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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 1,261 records · Page 70Linked to original sources
USGS2017

The transtensional offshore portion of the northern San Andreas fault: Fault zone geometry, late Pleistocene to Holocene sediment deposition, shallow deformation patterns, and asymmetric basin growth

We mapped an ~120 km offshore portion of the northern San Andreas fault (SAF) between Point Arena and Point Delgada using closely spaced seismic reflection profiles (1605 km), high-resolution multibeam bathymetry (~1600 km 2 ), and marine magnetic data. This new data set documents SAF location and continuity, associated tectonic geomorphology, shallow stratigraphy, and deformation. Variable deformation patterns in the generally narrow (∼1 km wide) fault zone are largely associated with fault trend and with transtensional and transpressional fault bends. We divide this unique transtensional portion of the offshore SAF into six sections along and adjacent to the SAF based on fault trend, deformation styles, seismic stratigraphy, and seafloor bathymetry. In the southern region of the study area, the SAF includes a 10-km-long zone characterized by two active parallel fault strands. Slip transfer and long-term straightening of the fault trace in this zone are likely leading to transfer of a slice of the Pacific plate to the North American plate. The SAF in the northern region of the survey area passes through two sharp fault bends (∼9°, right stepping, and ∼8°, left stepping), resulting in both an asymmetric lazy Z–shape sedimentary basin (Noyo basin) and an uplifted rocky shoal (Tolo Bank). Seismic stratigraphic sequences and unconformities within the Noyo basin correlate with the previous 4 major Quaternary sea-level lowstands and record basin tilting of ∼0.6°/100 k.y. Migration of the basin depocenter indicates a lateral slip rate on the SAF of 10–19 mm/yr for the past 350 k.y. Data collected west of the SAF on the south flank of Cape Mendocino are inconsistent with the presence of an offshore fault strand that connects the SAF with the Mendocino Triple Junction. Instead, we suggest that the SAF previously mapped onshore at Point Delgada continues onshore northward and transitions to the King Range thrust.

Geosphere↗
USGS2011

Rapid growth in the early marine period improves the marine survival of Chinook salmon (Oncorhynchus tshawytscha) in Puget Sound, Washington

We examined the effect of early marine entry timing and body size on the marine (smolt-to-adult) survival of Puget Sound Chinook salmon ( Oncorhynchus tshawytscha ). We used data from coded wire tag release groups of hatchery Chinook salmon to test whether hatchery release date, release size, and size in offshore waters in July and September influenced marine survival. Marine survival was most strongly related to the average body size in July, with larger sizes associated with higher survivals. This relationship was consistent over multiple years (1997–2002), suggesting that mortality after July is strongly size-dependent. Release size and date only slightly improved this relationship, whereas size in September showed little relationship to marine survival. Specifically, fish that experienced the highest marine survivals were released before 25 May and were larger than 17 g (or 120 mm fork length) by July. Our findings highlight the importance of local conditions in Puget Sound (Washington, USA) during the spring and summer, and suggest that declines in marine survival since the 1980s may have been caused by reductions in the quality of feeding and growing conditions during early marine life.

Washington↗
USGS2003

Seismic evidence for a mantle source for mid-Proterozoic anorthosites and implications for models of crustal growth

Voluminous anorthosite intrusions are common in mid-Proterozoic crust. Historically, two end-member models have been proposed for the origin of these anorthosites. In the first model anorthosites derive from fractionation of a mantle source leaving a residue of metagabbro in the lower crust; in the second model anorthosites are the product of partial melting of the lower crust with residual pyroxene and high-grade minerals (i.e. a pyroxenitic and/or metapelitic lower crust). Although a general consensus has developed that the first model provides the best fit to petrological and geochemical constraints, the sparse evidence for mafic and ultramafic counterparts to the anorthosites leaves the issue still unresolved. We use the absolute P-wave velocity and the ratio between P- and S-wave velocities ( V P / V S ) to infer the composition of the lower crust beneath the Marcy Anorthosite (New York State, USA). Seismic refraction data reveal a lower crust 20 km thick, where V P and V P /V S range from top to bottom between 7.0 km s −1 and 7.2 ± 0.1 and 1.84 km s −1 and 1.81 ± 0.02, respectively. Laboratory measurements on rock samples indicate that these seismic properties are typical of plagioclase-rich rocks. Magmatic underplating of basaltic melts is a mechanism to form plagioclase-rich bulk composition for the Grenville crust. At the bottom of the lower crust, increase of P-wave velocity, slight decrease of V P / V S ratios and the presence of a low-reflective seismic Moho are additional observations supporting crustmantle interactions related to magmatic underplating. High P-wave velocity (8.6 km s −1 ) in the upper mantle may indicate that the ultramafic portion (e.g. pyroxenites) of the underplated magma has become eclogite. High average P-wave velocity (6.7 km s −1 ) and V P / V S (1.81), and the exceptional abundance of anorthosites-norites-troctolites among the rocks exposed at the surface, indicate that the Grenville Proterozoic crust may have a unique plagioclase-rich bulk composition. We suggest magmatic underplating, occurring either over a wide time span or with separate syn- and post-collisional magmatic pulses, as being a major crust-forming mechanism operating in mid-Proterozoic time.

Geological Society Special Publication↗
USGS2024

Morphometry, growth, and condition of hatchery-reared Cisco (Coregonus artedi) and Bloater (Coregonus hoyi)

The re-introduction of native species that have been extirpated or in low abundance in the Great Lakes has been a binational initiative between the United States and Canadian governments. Recently, new management programs have been underway that use current hatchery facilities for the restoration of native forage fishes in Lake Ontario. These species include Bloater ( Coregonus hoyi ), which has been extirpated from Lake Ontario for approximately four decades, and Cisco ( C. artedi ), which exists at a fraction of its former abundance. We assessed morphometrics, length-weight relationships, and condition factors during early life development for eight cohorts of Cisco and Bloater reared from 2012-2019. Weekly samples for Cisco and Bloater were measured from hatch until release (29-45 weeks, 133-1,002 samples annually). Head width, gape, mandible length, and mouth height metrics were all larger for Cisco than Bloater at any given size but increased at similar rates for both species. Average condition factors for Cisco and Bloater were 0.54317 and 0.55892, respectively. This information may also improve field identification of these species, helping managers evaluate the relative success of different release strategies for rehabilitation of populations of these native species.

Ecology and Evolutionary Biology↗
USGS2014

Structural equation models of VMT growth in US urbanised areas.

Vehicle miles travelled (VMT) is a primary performance indicator for land use and transportation, bringing with it both positive and negative externalities. This study updates and refines previous work on VMT in urbanised areas, using recent data, additional metrics and structural equation modelling (SEM). In a cross-sectional model for 2010, population, income and freeway capacity are positively related to VMT, while gasoline prices, development density and transit service levels are negatively related. Findings of the cross-sectional model are generally confirmed in a more tightly controlled longitudinal study of changes in VMT between 2000 and 2010, the first model of its kind. The cross-sectional and longitudinal models together, plus the transportation literature generally, give us a basis for generalising across studies to arrive at elasticity values of VMT with respect to different urban variables.

Urban Studies↗
USGS2021

Large-scale wildfire reduces population growth in a peripheral population of sage-grouse

Drastic increases in wildfire size and frequency threaten western North American sagebrush ( Artemisia L. spp.) ecosystems. At relatively large spatial scales, wildfire facilitates type conversion of sagebrush-dominated plant communities to monocultures of invasive annual grasses ( e.g., Bromus tectorum L.). Annual grasses provide fine fuels that promote fire spread, contributing to a positive grass–fire feedback cycle that affects most sagebrush ecosystems, with expected habitat loss for resident wildlife populations. Greater sage-grouse ( Centrocercus urophasianus Bonaparte, 1827) are sagebrush obligate species that are indicators of sagebrush ecosystem function because they rely on different components of sagebrush ecosystems to meet seasonal life history needs. Because wildfire cannot be predicted, chronic impacts of wildfire on sage-grouse populations have been largely limited to correlative studies. Thus, evidence from well-designed experiments is needed to understand the specific mechanisms by which wildfire is detrimental to sage-grouse population dynamics.

California, Nevada↗
USGS2012

Evidence for occurrence, persistence, and growth potential of Escherichia coli and enterococci in Hawaii’s soil environments

High densities of Escherichia coli and enterococci are common in freshwaters on Oahu and other Hawaiian Islands. Soil along stream banks has long been suspected as the likely source of these bacteria; however, the extent of their occurrence and distribution in a wide range of soils remained unknown until the current investigation. Soil samples representing the seven major soil associations were collected on the island of Oahu and analyzed for fecal coliforms, E. coli , and enterococci by the most probable number method. Fecal coliforms, E. coli , and enterococci were found in most of the samples analyzed; log mean densities (MPN ± SE g soil −1 ) were 1.96±0.18, n =61; 1.21±0.17, n =57; and 2.99±0.12, n =62, respectively. Representative, presumptive cultures of E. coli and enterococci collected from the various soils were identified and further speciated using the API scheme; at least six species of Enterococcus , including Enterococcus faecalis and Enterococcus faecium , were identified. In mesocosm studies, E. coli and enterococci increased by 100-fold in 4 days, after mixing sewage-spiked soil (one part) with autoclaved soil (nine parts). E. coli remained metabolically active in the soil and readily responded to nutrients, as evidenced by increased dehydrogenase activity. Collectively, these findings indicate that populations of E. coli and enterococci are part of the natural soil microflora, potentially influencing the quality of nearby water bodies.

Hawai'i↗
USGS2019

Projected urban growth in the Southeastern USA puts small streams at risk

Future land-use development has the potential to profoundly affect the health of aquatic ecosystems in the coming decades. We developed regression models predicting the loss of sensitive fish (R2=0.39) and macroinvertebrate (R2=0.64) taxa as a function of urban and agricultural land uses and applied them to projected urbanization of the rapidly urbanizing Piedmont ecoregion of the southeastern USA for 2030 and 2060. The regression models are based on a 2014 investigation of water quality and ecology of 75 wadeable streams across the region. Based on these projections, stream kilometers experiencing >50% loss of sensitive fish and invertebrate taxa will nearly quadruple to 19,500 and 38,950 km by 2060 (16 and 32% of small stream kilometers in the region), respectively. Uncertainty was assessed using the 20 and 80% probability of urbanization for the land-use projection model and using the 95% confidence intervals for the regression models. Adverse effects on stream health were linked to elevated concentrations of contaminants and nutrients, low dissolved oxygen, and streamflow alteration, all associated with urbanization. The results of this analysis provide a warning of potential risks from future urbanization and perhaps some guidance on how those risks might be mitigated.

PLoS ONE↗
USGS1986

Effects of supplemental feeding on growth, production, and feeding habits of striped bass in ponds

Production of fingerling striped bass (Morone saxatilis) was increased by feeding fish every hour. In a 42‐d study, survival and production averaged 52.8% and 167.9 kg/hectare (150 lb/acre) in ponds to which feed was delivered hourly and 34.9% and 110.6 kg/hectare (99 lb/acre) in ponds to which feed was delivered only twice a day. Types of food items selected by larvae and fingerlings in treatment and control groups were similar. Cladocerans, adult copepods, and chironomid larvae were the predominant food organisms eaten. Particles of supplemental prepared feed were found in 92% of the fish sampled from treatment ponds and in 89% of those from control ponds. The addition of supplemental feed appeared to enhance rather than to replace the natural diet.

Progressive Fish-Culturist↗
USGS1987

Growth and survival of fingerling lake trout reared at four densities

Fingerling lake trout (Salvelinus namaycush) were reared at density indexes (fish density, in pounds per cubic foot, divided by fish length in inches) of 0.25, 0.50, 1.0, and 2.0. Final lengths, weights, condition factors, and mortality rates did not differ among the treatments. We conclude that fingerling lake trout may be successfully reared at a density index of at least 2.0 if water requirements for respiration and waste dilution are met. Our results indicate that fish length may be less important in determining allowable fish densities than was previously suspected.

Progressive Fish-Culturist↗
USGS1988

Effect of dietary propylene glycol on growth, survival, histology, and carcass composition of Atlantic salmon

Atlantic salmon ( Salmo salar ) were fed diets containing 0, 5, 10, 15, or 25% propylene glycol (a compound used to maintain high dietary moisture levels) to determine beneficial or detrimental effects. Weight gain and feed conversion efficiency were better for fish fed the diets containing 5–15% propylene glycol than in those fed diets containing either 0 (control) or 25% propylene glycol. No histological aberrations were noted in fish from any treatment. These results indicate that propylene glycol can effectively be used to elevate moisture level in diets for Atlantic salmon and may enhance diet palatability by improving texture, flavor, or moisture content.

Progressive Fish-Culturist↗
USGS1994

Evaluation of the effects of an oxygen injection system on the growth, hematology, and immunity of lake trout

Fingerling lake trout ( Salvelinus namaycush ) were reared for 64 d at three pressures of dissolved gases, expressed in relation to saturation values (▵P)–untreated (control) water, ▵P = 10 mm Hg; water treated by column degassing with air, ▵P = 9 mm Hg; and water treated with an oxygen injection system, ▵P = −20 mm Hg. Dissolved oxygen concentration for experimental groups was increased with column degassing by 7.8% and with oxygen injection by 8.7%. Nitrogen level was reduced 2.2% with columns receiving air and 7.4% with the oxygen injection system. There were no differences in production, mean lengths, or mean weights among fish reared in the three treatments. Hematocrit, plasma protein levels, and mean antibody microtiters to injected Salmonella H antigen were not different among fish from the three water treatments.

Progressive Fish-Culturist↗
USGS1961

Records, ages, and growth of the mooneye, Hiodon tergisus, of the Great Lakes

Mooneyes (Hiodon tergisus) are very scarce in the upper three Great Lakes since only four specimens have been received from Lake Michigan, one from Lake Huron, and none from Lake Superior. The published statistics of the mooneyes are erroneous. Those of 1931 of Lake Michigan were perhaps chubs (Coregonus spp.) and those of Lake Huron of 1929 were also chubs and of 1934, 1949, and 1951 were gizzard shad (Dorosoma cepedianum) but since 1956 were alewives (Alosa pseudoharengus). Mooneyes are common in Lakes Erie and Ontario and perhaps in Lake St. Clair but are commercialized only in the States of Ohio and Michigan. Virtually all Lake Erie mooneyes were caught in trap nets, pound nets, and seines in less than 35 feet of water. Their life-history data collected in 1927-31 included lengths and weights of age-groups I-VII, calculated increments and lengths based on both anterior radii and lateral diameters of scales, length-weight relationships, and sexual maturity. Apparently mature specimens exceeded 8.8 inches, 3.25 ounces, and age-group I.

Transactions of the American Fisheries Society↗