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Research about California, Oregon

Source-linked reports with geographic coverage including California, Oregon.

At least 91 records · Page 5Linked to original sources
USGS2010

Flightless and post-molt survival and movements of female mallards molting in Klamath Basin

Flightless and post-molt survival and movements were studied during August-May, 2001-2002, 2002- 2003 and 2006-2007 for 181 adult female Mallards (Anas platyrhynchos). Birds were radiotagged just before or early in their flightless period on four wetlands that differed in size on Klamath Basin (KB) National Wildlife Refuge complex. Flightless survival varied among years but was higher on two larger than two smaller wetlands; 30-day survival ranged from 11% (SE = 6.5%) on a small wetland in 2006 to 93% (SE = 6.5%) on a large wetland in 2001, and averaged 76.8% (SE = 6.1%). Most flightless mortality was from avian botulism (64%) and predation (26%). Of the 81 radiotagged Mallards that did not die in KB, 80% moved to the Central Valley of California (CVCA) before 31 January, 16% wintered in unknown areas, and 4% remained in KB through 31 January. Mallards departed KB 21 August-13 January (average: 11 Nov 2001, 25 Oct 2002, 19 Nov 2006). Post-molt survival during August-March in KB (20.7%, SE = 6.3%) was lower than in CVCA during this (62.9%, SE = 10.1%) and an earlier study. Survival in KB was consistently high only for females that molted in large permanent marshes, and although the impact of poor survival of molting females on Mallard population dynamics is unknown, KB water management plans should be developed that maintain these habitats.

California, Oregon↗
USGS2010

Using occupancy models to understand the distribution of an amphibian pathogen, Batrachochytrium dendrobatidis

Batrachochytrium dendrobatidis is a fungal pathogen that is receiving attention around the world for its role in amphibian declines. Study of its occurrence patterns is hampered by false negatives: the failure to detect the pathogen when it is present. Occupancy models are a useful but currently underutilized tool for analyzing detection data when the probability of detecting a species is <1. We use occupancy models to evaluate hypotheses concerning the occurrence and prevalence of B. dendrobatidis and discuss how this application differs from a conventional occupancy approach. We found that the probability of detecting the pathogen, conditional on presence of the pathogen in the anuran population, was related to amphibian development stage, day of the year, elevation, and human activities. Batrachochytrium dendrobatidis was found throughout our study area but was only estimated to occur in 53.4% of 78 populations of native amphibians and 66.4% of 40 populations of nonnative Rana catesbeiana tested. We found little evidence to support any spatial hypotheses concerning the probability that the pathogen occurs in a population, but did find evidence of some taxonomic variation. We discuss the interpretation of occupancy model parameters, when, unlike a conventional occupancy application, the number of potential samples or observations is finite.

California, Oregon↗
USGS2010

Application of the Systems Impact Assessment Model (SIAM) to fishery resource issues in the Klamath River, California

At the request of two offices of the U.S. Fish and Wildlife Service (FWS) located in Yreka and Arcata, Calif., we applied the Systems Impact Assessment Model (SIAM) to analyze a variety of water management concerns associated with the Federal Energy Regulatory Commission (FERC) relicensing of the Klamath hydropower projects or with ongoing management of anadromous fish stocks in the mainstem Klamath River, Oregon and California. Requested SIAM analyses include predicted effects of reservoir withdrawal elevations, use of full active storage in Copco and Iron Gate Reservoirs to augment spring flows, and predicted spawning and juvenile outmigration timing of fall Chinook salmon. In an effort to further refine the analysis of spring flow effects on predicted fall Chinook production, additional SIAM analyses were performed for predicted response to spring flow release variability from Iron Gate Dam, high and low pulse flow releases, the predicted effects of operational constraints for both Upper Klamath Lake water surface elevations, and projected flow releases specified in the Klamath Project 2006 Operations Plan (April 10, 2006). Results of SIAM simulations to determine flow and water temperature relationships indicate that up to 4 degrees C of thermal variability can be attributed to flow variations, but the effect is seasonal. Much more of thermal variability can be attributed to air temperature variations, up to 6 degrees C. Reservoirs affect the annual thermal signature by delaying spring warming by about 3 weeks and fall cooling by about 2 weeks. Multi-level release outlets on Iron Gate Dam would have limited utility; however, if releases are small (700 cfs) and a near-surface and bottom-level outlet could be blended, then water temperature may be reduced by 2-4 degrees C for a 4-week period during September. Using the full active storage in Copco and Iron Gate Reservoir, although feasible, had undesirable ramifications such as earlier spring warming, loss of hydropower production, and inability to re-fill the reservoirs without causing shortages elsewhere in the system. Altering spawning and outmigration timing may be important management objectives for the salmon fishery, but difficult to implement. SIAM predicted benefits that might occur if water temperature was cooler in fall and spring emergence was advanced; however, model simulations were based on purely arbitrary thermal reductions. Spring flow variability did indicate that juvenile fall Chinook rearing habitat was the major biological 'bottleneck' for year class success. Rearing habitat is maximal in a range between 4,500 and 5,500 cfs below Iron Gate Dam. These flow levels are not typically provided by Klamath River system operations, except in very wet years. The incremental spring flow analysis provided insight into when and how long a pulse flow should occur to provide predicted fall Chinook salmon production increases. In general, March 15th - April 30th of any year was the period for pulse flows and 4000 cfs was the target flow release that provided near-optimal juvenile rearing habitat. Again, competition for water resources in the Klamath River Basin may make implementation of pulsed flows difficult.

California, Oregon↗
USGS2009

Development and validation of a quantitative PCR to detect Parvicapsula minibicornis and comparison to histologically ranked infection of juvenile Chinook salmon, Oncorhynchus tshawytscha (Walbaum), from the Klamath River, USA

Parvicapsula minibicornis is a myxosporean parasite that is associated with disease in Pacific salmon during their freshwater life history phase. This study reports the development of a quantitative (real-time) polymerase chain reaction (QPCR) to detect P. minibicornis DNA. The QPCR assay targets the 18S ribosomal subunit gene. A plasmid DNA control was developed to calibrate cycle threshold (C T ) score to plasmid molecular equivalent (PME) units, a measure of gene copy number. Assay validation revealed that the QPCR was sensitive and able to detect 50 ag of plasmid DNA, which was equivalent to 12.5 PME. The QPCR assay could detect single P. minibicornis actinospores well above assay sensitivity, indicating a single spore contains at least 100 times the 18S DNA copies required for detection. The QPCR assay was repeatable and highly specific; no detectable amplification was observed using DNA from related myxozoan parasites. The method was validated using kidney tissues from 218 juvenile Chinook salmon sampled during the emigration period of March to July 2005 from the Klamath River. The QPCR assay was compared with histological examination. The QPCR assay detected P. minibicornis infection in 88.1% of the fish sampled, while histological examination detected infection in 71.1% of the fish sampled. Good concordance was found between the methods as 80% of the samples were in agreement. The majority of the disconcordant fish were positive by QPCR, with low levels of P. minibicornis DNA, but negative by histology. The majority of the fish rated histologically as having subclinical or clinical infections had high QPCR levels. The results of this study demonstrate that QPCR is a sensitive quantitative tool for evaluating P. minibicornis infection in fish health monitoring studies. ?? 2008 Blackwell Publishing Ltd.

California, Oregon↗
USGS2007

Development of the California Current during the past 12,000 yr based on diatoms and silicoflagellates

Detailed diatom and silicoflagellates records in three cores from the offshore region of southern Oregon to central California reveal the evolution of the northern part of the California Current during the past 12,000 yr. The early Holocene, prior to ∼ 9 ka, was characterized by relatively warm sea surface temperatures (SST), owing to enhanced northerly flow of the subtropical waters comparable to the modern Davidson Current. Progressive strengthening of the North Pacific High lead to intensification of the southward flow of the California Current at ∼ 8 ka, resulting in increased coastal upwelling and relatively cooler SST which persisted until ∼ 5 ka. Reduced southward flow of the California Current between ∼ 4.8 ka and 3.6 ka may have been responsible for a period of decreased upwelling. Modern seasonal oceanographic cycles, as evidenced by increased spring–early summer coastal upwelling and warming of early fall SST evolved between 3.5 and 3.2 ka. Widespread occurrence of paleoceanographic and paleoclimatic change between ∼ 3.5–3.0 ka along the eastern margins of the North Pacific was likely a response to increasing ENSO variability in the tropical Pacific.

California, Oregon↗
USGS2007

High-resolution climate records of the past 2,400 years from the offshore of northernmost California and central Oregon

High resolution diatom and pollen data from piston core TN062 0550 off northernmost California, and Kasten core WW7710A-26 off coastal Oregon, are compiled for the past 2,400 years. Diatom proxy data for Fall SST from both cores record warm SST's in the intervals from ca. AD 400 to 600, and from ca. AD 1050 to 1300 (later part of the Medieval Warm Period). The intervening AD 650 to 1000 interval, and the post-AD 1350 interval at both sites appear to be relatively cool. Whereas the pollen assemblage from TN062 0550 is dominated by coastal redwood, the pollen assemblage from WW7710A-26 displays alternating moist-dry cycles of alder vs. pine, as well as cycles of western hemlock (typical of the coastal forests of Oregon) vs. coastal redwood (typical of the coastal forests of northern California). Coincidence of intervals characterized by warmer diatom SST with drier pollen assemblages, and those of cooler diatom SST with moister pollen assemblages in the coastal Oregon core, recall the modern-day association of cool PDO with increased precipitation, and warm PDO with decreased precipitation, in the Pacific Northwest.

California, Oregon↗
USGS2006

Assessment of factors limiting Klamath River fall Chinook salmon production potential using historical flows and temperatures

We parameterized and applied a deterministic salmon production model to infer the degree to which river flows and temperatures may limit freshwater production potential of the Klamath River in California. Specific parameter requirements, data sources, and significant assumptions are discussed in detail. Model simulations covered a wide variety of historical hydrologic and meteorologic conditions for 40+ years of environmental data. The model was calibrated only qualitatively, appearing to perform well in predicted outmigrant timing, but overestimating growth. Egg-to-outmigrant survival was near that reported for other rivers north of the Klamath River. Predicted production potential appeared to be determined by multiple causes involving both regularly occurring habitat-related constraints and irregularly occurring exposure to high water temperatures. Simulated production was greatest in years of intermediate water availability and was constrained in both dry and wet years, but for different reasons. Reducing mortality associated with limitations to juvenile habitat, if possible, would be expected to have the highest payoff in increasing production. Water temperature was important in determining predicted production in some years but overall was not predicted to be as important as physical microhabitat. No single mortality cause acted as a true &ldquo;bottleneck&rdquo; on production. Model uncertainty is addressed through a sensitivity analysis. Predicted habitat area may be a large source of model uncertainty and sensitivity, but collectively, model parameters associated with timing of events (for example spawning, fry emergence, and emigration) or related triggers control much of the model sensitivity. Though model uncertainty remains, one can begin to explore potential alternatives to reduce production limitations. Specific recommendations are made regarding future study and reducing uncertainty.

California, Oregon↗
USGS2004

Waterfowl migration on Klamath Basin National Wildlife Refuges 1953-2001

The Klamath Basin National Wildlife Refuge (NWR) complex, located in northeastern California and southern Oregon, is situated on a major Pacific Flyway migration corridor connecting waterfowl breeding grounds in the north with major wintering grounds in California and Mexico. The complex comprises five waterfowl refuges including Lower Klamath NWR, Tule Lake NWR, Upper Klamath NWR, Klamath Marsh NWR, and Clear Lake NWR, and one bald eagle refuge, Bear Valley NWR. Lower Klamath and Tule Lake NWRs are the largest refuges in the complex; historically, they supported some of the greatest autumn and spring concentrations of migrating waterfowl in North America. Starting in 1953, standardized waterfowl surveys from small aircraft have been conducted in autumn through spring. This report summarizes waterfowl migration activity (i.e., abundance, species composition, distribution on refuges, and chronology) over four time periods—the long-term (1953-2001), early (1953-76), recent (1977-2001), and the most recent (1998-2001)—to describe changing patterns of migration on Klamath Basin refuges from autumn 1953 to spring 2001. Over the long term, waterfowl abundance (birds per day) on the refuge complex averaged about 1.0 million in autumn and about 360,000 in spring. A record peak count of 5.8 million waterfowl was recorded September 24-25, 1958. Average abundance of autumn staging waterfowl for the refuge complex, after reaching record levels in the 1950s and early 1960s, began a decline that lasted until the 1980s. A gradual recovery occurred during the 1990s, but autumn abundance has not recovered to pre-1970 levels. In contrast to autumn, average spring abundance was generally lower in the early decades but has gradually increased through the 1990s, particularly on Lower Klamath NWR. Dabbling ducks represented an average of 68% of all waterfowl in autumn and 55% in spring for the long term. Northern pintail ( Anas acuta ) was dominant, representing 62% of all dabblers in autumn and 51% in spring. A significant decline in pintail abundance starting in the late 1950s altered waterfowl composition on Klamath Basin refuges. As pintail declined, other species such as mallard ( Anas platyrhynchos ) and green-winged teal ( Anas crecca ) increased in abundance. Although Arctic nesting geese, including white-fronted ( Anser albifrons ), cackling Canada ( Branta canadensis minima ), white geese (lesser snow [ Chen caerulescens caerulescens ], and Ross’s [ Chen rossii ]) have become less prominent in recent decades, they reached an historically high abundance during autumn in the 1960s and 1970s, particularly on Tule Lake NWR. Tule Lake NWR supported the highest average autumn waterfowl populations until surpassed by Lower Klamath NWR around 1980. During the recent period (1977-2001), Lower Klamath NWR accounted for 60% of all waterfowl using the refuge complex in autumn and 61% in spring. Habitat diversity and wetland productivity contributed to its greater waterfowl abundance. Tule Lake NWR supported the most geese over the long term, 79% in autumn and 66% in spring; however, total waterfowl abundance on this refuge in autumn has been in decline, likely because of reduced diversity and productivity of sumps in the refuge. Upper Klamath, Klamath Marsh, and Clear Lake NWRs accounted for less than 8% of total waterfowl use in autumn and spring but provided diverse habitats for migrants. Waterfowl use-days on Klamath Basin refuges typically peaked in mid-autumn, decreased as migrants passed through the basin, and then reached a lesser peak during spring passage. Waterfowl abundance reached a pronounced peak in autumn during the early period (1953-76), but spring peak buildup was much less pronounced. For the recent period the autumn peak was more subdued. Waterfowl abundance, species composition, and distribution on Klamath Basin refuges have fluctuated over the decades and have been influenced by events such as productivity on breeding grounds and habitat conditions on wintering grounds that cause shifts in migration patterns. A major challenge for the future appears to be the availability of adequate water for wetland management on Klamath Basin refuges.

California, Oregon↗
USGS2002

Space use, migratory connectivity, and population segregation among Willets breeding in the western Great Basin

Western Willets ( Catoptrophorus semipalmatus inornatus ) were banded (n = 146 breeding adults and chicks) and radio-marked (n = 68 adults) at three western Great Basin wetland complexes to determine inter- and intraseasonal space use and movement patterns (primarily in 1998 and 1999). Birds were then tracked to overwintering sites where migratory connectivity and local movements were documented. Willets arrived synchronously at breeding sites during mid-April and spent less than 12 weeks in the Great Basin. There were no movements to other sites in the Great Basin during the breeding or postbreeding season. However, most breeding birds moved locally on a daily basis from upland nest sites to wetland foraging sites. The mean distance breeding birds were detected from nests did not differ between sexes or between members of a pair, although these distances were greater among postbreeding than breeding birds. Home-range estimates did not differ significantly between paired males and females during breeding or postbreeding. However, female home ranges were larger following breeding than during breeding. Shortly after chicks fledged, adult Willets left the Great Basin for locations primarily at coastal and estuarine sites in the San Francisco Bay area. Limited data revealed little among-site movements once Willets arrived at the coast, and birds appeared to be site faithful in subsequent winters. Winter sites of western Great Basin Willets differed from those used by birds from other areas in the subspecies' range, suggesting another subspecies or distinct population segment may exist. This study illustrates the importance of understanding movements and space use throughout the annual cycle in conservation planning.

California, Oregon↗
USGS2001

Modeling Klamath River system operations for quantity and quality

Alternative water management scenarios for a portion of the mainstem Klamath River from Keno, Oregon, to Seiad Valley, California, were evaluated using computer models of water quantity (MODSIM) and quality (HEC-5Q). These models were used to explore the potential for changing system operations to improve summer/fall water quality conditions to benefit declining anadromous fish populations such as steelhead, coho, and fall chinook salmon. By comparing and contrasting several model simulation results, some operational strategies that could improve water quality were determined. Most of the alternatives evaluated decreased water temperature less than 2°C. For some alternatives, dissolved oxygen could be changed as much as 5 mg/L, but was often reduced, rather than increased (or improved). Resource managers need to be made aware that implementation of any strategy to enhance water quality conditions in the Klamath River could produce desirable beneficial results that are both spatially and temporally limited. In addition, undesirable water quality conditions, i.e., higher water temperature or lower dissolved oxygen concentration at other upstream or downstream locations, may also result.

California, Oregon↗
USGS2001

Hot, shallow mantle melting under the Cascades volcanic arc

Melting occurs at progressively greater depths and higher temperatures from west to east across the Cascades volcanic arc in northern California, as demonstrated by compositional variations observed in high-alumina olivine tholeiites. The lavas studied erupted from seven vents defining a 75-km-long, east-west transect across the arc, from near Mount Shasta to east of Medicine Lake volcano. The increase in melting depth across the arc parallels modeled isotherms in the mantle wedge and does not parallel the inferred dip of the slab. The depth of mantle melting at which the high-alumina olivine tholeiites were created is ∼36 km at the western end of the transect and 66 km at the eastern end. The very high temperatures of dry melting so close to the crust indicate a transitory condition of the mantle.

California, Oregon↗
USGS2001

Water quality and nutrient loading in the Klamath River between Keno, Oregon and Seiad Valley, CA from 1996-1998

A water quality study was performed in the mainstem Klamath River from Keno, Oregon to Seiad Valley, California during 1996 through 1998. Four sites within the study area were continuously monitored using multiparameter recorders. Water quality sampling was also performed at these four locations in 1996 and 1997. Additional water quality sampling sites were added in 1998 for a total of 8 locations between Keno and Seiad. Temperature ranged from near zero &deg;C to >25 &deg;C with cooler temperatures in early spring and fall, and maximum temperatures occurring in july and August of each year. Dissolved oxygen concentration ranged from near zero mg/L to >13 mg/L with highest DO occurring in early spring and fall and lowest DO occurring in mid-summer. Air temperature was generally highly correlated with water temperature with r values ranging from 0.8 to 0.9 during the study period from 1996-1998. Water temperature in the study area exceeded chronic (>16&deg;C) and acute (>22&deg;C) criteria for salmonids during the summer months. Although chronic DO &laquo;7 mg/L) criteria were exceeded throughout most of the study area during the summer, in the free-flowing river below Iron Gate Dam the acute DO &laquo;5.5 mg/L) criteria were not exceeded. Nonpoint source pollution in the form of agricultural return flows, industrial, or sewage effluent entering the stream may have resulted in higher ammonia and total organic nitrogen concentrations at the upstream locations in the Klamath River study area (Keno and J.C. Boyle Powerplant). Nitrification of ammonia and organic nitrogen seemed to result in higher concentrations of nitrate in the downstream Klamath River (Iron Gate Dam). Total phosphorus concentration stayed relatively stable through the reservoirs in the study area, but decreased in the downstream direction between Iron Gate Dam and Seiad. Ortho-phosphorus concentrations increased longitudinally through the reservoirs, then decreased in the downstream direction between Iron Gate Dam and Seiad. An increase in ortho-phosphorus concentration can indicate internal cycling occurring in the reservoirs as well as photosynthesis. On an annual basis total phosphorus loading increased longitudinally from up- to downstream between Keno and Seiad. The increase was statistically significant (p =.03) indicating that the reservoirs in series in the Klamath River study area do not function as a nutrient sink. However, during the summer there was no statistically significant difference in total P loading when Keno, Iron Gate and Seia~ locations were compared, therefore, the reservoirs may act as a nutrient sink seasonally. The Klamath River study locations were generally nitrogen limited, although at Keno, a regUlar change from N limitation to P limitation occurred during the fall of all three years of the study. When the Klamath River annual nutrient loading values are compared to other rivers in the vicinity, the Carson, Truckee, and Long Tom Rivers also appear to be nutrient enriched. The Carson and South Yamhill Rivers seem to be N limited systems and the Wood, Long Tom, Snake and Truckee Rivers seem to be P limited systems. Implementing management strategies for reservoir operations to improve water quality and reduce nutrient concentration or loading in the Klamath River study area to benefit anadromous fisheries may be difficult and expensive. However, improving the thermal regime in spring to benefit YOY salmonids may be possible as is short-term relief in late summer for oversummering species. Decreases in nutrient concentration or loading accomplished through best management practices in the water shed may allow general protection of water resources in the Klamath Basin for future needs.

California, Oregon↗
USGS2000

Water quality modeling in the systems impact assessment model for the Klamath River basin - Keno, Oregon to Seiad Valley, California

This report describes the water quality model developed for the Klamath River System Impact Assessment Model (SIAM). The Klamath River SIAM is a decision support system developed by the authors and other US Geological Survey (USGS), Midcontinent Ecological Science Center staff to study the effects of basin-wide water management decisions on anadromous fish in the Klamath River. The Army Corps of Engineersa?? HEC5Q water quality modeling software was used to simulate water temperature, dissolved oxygen and conductivity in 100 miles of the Klamath River Basin in Oregon and California. The water quality model simulated three reservoirs and the mainstem Klamath River influenced by the Shasta and Scott River tributaries. Model development, calibration and two validation exercises are described as well as the integration of the water quality model into the SIAM decision support system software. Within SIAM, data are exchanged between the water quantity model (MODSIM), the water quality model (HEC5Q), the salmon population model (SALMOD) and methods for evaluating ecosystem health. The overall predictive ability of the water quality model is described in the context of calibration and validation error statistics. Applications of SIAM and the water quality model are described.

California, Oregon↗
USGS1999

Lethal levels of selected water quality variables to larval and juvenile Lost River and shortnose suckers

Resource managers hypothesize that occasional fish kills during summer-early fall in Upper Klamath Lake, Oregon, may be linked to unfavorable water quality conditions created by massive algal blooms. In a preliminary effort to address this concern, short-term (96-h-long) laboratory tests were conducted with larval and juvenile Lost River (Deltistes luxatus) and shortnose (Chasmistes brevirostris) suckers to determine the upper median lethal concentrations (LC50s; also referred to as median tolerance limits) for pH, un-ionized ammonia, and water temperature, and the lower LC50s for dissolved oxygen. The mean LC50s varied among species and life stages as follows: for pH, 10.30-10.39; for un-ionized ammonia, 0.48-1.06 mg litre-1; for temperature, 30.35-31.82??C; and for dissolved oxygen, 1.34-2.10 mg litre-1. Comparisons of 95% confidence limits indicated that, on average, the 96-h LC50s were not significantly different from those computed for shorter exposure times (i.e., 24 h, 48 h, and 72 h). According to two-way analysis of variance, LC50s for the four water quality variables did not vary significantly (p > 0.05) between fish species. However, LC50s for pH (exposure times of 24 h and 48 h) and dissolved oxygen (exposure times of 48 h, 72 h, and 96 h) differed significantly (p ??? 0.05) between life stages, whereas LC50s for un-ionized ammonia and water temperature did not exhibit significant differences. In general, larvae were more sensitive than juveniles to high pH and low dissolved oxygen concentrations. When compared to ambient water quality conditions in Upper Klamath Lake, our results strongly suggest that near-anoxic conditions associated with the senescence phase of algal blooms are most likely to cause high mortalities of larval and juvenile suckers.

California, Oregon↗