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Historical hydrographic data from the Washington / Oregon shelf are compared for the first time to identify bathymetric change on a regional scale. Offshore data sets exist for four time periods: 1800s, pre-1950s, post-1950s, and 1990s. Data from only two time periods, 1868-87 and 1926-27, cover the entire offshore region between Tillamook Head, Oregon and Grays Harbor, Washington . A confidence interval of + or -1.7 m is established for the bathymetric comparison between these two data sets. Wide trackline spacings within the 1868/87 surveys, sounding errors due to horizontal positioning inaccuracies and heavy seas and currents encountered during the surveys, questionable tidal correction methods, and vertical datum inconsistencies, compose most of the uncertainties in this data set. Surveys collected closer to shore, in water depths less than -30 m, contain smaller errors and define the sea-floor morphology well. Errors and uncertainties increase with depth and distance offshore. Comparison between these two surveys shows large areas of both accretion and erosion on the shelf between the shoreline and -70 m of water, with the greatest change occurring off the mouth of the Columbia River. Quantitative analysis and interpretation of the regional bathymetric changes within the Columbia River Littoral Cell should be approached with caution and with a thorough knowledge of the error distribution and uncertainties associated with the data set.
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North American-Farallon-Kula plate motion data, combined with estimated strikeslip displacements obtained from the obliquity of convergence along active circumPacific subduction zones, can be used to estimate the amount of strike-slip displacement along the forearc region of western North America. This evidence suggests a minumum of 500 km and maximum of 1600 km displacement with respect to the Farallon plate, and a minumum of 1600 km and a maximum of 4900 km with respect to the Kula plate (or some equivalent) from Late Jurassic to middle Eocene (145 Ma to 43 Ma). These displacements are consistent with pre-middle Eocene displacements of paleoforearc strata (Franciscan Complex, Great Valley sequence and related units), inferred from pa 1eomagnetic, petrologic, stratigraphic, and conglomerate pebble data. Tentative restorations suggest that the Elk outlier and Snow Camp terrane of southwest Oregon have affinities with the southern Klamath Mountains of northern California; that the Gold Beach terrane of southwest Oregon has affinities with central or southern California; that the Healdsburg terrane of the San Francisco area has affinities with southern California; that other Franciscan rocks of the San Francisco area have affinities with central or southern California; and that the Nacimiento block has affinities with the Peninsular Ranges or Vizcaino area of Baja California. These tentative correlations suggest about 600-1000 km of right-lateral displacement between Early Cretaceous and middle Eocene time which can be entirely accommodated by Farallon plate motions and (or) represent minimal displacement with respect to Kula plate motions (or some equivalent).
The globally widespread amphibian fungal pathogen Batrachochytrium dendrobatidis (Bd) has been linked to amphibian declines worldwide (Lips et al. 2006; Skerratt et al. 2007). In Louisiana, USA, Bd has been found in several amphibian species (Chatfield et al. 2012; Rothermel et al. 2008), but to our knowledge no population-level die-offs have been observed. Published literature on Bd prevalence in Louisiana is scant for some amphibian species and completely absent for many others. This trend is likely driven by the perception that Bd is not a major problem in this area due to a lack of observed dieoffs attributable to chytridiomycosis.
No abstract available.
We present observations of overwintering behavior in Taricha torosa torosa larvae at two independent sites. We define overwintering larvae as newts that spend the entire winter season in the larval form. The winter season (December, January, and February) represents the average three coldest months for the southern California coastal region (Felton 1965. California’s Many Climates. Pacific Books. 169 pp.).
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Body condition, or an individual's ability to address metabolic needs, is an important measure of organism health. For waterfowl, body condition, usually some measure of fat, provides a useful proxy for assessing energy budgets during different life history periods and potentially is a measure of response to ecosystem changes. The mottled duck (Anas fulvigula) is relatively poorly studied in respect to these dynamics and presents a unique case because its non-migratory life-history strategy releases it from metabolic costs experienced by many related migratory waterfowl species. Additionally, as a species in decline and of conservation concern in many parts of its range, traditional methods of fat content estimation that involve destructive sampling are less viable. The goal of this study was to produce an equation for estimating fat content in mottled ducks using birds (n = 24) donated at hunter-check stations or collected by law enforcement efforts on the Texas Chenier Plain National Wildlife Refuge Complex from 2005 - 2007. Morphometric measurements were taken, and ether extraction and fat removal was used to estimate percent body fat content and abdominal fat mass, respectively. A hierarchical simple linear regression modeling approach was used to determine external morphometrics that best predicted abdominal fat content. A ratio model based on body mass and a length metric (keel and wing chord length possessed equal model support) provided the best relationship with abdominal fat in sampled individuals. We then applied the regression equation to historical check station data to examine fluctuations in fat content over time; fat content or condition varied relatively little with the exception of years characterized by major disturbances. The mottled duck condition model created here can be used to better monitor population status and health without destructively sampling individuals.
Coal beds are one of the most promising reservoirs for geologic carbon dioxide (CO₂) sequestration, as CO₂ can strongly adsorb onto organic matter and displace methane; however, little is known about the long-term fate of CO₂ sequestered in coal beds. The "2800' sand" of the Olla oil field is a coal-bearing, oil and gas-producing reservoir of the Paleocene–Eocene Wilcox Group in north-central Louisiana. In the 1980s, this field, specifically the 2800' sand, was flooded with CO₂ in an enhanced oil recovery (EOR) project, with 9.0×10⁷m³ of CO₂ remaining in the 2800' sand after injection ceased. This study utilized isotopic and geochemical tracers from co-produced natural gas, oil and brine from reservoirs located stratigraphically above, below and within the 2800' sand to determine the fate of the remaining EOR-CO₂, examining the possibilities of CO₂ migration, dissolution, mineral trapping, gas-phase trapping, and sorption to coal beds, while also testing a previous hypothesis that EOR-CO₂ may have been converted by microbes (CO₂-reducing methanogens) into methane, creating a microbial "hotspot". Reservoirs stratigraphically-comparable to the 2800' sand, but located in adjacent oil fields across a 90-km transect were sampled to investigate regional trends in gas composition, brine chemistry and microbial activity. The source field for the EOR-CO₂, the Black Lake Field, was also sampled to establish the δ¹³C-CO₂ value of the injected gas (0.9‰ +/- 0.9‰). Four samples collected from the Olla 2800' sand produced CO₂-rich gas with δ¹³C-CO₂ values (average 9.9‰) much lower than average (pre-injection) conditions (+15.9‰, average of sands located stratigraphically below the 2800' sand in the Olla Field) and at much higher CO₂ concentrations (24.9 mole %) than average (7.6 mole %, average of sands located stratigraphically below the 2800' sand in the Olla Field), suggesting the presence of EOR-CO₂ and gas-phase trapping as a major storage mechanism. Using δ¹³C values of CO₂ and dissolved organic carbon (DIC), CO₂ dissolution was also shown to be a major storage mechanism for 3 of the 4 samples from the Olla 2800' sand. Minor storage mechanisms were shown to be migration, which only affected 2 samples (from 1 well), and some EOR-CO₂ conversion to microbial methane for 3 of the 4 Olla 2800' sand samples. Since methanogenesis was not shown to be a major storage mechanism for the EOR-CO₂ in the Olla Field (CO₂ injection did not stimulate methanogenesis), samples were examined from adjacent oil fields to determine the cause of the Olla microbial "hot-spot". Microbial methane was found in all oil fields sampled, but indicators of methanogenesis (e.g. alkalinity, high δ¹³C-DIC values) were the greatest in the Olla Field, and the environmental conditions (salinity, pH, temperature) were most ideal for microbial CO₂ reduction in the Olla field, compared to adjacent fields.
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