1987) and our work in the lower 1.3 km. The tuffs yielded SHRIMP U-Pb ages of 2.56 ± 0.09 and 2.54 ± 0.09 Ma from single zircons. Geohistory analysis, corrected for paleobathymetry and global sea- level change, yields a decompacted subsidence curve with 5 segments bounded by abrupt changes in subsidence rate: (1) 0.46 mm/yr from 8.1 to 5.5 Ma; (2) 1.8 mm/yr from 5.5 to 5.2 Ma; (3) zero subsidence or slight uplift from 5.2 to 4.6 Ma; (4) 1.9 mm/yr from 4.6 to 3.2 Ma; and (5) 0.4 mm/yr from 3.2 to 0.9 Ma. The base of the Elephant Trees Fm, dated here at 8.1 Ma, provides the earliest well dated record of extension in the SW Salton Trough. Earliest marine incursion is dated at 6.3 Ma, and the first appearance of Colorado River sand coincides closely with the Miocene-Pliocene boundary (5.33 Ma). Because the base of the marine Imperial Group does not coincide with a change in subsidence rate, we suggest that initial marine incursion resulted from a latest Miocene global sea-level highstand superposed on steady subsidence. Thus, the inflections at 8.1 and 5.5 Ma are the two most likely ages for onset of slip on the WSDF, but 4.6 Ma is also possible. Variations in subsidence rate are not predicted by models for extensional detachment faults, and may reflect episodic pulsed fault slip and/or long-wavelength folding related to dextral-wrench tectonics. Rapid subsidence in segment 4 began during progradation of the Colorado River

Prevalence of Urogenital Carcinoma in Stranded California Sea Lions ( Zalophus Californianus) from 2005-2015.

PubMed

Deming, Alissa C; Colegrove, Kathleen M; Duignan, Padraig J; Hall, Ailsa J; Wellehan, James F X; Gulland, Frances M D

2018-03-02

Urogenital carcinoma is common in wild California sea lions ( Zalophus californianus) along the west coast of the US. From 1979 to 1994, this cancer was observed in 18% (66/370) of necropsied subadult and adult sea lions at The Marine Mammal Center in Sausalito, California. A retrospective review of records from 1 January 2005 to 31 December 2015 was performed to characterize prevalence and characteristics of cancer over this decade. Fourteen percent (263/1917) of necropsied sea lions had cancer, of which 90% (237/263) were urogenital carcinoma. The prevalence of urogenital carcinoma was significantly higher in adults compared to juveniles and subadults. Advanced-stage disease with metastases was identified histologically in 78% (182/232) of cases and was the cause of death in 95% (172/182) of these cases. Metastases were most common in lung and lymph nodes, and hydronephrosis, secondary to ureter obstruction by metastases, was identified in 62% (114/185) of animals with advanced disease. No significant temporal change in prevalence was detected over the decade, and this highly aggressive, fatal cancer remains common in stranded California sea lions.

University of California Sea Grant College Program Directory 1974-1975.

ERIC Educational Resources Information Center

California Univ., San Diego, La Jolla. Inst. of Marine Resources.

The directory provides detailed information on the University of California Sea Grant programs dealing with management, education, and advisory services; coastal resources; agricultural research and development; fisheries research and development; as well as energy resources and development. (NTIS)

Apollo 9 Mission image - S0-65 Multispectral Photography - California

NASA Image and Video Library

2009-01-21

Earth Observation taken by the Apollo 9 crew. View is of Salton Sea and Imperial Valley in California. Latitude was 33.09 N by Longitude 116.14 W, Overlap was 50%, Altitude miles were 103 and cloud cover was 35%. This imagery taken as part of the NASA S0-65 Experiment "Multispectral Terrain Photography". The experiment provides simultaneous satellite photography of the Earth's surface in three distinct spectral bands. The photography consists of four almost spatially identical photographs. The images of ground objects appear in the same coordinate positions on all four photos in the multispectral set within the opto-mechanical tolerances of the Hasselblad cameras in the Apollo 9 spacecraft. Band designation for this frame is A. Film and filter is Ektachrome SO-368,Infrared Color Wratten 15. Mean Wavelength of Sensitivity is green,red and infrared. The Nominal Bandpass is total sensitivity of all dye layers 510-900nm.

Earth observation taken by the Expedition 35 crew

NASA Image and Video Library

2013-04-23

ISS035-E-027434 (23 April 2013) --- One of the Expedition 35 crew members aboard the Earth-orbiting International Space Station recorded this widespread image covering parts of Mexico, California and Nevada: Grand Canyon to Lake Mead and Las Vegas area (lower right corner), and westward to include the Gulf of California (beneath the docked Russian vehicle at upper left), the Salton Sea, Los Angeles Basin, and Great Valley.

The Effects of Rapid Sedimentation upon Continental Breakup: Kinematic and Thermal Modeling of the Salton Trough, Southern California, Based upon Recent Seismic Images

NASA Astrophysics Data System (ADS)

Han, L.; Hole, J. A.; Lowell, R. P.; Stock, J. M.; Fuis, G. S.

2016-12-01

The Salton Seismic Imaging Project (SSIP) illuminated crustal and upper mantle structure of the Salton Trough, the northern-most rift segment of the Gulf of California plate boundary. The crust is 17-18 km thick and homogeneous for 100 km in the plate motion direction. New crust is being created by distributed rift magmatism, Colorado River sedimentation, and metamorphism of the sediment. A 5 km thick pre-existing crustal layer may still exist. The crust has not broken apart to enable initiation of seafloor spreading. A one-dimensional time-dependent kinematic and thermal model was developed to simulate these observations. We assume that all crustal layers are stretched uniformly during extension. Distributed mafic magmatism and sedimentation are added simultaneously to compensate for the crustal thinning. The ratio of magmatism to sedimentation is constrained by the seismic observations. Heat is transported by thermal conduction and by advection due to stretching of the crust. A constant temperature boundary at the Moho is used to represent partial melting in the upper mantle. Assuming a constant plate motion rate, the zone of active rifting extends linearly with time. The crustal thickness and internal structure also evolve with time. The model constraints are the observed seismic structure and heat flow. The model rapidly reaches quasi-steady state, and could continue for many millions of years. The observed seismic structure and heat flow are reproduced after 3 Myr. The yield strength profile calculated from lithology and model temperature indicates that ductile deformation in the middle and lower crust dominates the crustal rheology. Rapid sedimentation delays crustal breakup and the initiation of seafloor spreading by maintaining the thickness of the crust and keeping it predominantly ductile. This process probably occurs wherever a large river flows into an active rift driven by far-field extension. It may have built passive margins in many locations

Analysis of earthquake clustering and source spectra in the Salton Sea Geothermal Field

NASA Astrophysics Data System (ADS)

Cheng, Y.; Chen, X.

2015-12-01

The Salton Sea Geothermal field is located within the tectonic step-over between San Andreas Fault and Imperial Fault. Since the 1980s, geothermal energy exploration has resulted with step-like increase of microearthquake activities, which mirror the expansion of geothermal field. Distinguishing naturally occurred and induced seismicity, and their corresponding characteristics (e.g., energy release) is important for hazard assessment. Between 2008 and 2014, seismic data recorded by a local borehole array were provided public access from CalEnergy through SCEC data center; and the high quality local recording of over 7000 microearthquakes provides unique opportunity to sort out characteristics of induced versus natural activities. We obtain high-resolution earthquake location using improved S-wave picks, waveform cross-correlation and a new 3D velocity model. We then develop method to identify spatial-temporally isolated earthquake clusters. These clusters are classified into aftershock-type, swarm-type, and mixed-type (aftershock-like, with low skew, low magnitude and shorter duration), based on the relative timing of largest earthquakes and moment-release. The mixed-type clusters are mostly located at 3 - 4 km depth near injection well; while aftershock-type clusters and swarm-type clusters also occur further from injection well. By counting number of aftershocks within 1day following mainshock in each cluster, we find that the mixed-type clusters have much higher aftershock productivity compared with other types and historic M4 earthquakes. We analyze detailed spatial variation of 'b-value'. We find that the mixed-type clusters are mostly located within high b-value patches, while large (M>3) earthquakes and other types of clusters are located within low b-value patches. We are currently processing P and S-wave spectra to analyze the spatial-temporal correlation of earthquake stress parameter and seismicity characteristics. Preliminary results suggest that the

Sea level, paleogeography, and archeology on California's Northern Channel Islands

NASA Astrophysics Data System (ADS)

Reeder-Myers, Leslie; Erlandson, Jon M.; Muhs, Daniel R.; Rick, Torben C.

2015-03-01

Sea-level rise during the late Pleistocene and early Holocene inundated nearshore areas in many parts of the world, producing drastic changes in local ecosystems and obscuring significant portions of the archeological record. Although global forces are at play, the effects of sea-level rise are highly localized due to variability in glacial isostatic adjustment (GIA) effects. Interpretations of coastal paleoecology and archeology require reliable estimates of ancient shorelines that account for GIA effects. Here we build on previous models for California's Northern Channel Islands, producing more accurate late Pleistocene and Holocene paleogeographic reconstructions adjusted for regional GIA variability. This region has contributed significantly to our understanding of early New World coastal foragers. Sea level that was about 80-85 m lower than present at the time of the first known human occupation brought about a landscape and ecology substantially different than today. During the late Pleistocene, large tracts of coastal lowlands were exposed, while a colder, wetter climate and fluctuating marine conditions interacted with rapidly evolving littoral environments. At the close of the Pleistocene and start of the Holocene, people in coastal California faced shrinking land, intertidal, and subtidal zones, with important implications for resource availability and distribution.

Earth Observation

NASA Image and Video Library

2014-06-14

ISS040-E-011868 (14 June 2014) --- The dark waters of the Salton Sea stand out against neighboring cultivation and desert sands in the middle of the Southern California desert, as photographed by one of the Expedition 40 crew members aboard the Earth-orbiting International Space Station on June 14, 2014.

Infection of California sea lions (Zalophus californianus) with terrestrial Brucella spp.

PubMed

Avalos-Téllez, Rosalía; Ramírez-Pfeiffer, Carlos; Hernández-Castro, Rigoberto; Díaz-Aparicio, Efrén; Sánchez-Domínguez, Carlos; Zavala-Norzagaray, Alan; Arellano-Reynoso, Beatriz; Suárez-Güemes, Francisco; Aguirre, A Alonso; Aurioles-Gamboa, David

2014-10-01

Infections with Brucella ceti and pinnipedialis are prevalent in marine mammals worldwide. A total of 22 California sea lions (Zalophus californianus) were examined to determine their exposure to Brucella spp. at San Esteban Island in the Gulf of California, Mexico, in June and July 2011. Although samples of blood, vaginal mucus and milk cultured negative for these bacteria, the application of rose Bengal, agar gel immunodiffusion, PCR and modified fluorescence polarization assays found that five animals (22.7%) had evidence of exposure to Brucella strains. The data also suggested that in two of these five sea lions the strains involved were of terrestrial origin, a novel finding in marine mammals. Further work will be required to validate and determine the epidemiological significance of this finding. Copyright © 2014 Elsevier Ltd. All rights reserved.

Two novel noroviruses and a novel norovirus genogroup in California sea lions.

PubMed

Teng, Jade L L; Martelli, Paolo; Chan, Wan-Mui; Lee, Hwei Huih; Hui, Suk-Wai; Lau, Candy C Y; Tse, Herman; Yuen, Kwok-Yung; Lau, Susanna K P; Woo, Patrick C Y

2018-06-01

In this study, two novel noroviruses (NoVs) were discovered from faecal samples from California sea lions from an oceanarium in Hong Kong, and named California sea lion NoV 1 (Csl/NoV1) and California sea lion NoV 2 (Csl/NoV2). Whole-genome sequencing showed that the genome organization and amino acid motifs of both Csl/NoV1 and Csl/NoV2 were typical of those of other NoVs in their open reading frames (ORFs). Csl/NoV1 possessed only 52.6-52.8 % amino acid identity in VP1 to the closest matches in genogroup GII. Therefore, Csl/NoV1 should constitute a novel genogroup of NoV. Shifting of the phylogenetic position of Csl/NoV1 in the RdRp, VP1 and VP2 trees was observed, which may have been due to recombination events and/or biased mutations. Csl/NoV2 possessed 55.4-56.2 % amino acid identity in VP1 to its closest relatives in genogroup GVI, which means that it represents a new genotype in genogroup GVI. Further studies will reveal what diseases these NoVs can cause in marine mammals.

PHARMACOKINETICS OF SINGLE-DOSE ORALLY ADMINISTERED CIPROFLOXACIN IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).

PubMed

Barbosa, Lorraine; Johnson, Shawn P; Papich, Mark G; Gulland, Frances

2015-06-01

Ciprofloxacin is commonly selected for clinical use due to its broad-spectrum efficacy and is a frequently administered antibiotic at The Marine Mammal Center, a marine mammal rehabilitation facility. Ciprofloxacin is used for treatment of California sea lions ( Zalophus californianus ) suffering from a variety of bacterial infections at doses extrapolated from other mammalian species. However, as oral absorption is variable both within and across species, a more accurate determination of appropriate dosage is needed to ensure effective treatment and avoid emergence of drug-resistant bacterial strains. A pharmacokinetic study was performed to assess plasma concentrations of ciprofloxacin in California sea lions after a single oral dose. Twenty healthy California sea lions received a single 10-mg/kg oral dose of ciprofloxacin administered in a herring fish. Blood was then collected at two of the following times from each individual: 0.5, 0.75, 1, 2, 4, 8, 10, 12, 18, and 24 hr postingestion. Plasma ciprofloxacin concentration was assessed via high-performance liquid chromatography. A population pharmacokinetics model demonstrated that an oral ciprofloxacin dose of 10 mg/kg achieved an area under the concentration vs. time curve of 6.01 μg hr/ml. Absorption was rapid, with ciprofloxacin detectable in plasma 0.54 hr after drug administration; absorption half-life was 0.09 hr. A maximum plasma concentration of 1.21 μg/ml was observed at 1.01 hr, with an elimination half-life of 3.09 hr. Ciprofloxacin administered orally at 10 mg/kg produced therapeutic antibacterial exposure for only some of the most susceptible bacterial organisms commonly isolated from California sea lions.

Geothermal resources of California sedimentary basins

USGS Publications Warehouse

Williams, C.F.; Grubb, F.V.; Galanis, S.P.

2004-01-01

The 2004 Department of Energy (DOE) Strategic Plan for geothermal energy calls for expanding the geothermal resource base of the United States to 40,000 MW of electric power generating potential. This will require advances in technologies for exploiting unconventional geothermal resources, including Enhanced Geothermal Systems (EGS) and geopressured geothermal. An investigation of thermal conditions in California sedimentary basins through new temperature and heat flow measurements reveals significant geothermal potential in some areas. In many of the basins, the combined cooling effects of recent tectonic and sedimentary processes result in relatively low (<60 mW/m2) heat flow and geothermal gradients. For example, temperatures in the upper 3 km of San Joaquin, Sacramento and Ventura basins are typically less than 125??C and do not reach 200??c by 5 km. By contrast, in the Cuyama, Santa Maria and western Los Angeles basins, heat flow exceeds 80 mW/m2 and temperatures near or above 200??C occur at 4 to 5 km depth, which represents thermal conditions equivalent to or hotter than those encountered at the Soultz EGS geothermal site in Europe. Although the extractable geothermal energy contained in these basins is not large relative to the major California producing geothermal fields at The Geysers or Salton Sea, the collocation in the Los Angeles basin of a substantial petroleum extraction infrastructure and a major metropolitan area may make it attractive for eventual geothermal development as EGS technology matures.

Sea level, paleogeography, and archeology on California's Northern Channel Islands

USGS Publications Warehouse

Reeder-Myers, Leslie; Erlandson, Jon M.; Muhs, Daniel R.; Rick, Torben C.

2015-01-01

Sea-level rise during the late Pleistocene and early Holocene inundated nearshore areas in many parts of the world, producing drastic changes in local ecosystems and obscuring significant portions of the archeological record. Although global forces are at play, the effects of sea-level rise are highly localized due to variability in glacial isostatic adjustment (GIA) effects. Interpretations of coastal paleoecology and archeology require reliable estimates of ancient shorelines that account for GIA effects. Here we build on previous models for California's Northern Channel Islands, producing more accurate late Pleistocene and Holocene paleogeographic reconstructions adjusted for regional GIA variability. This region has contributed significantly to our understanding of early New World coastal foragers. Sea level that was about 80–85 m lower than present at the time of the first known human occupation brought about a landscape and ecology substantially different than today. During the late Pleistocene, large tracts of coastal lowlands were exposed, while a colder, wetter climate and fluctuating marine conditions interacted with rapidly evolving littoral environments. At the close of the Pleistocene and start of the Holocene, people in coastal California faced shrinking land, intertidal, and subtidal zones, with important implications for resource availability and distribution.

Relation of desert pupfish abundance to selected environmental variables in natural and manmade habitats in the Salton Sea basin

USGS Publications Warehouse

Martin, B.A.; Saiki, M.K.

2005-01-01

We assessed the relation between abundance of desert pupfish, Cyprinodon macularius, and selected biological and physicochemical variables in natural and manmade habitats within the Salton Sea Basin. Field sampling in a natural tributary, Salt Creek, and three agricultural drains captured eight species including pupfish (1.1% of the total catch), the only native species encountered. According to Bray-Curtis resemblance functions, fish species assemblages differed mostly between Salt Creek and the drains (i.e., the three drains had relatively similar species assemblages). Pupfish numbers and environmental variables varied among sites and sample periods. Canonical correlation showed that pupfish abundance was positively correlated with abundance of western mosquitofish, Gambusia affinis, and negatively correlated with abundance of porthole livebearers, Poeciliopsis gracilis, tilapias (Sarotherodon mossambica and Tilapia zillii), longjaw mudsuckers, Gillichthys mirabilis, and mollies (Poecilia latipinnaandPoecilia mexicana). In addition, pupfish abundance was positively correlated with cover, pH, and salinity, and negatively correlated with sediment factor (a measure of sediment grain size) and dissolved oxygen. Pupfish abundance was generally highest in habitats where water quality extremes (especially high pH and salinity, and low dissolved oxygen) seemingly limited the occurrence of nonnative fishes. This study also documented evidence of predation by mudsuckers on pupfish. These findings support the contention of many resource managers that pupfish populations are adversely influenced by ecological interactions with nonnative fishes. ?? Springer 2005.

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

CRYPTOMONADS FROM THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Regional Sea Level Variation: California Coastal Subsidence (Invited)

NASA Astrophysics Data System (ADS)

Blewitt, G.; Hammond, W. C.; Nerem, R.

2013-12-01

Satellite altimetry over the last two decades has measured variations in geocentric sea level (GSL), relative to the Earth system center of mass, providing valuable data to test models of physical oceanography and the effects of global climate change. The societal impacts of sea level change however relate to variations in local sea level (LSL), relative to the land at the coast. Therefore, assessing the impacts of sea level change requires coastal measurements of vertical land motion (VLM). Indeed, ΔLSL = ΔGSL - ΔVLM, with subsidence mapping 1:1 into LSL. Measurements of secular coastal VLM also allow tide-gauge data to test models of GSL over the last century in some locations, which cannot be provided by satellite data. Here we use GPS geodetic data within 15 km of the US west coast to infer regional, secular VLM. A total of 89 GPS stations met the criteria that time series span >4.5 yr, and do not have obvious non-linear variation, as may be caused by local instability. VLM rates for the GPS stations are derived in the secular reference frame ITRF2008, which aligns with the Earth system center of mass to ×0.5 mm/yr. We find that regional VLM has different behavior north and south of the Mendocino Triple Junction (MTJ). The California coast has a coherent regional pattern of subsidence averaging 0.5 mm/yr, with an increasing trend to the north. This trend generally matches GIA model predictions. Around San Francisco Bay, the observed coastal subsidence of 1.0 mm/yr coherently decreases moving away from the Pacific Ocean to very small subsidence on the east shores of the bay. This gradient is likely caused by San Andreas-Hayward Fault tectonics, and possibly by differential surface loading across the bay and Sacramento-San Joachim River Delta. Thus in addition to the trend in subsidence from GIA going northward along the California coast, tectonics may also play a role where the plate boundary fault system approaches the coast. In contrast, we find that VLM

Chlorinated, brominated, and perfluorinated compounds, polycyclic aromatic hydrocarbons and trace elements in livers of sea otters from California, Washington, and Alaska (USA), and Kamchatka (Russia)

USGS Publications Warehouse

Kannan, K.; Moon, H.-B.; Yun, S.-H.; Agusa, T.; Thomas, N.J.; Tanabe, S.

2008-01-01

Concentrations of organochlorine pesticides (DDTs, HCHs, and chlordanes), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), perfluorinated compounds (PFCs), and 20 trace elements were determined in livers of 3- to 5-year old stranded sea otters collected from the coastal waters of California, Washington, and Alaska (USA) and from Kamchatka (Russia). Concentrations of organochlorine pesticides, PCBs, and PBDEs were high in sea otters collected from the California coast. Concentrations of DDTs were 10-fold higher in California sea otters than in otters from other locations; PCB concentrations were 5-fold higher, and PBDE concentrations were 2-fold higher, in California sea otters than in otters from other locations. Concentrations of PAHs were higher in sea otters from Prince William Sound than in sea otters from other locations. Concentrations of several trace elements were elevated in sea otters collected from California and Prince William Sound. Elevated concentrations of Mn and Zn in sea otters from California and Prince William Sound were indicative of oxidative stress-related injuries in these two populations. Concentrations of all of the target compounds, including trace elements, that were analyzed in sea otters from Kamchatka were lower than those found from the US coastal locations. ?? The Royal Society of Chemistry.

Diagnosis and treatment of Sarcocystis neurona-induced myositis in a free-ranging California sea lion.

PubMed

Carlson-Bremer, Daphne P; Gulland, Frances M D; Johnson, Christine K; Colegrove, Kathleen M; Van Bonn, William G

2012-02-01

An underweight, lethargic adult female California sea lion (Zalophus californianus) became stranded along the California shore and was captured and transported to a rehabilitation hospital for assessment and care. Initial physical assessment revealed the sea lion was lethargic and in poor body condition. Active myositis was diagnosed on the basis of concurrent elevations in activities of alanine aminotransferase and creatine kinase detected during serum biochemical analysis. Infection with Sarcocystis neurona was diagnosed after serologic titers increased 4-fold over a 3-week period. Diagnosis was confirmed on the basis of histopathologic findings, positive results on immunohistochemical staining, and results of quantitative PCR assay on biopsy specimens obtained from the diaphragm and muscles of the dorsal cervical region. Anticoccidial treatment was instituted with ponazuril (10 mg/kg [4.5 mg/lb], PO, q 24 h) and continued for 28 days. Prednisone (0.2 mg/kg [0.09 mg/lb], PO, q 12 h) was administered for 2 days and then every 24 hours for 5 days to treat associated inflammation. At the end of treatment, the sea lion was clinically normal, alanine aminotransferase and creatine kinase values were within reference limits, and antibody titers against S neurona had decreased 6-fold. The sea lion was released approximately 3 months after becoming stranded. S neurona-induced myositis was diagnosed in a free-ranging California sea lion. On the basis of the successful treatment and release of this sea lion, anticoccidial treatment should be considered for marine mammals in which protozoal disease is diagnosed.

Projecting Future Sea Level Rise for Water Resources Planning in California

NASA Astrophysics Data System (ADS)

Anderson, J.; Kao, K.; Chung, F.

2008-12-01

Sea level rise is one of the major concerns for the management of California's water resources. Higher water levels and salinity intrusion into the Sacramento-San Joaquin Delta could affect water supplies, water quality, levee stability, and aquatic and terrestrial flora and fauna species and their habitat. Over the 20th century, sea levels near San Francisco Bay increased by over 0.6ft. Some tidal gauge and satellite data indicate that rates of sea level rise are accelerating. Sea levels are expected to continue to rise due to increasing air temperatures causing thermal expansion of the ocean and melting of land-based ice such as ice on Greenland and in southeastern Alaska. For water planners, two related questions are raised on the uncertainty of future sea levels. First, what is the expected sea level at a specific point in time in the future, e.g., what is the expected sea level in 2050? Second, what is the expected point of time in the future when sea levels will exceed a certain height, e.g., what is the expected range of time when the sea level rises by one foot? To address these two types of questions, two factors are considered: (1) long term sea level rise trend, and (2) local extreme sea level fluctuations. A two-step approach will be used to develop sea level rise projection guidelines for decision making that takes both of these factors into account. The first step is developing global sea level rise probability distributions for the long term trends. The second step will extend the approach to take into account the effects of local astronomical tides, changes in atmospheric pressure, wind stress, floods, and the El Niño/Southern Oscillation. In this paper, the development of the first step approach is presented. To project the long term sea level rise trend, one option is to extend the current rate of sea level rise into the future. However, since recent data indicate rates of sea level rise are accelerating, methods for estimating sea level rise

Assessing Temperature Risk to Crab in the Northeast Pacific (Southern California to the Beaufort Sea)

EPA Science Inventory

To evaluate the vulnerability of the Brachyura crabs (<200 m) to projected increases in sea surface temperature (SST), we developed an approach that evaluates risk within each of the ten Marine Ecoregions of the World (MEOW) ranging from Southern California to the Beaufort Sea...

IDENTIFICATION OF TWO NOVEL COCCIDIAN SPECIES SHED BY CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS)

PubMed Central

Carlson-Bremer, Daphne; Johnson, Christine K.; Miller, Robin H.; Gulland, Frances M. D.; Conrad, Patricia A.; Wasmuth, James D.; Colegrove, Kathleen M.

2016-01-01

Routine fecal examination revealed novel coccidian oocysts in asymptomatic California sea lions (Zalophus californianus) in a rehabilitation facility. Coccidian oocysts were observed in fecal samples collected from 15 of 410 California sea lions admitted to The Marine Mammal Center between April 2007 and October 2009. Phylogenetic analysis using the full ITS-1 region, partial small subunit 18S rDNA sequence, and the Apicomplexa rpoB region identified 2 distinct sequence clades, referred to as Coccidia A and Coccidia B, and placed them in the Sarcocystidae, grouped with the tissue-cyst–forming coccidia. Both sequence clades resolved as individual taxa at ITS-1 and rpoB and were most closely related to Neospora caninum. Coccidia A was identified in 11 and Coccidia B in 4 of 12 sea lion oocyst samples successfully sequenced (3 of those sea lions were co-infected with both parasites). Shedding of Coccidia A oocysts was not associated with age class, sex, or stranding location, but yearlings represented the majority of shedders (8/15). This is the first study to use molecular phylogenetics to identify and describe coccidian parasites shed by a marine mammal. PMID:22091999

Identification of two novel coccidian species shed by California sea lions (Zalophus californianus).

PubMed

Carlson-Bremer, Daphne; Johnson, Christine K; Miller, Robin H; Gulland, Frances M D; Conrad, Patricia A; Wasmuth, James D; Colegrove, Kathleen M; Grigg, Michael E

2012-04-01

Routine fecal examination revealed novel coccidian oocysts in asymptomatic California sea lions (Zalophus californianus) in a rehabilitation facility. Coccidian oocysts were observed in fecal samples collected from 15 of 410 California sea lions admitted to The Marine Mammal Center between April 2007 and October 2009. Phylogenetic analysis using the full ITS-1 region, partial small subunit 18S rDNA sequence, and the Apicomplexa rpoB region identified 2 distinct sequence clades, referred to as Coccidia A and Coccidia B, and placed them in the Sarcocystidae, grouped with the tissue-cyst-forming coccidia. Both sequence clades resolved as individual taxa at ITS-1 and rpoB and were most closely related to Neospora caninum. Coccidia A was identified in 11 and Coccidia B in 4 of 12 sea lion oocyst samples successfully sequenced (3 of those sea lions were co-infected with both parasites). Shedding of Coccidia A oocysts was not associated with age class, sex, or stranding location, but yearlings represented the majority of shedders (8/15). This is the first study to use molecular phylogenetics to identify and describe coccidian parasites shed by a marine mammal.

Characterizing potentially induced earthquake rate changes in the Brawley Seismic Zone, southern California

USGS Publications Warehouse

Llenos, Andrea L.; Michael, Andrew J.

2016-01-01

The Brawley seismic zone (BSZ), in the Salton trough of southern California, has a history of earthquake swarms and geothermal energy exploitation. Some earthquake rate changes may have been induced by fluid extraction and injection activity at local geothermal fields, particularly at the North Brawley Geothermal Field (NBGF) and at the Salton Sea Geothermal Field (SSGF). We explore this issue by examining earthquake rate changes and interevent distance distributions in these fields. In Oklahoma and Arkansas, where considerable wastewater injection occurs, increases in background seismicity rate and aftershock productivity and decreases in interevent distance were indicative of fluid‐injection‐induced seismicity. Here, we test if similar changes occur that may be associated with fluid injection and extraction in geothermal areas. We use stochastic epidemic‐type aftershock sequence models to detect changes in the underlying seismogenic processes, shown by statistically significant changes in the model parameters. The most robust model changes in the SSGF roughly occur when large changes in net fluid production occur, but a similar correlation is not seen in the NBGF. Also, although both background seismicity rate and aftershock productivity increased for fluid‐injection‐induced earthquake rate changes in Oklahoma and Arkansas, the background rate increases significantly in the BSZ only, roughly corresponding with net fluid production rate increases. Moreover, in both fields the interevent spacing does not change significantly during active energy projects. This suggests that, although geothermal field activities in a tectonically active region may not significantly change the physics of earthquake interactions, earthquake rates may still be driven by fluid injection or extraction rates, particularly in the SSGF.

Seismic Reflectivity of the Crust in the Northern Salton Trough

NASA Astrophysics Data System (ADS)

Bauer, K.; Fuis, G. S.; Goldman, M.; Persaud, P.; Ryberg, T.; Langenheim, V. E.; Scheirer, D. S.; Rymer, M. J.; Hole, J. A.; Stock, J. M.; Catchings, R.

2015-12-01

The Salton Trough in southern California is a tectonically active pull-apart basin that was formed by migrating step-overs between strike-slip faults, of which the San Andreas Fault (SAF) and the Imperial Fault are the current, northernmost examples. The Salton Seismic Imaging Project (SSIP) was undertaken to improve our knowledge of fault geometry and seismic velocities within the sedimentary basins and underlying crystalline crust around the SAF. Such data are useful as input for modeling scenarios of strong ground shaking in the surrounding high-population areas. We used pre-stack depth migration of line segments from shot gathers in several seismic profiles that were acquired in the northern part of the SSIP study area (Lines 4 - 7). Our migration approach can be considered as an infinite-frequency approximation of the Fresnel volume pre-stack depth migration method. We use line segments instead of the original waveform data. We demonstrate the method using synthetic data and analyze real data from Lines 4 - 7 to illustrate the relationship between distinct phases in the time domain and their resulting image at depth. We show both normal-moveout reflections from sub-horizontal interfaces and reverse-moveout reflections from steep interfaces, such as faults. Migrated images of dipping faults, such as the SAF and the Pinto Mountain Fault, are presented in this way. The SAF is imaged along Line 4, through the Mecca Hills, as a number of steeply dipping fault segments that collectively form a flower structure, above 5 km depth, that sole into a moderately NE-dipping fault below that depth. The individual migrated reflection packages correlate with mapped surface fault traces in the Mecca Hills. A similar geometry is seen on Line 6, from Palm Springs through Yucca Valley, where fault splays sole or project into a moderately dipping SAF below 10-km depth. We also show and discuss the reflectivity pattern of the middle and lower crust for Lines 4 - 7.

Implications of Deoxygenation and Acidification for Deep Sea Urchins in Southern California

NASA Astrophysics Data System (ADS)

Sato, Kirk Nicholas Suda

Implications of multiple climate drivers for sea urchins were investigated across a spectrum of biological organization ranging from the urchin guild scale, to individual life history traits, to the geochemistry, material properties and porosity of sea urchin calcium carbonate skeletal tests. Using pink fragile sea urchins (Strongylocentrotus fragilis) on the southern California upwelling margin as a model species, links between biological traits and environmental parameters in nature across multiple spatial and temporal scales revealed correlations with dissolved oxygen (DO), pH, and temperature. Temporal trends in sea urchin populations assessed from trawl surveys conducted in southern California over the last 20 years (1994-2013) revealed changes in deep-sea urchin densities and depth distributions that coincide with trends in DO and pH on multidecadal and interdecadal (El Nino Southern Oscillation) time scales. The shallower urchin species ( Lytechinus pictus) decreased in density in the upper 200 m by 80%, and the deeper S. fragilis increased in density by ˜300%, providing the first evidence of habitat compression and expansion in sea urchin populations associated with secular and interdecadal variability in DO and pH. In this context, marketable food quality properties of the roe were compared between S. fragilis and the currently fished California red urchin, Mesocentrotus franciscanus, to assess the feasibility of developing a climate change-tolerant future S. fragilis trap fishery. Although roe color, texture, and resilience were similar between the two species, smaller and softer S. fragilis roe suggest it may only supplement, but not replace M. franciscanus in future fisheries. In comparisons across natural margin depth and climate gradients from 100-1100 m, S. fragilis exhibited reduced gonad production, smaller, weaker and more porous calcified tests in the Oxygen Minimum Zone (DO < 22 mumol kg-1) and pH Minimum Zone (in situ pHTotal <7.57) than those

Organochlorine pesticides and polychlorinated biphenyls in California sea lions (Zalophus californianus californianus) from the Gulf of California, México.

PubMed

Niño-Torres, Carlos Alberto; Gardner, Susan C; Zenteno-Savín, Tania; Ylitalo, Gina M

2009-02-01

We report concentrations of several classes of organochlorines (OCs) in the blubber of California sea lions (Zalophus californianus) from the Gulf of California. Summed OC levels measured in 34 wild-ranging animals were, in general, lower than those previously reported in sea lions from the eastern Pacific. The rank order of OCs was SigmaDDTs (mean=3400 ng g(-1 ) lipid weight [lw]) > SigmaPCBs (1400 ng g(-1 ) lw) > SigmaHCHs (50 ng g(-1 ) lw) >or= SigmaCHLORs (46 ng g(-1 ) lw). The most abundant OC measured was the DDT metabolite, p,p'-DDE. No significant differences in OC profiles were found between genders or rookeries. Although the mean concentrations of OCs measured in adult males and females were similar, only adult females had significantly higher (p<0.05) mean blubber concentrations of summation SigmaDDTs and summation SigmaHCHs than pups.

Teleseismic surface wave study of S-wave velocity structure in Southern California

NASA Astrophysics Data System (ADS)

Prindle-Sheldrake, K. L.; Tanimoto, T.

2002-12-01

We report on a 3D S-wave velocity structure derived from teleseismic Rayleigh and Love waves using TriNet broadband seismic data. Phase velocity maps, constructed between 20 and 55 mHz for Rayleigh waves and between 25 and 45 mHz for Love waves, were inverted for S-wave velocity structure at depth. Our starting model is SCEC 2.2, which has detailed crustal structure, but laterally homogeneous upper mantle structure. Depth resolution from the data set is good from the surface to approximately 100 km, but deteriorates rapidly beyond this depth. Our analysis indicates that, while Rayleigh wave data are mostly sensitive to mantle structure, Love wave data require some modifications of crustal structure from SCEC 2.2 model. Various regions in Southern California have different seismic-velocity signatures in terms of fast and slow S-wave velocities: In the Southern Sierra, both the crust and mantle are slow. In the Mojave desert, mid-crustal depths tend to show slow velocities, which are already built into SCEC 2.2. In the Transverse Ranges, the lower crust and mantle are both fast. Our Love wave results require much faster crustal velocity than those in SCEC 2.2 in this region. In the Peninsular ranges, both the crust and mantle are fast with mantle fast velocity extending to about 70 km. This is slightly more shallow than the depth extent under the Transverse Ranges, yet it is surprisingly deep. Under the Salton Sea, the upper crust is very slow and the upper mantle is also slow. However, these two slow velocity layers are separated by faster velocity lower crust which creates a distinct contrast with respect to the adjacent slow velocity regions. Existence of such a relatively fast layer, sandwiched by slow velocities, are related to features in phase velocity maps, especially in the low frequency Love wave phase velocity map (25 mHz) and the high frequency Rayleigh wave phase velocity maps (above 40 mHz). Such a feature may be related to partial melting processes

Determination of sound types and source levels of airborne vocalizations by California sea lions, Zalophus californianus, in rehabilitation at the Marine Mammal Center in Sausalito, California

NASA Astrophysics Data System (ADS)

Schwalm, Afton Leigh

California sea lions (Zalophus californianus) are a highly popular and easily recognized marine mammal in zoos, aquariums, circuses, and often seen by ocean visitors. They are highly vocal and gregarious on land. Surprisingly, little research has been performed on the vocalization types, source levels, acoustic properties, and functions of airborne sounds used by California sea lions. This research on airborne vocalizations of California sea lions will advance the understanding of this aspect of California sea lions communication, as well as examine the relationship between health condition and acoustic behavior. Using a PhillipsRTM digital recorder with attached microphone and a calibrated RadioShackRTM sound pressure level meter, acoustical data were recorded opportunistically on California sea lions during rehabilitation at The Marine Mammal Center in Sausalito, CA. Vocalizations were analyzed using frequency, time, and amplitude variables with Raven Pro: Interactive Sound Analysis Software Version 1.4 (The Cornell Lab of Ornithology, Ithaca, NY). Five frequency, three time, and four amplitude variables were analyzed for each vocalization. Differences in frequency, time, and amplitude variables were not significant by sex. The older California sea lion group produced vocalizations that were significantly lower in four frequency variables, significantly longer in two time variables, significantly higher in calibrated maximum and minimum amplitude variables, and significantly lower in frequency at maximum and minimum amplitude compared with pups. Six call types were identified: bark, goat, growl/grumble, bark/grumble, bark/growl, and grumble/moan. The growl/grumble call was higher in dominant beginning, ending, and minimum frequency, as well as in the frequency at maximum amplitude compared with the bark, goat, bark/grumble calls in the first versus last vocalization sample. The goat call was significantly higher in first harmonic interval than any other call type

Aerodynamic Tests on a Static California Sea Lion Flipper

NASA Astrophysics Data System (ADS)

Kulkarni, Aditya A.; Leftwich, Megan C.

2017-11-01

Unlike most biological swimmers that use BCF swimming, the California sea lion relies on its foreflippers for thrust production. This unique swimming style, which lacks a characteristic oscillation frequency, allows the sea lion to leave less traceable wake while also producing high amounts of thrust. While the swimming energetics of the animal have been studied, almost nothing is known about the fluid dynamics of the system. To overcome this lack of basic understanding, a three-dimensional model of the flipper was developed using structured light-based scanners. Cross sections of the flipper model resemble the shape of the airfoils typically found in wings with thickness ratios, 11% - 37%. Wind tunnel testing conducted on static flipper revealed that positive lift was being generated at negative angles of attack. This is hypothesized to help the sea lions considerably in perform tight maneuvers with a small turning radius. The wake structure downstream of the flipper was captured using Particle Image Velocimetry (PIV).

Comparative biology of Uncinaria spp. in the California sea lion (Zalophus californianus) and the northern fur seal (Callorhinus ursinus) in California.

PubMed

Lyons, E T; DeLong, R L; Gulland, F M; Melin, S R; Tolliver, S C; Spraker, T R

2000-12-01

Studies on several aspects of the life cycle of hookworms (Uncinaria spp.) in the California sea lion (Zalophus californianus) and northern fur seal (Callorhinus ursinus) were conducted on material collected on San Miguel Island (SMI), California and at The Marine Mammal Center, Sausalito, California in 1997, 1998, and 1999. Examination of Z. californianus intestines for adult hookworms and feces for eggs revealed that longevity of these parasites in pups is about 6-8 mo, and infections are probably not present in older sea lions. Parasitic third-stage larvae (L3) were recovered from the ventral abdominal tissue of Z. californianus, suggesting transmammary transmission. Callorhinus ursinus pups had no hookworm eggs in their feces or adult worms (except for 1 probable contaminant) in their intestines in the fall and early winter, revealing that adult Uncinaria spp. are spontaneously lost at <3 mo of age of the pups. Sand samples from rookeries, used by both Z. californianus and C. ursinus, on SMI were negative for free-living, L3 in summer months but positive in fall and winter months, indicating seasonality occurred.

Underwater psychophysical audiogram of a young male California sea lion (Zalophus californianus).

PubMed

Mulsow, Jason; Houser, Dorian S; Finneran, James J

2012-05-01

Auditory evoked potential (AEP) data are commonly obtained in air while sea lions are under gas anesthesia; a procedure that precludes the measurement of underwater hearing sensitivity. This is a substantial limitation considering the importance of underwater hearing data in designing criteria aimed at mitigating the effects of anthropogenic noise exposure. To determine if some aspects of underwater hearing sensitivity can be predicted using rapid aerial AEP methods, this study measured underwater psychophysical thresholds for a young male California sea lion (Zalophus californianus) for which previously published aerial AEP thresholds exist. Underwater thresholds were measured in an aboveground pool at frequencies between 1 and 38 kHz. The underwater audiogram was very similar to those previously published for California sea lions, suggesting that the current and previously obtained psychophysical data are representative for this species. The psychophysical and previously measured AEP audiograms were most similar in terms of high-frequency hearing limit (HFHL), although the underwater HFHL was sharper and occurred at a higher frequency. Aerial AEP methods are useful for predicting reductions in the HFHL that are potentially independent of the testing medium, such as those due to age-related sensorineural hearing loss.

At-sea distribution and abundance of seabirds off southern California: A 20-year comparison

USGS Publications Warehouse

Mason, J.W.; McChesney, G.J.; McIver, W.R.; Carter, H.R.; Takekawa, John Y.; Golightly, R.T.; Ackerman, Joshua T.; Orthmeyer, D.L.; Perry, W.M.; Yee, J.L.; Pierson, M.O.; McCrary, M.D.

2007-01-01

We conducted aerial at-sea and coastal surveys to examine the distribution and abundance of seabirds off southern California, from Cambria, California, to the Mexican border. From May 1999-January 2002, we flew 102 d, covered >54,640 km of transect lines, and conducted nine complete surveys of southern California in January, May, and September. We identified 54 species comprising 12 families and counted >135,000 individuals. Seabird densities were greater along island and mainland coastlines than at sea and were usually greatest in January surveys. Densities were greatest at sea near the northern Channel Islands in January and north of Point Conception in May, and lowest in the southwestern portion of the Southern California Bight in all survey months. On coastal transects, seabird densities were greatest along central and southern portions of the mainland coastline from Point Arguello to Mexico. We estimated that 981,000 ?? 144,000 (x?? ?? SE) seabirds occurred in the study area in January, 862,000 ?? 95,000 in May, and 762,000 ?? 72,000 in September. California Gulls (Larus californicus), Western Grebes (Aechmophorus occidentalis), and Cassin's Auklets (Ptychoramphus aleuticus) were most abundant in January surveys at sea, whereas Sooty and Short-tailed shearwaters (Puffinus griseus and P. tenuirostris), phalaropes (Phalaropus spp.), and Western Gulls (Larus. occidentalis) were most abundant in May and September surveys. On coastal transects, California Gulls, Western Grebes, Western Gulls, and Surf Scoters (Melanitta perspicillata) were most abundant in January; Western Grebes, Western Gulls, Surf Scoters, and Brown Pelicans (Pelecanus occidentalis) were most abundant in May; and Sooty Shearwaters, Short-tailed Shearwaters, Western Gulls, Western Grebes, Brown Pelicans, and Heermann's Gulls (Larus heermanni) were most abundant in September. Compared to historical seabird densities collected in the same area two decades ago (1975-1978 and 1980-1983), abundance

Epidemiology and pathology of Toxoplasma gondii in free-ranging California sea lions (Zalophus californianus).

PubMed

Carlson-Bremer, Daphne; Colegrove, Kathleen M; Gulland, Frances M D; Conrad, Patricia A; Mazet, Jonna A K; Johnson, Christine K

2015-04-01

The coccidian parasite Toxoplasma gondii infects humans and warm-blooded animals worldwide. The ecology of this parasite in marine systems is poorly understood, although many marine mammals are infected and susceptible to clinical toxoplasmosis. We summarized the lesions associated with T. gondii infection in the California sea lion (Zalophus californianus) population and investigated the prevalence of and risk factors associated with T. gondii exposure, as indicated by antibody. Five confirmed and four suspected cases of T. gondii infection were identified by analysis of 1,152 medical records of necropsied sea lions from 1975-2009. One suspected and two confirmed cases were identified in aborted fetuses from a sea lion rookery. Toxoplasmosis was the primary cause of death in five cases, including the two fetuses. Gross and histopathologic findings in T. gondii-infected sea lions were similar to those reported in other marine mammals. The most common lesions were encephalitis, meningitis, and myocarditis. The antibody prevalence in stranded, free-ranging sea lions for 1998-2009 was 2.5% (±0.03%; IgG titer 640). There was an increase in odds of exposure in sea lions with increasing age, suggesting cumulative risk of exposure and persistent antibody over time. The occurrence of disseminated T. gondii infection in aborted fetuses confirms vertical transmission in sea lions, and the increasing odds of exposure with age is consistent with additional opportunities for horizontal transmission in free-ranging sea lions over time. These data suggest that T. gondii may have two modes of transmission in the sea lion population. Overall, clinical disease was uncommon in our study which, along with low prevalence of T. gondii antibody, suggests substantially less-frequent exposure and lower susceptibility to clinical disease in California sea lions as compared to sympatric southern sea otters (Enhydra lutris nereis).

The role of domoic acid in abortion and premature parturition of California sea lions (Zalophus californianus) on San Miguel Island, California.

PubMed

Goldstein, Tracey; Zabka, Tanja S; Delong, Robert L; Wheeler, Elizabeth A; Ylitalo, Gina; Bargu, Sibel; Silver, Mary; Leighfield, Tod; Van Dolah, Frances; Langlois, Gregg; Sidor, Inga; Dunn, J Lawrence; Gulland, Frances M D

2009-01-01

Domoic acid is a glutaminergic neurotoxin produced by marine algae such as Pseudo-nitzschia australis. California sea lions (Zalophus californianus) ingest the toxin when foraging on planktivorous fish. Adult females comprise 60% of stranded animals admitted for rehabilitation due to acute domoic acid toxicosis and commonly suffer from reproductive failure, including abortions and premature live births. Domoic acid has been shown to cross the placenta exposing the fetus to the toxin. To determine whether domoic acid was playing a role in reproductive failure in sea lion rookeries, 67 aborted and live-born premature pups were sampled on San Miguel Island in 2005 and 2006 to investigate the causes for reproductive failure. Analyses included domoic acid, contaminant and infectious disease testing, and histologic examination. Pseudo-nitzschia spp. were present both in the environment and in sea lion feces, and domoic acid was detected in the sea lion feces and in 17% of pup samples tested. Histopathologic findings included systemic and localized inflammation and bacterial infections of amniotic origin, placental abruption, and brain edema. The primary lesion in five animals with measurable domoic acid concentrations was brain edema, a common finding and, in some cases, the only lesion observed in aborted premature pups born to domoic acid-intoxicated females in rehabilitation. Blubber organochlorine concentrations were lower than those measured previously in premature sea lion pups collected in the 1970s. While the etiology of abortion and premature parturition was varied in this study, these results suggest that domoic acid contributes to reproductive failure on California sea lion rookeries.

Clinical relevance of novel Otarine herpesvirus-3 in California sea lions (Zalophus californianus): lymphoma, esophageal ulcers, and strandings

PubMed Central

2012-01-01

Herpesviruses have been recognized in marine mammals, but their clinical relevance is not always easy to assess. A novel otarine herpesvirus-3 (OtHV3) was detected in a geriatric California sea lion (Zalophus californianus), and using a newly developed quantitative PCR assay paired with histology, OtHV3 was associated with esophageal ulcers and B cell lymphoblastic lymphoma in this animal. The prevalence and quantities of OtHV3 were then determined among buffy coats from 87 stranded and managed collection sea lions. Stranded sea lions had a higher prevalence of OtHV3 compared to managed collection sea lions (34.9% versus 12.5%; p = 0.04), and among the stranded sea lions, yearlings were most likely to be positive. Future epidemiological studies comparing the presence and viral loads of OtHV3 among a larger population of California sea lions with and without lymphoid neoplasia or esophageal ulcers would help elucidate the relevance of OtHV3-associated pathologies to these groups. PMID:23234600

Predictive Habitat Use of California Sea Lions and Its Implications for Fisheries Management

NASA Astrophysics Data System (ADS)

Briscoe, D.

2016-02-01

Advancements in satellite telemetry and remotely-sensed oceanography have shown that species and the environment they utilize are highly dynamic in space and time. However, biophysical features often overlap with human use. For this reason, spatially-explicit management approaches may only provide a snapshot of protection for a highly mobile species throughout its range. As a migratory species, California sea lions (Zalophus californianus) utilize dynamic oceanographic features that overlap with the California swordfish fishery, and are subject to incidental catch. The development of near-real time tools can assist in management efforts to mitigate against human impacts, such as fisheries interactions and dynamic marine species. Here, we combine near-real time remotely-sensed satellite oceanography, animal tracking data, and Generalized Additive Mixed Models (GAMMs) to: a) determine suitable habitat for 75 female California sea lions throughout their range, b) forecast when and where these non-target interactions are likely to occur, and c) validate these models with observed data of such interactions. Model results can be used to provide resource management that are highly responsive to the movement of managed species, ocean users, and underlying ocean features.

Predictive Habitat Use of California Sea Lions and Its Implications for Fisheries Management

NASA Astrophysics Data System (ADS)

Briscoe, D.

2016-12-01

Advancements in satellite telemetry and remotely-sensed oceanography have shown that species and the environment they utilize are highly dynamic in space and time. However, biophysical features often overlap with human use. For this reason, spatially-explicit management approaches may only provide a snapshot of protection for a highly mobile species throughout its range. As a migratory species, California sea lions (Zalophus californianus) utilize dynamic oceanographic features that overlap with the California swordfish fishery, and are subject to incidental catch. The development of near-real time tools can assist in management efforts to mitigate against human impacts, such as fisheries interactions and dynamic marine species. Here, we combine near-real time remotely-sensed satellite oceanography, animal tracking data, and Generalized Additive Mixed Models (GAMMs) to: a) determine suitable habitat for 75 female California sea lions throughout their range, b) forecast when and where these non-target interactions are likely to occur, and c) validate these models with observed data of such interactions. Model results can be used to provide resource management that are highly responsive to the movement of managed species, ocean users, and underlying ocean features.

p,p'-DDE bioaccumulation in female sea lions of the California Channel Islands

NASA Astrophysics Data System (ADS)

Connolly, John P.; Glaser, David

2002-05-01

An area of sediment on the Palos Verdes shelf and in Santa Monica Bay off Los Angeles, CA is contaminated with DDE and other breakdown products of DDT as a result of discharges of DDT through the Whites Point outfall. Elevated concentrations of DDE have been found in the water column of the Palos Verdes Shelf and in various fish species inhabiting the shelf and Santa Monica Bay. High concentrations have also been found in California sea lions from San Miguel Island and sea lion carcasses on Santa Catalina Island. These islands are located some distance from the Palos Verdes shelf and Santa Monica Bay. It was the purpose of this study to determine if it is likely that the Palos Verdes Shelf/Santa Monica Bay sediments were the principal source of the DDE in the Channel Island sea lions via a pathway from sediments to water and fish preyed on by sea lions. A time variable, age dependent, physiologically based toxicokinetic model of female California sea lions was developed. Mass and energy balance equations describe the uptake and loss of contaminants. The contaminants are partitioned among multiple body compartments, including lipid and non-lipid body tissue and milk. Contaminants are distributed into a fetus of females. Physiological and toxicokinetic data were used to establish rates of growth, respiration, reproduction and lactation, internal partitioning of DDE, efficiency of DDE uptake and rates of DDE excretion. The model was used to estimate the likely DDE exposure history of the sea lions in view of their DDE body burdens. Field-measured dietary composition and prey contaminant levels were then used to establish potential exposure to DDE from various regions within the Southern California Bight. Comparison of the estimated exposure history with that attainable from the various regions indicated that the more highly contaminated lactating females were exposed to prey at levels found only on the Palos Verdes Shelf and in Santa Monica Bay. Thus, it is likely

Predicting the impact of tsunami in California under rising sea level

NASA Astrophysics Data System (ADS)

Dura, T.; Garner, A. J.; Weiss, R.; Kopp, R. E.; Horton, B.

2017-12-01

The flood hazard for the California coast depends not only on the magnitude, location, and rupture length of Alaska-Aleutian subduction zone earthquakes and their resultant tsunamis, but also on rising sea levels, which combine with tsunamis to produce overall flood levels. The magnitude of future sea-level rise remains uncertain even on the decadal scale, with future sea-level projections becoming even more uncertain at timeframes of a century or more. Earthquake statistics indicate that timeframes of ten thousand to one hundred thousand years are needed to capture rare, very large earthquakes. Because of the different timescales between reliable sea-level projections and earthquake distributions, simply combining the different probabilities in the context of a tsunami hazard assessment may be flawed. Here, we considered 15 earthquakes between Mw 8 to Mw 9.4 bound by -171oW and -140oW of the Alaska-Aleutian subduction zone. We employed 24 realizations at each magnitude with random epicenter locations and different fault length-to-width ratios, and simulated the tsunami evolution from these 360 earthquakes at each decade from the years 2000 to 2200. These simulations were then carried out for different sea-level-rise projections to analyze the future flood hazard for California. Looking at the flood levels at tide gauges, we found that the flood level simulated at, for example, the year 2100 (including respective sea-level change) is different from the flood level calculated by adding the flood for the year 2000 to the sea-level change prediction for the year 2100. This is consistent for all sea-level rise scenarios, and this difference in flood levels range between 5% and 12% for the larger half of the given magnitude interval. Focusing on flood levels at the tide gauge in the Port of Los Angeles, the most probable flood level (including all earthquake magnitudes) in the year 2000 was 5 cm. Depending on the sea-level predictions, in the year 2050 the most probable

Dramatic increase in sea otter mortality from white sharks in California

USGS Publications Warehouse

Tinker, M. Tim; Hatfield, Brian B.; Harris, Michael D.; Ames, Jack A.

2016-01-01

Although southern sea otters (Enhydra lutris nereis) are not considered prey for white sharks (Carcharodon carcharias), sharks do nonetheless bite sea otters. We analyzed spatial and temporal trends in shark bites on sea otters in California, assessing the frequency of shark bite wounds in 1,870 carcasses collected since 1985. The proportion of stranded sea otters having shark bites has increased sharply since 2003, and white shark bites now account for >50% of recovered carcasses. The trend was most pronounced in the southern part of the range, from Estero Bay to Point Conception, where shark bite frequency has increased eightfold. Seasonal trends were also evident: most shark-bitten carcasses are recovered in late summer and fall; however, the period of elevated shark bite frequency has lengthened. The causes of these trends are unclear, but possible contributing factors include increased white shark abundance and/or changes in white shark behavior and distribution. In particular, the spatiotemporal patterns of shark-bitten sea otters match increases in pinniped populations, and the increased availability of marine mammal prey for white sharks may have led to more sharks spending more time in nearshore waters utilized by both sea otters and pinnipeds.

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Southwest) California Sea Mussel and Bay Mussel

DTIC Science & Technology

1988-09-01

FishesS and Invertebrates (Pacific Southwest) CALIFORNIA SEA MUSSEL AND BAY MUSSEL Cn Coastal Ecology Group *Fish and Wildlife Service Waterways...September 1988 Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Southwest) CALIFORNIA SEA MUSSEL...AND BAY MUSSEL by William N. Shaw Fred Telonicher Marine Laboratory Humboldt State University Trinidad, CA 95570 Thomas J. Hassler U.S. Fish anu

Earth Observation taken by the STS-125 Crew

NASA Image and Video Library

2009-05-13

S125-E-007099 (13 May 2009) --- Part of southern California, including the San Diego area, and the border with Mexico can be seen in this STS-125 still photo taken from the Space Shuttle Atlantis as it passed over the Pacific Coast. The Salton Sea can be seen at upper right. The greater Los Angeles area is just out of frame at upper left.

Earth observations during STS-73

NASA Image and Video Library

1993-10-20

STS058-74-000R (18 Oct-1 Nov 1993) --- A broad view westward along the Colorado River from just below Glen Canyon Dam (out of picture), through the entire Grand Canyon to Lake Mead and Las Vegas, and westward to include southern Nevada and much of California. The Salton Sea, Los Angeles Basin, and Great Valley rim the Pacific Coast in the distance. Photo credit: NASA

Personality dimensions of the captive California sea lion (Zalophus californianus).

PubMed

Ciardelli, Lillian E; Weiss, Alexander; Powell, David M; Reiss, Diana

2017-02-01

Although the field of animal personality research is growing, information on sea lion personality is lacking. This is surprising as sea lions are charismatic, cognitively advanced, and relatively accessible for research. In addition, their presence in captivity and frequent interactions with humans allow for them to be closely observed in various contexts. These interactions provide a valuable and unique opportunity to assess dimensions of their personality. This study created a personality survey for captive California sea lions (Zalophus californianus) using a 3-step approach that balances comprehensiveness and comparability to other species. Zookeepers (N = 43) at 5 zoological parks rated sea lions (N = 16) on 52 personality traits and 7 training traits. A principal components analysis and regularized exploratory factor analysis revealed 3 dimensions (Extraversion/Impulsivity, Dominance/Confidence, and Reactivity/Undependability). Each dimension was significantly correlated with at least 1 training trait. Pups and juveniles scored significantly higher on Extraversion/Impulsivity than adults. No other age or sex effects were present on this or any other dimension. Sea lions are cognitively complex marine mammals that represent a valuable addition to the group of species in which personality structure and function have been studied. The unique behavioral and ecological characteristics of sea lions offer another vantage point for understanding how personality varies between disparate species. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Water Transfers, Air Quality, Ecosystems and Population Growth at the US-Mexico Border: An Integrated Model of the Mexicali and Imperial Valleys

NASA Astrophysics Data System (ADS)

Forster, C. B.; Gonzalez, T.; Peach, J.; Kjelland, M.; Collins, K.; Grant, W. E.

2006-12-01

Borderland communities in the Imperial-Mexicali Valleys (IMVs) of California (U.S.A.) and Mexicali (Mexico) are experiencing socioeconomic and environmental changes driven by policy makers and environmental conditions both within and outside the IMVs. The Colorado River Quantification Settlement Agreement (QSA) of 2003 will transfer 30 million acre-feet of Colorado River water from Imperial Valley (IV) agricultural users to Southern California urban users over a 75-year period. Because the water level of the Salton Sea is supported by agricultural runoff, reduced water flows to the sea raise concerns that: 1) air quality will be degraded as dust is generated by the drying Sea-bed, and 2) declining fish populations due to increasing salinity will no longer support birds migrating along a key avian flyway. Rapid population growth in the Mexican border-city of Mexicali, combined with new power plants and plans for water reuse, raises concerns that: 1) the quantity and quality of water supplied to the Salton Sea will decline, and 2) increased vehicle use and electrical power generation will lead to declining air quality in the binational air basin. Each concern may be affected by climate change. As environmental factors change, so too may the agricultural economy of the Imperial Valley that, in turn, depends on the availability of both water and manual labor. The economy of Mexicali is dominated by the maquiladora (manufacturing) industry that depends upon the availability of power, labor and water. A system dynamics model, with annual time step, simulates this complex binational system. The model was developed by an academic team with input from local experts/decision-makers from both Mexico and the US. We are preparing to engage community stakeholders and decision-makers in exploring the model. Insights gained from model results yield better understanding of the consequences of alternative future scenarios that include: QSA water transfers and land fallowing plans

Persistent organic pollutants in the blood of free-ranging sea otters (Enhydra lutris ssp.) in Alaska and California

USGS Publications Warehouse

Jessup, David A.; Johnson, Christine K.; Estes, James A.; Carlson-Bremer, Daphne; Jarman, Walter M.; Reese, Stacey; Dodd, Erin; Tinker, M. Tim; Ziccardi, Michael H.

2010-01-01

As part of tagging and ecologic research efforts in 1997 and 1998, apparently healthy sea otters of four age-sex classes in six locations in Alaska and three in California were sampled for persistent organic pollutants (POPs) and other chemicals of ecologic or environmental concern (COECs). Published techniques for the detection of POPs (specifically Σpolychlorinated biphenyls [PCBs], ΣDDTs, Σhexachlorocyclohexanes [HCHs], Σpolycyclic aromatic hydrocarbons [PAHs], Σchlordanes [CHLs], hexachlorobenzene [HCB], dieldrin, and mirex) in the tissue of dead otters were modified for use with serum from live sea otters. Toxic equivalencies (TEQs) were calculated for POPs with proven bioactivity. Strong location effects were seen for most POPs and COECs; sea otters in California generally showed higher mean concentrations than those in Alaska. Differences in contaminant concentrations were detected among age and sex classes, with high levels frequently observed in subadults. Very high levels of ΣDDT were detected in male sea otters in Elkhorn Slough, California, where strong freshwater outflow from agricultural areas occurs seasonally. All contaminants except mirex differed among Alaskan locations; only ΣDDT, HCB, and chlorpyrifos differed within California. High levels of ΣPCB (particularly larger, more persistent congeners) were detected at two locations in Alaska where associations between elevated PCBs and military activity have been established, while higher PCB levels were found at all three locations in California where no point source of PCBs has been identified. Although POP and COEC concentrations in blood may be less likely to reflect total body burden, concentrations in blood of healthy animals may be more biologically relevant and less influenced by state of nutrition or perimortem factors than other tissues routinely sampled.

Pathology of domoic acid toxicity in California sea lions (Zalophus californianus).

PubMed

Silvagni, P A; Lowenstine, L J; Spraker, T; Lipscomb, T P; Gulland, F M D

2005-03-01

Over 100 free-ranging adult California sea lions (Zalophus californianus) and one Northern fur seal (Callorhinus ursinus), predominantly adult females, were intoxicated by domoic acid (DA) during three harmful algal blooms between 1998 and 2000 in central and northern California coastal waters. The vector prey item was Northern anchovy (Engraulis mordax) and the primary DA-producing algal diatom was Psuedonitzschia australis. Postmortem examination revealed gross and histologic findings that were distinctive and aided in diagnosis. A total of 109 sea lions were examined, dying between 1 day and 10 months after admission to a marine mammal rehabilitation center. Persistent seizures with obtundation were the main clinical findings. Frequent gross findings in animals dying acutely consisted of piriform lobe malacia, myocardial pallor, bronchopneumonia, and complications related to pregnancy. Gross findings in animals dying months after intoxication included bilateral hippocampal atrophy. Histologic observations implicated limbic system seizure injury consistent with excitotoxin exposure. Peracutely, there was microvesicular hydropic degeneration within the neuropil of the hippocampus, amygdala, pyriform lobe, and other limbic structures. Acutely, there was ischemic neuronal necrosis, particularly apparent in the granular cells of the dentate gyrus and the pyramidal cells within the hippocampus cornu ammonis (CA) sectors CA4, CA3, and CA1. Dentate granular cell necrosis has not been reported in human or experimental animal DA toxicity and may be unique to sea lions. Chronically, there was gliosis, mild nonsuppurative inflammation, and loss of laminar organization in affected areas.

Cyclical changes in seroprevalence of leptospirosis in California sea lions: endemic and epidemic disease in one host species?

PubMed Central

Lloyd-Smith, James O; Greig, Denise J; Hietala, Sharon; Ghneim, George S; Palmer, Lauren; St Leger, Judy; Grenfell, Bryan T; Gulland, Frances MD

2007-01-01

Background Leptospirosis is a zoonotic disease infecting a broad range of mammalian hosts, and is re-emerging globally. California sea lions (Zalophus californianus) have experienced recurrent outbreaks of leptospirosis since 1970, but it is unknown whether the pathogen persists in the sea lion population or is introduced repeatedly from external reservoirs. Methods We analyzed serum samples collected over an 11-year period from 1344 California sea lions that stranded alive on the California coast, using the microscopic agglutination test (MAT) for antibodies to Leptospira interrogans serovar Pomona. We evaluated seroprevalence among yearlings as a measure of incidence in the population, and characterized antibody persistence times based on temporal changes in the distribution of titer scores. We conducted multinomial logistic regression to determine individual risk factors for seropositivity with high and low titers. Results The serosurvey revealed cyclical patterns in seroprevalence to L. interrogans serovar Pomona, with 4–5 year periodicity and peak seroprevalence above 50%. Seroprevalence in yearling sea lions was an accurate index of exposure among all age classses, and indicated on-going exposure to leptospires in non-outbreak years. Analysis of titer decay rates showed that some individuals probably maintain high titers for more than a year following exposure. Conclusion This study presents results of an unprecedented long-term serosurveillance program in marine mammals. Our results suggest that leptospirosis is endemic in California sea lions, but also causes periodic epidemics of acute disease. The findings call into question the classical dichotomy between maintenance hosts of leptospirosis, which experience chronic but largely asymptomatic infections, and accidental hosts, which suffer acute illness or death as a result of disease spillover from reservoir species. PMID:17986335

Effects of Age, Colony, and Sex on Mercury Concentrations in California Sea Lions.

PubMed

McHuron, Elizabeth A; Peterson, Sarah H; Ackerman, Joshua T; Melin, Sharon R; Harris, Jeffrey D; Costa, Daniel P

2016-01-01

We measured total mercury (THg) concentrations in California sea lions (Zalophus californianus) and examined how concentrations varied with age class, colony, and sex. Because Hg exposure is primarily via diet, we used nitrogen (δ (15)N) and carbon (δ (13)C) stable isotopes to determine if intraspecific differences in THg concentrations could be explained by feeding ecology. Blood and hair were collected from 21 adult females and 57 juveniles from three colonies in central and southern California (San Nicolas, San Miguel, and Año Nuevo Islands). Total Hg concentrations ranged from 0.01 to 0.31 μg g(-1) wet weight (ww) in blood and 0.74 to 21.00 μg g(-1) dry weight (dw) in hair. Adult females had greater mean THg concentrations than juveniles in blood (0.15 vs. 0.03 μg(-1) ww) and hair (10.10 vs. 3.25 μg(-1) dw). Age class differences in THg concentrations did not appear to be driven by trophic level or habitat type because there were no differences in δ (15)N or δ (13)C values between adults and juveniles. Total Hg concentrations in adult females were 54 % (blood) and 24 % (hair) greater in females from San Miguel than females from San Nicolas Island, which may have been because sea lions from the two islands foraged in different areas. For juveniles, we detected some differences in THg concentrations with colony and sex, although these were likely due to sampling effects and not ecological differences. Overall, THg concentrations in California sea lions were within the range documented for other marine mammals and were generally below toxicity benchmarks for fish-eating wildlife.

Maximum Magnitude and Probabilities of Induced Earthquakes in California Geothermal Fields: Applications for a Science-Based Decision Framework

NASA Astrophysics Data System (ADS)

Weiser, Deborah Anne

Induced seismicity is occurring at increasing rates around the country. Brodsky and Lajoie (2013) and others have recognized anthropogenic quakes at a few geothermal fields in California. I use three techniques to assess if there are induced earthquakes in California geothermal fields; there are three sites with clear induced seismicity: Brawley, The Geysers, and Salton Sea. Moderate to strong evidence is found at Casa Diablo, Coso, East Mesa, and Susanville. Little to no evidence is found for Heber and Wendel. I develop a set of tools to reduce or cope with the risk imposed by these earthquakes, and also to address uncertainties through simulations. I test if an earthquake catalog may be bounded by an upper magnitude limit. I address whether the earthquake record during pumping time is consistent with the past earthquake record, or if injection can explain all or some of the earthquakes. I also present ways to assess the probability of future earthquake occurrence based on past records. I summarize current legislation for eight states where induced earthquakes are of concern. Unlike tectonic earthquakes, the hazard from induced earthquakes has the potential to be modified. I discuss direct and indirect mitigation practices. I present a framework with scientific and communication techniques for assessing uncertainty, ultimately allowing more informed decisions to be made.

Sea-level rise and refuge habitats for tidal marsh species: can artificial islands save the California Ridgway's rail?

USGS Publications Warehouse

Overton, Cory T.; Takekawa, John Y.; Casazza, Michael L.; Bui, Thuy-Vy D.; Holyoak, Marcel; Strong, Donald R.

2014-01-01

Terrestrial species living in intertidal habitats experience refuge limitation during periods of tidal inundation, which may be exacerbated by seasonal variation in vegetation structure, tidal cycles, and land-use change. Sea-level rise projections indicate the severity of refuge limitation may increase. Artificial habitats that provide escape cover during tidal inundation have been proposed as a temporary solution to alleviate these limitations. We tested for evidence of refuge habitat limitation in a population of endangered California Ridgway's rail (Rallus obsoletus obsoletus; hereafter California rail) through use of artificial floating island habitats provided during two winters. Previous studies demonstrated that California rail mortality was especially high during the winter and periods of increased tidal inundation, suggesting that tidal refuge habitat is critical to survival. In our study, California rail regularly used artificial islands during higher tides and daylight hours. When tide levels inundated the marsh plain, use of artificial islands was at least 300 times more frequent than would be expected if California rails used artificial habitats proportional to their availability (0.016%). Probability of use varied among islands, and low levels of use were observed at night. These patterns may result from anti-predator behaviors and heterogeneity in either rail density or availability of natural refuges. Endemic saltmarsh species are increasingly at risk from habitat change resulting from sea-level rise and development of adjacent uplands. Escape cover during tidal inundation may need to be supplemented if species are to survive. Artificial habitats may provide effective short-term mitigation for habitat change and sea-level rise in tidal marsh environments, particularly for conservation-reliant species such as California rails.

Metastrongyloid nematode (Otostrongylus circumlitus) infection in a stranded California sea lion (Zalophus californianus)--a new host-parasite association.

PubMed

Kelly, Terra R; Greig, Denise; Colegrove, Kathleen M; Lowenstine, Linda J; Dailey, Murray; Gulland, Frances M; Haulena, Martin

2005-07-01

A stranded yearling male California sea lion was admitted to a rehabilitation center June 2003. On presentation, the sea lion was emaciated and had diarrhea and neutrophilia. Two weeks later, the animal became anorexic, blood and mucus were observed around the oral cavity, and corneal opacity was noted in the right eye. Hematology results at that time included leukocytosis consisting of neutrophilia with a left shift, anemia, and thrombocytopenia. Despite supportive care, the sea lion died. On post mortem examination, there were multiple areas of hemorrhage scattered throughout all lung lobes, and pulmonary blood vessels were occluded by fibrin thrombi. Nematodes identified as immature forms of Otostrongylus circumlitus were found in the right ventricle and pulmonary arteries. Histologic findings in the lungs included severe suppurative and necrotizing arteritis with vascular thrombosis, interstitial pneumonia, and large areas of pulmonary hemorrhage. This report of O. circumlitus infection in a California sea lion (Zalophus californianus) might indicate a potentially new host-parasite association.

A kinematic model for the late Cenozoic development of southern California crust and upper mantle

NASA Technical Reports Server (NTRS)

Humphreys, Eugene D.; Hager, Bradford H.

1990-01-01

A model is developed for the young and ongoing kinematic deformation of the southern California crust and upper mantle. The kinematic model qualitatively explains both the overall seismic structure of the upper mantle and much of the known geological history of the late Cenozoic as consequences of ongoing convection beneath southern California. In this model, the high-velocity upper-mantle anomaly of the Transverse ranges is created through the convergence and sinking of the entire thickness of subcrustal lihtosphere, and the low-velocity upper-mantle anomaly beneath the Salton Trough region is attributed to high temperatures and 1-4 percent partial melt related to adiabatic decompression during mantle upwelling.

Use of laser rhinoscopy to treat a nasal obstruction in a captive California sea lion (Zalophus californianus).

PubMed

Sherrill, Johanna; Peavy, George M; Kopit, Mark J; Garner, Michael M; Gardiner, Chris H; Adams, Lance M

2004-06-01

Laser rhinoscopy was used to treat a nasal obstruction in a captive California sea lion (Zalophus californianus). The rehabilitated, adult, female sea lion developed mucopurulent, intermittent, bilateral nasal discharge and functional nasal obstruction 20 mo after acquisition by the Aquarium of the Pacific in Long Beach, California. A 3-mm-thick soft tissue structure spanning the region between the soft and hard palates, a deviated nasal septum, and several nasopharyngeal polyps were identified. Biopsies and cultures of the obstructive web showed ulcerative granulation tissue with suppurative inflammation, bacterial infection, and a partial section of an arthropod larva (not speciated). Laser rhinoscopy was performed to relieve the caudal nasopharyngeal obstruction and ablate the polyps. The sea lion appeared to breathe through the nares with lessened nasal discharge for a period of 6 wk after laser therapy, but within 8 wk the mucopurulent nasal discharge returned, the obstruction had reformed, and the sea lion was euthanized. Postmortem examination confirmed antemortem diagnoses of caudal nasopharyngeal obstruction secondary to inflammatory tissue; however, no additional sections of arthropod parasites were located microscopically.

Deep-Diving California Sea Lions: Are they Pushing their Physiological Limit

DTIC Science & Technology

2013-09-30

backpack digital recorders to measure blood oxygen depletion, heart rate, and flipper stroke rate in dives of California sea lions during maternal...relationship between changes in heart rate to blood O2 profiles, and 3) documentation of flipper stroke rate profiles during shallow and deep dives, and...assessment of the relationship of stroke rate to both changes in heart rate and changes in blood O2 profiles. APPROACH Objective 1: In order to

Mortality of sea lions along the central California coast linked to a toxic diatom bloom.

PubMed

Scholin, C A; Gulland, F; Doucette, G J; Benson, S; Busman, M; Chavez, F P; Cordaro, J; DeLong, R; De Vogelaere, A; Harvey, J; Haulena, M; Lefebvre, K; Lipscomb, T; Loscutoff, S; Lowenstine, L J; Marin, R; Miller, P E; McLellan, W A; Moeller, P D; Powell, C L; Rowles, T; Silvagni, P; Silver, M; Spraker, T; Trainer, V; Van Dolah, F M

2000-01-06

Over 400 California sea lions (Zalophus californianus) died and many others displayed signs of neurological dysfunction along the central California coast during May and June 1998. A bloom of Pseudo-nitzschia australis (diatom) was observed in the Monterey Bay region during the same period. This bloom was associated with production of domoic acid (DA), a neurotoxin that was also detected in planktivorous fish, including the northern anchovy (Engraulis mordax), and in sea lion body fluids. These and other concurrent observations demonstrate the trophic transfer of DA resulting in marine mammal mortality. In contrast to fish, blue mussels (Mytilus edulus) collected during the DA outbreak contained no DA or only trace amounts. Such findings reveal that monitoring of mussel toxicity alone does not necessarily provide adequate warning of DA entering the food web at levels sufficient to harm marine wildlife and perhaps humans.

Contamination status and accumulation profiles of organotins in sea otters (Enhydra lutris) found dead along the coasts of California, Washington, Alaska (USA), and Kamchatka (Russia)

USGS Publications Warehouse

Murata, S.; Takahashi, S.; Agusa, T.; Thomas, N.J.; Kannan, K.; Tanabe, S.

2008-01-01

Organotin compounds (OTs) including mono- to tri-butyltins, -phenyltins, and -octyltins were determined in the liver of adult sea otters (Enhydra lutris) found dead along the coasts of California, Washington, and Alaska in the USA and Kamchatka, Russia. Total concentrations of OTs in sea otters from California ranged from 34 to 4100 ng/g on a wet weight basis. The order of concentrations of OTs in sea otters was total butyltins ??? total octyltins ??? total phenyltins. Elevated concentrations of butyltins (BTs) were found in some otters classified under 'infectious-disease' mortality category. Concentrations of BTs in few of these otters were close to or above the threshold levels for adverse health effects. Total butyltin concentrations decreased significantly in the livers of California sea otters since the 1990s. Based on the concentrations of organotins in sea otters collected from 1992 to 2002, the half-lives of tributyltin and total butyltins in sea otters were estimated to be approximately three years. ?? 2008 Elsevier Ltd. All rights reserved.

Crustal Spreading in Southern California: The Imperial Valley and the Gulf of California formed by the rifting apart of a continental plate.

PubMed

Elders, W A; Rex, R W; Robinson, P T; Biehler, S; Meidav, T

1972-10-06

The current excitement among geologists and geophysicists stemming from the "new global tectonics" has led to a widespread, speculative reinterpretation of continental geology. The Gulf of California and its continuation into the Imperial Valley provide an excellent opportunity for studying the border zone between the North American and Pacific plates, and an interface of continental and oceanic tectonics. The Salton trough, the landward extension of the gulf, is a broad structural depression, comparable in size with the deeper marine basins of the southern part of the gulf, but here partially filled with sediments deposited by the Colorado River.

Effects of age, colony, and sex on mercury concentrations in California sea lions

USGS Publications Warehouse

McHuron, Elizibeth A; Peterson, Sarah H.; Ackerman, Joshua T.; Melin, Sharon R.; Harris, Jeffrey D.; Costa, Daniel P.

2016-01-01

We measured total mercury (THg) concentrations in California sea lions (Zalophus californianus) and examined how concentrations varied with age class, colony, and sex. Because Hg exposure is primarily via diet, we used nitrogen (δ 15N) and carbon (δ 13C) stable isotopes to determine if intraspecific differences in THg concentrations could be explained by feeding ecology. Blood and hair were collected from 21 adult females and 57 juveniles from three colonies in central and southern California (San Nicolas, San Miguel, and Año Nuevo Islands). Total Hg concentrations ranged from 0.01 to 0.31 μg g−1 wet weight (ww) in blood and 0.74 to 21.00 μg g−1 dry weight (dw) in hair. Adult females had greater mean THg concentrations than juveniles in blood (0.15 vs. 0.03 μg−1 ww) and hair (10.10 vs. 3.25 μg−1 dw). Age class differences in THg concentrations did not appear to be driven by trophic level or habitat type because there were no differences in δ 15N or δ 13C values between adults and juveniles. Total Hg concentrations in adult females were 54 % (blood) and 24 % (hair) greater in females from San Miguel than females from San Nicolas Island, which may have been because sea lions from the two islands foraged in different areas. For juveniles, we detected some differences in THg concentrations with colony and sex, although these were likely due to sampling effects and not ecological differences. Overall, THg concentrations in California sea lions were within the range documented for other marine mammals and were generally below toxicity benchmarks for fish-eating wildlife.

Common cancer in a wild animal: the California sea lion (Zalophus californianus) as an emerging model for carcinogenesis

PubMed Central

Browning, Helen M.; Gulland, Frances M. D.; Hammond, John A.; Colegrove, Kathleen M.; Hall, Ailsa J.

2015-01-01

Naturally occurring cancers in non-laboratory species have great potential in helping to decipher the often complex causes of neoplasia. Wild animal models could add substantially to our understanding of carcinogenesis, particularly of genetic and environmental interactions, but they are currently underutilized. Studying neoplasia in wild animals is difficult and especially challenging in marine mammals owing to their inaccessibility, lack of exposure history, and ethical, logistical and legal limits on experimentation. Despite this, California sea lions (Zalophus californianus) offer an opportunity to investigate risk factors for neoplasia development that have implications for terrestrial mammals and humans who share much of their environment and diet. A relatively accessible California sea lion population on the west coast of the USA has a high prevalence of urogenital carcinoma and is regularly sampled during veterinary care in wildlife rehabilitation centres. Collaborative studies have revealed that genotype, persistent organic pollutants and a herpesvirus are all associated with this cancer. This paper reviews research to date on the epidemiology and pathogenesis of urogenital carcinoma in this species, and presents the California sea lion as an important and currently underexploited wild animal model of carcinogenesis. PMID:26056370

Integrated Modeling of Water Policy Futures in the Imperial-Mexicali Valleys

NASA Astrophysics Data System (ADS)

Kjelland, M. K.; Forster, C. B.; Grant, W. E.; Collins, K.

2004-12-01

Divided by an international border, the Imperial-Mexicali Valleys (IMVs) are linked by shared history, natural resources, culture and economy. This region is experiencing changes driven by policy makers both within and outside the IMVs. The largest external decision, the Colorado River Quantification Settlement Agreement (QSA) of 2003, opens the door to a laboratory for studying the consequences of a massive transfer of agricultural water to municipal users. Two irrigation districts, two urban water agencies and the State of California have agreed to a 75 year of more than 30 million acre-feet of Colorado River water from agricultural to urban use. Although Imperial Valley farmers will be compensated for water conservation and land fallowing, the economic, environmental and social consequences are unclear. Farmers who fallow will likely cause a greater impact on local businesses and government than those choosing on-field water conservation. Reduced agricultural water use causes reduced flow of irrigation runoff, at higher salinity than before, to the Salton Sea that, in turn, impacts the population dynamics of Ichthyan and Avian species at the Salton Sea. Municipal wastewater discharged into the New River by Mexicali, Mexico is also an important source of inflow to the Salton Sea that will be reduce by plans to reclaim the wastewater for various uses, including cooling water for two new power plants in the Mexicali. A restoration program is funded to produce a Sea with much reduced surface area. But this approach may, in turn, lead to increases in windblown dust from the dry lakebed that will contribute to an air basin already designated as a federal nonattainment area for particulate emissions. Additional water will be conserved by lining the All American and Coachella canals. But, eliminating seepage from the All American canal reduces groundwater recharge to aquifers used by Mexican farmers. A complex interplay of water-related issues must be accounted for if

Asymptomatic and chronic carriage of Leptospira interrogans serovar Pomona in California sea lions (Zalophus californianus)

USDA-ARS?s Scientific Manuscript database

Since 1970, periodic outbreaks of leptospirosis, caused by pathogenic spirochetes in the genus Leptospira, have caused morbidity and mortality of California sea lions (Zalophus californianus) along the Pacific coast of North America. Yearly seasonal epizootics of varying magnitude occur between the ...

California sea otter (Enhydra lutris nereis) census results, Spring 2016

USGS Publications Warehouse

Tinker, M. Tim; Hatfield, Brian B.

2016-09-19

The 2016 census of southern sea otters Enhydra lutris nereis was conducted in May along the mainland coast of central California and in April at San Nicolas Island in southern California. The 3-year average of combined counts from the mainland range and San Nicolas Island was 3,272. This is the first year that the official index has exceeded 3,090, the Endangered Species Act delisting threshold suggested by the U.S. Fish and Wildlife Service (the threshold would need to be exceeded for 3 consecutive years before delisting consideration). The 5-year average trend in abundance, including both the mainland range and San Nicolas Island populations, is positive at 3.2 percent per year; however, regional trends vary, with localized declines at the southern and northern peripheries of the mainland range. The lack of population growth in the range peripheries over recent years likely explains the cessation of range expansion, with the range limits remaining almost unchanged from the previous 5 years.

In Utero Domoic Acid Toxicity: A Fetal Basis to Adult Disease in the California Sea Lion (Zalophus californianus)

PubMed Central

Ramsdell, John S.; Zabka, Tanja S.

2008-01-01

California sea lions have been a repeated subject of investigation for early life toxicity, which has been documented to occur with increasing frequency from late February through mid-May in association with organochlorine (PCB and DDT) poisoning and infectious disease in the 1970’s and domoic acid poisoning in the last decade. The mass early life mortality events result from the concentrated breeding grounds and synchronization of reproduction over a 28 day post partum estrus cycle and 11 month in utero phase. This physiological synchronization is triggered by a decreasing photoperiod of 11.48 h/day that occurs approximately 90 days after conception at the major California breeding grounds. The photoperiod trigger activates implantation of embryos to proceed with development for the next 242 days until birth. Embryonic diapause is a selectable trait thought to optimize timing for food utilization and male migratory patterns; yet from the toxicological perspective presented here also serves to synchronize developmental toxicity of pulsed environmental events such as domoic acid poisoning. Research studies in laboratory animals have defined age-dependent neurotoxic effects during development and windows of susceptibility to domoic acid exposure. This review will evaluate experimental domoic acid neurotoxicity in developing rodents and, aided by comparative allometric projections, will analyze potential prenatal toxicity and exposure susceptibility in the California sea lion. This analysis should provide a useful tool to forecast fetal toxicity and understand the impact of fetal toxicity on adult disease of the California sea lion. PMID:18728728

Hippocampal neuropathology of domoic acid-induced epilepsy in California sea lions (Zalophus californianus)

PubMed Central

Buckmaster, Paul S.; Wen, Xiling; Toyoda, Izumi; Gulland, Frances M. D.; Van Bonn, William

2014-01-01

California sea lions (Zalophus californianus) are abundant human-sized carnivores with large gyrencephalic brains. They develop epilepsy after experiencing status epilepticus when naturally exposed to domoic acid. We tested whether sea lions previously exposed to DA (chronic DA sea lions) display hippocampal neuropathology similar to that of human patients with temporal lobe epilepsy. Hippocampi were obtained from control and chronic DA sea lions. Stereology was used to estimate numbers of Nissl-stained neurons per hippocampus in the granule cell layer, hilus, and the pyramidal cell layer of CA3, CA2, and CA1 subfields. Adjacent sections were processed for somatostatin-immunoreactivity or Timm-stained, and the extent of mossy fiber sprouting was measured stereologically. Chronic DA sea lions displayed hippocampal neuron loss in patterns and extents similar but not identical to those reported previously for human patients with temporal lobe epilepsy. Similar to human patients, hippocampal sclerosis in sea lions was unilateral in 79% of cases, mossy fiber sprouting was a common neuropathological abnormality, and somatostatin-immunoreactive axons were exuberant in the dentate gyrus despite loss of immunopositive hilar neurons. Thus, hippocampal neuropathology of chronic DA sea lions is similar to that of human patients with temporal lobe epilepsy. PMID:24638960

Hippocampal neuropathology of domoic acid-induced epilepsy in California sea lions (Zalophus californianus).

PubMed

Buckmaster, Paul S; Wen, Xiling; Toyoda, Izumi; Gulland, Frances M D; Van Bonn, William

2014-05-01

California sea lions (Zalophus californianus) are abundant human-sized carnivores with large gyrencephalic brains. They develop epilepsy after experiencing status epilepticus when naturally exposed to domoic acid. We tested whether sea lions previously exposed to DA (chronic DA sea lions) display hippocampal neuropathology similar to that of human patients with temporal lobe epilepsy. Hippocampi were obtained from control and chronic DA sea lions. Stereology was used to estimate numbers of Nissl-stained neurons per hippocampus in the granule cell layer, hilus, and pyramidal cell layer of CA3, CA2, and CA1 subfields. Adjacent sections were processed for somatostatin immunoreactivity or Timm-stained, and the extent of mossy fiber sprouting was measured stereologically. Chronic DA sea lions displayed hippocampal neuron loss in patterns and extents similar but not identical to those reported previously for human patients with temporal lobe epilepsy. Similar to human patients, hippocampal sclerosis in sea lions was unilateral in 79% of cases, mossy fiber sprouting was a common neuropathological abnormality, and somatostatin-immunoreactive axons were exuberant in the dentate gyrus despite loss of immunopositive hilar neurons. Thus, hippocampal neuropathology of chronic DA sea lions is similar to that of human patients with temporal lobe epilepsy. Copyright © 2013 Wiley Periodicals, Inc.

The kinematics of the California sea lion foreflipper during forward swimming.

PubMed

Friedman, C; Leftwich, M C

2014-11-07

To determine the two-dimensional kinematics of the California sea lion foreflipper during thrust generation, a digital, high-definition video is obtained using a non-research female sea lion at the Smithsonian National Zoological Park in Washington, DC. The observational videos are used to extract maneuvers of interest--forward acceleration from rest using the foreflippers and banked turns. Single camera videos are analyzed to digitize the flipper during the motions using 10 points spanning root to tip in each frame. Digitized shapes were then fitted with an empirical function that quantitatively allows for both comparison between different claps, and for extracting kinematic data. The resulting function shows a high degree of curvature (with a camber of up to 32%). Analysis of sea lion acceleration from rest shows thrust production in the range of 150-680 N and maximum flipper angular velocity (for rotation about the shoulder joint) as high as 20 rad s⁻¹. Analysis of turning maneuvers indicate extreme agility and precision of movement driven by the foreflipper surfaces.

Common cancer in a wild animal: the California sea lion (Zalophus californianus) as an emerging model for carcinogenesis.

PubMed

Browning, Helen M; Gulland, Frances M D; Hammond, John A; Colegrove, Kathleen M; Hall, Ailsa J

2015-07-19

Naturally occurring cancers in non-laboratory species have great potential in helping to decipher the often complex causes of neoplasia. Wild animal models could add substantially to our understanding of carcinogenesis, particularly of genetic and environmental interactions, but they are currently underutilized. Studying neoplasia in wild animals is difficult and especially challenging in marine mammals owing to their inaccessibility, lack of exposure history, and ethical, logistical and legal limits on experimentation. Despite this, California sea lions (Zalophus californianus) offer an opportunity to investigate risk factors for neoplasia development that have implications for terrestrial mammals and humans who share much of their environment and diet. A relatively accessible California sea lion population on the west coast of the USA has a high prevalence of urogenital carcinoma and is regularly sampled during veterinary care in wildlife rehabilitation centres. Collaborative studies have revealed that genotype, persistent organic pollutants and a herpesvirus are all associated with this cancer. This paper reviews research to date on the epidemiology and pathogenesis of urogenital carcinoma in this species, and presents the California sea lion as an important and currently underexploited wild animal model of carcinogenesis. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Punctuated sediment discharge during early Pliocene birth of the Colorado River: Evidence from regional stratigraphy, sedimentology, and paleontology

USGS Publications Warehouse

Dorsey, Rebecca J.; O’Connell, Brennan; McDougall-Reid, Kristin; Homan, Mindy B.

2018-01-01

punctuated sediment discharge are assessed by comparing the depositional chronology to the record of global sea-level change. The lower Colorado River Valley and Salton Trough experienced marine transgression during a gradual fall in global sea level between ~ 6.3 and 5.5 Ma, implicating tectonic subsidence as the main driver of latest Miocene relative sea-level rise. A major fall of global sea level at 5.3 Ma outpaced subsidence and drove regional delta progradation, earliest flushing of Colorado River sand into the northern Gulf of California, and erosion of Bouse basal carbonate and siliciclastic members. The lower Colorado River valley was re-flooded by shallow marine waters during smaller changes in global sea level ~ 5.1–4.8 Ma, after the river first ran through it, which requires a mechanism to stop delivery of sand to the lower river valley. We propose that tectonically controlled subsidence along the lower Colorado River, upstream of the southern Bouse study area, temporarily trapped sediment and stopped delivery of sand to the lower river valley and northern Gulf of California for ~ 200–300 kyr. Massive progradation of the fluvial-deltaic system back down the river valley into the Salton Trough starting ~ 4.8–4.5 Ma apparently was driven by a huge increase in sediment discharge that overwhelmed the sediment-storage capacity of sub-basins along the lower river corridor and established the fully integrated river channel network.

Seismic imaging of the metamorphism of young sediment into new crystalline crust in the actively rifting Imperial Valley, California

USGS Publications Warehouse

Han, Liang; Hole, John; Stock, Joann; Fuis, Gary S.; Williams, Colin F.; Delph, Jonathan; Davenport, Kathy; Livers, Amanda

2016-01-01

Plate-boundary rifting between transform faults is opening the Imperial Valley of southern California and the rift is rapidly filling with sediment from the Colorado River. Three 65–90 km long seismic refraction profiles across and along the valley, acquired as part of the 2011 Salton Seismic Imaging Project, were analyzed to constrain upper crustal structure and the transition from sediment to underlying crystalline rock. Both first arrival travel-time tomography and frequency-domain full-waveform inversion were applied to provide P-wave velocity models down to ∼7 km depth. The valley margins are fault-bounded, beyond which thinner sediment has been deposited on preexisting crystalline rocks. Within the central basin, seismic velocity increases continuously from ∼1.8 km/s sediment at the surface to >6 km/s crystalline rock with no sharp discontinuity. Borehole data show young sediment is progressively metamorphosed into crystalline rock. The seismic velocity gradient with depth decreases approximately at the 4 km/s contour, which coincides with changes in the porosity and density gradient in borehole core samples. This change occurs at ∼3 km depth in most of the valley, but at only ∼1.5 km depth in the Salton Sea geothermal field. We interpret progressive metamorphism caused by high heat flow to be creating new crystalline crust throughout the valley at a rate comparable to the ≥2 km/Myr sedimentation rate. The newly formed crystalline crust extends to at least 7–8 km depth, and it is shallower and faster where heat flow is higher. Most of the active seismicity occurs within this new crust.

Seismic imaging of the metamorphism of young sediment into new crystalline crust in the actively rifting Imperial Valley, California

NASA Astrophysics Data System (ADS)

Han, Liang; Hole, John A.; Stock, Joann M.; Fuis, Gary S.; Williams, Colin F.; Delph, Jonathan R.; Davenport, Kathy K.; Livers, Amanda J.

2016-11-01

Plate-boundary rifting between transform faults is opening the Imperial Valley of southern California and the rift is rapidly filling with sediment from the Colorado River. Three 65-90 km long seismic refraction profiles across and along the valley, acquired as part of the 2011 Salton Seismic Imaging Project, were analyzed to constrain upper crustal structure and the transition from sediment to underlying crystalline rock. Both first arrival travel-time tomography and frequency-domain full-waveform inversion were applied to provide P-wave velocity models down to ˜7 km depth. The valley margins are fault-bounded, beyond which thinner sediment has been deposited on preexisting crystalline rocks. Within the central basin, seismic velocity increases continuously from ˜1.8 km/s sediment at the surface to >6 km/s crystalline rock with no sharp discontinuity. Borehole data show young sediment is progressively metamorphosed into crystalline rock. The seismic velocity gradient with depth decreases approximately at the 4 km/s contour, which coincides with changes in the porosity and density gradient in borehole core samples. This change occurs at ˜3 km depth in most of the valley, but at only ˜1.5 km depth in the Salton Sea geothermal field. We interpret progressive metamorphism caused by high heat flow to be creating new crystalline crust throughout the valley at a rate comparable to the ≥2 km/Myr sedimentation rate. The newly formed crystalline crust extends to at least 7-8 km depth, and it is shallower and faster where heat flow is higher. Most of the active seismicity occurs within this new crust.

Chapter 35: Productivity of marbled murrelets in California from observations of young at sea

Treesearch

C. John Ralph; Linda L. Long

1995-01-01

We designed and tested an intensive survey method in 1993 to identify juvenile Marbled Murrelets (Brachyramphus marmoratus) at sea. From this, we used the percent of juveniles seen in the sample as an index of productivity of murrelets along the California coast. We found 2.2 percent of the population sampled were juveniles, similar to our estimates...

THE DIATOM FLORA OF THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

NAKED AMOEBAE (PROTOZOA) OF THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

New records of the deep-sea anemone Phelliactis callicyclus Riemann-Zurneck, 1973 (Cnidaria, Actiniaria, Hormathiidae) from the Gulf of California, Mexico.

PubMed

Hendrickx, M E; Hinojosa-Corona, A; Ayón-Parente, M

2016-10-20

Specimens of a deep-sea anemone were observed in photographs and video footage taken with the Remotely Operated Vehicle JASON (WHOI Deep Submergence Laboratory) in the Gulf of California, Mexico, in May 2008. Comparison of our material with photographs and description of this species available in literature indicate that the sea anemones filmed during the JASON survey are most likely to represent Phelliactis callicyclus Riemann-Zurneck, 1973. This species has previously been reported from a locality in the Gulf of California near the present record. During the JASON survey, 28 specimens of P. callicyclus were spotted in 27 locations during six dives. The specimens occurred on angular rock outcrops along the escarpments of the transform faults of the Gulf of California, between depths of 993-2543 m and at temperatures ranging from 2.3 to 4.5°C. Based on these new records, Phelliactis callicyclus appears to be widely spread in the Gulf of California.

Forecasting sea cliff retreat in Southern California using process-based models and artificial neural networks

NASA Astrophysics Data System (ADS)

Limber, P. W.; Barnard, P.; Erikson, L. H.

2016-02-01

Modeling coastal geomorphic change over multi-decadal time and regional spatial scales (i.e. >20 km alongshore) is in high demand due to rising global sea levels and heavily populated coastal zones, but is challenging for several reasons: adequate geomorphic and oceanographic data often does not exist over the entire study area or time period; models can be too computationally expensive; and model uncertainty is high. In the absence of rich datasets and unlimited computer processing power, researchers are forced to leverage existing data, however sparse, and find analytical methods that minimize computation time without sacrificing (too much) model reliability. Machine learning techniques, such as artificial neural networks, can assimilate and efficiently extrapolate geomorphic model behavior over large areas. They can also facilitate ensemble model forecasts over a broad range of parameter space, which is useful when a paucity of observational data inhibits the constraint of model parameters. Here, we assimilate the behavior of two established process-based sea cliff erosion and retreat models into a neural network to forecast the impacts of sea level rise on sea cliff retreat in Southern California ( 400 km) through the 21st century. Using inputs such as historical cliff retreat rates, mean wave power, and whether or not a beach is present, the neural network independently reproduces modeled sea cliff retreat as a function of sea level rise with a high degree of confidence (R2 > 0.9, mean squared error < 0.1 m yr-1). Results will continuously improve as more model scenarios are assimilated into the neural network, and more field data (i.e., cliff composition and rock hardness) becomes available to tune the cliff retreat models. Preliminary results suggest that sea level rise rates of 2 to 20 mm yr-1 during the next century could accelerate historical cliff retreat rates in Southern California by an average of 0.10 - 0.56 m yr-1.

Investigations of peritoneal and intestinal infections of adult hookworms (Uncinaria spp.) in northern fur seal (Callorhinus ursinus) and California sea lion (Zalophus californianus) pups on San Miguel Island, California (2003).

PubMed

Lyons, Eugene T; Delong, R L; Nadler, S A; Laake, J L; Orr, A J; Delong, B L; Pagan, C

2011-09-01

The peritoneal cavity (PNC) and intestine of northern fur seal (Callorhinus ursinus) pups and California sea lion (Zalophus californianus) pups that died in late July and early August, 2003, on San Miguel Island, California, were examined for hookworms. Prevalence and morphometric studies were done with the hookworms in addition to molecular characterization. Based on this and previous molecular studies, hookworms from fur seals are designated as Uncinaria lucasi and the species from sea lions as Uncinaria species A. Adult hookworms were found in the PNC of 35 of 57 (61.4%) fur seal pups and of 13 of 104 (12.5%) sea lion pups. The number of hookworms located in the PNC ranged from 1 to 33 (median = 3) for the infected fur seal pups and 1 to 16 (median = 2) for the infected sea lion pups. In addition to the PNC, intestines of 43 fur seal and 32 sea lion pups were examined. All of these pups were positive for adult hookworms. The worms were counted from all but one of the sea lion pups. Numbers of these parasites in the intestine varied from 3 to 2,344 (median = 931) for the fur seal pups and 39 to 2,766 (median = 643) for the sea lion pups. Sea lion pups with peritoneal infections had higher intensity infections in the intestines than did pups without peritoneal infections, lending some support for the hypothesis that peritoneal infections result from high-intensity infections of adult worms. There was no difference in intestinal infection intensities between fur seal pups with and without peritoneal infections. Female adult hookworms in the intestines of both host species were significantly larger than males, and sea lion hookworms were larger than those in fur seals. Worms in the intestine also were larger than worms found in the PNC. Gene sequencing and (RFLP) analysis of (PCR) amplified (ITS) ribosomal DNA were used to diagnose the species of 172 hookworms recovered from the PNC and intestine of 18 C. ursinus and seven Z. californianus hosts

A deterministic and stochastic velocity model for the Salton Trough/Basin and Range transition zone and constraints on magmatism during rifting

NASA Astrophysics Data System (ADS)

Larkin, Steven P.; Levander, Alan; Okaya, David; Goff, John A.

1996-12-01

As a high resolution addition to the 1992 Pacific to Arizona Crustal Experiment (PACE), a 45-km-long deep crustal seismic reflection profile was acquired across the Chocolate Mountains in southeastern California to illuminate crustal structure in the transition between the Salton Trough and the Basin and Range province. The complex seismic data are analyzed for both large-scale (deterministic) and fine-scale (stochastic) crustal features. A low-fold near-offset common-midpoint (CMP) stacked section shows the northeastward lateral extent of a high-velocity lower crustal body which is centered beneath the Salton Trough. Off-end shots record a high-amplitude diffraction from the point where the high velocity lower crust pinches out at the Moho. Above the high-velocity lower crust, moderate-amplitude reflections occur at midcrustal levels. These reflections display the coherency and frequency characteristics of reflections backscattered from a heterogeneous velocity field, which we model as horizontal intrusions with a von Kármán (fractal) distribution. The effects of upper crustal scattering are included by combining the mapped surface geology and laboratory measurements of exposed rocks within the Chocolate Mountains to reproduce the upper crustal velocity heterogeneity in our crustal velocity model. Viscoelastic finite difference simulations indicate that the volume of mafic material within the reflective zone necessary to produce the observed backscatter is about 5%. The presence of wavelength-scale heterogeneity within the near-surface, upper, and middle crust also produces a 0.5-s-thick zone of discontinuous reflections from a crust-mantle interface which is actually a first-order discontinuity.

Molecular and morphometric evidence for separate species of Uncinaria (Nematoda: Ancylostomatidae) in California sea lions and northern fur seals: hypothesis testing supplants verification.

PubMed

Nadler, S A; Adams, B J; Lyons, E T; DeLong, R L; Melin, S R

2000-10-01

California sea lions (Zalophus californianus) and northern fur seals (Callorhinus ursinus) are each believed to host distinct hookworm species (Uncinaria spp.). However, a recent morphometric analysis suggested that a single species parasitizes multiple pinniped hosts, and that the observed differences are host-induced. To explore the systematics of these hookworms and test these competing hypotheses, we obtained nucleotide sequences of nuclear ribosomal DNA (D2/D3 28S, D18/D19 28S, and internal transcribed spacer [ITS] regions) from 20 individual hookworms parasitizing California sea lion and northern fur seal pups where their breeding grounds are sympatric. Five individuals from an allopatric population of California sea lions were also sampled for ITS-1 and D18/D19 28S sequences. The 28S D2/D3 sequences showed no diagnostic differences among hookworms sampled from individual sea lions and fur seals, whereas the 28S D18/D19 sequences had one derived (apomorphic) character demarcating hookworms from northern fur seals. ITS sequences were variable for 7 characters, with 4 derived (apomorphic) states in ITS-1 demarcating hookworms from California sea lions. Multivariate analysis of morphometric data also revealed significant differences between nematodes representing these 2 host-associated lineages. These results indicate that these hookworms represent 2 species that are not distributed indiscriminately between these host species, but instead exhibit host fidelity, evolving independently with each respective host species. This evolutionary approach to analyzing sequence data for species delimitation is contrasted with similarity-based methods that have been applied to numerous diagnostic studies of nematode parasites.

Description of Uncinaria lyonsi n. sp. (Nematoda: Ancylostomatidae) from the California sea lion Zalophus californianus Lesson (Carnivora: Otariidae).

PubMed

Kuzmina, Tetiana A; Kuzmin, Yuriy

2015-02-01

A new species of hookworm, Uncinaria lyonsi n. sp., is described based on morphological studies of the nematodes collected by Dr. E. T. Lyons from the California sea lion Zalophus californianus (Lesson) on San Miguel Island, California, USA. The new species is morphologically similar to three other species of the genus Uncinaria Frölich, 1789 parasitising pinnipeds, U. lucasi Stiles, 1901, U. hamiltoni Baylis, 1933 and U. sanguinis Marcus, Higgins, Šlapeta & Gray, 2014, in the body dimensions, the structure of the buccal capsule, the shape and structure of the male caudal bursa and female genital system. Uncinaria lyonsi n. sp. is differentiated from U. lucasi by having longer spicules and gubernaculum, larger buccal capsule and more slender oesophagus. The new species differs from U. hamiltoni and U. sanguinis in having shorter spicules and narrower buccal capsule. The latter two species also occur in the Southern Hemisphere and are geographically separated from U. lyonsi n. sp. The present study confirms the existence of a host-specific species of Uncinaria in the California sea lion, previously revealed by molecular and biological investigations.

Molecular Epidemiology of Cryptosporidium spp. and Giardia spp. in Mussels (Mytilus californianus) and California Sea Lions (Zalophus californianus) from Central California

PubMed Central

Adell, A. D.; Shapiro, K.; Melli, A.; Conrad, P. A.

2014-01-01

Cryptosporidium and Giardia are of public health importance, with recognized transmission through recreational waters. Therefore, both can contaminate marine waters and shellfish, with potential to infect marine mammals in nearshore ecosystems. A 2-year study was conducted to evaluate the presence of Cryptosporidium and Giardia in mussels located at two distinct coastal areas in California, namely, (i) land runoff plume sites and (ii) locations near sea lion haul-out sites, as well as in feces of California sea lions (CSL) (Zalophus californianus) by the use of direct fluorescent antibody (DFA) detection methods and PCR with sequence analysis. In this study, 961 individual mussel hemolymph samples, 54 aliquots of pooled mussel tissue, and 303 CSL fecal samples were screened. Giardia duodenalis assemblages B and D were detected in hemolymph from mussels collected near two land runoff plume sites (Santa Rosa Creek and Carmel River), and assemblages C and D were detected in hemolymph from mussels collected near a sea lion haul-out site (White Rock). These results suggest that mussels are being contaminated by protozoa carried in terrestrial runoff and/or shed in the feces of CSL. Furthermore, low numbers of oocysts and cysts morphologically similar to Cryptosporidium and Giardia, respectively, were detected in CSL fecal samples, suggesting that CSL could be a source and a host of protozoan parasites in coastal environments. The results of this study showed that Cryptosporidium and Giardia spp. from the feces of terrestrial animals and CSL can contaminate mussels and coastal environments. PMID:25281384

Molecular epidemiology of Cryptosporidium spp. and Giardia spp. in mussels (Mytilus californianus) and California sea lions (Zalophus californianus) from Central California.

PubMed

Adell, A D; Smith, W A; Shapiro, K; Melli, A; Conrad, P A

2014-12-01

Cryptosporidium and Giardia are of public health importance, with recognized transmission through recreational waters. Therefore, both can contaminate marine waters and shellfish, with potential to infect marine mammals in nearshore ecosystems. A 2-year study was conducted to evaluate the presence of Cryptosporidium and Giardia in mussels located at two distinct coastal areas in California, namely, (i) land runoff plume sites and (ii) locations near sea lion haul-out sites, as well as in feces of California sea lions (CSL) (Zalophus californianus) by the use of direct fluorescent antibody (DFA) detection methods and PCR with sequence analysis. In this study, 961 individual mussel hemolymph samples, 54 aliquots of pooled mussel tissue, and 303 CSL fecal samples were screened. Giardia duodenalis assemblages B and D were detected in hemolymph from mussels collected near two land runoff plume sites (Santa Rosa Creek and Carmel River), and assemblages C and D were detected in hemolymph from mussels collected near a sea lion haul-out site (White Rock). These results suggest that mussels are being contaminated by protozoa carried in terrestrial runoff and/or shed in the feces of CSL. Furthermore, low numbers of oocysts and cysts morphologically similar to Cryptosporidium and Giardia, respectively, were detected in CSL fecal samples, suggesting that CSL could be a source and a host of protozoan parasites in coastal environments. The results of this study showed that Cryptosporidium and Giardia spp. from the feces of terrestrial animals and CSL can contaminate mussels and coastal environments. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Trace elements in blood of sea turtles Lepidochelys olivacea in the Gulf of California, Mexico.

PubMed

Zavala-Norzagaray, A A; Ley-Quiñónez, C P; Espinosa-Carreón, T L; Canizalez-Román, A; Hart, C E; Aguirre, A A

2014-11-01

This study determined the concentrations of heavy metals in blood collected from Pacific Ridley sea turtles (Lepidochelys olivacea) inhabiting the coast of Guasave, Mexico, in the Gulf of California. The highest reported metal concentration in blood was Zn, followed by Se. Of nonessential toxic metals, As was reported in higher percentage compared to Cd. The concentrations of metals detected were present as follows: Zn > Se > Mn > As > Ni > Cd > Cu. Cd concentration in blood is higher in our population in comparison with other populations of L. olivacea, and even higher in other species of sea turtles. Our study reinforces the usefulness of blood for the monitoring of the levels of contaminating elements, and is easily accessible and nonlethal for sea turtles.

An Overview of Geologic Carbon Sequestration Potential in California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cameron Downey; John Clinkenbeard

2005-10-01

As part of the West Coast Regional Carbon Sequestration Partnership (WESTCARB), the California Geological Survey (CGS) conducted an assessment of geologic carbon sequestration potential in California. An inventory of sedimentary basins was screened for preliminary suitability for carbon sequestration. Criteria included porous and permeable strata, seals, and depth sufficient for critical state carbon dioxide (CO{sub 2}) injection. Of 104 basins inventoried, 27 met the criteria for further assessment. Petrophysical and fluid data from oil and gas reservoirs was used to characterize both saline aquifers and hydrocarbon reservoirs. Where available, well log or geophysical information was used to prepare basin-wide mapsmore » showing depth-to-basement and gross sand distribution. California's Cenozoic marine basins were determined to possess the most potential for geologic sequestration. These basins contain thick sedimentary sections, multiple saline aquifers and oil and gas reservoirs, widespread shale seals, and significant petrophysical data from oil and gas operations. Potential sequestration areas include the San Joaquin, Sacramento, Ventura, Los Angeles, and Eel River basins, followed by the smaller Salinas, La Honda, Cuyama, Livermore, Orinda, and Sonoma marine basins. California's terrestrial basins are generally too shallow for carbon sequestration. However, the Salton Trough and several smaller basins may offer opportunities for localized carbon sequestration.« less

Dissecting the Influences of Climate and Demography on the Dynamics of Leptospirosis in California Sea Lions

USDA-ARS?s Scientific Manuscript database

Leptospirosis is a zoonotic infection of global importance, yet its population dynamics remain poorly understood. We present the first empirically-motivated study of the dynamics of leptospirosis, drawing on a unique 24-year time series of disease in California sea lions (CSLs). Since the early 19...

Reducing sediment and phosphorus in tributary waters with alum and polyacrylamide.

PubMed

Mason, L B; Amrhein, C; Goodson, C C; Matsumoto, M R; Anderson, M A

2005-01-01

The Salton Sea is the largest inland water body in California, covering an area of 980 km(2). Inflow to the Salton Sea (1.6 km(3) yr(-1)) is predominately nutrient-rich agricultural wastewater, which has led to eutrophication. Because internal phosphorus release from the bottom sediments is comparatively low and external phosphorus loading to the Salton Sea is high, reduction of tributary phosphorus is expected to reduce algal blooms, increase dissolved oxygen, and reduce odors. Removing both dissolved phosphorus and phosphorus-laden sediment from agricultural drainage water (ADW) should decrease eutrophication. Both alum and polyacrylamide (PAM) are commonly used in wastewater treatment to remove phosphorus and sediment and were tested for use in tributary waters. Laboratory jar tests determined PAM effectiveness (2 mg L(-1)) for turbidity reduction as cationic > anionic = nonionic. Although cationic PAM was the most effective at reducing turbidity at higher speeds, there was no observed difference between the neutral and anionic PAMs at velocity gradients of 18 to 45 s(-1). Alum (4 mg L(-1) Al) reduced turbidity in low energy systems (velocity gradients < 10 s(-1)) by 95% and was necessary to reduce soluble phosphorus, which comprises 47 to 100% of the total P concentration in the tributaries. When PAM was added with alum, the anionic PAM became ineffective in aiding flocculation. The nonionic PAM (2 mg L(-1)) + alum (4 mg L(-1) Al) is recommended to reduce suspended solids in higher energy systems and reduce soluble P by 93%.

Terrestrial source to deep-sea sink sediment budgets at high and low sea levels: Insights from tectonically active Southern California

USGS Publications Warehouse

Covault, J.A.; Romans, B.W.; Graham, S.A.; Fildani, A.; Hilley, G.E.

2011-01-01

Sediment routing from terrestrial source areas to the deep sea influences landscapes and seascapes and supply and filling of sedimentary basins. However, a comprehensive assessment of land-to-deep-sea sediment budgets over millennia with significant climate change is lacking. We provide source to sink sediment budgets using cosmogenic radionuclide-derived terrestrial denudation rates and submarine-fan deposition rates through sea-level fluctuations since oxygen isotope stage 3 (younger than 40 ka) in tectonically active, spatially restricted sediment-routing systems of Southern California. We show that source-area denudation and deep-sea deposition are balanced during a period of generally falling and low sea level (40-13 ka), but that deep-sea deposition exceeds terrestrial denudation during the subsequent period of rising and high sea level (younger than 13 ka). This additional supply of sediment is likely owed to enhanced dispersal of sediment across the shelf caused by seacliff erosion during postglacial shoreline transgression and initiation of submarine mass wasting. During periods of both low and high sea level, land and deep-sea sediment fluxes do not show orders of magnitude imbalances that might be expected in the wake of major sea-level changes. Thus, sediment-routing processes in a globally significant class of small, tectonically active systems might be fundamentally different from those of larger systems that drain entire orogens, in which sediment storage in coastal plains and wide continental shelves can exceed millions of years. Furthermore, in such small systems, depositional changes offshore can reflect onshore changes when viewed over time scales of several thousand years to more than 10 k.y. ?? 2011 Geological Society of America.

Sea level response to ENSO along the central California coast: How the 1997-1998 event compares with the historic record

USGS Publications Warehouse

Ryan, H.F.; Noble, M.

2002-01-01

Long-term monthly sea level and sea surface temperature (SST) anomalies from central California show that during winter months, positive anomalies are associated with El Nin??o events and the negative ones with La Nin??a events. There is no significant impact on monthly mean anomalies associated with Pacific decadal oscillations, although there is a tendency for more extreme events and greater variance during positive decadal oscillations. The very strong 1997-1998 El Nin??o was analyzed with respect to the long-term historic record to assess the forcing mechanisms for sea level and SST. Beginning in the spring of 1997, we observed several long-period (> 30days) fluctuations in daily sea level with amplitudes of over 10 cm at San Francisco, California. Fluctuations of poleward long-period alongshore wind stress anomalies (AWSA) are coherent with the sea level anomalies. However, the wind stress cannot entirely account for the observed sea level signals. The sea level fluctuations are also correlated with sea level fluctuations observed further south at Los Angeles and Tumaco, Columbia, which showed a poleward phase propagation of the sea level signal. We suggest that the sea level fluctuations were, to a greater degree, forced by the passage of remotely generated and coastally trapped waves that were generated along the equator and propagated to the north along the west coast of North America. However, both local and remote AWSA can significantly modulate the sea level signals. The arrival of coastally trapped waves began in the spring of 1997, which is earlier than previous strong El Nin??o events such as the 1982-1983 event. Published by Elsevier Science Ltd.

Novel symptomatology and changing epidemiology of domoic acid toxicosis in California sea lions (Zalophus californianus): an increasing risk to marine mammal health

PubMed Central

Goldstein, T; Mazet, J.A.K; Zabka, T.S; Langlois, G; Colegrove, K.M; Silver, M; Bargu, S; Van Dolah, F; Leighfield, T; Conrad, P.A; Barakos, J; Williams, D.C; Dennison, S; Haulena, M; Gulland, F.M.D

2007-01-01

Harmful algal blooms are increasing worldwide, including those of Pseudo-nitzschia spp. producing domoic acid off the California coast. This neurotoxin was first shown to cause mortality of marine mammals in 1998. A decade of monitoring California sea lion (Zalophus californianus) health since then has indicated that changes in the symptomatology and epidemiology of domoic acid toxicosis in this species are associated with the increase in toxigenic blooms. Two separate clinical syndromes now exist: acute domoic acid toxicosis as has been previously documented, and a second novel neurological syndrome characterized by epilepsy described here associated with chronic consequences of previous sub-lethal exposure to the toxin. This study indicates that domoic acid causes chronic damage to California sea lions and that these health effects are increasing. PMID:18006409

Penetration of the small intestine of a California sea lion (Zalophus californianus) pup by adult hookworms (Uncinaria spp).

PubMed

Spraker, T R; Lyons, E T; DeLong, R L; Zink, R R

2004-03-01

During a study on the mortality of California sea lion (Zalophus californianus) pups born on San Miguel Island, California in 2002, two adult female hookworms (Uncinaria spp) were found penetrating the serosal surface of the intestinal wall and protruding into the peritoneal cavity of one pup. Documentation and a description of this unexpected finding and associated lesions are presented here. Also, adult hookworms were found in the peritoneal fluid of two other dead Z. californianus pups.

Sea-Level Rise and Flood Potential along the California Coast

NASA Astrophysics Data System (ADS)

Delepine, Q.; Leung, C.

2013-12-01

Sea-level rise is becoming an ever-increasing problem in California. Sea-level is expected to rise significantly in the next 100 years, which will raise flood elevations in coastal communities. This will be an issue for private homeowners, businesses, and the state. One study suggests that Venice Beach could lose a total of at least $440 million in tourism spending and tax dollars from flooding and beach erosion if sea level rises 1.4 m by 2100. In addition, several airports, such as San Francisco International Airport, are located in coastal regions that have flooded in the past and will likely be flooded again in the next 30 years, but sea-level rise is expected to worsen the effects of flooding in the coming decades It is vital for coastal communities to understand the risks associated with sea-level rise so that they can plan to adapt to it. By obtaining accurate LiDAR elevation data from the NOAA Digital Coast Website (http://csc.noaa.gov/dataviewer/?keyword=lidar#), we can create flood maps to simulate sea level rise and flooding. The data are uploaded to ArcGIS and contour lines are added for different elevations that represent future coastlines during 100-year flooding. The following variables are used to create the maps: 1. High-resolution land surface elevation data - obtained from NOAA 2. Local mean high water level - from USGS 3. Local 100-year flood water level - from the Pacific Institute 4. Sea-level rise projections for different future dates (2030, 2050, and 2100) - from the National Research Council The values from the last three categories are added to represent sea-level rise plus 100-year flooding. These values are used to make the contour lines that represent the projected flood elevations, which are then exported as KML files, which can be opened in Google Earth. Once these KML files are made available to the public, coastal communities will gain an improved understanding of how flooding and sea-level rise might affect them in the future

Chronic pancreatitis with secondary diabetes mellitus treated by use of insulin in an adult California sea lion.

PubMed

Meegan, Jenny M; Sidor, Inga F; Steiner, Jörg M; Sarran, Delphine; Dunn, J Lawrence

2008-06-01

A 21-year-old neutered male captive California sea lion developed chronic polyuria; polydipsia; polyphagia; accelerated development of existing cataracts; and frequent episodes of gastrointestinal upset including anorexia, signs of abdominal discomfort, diarrhea, and vomiting. Chronic hypercholesterolemia, hypertriglyceridemia, hyperglycemia, and glucosuria were identified. During episodes of gastrointestinal abnormalities, transient hyperbilirubinemia and increased serum J-glutamyltransferase activities developed. Clinical findings strongly suggested chronic pancreatitis with secondary diabetes mellitus and intermittent cholestasis. Multiple diagnostic tests, including abdominal ultrasonography, serial hematologic and serum biochemical analyses, fecal examinations, urinalyses and bacteriologic culture of urine, measurement of serum fructosamine and insulin concentrations, and evaluation of thyroid and adrenal function, did not reveal any specific parasitic, endocrine, hepatic, or neoplastic etiologies. For 1.5 years, the sea lion received once-daily administration of glargine insulin, gastrointestinal protectants, and a strict high-protein, low-fat diet. Daily monitoring of glucose regulation was achieved by training the sea lion to submit to blood and urine sampling. Glucose regulation ranged from fair to good, and clinical signs of diabetes mellitus lessened. Episodes of gastrointestinal upset still occurred, although the frequency and severity decreased. Ultimately, a severe episode developed, associated with diabetic ketoacidosis and sepsis, and the sea lion died. Severe fibrosing pancreatitis with exocrine and endocrine atrophy and abscesses arising from ectatic pancreatic ducts were found. Peripancreatic fibrosis caused stricture of the common bile duct, resulting in gallbladder distension without cholecystitis. Diabetes mellitus can occur secondary to chronic pancreatitis in California sea lions and insulin therapy should be considered.

Prolonged California aridity linked to climate warming and Pacific sea surface temperature.

PubMed

MacDonald, Glen M; Moser, Katrina A; Bloom, Amy M; Potito, Aaron P; Porinchu, David F; Holmquist, James R; Hughes, Julia; Kremenetski, Konstantine V

2016-09-15

California has experienced a dry 21(st) century capped by severe drought from 2012 through 2015 prompting questions about hydroclimatic sensitivity to anthropogenic climate change and implications for the future. We address these questions using a Holocene lake sediment record of hydrologic change from the Sierra Nevada Mountains coupled with marine sediment records from the Pacific. These data provide evidence of a persistent relationship between past climate warming, Pacific sea surface temperature (SST) shifts and centennial to millennial episodes of California aridity. The link is most evident during the thermal-maximum of the mid-Holocene (~8 to 3 ka; ka = 1,000 calendar years before present) and during the Medieval Climate Anomaly (MCA) (~1 ka to 0.7 ka). In both cases, climate warming corresponded with cooling of the eastern tropical Pacific despite differences in the factors producing increased radiative forcing. The magnitude of prolonged eastern Pacific cooling was modest, similar to observed La Niña excursions of 1(o) to 2 °C. Given differences with current radiative forcing it remains uncertain if the Pacific will react in a similar manner in the 21st century, but should it follow apparent past behavior more intense and prolonged aridity in California would result.

Sea-level rise and coastal groundwater inundation and shoaling at select sites in California, USA

USGS Publications Warehouse

Hoover, Daniel J.; Odigie, Kingsley; Swarzenski, Peter W.; Barnard, Patrick

2017-01-01

Study regionThe study region spans coastal California, USA, and focuses on three primary sites: Arcata, Stinson Beach, and Malibu Lagoon.Study focus1 m and 2 m sea-level rise (SLR) projections were used to assess vulnerability to SLR-driven groundwater emergence and shoaling at select low-lying, coastal sites in California. Separate and combined inundation scenarios for SLR and groundwater emergence were developed using digital elevation models of study site topography and groundwater surfaces constructed from well data or published groundwater level contours.New hydrological insights for the regionSLR impacts are a serious concern in coastal California which has a long (∼1800 km) and populous coastline. Information on the possible importance of SLR-driven groundwater inundation in California is limited. In this study, the potential for SLR-driven groundwater inundation at three sites (Arcata, Stinson Beach, and Malibu Lagoon) was investigated under 1 m and 2 m SLR scenarios. These sites provide insight into the vulnerability of Northern California coastal plains, coastal developments built on beach sand or sand spits, and developed areas around coastal lagoons associated with seasonal streams and berms. Northern California coastal plains with abundant shallow groundwater likely will see significant and widespread groundwater emergence, while impacts along the much drier central and southern California coast may be less severe due to the absence of shallow groundwater in many areas. Vulnerability analysis is hampered by the lack of data on shallow coastal aquifers, which commonly are not studied because they are not suitable for domestic or agricultural use. Shallow saline aquifers may be present in many areas along coastal California, which would dramatically increase vulnerability to SLR-driven groundwater emergence and shoaling. Improved understanding of the extent and response of California coastal aquifers to SLR will help in preparing for mitigation

Obsidian hydration dating of volcanic events

USGS Publications Warehouse

Friedman, I.; Obradovich, J.

1981-01-01

Obsidian hydration dating of volcanic events had been compared with ages of the same events determined by the 14C and KAr methods at several localities. The localities, ranging in age from 1200 to over 1 million yr, include Newberry Craters, Oregon; Coso Hot Springs, California; Salton Sea, California; Yellowstone National Park, Wyoming; and Mineral Range, Utah. In most cases the agreement is quite good. A number of factors including volcanic glass composition and exposuretemperature history must be known in order to relate hydration thickness to age. The effect of composition can be determined from chemical analysis or the refractive index of the glass. Exposure-temperature history requires a number of considerations enumerated in this paper. ?? 1981.

Sea surface and remotely sensed temperatures off Cape Mendocino, California

NASA Technical Reports Server (NTRS)

Breaker, L. C.; Arvesen, J. C.; Frydenlund, D.; Myers, J. S.; Short, K.

1985-01-01

During September 3 to 5, 1979, a multisensor oceanographic experiment was conducted off Cape Mendocino, California. The purpose of this experiment was to validate the use of remote sensing techniques over an area along the U.S. west coast where coasted upwelling is known to be intense. Remotely sensed mutlispectral data, including thermal infrared imagery, were collected above an upwelling feature off Cape Mendocino. Data were acquired from the TIRNOS-N and NOAA-6 polar orbiting satellites, the NASA Ames Research Center's high altitude U-2 aircraft, and a U.S. Coast Guard C-130 aircraft. Supporting surface truth data over the same feature were collected aboard the National Oceanic and Atmospheric Administration (NOAA) ship, OCEANOGRAPHER. Atmospheric soundings were also taken aboard the ship. The results indicate that shipboard measurements of sea surface temperatures can be reproduction within 1 C or better through remote observation of absolute infrared radiance values (whether measured aboard the NOAA polar orbiting satellite, the U-2 aircraft, or the Coast Guard aircraft) by using appropriate atmospheric corrections. Also, the patterns of sea surface temperature which were derived independently from the various remote platforms provide a consistent interpretation of the surface temperature field.

Climatic anomaly affects the immune competence of California sea lions

PubMed Central

Banuet-Martínez, Marina; Espinosa-de Aquino, Wendy; Elorriaga-Verplancken, Fernando R.; Flores-Morán, Adriana; García, Olga P.; Camacho, Mariela

2017-01-01

The past decades have been characterized by a growing number of climatic anomalies. As these anomalies tend to occur suddenly and unexpectedly, it is often difficult to procure empirical evidence of their effects on natural populations. We analysed how the recent sea surface temperature (SST) anomaly in the northeastern Pacific Ocean affects body condition, nutritional status, and immune competence of California sea lion pups. We found that pup body condition and blood glucose levels of the pups were lower during high SST events, although other biomarkers of malnutrition remained unchanged, suggesting that pups were experiencing early stages of starvation. Glucose-dependent immune responses were affected by the SST anomaly; specifically, pups born during high SST events had lower serum concentrations of IgG and IgA, and were unable to respond to an immune challenge. This means that not only were pups that were born during the SST anomaly less able to synthesize protective antibodies; they were also limited in their ability to respond rapidly to nonspecific immune challenges. Our study provides empirical evidence that atypical climatic conditions can limit energetic reserves and compromise physiological responses that are essential for the survival of a marine top predator. PMID:28658317

Lithospheric Structure and Active Deformation in the Salton Trough from Coseismic and Postseismic Models of the 2010 Mw 7.2 El Mayor-Cucapah Earthquake

NASA Astrophysics Data System (ADS)

Fielding, E. J.; Huang, M. H.; Dickinson, H.; Freed, A. M.; Burgmann, R.; Gonzalez-Ortega, J. A.; Andronicos, C.

2016-12-01

The 4 April 2010 Mw 7.2 El Mayor-Cucapah (EMC) Earthquake ruptured about 120 km along several NW-striking faults to the west of the Cerro Prieto Fault in the Salton Trough of Baja California, Mexico. We analyzed interferometric synthetic aperture radar (SAR), SAR and optical pixel offsets, and continuous and campaign GPS data to optimize an EMC coseismic rupture model with 9 fault segments, which fits the complex structure of the faults. Coseismic slip inversion with a layered elastic model shows that largely right-lateral slip is confined to upper 10 km with strong variations along strike. Near-field GPS measures slip on a north-striking normal fault that ruptured at the beginning of the earthquake, previously inferred from seismic waveforms. EMC Earthquake postseismic deformation shows the Earth's response to the large coseismic stress changes. InSAR shows rapid shallow afterslip at the north and south ends of the main ruptures. Continuous GPS from the Plate Boundary Observatory operated by UNAVCO measures the first six years of postseismic deformation, extremely rapid near the rupture. Afterslip on faults beneath the coseismic rupture cannot explain far-field displacements that are best explained by viscoelastic relaxation of the lower crust and upper mantle. We built a viscoelastic 3D finite element model of the lithosphere and asthenosphere based on available data for the region with the EMC coseismic faults embedded inside. Coseismic slip was imposed on the model, allowed to relax for 5 years, and then compared to the observed surface deformation. Systematic exploration of the viscoelastic parameters shows that horizontal and vertical heterogeneity is required to fit the postseismic deformation. Our preferred viscoelastic model has weaker viscosity layers beneath the Salton Trough than adjacent blocks that are consistent with the inferred differences in the geotherms. Defining mechanical lithosphere as rocks that have viscosities greater than 10^19 Pa s (able

Sea Level Rise Drove Enhanced Coastal Erosion following the Last Glacial Maximum, Southern California, U.S.A.

NASA Astrophysics Data System (ADS)

Sharman, G.; Covault, J. A.; Stockli, D. F.; Sickmann, Z.; Malkowski, M. A.; Johnstone, S.

2017-12-01

Seacliff erosion poses a major threat to southern California coastal communities, including the propensity for episodic cliff failure and damage to residential and commercial property. Rising sea level is predicted to accelerate seacliff retreat, yet few constraints exist on how rapid sea level rise influenced coastal erosion rates in pre-modern timescales. Here we look to the geologic record in submarine fans to investigate changes in relative sediment supply from rivers and coastal erosion, the latter including seacliff retreat and bluffland erosion. To understand how sea level rise driven by past global warming impacted coastal erosion rates, we sampled modern rivers of the Peninsular Ranges and latest Pleistocene-Holocene submarine canyon-fan systems in southern California for detrital zircon U-Pb geochronology (1369 analyses from 10 samples). Modern river samples show a systematic north-south change in grain age populations broadly distributed across Cretaceous time (ca. 70-135 Ma) to a predominance of middle Cretaceous grain ages (ca. 95-115 Ma), reflecting variations in the geologic age of units within each river catchment. The Carlsbad and La Jolla submarine canyon-fan systems, deposited during sea level lowstand and highstand, respectively, exhibit detrital zircon age distributions consistent with derivation from upstream rivers, with mixing in the littoral zone. However, a sample from the Oceanside fan, deposited during rapid sea level rise at ca. 13 ka, is dominated by detrital ages that lack a local source in the northern Peninsular Ranges, including latest Cretaceous, late Jurassic, and Proterozoic ages. However, such grain ages are widespread in Paleogene sedimentary rocks that comprise the shelf and coastal area, suggesting increased sediment supply from coastal and shelf erosion. Assuming that the Oceanside sample is representative of sediment production during sea level rise, sediment mixing calculations suggest a one to two orders of magnitude

Butyltin residues in southern sea otters (Enhydra lutris nereis) found dead along California coastal waters

USGS Publications Warehouse

Kannan, K.; Guruge, K.S.; Thomas, N.J.; Tanabe, S.; Giesy, J.P.

1998-01-01

Tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT), were determined in liver, kidney, and brain tissues of adult southern sea otters (Enhydra lutris nereis) found dead along the coast of California during 1992a??1996. Hepatic concentrations of butyltin compounds (BTs = MBT + DBT + TBT) ranged from 40 to 9200 ng/g wet wt, which varied depending on the sampling location and gender. Concentrations of BTs in sea otters were comparable to those reported in stranded bottlenose dolphins from the U.S. Atlantic Coast during 1989a??1994. Greater accumulation of butyltins in sea otters was explained by their bottom-feeding habit and the diet that consists exclusively of invertebrates such as mollusks and gastropods. Livers of female sea otters contained approximately 2-fold greater concentrations of BTs than did those of males. The composition of butyltin compounds in sea otter tissues was predominated by TBT in most cases and suggestive of recent exposure. Large harbors such as Monterey Harbor that handle ships legally painted with TBT-containing antifouling paints continued to experience ecotoxicologically significant butyltin contamination. Sea otters, which were affected by infectious diseases, contained greater concentrations of BTs in their tissues than those that died from trauma and other unknown causes.

Remotely sensed sea surface temperature variability off California during a 'Santa Ana' clearing

NASA Technical Reports Server (NTRS)

Lynn, R. J.; Svejkovsky, J.

1984-01-01

Multichannel atmospheric correction equations for the NOAA 6 proposed by Bernstein (1982) and by McClain (1981) are evaluated by using satellite and in situ data collected over and in the Southern California Bight. The temporal and spatial variation of sea surface temperature over small scales is estimated from the data, and the effect of this variation in matching satellite and in situ data sets is discussed. Changes in the temperature fields between images are examined for diurnal variation and for surface advection of horizontal temperature gradients.

Lithosphere thickness in the Gulf of California region

NASA Astrophysics Data System (ADS)

Fernández, Alejandra; Pérez-Campos, Xyoli

2017-11-01

The Gulf of California has a long tectonic history. Before the subduction of the Guadalupe and Magdalena plates ceased, extension of the Gulf began to the east, at the Basin and Range province. Later, it was focused west of the Sierra Madre Occidental and the opening of the Gulf started. Currently, the Gulf rifting has different characteristics to the north than to the south. In this study, we analyze the lithosphere thickness in the Gulf of California region by means of P-wave and S-wave receiver functions. We grouped our lithosphere-thickness estimates into five froups: 1) North of the Gulf, with a thin lithosphere ( 50 km) related to the extension observed in the Salton Through region; 2) the northwestern part of Baja California, with a thicker lithosphere ( 80 km), thinning towards the Gulf due to the extension and opening processes ( 65 km); 3) central Baja California, with no converted phase corresponding to the lithosphere-asthenosphere boundary but evidence of the presence of a slab remnant; 4) the southern Baja California peninsula, showing a shallow lithosphere-astenosphere boundary (LAB) (< 55 km) and a lithosphere thinning towards the Gulf; and 5) the eastern Gulf margin with lithosphere thinning towards the south. These groups can be further assembled into three regions: A) The northernmost Gulf, where both margins of the Gulf show a relatively constant lithosphere thickness, consistent with an old basement in Sonora and the presence of the Peninsular Ranges batholith in northern Baja California, thinning up towards the axis of the rift in the northernmost Gulf. B) Central and southern Gulf, where the lithosphere thickness in this region ranges from 40 to 55 km, which is consistent with the presence of a younger crust. C) Central Baja California peninsula, where LAB is not detected; but there is evidence of a slab remnant.

METAZOOPLANKTON DYNAMICS IN THE SALTON SEA, CALIFORNIA, 1997-1999. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

CHEMICAL AND PHYSICAL CHARACTERISTICS OF THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

PARASITES OF FISH FROM THE SALTON SEA, CALIFORNIA, USA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Sea Surface Temperature Influence on Terrestrial Gross Primary Production along the Southern California Current.

PubMed

Reimer, Janet J; Vargas, Rodrigo; Rivas, David; Gaxiola-Castro, Gilberto; Hernandez-Ayon, J Martin; Lara-Lara, Ruben

2015-01-01

Some land and ocean processes are related through connections (and synoptic-scale teleconnections) to the atmosphere. Synoptic-scale atmospheric (El Niño/Southern Oscillation [ENSO], Pacific Decadal Oscillation [PDO], and North Atlantic Oscillation [NAO]) decadal cycles are known to influence the global terrestrial carbon cycle. Potentially, smaller scale land-ocean connections influenced by coastal upwelling (changes in sea surface temperature) may be important for local-to-regional water-limited ecosystems where plants may benefit from air moisture transported from the ocean to terrestrial ecosystems. Here we use satellite-derived observations to test potential connections between changes in sea surface temperature (SST) in regions with strong coastal upwelling and terrestrial gross primary production (GPP) across the Baja California Peninsula. This region is characterized by an arid/semiarid climate along the southern California Current. We found that SST was correlated with the fraction of photosynthetic active radiation (fPAR; as a proxy for GPP) with lags ranging from 0 to 5 months. In contrast ENSO was not as strongly related with fPAR as SST in these coastal ecosystems. Our results show the importance of local-scale changes in SST during upwelling events, to explain the variability in GPP in coastal, water-limited ecosystems. The response of GPP to SST was spatially-dependent: colder SST in the northern areas increased GPP (likely by influencing fog formation), while warmer SST at the southern areas was associated to higher GPP (as SST is in phase with precipitation patterns). Interannual trends in fPAR are also spatially variable along the Baja California Peninsula with increasing secular trends in subtropical regions, decreasing trends in the most arid region, and no trend in the semi-arid regions. These findings suggest that studies and ecosystem process based models should consider the lateral influence of local-scale ocean processes that could

Sea Surface Temperature Influence on Terrestrial Gross Primary Production along the Southern California Current

PubMed Central

Reimer, Janet J.; Vargas, Rodrigo; Rivas, David; Gaxiola-Castro, Gilberto; Hernandez-Ayon, J. Martin; Lara-Lara, Ruben

2015-01-01

Some land and ocean processes are related through connections (and synoptic-scale teleconnections) to the atmosphere. Synoptic-scale atmospheric (El Niño/Southern Oscillation [ENSO], Pacific Decadal Oscillation [PDO], and North Atlantic Oscillation [NAO]) decadal cycles are known to influence the global terrestrial carbon cycle. Potentially, smaller scale land-ocean connections influenced by coastal upwelling (changes in sea surface temperature) may be important for local-to-regional water-limited ecosystems where plants may benefit from air moisture transported from the ocean to terrestrial ecosystems. Here we use satellite-derived observations to test potential connections between changes in sea surface temperature (SST) in regions with strong coastal upwelling and terrestrial gross primary production (GPP) across the Baja California Peninsula. This region is characterized by an arid/semiarid climate along the southern California Current. We found that SST was correlated with the fraction of photosynthetic active radiation (fPAR; as a proxy for GPP) with lags ranging from 0 to 5 months. In contrast ENSO was not as strongly related with fPAR as SST in these coastal ecosystems. Our results show the importance of local-scale changes in SST during upwelling events, to explain the variability in GPP in coastal, water-limited ecosystems. The response of GPP to SST was spatially-dependent: colder SST in the northern areas increased GPP (likely by influencing fog formation), while warmer SST at the southern areas was associated to higher GPP (as SST is in phase with precipitation patterns). Interannual trends in fPAR are also spatially variable along the Baja California Peninsula with increasing secular trends in subtropical regions, decreasing trends in the most arid region, and no trend in the semi-arid regions. These findings suggest that studies and ecosystem process based models should consider the lateral influence of local-scale ocean processes that could

Punctuated Sediment Discharge during Early Pliocene Birth of the Colorado River: Evidence from Regional Stratigraphy, Sedimentology, and Paleontology

NASA Astrophysics Data System (ADS)

Dorsey, Rebecca J.; O'Connell, Brennan; McDougall, Kristin; Homan, Mindy B.

2018-01-01

discharge are assessed by comparing the depositional chronology to the record of global sea-level change. The lower Colorado River Valley and Salton Trough experienced marine transgression during a gradual fall in global sea level between 6.3 and 5.5 Ma, implicating tectonic subsidence as the main driver of latest Miocene relative sea-level rise. A major fall of global sea level at 5.3 Ma outpaced subsidence and drove regional delta progradation, earliest flushing of Colorado River sand into the northern Gulf of California, and erosion of Bouse basal carbonate and siliciclastic members. The lower Colorado River valley was re-flooded by shallow marine waters during smaller changes in global sea level 5.1-4.8 Ma, after the river first ran through it, which requires a mechanism to stop delivery of sand to the lower river valley. We propose that tectonically controlled subsidence along the lower Colorado River, upstream of the southern Bouse study area, temporarily trapped sediment and stopped delivery of sand to the lower river valley and northern Gulf of California for 200-300 kyr. Massive progradation of the fluvial-deltaic system back down the river valley into the Salton Trough starting 4.8-4.5 Ma apparently was driven by a huge increase in sediment discharge that overwhelmed the sediment-storage capacity of sub-basins along the lower river corridor and established the fully integrated river channel network. Accompanies Dorsey et al. "Punctuated sediment discharge during early Pliocene birth of the Colorado River: Evidence from regional stratigraphy, sedimentology, and paleontology". Accompanies Dorsey et al. "Punctuated sediment discharge during early Pliocene birth of the Colorado River: Evidence from regional stratigraphy, sedimentology, and paleontology". Accompanies Dorsey et al. "Punctuated sediment discharge during early Pliocene birth of the Colorado River: Evidence from regional stratigraphy, sedimentology, and paleontology".

Lithospheric thinning beneath rifted regions of Southern California.

PubMed

Lekic, Vedran; French, Scott W; Fischer, Karen M

2011-11-11

The stretching and break-up of tectonic plates by rifting control the evolution of continents and oceans, but the processes by which lithosphere deforms and accommodates strain during rifting remain enigmatic. Using scattering of teleseismic shear waves beneath rifted zones and adjacent areas in Southern California, we resolve the lithosphere-asthenosphere boundary and lithospheric thickness variations to directly constrain this deformation. Substantial and laterally abrupt lithospheric thinning beneath rifted regions suggests efficient strain localization. In the Salton Trough, either the mantle lithosphere has experienced more thinning than the crust, or large volumes of new lithosphere have been created. Lack of a systematic offset between surface and deep lithospheric deformation rules out simple shear along throughgoing unidirectional shallow-dipping shear zones, but is consistent with symmetric extension of the lithosphere.

Characterization of a novel papillomavirus species (ZcPV1) from two California sea lions (Zalophus californianus).

PubMed

Rivera, Rebecca; Robles-Sikisaka, Refugio; Hoffman, Elizabeth M; Stacy, Brian A; Jensen, Eric D; Nollens, Hendrik H; Wellehan, James F X

2012-03-23

A seven-year old California sea lion (Zalophus californianus) presented with focally extensive, bilaterally symmetric, proliferative axillary skin lesions and preputial lesions. A second California sea lion in the same population presented with similar proliferative lesions on the underside of the tail. Histopathology revealed epidermal hyperplasia with severe hyperkeratosis, with proliferating keratinocytes forming broad, branching pegs that extended into the dermis. Pan-papillomaviral consensus PCR was used to obtain initial E1 sequence template and the complete genome was determined using a combination of rolling circle amplification and specific-primer PCR. Analysis revealed a novel papillomavirus, Zalophus californianus papillomavirus 1 (ZcPV1), with seven open reading frames encoding five early proteins (E6, E7, E1, E2 and E4) and two late proteins (L1 and L2). Phylogenetic analysis revealed that (ZcPV1) is most closely related to Equine papillomavirus 1 (EcPV1) in the genus Zetapapillomavirus, and Canine papillomaviruses 3 and 4 (CPV3, CPV4) in the genus Chipapillomavirus. The lesions regressed without intervention over a period of several months. Copyright © 2011 Elsevier B.V. All rights reserved.

Accumulation pattern of organochlorine pesticides and polychlorinated biphenyls in sourthern sea otters (Enhydra lutris nereis) found stranded along coastal California, USA

USGS Publications Warehouse

Nakata, H.; Kannan, K.; Jing, L.; Thomas, N.J.; Tanabe, S.; Giesy, J.P.

1998-01-01

Concentrations of PCBs, DDTs (p,p'-DDE, p,p'-DDD and p,p'-DDT), HCHs (α-, β-, γ-isomers), chlordanes (trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor and oxychlordane) and HCB (hexachlorobenzene were measured in liver, kidney and brain tissues of adult southern sea otters (Enhydra lutris nereis) found stranded along coastal California, USA, during 1992–96. The contamination pattern of organochlorines in sea otters from several locations was in the order of DDTs > PCBs > > CHLs > HCHs > > HCB, whereas those from Monterey Harbor contained greater concentrations of PCBs than of DDTs. Hepatic concentrations of PCBs and DDTs were in the ranges of 58–8700 and 280–5900 ng/g, wet weight, respectively, which varied depending on the geographic location. Sea otters collected from Monterey Harbor contained the greatest concentrations of PCBs and DDTs. In general, accumulation of DDTs, CHLs and PCBs was greater in kidney than in liver, whereas that of HCHs was similar in both the tissues. The gender difference in organochlorine concentrations was less than those reported in cetaceans. The composition of DDTs, HCHs and CHLs compounds in sea otter tissues indicated no recent inputs of these compounds in coastal California. Sea otters that died from infectious diseases, neoplasia and emaciation contained higher concentrations of DDTs than those that died from trauma.

Salton Seismic Imaging Project Line 5—the San Andreas Fault and Northern Coachella Valley Structure, Riverside County, California

NASA Astrophysics Data System (ADS)

Rymer, M. J.; Fuis, G.; Catchings, R. D.; Goldman, M.; Tarnowski, J. M.; Hole, J. A.; Stock, J. M.; Matti, J. C.

2012-12-01

The Salton Seismic Imaging Project (SSIP) is a large-scale, active- and passive-source seismic project designed to image the San Andreas Fault (SAF) and the adjacent basins (Imperial and Coachella Valleys) in southern California. Here, we focus on SSIP Line 5, one of four 2-D NE-SW-oriented seismic profiles that were acquired across the Coachella Valley. The 38-km-long SSIP-Line-5 seismic profile extends from the Santa Rosa Ranges to the Little San Bernardino Mountains and crosses both strands of the SAF, the Mission Creek (MCF) and Banning (BF) strands, near Palm Desert. Data for Line 5 were generated from nine buried explosive sources (most spaced about 2 to 8 km apart) and were recorded on approximately 281 Texan seismographs (average spacing 138 m). First-arrival refractions were used to develop a refraction tomographic velocity image of the upper crust along the seismic profile. The seismic data were also stacked and migrated to develop low-fold reflection images of the crust. From the surface to about 8 km depth, P-wave velocities range from about 2 km/s to more than 7.5 km/s, with the lowest velocities within a well-defined (~2-km-deep, 15-km-wide) basin (< 4 km/s), and the highest velocities below the transition from the Coachella Valley to the Santa Rosa Ranges on the southwest and within the Little San Bernardino Mountains on the northeast. The MCF and BF strands of the SAF bound an approximately 2.5-km-wide horst-type structure on the northeastern side of the Coachella Valley, beneath which the upper crust is characterized by a pronounced low-velocity zone that extends to the bottom of the velocity image. Rocks within the low-velocity zone have significantly lower velocities than those to the northeast and the southwest at the same depths. Conversely, the velocities of rocks on both sides of the Coachella Valley are greater than 7 km/s at depths exceeding about 4 km. The relatively narrow zone of shallow high-velocity rocks between the surface traces of

Projecting future sea level

USGS Publications Warehouse

Cayan, Daniel R.; Bromirski, Peter; Hayhoe, Katharine; Tyree, Mary; Dettinger, Mike; Flick, Reinhard

2006-01-01

California’s coastal observations and global model projections indicate that California’s open coast and estuaries will experience increasing sea levels over the next century. Sea level rise has affected much of the coast of California, including the Southern California coast, the Central California open coast, and the San Francisco Bay and upper estuary. These trends, quantified from a small set of California tide gages, have ranged from 10–20 centimeters (cm) (3.9–7.9 inches) per century, quite similar to that estimated for global mean sea level. So far, there is little evidence that the rate of rise has accelerated, and the rate of rise at California tide gages has actually flattened since 1980, but projections suggest substantial sea level rise may occur over the next century. Climate change simulations project a substantial rate of global sea level rise over the next century due to thermal expansion as the oceans warm and runoff from melting land-based snow and ice accelerates. Sea level rise projected from the models increases with the amount of warming. Relative to sea levels in 2000, by the 2070–2099 period, sea level rise projections range from 11–54 cm (4.3–21 in) for simulations following the lower (B1) greenhouse gas (GHG) emissions scenario, from 14–61 cm (5.5–24 in) for the middle-upper (A2) emission scenario, and from 17–72 cm (6.7–28 in) for the highest (A1fi) scenario. In addition to relatively steady secular trends, sea levels along the California coast undergo shorter period variability above or below predicted tide levels and changes associated with long-term trends. These variations are caused by weather events and by seasonal to decadal climate fluctuations over the Pacific Ocean that in turn affect the Pacific coast. Highest coastal sea levels have occurred when winter storms and Pacific climate disturbances, such as El Niño, have coincided with high astronomical tides. This study considers a range of projected future

California's Vulnerability to Volcanic Hazards: What's at Risk?

NASA Astrophysics Data System (ADS)

Mangan, M.; Wood, N. J.; Dinitz, L.

2015-12-01

California is a leader in comprehensive planning for devastating earthquakes, landslides, floods, and tsunamis. Far less attention, however, has focused on the potentially devastating impact of volcanic eruptions, despite the fact that they occur in the State about as frequently as the largest earthquakes on the San Andreas Fault Zone. At least 10 eruptions have occurred in the past 1,000 years—most recently in northern California (Lassen Peak 1914 to 1917)—and future volcanic eruptions are inevitable. The likelihood of renewed volcanism in California is about one in a few hundred to one in a few thousand annually. Eight young volcanoes, ranked as Moderate to Very High Threat [1] are dispersed throughout the State. Partially molten rock (magma) resides beneath at least seven of these—Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, and Salton Buttes— causing earthquakes, toxic gas emissions, hydrothermal activity, and (or) ground deformation. Understanding the hazards and identifying what is at risk are the first steps in building community resilience to volcanic disasters. This study, prepared in collaboration with the State of California Governor's Office of Emergency Management and the California Geological Survey, provides a broad perspective on the State's exposure to volcano hazards by integrating mapped volcano hazard zones with geospatial data on at-risk populations, infrastructure, and resources. The study reveals that ~ 16 million acres fall within California's volcano hazard zones, along with ~ 190 thousand permanent and 22 million transitory populations. Additionally, far-field disruption to key water delivery systems, agriculture, utilities, and air traffic is likely. Further site- and sector-specific analyses will lead to improved hazard mitigation efforts and more effective disaster response and recovery. [1] "Volcanic Threat and Monitoring Capabilities

Small-scale convection beneath the transverse ranges, California: Implications for interpretation of gravity anomalies

NASA Technical Reports Server (NTRS)

Humphreys, E. D.; Hager, B. H.

1985-01-01

Tomographic inversion of upper mantle P wave velocity heterogeneities beneath southern California shows two prominent features: an east-west trending curtain of high velocity material (up to 3% fast) in the upper 250 km beneath the Transverse Ranges and a region of low velocity material (up to 4% slow) in the 100 km beneath the Salton Trough. These seismic velocity anomalies were interpreted as due to small scale convection in the mantle. Using this hypothesis and assuming that temperature and density anomalies are linearly related to seismic velocity anomalies through standard coefficients of proportionality, leads to inferred variations of approx. + or - 300 C and approx. + or - 0.03 g/cc.

Combined use of remote sensing and seismic observations to infer geologically recent crustal deformation, active faulting, and stress fields. [California and Pennsylvania

NASA Technical Reports Server (NTRS)

Alexander, S. S. (Principal Investigator)

1982-01-01

Characteristic traits for earthquakes associated with strike-slip motion in Central California and the Salton Sea area, as revealed in ground based studies and LANDSAT imagery, were compared. The mapped lineaments are found to be oriented in several dominant directions. One direction is the same as the trend of the San Andreas fault. The other directions differ from area to area and may reflect the stresses of earlier geologic processes. The pattern of lineament orientations is significantly LANDSAT MSS data, SEASAT synthetic aperture radar data, and magnetic field data from the South Mountain area west of Gettysburg, Pennsylvania were registered to match each other in spatial position and merged. Pattern recognition techniques were applied to the composite data set to determine its utility in recognizing different rock types and structures in vegetated terrain around South Mountain. With the use of a texture algorithm to enhance geologic features, a classification of the entire area was made. A test of the correlation between SAR tone and texture, LANDSAT tone and texture, and magnetic field data revealed no tone or texture measures linking any two of the original data sets.

[Taxonomic composition and zoogeographical aspects of deep sea fishes (90-540m) from the Gulf of California, Mexico].

PubMed

López-Martínez, Juana; Acevedo-Cervantes, Alejandro; Herrera-Valdivia, Eloisa; Rodríguez-Romero, Jesús; Palacios-Salgado, Deivis S

2012-03-01

The Gulf of California has a high variety of ecosystems that allow different services and the fishery resources play a prominent role in its ecology, evolution and economics. Fish coastal species have been previously reported for most coastal areas, especially those species that are subject to fishing, however, little is known on the species from deep sea zones, due to sampling difficulties. We studied the deep sea fishes collected with trawl nets during three research surveys in the Gulf of California, Mexico in 2004-2005. We provide a systematic checklist and some notes on biogeographical aspects. For this, 74 fishing hauls were done, and a total of 9 898 fishes were captured, belonging to two classes, 15 orders, 35 families, 53 genera and 70 species. The best represented families in number of species were: Paralichthyidae (eight), Serranidae (six), and Scorpaenidae and Triglidae with five species each one. The typical families from deep waters were: Ophidiidae, Moridae, Lophiidae, Scorpaenidae, Triglidae, Paralichthydae, Pleuronectidae and Cynoglossidae. Size range varied from 13cm for the Splinose searobin (Bellator xenisma) to 234cm in the Pacific Cutlassfish (Trichiurus nitens). The biogeographical affinity showed that species with affinity to the East Tropical Pacific (ETP) dominated, followed by species from San Diego-Panamic, San Diego-Panamic-Peruvian-Chilean and Oregonian-Cortes provinces, respectively. A biogeographic overlap was found in the fauna, which reflects the Gulf of California's geographical position, with distribution limits of species from temperate, tropical and warm-temperature transition affinities, divisions that characterize the Gulf of California. Taxonomic status of fish with a focus on composition, location, characterization and zoogeography are fundamental to any subject of biodiversity and fisheries management actions.

[Sea star (Asteroidea) association structures on the rocky reef in the Gulf of California, Mexico].

PubMed

Reyes Bonilla, Héctor; González Azcárraga, Adriana; Rojas Sierra, Aracely

2005-12-01

Sea stars are invertebrates that play relevant roles in rocky and coral reefs: they occupy different levels in food webs and may act as top predators. There are numerous studies on taxonomy and biogeography of the class in the eastern tropical Pacific, but information about the attributes and composition of its assemblages is scant. The objectives of this study were the examination and comparison of asteroid community structure from four regions of the Gulf of California, Mexico, characterized by the presence of rocky reefs, and the search for possible associations between pairs of species. In August 2004 we visited four locations in the western gulf: Bahia de Los Angeles (29 degrees N), Santa Rosalia (27 degrees N), Loreto (26 degrees N) and La Paz (24 degrees N), and censuses sea stars using 50 m2 belt transects (N=93). Abundance and species richness was estimated, as well as diversity (H'), evenness (J') and taxonomic distinctness (delta*); then, all variables were compared among regions with analysis of variance. In addition, an ordination analysis was run looking for groups of locations with similar faunistic composition. Our results showed that Loreto Bay had the highest richness and abundance of asteroids, probably because it presents a large number of habitats and multiple food sources; these conditions seem to favor the occurrence of rare species and of detritivores. However, there were no significant interregional differences among ecological indices, nor we detected groups of locations singled out because of its species composition. Thus, community structure of sea stars in rocky areas of the Gulf of California is quite homogeneous and do not change with latitude. This is a consequence of the fact that all regions under analysis had the species Phataria unifascialis and Pharia pyramidatus as dominant in number. There were significant positive associations between three pairs of species: apparently competition is not particularly relevant to control sea

Under the Golden Gate bridge: views of the sea floor near the entrance to San Francisco Bay, California

USGS Publications Warehouse

Dartnell, Peter; Barnard, Patrick L.; Chin, John L.; Hanes, Daniel; Kvitek, Rikk G.; Iampietro, Pat J.; Gardner, James V.

2006-01-01

San Francisco Bay in Northern California is one of the largest and most altered estuaries within the United States. The sea floor within the bay as well as at its entrance is constantly changing due to strong tidal currents, aggregate mining, dredge disposal, and the creation of new land using artificial fill. Understanding this dynamic sea floor is critical for addressing local environmental issues, which include defining pollution transport pathways, deciphering tectonics, and identifying benthic habitats. Mapping commercial interests such as safe ship navigation and dredge disposal is also significantly aided by such understanding. Over the past decade, the U.S. Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), and California State University, Monterey Bay (CSUMB) in cooperation with the U.S. Army Corps of Engineers (USACOE) and the Center for Integrative Coastal Observation, Research and Education (CICORE) have partnered to map central San Francisco Bay and its entrance under the Golden Gate Bridge using multibeam echosounders. These sonar systems can continuously map to produce 100 percent coverage of the sea floor at meter-scale resolution and thus produce an unprecedented view of the floor of the bay. This poster shows views of the sea floor in west-central San Francisco Bay around Alcatraz and Angel Islands, underneath the Golden Gate Bridge, and through its entrance from the Pacific Ocean. The sea floor is portrayed as a shaded relief surface generated from the multibeam data color-coded for depth from light blues for the shallowest values to purples for the deepest. The land regions are portrayed by USGS digital orthophotographs (DOQs) overlaid on USGS digital elevation models (DEMs). The water depths have a 4x vertical exaggeration while the land areas have a 2x vertical exaggeration.

Causes of mortality in California sea otters during periods of population growth and decline

USGS Publications Warehouse

Estes, J.A.; Hatfield, B.B.; Ralls, K.; Ames, J.

2003-01-01

Elevated mortality appears to be the main reason for both sluggish growth and periods of decline in the threatened California sea otter population. We assessed causes of mortality from salvage records of 3,105 beach-cast carcasses recovered from 1968 through 1999, contrasting two periods of growth with two periods of decline. Overall, an estimated 40%-60% of the deaths were not recovered and 70% of the recovered carcasses died from unknown causes. Nonetheless, several common patterns were evident in the salvage records during the periods of population decline. These included greater percentages of (1) prime age animals (3-10 yr), (2) carcasses killed by great white shark attacks, (3) carcasses recovered in spring and summer, and (4) carcasses for which the cause of death was unknown. Neither sex composition nor the proportion of carcasses dying of infectious disease varied consistently between periods of population increase and decline. The population decline from 1976 to 1984 was likely due to incidental mortality in a set-net fishery, and the decline from 1995 to 1999 may be related to a developing live-fish fishery. Long-term trends unrelated to periods of growth and decline included a decrease in per capita pup production and mass/length ratios of adult carcasses over the 31-yr study. The generally high proportion of deaths from infectious disease suggests that this factor has contributed to the chronically sluggish growth rate of the California sea otter population.

Discriminating Characteristics of Tectonic and Human-Induced Seismicity

NASA Astrophysics Data System (ADS)

Zaliapin, I. V.; Ben-Zion, Y.

2015-12-01

We analyze statistical features of background and clustered subpopulations of earthquakes in different regions in an effort to distinguish between human-induced and natural seismicity. Analysis of "end-member" areas known to be dominated by human-induced earthquakes (the Geyser geothermal field in northern California and TauTona gold mine in South Africa) and regular tectonic activity (the San Jacinto fault zone in southern California and Coso region excluding the Coso geothermal field in eastern central California) reveals several distinguishing characteristics. Induced seismicity is shown to have (i) higher rate of background events (both absolute and relative to the total rate), (ii) faster temporal offspring decay, (iii) higher intensity of repeating events, (iv) larger proportion of small clusters, and (v) larger spatial separation between parent and offspring, compared to regular tectonic activity. These differences also successfully discriminate seismicity within the Coso and Salton Sea geothermal fields in California before and after the expansion of geothermal production during the 1980s.

Microvasculature of the California sea lion (Zalophus californianus) eye and its functional significance.

PubMed

Ninomiya, Hiroyoshi

2017-05-01

To examine the ocular circulation in California sea lions (Zalophus californianus). Eyes were obtained postmortem from three sea lions that died while in captivity. Specimens from sea lions were investigated using scanning electron microscopy (SEM) of vascular corrosion casts. The thermal characteristics of live animal eyes were measured using an infrared imaging system. The major orbital artery of the sea lion was the ophthalmic artery. The artery was remarkably thick in diameter, showed a marked convolution and formed an ophthalmic rete around the optic nerve at the posterior pole of the eyeball. The long posterior ciliary artery terminates to form a prominent inner arterial circle at the pupillary margin. The iridial arteries originated from the arterial circle showing either a crimped or somewhat coiled course, extending toward the root of the iris and formed a root supplying a large amount of blood to the iris and ciliary bodies. The venules in the conjunctiva formed a well-developed venous plexus. The vortex veins showed a dilation and constriction at the site passing through the sclera. Thermographic examination revealed that the eye showed a higher degree of thermal emission than adjacent skin areas. These characteristics suggest that the ocular vasculature might play roles in thermoregulation as well as in hemodynamics by draining a large amount of blood so that the appropriate operating temperature for the eye can be maintained in a deep and cold aquatic environment. © 2016 American College of Veterinary Ophthalmologists.

33 CFR 165.T11-304 - Safety zone; Sea World Summer Nights Fireworks; Mission Bay, San Diego, California.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety zone; Sea World Summer Nights Fireworks; Mission Bay, San Diego, California. 165.T11-304 Section 165.T11-304 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS AREA...

Relative Contributions of Geothermal Pumping and Long-Term Earthquake Rate to Seismicity at California Geothermal Fields

NASA Astrophysics Data System (ADS)

Weiser, D. A.; Jackson, D. D.

2015-12-01

In a tectonically active area, a definitive discrimination between geothermally-induced and tectonic earthquakes is difficult to achieve. We focus our study on California's 11 major geothermal fields: Amedee, Brawley, Casa Diablo, Coso, East Mesa, The Geysers, Heber, Litchfield, Salton Sea, Susanville, and Wendel. The Geysers geothermal field is the world's largest geothermal energy producer. California's Department of Oil Gas and Geothermal Resources provides field-wide monthly injection and production volumes for each of these sites, which allows us to study the relationship between geothermal pumping activities and seismicity. Since many of the geothermal fields began injecting and producing before nearby seismic stations were installed, we use smoothed seismicity since 1932 from the ANSS catalog as a proxy for tectonic earthquake rate. We examine both geothermal pumping and long-term earthquake rate as factors that may control earthquake rate. Rather than focusing only on the largest earthquake, which is essentially a random occurrence in time, we examine how M≥4 earthquake rate density (probability per unit area, time, and magnitude) varies for each field. We estimate relative contributions to the observed earthquake rate of M≥4 from both a long-term earthquake rate (Kagan and Jackson, 2010) and pumping activity. For each geothermal field, respective earthquake catalogs (NCEDC and SCSN) are complete above at least M3 during the test period (which we tailor to each site). We test the hypothesis that the observed earthquake rate at a geothermal site during the test period is a linear combination of the long-term seismicity and pumping rates. We use a grid search to determine the confidence interval of the weighting parameters.

Baja California, Mexico

NASA Technical Reports Server (NTRS)

1981-01-01

An interesting view down the axis of Baja California, Mexico (26.5N, 113.0W). At the center of the Scene is Laguna Ojo de Liebre (Bay of Whales) which is a breeding area for the Pacific Grey Whale. The Sea of Cortez, also known as the Gulf of California, is to the left and the Pacific Ocean is to the right.

Evaluating the promise and pitfalls of a potential climate change-tolerant sea urchin fishery in southern California.

PubMed

Sato, Kirk N; Powell, Jackson; Rudie, Dave; Levin, Lisa A

2018-05-01

Marine fishery stakeholders are beginning to consider and implement adaptation strategies in the face of growing consumer demand and potential deleterious climate change impacts such as ocean warming, ocean acidification, and deoxygenation. This study investigates the potential for development of a novel climate change - tolerant sea urchin fishery in southern California based on Strongylocentrotus fragilis (pink sea urchin), a deep-sea species whose peak density was found to coincide with a current trap-based spot prawn fishery ( Pandalus platyceros ) in the 200-300-m depth range. Here we outline potential criteria for a climate change - tolerant fishery by examining the distribution, life-history attributes, and marketable qualities of S. fragilis in southern California. We provide evidence of seasonality of gonad production and demonstrate that peak gonad production occurs in the winter season. S. fragilis likely spawns in the spring season as evidenced by consistent minimum gonad indices in the spring/summer seasons across 4 years of sampling (2012-2016). The resiliency of S. fragilis to predicted future increases in acidity and decreases in oxygen was supported by high species abundance, albeit reduced relative growth rate estimates at water depths (485-510 m) subject to low oxygen (11.7-16.9 µmol kg -1 ) and pH Total (<7.44), which may provide assurances to stakeholders and managers regarding the suitability of this species for commercial exploitation. Some food quality properties of the S. fragilis roe (e.g. colour, texture) were comparable with those of the commercially exploited shallow-water red sea urchin ( Mesocentrotus franciscanus ), while other qualities (e.g. 80% reduced gonad size by weight) limit the potential future marketability of S. fragilis . This case study highlights the potential future challenges and drawbacks of climate-tolerant fishery development in an attempt to inform future urchin fishery stakeholders.

Assessing Withering Syndrome Resistance in California Black Abalone: Implications for Conservation and Restoration

DTIC Science & Technology

2009-01-29

worldwide. California Sea Grant College Program UC San Diego Title: Assessing withering syndrome resistance in California black abalone : Implications...Hunter S.(2009). Assessing withering syndrome resistance in California black abalone : Implications for conservation and restoration. UC San Diego...California Sea Grant College Program. Retrieved from: http://escholarship.org/uc/item/7c39q78n Keywords: black abalone , Haliotis cracherodii, captive breeding

A new perspective on the geometry of the San Andreas Fault in southern California and its relationship to lithospheric structure

USGS Publications Warehouse

Fuis, Gary S.; Scheirer, Daniel S.; Langenheim, Victoria; Kohler, Monica D.

2012-01-01

The widely held perception that the San Andreas fault (SAF) is vertical or steeply dipping in most places in southern California may not be correct. From studies of potential‐field data, active‐source imaging, and seismicity, the dip of the SAF is significantly nonvertical in many locations. The direction of dip appears to change in a systematic way through the Transverse Ranges: moderately southwest (55°–75°) in the western bend of the SAF in the Transverse Ranges (Big Bend); vertical to steep in the Mojave Desert; and moderately northeast (37°–65°) in a region extending from San Bernardino to the Salton Sea, spanning the eastern bend of the SAF in the Transverse Ranges. The shape of the modeled SAF is crudely that of a propeller. If confirmed by further studies, the geometry of the modeled SAF would have important implications for tectonics and strong ground motions from SAF earthquakes. The SAF can be traced or projected through the crust to the north side of a well documented high‐velocity body (HVB) in the upper mantle beneath the Transverse Ranges. The north side of this HVB may be an extension of the plate boundary into the mantle, and the HVB would appear to be part of the Pacific plate.

FISH BIOLOGY AND FISHERIES ECOLOGY OF THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

POSSIBLE IMPORTANCE OF ALGAL TOXINS IN THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Full-wave multiscale anisotropy tomography in Southern California

NASA Astrophysics Data System (ADS)

Lin, Yu-Pin; Zhao, Li; Hung, Shu-Huei

2014-12-01

Understanding the spatial variation of anisotropy in the upper mantle is important for characterizing the lithospheric deformation and mantle flow dynamics. In this study, we apply a full-wave approach to image the upper-mantle anisotropy in Southern California using 5954 SKS splitting data. Three-dimensional sensitivity kernels combined with a wavelet-based model parameterization are adopted in a multiscale inversion. Spatial resolution lengths are estimated based on a statistical resolution matrix approach, showing a finest resolution length of ~25 km in regions with densely distributed stations. The anisotropic model displays structural fabric in relation to surface geologic features such as the Salton Trough, the Transverse Ranges, and the San Andreas Fault. The depth variation of anisotropy does not suggest a lithosphere-asthenosphere decoupling. At long wavelengths, the fast directions of anisotropy are aligned with the absolute plate motion inside the Pacific and North American plates.

High-resolution seismic-reflection data from offshore northern California — Bolinas to Sea Ranch

USGS Publications Warehouse

Sliter, Ray W.; Johnson, Samuel Y.; Chin, John L.; Allwardt, Parker; Beeson, Jeffrey; Triezenberg, Peter J.

2016-12-05

The U.S. Geological Survey collected high-resolution seismic-reflection data in September 2009, on survey S-8-09-NC, offshore of northern California between Bolinas and Sea Ranch.The survey area spans about 125 km of California’s coast and extends around Point Reyes. Data were collected aboard the U.S. Geological Survey R/V Parke Snavely. Cumulatively, ~1,150 km of seismic-reflection data were acquired using a SIG 2mille minisparker. Subbottom acoustic depth of penetration spanned tens to several hundred meters and varied by location and underlying sediments and rock types.This report includes maps and a navigation file of the surveyed transects, utilizing Google Earth™ software, as well as digital data files showing images of each transect in SEG-Y and JPEG formats. The images of bedrock, sediment deposits, and tectonic structure provide geologic information that is essential to hazard assessment, regional sediment management, and coastal and marine spatial planning at Federal, State and local levels. This information is also valuable for future research on the geomorphic, sedimentary, tectonic, and climatic record of central California.

Flipper stroke rate and venous oxygen levels in free-ranging California sea lions.

PubMed

Tift, Michael S; Hückstädt, Luis A; McDonald, Birgitte I; Thorson, Philip H; Ponganis, Paul J

2017-04-15

The depletion rate of the blood oxygen store, development of hypoxemia and dive capacity are dependent on the distribution and rate of blood oxygen delivery to tissues while diving. Although blood oxygen extraction by working muscle would increase the blood oxygen depletion rate in a swimming animal, there is little information on the relationship between muscle workload and blood oxygen depletion during dives. Therefore, we examined flipper stroke rate, a proxy of muscle workload, and posterior vena cava oxygen profiles in four adult female California sea lions ( Zalophus californianus ) during foraging trips at sea. Flipper stroke rate analysis revealed that sea lions minimized muscle metabolism with a stroke-glide strategy when diving, and exhibited prolonged glides during the descent of deeper dives (>100 m). During the descent phase of these deep dives, 55±21% of descent was spent gliding, with the longest glides lasting over 160 s and covering a vertical distance of 340 m. Animals also consistently glided to the surface from 15 to 25 m depth during these deeper dives. Venous hemoglobin saturation ( S O 2 ) profiles were highly variable throughout dives, with values occasionally increasing during shallow dives. The relationship between S O 2 and flipper stroke rate was weak during deeper dives, while this relationship was stronger during shallow dives. We conclude that (1) the depletion of oxygen in the posterior vena cava in deep-diving sea lions is not dependent on stroke effort, and (2) stroke-glide patterns during dives contribute to a reduction of muscle metabolic rate. © 2017. Published by The Company of Biologists Ltd.

Earth observations taken by the Expedition Seven crew

NASA Image and Video Library

2003-10-11

ISS007-E-17038 (11 October 2003) --- This view featuring a close-up of the Salton Sea was taken by an Expedition 7 crewmember onboard the International Space Station (ISS). The image provides detail of the structure of the algal bloom. These blooms continue to be a problem for the Salton Sea. They are caused by high concentrations of nutrients, especially nitrogen and phosphorous, which drain into the basin from the agricultural run-off. As the algae die and decompose, oxygen levels in the sea drop, causing fish kills and hazardous condition for other wildlife.

Reclaiming agricultural drainage water with nanofiltration membranes: Imperial Valley, California, USA

USGS Publications Warehouse

Kharaka, Y.K.; Schroeder, R.A.; Setmire, J.G.; ,

2003-01-01

We conducted pilot-scale field experiments using nanofiltration membranes to lower the salinity and remove Se, As and other toxic contaminants from saline agricultural wastewater in the Imperial Valley, California, USA. Farmlands in the desert climate (rainfall - 7.4 cm/a) of Imperial Valley cover -200,000 ha that are irrigated with water (-1.7 km3 annually) imported from the Colorado River. The salinity (-850 mg/L) and concentration of Se (-2.5 ??g/L) in the Colorado River water are high and evapotranpiration further concentrates salts in irrigation drainage water, reaching salinities of 3,000-15,000 mg/L TDS and a median Se value of -30 ??g/L. Experiments were conducted with two commercially available nanofiltration membranes, using drainage water of varying composition, and with or without the addition of organic precipitation inhibitors. Results show that these membranes selectively remove more than 95% of Se, SO4, Mo, U and DOC, and -30% of As from this wastewater. Low percentages of Cl, NO3 and HCO3, with enough cations to maintain electrical neutrality also were removed. The product water treated by these membranes comprised more than 90% of the wastewater tested. Results indicate that the treated product water from the Alamo River likely will have less than 0.2 ??g/L Se, salinity of 300-500 mg/L TDS and other chemical concentrations that meet the water quality criteria for irrigation and potable use. Because acceptability is a major issue for providing treated wastewater to urban centers, it may be prudent to use the reclaimed water for irrigation and creation of lower salinity wetlands near the Salton Sea; an equivalent volume of Colorado River water can then be diverted for the use of increasing populations of San Diego and other urban centers in southern California. Nanofiltration membranes yield greater reclaimed-water output and require lower pressure and less pretreatment, and therefore are generally more cost effective than traditional reverse

Constraints on Shallow Crustal Structure across the San Andreas Fault Zone, Coachella Valley, Southern California: Results from the Salton Seismic Imaging Project (SSIP)

NASA Astrophysics Data System (ADS)

Hernandez, A.; Persaud, P.; Bauer, K.; Stock, J. M.; Fuis, G. S.; Hole, J. A.; Goldman, M.

2015-12-01

The strong influence of basin structure and crustal heterogeneities on seismic wave propagation suggests that these factors should be included in calculations of strong ground shaking. Knowledge of the shallow subsurface is thus essential for an accurate seismic hazard estimate for the densely populated Coachella Valley, the region north of the potential M7.8 rupture near the Salton Sea. Using SSIP data, we analyzed first arrivals from nine 65-911 kg explosive shots recorded along a profile in the Coachella Valley in order to evaluate the interpretation of our 2D tomographic results and give added details on the structural complexity of the shallow crust. The line extends 37 km from the Peninsular Ranges to the Little San Bernardino Mountains crossing the major strands of the San Andreas Fault Zone. We fit traveltime curves to our picks with forward modeling ray tracing, and determined 1D P-wave velocity models for traveltime arrivals east and west of each shot, and a 2D model for the line. We also inferred the geometry of near-vertical faults from the pre-stack line migration method of Bauer et al. (2013). In general, the 1D models east of individual shots have deeper basement contacts and lower apparent velocities, ~5 km/s at 4 km depth, whereas the models west of individual shots have shallower basement and velocities up to 6 km/s at 2 km depth. Mismatches in basement depths (assuming 5-6 km/s) between individual 1D models indicate a shallowly dipping basement, deepening eastward towards the Banning Fault and shoaling abruptly farther east. An east-dipping structure in the 2D model also gives a better fit than horizontal layers. Based on high velocity zones derived from traveltimes at 9-20 km from the western end of the line, we included an offset from ~2 km to 4 km depth near the middle of the line, which significantly improved the 2D model fit. If fault-related, this offset could represent the Garnet Hill Fault if it continues southward in the subsurface.

Early Pliocene Hiatus in Sand Output by the Colorado River: Evidence From Marine Deposits in the Salton Trough, Southern California

NASA Astrophysics Data System (ADS)

Dorsey, R. J.; Bykerk-Kauffman, A.

2015-12-01

Early Pliocene deposits in the western Salton Trough preserve a high-fidelity record of sediment dispersal into the marine realm during initiation and early evolution of the Colorado River (CR). Grain-size fractionation, sediment routing, and transport dynamics of the early CR delta are recorded in sediments of the Fish Creek - Vallecito basin, which was located ~100 km south of Yuma along the transform plate boundary at 5 Ma. Early Pliocene delivery of CR sand to the basin took place in two distinct pulses: (1) deposition of sandy turbidites (Wind Caves Mbr of the Latrania Fm) in a restricted submarine canyon at Split Mt Gorge between ~5.3 and 5.1 Ma; and (2) progradation of a thick, widespread, coarsening-up deltaic sequence of marine mudstone, sandstone, and coquinas (Deguynos Fm) between ~4.8 and 4.2 Ma. Estimated flux of CR sediment during Wind Caves deposition was weak (~3-5 Mt/yr) compared to the long-term average (172±64 Mt/yr). The two pulses of CR sand input are separated by the Coyote Clay (CC, ~5.1-4.8 Ma), a regionally correlable, greenish-yellow-weathering marine claystone unit at the base of the Deguynos Fm. CC gradationally overlies Wind Caves turbidites in the area of the paleocanyon. In contrast, in the Coyote Mts 15-23 km to the south and SE, CC rests on coarse-grained locally-derived late Miocene sedimentary rocks, Alverson volcanics, and metamorphic basement rock along a regional unconformity. Identical claystone facies occur in the NW Indio Hills (restores to Yuma at the mouth of the CR at 5 Ma), and Sierra Cucapa in Mexico (~200 km south of Yuma at 5 Ma). Marine localities outside of the Wind Caves paleocanyon experienced slow to negligible sedimentation along a rugged rocky shoreline until abrupt arrival of CR-derived clay. CC accumulated in a sand-starved, pro-delta marine setting (Winker, 1987) over an inferred N-S distance of ~200 km. We therefore reject an alternate hypothesis that CC accumulated on the muddy slope of the prograding CR

Human Disturbance Influences Reproductive Success and Growth Rate in California Sea Lions (Zalophus californianus)

PubMed Central

French, Susannah S.; González-Suárez, Manuela; Young, Julie K.; Durham, Susan; Gerber, Leah R.

2011-01-01

The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations. PMID:21436887

The cost of reproduction: differential resource specialization in female and male California sea otters.

PubMed

Smith, Emma A Elliott; Newsome, Seth D; Estes, James A; Tinker, M Tim

2015-05-01

Intraspecific variation in behavior and diet can have important consequences for population and ecosystem dynamics. Here, we examine how differences in reproductive investment and spatial ecology influence individual diet specialization in male and female southern sea otters (Enhydra lutris nereis). We hypothesize that greater reproductive constraints and smaller home ranges of females lead to more pronounced intraspecific competition and increased specialization. We integrate stable carbon (δ(13)C) and nitrogen (δ(15)N) isotope analysis of sea otter vibrissae with long-term observational studies of five subpopulations in California. We define individual diet specialization as low ratios of within-individual variation (WIC) to total population niche width (TNW). We compare isotopic and observational based metrics of WIC/TNW for males and females to data on population densities, and movement patterns using both general linear and linear mixed-effects models. Consistent with our hypothesis, increasing population density is associated with increased individual diet specialization by females but not by males. Additionally, we find the amount of coastline in a sea otter's home range positively related with individual dietary variability, with increased range span resulting in weaker specialization for both males and females. We attribute our results to sex-based differences in movement, with females needing to specialize in their small ranges to maximize energy gain, and posit that the paradigm of individual prey specialization in sea otters with increased intraspecific competition may be a pattern driven largely by females. Our work highlights a potentially broader role of sex in the mechanistic pressures promoting and maintaining diet specialization.

The cost of reproduction: differential resource specialization in female and male California sea otters

USGS Publications Warehouse

Elliott Smith, Emma A.; Newsome, Seth D.; Estes, James A.; Tinker, M. Tim

2015-01-01

Intraspecific variation in behavior and diet can have important consequences for population and ecosystem dynamics. Here, we examine how differences in reproductive investment and spatial ecology influence individual diet specialization in male and female southern sea otters (Enhydra lutris nereis). We hypothesize that greater reproductive constraints and smaller home ranges of females lead to more pronounced intraspecific competition and increased specialization. We integrate stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of sea otter vibrissae with long-term observational studies of five subpopulations in California. We define individual diet specialization as low ratios of within-individual variation (WIC) to total population niche width (TNW). We compare isotopic and observational based metrics of WIC/TNW for males and females to data on population densities, and movement patterns using both general linear and linear mixed-effects models. Consistent with our hypothesis, increasing population density is associated with increased individual diet specialization by females but not by males. Additionally, we find the amount of coastline in a sea otter’s home range positively related with individual dietary variability, with increased range span resulting in weaker specialization for both males and females. We attribute our results to sex-based differences in movement, with females needing to specialize in their small ranges to maximize energy gain, and posit that the paradigm of individual prey specialization in sea otters with increased intraspecific competition may be a pattern driven largely by females. Our work highlights a potentially broader role of sex in the mechanistic pressures promoting and maintaining diet specialization.

Associations between trace elements and clinical health parameters in the North Pacific loggerhead sea turtle (Caretta caretta) from Baja California Sur, Mexico.

PubMed

Ley-Quiñónez, César Paúl; Rossi-Lafferriere, Natalia Alejandra; Espinoza-Carreon, Teresa Leticia; Hart, Catherine Edwina; Peckham, Sherwood Hoyt; Aguirre, Alfredo Alonso; Zavala-Norzagaray, Alan Alfredo

2017-04-01

This study investigated selected trace elements toxicity in sea turtles Caretta caretta population from Baja California Sur (BCS), Mexico, by analyzing associations among Zn, Se, Cu, As, Cd, Ni, Mn, Pb, and Hg with various biochemical parameters (packed cell volume, leukocytes, and selected blood parameters), and whether their concentrations could have an impact on the health status of sea turtles. Blood samples from 22 loggerhead (C. caretta) sea turtles from BCS, Mexico, were collected for trace elements on biochemistry parameter analyses. Significant associations among trace element levels and the biochemistry parameters were found: Cd vs ALP (R 2  = 0.874, p ˂ 0.001), As vs ALP (R 2  = 0.656, p ˂ 0.001), Mn vs ALP (R 2  = 0.834, p ˂ 0.001), and Ni vs LDH (R 2  = 0.587, p ˂ 0.001). This study is the first report of the biochemical parameters of the North Pacific loggerhead sea turtle (C. caretta) from Baja California Sur, Mexico, and it is the first to observe several associations with toxic and essential trace elements. Our study reinforces the usefulness of blood for the monitoring of the levels of contaminating elements and the results suggest that, based on the associations with health clinical parameters, high levels of Cd and As could be representing a risk to the North Pacific loggerhead population health.

Recent Volcanism in the Northern Gulf of California: The Effects of Thick Deltaic Sedimentation in Magmatic Differentiation

NASA Astrophysics Data System (ADS)

Martin, A.; Hurtado, J. C.; Weber, B.; Schmitt, A. K.

2016-12-01

Quaternary volcanism in the northern Gulf of California provides a unique opportunity to characterize active crustal accretion under thick deltaic sedimentation from the Colorado River. Up to 17 volcanic seamounts are identified by high-resolution bathymetry and seismic reflexion profiles, principally in the Lower Delfin and the sheared peninsular margin north of Canal de Ballenas. Samples from eight subaereal and three submarine volcanoes are distinctively composed of andesite to rhyolite, and no basaltic eruptions are yet recognized, although dolerite sills and xenoliths of microphyric gabbro are reported in geothermal wells both, in the Salton and Cerro Prieto basins and saucer shape sills in the Lower Delfin basin indicate shallow mafic intrusions. Sr-Nd isotope data indicate that parent magma derives from partial melting of the Pacific mantle indicating that continental rupture is complete in the active rift basins. However, these rocks also demonstrate evidence of assimilation (eNd 1 to 5) and thus are compositionally modified as they are transported through the thick sequence of water rich sediments. Re-melting of hydrothermally altered mafic intrusives, crystal fractionation and variable (<20%) assimilation of continental crust and sediments produce the observed compositional spectra of Quaternary to Holocene eruptions. We explore the effects of thick, poorly consolidated sediments in the ascent of basaltic magma by means of a hydrostatic model that consider the crustal density structure in the Upper Delfin basin and sediment density logs from exploration wells. The hydrostatic model predicts that basaltic magma (2.68 g/cc) stalls 1 to 1.5 km beneath the seafloor and only andesite to rhyolite magmas reach shallower levels, where they exsolve volatiles and produce volcanic eruptions. We conclude that thick deltaic deposits promote magmatic differentiation and formation of a hybrid type of new crust in narrow rift basins in the northern Gulf of California and

Earth observation taken by the Expedition 29 crew

NASA Image and Video Library

2011-11-16

ISS029-E-042846 (16 Nov. 2011) --- Parts of the U.S. and Mexico are seen in this image photographed by one of the Expedition 29 crew members from the International Space Station as it flew above the Pacific Ocean on Nov. 16, 2011. The Salton Sea is in the center of the frame, with the Gulf of Cortez, Mexico's Baja California and the Colorado River in the upper right quadrant. The Los Angeles Basin and Santa Catalina and San Clemente islands are at the bottom center edge of the image. Lake Mead and the Las Vegas area of Nevada even made it into the frame in the upper left quadrant.

Earth Observation

NASA Image and Video Library

2014-06-23

ISS040-E-017377 (23 June 2014) --- One of the Expedition 40 crew members aboard the International Space Station recorded this image showing several states in the USA and a small part of Mexico, including Baja California, on June 23, 2014. Parts of Nevada are visible in the bottom of the frame. The area in the Mojave Desert where many space shuttle missions successfully ended is visible near the scene's center. The Gulf of Cortez and several hundred miles of the Pacific coast line of Mexico and California are visible in the top portion of the photo. The heavily populated Los Angeles Basin is just above the Mojave site of shuttle landings, with the San Diego area partially obscured by the docked Russian Soyuz vehicle in the foreground. The Salton Sea is just above left center frame.

Crustal-scale tilting of the central Salton block, southern California

USGS Publications Warehouse

Dorsey, Rebecca; Langenheim, Victoria

2015-01-01

The southern San Andreas fault system (California, USA) provides an excellent natural laboratory for studying the controls on vertical crustal motions related to strike-slip deformation. Here we present geologic, geomorphic, and gravity data that provide evidence for active northeastward tilting of the Santa Rosa Mountains and southern Coachella Valley about a horizontal axis oriented parallel to the San Jacinto and San Andreas faults. The Santa Rosa fault, a strand of the San Jacinto fault zone, is a large southwest-dipping normal fault on the west flank of the Santa Rosa Mountains that displays well-developed triangular facets, narrow footwall canyons, and steep hanging-wall alluvial fans. Geologic and geomorphic data reveal ongoing footwall uplift in the southern Santa Rosa Mountains, and gravity data suggest total vertical separation of ∼5.0–6.5 km from the range crest to the base of the Clark Valley basin. The northeast side of the Santa Rosa Mountains has a gentler topographic gradient, large alluvial fans, no major active faults, and tilted inactive late Pleistocene fan surfaces that are deeply incised by modern upper fan channels. Sediments beneath the Coachella Valley thicken gradually northeast to a depth of ∼4–5 km at an abrupt boundary at the San Andreas fault. These features all record crustal-scale tilting to the northeast that likely started when the San Jacinto fault zone initiated ca. 1.2 Ma. Tilting appears to be driven by oblique shortening and loading across a northeast-dipping southern San Andreas fault, consistent with the results of a recent boundary-element modeling study.

Molecular characterization and morphology of the photosynthetic dinoflagellate Bysmatrum caponii from two solar saltons in western Korea

NASA Astrophysics Data System (ADS)

Jeong, Hae Jin; Jang, Se Hyeon; Kang, Nam Seon; Yoo, Yeong Du; Kim, Min Jeong; Lee, Kyung Ha; Yoon, Eun Young; Potvin, Éric; Hwang, Yeong Jong; Kim, Jong Im; Seong, Kyeong Ah

2012-03-01

Species belonging to the genus Bysmatrum are peridinoid, thecate, photosynthetic dinoflagellates. The plate formula of Bysmatrum spp., arranged in a Kofoidian series, is almost identical to that of Scrippsiella spp. Bysmatrum spp., which were originally classified as Scrippsiella spp., but were transferred to the genus Bysmatrum spp. because of separation of the intercalary plates 2a and 3a by plate 3'. Whether this transfer from Scrippsiella spp. to Bysmatrum spp. is reasonable should be genetically confirmed. Dinoflagellates were isolated from 2 solar saltons located in western Korea in 2009-2010 and 3 clonal cultures from Sooseong solar saltons and 2 clonal cultures from Garolim solar saltons were successfully established. All of these dinoflagellates were identified as Bysmatrum caponii based on morphology analysis by light and electron microscopy. The plates of all Korean strains of B. caponii were arranged in a Kofoidian series of Po, X, 4', 3a, 7″, 6c, 4s, 5‴, 0 (p), and 24'. When properly aligned, the ribosomal DNA (rDNA) sequences of the 3 Sooseong strains of B. caponii were identical, as were those of the 2 Garolim strains. Furthermore, the sequences of the 3 Sooseong strains were 0.01% different from those of the Garolim strains. However, the sequences of SSU rDNA of these Korean B. caponii strains were 9% different from that of Bysmatrum subsalsum and > 10% from that of any other dinoflagellate thus far reported. In the phylogenetic trees generated using SSU and LSU rDNA sequences, these Korean B. caponii strains formed a clade with B. subsalsum which was clearly divergent from the Scrippsiella clade. However, this Bysmatrum clade was phylogenetically close to the Protoperidinium and/or Peridinium clades. The results of the present study suggest that Bysmatrum spp. are markedly different genetically from Scrippsiella spp..

Comparision between crustal density and velocity variations in Southern California

USGS Publications Warehouse

Langenheim, V.E.; Hauksson, E.

2001-01-01

We predict gravity from a three-dimensional Vp model of the upper crust and compare it to the observed isostatic residual gravity field. In general this comparison shows that the isostatic residual gravity field reflects the density variations in the upper to middle crust. Both data sets show similar density variations for the upper crust in areas such as the Peninsular Ranges and the Los Angeles basin. Both show similar variations across major faults, such as the San Andreas and Garlock faults in the Mojave Desert. The difference between the two data sets in regions such as the Salton Trough, the Eastern California Shear Zone, and the eastern Ventura basin (where depth to Moho is <30 km), however, suggests high-density middle to lower crust beneath these regions. Hence the joint interpretation of these data sets improves the depth constraints of crustal density variations.

A portable FTS measurements during GOSAT and OCO-2 joint campaign in Western US 2017

NASA Astrophysics Data System (ADS)

Shiomi, K.; Kikuchi, N.; Kuze, A.; Hashimoto, M.; Suto, H.; Kataoka, F.; Kasai, K.; Arai, T.; Oshio, H.; Ohyama, H.; Morino, I.; Hori, A.; Hedelius, J.; Parker, H. A.; Roehl, C. M.; Wennberg, P. O.; Leifer, I.; Iraci, L. T.; Bruegge, C. J.; Schwandner, F. M.; Osterman, G. B.; Crisp, D.

2017-12-01

The column-average dry air mole fractions of carbon dioxide (XCO2), methane (XCH4) and carbon monoxide (XCO) were measured from the surface using direct sunlight at near-IR wavelengths. Simultaneous detection of CO is helpful to characterize CO2 source type. We measured XCO along with XCO2 and XCH4 using an upgraded portable Fourier transform spectrometer (FTS), EM27/SUN, in western US field experiments at 1) Caltech and JPL, in Pasadena, a northern Los Angeles suburb, 2) Railroad Valley (RRV), a desert playa in Nevada, and 3) Salton Sea, a terminal high-salinity lake in southern California's Imperial Valley. These measurements were conducted during the GOSAT/OCO-2 joint campaign in the early summer of 2017. Before and after US shipments, the JAXA EM27 was compared with the NIES EM27 and Tsukuba TCCON station to quantify the measurement bias and to identify any unanticipated changes. After US shipment, the JAXA EM27 was compared with the Caltech EM27 and the Caltech TCCON station with the NASA-Dryden TCCON station, which is now located at JPL for OCO-3 pre-flight test comparisons. At RRV, we obtained not only the EM27 data but also atmospheric profile of pressure, temperature and humidity by radiosonde and aerosol optical thickness (AOT) by Microtops. Then, we deployed the EM27 on the south side of the Salton Sea, where agriculture, active volcanism and geothermal power plants might produce CO2 and CH4 as sources. A large CO enhancement originating from wildfires was serendipitously measured in conjunction with a large AOT measured by the Microtops. The JAXA EM27 measurements at Pasadena, RRV and Salton Sea were taken in conjunction with GOSAT and OCO-2 overpass targets and are being used to assess the value of the EM27 as a portable transfer standard for validating space based measurements of greenhouse gases.

Age and paleoenvironment of the imperial formation near San Gorgonio Pass, Southern California

USGS Publications Warehouse

McDougall, K.; Poore, R.Z.; Matti, J.

1999-01-01

Microfossiliferous marine sediments of the Imperial Formation exposed in the Whitewater and Cabazon areas, near San Gorgonio Pass, southern California, are late Miocene in age and were deposited at intertidal to outer neritic depths, and possibly upper bathyal depths. A late Miocene age of 7.4 to >6.04 Ma is based on the ranges of age-diagnostic benthic foraminifers (Cassidulina delicata and Uvigerina peregrina), planktic foraminifers (Globigerinoides obliquus, G. extremus, and Globigerina nepenthes; zones N17-N19), and calcareous nannoplankton (Discoaster brouweri, D. aff. D. surculus, Reticulofenestra pseudoumbilicata, Sphenolithus abies, and S. neoabies; zones CN9a-CN11) coupled with published K/Ar dates from the underlying Coachella Formation (10.1 ?? 1.2 Ma; Peterson, 1975) and overlying Painted Hill Formation (6.04 ?? 0.18 and 5.94 ?? 0.18 Ma; J. L. Morton in Matti and others, 1985 and Matti and Morton, 1993). Paleoecologic considerations (sea-level fluctuations and paleotemperature) restrict the age of the Imperial Formation to 6.5 through 6.3 Ma. Benthic foraminiferal assemblages indicate that the Imperial Formation in the Whitewater and Cabazon sections accumulated at inner neritic to outer neritic (0-152 m) and possibly upper bathyal (152-244 m) depths. Shallowing to inner neritic depths occurred as the upper part of the section was deposited. This sea-level fluctuation corresponds to a global highstand at 6.3 Ma (Haq and others, 1987). Planktic foraminifers suggest an increase in surface-water temperatures upsection. A similar increase in paleotemperatures is interpreted for the North Pacific from 6.5 to 6.3 Ma (warm interval W10 of Barron and Keller, 1983). Environmental contrasts between the Whitewater and Cabazon sections of the Imperial Formation provide evidence for right-lateral displacements on the Banning fault, a late Miocene strand of the San Andreas fault system. The Cabazon section lies south of the Banning fault, and has been displaced west

Year 3 Summary Report: Baseline Selenium Monitoring of Agricultural Drains Operated by the Imperial Irrigation District in the Salton Sea Basin

USGS Publications Warehouse

Saiki, Michael K.; Martin, Barbara A.; May, Thomas W.

2008-01-01

This report summarizes findings from the third year of a 4-year-long field investigation to document selected baseline environmental conditions in 29 agricultural drains and ponds operated by the Imperial Irrigation District along the southern border of the Salton Sea. Routine water quality and fish species were measured at roughly quarterly intervals from April 2007 to January 2008. The water quality measurements included total suspended solids and total (particulate plus dissolved) selenium. In addition, during April and October 2007, water samples were collected from seven intensively monitored drains for measurement of particulate and dissolved selenium, including inorganic and organic fractions. In addition, sediment, aquatic food chain matrices (particulate organic detritus, filamentous algae, net plankton, and midge [chironomid] larvae), and two fish species (western mosquitofish, Gambusia affinis; and sailfin molly, Poecilia latipinna) were sampled from the seven drains for measurement of total selenium concentrations. The mosquitofish and mollies were intended to serve as surrogates for desert pupfish (Cyprinodon macularius), an endangered species that we were not permitted to take for selenium determinations. Water quality values were typical of surface waters in a hot desert climate. A few drains exhibited brackish, near anoxic conditions especially during the summer and fall when water temperatures occasionally exceeded 30 degrees C. In general, total selenium concentrations in water varied directly with conductivity and inversely with pH. Although desert pupfish were found in several drains, sometimes in relatively high numbers, the fish faunas of most drains and ponds were dominated by nonnative species, especially red shiner (Cyprinella lutrensis), mosquitofish, and mollies. Dissolved selenium in water samples from the seven intensively monitored drains ranged from 0.700 to 24.1 ug/L, with selenate as the major constituent in all samples. Selenium

Weak Polygyny in California Sea Lions and the Potential for Alternative Mating Tactics

PubMed Central

Flatz, Ramona; González-Suárez, Manuela; Young, Julie K.; Hernández-Camacho, Claudia J.; Immel, Aaron J.; Gerber, Leah R.

2012-01-01

Female aggregation and male territoriality are considered to be hallmarks of polygynous mating systems. The development of genetic parentage assignment has called into question the accuracy of behavioral traits in predicting true mating systems. In this study we use 14 microsatellite markers to explore the mating system of one of the most behaviorally polygynous species, the California sea lion (Zalophus californianus). We sampled a total of 158 female-pup pairs and 99 territorial males across two breeding rookeries (San Jorge and Los Islotes) in the Gulf of California, Mexico. Fathers could be identified for 30% of pups sampled at San Jorge across three breeding seasons and 15% of sampled pups at Los Islotes across two breeding seasons. Analysis of paternal relatedness between the pups for which no fathers were identified (sampled over four breeding seasons at San Jorge and two at Los Islotes) revealed that few pups were likely to share a father. Thirty-one percent of the sampled males on San Jorge and 15% of the sampled males on Los Islotes were assigned at least one paternity. With one exception, no male was identified as the father of more than two pups. Furthermore, at Los Islotes rookery there were significantly fewer pups assigned paternity than expected given the pool of sampled males (p<0.0001). Overall, we found considerably lower variation in male reproductive success than expected in a species that exhibits behavior associated with strongly polygynous mating. Low variation in male reproductive success may result from heightened mobility among receptive females in the Gulf of California, which reduces the ability of males to monopolize groups of females. Our results raise important questions regarding the adaptive role of territoriality and the potential for alternative mating tactics in this species. PMID:22432039

Factors influencing the at-sea distribution of Cassin's Auklets (Ptychoramphus aleuticus) that breed in the Channel Islands, California

USGS Publications Warehouse

Adams, Josh; Takekawa, John Y.; Carter, Harry R.; Yee, Julie L.

2010-01-01

We used radiotelemetry to evaluate at-sea habitat use by Cassin's Auklets (Ptychoramphus aleuticus) that bred at Prince Island, off southern California, from 1999 through 2001. We used logistic regression to compare paired radiotelemetry (presence) with random (pseudo-absence) location-associated habitat variables derived from (1) satellite remote-sensing of sea surface temperature and chlorophyll-a concentration and (2) bathymetry. Compared with random locations within their foraging area and after controlling for distance to colony, odds ratios indicated that Cassin's Auklets with dependent young occurred in relatively shallower, warmer, and chlorophyll-rich water associated with chlorophyll fronts near the insular shelf break. These oceanographic features characterize habitats that support key euphausiid prey (e.g., Thysanoessa spinifera) and also other krill predators. Radiotelemetry combined with satellite remote-sensing of the ocean provides an alternative to vessel-based surveys for evaluating seabird foraging habitats. In the absence of information on the actual distribution, abundance, and, hence, availability of Zooplankton prey for seabirds, environmental factors can serve as proxies to help elucidate distributional patterns of seabirds at sea.

Sea-surface temperature gradients across blue whale and sea turtle foraging trajectories off the Baja California Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Etnoyer, Peter; Canny, David; Mate, Bruce R.; Morgan, Lance E.; Ortega-Ortiz, Joel G.; Nichols, Wallace J.

2006-02-01

Sea-surface temperature (SST) fronts are integral to pelagic ecology in the North Pacific Ocean, so it is necessary to understand their character and distribution, and the way these features influence the behavior of endangered and highly migratory species. Here, telemetry data from sixteen satellite-tagged blue whales ( Balaenoptera musculus) and sea turtles ( Caretta caretta, Chelonia mydas, and Lepidochelys olivacea) are employed to characterize 'biologically relevant' SST fronts off Baja California Sur. High residence times are used to identify presumed foraging areas, and SST gradients are calculated across advanced very high resolution radiometer (AVHRR) images of these regions. The resulting values are compared to classic definitions of SST fronts in the oceanographic literature. We find subtle changes in surface temperature (between 0.01 and 0.10 °C/km) across the foraging trajectories, near the lowest end of the oceanographic scale (between 0.03 and 0.3 °C/km), suggesting that edge-detection algorithms using gradient thresholds >0.10 °C/km may overlook pelagic habitats in tropical waters. We use this information to sensitize our edge-detection algorithm, and to identify persistent concentrations of subtle SST fronts in the Northeast Pacific Ocean between 2002 and 2004. The lower-gradient threshold increases the number of fronts detected, revealing more potential habitats in different places than we find with a higher-gradient threshold. This is the expected result, but it confirms that pelagic habitat can be overlooked, and that the temperature gradient parameter is an important one.

Multiple Stressors at the Land-Sea Interface: Cyanotoxins at the Land-Sea Interface in the Southern California Bight.

PubMed

Tatters, Avery O; Howard, Meredith D A; Nagoda, Carey; Busse, Lilian; Gellene, Alyssa G; Caron, David A

2017-03-09

Blooms of toxic cyanobacteria in freshwater ecosystems have received considerable attention in recent years, but their occurrence and potential importance at the land-sea interface has not been widely recognized. Here we present the results of a survey of discrete samples conducted in more than fifty brackish water sites along the coastline of southern California. Our objectives were to characterize cyanobacterial community composition and determine if specific groups of cyanotoxins (anatoxins, cylindrospermopsins, microcystins, nodularins, and saxitoxins) were present. We report the identification of numerous potentially harmful taxa and the co-occurrence of multiple toxins, previously undocumented, at several locations. Our findings reveal a potential health concern based on the range of organisms present and the widespread prevalence of recognized toxic compounds. Our results raise concerns for recreation, harvesting of finfish and shellfish, and wildlife and desalination operations, highlighting the need for assessments and implementation of monitoring programs. Such programs appear to be particularly necessary in regions susceptible to urban influence.

Multiple Stressors at the Land-Sea Interface: Cyanotoxins at the Land-Sea Interface in the Southern California Bight

PubMed Central

Tatters, Avery O.; Howard, Meredith D.A.; Nagoda, Carey; Busse, Lilian; Gellene, Alyssa G.; Caron, David A.

2017-01-01

Blooms of toxic cyanobacteria in freshwater ecosystems have received considerable attention in recent years, but their occurrence and potential importance at the land-sea interface has not been widely recognized. Here we present the results of a survey of discrete samples conducted in more than fifty brackish water sites along the coastline of southern California. Our objectives were to characterize cyanobacterial community composition and determine if specific groups of cyanotoxins (anatoxins, cylindrospermopsins, microcystins, nodularins, and saxitoxins) were present. We report the identification of numerous potentially harmful taxa and the co-occurrence of multiple toxins, previously undocumented, at several locations. Our findings reveal a potential health concern based on the range of organisms present and the widespread prevalence of recognized toxic compounds. Our results raise concerns for recreation, harvesting of finfish and shellfish, and wildlife and desalination operations, highlighting the need for assessments and implementation of monitoring programs. Such programs appear to be particularly necessary in regions susceptible to urban influence. PMID:28282935

CHEMICAL EVOLUTION OF THE SALTON SEA, CALIFORNIA: NUTRIENT AND SELENIUM DYNAMICS. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Sea Floor off San Diego, California

USGS Publications Warehouse

Dartnell, Peter; Gibbons, Helen

2009-01-01

Ocean-floor image generated from multibeam-bathymetry data acquired by the U.S. Geological Survey (USGS); Woods Hole Oceanographic Institution; Scripps Institution of Oceanography; California State University, Monterey Bay; and Fugro Pelagos. To learn more, visit http://pubs.usgs.gov/sim/2007/2959/.

Predicting Trophic Interactions and Habitat Utilization in the California Current Ecosystem

DTIC Science & Technology

2014-09-30

on trophic interactions affecting habitat utilization and foraging patterns of California sea lions (CSL) in the California Current Large Marine...middle (sardine and anchovy) and higher (sea lions ) trophic level species. To this end, our numerical experiments are designed to isolate patterns of...NEMURO) embedded in a regional ocean circulation model (ROMS), and both coupled with a multi- species individual-based model (IBM) for forage fish

Using stable isotopes to investigate individual diet specialization in California sea otters (Enhydra lutris nereis)

USGS Publications Warehouse

Newsome, S.D.; Tinker, M.T.; Monson, Daniel H.; Oftedal, O.T.; Ralls, K.; Staedler, M.M.; Fogel, M.L.; Estes, J.A.

2009-01-01

Differences in diet composition among conspecifics (dietary specialization) have been documented across a broad range of taxonomic groups and habitats, and such variation at the individual level is increasingly recognized as an important component of diversity in trophic interactions. Accurate identification of individual dietary specialization, however, requires longitudinal dietary records that are labor-intensive and cost-prohibitive to obtain for many species. Here we explore the use of stable isotopes (δ13C and δ15N) as a promising technique for detecting and quantifying patterns of individual dietary specialization. Southern sea otters (Enhydra lutris nereis) offer a unique opportunity for testing this approach because (1) they consume a wide variety of prey that span multiple trophic levels, habitats, and ecologically defined functional groups; and (2) individual diet specialization can be validated with existing observational data. We analyzed the isotopic composition of sea otter vibrissae (n = 31) in order to characterize inter- and intra-individual variation in sea otter diets at Monterey Bay, California, USA. At the population level, sea otters showed substantial variation in both δ13C and δ15N values, occupying nearly all of the “isotopic space” created by the diversity of isotopic signatures of potential prey taxa. Most of the variation in sea otter vibrissae was accounted for by differences between individuals, with much less contributed by within-individual variation. A majority of sea otters (∼80%) showed relatively little temporal variability in isotopic composition, suggesting that the proportional composition of most individuals' diets is relatively constant over time; a few individuals (∼20%) exhibited a high degree of intra-vibrissa isotopic variability, suggesting seasonal shifts in diet composition. These results and our interpretation of them were supported by long-term observational data on the diets of radio-tagged sea otters

Integrated Climate Change Impacts Assessment in California

NASA Astrophysics Data System (ADS)

Cayan, D. R.; Franco, G.; Meyer, R.; Anderson, M.; Bromirski, P. D.

2014-12-01

This paper summarizes lessons learned from an ongoing series of climate change assessments for California, conducted by the scientific community and State and local agencies. A series of three Assessments have considered vulnerability and adaptation issues for both managed and natural systems. California's vulnerability is many faceted, arising because of an exceptionally drought prone climate, open coast and large estuary exposure to sea level rise, sensitive ecosystems and complex human footprint and economy. Key elements of the assessments have been a common set of climate and sea-level rise scenarios, based upon IPCC GCM simulations. Regionalized and localized output from GCM projections was provided to research teams investigating water supply, agriculture, coastal resources, ecosystem services, forestry, public health, and energy demand and hydropower generation. The assessment results are helping to investigate the broad range of uncertainty that is inherent in climate projections, and users are becoming better equipped to process an envelope of potential climate and impacts. Some projections suggest that without changes in California's present fresh-water delivery system, serious water shortages would take place, but that technical solutions are possible. Under a warmer climate, wildfire vulnerability is heightened markedly in some areas--estimated increases in burned area by the end of the 21st Century exceed 100% of the historical area burned in much of the forested areas of Northern California Along California coast and estuaries, projected rise in mean sea level will accelerate flooding occurrences, prompting the need for better education and preparedness. Many policymakers and agency personnel in California are factoring in results from the assessments and recognize the need for a sustained assessment process. An ongoing challenge, of course, is to achieve more engagement with a broader community of decision makers, and notably with the private sector.

MANAGEMENT OF ACUTE RENAL FAILURE WITH DELAYED HYPERCALCEMIA SECONDARY TO SARCOCYSTIS NEURONA-INDUCED MYOSITIS AND RHABDOMYOLYSIS IN A CALIFORNIA SEA LION (ZALOPHUS CALIFORNIANUS).

PubMed

Alexander, Amy B; Hanley, Christopher S; Duncan, Mary C; Ulmer, Kyle; Padilla, Luis R

2015-09-01

A 3-yr-old captive-born California sea lion (Zalophus californianus) developed Sarcocystis neurona-induced myositis and rhabdomyolysis that led to acute renal failure. The sea lion was successfully managed with fluid therapy, antiprotozoals, antibiotics, anti-inflammatories, antiemetics, gastroprotectants, and diuretics, but developed severe delayed hypercalcemia, a syndrome identified in humans after traumatic or exertion-induced rhabdomyolysis. Treatment with calcitonin was added to the management, and the individual recovered fully. The case emphasizes that animals with rhabdomyolysis-induced renal failure risk developing delayed hypercalcemia, which may be life threatening, and calcium levels should be closely monitored past the resolution of renal failure.

Mapping Diffuse Seismicity Using Empirical Matched Field Processing Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, J; Templeton, D C; Harris, D B

The objective of this project is to detect and locate more microearthquakes using the empirical matched field processing (MFP) method than can be detected using only conventional earthquake detection techniques. We propose that empirical MFP can complement existing catalogs and techniques. We test our method on continuous seismic data collected at the Salton Sea Geothermal Field during November 2009 and January 2010. In the Southern California Earthquake Data Center (SCEDC) earthquake catalog, 619 events were identified in our study area during this time frame and our MFP technique identified 1094 events. Therefore, we believe that the empirical MFP method combinedmore » with conventional methods significantly improves the network detection ability in an efficient matter.« less

Development and validation of a quantitative PCR for rapid and specific detection of California sea lion adenovirus 1 and prevalence in wild and managed populations.

PubMed

Cortés-Hinojosa, Galaxia; Gulland, Frances M D; Goldstein, Tracey; Venn-Watson, Stephanie; Rivera, Rebecca; Archer, Linda L; Waltzek, Thomas B; Gray, Gregory C; Wellehan, James F X

2017-03-01

California sea lion adenovirus 1 (CSLAdV-1) has been associated with hepatitis and enteritis in several wild and captive populations of diverse pinniped species. Currently available tests have been limited to pan-adenoviral polymerase chain reaction (PCR) followed by sequencing. We present the development of a quantitative probe-hybridization PCR (qPCR) assay for rapid, sensitive, and specific detection of this virus in California sea lions ( Zalophus californianus) and other pinnipeds. This assay did not amplify other mammalian adenoviruses and is able to detect consistently down to 10 viral copies per well. Compared with the gold standard conventional pan-adenovirus PCR/sequencing assay, diagnostic sensitivity and specificity of 100% and 88.2% were found, respectively. The lower diagnostic specificity of this qPCR assay may be the result of the lower limit of detection of this assay compared with the gold standard rather than the result of detection of true false-positives.

Inferred Rheology and Petrology of Southern California and Northwest Mexico Mantle from Postseismic Deformation following the 2010 El Mayor-Cucapah Earthquake

NASA Astrophysics Data System (ADS)

Freed, A. M.; Dickinson, H.; Huang, M. H.; Fielding, E. J.; Burgmann, R.; Andronicos, C.

2015-12-01

The Mw 7.2 El Mayor-Cucapah (EMC) earthquake ruptured a ~120 km long series of faults striking northwest from the Gulf of California to the Sierra Cucapah. Five years after the EMC event, a dense network of GPS stations in southern California and a sparse array of sites installed after the earthquake in northern Mexico measure ongoing surface deformation as coseismic stresses relax. We use 3D finite element models of seismically inferred crustal and mantle structure with earthquake slip constrained by GPS, InSAR range change and SAR and SPOT image sub-pixel offset measurements to infer the rheologic structure of the region. Model complexity, including 3D Moho structure and distinct geologic regions such as the Peninsular Ranges and Salton Trough, enable us to explore vertical and lateral heterogeneities of crustal and mantle rheology. We find that postseismic displacements can be explained by relaxation of a laterally varying, stratified rheologic structure controlled by temperature and crustal thickness. In the Salton Trough region, particularly large postseismic displacements require a relatively weak mantle column that weakens with depth, consistent with a strong but thin (22 km thick) crust and high regional temperatures. In contrast, beneath the neighboring Peninsular Ranges a strong, thick (up to 35 km) crust and cooler temperatures lead to a rheologically stronger mantle column. Thus, we find that the inferred rheologic structure corresponds with observed seismic structure and thermal variations. Significant afterslip is not required to explain postseismic displacements, but cannot be ruled out. Combined with isochemical phase diagrams, our results enable us to go beyond rheologic structure and infer some basic properties about the regional mantle, including composition, water content, and the degree of partial melting.

32. Historic American Buildings Survey From California State Library Sacramento, ...

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

32. Historic American Buildings Survey From California State Library Sacramento, California Original: Re-photo: February 1940 DETAIL OF ENTRANCE (East Elevation) - Mission San Carlos Borromeo, Rio Road & Lausen Drive, Carmel-by-the-Sea, Monterey County, CA

6. Historic American Buildings Survey From California State Library Sacramento, ...

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

6. Historic American Buildings Survey From California State Library Sacramento, California Original: Ante 1860 Re-photo: February 1940 VIEW FROM SOUTHEAST - Mission San Carlos Borromeo, Rio Road & Lausen Drive, Carmel-by-the-Sea, Monterey County, CA

Tropopause Pressure May Explain California Droughts and Wet Period

NASA Astrophysics Data System (ADS)

Mazdiyasni, O.; AghaKouchak, A.

2017-12-01

Sea surface temperatures and teleconnection patterns such as El Nino/La Nina are considered the main culprits behind major California droughts. However, the underlying relationship between sea surface temperatures (SSTs) and precipitation anomalies is relatively weak. In 2015-2016 the most extreme El Nino did not lead to a wet season as expected, which triggered a series of studies on this topic. Here we show that tropopause level pressure in a region in the northeastern Pacific Ocean (dubbed the PARS-NEP region) plays a major role in whether California will experience a wet or dry year and often dominates the role of SST-based teleconnections. Our results indicate that pressure in the PARS-NEP region Granger-Causes precipitation in California during the wet season. We show that when pressure in the PARS-NEP region is in the lower (upper) tertile, 85% of wet seasons across California have a positive (negative) precipitation anomaly. The observed relationship between PARS-NEP and California precipitation is stronger than all the commonly used SST-based climatic indictors frequently used for understanding causes of droughts.

33. Historic American Buildings Survey From California State Library Sacramento, ...

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

33. Historic American Buildings Survey From California State Library Sacramento, California Original: 1860's Re-photo: February 1940 INTERIOR OF CHURCH BEFORE RESTORATION - Mission San Carlos Borromeo, Rio Road & Lausen Drive, Carmel-by-the-Sea, Monterey County, CA

At-sea distribution of radio-marked Ashy Storm-Petrels Oceanodroma homochroa captured on the California Channel Islands

USGS Publications Warehouse

Adams, J.; Takekawa, John Y.

2008-01-01

Small, rare and wide-ranging pelagic birds are difficult to locate and observe at sea; little is therefore known regarding individual movements and habitat affinities among many of the world's storm-petrels (Family Hydrobatidae). We re-located 57 of 70 radio-marked Ashy Storm-Petrels Oceanodroma homochroa captured at three colonies in the California Channel Islands: Scorpion Rocks (2004, 2005), Santa Barbara Island (2004) and Prince Island (2005). Between 23 July and 22 September 2004, and 5 July and 4 August 2005, we flew 29 telemetry surveys, covered more than 65 000 km2 (2004) and 43 000 km2 (2005) of open ocean from San Nicolas Island north to the Farallon Islands and obtained 215 locations from 57 storm-petrels at sea. In both years, radio-marked storm-petrels were aggregated over the continental slope from Point Conception to Point Buchon, within the western Santa Barbara Channel, and over the Santa Cruz Basin between Santa Cruz, San Nicolas and Santa Barbara islands. Individuals captured in the Channel Islands ranged more than 600 km and were located as far north as Gulf of the Farallones National Marine Sanctuary. This is the first study to use radiotelemetry to determine the at-sea distribution and movements for any storm-petrel species.

Underwater audiogram of the California sea lion by the conditioned vocalization technique1

PubMed Central

Schusterman, Ronald J.; Balliet, Richard F.; Nixon, James

1972-01-01

Conditioning techniques were developed demonstrating that pure tone frequencies under water can exert nearly perfect control over the underwater click vocalizations of the California sea lion (Zalophus californianus). Conditioned vocalizations proved to be a reliable way of obtaining underwater sound detection thresholds in Zalophus at 13 different frequencies, covering a frequency range of 250 to 64,000 Hz. The audiogram generated by these threshold measurements suggests that under water, the range of maximal sensitivity for Zalophus lies between one and 28 kHz with best sensitivity at 16 kHz. Between 28 and 36 kHz there is a loss in sensitivity of 60 dB/octave. However, with relatively intense acoustic signals (> 38 dB re 1 μb underwater), Zalophus will respond to frequencies at least as high as 192 kHz. These results are compared with the underwater hearing of other marine mammals. ImagesFig. 1. PMID:5033891

A New Perspective on the Foraging Ecology of Apex Predators in the California Current: Results from a Fully Coupled Ecosystem Model

NASA Astrophysics Data System (ADS)

Fiechter, J.; Huckstadt, L. A.; Rose, K.; Costa, D. P.; Curchitser, E. N.; Hedstrom, K.; Edwards, C. A.; Moore, A. M.

2016-02-01

Results from a fully coupled end-to-end ecosystem model for the California Current Large Marine Ecosystem are used to describe the impact of environmental variability on the foraging ecology of its most abundant apex predator, California sea lions (Zalophus californianus). The ecosystem model consists of a biogeochemical submodel embedded in a regional ocean circulation submodel, and both coupled with a multi-species individual-based submodel for forage fish (sardine and anchovy) and California sea lions. For sea lions, bioenergetics and behavioral attributes are specified using available TOPP (Tagging Of Pacific Predators) data on their foraging patterns and diet in the California Current. Sardine and anchovy are explicitly included in the model as they represent important prey sources for California sea lions and exhibit significant interannual and decadal variability in population abundances. Output from a 20-year run (1989-2008) of the model demonstrates how different physical and biological processes control habitat utilization and foraging success of California sea lions on interannual time scales. A principal component analysis of sea lion foraging patterns indicates that the first mode of variability is alongshore and tied to sardine availability, while the second mode is cross-shore and associated with coastal upwelling intensity (a behavior consistent with male sea lion tracking data collected in 2004 vs. 2005). The results also illustrate how variability in environmental conditions and forage fish distribution affects sea lions feeding success. While specifically focusing on the foraging ecology of sea lions, our modeling framework has the ability to provide new and unique perspectives on trophic interactions in the California Current, or other regions where similar end-to-end ecosystem models may be implemented.

Epidemiology and potential land-sea transfer of enteric bacteria from terrestrial to marine species in the Monterey Bay Region of California.

PubMed

Oates, Stori C; Miller, Melissa A; Byrne, Barbara A; Chouicha, Nadira; Hardin, Dane; Jessup, David; Dominik, Clare; Roug, Annette; Schriewer, Alexander; Jang, Spencer S; Miller, Woutrina A

2012-07-01

Marine mammals are at risk for infection by fecal-associated zoonotic pathogens when they swim and feed in polluted nearshore marine waters. Because of their tendency to consume 25-30% of their body weight per day in coastal filter-feeding invertebrates, southern sea otters (Enhydra lutris nereis) can act as sentinels of marine ecosystem health in California. Feces from domestic and wildlife species were tested to determine prevalence, potential virulence, and diversity of selected opportunistic enteric bacterial pathogens in the Monterey Bay region. We hypothesized that if sea otters are sentinels of coastal health, and fecal pollution flows from land to sea, then sea otters and terrestrial animals might share the same enteric bacterial species and strains. Twenty-eight percent of fecal samples tested during 2007-2010 were positive for one or more potential pathogens. Campylobacter spp. were isolated most frequently, with an overall prevalence of 11%, followed by Vibrio cholerae (9%), Salmonella spp. (6%), V. parahaemolyticus (5%), and V. alginolyticus (3%). Sea otters were found positive for all target bacteria, exhibiting similar prevalences for Campylobacter and Salmonella spp. but greater prevalences for Vibrio spp. when compared to terrestrial animals. Fifteen Salmonella serotypes were detected, 11 of which were isolated from opossums. This is the first report of sea otter infection by S. enterica Heidelberg, a serotype also associated with human clinical disease. Similar strains of S. enterica Typhimurium were identified in otters, opossums, and gulls, suggesting the possibility of land-sea transfer of enteric bacterial pathogens from terrestrial sources to sea otters.

Triggered surface slips in the Salton Trough associated with the 1999 Hector Mine, California, earthquake

USGS Publications Warehouse

Rymer, M.J.; Boatwright, J.; Seekins, L.C.; Yule, J.D.; Liu, J.

2002-01-01

Surface fracturing occurred along the southern San Andreas, Superstition Hills, and Imperial faults in association with the 16 October 1999 (Mw 7.1) Hector Mine earthquake, making this at least the eighth time in the past 31 years that a regional earthquake has triggered slip along faults in the Salton Trough. Fractures associated with the event formed discontinuous breaks over a 39-km-long stretch of the San Andreas fault, from the Mecca Hills southeastward to Salt Creek and Durmid Hill, a distance from the epicenter of 107 to 139 km. Sense of slip was right lateral; only locally was there a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 13 mm. Maximum slip values in 1999 and earlier triggered slips are most common in the central Mecca Hills. Field evidence indicates a transient opening as the Hector Mine seismic waves passed the southern San Andreas fault. Comparison of nearby strong-motion records indicates several periods of relative opening with passage of the Hector Mine seismic wave-a similar process may have contributed to the field evidence of a transient opening. Slip on the Superstition Hills fault extended at least 9 km, at a distance from the Hector Mine epicenter of about 188 to 196 km. This length of slip is a minimum value, because we saw fresh surface breakage extending farther northwest than our measurement sites. Sense of slip was right lateral; locally there was a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 18 mm, with the largest amounts found distributed (or skewed) away from the Hector Mine earthquake source. Slip triggered on the Superstition Hills fault commonly is skewed away from the earthquake source, most notably in 1968, 1979, and 1999. Surface slip on the Imperial fault and within the Imperial Valley extended about 22 km, representing a distance from the Hector Mine epicenter of about 204 to 226 km. Sense of slip dominantly was right lateral; the right-lateral component of slip

Seasonal prevalence and intensity of hookworms (Uncinaria spp.) in California sea lion (Zalophus californianus) pups born in 2002 on San Miguel Island, California.

PubMed

Lyons, E T; Delong, R L; Spraker, T R; Melin, S R; Laake, J L; Tolliver, S C

2005-05-01

Intestines of California sea lion (Zalophus californianus) pups (n= 204), born in 2002 on San Miguel Island, California, were examined for hookworms (Uncinaria spp.) as part of a seasonal mortality study from June through December 2002 and January 2003. The investigation was planned to coincide with most of the previously established hookworm infection period of the pups. Prevalence of hookworms in dead pups was 100% for each month of the study. The geometric mean intensity of infections per month was: 94.03 (n=30) for June, 629.09 (n=50) for July, 319.90 (n=31) for August, 159.90 (n=30) for October, 109.03 (n=30) for November, 37.84 (n=24) for December 2002 and 11.05 (n=9) for January 2003. In addition to the temporal pattern, the infection intensity was higher for pups in good condition and for male pups. An inter-year comparison of hookworm counts from dead pups collected in July of 1996, 2000, and 2002 also demonstrated higher intensity in pups in better condition but sex-differences in intensity were inconsistent across years. The inter-year comparison also demonstrated higher intensities in dead pups collected from portions of the rookery with sandy substrate versus rocky substrate. No annual differences in intensity were found after adjusting for substrate and condition.

Atypical Red Blood Cells Are Prevalent in California Sea Lion Pups Born during Anomalous Sea Surface Temperature Events.

PubMed

Flores-Morán, Adriana; Banuet-Martínez, Marina; Elorriaga-Verplancken, Fernando R; García-Ortuño, Luis Enrique; Sandoval-Sierra, Julieta; Acevedo-Whitehouse, Karina

To date, there is limited knowledge of the effects that abnormal sea surface temperature (SST) can have on the physiology of neonate pinnipeds. However, maternal nutritional deficiencies driven by alimentary restrictions would expectedly impact pinniped development and fitness, as an adequate supply of nutrients is essential for growth and proper functioning of all body systems, including red blood cell synthesis and clearance. Here, we investigated red blood cell morphology of California sea lion (CSL) pups from the San Benito Archipelago born during the 2014 and 2015 anomalously high SST events recorded in the northeastern Pacific Ocean. We examined whether atypical erythrocyte morphologies were more common in 2015, when the high SST event was more pronounced, and whether the stable isotope signature of pup fur, as an indicator of maternal feeding strategies, accounted for the number of atypical cells. Various atypical erythrocyte morphologies were more prevalent and more abundant than reference values. Evidence of iron deficiency was found in both years, and only pups born in 2014 showed evidence of active erythropoiesis. Microcytes and reticulocytes were more common in pups with higher isotopic δ 13 C and lower δ 15 N values, suggesting a probable relationship between maternal feeding strategies and the effect of climatic anomalies on red blood cell physiology of their pups. As developing pinnipeds require increased oxygen storage capacity for diving and foraging, the presence of atypical erythrocytes could be relevant to CSL pup fitness if the underlying cause is not reverted. This study is a first step to explore the effects that climatic alterations in the marine environment can have on the blood physiology of developing individuals.

Comparison of trace element concentrations in livers of diseased, emaciated and non-diseased southern sea otters from the California coast

USGS Publications Warehouse

Kannan, K.; Agusa, T.; Perrotta, E.; Thomas, N.J.; Tanabe, S.

2006-01-01

Infectious diseases have been implicated as a cause of high rates of adult mortality in southern sea otters. Exposure to environmental contaminants can compromise the immuno-competence of animals, predisposing them to infectious diseases. In addition to organic pollutants, certain trace elements can modulate the immune system in marine mammals. Nevertheless, reports of occurrence of trace elements, including toxic heavy metals, in sea otters are not available. In this study, concentrations of 20 trace elements (V, Cr, Mn, Co, Cu, Zn, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, Pb, and Bi) were measured in livers of southern sea otters found dead along the central California coast (n = 80) from 1992 to 2002. Hepatic concentrations of trace elements were compared among sea otters that died from infectious diseases (n = 27), those that died from non-infectious causes (n = 26), and otters that died in emaciated condition with no evidence of another cause of death (n = 27). Concentrations of essential elements in sea otters varied within an order of magnitude, whereas concentrations of non-essential elements varied by two to five orders of magnitude. Hepatic concentrations of Cu and Cd were 10- to 100-fold higher in the sea otters in this study than concentrations reported for any other marine mammal species. Concentrations of Mn, Co, Zn, and Cd were elevated in the diseased and emaciated sea otters relative to the non-diseased sea otters. Elevated concentrations of essential elements such as Mn, Zn, and Co in the diseased/emaciated sea otters suggest that induction of synthesis of metallothionein and superoxide dismutase (SOD) enzyme is occurring in these animals, as a means of protecting the cells from oxidative stress-related injuries. Trace element profiles in diseased and emaciated sea otters suggest that oxidative stress mediates the perturbation of essential-element concentrations. Elevated concentrations of toxic metals such as Cd, in addition to several

Exterior view of the ISS taken during a session of EVA

NASA Image and Video Library

2011-07-12

ISS028-E-016225 (12 July 2011) --- Components of the International Space Station, though moving along at 17,500 miles per hour, appear to hover above the Pacific Ocean just off the California coast. Ten cosmonauts and astronauts were working together when this photo was taken -- four of them as STS-135 visitors from the docked space shuttle Atlantis and six as members of the Expedition 28 crew. The Cupola, near center of frame, is attached to Node 3 or Tranquility. A Russian Soyuz and a Russian Progress spacecraft are parked at the station, left side of frame. While much of the coast is obscured by clouds, just inland from left to right, one can see the agriculture of the San Joaquin Valley, the southern Sierra Nevada, the Los Angeles Basin (center), the Mojave Desert, coastal mountains of southern California, the Salton Sea, the Imperial Valley, and the mouth of the Colorado River on the extreme right edge.

Attendance patterns of California sea lion (Zalophus californianus) females and pups during the non-breeding season at San Miguel Island

USGS Publications Warehouse

Melin, S.R.; DeLong, R.L.; Thomason, J.R.; VanBlaricom, G.R.

2000-01-01

The attendance patterns of California sea lions were studied during the non-breeding seasons from 1991 to 1994. Lactating females frequented the rookery to nurse their pups until weaning; most non-lactating females left the rookery for the season. Females spent over 70% of their time at sea except in 1993 when they spent 59% of their time at sea. The mean foraging trip length in the winter and spring ranged from 3.3 to 4.6 d; the mean nursing visit ranged from 1.2 to 1.4 d. The duration of foraging trips and nursing visits was variable over the season for individuals but no pattern of change was detected. Interannual and seasonal differences were not significant for time at sea, visits ashore, or foraging-trip duration before, during, or after the 1992-1993 El Nino event. Pups spent an average of 66.6% of their time ashore and up to three days away from the rookery during their mother's absence. Most females and pups stayed associated until April or May. The results suggest that seasonal movement of prey is more important in determining attendance patterns late in the lactation period than increasing energy demands of the pup.

Loss of genetic diversity in sea otters (Enhydra lutris) associated with the fur trade of the 18th and 19th centuries

USGS Publications Warehouse

Larson, S.; Jameson, R.; Etnier, M.; Flemings, M.; Bentzen, P.

2002-01-01

During 1969 and 1970, surveys of the endangered Yuma Clapper Rail were conducted using taped calls to elicit responses from the birds. During the two summers, more than 158 Yuma clappers were located in cattailtule marshes along the Colorado River south of Needles, California, to the International Boundary, a distance of about 240 miles. Clappers (probably of the same race) were also found in estuarian marshes of the Colorado River Delta of Mexico; in the Salton Sea; in two freshwater marsh areas near Phoenix, Arizona; and in two freshwater marshes adjacent to the lower Gila River near Tacna, Arizona.....Populations of Sonora Clapper Rails were discovered as permanent residents in five separate mangrove swamps along the west coast of Mexico in the vicinity of Kino Bay, Sonora. These observations were farther north than any heretofore reported for the race R. l. rhizophorae, and the swamps also represent the extreme northward limit of mangroves in Sonora.....During the winter, Yuma clappers did not respond to taped calls north of the International Boundary, whereas clappers along the coast of Sonora readily answered the calls during the same period of time. We conclude that most Yuma Clapper Rails migrate from their summer habitat along the Colorado River in September and do not return to the breeding areas until late April.

9. Historic American Buildings Survey C.W.J. Johnson's Views of California ...

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

9. Historic American Buildings Survey C.W.J. Johnson's Views of California Scenery - Ed Grabhorn's Collection San Francisco, California About 1870 - Mission San Carlos Borromeo, Rio Road & Lausen Drive, Carmel-by-the-Sea, Monterey County, CA

The role of internal variability in prolonging the California drought

NASA Astrophysics Data System (ADS)

Buenning, N. H.; Stott, L. D.

2015-12-01

The current drought in California has been one of the driest on record. Using atmospheric general circulation models (AGCMs), recent studies have demonstrated that the low precipitation anomalies observed during the first three winters of the current drought are mostly attributable to changes in sea surface temperature (SST) and sea ice forcing. Here we show through AGCM simulations that the fourth and latest winter of the current drought is not attributable to SST and sea ice forcing, but instead a consequence of higher internal variability. Using the Global Spectral Model (GSM) we demonstrate how the surface forcing reproduces dry conditions over California for the first three winters of the current drought, similar to what other models produced. However, when forced with the SST and sea ice conditions for the winter of 2014-2015, GSM robustly simulates high precipitation conditions over California. This significantly differs with observed precipitation anomalies, which suggests a model deficiency or large influence of internal variability within the climate system during the winter of 2014-2015. Ensemble simulations with 234 realizations reveal that the surface forcing created a broader range of precipitation possibilities over California. Thus, the surface forcing caused a greater degree of internal variations, which was driven by a reduced latitudinal temperature gradient and amplified planetary waves over the Pacific. Similar amplified waves are also seen in 21st century climate projections of upper-level geopotential heights, suggesting that 21st century precipitation over California will become more variable and increasingly difficult to predict on seasonal timescales. When an El Nino pattern is applied to the surface forcing the precipitation further increases and the variance amongst model realizations is reduced, which indicates a strong likelihood of an anomalously wet 2015-2016 winter season.

Coachella Valley, CA

NASA Image and Video Library

2001-10-22

These band composites, acquired on June 4, 2000, cover a 11 by 13.5 km sub-scene in the Coachella Valley, CA. The area is shown by the yellow box on the full scene in the LOWER RIGHT corner, northwest of the Salton Sea. This is a major agricultural region of California, growing fruit and produce throughout the year. Different combinations of ASTER bands help identify the different crop types. UPPER LEFT: bands 3, 2, 1 as red, green, and blue (RGB); UPPER RIGHT: bands 4, 2, 1 as RGB; LOWER LEFT: bands 4, 3, 2 as RGB. The image is centered at 33.6 degrees north latitude, 116.1 degrees west longitude. http://photojournal.jpl.nasa.gov/catalog/PIA11161

Boron isotope evidence for the involvement of non-marine evaporites in the origin of the Broken Hill ore deposits

USGS Publications Warehouse

Slack, J.F.; Palmer, M.R.; Stevens, B.P.J.

1989-01-01

IDENTIFYING the palaeogeographic setting and mode of origin of stratabound ore deposits can be difficult in high-grade metamorphic terranes, where the effects of metamorphism may obscure the nature of the protoliths. Here we report boron isotope data for tourmalines from the early Proterozoic Broken Hill block, in Australia, which hosts giant lead-zinc-silver sulphide deposits. With one exception the 11B/10B ratios are lower than those for all other tourmalines from massive sulphide deposits and tour-malinites elsewhere in the world. We propose that these low ratios reflect leaching of boron from non-marine evaporitic borates by convecting hydrothermal fluids associated with early Proterozoic continental rifting. A possible modern analogue is the Salton Sea geothermal field in California. ?? 1989 Nature Publishing Group.

Salton Seismic Imaging Project Line 6: San Andreas Fault and Northern Coachella Valley Structure, Riverside and San Bernardino Counties, California

NASA Astrophysics Data System (ADS)

Catchings, R. D.; Fuis, G.; Rymer, M. J.; Goldman, M.; Tarnowski, J. M.; Hole, J. A.; Stock, J. M.; Matti, J. C.

2012-12-01

The Salton Seismic Imaging Project (SSIP) is a large-scale, active- and passive-source seismic project designed to image the San Andreas fault (SAF) and adjacent basins (Imperial and Coachella Valleys) in southernmost California. Data and preliminary results from many of the seismic profiles are reported elsewhere (including Fuis et al., Rymer et al., Goldman et al., Langenheim et al., this meeting). Here, we focus on SSIP Line 6, one of four 2-D seismic profiles that were acquired across the Coachella Valley. The 44-km-long, SSIP-Line-6 seismic profile extended from the east flank of Mt. San Jacinto northwest of Palm Springs to the Little San Bernardino Mountains and crossed the SAF (Mission Creek (MCF), Banning (BF), and Garnet Hill (GHF) strands) roughly normal to strike. Data were generated by 10 downhole explosive sources (most spaced about 3 to 5 km apart) and were recorded by approximately 347 Texan seismographs (average spacing 126 m). We used first-arrival refractions to develop a P-wave refraction tomography velocity image of the upper crust along the seismic profile. The seismic data were also stacked and migrated to develop low-fold reflection images of the crust. From the surface to about 7 km depth, P-wave velocities range from about 2.5 km/s to about 7.2 km/s, with the lowest velocities within an ~2-km-deep, ~20-km-wide basin, and the highest velocities below the transition zone from the Coachella Valley to Mt. San Jacinto and within the Little San Bernardino Mountains. The BF and GHF strands bound a shallow sub-basin on the southwestern side of the Coachella Valley, but the underlying shallow-depth (~4 km) basement rocks are P-wave high in velocity (~7.2 km/s). The lack of a low-velocity zone beneath BF and GHF suggests that both faults dip northeastward. In a similar manner, high-velocity basement rocks beneath the Little San Bernardino Mountains suggest that the MCF dips vertically or southwestward. However, there is a pronounced low-velocity zone

THERMAL, MIXING, AND OXYGEN REGIMES OF THE SALTON SEA, CALIFORNIA, 1997-1999. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

PLEUROCHRYSIS PSEUDOROSCOFFENSIS (PRYMNESIOPHYCEAE) BLOOMS ON THE SURFACE OF THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

CHATTONELLA MARINA (RAPHIDOPHYCEAE), A POTENTIALLY TOXIC ALGA IN THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Late Quaternary depositional history, Holocene sea-level changes, and vertical crustal movement, southern San Francisco Bay, California

USGS Publications Warehouse

Atwater, Brian F.; Hedel, Charles W.; Helley, Edward J.

1977-01-01

Sediments collected for bridge foundation studies at southern San Francisco Bay, Calif., record estuaries that formed during Sangamon (100,000 years ago) and post-Wisconsin (less than 10,000 years ago) high stands of sea level. The estuarine deposits of Sangamon and post-Wisconsin ages are separated by alluvial and eolian deposits and by erosional unconformities and surfaces of nondeposition, features that indicate lowered base levels and oceanward migrations of the shoreline accompanying low stands of the sea. Estuarine deposits of mid-Wisconsin age appear to be absent, suggesting that sea level was not near its present height 30,000–40,000 years ago in central California. Holocene sea-level changes are measured from the elevations and apparent 14C ages of plant remains from 13 core samples. Uncertainties of ±2 to ±4 m in the elevations of the dated sea levels represent the sum of errors in determination of (1) sample elevation relative to present sea level, (2) sample elevation relative to sea level at the time of accumulation of the dated material, and (3) postdepositional subsidence of the sample due to compaction of underlying sediments. Sea level in the vicinity of southern San Francisco Bay rose about 2 cm/yr from 9,500 to 8,000 years ago. The rate of relative sea-level rise then declined about tenfold from 8,000 to 6,000 years ago, and it has averaged 0.1–0.2 cm/yr from 6,000 years ago to the present. This submergence history indicates that the rising sea entered the Golden Gate 10,000–11,000 years ago and spread across land areas as rapidly as 30 m/yr until 8,000 years ago. Subsequent shoreline changes were more gradual because of the decrease in rate of sea-level rise. Some of the sediments under southern San Francisco Bay appear to be below the level at which they initially accumulated. The vertical crustal movement suggested by these sediments may be summarized as follows: (1) Some Quaternary(?) sediments have sustained at least 100 m of

DDT exposure of zebrafish embryos enhances seizure susceptibility: relationship to fetal p,p'-DDE burden and domoic acid exposure of California sea lions.

PubMed

Tiedeken, Jessica A; Ramsdell, John S

2009-01-01

California sea lions have a large body burden of organochlorine pesticides, and over the last decade they have also been subject to domoic acid poisoning. Domoic acid poisoning, previously recognized in adult animals, is now viewed as a major cause of prenatal mortality. The appearance of a chronic juvenile domoic acid disease in the sea lions, characterized by behavioral abnormalities and epilepsy, is consistent with early life poisoning and may be potentiated by organochlorine burden. We investigated the interactive effect of DDT (dichlorodiphenyltrichloroethane) on neurodevelopment using a zebrafish (Danio rerio) model for seizure behavior to examine the susceptibility to domoic acid-induced seizures after completion of neurodevelopment. Embryos were exposed (6-30 hr postfertilization) to either o,p'-DDT or p,p'-DDE (dichlorodiphenyldichloroethylene) during neurodevelopment via a 0.1% dimethyl sulfoxide solution. These larval (7 days postfertilization) fish were then exposed to either the seizure-inducing drug pentylenetetrazol (PTZ) or domoic acid; resulting seizure behavior was monitored and analyzed for changes using cameras and behavioral tracking software. Embryonic exposure to DDTs enhanced PTZ seizures and caused distinct and increased seizure behaviors to domoic acid, most notably a type of head-shaking behavior. These studies demonstrate that embryonic exposure to DDTs leads to asymptomatic animals at completion of neurodevelopment with greater sensitivity to domoic acid-induced seizures. The body burden levels of p,p'-DDE are close to the range recently found in fetal California sea lions and suggest a potential interactive effect of p,p'-DDE embryonic poisoning and domoic acid toxicity.

Spatial and temporal patterns across an ecological boundary: Allochthonous effects of a young saltwater lake on a desert ecosystem

USGS Publications Warehouse

Brehme, C.S.; Boarman, W.I.; Hathaway, S.A.; Herring, A.; Lyren, L.; Mendelsohn, M.; Pease, K.; Rahn, M.; Rochester, C.; Stokes, D.; Turschak, G.; Fisher, R.N.

2009-01-01

We documented changes in the abundance and composition of terrestrial flora and fauna with respect to distance from the sea edge and timing of large allochthonous inputs from the Salton Sea, California. We found significant effects that were most pronounced within 300 m of the shore, but extended 3 km inland via coyote scat deposition. The zone within 300 m of the sea had a higher density of vegetation with a distinctly different plant composition. The denser vegetation supported higher abundances of birds and reptiles. Coyotes exhibited spatial and temporal responses to marine subsidies of fish, while birds were likely subsidized by aquatic aerial insects. Top-down control, as well as dietary and habitat preferences, may have resulted in reduced number of ants, beetles, and small mammals near the sea. Species responses to the habitat edge appeared to be associated with life history, as the near shore habitat favored habitat generalists and shore specialists, while inland desert habitat favored many sand and open desert specialists. Ecosystem responses support current theories of allochthonous spatial subsidies and consumer-resource dynamics but were limited in scope, magnitude, and distance.

ISOLATION AND CHARACTERIZATION OF A NOVEL MARINE BRUCELLA FROM A SOUTHERN SEA OTTER (ENHYDRA LUTRIS NEREIS), CALIFORNIA, USA.

PubMed

Miller, Melissa A; Burgess, Tristan L; Dodd, Erin M; Rhyan, Jack C; Jang, Spencer S; Byrne, Barbara A; Gulland, Frances M D; Murray, Michael J; Toy-Choutka, Sharon; Conrad, Patricia A; Field, Cara L; Sidor, Inga F; Smith, Woutrina A

2017-04-01

We characterize Brucella infection in a wild southern sea otter ( Enhydra lutris nereis) with osteolytic lesions similar to those reported in other marine mammals and humans. This otter stranded twice along the central California coast, US over a 1-yr period and was handled extensively at two wildlife rehabilitation facilities, undergoing multiple surgeries and months of postsurgical care. Ultimately the otter was euthanized due to severe, progressive neurologic disease. Necropsy and postmortem radiographs revealed chronic, severe osteoarthritis spanning the proximal interphalangeal joint of the left hind fifth digit. Numerous coccobacilli within the joint were strongly positive on Brucella immunohistochemical labelling, and Brucella sp. was isolated in pure culture from this lesion. Sparse Brucella-immunopositive bacteria were also observed in the cytoplasm of a pulmonary vascular monocyte, and multifocal granulomas were observed in the spinal cord and liver on histopathology. Findings from biochemical characterization, 16S ribosomal DNA, and bp26 gene sequencing of the bacterial isolate were identical to those from marine-origin brucellae isolated from cetaceans and phocids. Although omp2a gene sequencing revealed 100% homology with marine Brucella spp. infecting pinnipeds, whales, and humans, omp2b gene sequences were identical only to pinniped-origin isolates. Multilocus sequence typing classified the sea otter isolate as ST26, a sequence type previously associated only with cetaceans. Our data suggest that the sea otter Brucella strain represents a novel marine lineage that is distinct from both Brucella pinnipedialis and Brucella ceti. Prior reports document the zoonotic potential of the marine brucellae. Isolation of Brucella sp. from a stranded sea otter highlights the importance of wearing personal protective equipment when handling sea otters and other marine mammals as part of wildlife conservation and rehabilitation efforts.

Contaminants still high in top-level carnivores in the Southern California Bight: levels of DDT and PCBs in resident and transient pinnipeds.

PubMed

Blasius, Mary Ellen; Goodmanlowe, Gwen D

2008-12-01

Highly industrialized areas, such as the Southern California Bight, often have high levels of contaminants in marine sediments, which can cause chronic exposure to organisms long after their use has ceased. tDDT and tPCB were analyzed in the blubber of 145 stranded pinnipeds that died at local marine mammal centers between 1994 and 2006. Resident species (California sea lion and Pacific harbor seal) had significantly higher concentrations of tDDT and tPCB than the transient species (northern elephant seal). Adult female California sea lions had significantly lower concentrations of tDDT and tPCB than pups, yearlings, and adult males. Concentrations of both tDDT and tPCB in California sea lions significantly declined over time, but did not change in northern elephant seals. Current concentrations of tDDT and tPCB in California sea lions and harbor seals are among the highest values reported worldwide for marine mammals and exceed those reported to cause adverse health effects.

Current prevalence of adult Uncinaria spp. in northern fur seal (Callorhinus ursinus) and California sea lion (Zalophus californianus) pups on San Miguel Island, California, with notes on the biology of these hookworms.

PubMed

Lyons, E T; Melin, S R; DeLong, R L; Orr, A J; Gulland, F M; Tolliver, S C

2001-06-28

A prevalence survey for hookworms (Uncinaria spp.) was done in northern fur seal (Callorhinus ursinus) and California sea lion (Zalophus californianus) pups on San Miguel Island, CA, in 2000. Intestines of dead pups were examined for adult hookworms in July. These parasites were found in 95% of 20 fur seal pups and 100% of 31 sea lion pups. The number of hookworms varied from 4 to 2142 (mean = 760) in fur seal pups and from 20 to 2634 (mean = 612) in sea lion pups. A direct relationship was evident between body condition and number of hookworms in the pups; that is, pups in poor condition had fewer hookworms than those in good condition. There was a decline in the number of hookworms in sea lion pups in 2000 compared to collections in 1996. Eggs of Uncinaria spp. were found in rectal feces (collected in late September and early October) of none of 35 (0%) live fur seal pups and 41 of 48 (85%) live sea lion pups. Packed cell volume values, determined for most of the same live pups, were essentially normal for C. ursinus but were much lower than normal for most Z. californianus. Hookworm larvae were not found in blubber of fur seal and sea lion pups or in rookery sand in July. Rookery sand, positive for live hookworm larvae when put in a refrigerator, was negative at removal 2.5 years later. The average number of eggs in utero of female hookworms was 285 for three specimens from a fur seal pup and 281 from three specimens from a sea lion pup. One hookworm larva was recovered from milk stripped from the teats of a stranded Z. californianus female at The Marine Mammal Center, Sausalito, CA.

The impact of disease in the American white pelican in North America

USGS Publications Warehouse

Rocke, Tonie E.; Converse, Kathryn A.; Meteyer, Carol U.; McLean, R.

2005-01-01

Records of reported die-offs of the American White Pelican (Pelicanus erythrorhynchos) held by the U.S. Geological Survey National Wildlife Health Center from 1978 through 2003 indicate that type C botulism (caused by Clostridium botulinum) was the major cause of mortality. In 1996, over 15,000 birds, including 8,500 American White Pelicans, were estimated to have died from type C botulism at the Salton Sea in California. This was the largest documented die-off of any pelican species and was estimated to represent 15-20% of the western metapopulation. This event was also notable in that it was the first time that fish, specifically Tilapia (Oreochromis mossambicus), were implicated as the source of type C botulinum toxin for birds. Type C botulism has recurred in both North American species of pelicans at the Salton Sea every year since, although the magnitude of mortality is much lower. West Nile virus caused mortality in both adult and immature American White Pelicans, but may have a more significant impact on nestlings. Emaciation and mortality is common in pelican nesting colonies. Further clarification of the cause of nestling mortality and the ability to differentiate background mortality from mortality due to infectious disease agents such as West Nile virus and Newcastle disease virus would be important in determining the impact of disease in pelicans. Although definitive conclusions cannot be drawn, the number of die-offs and the estimated losses of American White Pelicans appears to have increased along with declines in number in western U.S.

Active tectonics of the Imperial Valley, southern California: fault damage zones, complex basins and buried faults

NASA Astrophysics Data System (ADS)

Persaud, P.; Ma, Y.; Stock, J. M.; Hole, J. A.; Fuis, G. S.; Han, L.

2016-12-01

Ongoing oblique slip at the Pacific-North America plate boundary in the Salton Trough produced the Imperial Valley. Deformation in this seismically active area is distributed across a complex network of exposed and buried faults resulting in a largely unmapped seismic hazard beneath the growing population centers of El Centro, Calexico and Mexicali. To better understand the shallow crustal structure in this region and the connectivity of faults and seismicity lineaments, we used data primarily from the Salton Seismic Imaging Project (SSIP) to construct a P-wave velocity profile to 15 km depth, and a 3-D velocity model down to 8 km depth including the Brawley Geothermal area. We obtained detailed images of a complex wedge-shaped basin at the southern end of the San Andreas Fault system. Two deep subbasins (VP <5.65 km/s) are located in the western part of the larger Imperial Valley basin, where seismicity trends and active faults play a significant role in shaping the basin edge. Our 3-D VP model reveals previously unrecognized NE-striking cross faults that are interacting with the dominant NW-striking faults to control deformation. New findings in our profile include localized regions of low VP (thickening of a 5.65-5.85 km/s layer) near faults or seismicity lineaments interpreted as possibly faulting-related. Our 3-D model and basement map reveal velocity highs associated with the geothermal areas in the eastern valley. The improved seismic velocity model from this study, and the identification of important unmapped faults or buried interfaces will help refine the seismic hazard for parts of Imperial County, California.

Insights into alluvial fan dynamics: Evolution of the Miocene Elephant Trees Formation, Anza Borrego Desert, CA

NASA Astrophysics Data System (ADS)

Steel, E.; Simkins, L. M.; Reynolds, L.; Fidler, M. K.

2017-12-01

The Cenozoic Fish Creek - Vallecito Basin formed through extension and transtention associated with the localization of the Pacific-North American plate boundary in the Salton Trough region of Southern California. The exhumation of this basin along the hanging wall of the West Salton Detachment Fault since 1 Ma exposed a well-preserved sedimentary sequence that records an abrupt shift from the alluvial and fluvial deposits of the Elephant Trees Formation to the marine turbidites of the Latrania Formation. This transition marks the rapid marine incursion into the Gulf of California at 6.3 Ma (Dorsey et al., 2011). The Elephant Trees Formation is, therefore, a key transitional unit for understanding environmental change during the early stages of basin formation and the initial opening of the Gulf of California. Here, we present a detailed investigation of the characteristics of the Elephant Trees Formation, including bed thickness, clast size, paleoflow indicators, sedimentary structures, and sorting to understand the changing depositional environments associated with the onset of relative plate motion in the Gulf of California - Salton Trough corridor. This study aims to answer key questions regarding both regional tectonics and the dynamics of alluvial fan progradation, including 1) Does the Elephant Trees Formation record initiation of rapid basin subsidence and basinward progradation of alluvial fans? And 2) if so, what insights can the Elephant Trees Formation provide regarding the dynamics of debris flows and alluvial fan evolution? Our results improve understanding of proximal to distal facies variations within alluvial fan deposits and further refine the paleogeography during time of deposition of the Elephant Trees Formation ( 6.3 - 8.0 Ma) leading up to the timing of rapid marine incursion.

Temporal association between land-based runoff events and California sea otter (Enhydra lutris nereis) protozoal mortalities.

PubMed

Shapiro, Karen; Miller, Melissa; Mazet, Jonna

2012-04-01

Toxoplasma gondii and Sarcocystis neurona have caused significant morbidity and mortality in threatened Southern sea otters (Enhydra lutris nereis) along the central California coast. Because only terrestrial animals are known to serve as definitive hosts for T. gondii and S. neurona, infections in otters suggest a land to sea flow of these protozoan pathogens. To better characterize the role of overland runoff in delivery of terrestrially derived fecal pathogens to the near shore, we assessed the temporal association between indicators of runoff and the timing of sea otter deaths due to T. gondii and S. neurona. Sea otter stranding records 1998-2004, from Monterey and Estero bays were reviewed and cases identified for which T. gondii or S. neurona were determined to be a primary or contributing cause of death. Precipitation and stream flow data from both study sites were used as indicators of land-based runoff. Logistic regression was applied to determine if a temporal association could be detected between protozoal mortalities and runoff indicators that occur in the 2 mo preceding mortality events. A significant association was found between S. neurona otter deaths at Estero Bay and increased stream flow that occurred 30-60 days prior to mortality events. At this site, the cause of otter mortality following increased river flows was 12 times more likely to be S. neurona infection compared with nonprotozoal causes of death. There were no significant associations between the timing of T. gondii otter deaths and indicators of overland runoff. Our results indicate that the association between overland runoff and otter mortalities is affected by geography as well as parasite type, and highlight the complex mechanisms that influence transmission of terrestrially derived pathogens to marine wildlife. Policy and management practices that aim to mitigate discharges of contaminated overland runoff can aid conservation efforts by reducing pathogen pollution of coastal

Behavior of Rare Earth Element In Geothermal Systems; A New Exploration/Exploitation Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott A. Wood

2002-01-28

The goal of this four-year project was to provide a database by which to judge the utility of the rare earth elements (REE) in the exploration for and exploitation of geothermal fields in the United States. Geothermal fluids from hot springs and wells have been sampled from a number of locations, including: (1) the North Island of New Zealand (1 set of samples); (2) the Cascades of Oregon; (3) the Harney, Alvord Desert and Owyhee geothermal areas of Oregon; (4) the Dixie Valley and Beowawe fields in Nevada; (5) Palinpion, the Philippines: (6) the Salton Sea and Heber geothermal fieldsmore » of southern California; and (7) the Dieng field in Central Java, Indonesia. We have analyzed the samples from all fields for REE except the last two.« less

Visitor effects on a zoo population of California sea lions (Zalophus californianus) and harbor seals (Phoca vitulina).

PubMed

de Vere, Amber J

2018-05-01

The effects of visitor presence on zoo and aquarium animals have become increasingly well studied, using measures such as behavioral responses and exhibit usage. Many taxa remain underrepresented in this literature; this is the case for marine mammals, despite widespread public concern for their welfare in managed care settings. The current study therefore used behavioral activity budgets and exhibit usage to assess the responses of California sea lions (Zalophus californianus) and harbor seals (Phoca vitulina) to visitors at the Seal Cove exhibit at Six Flags Discovery Kingdom, Vallejo CA. Data was collected via focal follow video recordings over the summer season of 2016, and analyzed using MANCOVAs, discriminant analyses, and modified Spread of Participation Indices. The sea lions showed no significant changes in behavior when visitors were present, but did show greater preference for the water bordering visitor viewing areas during these times. Two sea lions gave birth during the study period, and showed greater preference for land areas both adjacent to and out of sight of visitors when nursing compared to while pregnant. In contrast, the harbor seals showed significant behavioral changes in the presence of visitors, including increased vigilance and feeding. This was associated with increased preferential use of water areas adjacent to the visitor viewing area. Visitors were able to purchase fish to throw to the animals, which likely contributed to the differences observed. Overall, this study found little evidence for negative visitor impacts on two pinniped species in a zoo setting. © 2018 Wiley Periodicals, Inc.

Sea otter health: challenging a pet hypothesis

USGS Publications Warehouse

Lafferty, Kevin D.

2015-01-01

A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission.

Severe bill deformity of an American Kestrel wintering in California

USGS Publications Warehouse

Iko, William M.; Dusek, Robert J.

2011-01-01

During a recent survey for West Nile virus in wild birds around the Sonny Bono Salton Sea National Wildlife Refuge, Imperial County, California (Dusek et al. 2010), we captured a female American Kestrel (Falco sparverius) with a severe bill deformity (Figure 1). The kestrel was captured on 9 March 2006, at 08:45, approximately 0.25 km south of the intersection of Wiest and Lindsey roads (33°  08' 42' N, 115° 26' 59' W) and 6 km east-northeast of Calipatria. It was caught on a bal-chatri trap baited with a domestic mouse (Berger and Mueller 1959), as were all the 208 kestrels captured during this study. The bird was initially perched on a high transmission line running along Wiest Road and was caught within 10 minutes of our setting the trap. In examining the bird, we observed that the maxilla beyond the cere was missing. The upper bill structure from the palatine process, which included part of the maxilla, the entire premaxilla, and the external rhamphotheca (the hardened keratin layer cover­ ing the premaxilla) was missing rostral to the bird's cere and nares (Threlfall 1968, Lucas and Stettenheim 1972, Proctor and Lynch 1993). The epidermal layer of the cere appeared to have fused over the remaining area between the nares where the upper bill normally would have been. The deformation did not appear to be recent or related to our trapping, as there were no obvious abrasions or open wounds in the region surrounding the nares and oropharynx or signs of recent trauma surrounding the oropharynx area. Both nares were clearly defined, and the tongue protruded from the open oropharynx area. After completing the physical examination, measurements, and obtaining a blood sample for testing for West Nile virus, we released the kestrel at the location of capture. After its release, we monitored the kestrel's behavior for approximately 30 minutes but did not observe any additional hunting.

The evolution of the southern California uplift, 1955 through 1976

USGS Publications Warehouse

Castle, Robert O.; Elliot, Michael R.; Church, Jack P.; Wood, Spencer H.

1984-01-01

The southern California uplift culminated in 1974 as a 150- km-wide crustal swell that extended about 600 km eastward and east-southeastward from Point Arguello to the Colorado River and Salton Sea, respectively; it was characterized by remarkably uniform height changes between 1959 and 1974 of 0.30-0.35 m over at least half of its 60,000-70,000 km2 area. At its zenith, the uplift included virtually the entire Transverse Ranges geologic province and parts of the Coast Ranges, San Joaquin Valley, Sierra Nevada, Basin and Range, Mojave Desert, Peninsular Ranges, and Salton Trough provinces. The alinement of the western part of the uplift closely paralleled the east-trending Transverse Ranges, whereas the southern flank of the eastern lobe roughly coincided with the west-northwest-trending San Andreas fault. The position and configuration of the uplift associate it with a singularly complex section of the boundary between the North American and Pacific plates that has certainly sustained major modification during the past 5 million years and probably during the past 1 million years. Surface deformation can be categorized as tectonic or nontectonic. Nontectonic vertical displacements associated with the activities of man have overwhelmed natural compaction and areally significant soil expansion in the southern California area. Because tectonic displacements are implicitly defined as those that cannot be otherwise explained, those vertical movements that can be reasonably attributed to artificial processes have been subtracted from our reconstructed configurations of the uplift. Hence this reconstruction has necessarily included the assembly and evaluation of an enormous volume of data on oil-field operations, changes in ground-water levels, and measured subsidence (or rebound) associated with changes in the underground fluid regimen. Measured changes in height at various stages in the evolution of the uplift have been based chiefly on first-order levelings carried out

Uranium-Series Ages of Marine Terrace Corals from the Pacific Coast of North America and Implications for Last-Interglacial Sea Level History

USGS Publications Warehouse

Muhs, D.R.; Kennedy, G.L.; Rockwell, T.K.

1994-01-01

Few of the marine terraces along the Pacific coast of North America have been dated using uranium-series techniques. Ten terrace sequences from southern Oregon to southern Baja California Sur have yielded fossil corals in quantities suitable for U-series dating by alpha spectrometry. U-series-dated terraces representing the ???80,000 yr sea-level high stand are identified in five areas (Bandon, Oregon; Point Arena, San Nicolas Island, and Point Loma, California; and Punta Banda, Baja California); terraces representing the ???125,000 yr sea-level high stand are identified in eight areas (Cayucos, San Luis Obispo Bay, San Nicolas Island, San Clemente Island, and Point Loma, California; Punta Bands and Isla Guadalupe, Baja California; and Cabo Pulmo, Baja California Sur). On San Nicolas Island, Point Loma, and Punta Bands, both the ???80,000 and the ???125,000 yr terraces are dated. Terraces that may represent the ???105,000 sea-level high stand are rarely preserved and none has yielded corals for U-series dating. Similarity of coral ages from midlatitude, erosional marine terraces with coral ages from emergent, constructional reefs on tropical coastlines suggests a common forcing mechanism, namely glacioeustatically controlled fluctuations in sea level superimposed on steady tectonic uplift. The low marine terrace dated at ???125,000 yr on Isla Guadalupe, Baja California, presumed to be tectonically stable, supports evidence from other localities for a +6-m sea level at that time. Data from the Pacific Coast and a compilation of data from other coasts indicate that sea levels at ???80,000 and ???105,000 yr may have been closer to present sea level (within a few meters) than previous studies have suggested.

Sea otter health: Challenging a pet hypothesis

PubMed Central

Lafferty, Kevin D.

2015-01-01

A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission. PMID:26155464

Oligocene tectonics and sedimentation, California

USGS Publications Warehouse

Nilsen, T.H.

1984-01-01

During the Oligocene epoch, California was marked by extensive nonmarine sedimentation, in contrast to its pre-Oligocene and post-Oligocene depositional history. The Oligocene continental deposits are especially widespread in southern California and fill a number of small and generally partly restricted basins. Fluvial facies in many basins prograded over previously deposited lower Tertiary turbidites. Volcanism, from widespread centers, was associated with the nonmarine sedimentation. However, some basins remained marine and a few contain Oligocene turbidites and pelagic sediments deposited at bathyal depths. The Oligocene redbeds of California do not form a post-orogenic molasse sequence comparable to the Old Red Sandstone or Alpine molasse. They are synorogenic and record local uplift of basins and surrounding source areas. Late Cretaceous to contemporary orogenesis in California has been generally characterized by the formation of small restricted basins of variable depth adjacent to small upland areas in response to strike-slip faulting. Deposition of Oligocene redbeds was associated with climatic change from warm and humid to cold and semiarid, and a global lowering of sea level. Oligocene tectonism occurred during the transition from subduction of the Farallon Plate to initiation of the modern San Andreas transform system. However, the major influence that caused uplift, formation of fault-bounded basins, and extensive redbed deposition, especially in southern California, was the approach of the Pacific-Farallon spreading ridge to the western margin of California. ?? 1984.

Uranium-series ages of marine terraces, La Paz Peninsula, Baja California Sur, Mexico

USGS Publications Warehouse

Sirkin, L.; Szabo, B. J.; Padilla, G.A.; Pedrin, S.A.; Diaz, E.R.

1990-01-01

Uranium-series dating of coral samples from raised marine terrace deposits between 1.5 and 10 m above sea level in the La Paz Peninsula area, Baja California Sur, yielded ages between 123 ka and 138 ka that are in agreement with previously reported results. The stratigraphy and ages of marine units near the El Coyote Arroyo indicate the presence of two high stands of the sea during the last interglacial or oxygen isotope substage 5e at about 140 ka and 123 ka. Accepting 5 m for the sea level during the last interglacial transgression, we calculate average uplift rates for the marine terraces of about ???70 mm/ka and 40 mm/ka. These slow rates of uplift indicate a relative stability of the La Paz peninsula area for the past 140 000 years. In contrast, areas of Baja California affected by major faultf experienced higher rates of uplift. Rockwell et al. (1987) reported vertical uplift rates of 180 to 300 mm/ka at Punta Banda within the Aqua Blanea fault zone in northern Baja California. ?? 1990 Springer-Verlag.

SKELETAL DEVELOPMENT IN HERMESINUM ADRIATICUM ZACHARIAS, A FLAGELLATE FROM THE SALTON SEA, CALIFORNIA. (R826552)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

The deep-sea as a final global sink of semivolatile persistent organic pollutants? Part I: PCBs in surface and deep-sea dwelling fish of the north and south Atlantic and the Monterey Bay Canyon (California).

PubMed

Froescheis, O; Looser, R; Cailliet, G M; Jarman, W M; Ballschmiter, K

2000-03-01

The understanding of the global environmental multiphase distribution of persistent organic pollutants (POPs) as a result of the physico-chemical properties of the respective compounds is well established. We have analysed the results of a vertical transport of POPs from upper water layers (0-200 m) to the deepwater region (> 800 m) in terms of the contamination of the biophase in both water layers. The contents of persistent organochlorine compounds like polychlorinated biphenyls (PCBs) in fish living in the upper water layers of the North Atlantic and the South Atlantic, and at the continental shelf of California (Marine Sanctuary Monterey Bay and its deep-sea Canyon) are compared to the levels in deep-sea or bottom dwelling fish within the same geographic area. The deep-sea biota show significantly higher burdens as compared to surface-living species of the same region. There are also indications for recycling processes of POPs--in this case the PCBs--in the biophase of the abyss as well. It can be concluded that the bio- and geo phase of the deep-sea may act similarly as the upper horizons of forest and grasslands on the continents as an ultimate global sink for POPs in the marine environment.

Sea otter mortality in fish and shellfish traps: Estimating potential impacts and exploring possible solutions

USGS Publications Warehouse

Hatfield, B.B.; Ames, J.A.; Estes, J.A.; Tinker, M.T.; Johnson, A.B.; Staedler, M.M.; Harris, M.D.

2011-01-01

Sea otters Enhydra lutris can be bycaught and drowned in fishing pots and traps, which may pose a threat to the welfare of otter populations. We explored this potential problem and its solutions using a wide variety of analyses. We exposed live California (USA) sea otters to finfish traps, lobster traps, and mock Dungeness crab traps in captive trials and found that the animals attempted to enter the circular and rectangular fyke openings, with some becoming entrapped. Using both live and dead sea otters, we found that a 3 ?? 9 inch (7.6 ?? 22.9 cm) fyke opening (1 inch narrower than the 4 ?? 9 inch [10.2 ?? 22.9 cm] openings currently used in California's commercial Dungeness crab fishery) would exclude most free-living (i.e. weaned from their mothers) otters while permitting the undiminished capture of crabs. Observer programs do not currently exist in California for these fisheries, so we calculated the effort required by an observer program to document sea otter bycatch over a range of hypothetical levels and evaluated the impact of those mortality rates on population growth. These analyses demonstrate that significant mortality from bycatch might easily go undetected, even with seemingly high levels of observer effort. As sea otters reoccupy portions of their former habitat in California, co-occurrence with finfish and shellfish traps with relatively large fyke openings will increase. ?? Inter-Research 2011.

California Cooperative Oceanic Fisheries Investigations Reports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olfe, J.; Lang, C.; Vernet, M.

1989-10-01

This document contains 15 papers. Topics include a review of some California fisheries, spawning biomass of the northern anchovy, marine fisheries, habitat alterations, fishery management, reproduction, population dynamics, acoustic Doppler currents and sea lion interaction and depredation. Each paper will be indexed and entered separately on the energy data base. 54 figs., 29 tabs. (KD)

Baja California, Mexico

NASA Technical Reports Server (NTRS)

1989-01-01

Sunglint on the surface of the Sea of Cortez near the island of Tiburon (28.5 N, 112.5W) reveals intricate patterns of internal waves under the placid surface. Mexico's state of Sonora and the Sonora Desert is on the mainland and the state of Baja California consists of the entire peninsula. The large bay on the Pacific side of Baja is Laguna Ojo de Libre (Bay of Whales) which is a breeding area for the Pacific Grey Whales.

Seasonal to Decadal-Scale Variability in Satellite Ocean Color and Sea Surface Temperature for the California Current System

NASA Technical Reports Server (NTRS)

Mitchell, B. Greg; Kahru, Mati; Marra, John (Technical Monitor)

2002-01-01

Support for this project was used to develop satellite ocean color and temperature indices (SOCTI) for the California Current System (CCS) using the historic record of CZCS West Coast Time Series (WCTS), OCTS, WiFS and AVHRR SST. The ocean color satellite data have been evaluated in relation to CalCOFI data sets for chlorophyll (CZCS) and ocean spectral reflectance and chlorophyll OCTS and SeaWiFS. New algorithms for the three missions have been implemented based on in-water algorithm data sets, or in the case of CZCS, by comparing retrieved pigments with ship-based observations. New algorithms for absorption coefficients, diffuse attenuation coefficients and primary production have also been evaluated. Satellite retrievals are being evaluated based on our large data set of pigments and optics from CalCOFI.

Marine Mammal Acoustic Monitoring and Habitat Investigation, Southern California Offshore Region

DTIC Science & Technology

2009-06-01

whales , baleen whales , odontocetes, SCORE Range , offshore southern California, CalCOFI, blue whale , humpback whale , fin whale , sea surface temperature...they have been visually and acoustically detected off California during those times of year (Forney and Barlow 1998 ; Norris et al. 1999; Oleson 2005...whereas blue whales were only rarely detected in early winter and late spring (Oleson et al. 2007). In summer, whale

California State Waters Map Series: offshore of San Gregorio, California

USGS Publications Warehouse

Cochrane, Guy R.; Dartnell, Peter; Greene, H. Gary; Watt, Janet T.; Golden, Nadine E.; Endris, Charles A.; Phillips, Eleyne L.; Hartwell, Stephen R.; Johnson, Samuel Y.; Kvitek, Rikk G.; Erdey, Mercedes D.; Bretz, Carrie K.; Manson, Michael W.; Sliter, Ray W.; Ross, Stephanie L.; Dieter, Bryan E.; Chin, John L.; Cochran, Susan A.; Cochrane, Guy R.; Cochran, Susan A.

2014-01-01

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California's State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Offshore of San Gregorio map area is located in northern California, on the Pacific coast of the San Francisco Peninsula about 50 kilometers south of the Golden Gate. The map area lies offshore of the Santa Cruz Mountains, part of the northwest-trending Coast Ranges that run roughly parallel to the San Andreas Fault Zone. The Santa Cruz Mountains lie between the San Andreas Fault Zone and the San Gregorio Fault system. The nearest significant onshore cultural centers in the map area are San Gregorio and Pescadero, both unincorporated communities with populations well under 1,000. Both communities are situated inland of state beaches that share their names. No harbor facilities are within the Offshore of San Gregorio map area. The hilly coastal area is virtually undeveloped grazing land for sheep and cattle. The coastal geomorphology is controlled by late Pleistocene and Holocene slip in the San Gregorio Fault system. A westward bend in the San Andreas Fault Zone, southeast of the map area, coupled with right-lateral movement along the San Gregorio Fault system have caused regional folding and uplift. The coastal area consists of high coastal bluffs and vertical sea cliffs. Coastal promontories in

Near-surface tomography of southern California from noise cross-correlation H/V measurements

NASA Astrophysics Data System (ADS)

Muir, J. B.; Tsai, V. C.

2016-12-01

The development of noise cross-correlation techniques constitutes one of the major advances in observational seismology in the past 15 years. The first data derived from noise cross correlations were surface wave phase velocities, but as the technique matures many more observables of noise cross-correlations are being used in seismic studies. One such observable is the horizontal-to-vertical amplitude ratio (H/V) of noise cross-correlations. We interpret the H/V ratio of noise cross correlations in terms of Rayleigh wave ellipticity. We have inverted the H/V of Rayleigh waves observed in noise cross-correlation signals to develop a 3D tomogram of Southern California. This technique has recently been employed (e.g. Lin et al. 2014) on a continental scale, using data from the Transportable Array in the period range of 8-24s. The finer inter-station spacing of the SCSN allows retrieval of high signal-to-noise ratio Rayleigh waves at a period of as low as 2s, significantly improving the vertical resolution of the resulting tomography. In addition, horizontal resolution is naturally improved by increased station density. This study constitutes a useful addition to traditional phase-velocity based tomographic inversions due to the localized sensitivity of H/V measurements to the near surface of the measurement station site. The continuous data of 222 permanent broadband stations of the Southern California Seismic Network (SCSN) were used in production of noise cross-correlation waveforms, resulting in a spatially dense set of measurements for the Southern California region in the 2-15s period band. Tectonic sub-regions including the LA Basin and Salton Trough are clearly visible due to their high short-period H/V ratios, whilst the Transverse and Peninsular ranges exhibit low H/V at all periods.

MHC class II DRB diversity predicts antigen recognition and is associated with disease severity in California sea lions naturally infected with Leptospira interrogans

USGS Publications Warehouse

Acevedo-Whitehouse, Karina; Gulland, Frances; Bowen, Lizabeth

2018-01-01

We examined the associations between California sea lion MHC class II DRB (Zaca-DRB) configuration and diversity, and leptospirosis. As Zaca-DRB gene sequences are involved with antigen presentation of bacteria and other extracellular pathogens, we predicted that they would play a role in determining responses to these pathogenic spirochaetes. Specifically, we investigated whether Zaca-DRB diversity (number of genes) and configuration (presence of specific genes) explained differences in disease severity, and whether higher levels of Zaca-DRB diversity predicted the number of specific Leptospira interrogans serovars that a sea lion's serum would react against. We found that serum from diseased sea lions with more Zaca-DRB loci reacted against a wider array of serovars. Specific Zaca-DRB loci were linked to reactions with particular serovars. Interestingly, sea lions with clinical manifestation of leptospirosis that had higher numbers of Zaca-DRB loci were less likely to recover from disease than those with lower diversity, and those that harboured Zaca-DRB.C or –G were 4.5 to 5.3 times more likely to die from leptospirosis, regardless of the infective serovars. We propose that for leptospirosis, a disadvantage of having a wider range of antigen presentation might be increased disease severity due to immunopathology. Ours is the first study to examine the importance of Zaca-DRB diversity for antigen detection and disease severity following natural exposure to infective leptospires.

10. Historic American Buildings Survey Society of California Pioneers From ...

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

10. Historic American Buildings Survey Society of California Pioneers From Vischer Drawing REAR VIEW OF MISSION About 1870 - Mission San Carlos Borromeo, Rio Road & Lausen Drive, Carmel-by-the-Sea, Monterey County, CA

Sea otters in the northern Pacific Ocean

USGS Publications Warehouse

Bodkin, James L.; Jameson, Ronald J.; Estes, James A.; LaRoe, Edward T.; Farris, Gaye S.; Puckett, Catherine E.; Doran, Peter D.; Mac, Michael J.

1995-01-01

About 250 years ago sea otters (Enhydra lutris) were distributed continuously from central Baja California, north and west along the Pacific Rim to Machatka Peninsula in Russia, and south along the Kuril Island to northern Japan (Kenyon 1969; Fig. 1a). Several hundred thousand sea otters may have occurred in the north Pacific region when commercial hunting began in the 18th century (Riedman and Estes 1990).At least two attributes of the sea otter have influenced humans, likely for as long as they have resided together along the coast of the north Pacific Ocean. First, sea otters rely on a dense fur, among the finest in the world, for insulation in the cold waters of the Pacific Ocean. The demand for sea otter fur led to their near extinction in the 19th century. The fur harvest, begun about 1740 and halted by international treaty in 1911, left surviving colonies, each likely numbering less than a few hundred animals, in California, south-central Alaska, and the Aleutian, Medney, and Kuril Islands (Fig. 1a). These individuals provided the nucleus for the recovery of the species. Today more than 100,000 sea otters occur throughout about 75% of their original range (fig. 1b). Immigration has resulted in near-complete occupation of the Aleutian and Kuril archipelagos and the Alaska peninsula. Successful translocations have resulted in viable populations in southeast Alaska, Washington, and British Columbia. Large amounts of unoccupied habitat remain along the coasts of Russia, Canada, the United States, and Mexico.The second potential source of conflict between sea otters and humans is that sea otters prey on and often limit some benthic invertebrate populations. Because some of these invertebrates are aso used by humans (Estes and VanBlaricom 1985), human perceptions about the effects of sea otter foraging on invertebrates sometimes differ. By limiting populations of herbivorous invertebrates (e.g., sea urchins [Echinoidea]) otters help maintain the integrity of kelp

Multibeam bathymetry and selected perspective views offshore San Diego, California

USGS Publications Warehouse

Dartnell, Peter; Normark, William R.; Driscoll, Neal W.; Babcock, Jeffrey M.; Gardner, James V.; Kvitek, Rikk G.; Iampietro, Pat J.

2007-01-01

This set of two posters consists of a map on one sheet and a set of seven perspective views on the other. The ocean floor image was generated from multibeam-bathymetry data acquired by Federal and local agencies as well as academic institutions including: - U.S. Geological Survey mapped from the La Jolla Canyon south to the US-Mexico border using a Kongsberg Simrad multibeam echosounder system (MBES) (March - April 1998). Data and metadata available at http://pubs.usgs.gov/of/2004/1221/. - Woods Hole Oceanographic Institution and SCRIPPS Institution of Oceanography mapped the majority of the La Jolla Fan Valley including the sea floor to the north and south of the valley using a Seabeam 2100 MBES. Data available at http://www.ngdc.noaa.gov/mgg/bathymetry/multibeam.html. Survey ID, AT07L09, Chief Scientists, Barrie Walden and Joseph Coburn (April 2002). - California State University, Monterey Bay, mapped Scripps Canyon and the head of La Jolla Canyon using a Reson 8101 MBES (October 2001). Data and metadata available at http://seafloor.csumb.edu/SFMLwebDATA.htm. This work was funded by the California Department of Fish and Game California Coastal Conservancy, San Diego Association of Governments (SANDAG), California Department of Fish and Game, and Fugro Pelagos mapped the nearshore region out to about 35-40 m. - The sea floor within this image that has not been mapped with MBES is filled in with interpreted bathymetry gridded from single-beam data available at http://www.ngdc.noaa.gov/mgg/bathymetry/hydro.html. Depths are in meters below sea level, which is referenced to Mean Lower Low Water.

Sea Searcher's Handbook: Activities from the Monterey Bay Aquarium.

ERIC Educational Resources Information Center

Monterey Bay Aquarium Foundation, Monterey, CA.

The activities in this book guide exploration of rocky shores, wetlands, sandy shores, kelp forests, the open sea and deep sea, and introduce students to a variety of topics and different approaches. This material is written by marine educators and was tested with over 70,000 children visiting the Monterey Bay Aquarium (California) each year. The…

Individual dietary specialization and dive behaviour in the California sea otter: Using archival time depth data to detect alternative foraging strategies

NASA Astrophysics Data System (ADS)

Tinker, M. T.; Costa, D. P.; Estes, J. A.; Wieringa, N.

2007-02-01

The existence of individual prey specializations has been reported for an ever-growing number of taxa, and has important ramifications for our understanding of predator-prey dynamics. We use the California sea otter population as a case study to validate the use of archival time-depth data to detect and measure differences in foraging behaviour and diet. We collected observational foraging data from radio-tagged sea otters that had been equipped with Mk9 time depth recorders (TDRs, Wildlife Computers, Redmond, WA). After recapturing the study animals and retrieving the TDRs it was possible to compare the two data types, by matching individual dives from the TDR record with observational data and thus examining behavioural correlates of capture success and prey species. Individuals varied with respect to prey selection, aggregating into one of three distinct dietary specializations. A number of TDR-derived parameters, particularly dive depth and post-dive surface interval, differed predictably between specialist types. A combination of six dive parameters was particularly useful for discriminating between specialist types, and when incorporated into a multivariate cluster analysis, these six parameters resulted in classification of 13 adult female sea otters into three clusters that corresponded almost perfectly to the diet-based classification (1 out of 13 animals was misclassified). Thus based solely on quantifiable traits of time-depth data that have been collected over an appropriate period (in this case 1 year per animal), it was possible to assign female sea otters to diet type with >90% accuracy. TDR data can thus be used as a tool to measure the degree of individual specialization in sea otter populations, a conclusion that will likely apply to other diving marine vertebrates as well. Our ultimate goals must be both to understand the causes of individual specialization, and to incorporate such variation into models of population- and community-level food web

Sea-level and tectonic control of middle to late Pleistocene turbidite systems in Santa Monica Basin, offshore California

USGS Publications Warehouse

Normark, W.R.; Piper, D.J.W.; Sliter, R.

2006-01-01

Small turbidite systems offshore from southern California provide an opportunity to track sediment from river source through the turbidity-current initiation process to ultimate deposition, and to evaluate the impact of changing sea level and tectonics. The Santa Monica Basin is almost a closed system for terrigenous sediment input, and is supplied principally from the Santa Clara River. The Hueneme fan is supplied directly by the river, whereas the smaller Mugu and Dume fans are nourished by southward longshore drift. This study of the Late Quaternary turbidite fill of the Santa Monica Basin uses a dense grid of high-resolution seismic-reflection profiles tied to new radiocarbon ages for Ocean Drilling Program (ODP) Site 1015 back to 32 ka. Over the last glacial cycle, sedimentation rates in the distal part of Santa Monica Basin averaged 2-3 mm yr-1, with increases at times of extreme relative sea-level lowstand. Coarser-grained mid-fan lobes prograded into the basin from the Hueneme, Mugu and Dume fans at times of rapid sea-level fall. These pulses of coarse-grained sediment resulted from river channel incision and delta cannibalization. During the extreme lowstand of the last glacial maximum, sediment delivery was concentrated on the Hueneme Fan, with mean depositional rates of up to 13 mm yr-1 on the mid- and upper fan. During the marine isotope stage (MIS) 2 transgression, enhanced rates of sedimentation of > 4 mm yr-1 occurred on the Mugu and Dume fans, as a result of distributary switching and southward littoral drift providing nourishment to these fan systems. Longer-term sediment delivery to Santa Monica Basin was controlled by tectonics. Prior to MIS 10, the Anacapa ridge blocked the southward discharge of the Santa Clara River into the Santa Monica Basin. The pattern and distribution of turbidite sedimentation was strongly controlled by sea level through the rate of supply of coarse sediment and the style of initiation of turbidity currents. These two

Modeling the Seasonal and Interannual Variability of the Northern Gulf of California Salinity

DTIC Science & Technology

2011-02-15

Schwartzlose (1979), Masas de agua del Golfo de California, Cienc . Mar., 6, 43–63. Argote, M. L., A. Amador, M. F. Lavı’n, and J. R. Hunter (1995...entrance of the Gulf of California, Mexico, Cienc . Mar., 26, 561–583. Enfield, D. B. (1987), The intraseasonal oscillation in eastern Pacific sea levels

78 FR 66269 - Safety Zone, Sea World Fireworks; Mission Bay, San Diego, CA

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-05

...-AA00 Safety Zone, Sea World Fireworks; Mission Bay, San Diego, CA AGENCY: Coast Guard, DHS. ACTION... waters of Mission Bay in San Diego, California for Sea World Fireworks on the evenings of November 15 and... firework event that is part of Sea World Christmas festivities. This safety zone is necessary to provide...

Late Quaternary sea-level history and the antiquity of mammoths (Mammuthus exilis and Mammuthus columbi), Channel Islands NationalPark, California, USA

USGS Publications Warehouse

Muhs, Daniel R.; Simmons, Kathleen R.; Groves, Lindsey T.; McGeehin, John P.; Schumann, R. Randall; Agenbroad, Larry D.

2015-01-01

Fossils of Columbian mammoths (Mammuthus columbi) and pygmy mammoths (Mammuthus exilis) have been reported from Channel Islands National Park, California. Most date to the last glacial period (Marine Isotope Stage [MIS] 2), but a tusk of M. exilis (or immature M. columbi) was found in the lowest marine terrace of Santa Rosa Island. Uranium-series dating of corals yielded ages from 83.8 ± 0.6 ka to 78.6 ± 0.5 ka, correlating the terrace with MIS 5.1, a time of relatively high sea level. Mammoths likely immigrated to the islands by swimming during the glacial periods MIS 6 (~ 150 ka) or MIS 8 (~ 250 ka), when sea level was low and the island–mainland distance was minimal, as during MIS 2. Earliest mammoth immigration to the islands likely occurred late enough in the Quaternary that uplift of the islands and the mainland decreased the swimming distance to a range that could be accomplished by mammoths. Results challenge the hypothesis that climate change, vegetation change, and decreased land area from sea-level rise were the causes of mammoth extinction at the Pleistocene/Holocene boundary on the Channel Islands. Pre-MIS 2 mammoth populations would have experienced similar or even more dramatic changes at the MIS 6/5.5 transition.

Role of ocean evaporation in California droughts and floods

NASA Astrophysics Data System (ADS)

Wei, Jiangfeng; Jin, Qinjian; Yang, Zong-Liang; Dirmeyer, Paul A.

2016-06-01

Since winter 2011, a record-breaking drought has occurred in California. Studies found that the drought is mainly caused by a persistent high-pressure system off the U.S. West Coast, which is linked to Pacific sea surface temperature anomalies. The water cycles associated with the droughts and floods are still not clearly understood. Here we show that the atmospheric circulation off the West Coast not only controls the atmospheric convergence and formation of precipitation but also largely determines surface wind speed, which further affects the evaporation over the eastern North Pacific, the major evaporative moisture source for California precipitation. Because of this mechanism, the ocean evaporation over the eastern North Pacific has been reduced during the recent drought. However, the ocean evaporation anomalies have little direct influence on California precipitation, especially during dry years, mainly because of their weak amplitudes. The California droughts cannot be readily attributed to the reduced ocean evaporation. The association between increased Pacific evaporation and floods over California is somewhat stronger.

California Ocean Research: A Sea Grant Sampler. Sea Grant Publication No. 65, Spring 1978.

ERIC Educational Resources Information Center

Brownlee, Shannon; And Others

This booklet, written, illustrated, edited, and produced by four interns from the science writing program of the University of California, Santa Cruz, explains seven ocean research projects. The projects are in the fields of: energy, marine education, fishery management, coastal zone management, marine advisory services, aquaculture, and new…

Predictability of the California Current System

NASA Technical Reports Server (NTRS)

Miller, Arthur J.; Chereskin, T.; Cornuelle, B. D.; Niiler, P. P.; Moisan, J. R.; Lindstrom, Eric (Technical Monitor)

2001-01-01

The physical and biological oceanography of the Southern California Bight (SCB), a highly productive subregion of the California Current System (CCS) that extends from Point Conception, California, south to Ensenada, Mexico, continues to be extensively studied. For example, the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program has sampled this region for over 50 years, providing an unparalleled time series of physical and biological data. However, our understanding of what physical processes control the large-scale and mesoscale variations in these properties is incomplete. In particular, the non-synoptic and relatively coarse spatial sampling (70km) of the hydrographic grid does not completely resolve the mesoscale eddy field (Figure 1a). Moreover, these unresolved physical variations exert a dominant influence on the evolution of the ecosystem. In recent years, additional datasets that partially sample the SCB have become available. Acoustic Doppler Current Profiler (ADCP) measurements, which now sample upper-ocean velocity between stations, and sea level observations along TOPEX tracks give a more complete picture of the mesoscale variability. However, both TOPEX and ADCP are well-sampled only along the cruise or orbit tracks and coarsely sampled in time and between tracks. Surface Lagrangian drifters also sample the region, although irregularly in time and space. SeaWiFS provides estimates of upper-ocean chlorophyll-a (chl-alpha), usually giving nearly complete coverage for week-long intervals, depending on cloud coverage. Historical ocean color data from the Coastal Zone Color Scanner (CZCS) has been used extensively to determine phytoplankton patterns and variability, characterize the primary production across the SCB coastal fronts, and describe the seasonal and interannual variability in pigment concentrations. As in CalCOFI, these studies described much of the observed structures and their variability over relatively large space and

PHARMACOKINETICS OF TRAMADOL HYDROCHLORIDE AND ITS METABOLITE O-DESMETHYLTRAMADOL FOLLOWING A SINGLE, ORALLY ADMINISTERED DOSE IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).

PubMed

Boonstra, Jennifer L; Barbosa, Lorraine; Van Bonn, William G; Johnson, Shawn P; Gulland, Frances M D; Cox, Sherry K; Martin-Jimenez, Tomas

2015-09-01

Tramadol is a synthetic, centrally acting, opiate-like analgesic that is structurally related to codeine and morphine. The objective of this study was to determine the pharmacokinetics of tramadol hydrochloride and its major active metabolite O-desmethyltramadol (M1) in the California sea lion (Zalophus californianus). A single dose of tramadol was administered orally in fish at 2 mg/kg to a total of 15 wild California sea lions admitted for rehabilitation. Twenty-four total blood samples were collected post drug administration at 10, 20, 30, and 45 min and at 1, 3, 5, 6, 8, 12, and 24 hr. Blood plasma was separated and stored at -80°C until analysis with high-performance liquid chromatography was performed to determine levels of tramadol and M1, the major active metabolite. The results indicate that the plasma levels of parent tramadol are low or negligible during the first 30-45 min and then reach the predicted mean maximum plasma concentration of 358 ng/ml at 1.52 hr. The M1 metabolite was not detectable in 21 of 24 plasma samples, below the level of quantification of 5 ng/ml in one sample, and detectable at 11 and 17 ng/ml in two of the samples. This study suggests that a 2 mg/kg dose would need to be administered every 6-8 hr to maintain concentrations of tramadol above the minimum human analgesic level for mild to moderate pain. Based on dosing simulations, a dose of 4 mg/kg q8 hr or q12 hr, on average, may represent an adequate compromise, but further studies are needed using a larger sample size. Pharmacodynamic studies are warranted to determine if tramadol provides analgesic effects in this species. The potential for tramadol toxicosis at any dose also has not been determined in this species.

The influence of El Niño-Southern Oscillation (ENSO) cycles on wave-driven sea-floor sediment mobility along the central California continental margin

USGS Publications Warehouse

Storlazzi, Curt D.; Reid, Jane A.

2010-01-01

Ocean surface waves are the dominant temporally and spatially variable process influencing sea floor sediment resuspension along most continental shelves. Wave-induced sediment mobility on the continental shelf and upper continental slope off central California for different phases of El Niño-Southern Oscillation (ENSO) events was modeled using monthly statistics derived from more than 14 years of concurrent hourly oceanographic and meteorologic data as boundary input for the Delft SWAN wave model, gridded sea floor grain-size data from the usSEABED database, and regional bathymetry. Differences as small as 0.5 m in wave height, 1 s in wave period, and 10° in wave direction, in conjunction with the spatially heterogeneous unconsolidated sea-floor sedimentary cover, result in significant changes in the predicted mobility of continental shelf surficial sediment in the study area. El Niño events result in more frequent mobilization on the inner shelf in the summer and winter than during La Niña events and on the outer shelf and upper slope in the winter months, while La Niña events result in more frequent mobilization on the mid-shelf during spring and summer months than during El Niño events. The timing and patterns of seabed mobility are addressed in context of geologic and biologic processes. By understanding the spatial and temporal variability in the disturbance of the sea floor, scientists can better interpret sedimentary patterns and ecosystem structure, while providing managers and planners an understanding of natural impacts when considering the permitting of offshore activities that disturb the sea floor such as trawling, dredging, and the emplacement of sea-floor engineering structures.

Polychlorinated biphenyls and biotransformation enzymes in three species of sea turtles from the Baja California peninsula of Mexico.

PubMed

Richardson, K L; Lopez Castro, M; Gardner, S C; Schlenk, D

2010-01-01

Concentrations of polychlorinated biphenyls (PCBs) as well as the expression patterns of cytochrome P450 (CYP) enzymes and glutathione-S-transferase (GST) activities were measured in livers of loggerhead (Caretta caretta), green (Chelonia mydas), and olive ridley (Lepidocheyls olivacea) sea turtles from the Baja California peninsula of Mexico. The mean concentrations of total PCBs were 18.1, 10.5, and 15.2 ng/g wet weight (ww) respectively for the three species and PCB 153 was the dominant congener in all samples. Total PCB concentrations were dominated by penta- and hexa-chlorinated biphenyls. The mean estimated TEQs were 42.8, 22.9, and 10.4 pg/g (ww) for loggerhead, green, and olive ridley, respectively, and more than 70% was accounted for by non-ortho PCBs. Western blots revealed the presence of hepatic microsomal proteins that cross-reacted with anti-CYP2K1 and anti-CYP3A27 antibodies but not with anti-CYP1A antibody. There were no significant differences in GST activities between species. Grouping congeners based on structure-activity relationships for CYP isoenzymes suggested limited activity of CYP1A contribution to PCB biotransformation in sea turtles. These results suggest potential accumulation of PCBs that are CYP1A substrates and provide evidence for biotransformation capacity, which differs from known animal models, highlighting the need for further studies in reptiles, particularly those threatened with extinction.

The risk of disease and threats to the wild population. Special Issue: Conservation and Management of the Southern Sea Otter

USGS Publications Warehouse

Thomas, Nancy J.; Cole, Rebecca A.

1996-01-01

The growth of the southern sea otter population has been steady, but slow in comparison to Alaskan subspecies, and range expansion in California has faltered. Slower growth is occurring in California despite birth rates comparable to those in Alaska, so biologists have reasoned that mortality is hindering the growth of the California population (Riedman and Estes 1990; see Estes et al., this issue). In order to investigate this issue, research efforts have been directed toward identifying the causes of death in southern sea otters.

Enhancement of Chlorophyll Concentration and Growing Harmful Algal Bloom Along the California Coast

NASA Astrophysics Data System (ADS)

Aceves, Joselyn; Singh, Ramesh

2016-07-01

We have carried out detailed analysis of satellite and ground data at different locations, Cal Poly, Goleta, Newport, Santa Monica, and Scripps piers and Monterey, Stearns and Santa Cruz wharfs along the California coast for the period 2008-2015. The sea surface temperature and chlorophyll concentrations derived from satellite data are analyzed together with ground observations of nitrogen, phosphorus, domoic acids and harmful algal blooms. The frequency of harmful algal blooms are found to increase in recent years depending upon the enhancement of chlorophyll concentrations and the discharges along the coast and dynamics of the sea surface temperature. The frequency of harmful algal blooms is higher in the northern California compared to southern California. The anthropogenic activities along the coast have increased which are associated with the forest fires and long range transport of dusts from Asia. The aerosol optical depth derived from satellite data during summer months seems to play an important role in the frequency of harmful algal blooms.

Persistent West Nile Virus Transmission and the Apparent Displacement St. Louis Encephalitis Virus in Southeastern California, 2003−2006

PubMed Central

REISEN, WILLIAM K.; LOTHROP, HUGH D.; WHEELER, SARAH S.; KENNSINGTON, MARC; GUTIERREZ, ARTURO; FANG, YING; GARCIA, SANDRA; LOTHROP, BRANKA

2008-01-01

West Nile virus (family Flaviviridae, genus Flavivirus, WNV) invaded the Colorado Desert biome of southern California during summer 2003 and seemed to displace previously endemic St. Louis encephalitis virus (family Flaviviridae, genus Flavivirus, SLEV, an antigenically similar Flavivirus in the Japanese encephalitis virus serocomplex). Western equine encephalomyelitis virus (family Togaviridae, genus Alphavirus, WEEV), an antigenically distinct Alphavirus, was detected during 2005 and 2006, indicating that conditions were suitable for encephalitis virus introduction and detection. Cross-protective “avian herd immunity” due to WNV infection possibly may have prevented SLEV reintroduction and/or amplification to detectable levels. During 2003−2006, WNV was consistently active at wetlands and agricultural habitats surrounding the Salton Sea where Culex tarsalis Coquillett served as the primary enzootic maintenance and amplification vector. Based on published laboratory infection studies and the current seroprevalence estimates, house sparrows, house finches, and several Ardeidae may have been important avian amplifying hosts in this region. Transmission efficiency may have been dampened by high infection rates in incompetent avian hosts, including Gamble's quail, mourning doves, common ground doves, and domestic pigeons. Early season WNV amplification and dispersal from North Shore in the southeastern portion of the Coachella Valley resulted in sporadic WNV incursions into the urbanized Upper Valley near Palm Springs, where Culex pipiens quinquefasciatus Say was the primary enzootic and bridge vector. Although relatively few human cases were detected during the 2003−2006 period, all were concentrated in the Upper Valley and were associated with high human population density and WNV infection in peridomestic populations of Cx. p. quinquefasciatus. Intensive early mosquito control during 2006 seemed to interrupt and delay transmission, perhaps setting the stage

Stormy Waters: Technology, Sea Control and Regional Warfare

DTIC Science & Technology

1994-06-01

AD-A283 945 NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA "DTIC TI ELECTETHESIS • S Sop()z 994 v G STOwM NATERS "T"CDOLOGY, SEA CNTROL AND REGIONAL... S . FUNDING NUMBERS Stormy Waters: Technology, Sea Control and Regional Warfare 6. AUTHOR( S ) David A. Schnell 7. PERFORMING ORGANIZATION NAME( S ) AND...ADDRESSRES) 8. PERFORMING ORGANIZATION Naval Postgraduate School REPORT NUMBER Monterey, CA 93943-5000 9. SPONSORING/MONITORING AGENCY NAME( S ) AND

Landslides: Geomorphology and Sea Cliff Hazard Potential, Santa Barbara - Isla Vista, California J.F. Klath and E.A. Keller

NASA Astrophysics Data System (ADS)

Klath, J. F.; Keller, E. A.

2015-12-01

sea level rise estimates, a map displaying likely position of the coastline by 2100 will be created. This information will be useful to the county of Santa Barbara, California when considering future development and hazard mitigation plans.

Geothermal induced seismicity: What links source mechanics and event magnitudes to faulting regime and injection rates?

NASA Astrophysics Data System (ADS)

Martinez-Garzon, Patricia; Kwiatek, Grzegorz; Bohnhoff, Marco; Dresen, Georg

2017-04-01

Improving estimates of seismic hazard associated to reservoir stimulation requires advanced understanding of the physical processes governing induced seismicity, which can be better achieved by carefully processing large datasets. To this end, we investigate source-type processes (shear/tensile/compaction) and rupture geometries with respect to the local stress field using seismicity from The Geysers (TG) and Salton Sea geothermal reservoirs, California. Analysis of 869 well-constrained full moment tensors (MW 0.8-3.5) at TG reveals significant non-double-couple (NDC) components (>25%) for 65% of the events and remarkably diversity in the faulting mechanisms. Volumetric deformation is clearly governed by injection rates with larger NDC components observed near injection wells and during high injection periods. The overall volumetric deformation from the moment tensors increases with time, possibly reflecting a reservoir pore pressure increase after several years of fluid injection with no significant production nearby. The obtained source mechanisms and fault orientations are magnitude-dependent and vary significantly between faulting regimes. Normal faulting events (MW < 2) reveal substantial NDC components indicating dilatancy, and they occur on varying fault orientations. In contrast, strike-slip events dominantly reveal a double-couple source, larger magnitudes (MW > 2) and mostly occur on optimally oriented faults with respect to the local stress field. NDC components indicating closure of cracks and pore spaces in the source region are found for reverse faulting events with MW > 2.5. Our findings from TG are generally consistent with preliminary source-type results from a reduced subset of well-recorded seismicity at the Salton Sea geothermal reservoir. Combined results imply that source processes and magnitudes of geothermal-induced seismicity are strongly affected by and systematically related to the hydraulic operations and the local stress state.

Sr isotope evidence for a lacustrine origin for the upper Miocene to Pliocene Bouse Formation, lower Colorado River trough, and implications for timing of Colorado Plateau uplift

USGS Publications Warehouse

Spencer, J.E.; Patchett, P.J.

1997-01-01

The upper Miocene to Pliocene Bouse Formation in the lower Colorado River trough, which consists largely of siltstone with basal tufa and marl, has been interpreted as estuarine on the basis of paleontology. This interpretation requires abrupt marine inundation that has been linked to early rifting in the Gulf of California and Salton trough. New strontium isotope measurements reported here from carbonates and invertebrate shells in the Bouse Formation reveal no evidence of marine water, but are consistent with deposition in a lake or chain of lakes fed by the Colorado River. Furthermore, the absence of a southward decrease in 87Sr/86Sr within the Bouse Formation does not support the estuarine model in which low 87Sr/86Sr marine Sr would have dominated the mouth of the hypothetical Bouse estuary. Elevation of originally marine 87Sr/86Sr in the Bouse Formation to its present level, due to postdepositional interaction with ground water, is unlikely because Sr from secondary calcite above, below, and within the Bouse Formation is consistently less radiogenic, not more, than Bouse marl and shells. In contrast to Bouse Sr, strontium from mollusks in tidal-flat and delta-front paleoenvironments in the contemporaneous Imperial Formation in the Salton trough and from the subsurface south of Yuma was derived from sea water and confirms the dominance of marine strontium near or at the mouth of the late Miocene to early Pliocene Colorado River. Inferred post-early Pliocene uplift of the Bouse Formation from below sea level to modern elevations of up to 550 m has been used to support a late Cenozoic uplift age for the nearby Colorado Plateau. This constraint on uplift timing is eliminated if the Bouse Formation is lacustrine.

Individual dietary specialization and dive behaviour in the California sea otter: Using archival time-depth data to detect alternative foraging strategies

USGS Publications Warehouse

Tinker, M.T.; Costa, D.P.; Estes, J.A.; Wieringa, N.

2007-01-01

The existence of individual prey specializations has been reported for an ever-growing number of taxa, and has important ramifications for our understanding of predator-prey dynamics. We use the California sea otter population as a case study to validate the use of archival time-depth data to detect and measure differences in foraging behaviour and diet. We collected observational foraging data from radio-tagged sea otters that had been equipped with Mk9 time depth recorders (TDRs, Wildlife Computers, Redmond, WA). After recapturing the study animals and retrieving the TDRs it was possible to compare the two data types, by matching individual dives from the TDR record with observational data and thus examining behavioural correlates of capture success and prey species. Individuals varied with respect to prey selection, aggregating into one of three distinct dietary specializations. A number of TDR-derived parameters, particularly dive depth and post-dive surface interval, differed predictably between specialist types. A combination of six dive parameters was particularly useful for discriminating between specialist types, and when incorporated into a multivariate cluster analysis, these six parameters resulted in classification of 13 adult female sea otters into three clusters that corresponded almost perfectly to the diet-based classification (1 out of 13 animals was misclassified). Thus based solely on quantifiable traits of time-depth data that have been collected over an appropriate period (in this case 1 year per animal), it was possible to assign female sea otters to diet type with >90% accuracy. TDR data can thus be used as a tool to measure the degree of individual specialization in sea otter populations, a conclusion that will likely apply to other diving marine vertebrates as well. Our ultimate goals must be both to understand the causes of individual specialization, and to incorporate such variation into models of population- and community-level food web

Discovery of three novel coccidian parasites infecting California sea lions (Zalophus californianus), with evidence of sexual replication and interspecies pathogenicity.

PubMed

Colegrove, Kathleen M; Grigg, Michael E; Carlson-Bremer, Daphne; Miller, Robin H; Gulland, Frances M D; Ferguson, David J P; Rejmanek, Daniel; Barr, Bradd C; Nordhausen, Robert; Melli, Ann C; Conrad, Patricia A

2011-10-01

Enteric protozoal infection was identified in 5 stranded California sea lions (Zalophus californianus). Microscopically, the apical cytoplasm of distal jejunal enterocytes contained multiple stages of coccidian parasites, including schizonts with merozoites and spherical gametocytes, which were morphologically similar to coccidians. By histopathology, organisms appeared to be confined to the intestine and accompanied by only mild enteritis. Using electron microscopy, both sexual (microgametocytes, macrogamonts) and asexual (schizonts, merozoites) coccidian stages were identified in enterocytes within parasitophorous vacuoles, consistent with apicomplexan development in a definitive host. Serology was negative for tissue cyst-forming coccidians, and immunohistochemistry for Toxoplasma gondii was inconclusive and negative for Neospora caninum and Sarcocystis neurona. Analysis of ITS-1 gene sequences amplified from frozen or formalin-fixed paraffin-embedded intestinal sections identified DNA sequences with closest homology to Neospora sp. (80%); these novel sequences were referred to as belonging to coccidian parasites "A," "B," and "C." Subsequent molecular analyses completed on a neonatal harbor seal (Phoca vitulina) with protozoal lymphadenitis, hepatitis, myocarditis, and encephalitis showed that it was infected with a coccidian parasite bearing the "C" sequence type. Our results indicate that sea lions likely serve as definitive hosts for 3 newly described coccidian parasites, at least 1 of which is pathogenic in a marine mammal intermediate host species.

Coccidioidomycosis in southern sea otters

USGS Publications Warehouse

Thomas, Nancy J.; Pappagianis, Demosthenes; Creekmore, Lynn H.; Duncan, Ruth M.