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At least 1,189 records · Page 66Linked to original sources
USGS2012

Using rocks to reveal the inner workings of magma chambers below volcanoes in Alaska’s National Parks

Alaska is one of the most vigorously volcanic regions on the planet, and Alaska’s national parks are home to many of the state’s most active volcanoes. These pose both local and more distant hazards in the form of lava and pyroclastic flows, lahars (mudflows), ash clouds, and ash fall. Alaska’s volcanoes lie along the arc of the Aleutian-Alaskan subduction zone, caused as the oceanic Pacific plate moves northward and dips below the North American plate. These volcanoes form as water-rich fluid from the down-going Pacific plate is released, lowering the melting temperature of rock in the overlying mantle and enabling it to partially melt. The melted rock (magma) migrates upward, collecting at the base of the approximately 25 mile (40 km) thick crust, occasionally ascending into the shallow crust, and sometimes erupting at the earth’s surface. During volcanic unrest, scientists use geophysical signals to remotely visualize volcanic processes, such as movement of magma in the upper crust. In addition, erupted volcanic rocks, which are quenched samples of magmas, can tell us about subsurface magma characteris-tics, history, and the processes that drive eruptions. The chemical compositions of and the minerals present in the erupted magmas can reveal conditions under which these magmas were stored in crustal “chambers”. Studies of the products of recent eruptions of Novarupta (1912), Aniakchak (1931), Trident (1953-74), and Redoubt (2009) volcanoes reveal the depths and temperatures of magma storage, and tell of complex interactions between magmas of different compositions. One goal of volcanology is to determine the processes that drive or trigger eruptions. Information recorded in the rocks tells us about these processes. Here, we demonstrate how geologists gain these insights through case studies from four recent eruptions of volcanoes in Alaska national parks.

Alaska↗
USGS2022

Landscape characteristics influence projected growth rates of stream-resident juvenile salmon in the face of climate change in the Kenai River watershed, south-central Alaska

Objective Climate change is affecting the distribution and productivity of Pacific salmon throughout their range. At high latitudes, warmer temperatures have been associated with increased freshwater growth of juvenile salmon, but it is not clear how long this trend will continue before further warming leads to reduced growth. To explore the potential influence of climate warming on juvenile Chinook and Coho Salmon summer growth rates in southcentral Alaska, we coupled bioenergetics models with temperature sensitivity models for streams across the Kenai River watershed. Methods We measured diet ( n = 772 stomachs) and growth ( n = 3,791 weight/length values) under current conditions and used published air temperature projections to model growth for the 2030–2039 and 2060–2069 decades. Result We estimated direct effects of climate warming on juvenile growth (body mass at the end of May–September study period) will be primarily negative, ranging from +5.1% to −22.8% relative to a 2010–2019 baseline. Estimated effects depended on age cohort, feeding rate, and climate scenario. However, an extended growing season from warming could mitigate or offset predicted reductions in growth during midsummer. Conclusion Our results illustrate how diverse habitats are expected to produce variation in the magnitude of climate effects throughout juvenile salmon rearing environments.

Alaska↗
USGS2011

Evidence for competition at sea between Norton Sound chum salmon and Asian hatchery chum salmon

Increasing production of hatchery salmon over the past four decades has led to concerns about possible density-dependent effects on wild Pacific salmon populations in the North Pacific Ocean. The concern arises because salmon from distant regions overlap in the ocean, and wild salmon populations having low productivity may compete for food with abundant hatchery populations. We tested the hypothesis that adult length-at-age, age-at-maturation, productivity, and abundance of a Norton Sound, Alaska, chum salmon population were influenced by Asian hatchery chum salmon, which have become exceptionally abundant and surpassed the abundance of wild chum salmon in the North Pacific beginning in the early 1980s. We found that smaller adult length-at-age, delayed age-at-maturation, and reduced productivity and abundance of the Norton Sound salmon population were associated with greater production of Asian hatchery chum salmon since 1965. Modeling of the density-dependent relationship, while controlling for other influential variables, indicated that an increase in adult hatchery chum salmon abundance from 10 million to 80 million adult fish led to a 72% reduction in the abundance of the wild chum salmon population. These findings indicate that competition with hatchery chum salmon contributed to the low productivity and abundance of Norton Sound chum salmon, which includes several stocks that are classified as Stocks of Concern by the State of Alaska. This study provides new evidence indicating that large-scale hatchery production may influence body size, age-at-maturation, productivity and abundance of a distant wild salmon population.

Environmental Biology of Fishes↗
USGS2025

Multi-species telemetry quantifies current and future efficacy of a remote marine protected area

Large-scale marine protected areas (LSMPAs; > 1000 km 2 ) provide important refuge for large mobile species, but most do not encompass species' ranges. To better understand current and future LSMPA value, we concurrently tracked nine species (seabirds, cetaceans, pelagic fishes, manta rays, reef sharks) at Palmyra Atoll and Kingman Reef (PKMPA) in the U.S. Pacific Islands Heritage Marine National Monument. PKMPA and the U.S. Exclusive Economic Zone encompassed 39% and 54% of species movements ( n = 83; tracking duration range: 0.5–350 days), respectively. Species distribution models indicated 73% of PKMPA contained highly suitable habitat. Under two projected future scenarios (SSP 1–2.6, “Sustainability”; SSP 3–7.0, “Rocky Road”), strong sea surface temperature gradients initially could cause abrupt oceanic change resulting in predicted habitat loss in 2040–2050, followed by an equilibrium response and regained habitat by 2090–2100. Current and future suitable habitats were available adjacent to PKMPA, suggesting that increased MPA size could enhance protection. Our three-tiered approach combining animal tracking with publicly available remote sensing data and future projected environmental scenarios could be used to design, study, and monitor protected areas throughout the world. Holistic approaches that encompass diverse species and habitat use can enhance assessments of protected area designs. Animal telemetry and remote sensing may be helpful for ascertaining the extent to which other MPAs protect large mobile species in the future.

Kingman Reef, Palmyra Atoll, U.S. Pacific Islands ↗
USGS2001

Establishment of the green mussel, Perna viridis (Linnaeus 1758) (Mollusca: Mytilidae) on the West Coast of Florida

In 1999, the green mussel, Perna viridis, was first observed in Tampa Bay, Florida. This was the first reported occurrence of this Indo-Pacific marine bivalve in North America. The mussels found in Tampa Bay were confirmed to be P. viridis based on both morphological and genetic characteristics. Since the initial discovery, surveys in Tampa Bay and on the west coast of Florida have documented the growth, recruitment, and range expansion of P. viridis. From November 1999 to July 2000, the mean shell length of a Tampa Bay population increased from 49.0 mm to 94.1 mm, an increase of 97%. Populations of P. viridis are successfully reproducing in Tampa Bay. Recruitment was observed on sampling plates in May and continued through July 2000. The full extent of mussel colonization is not clear, but mussels were found outside Tampa Bay in St. Petersburg, Florida, south to Venice. Based on these studies it is evident that P. viridis has successfully invaded Tampa Bay and the west coast of Florida. The long-term impact of P. viridis on native communities off the west coast of Florida cannot be predicted at this time.

Journal of Shellfish Research↗
USGS2025

Appendix B: Patterns of bull trout Salvelinus confluentus demography, life history, abundance, and trends in the Lewis River

Declines in the distribution and abundance of bull trout ( Salvelinus confluentus ) across much of the historical range in the Pacific Northwest region of Canada and the United States have been well documented (Post and Johnston 2002; Rieman et al. 1997). Recent estimates of population trends appear to vary considerably across regions with large numbers of migratory and resident populations exhibiting substantial declines in adult abundance (Al-Chokhachy et al. 2016; Kovach et al. 2018), whereas others remain stable or potentially increasing (Erhardt and Scarnecchia 2014; Meyer et al. 2014). For example, 61% of the core populations in Alberta, Canada, are considered declining, and 39% are stable or increasing (Alberta Sustainable Resource Development 2012). The variability in population status and trends highlights the importance of population-specific data. Much of our understanding of bull trout life history has stemmed from a few, well-studied populations, and continuing to improve our knowledge of the variability in life-history expressions (e.g., Starcevich et al. 2012) can support directing local and regional conservation efforts (sensu Schindler et al. 2010). Here, we consider the life history, demographic patterns, and assess potential threats for an adfluvial population of bull trout in the upper Lewis River basin in Washington, USA. We synthesized recent monitoring efforts and field studies to refine our understanding of bull trout life-history expressions (i.e., migration patterns), demographics, and genetic status. We further evaluated the potential threats of brook trout ( S. fontinalis ), a species that is not native to the Lewis River, but which was recently documented in bull trout monitoring efforts (Al-Chokhachy et al. 2024). Our specific objectives included evaluating: (1) trends in size structure of subadults and adult bull trout (2014 – 2024); (2) patterns of adult migration and life-history and climate drivers of migration patterns (2011 – 2024); (3) the within-year temporal patterns of bull trout and coho salmon ( Oncorhynchus kisutch ) spawning and superimposition of bull trout redds by spawning coho salmon (2024); (4) temporal trends in abundance for adult and juvenile bull trout from annual monitoring methods (2008 – 2024); and (5) the current (2024) extent of non-native brook trout in wetland habitat adjacent to Yale Lake.

Washington↗
USGS2017

Bioenergetics models to estimate numbers of larval lampreys consumed by smallmouth bass in Elk Creek, Oregon

Nonnative fishes have been increasingly implicated in the decline of native fishes in the Pacific Northwest. Smallmouth Bass Micropterus dolomieu were introduced into the Umpqua River in southwest Oregon in the early 1960s. The spread of Smallmouth Bass throughout the basin coincided with a decline in counts of upstream-migrating Pacific Lampreys Entosphenus tridentatus . This suggested the potential for ecological interactions between Smallmouth Bass and Pacific Lampreys, as well as freshwater-resident Western Brook Lampreys Lampetra richardsoni . To evaluate the potential effects of Smallmouth Bass on lampreys, we sampled diets of Smallmouth Bass and used bioenergetics models to estimate consumption of larval lampreys in a segment of Elk Creek, a tributary to the lower Umpqua River. We captured 303 unique Smallmouth Bass (mean: 197 mm and 136 g) via angling in July and September. We combined information on Smallmouth Bass diet and energy density with other variables (temperature, body size, growth, prey energy density) in a bioenergetics model to estimate consumption of larval lampreys. Larval lampreys were found in 6.2% of diet samples, and model estimates indicated that the Smallmouth Bass we captured consumed 925 larval lampreys in this 2-month study period. When extrapolated to a population estimate of Smallmouth Bass in this segment, we estimated 1,911 larval lampreys were consumed between July and September. Although the precision of these estimates was low, this magnitude of consumption suggests that Smallmouth Bass may negatively affect larval lamprey populations.

Oregon↗
USGS2017

Diet, feeding patterns, and prey selection of subyearling Atlantic salmon (Salmo salar) and subyearling chinook salmon (Oncorhynchus tshawytscha) in a tributary of Lake Ontario

Since juvenile Atlantic salmon ( Salmo salar ) and Chinook salmon ( Oncorhynchus tshawytscha ) occupy a similar habitat in Lake Ontario tributaries, we sought to determine the degree of diet similarity between these species in order to assess the potential for interspecific competition. Atlantic salmon, an historically important but currently extirpated component of the Lake Ontario fish community, are the focus of a bi-national restoration effort. Presently this effort includes the release of hatchery produced juvenile Atlantic salmon in Lake Ontario tributaries. These same tributaries support substantial numbers of naturally reproduced juvenile Pacific salmonids including Chinook salmon. Subyearling Atlantic salmon and subyearling Chinook salmon had significantly different diets during each of the three time periods examined. Atlantic salmon fed slightly more from the benthos than from the drift and consumed mainly chirononmids (47.0%) and ephemeropterans (21.1%). The diet of subyearling Chinook salmon was more closely associated with the drift and consisted mainly of chironomids (60.2%) and terrestrial invertebrates (16.0%). Low diet similarity between subyearling Atlantic salmon and subyearling Chinook salmon likely minimizes competitive interactions for food between these species in Lake Ontario tributaries. However, the availability of small prey such as chironomids which comprise over 50% of the diet of each species, soon after emergence, could constitute a short term resource limitation. To our knowledge this is the first study of interspecific diet associations between these two important salmonid species.

Journal of Applied Ichthyology↗
USGS1985

Preliminary description of a Miocene zone of structural complexity, Port Moller and Stepovak Bay quadrangles, Alaska: A section in The United States Geological Survey in Alaska: Accomplishments during 1983

A zone of structural disruption and complexity along the Pacific coast margin of the Alaska Peninsula (fig. 41) may be related to the Alaska Peninsula and the Chugach terrane boundary. The best exposure of this zone is located on the east shore of Humpback Bay (figs. 42, 43; also Burk, 1965, pl. 8, fig. 4); other exposures are located on the east side of Ivanof Bay, the north and south sides of Lefthand Bay, and in other coastal localities in the area. In some places, such as on the Kupreanof Peninsula, it is not recognized. This zone may extend discontinuously for 110-160 km along the coast; the width of the zone varies from 0.5 to 1 km. Our current data and tentative interpretations are described here, pending completion of additional field research, laboratory, and office studies.

Alaska↗
USGS2023

Interactions among rainfall, fire, forbs and non-native grasses predict occupancy dynamics for the endangered Pacific pocket mouse (Perognathus longimembris pacificus) in a Mediterranean-type ecosystem

It is important to understand species-habitat relationships to implement effective adaptive management for rare species. However, it can be challenging to assess habitat associations and their relationships to abiotic stressors in dynamic habitats without the insights that can be gained from long-term monitoring. We report results from the first six years of extensive track tube monitoring of the largest two of three remaining extant populations of federally endangered Pacific pocket mouse ( Perognathus longimembris pacificus ) in a coastal Mediterranean-type ecosystem on Marine Corps Base, Camp Pendleton in southern California, USA. We used dynamic occupancy and structural equation modeling to assess potential drivers of population trends that included habitat, fire history, rainfall, disturbance, and the presence of other small mammals. We found that the variables that best predicted mouse occupancy were moderate to high forb and perennial herb cover (40–80%), and moderate to high open ground (20–70%) and low non-native grass cover (<20%), Non-native grass cover (>20%) was also a strong predictor of lower PPM colonization and increased extinction probabilities, with the extent of non-native grass cover being strongly influenced by annual rainfall and recency of fire. Our study adds to the growing literature on effects of invasive annual grasses on native species in Mediterranean-type ecosystems. We suggest that habitat management could be based upon promotion of open forb and perennial herb dominated habitats with reduction of non-native grasses by prescribed fire and other methods. These types of spatial and temporal monitoring programs can support land managers by creating a monitoring and management feedback loop. They can reveal landscape and environmental variables associated with species persistence, inform habitat management goals, and help managers to assess the success of management actions on populations of conservation concern.

California↗
USGS2011

Seismicity of the Earth 1900-2010 eastern margin of the Australia plate

The eastern margin of the Australia plate is one of the most seismically active areas of the world due to high rates of convergence between the Australia and Pacific plates. In the region of New Zealand, the 3,000 km long Australia-Pacific plate boundary extends from south of Macquarie Island to the southern Kermadec Island chain. It includes an oceanic transform (the Macquarie Ridge), two oppositely verging subduction zones (Puysegur and Hikurangi), and a transpressive continental transform, the Alpine Fault through South Island, New Zealand. Since 1900, there have been 15 M7.5+ earthquakes recorded near New Zealand. Nine of these, and the four largest, occurred along or near the Macquarie Ridge, including the 1989 M8.2 event on the ridge itself, and the 2004 M8.1 event 200 km to the west of the plate boundary, reflecting intraplate deformation. The largest recorded earthquake in New Zealand itself was the 1931 M7.8 Hawke's Bay earthquake, which killed 256 people. The last M7.5+ earthquake along the Alpine Fault was 170 years ago; studies of the faults' strain accumulation suggest that similar events are likely to occur again.

Open-File Report↗
USGS1976

Water resources of Lincoln County coastal area, Oregon

The Lincoln County coastal area is underlain by Tertiary volcanic and sedimentary rocks of low permeability that store only a small volume of the annual precipitation which averages 68 inches (1,730 millimeters). Consequently, the Tertiary units yield small quantities of water to wells and furnish little ground-water discharge to maintain the base flow of streams. Although streamflow is normally abundant during the wet season, flow decreases greatly during summer when needed most. Quaternary marine terrace deposits of semiconsolidated sand border the western part of the area and are the most productive aquifers. Several wells drilled into the Quaternary deposits are among the highest producing wells of the area, with yields of 25 to 60 gallons per minute (1.6 to 3.8 liters per second). The Siletz River Volcanics is one of the better aquifers in the area and generally yields water in volumes sufficient for domestic use. The average well drilled into these rocks yields 5 to 10 gallons per minute (0.3 to 0.6 liters per second). Locally, this formation is quite permeable and has a producing well in the study area, with a yield of 120 gallons per minute (7.6 liters per second). Other volcanic rocks of small areal extent and largely untested, are the basalts near Depoe Bay, Cape Foulweather, Yachats, and Cape Perpetua. Wells drilled in January 1976 near Depoe Bay indicate that as much as 125 gal/min (10 L/s) of water can be obtained from wells drilled into the basalt. Tertiary marine sedimentary rocks of siltstone and sandstone are widespread throughout the area. Yields of wells drilled in these rocks are generally low (less than 5 gallons per minute, or 0.3 liters per second), and many wells in these formations produce no usable quantities of ground water. Approximately 5,000,000 acre-feet (6,000 cubic hectometers) of water discharges annually into the Pacific Ocean from all streams along the Lincoln County coast. About 85 percent of the annual streamflow occurs from November through April. Minimum streamflaws occur from August through October when, at times, as little as 450 acre-feet (55 hectometers) per day flows from all streams. Most of the ground water, with the exception of water from some wells drilled in the marine siltstone and sandstone, contains relatively small concentrations of dissolved minerals. Wells that tap the marine deposits at low altitudes have high concentrations of dissolved minerals, particularly sodium and chloride. In general, analyses of water from the 14 streams sampled in Lincoln County show very good chemical quality. The iron content of Depoe and Thiel Creeks is above the Environmental Protection Agency's recommended limit of 0.3 milligrams per liter for drinking water. Annual water use totals 6.7 billion gallons, which is less than 0.5 percent of runoff. About 70 percent of the use is for industrial purposes at one lumber products mill, about 25 percent is for public supplies, and less than 5 percent for irrigation. Water supplies for all municipalities in Lincoln County currently (1975) are obtained from surface-water sources. Because of rapid economic development of the coastal area, it is expected that additional water will be needed in the future. Additional water can be supplied (1) by reservoirs on major streams; (2) by the expansion, in some locations, of present surface-water facilities on small streams; and (3) locally, by an additional small volume of supplemental water from ground-water sources.

Oregon↗
USGS1995

Ground-water flow and water quality in the sand aquifer of Long Beach Peninsula, Washington

This report describes an investigation of ground-water flow and water quality in the sand aquifer of the Long Beach Peninsula. The peninsula is located in the southwestern corner of the State of Washington, is about 27 miles long, and has an average width of about 1.5 miles. It is surrounded by seawater, by the Pacific Ocean on the west and Willapa Bay on the east. Water supplies on the peninsula are derived mostly from a local water-table aquifer composed largely of sand. The recent growth of population on the peninsula and the projected future growth have created concerns about the quantity and quality of the ground-water resource. Some issues include declining ground-water levels from increased pumpage, and ground-water contamination from seawater intrusion, pesticides or fertilizers from cranberrygrowing areas, and septic-system effluent. The ground-water system of the Long Beach Peninsula consists of a sand aquifer with some lenses of silt and clay that may act as confining beds in local areas. Data are lacking or inconsistent to define a confining bed that extends throughout the peninsula. Hydraulic conductivity calculated from slug tests in 58 shallow wells ranged from 10 to 37 feet per day with a median of 22 feet per day. Average annual ground-water recharge by infiltration and percolation of precipitation is estimated to be about 58 inches or 111,000 acre-feet, which is 72 percent of the average annual precipitation of 80 inches. Average annual ground-water discharge is estimated to be about 30,200 acre-feet to the Pacific Ocean, 56,000 acre-feet to Willapa Bay, and 24,800 acre-feet to surface-water drainage channels. Ground-water movement is generally perpendicular to the spine of the peninsula. A ground-water divide occurs along a north-south line and ground water flows west or east from the divide toward the Pacific Ocean or Willapa Bay. There does not appear to have been any long-term decline of the water table of the sand aquifer from 1974-92. Ground-water levels measured at three east-west cross sections in 1974-75 were at about the same altitude as water levels measured in 1992. Relatively accurate individual regression relations were developed at 45 wells with ground-water altitude as a response variable and cumulative precipitation for 4 months as an explanatory variable. The average coefficient of determination for all individual relations was 0.77, with a range of 0.11 to 0.89. Some empirical frequency or probability relations for precipitation and ground-water levels were used to estimate how often the maximum water levels measured in this study would be expected to occur in the future. These water levels reflected the lower-than-average precipitation that occurred during the study. Assuming that the annual maximum precipitation for 4 consecutive months is random and independent, the historical record of precipitation is representative of the future distribution of precipitation, and the relation between precipitation and water levels is accurate and stationary; a probability analysis of the historical record indicates that in any one year in the future there is a probability of 70 percent that the maximum water levels measured in wells during the winter of 1991-92 would be equaled or exceeded. The shallow ground water had generally low dissolved-solids concentrations in July 1992, with a median concentration of 92 milligrams per liter (mg/L) and a range of 56 to 218 mg/L. Sodium was the dominant cation and bicarbonate was the dominant anion. The distribution of hardness of the water samples was 84 percent with soft water and 16 percent with moderately hard water. The water quality of the shallow ground water was generally good, with a few small to moderate problems. A natural problem is locally high concentrations of dissolved iron. About 30 percent of the water samples had dissolved-iron concentrations of greater than 0.3 mg/L, which is the secondary maximum contaminant level established by the U.S. Environmental Protection Agency. No appreciable amount of seawater has intruded into the sand aquifer. The samples of shallow ground water collected in July 1992 had a median chloride concentration of 15 mg/L and a maximum concentration of 52 mg/L. The heavy average annual precipitation of about 80 inches, large average annual ground-water recharge of about 58 inches or 111,000 acre-feet, and small ground-water withdrawal rate (about 780 acre-feet per year in 1992) combine to maintain a thick freshwater lens of ground water that prevents seawater intrusion throughout the year. Agricultural activities do not appear to have appreciably affected the quality of shallow ground water on the Long Beach Peninsula. The concentration of nitrate in ground water was not significantly higher near cranberry-growing areas, and no sample of ground water or surface water had concentrations of selected pesticides or associated compounds that were above the analytical detection limits. Of the seven ground-water samples in which bacteria were detected, only one sample appeared to be related to agriculture; that sample was from a well located in an area where cattle graze for part of the year. Septic systems probably caused an increase in the concentration of nitrate in shallow ground water in areas of higher population density. Concentrations of nitrate were significantly related to population density. However, the concentrations were not generally high; median concentrations of nitrate increased from less than 0.05 mg/L in areas of low population density to 0.74 mg/L in areas of high density. Septic systems did not cause regional bacterial contamination of the ground water. Bacteria were detected in seven ground-water samples; however, only two of those samples were from wells that are close to septic systems. A limited amount of historical water-quality data is available for the peninsula; therefore, it is difficult to assess long-term changes. From 1968-92, chloride concentrations and values of specific conductance appear to have remained stable. Likewise, it appears that nitrate concentrations did not change from 1987-92.

Washington↗
USGS2026

Migration water temperature and heat stress assessments in western Alaska Chinook salmon overlapping the 2019 heatwave

Chinook salmon population declines span their geographic range with climate hypothesized as a major driver. Concerns of warming freshwater temperatures in their northern range gained urgency during 2019 when a heatwave coincided with premature mortality. This study examined heat stress during the 2019 heatwave compared to subsequent years and described water temperatures in western Alaska to understand the degree to which freshwater temperatures may be a stressor. Heat stress was prevalent among Chinook salmon captured in the 2019 heatwave (Kuskokwim tributaries: 90% in Kwethluk and 63% Takotna river), and variable in subsequent years (∼8% to 60% across Kuskokwim tributaries and Norton Sound rivers). A review of water temperature data indicated that potentially stressful temperatures (≥18 °C) were most common and prolonged in the Yukon River, moderately common and prolonged in the Kuskokwim River, and relatively rare in the Norton Sound region. Water temperatures in 2019 broke several records for overall maximum and frequency of temperatures ≥ 18 °C. Migration water temperatures and heat stress in northern Pacific salmon habitats vary more widely than previously recognized (up to 25 °C).

Alaska↗
USGS2013

Atmospheric rivers as drought busters on the U.S. west coast

Atmospheric rivers (ARs) have, in recent years, been recognized as the cause of the large majority of major floods in rivers all along the U.S. West Coast and as the source of 30%–50% of all precipitation in the same region. The present study surveys the frequency with which ARs have played a critical role as a common cause of the end of droughts on the West Coast. This question was based on the observation that, in most cases, droughts end abruptly as a result of the arrival of an especially wet month or, more exactly, a few very large storms. This observation is documented using both Palmer Drought Severity Index and 6-month Standardized Precipitation Index measures of drought occurrence for climate divisions across the conterminous United States from 1895 to 2010. When the individual storm sequences that contributed most to the wet months that broke historical West Coast droughts from 1950 to 2010 were evaluated, 33%–74% of droughts were broken by the arrival of landfalling AR storms. In the Pacific Northwest, 60%–74% of all persistent drought endings have been brought about by the arrival of AR storms. In California, about 33%–40% of all persistent drought endings have been brought about by landfalling AR storms, with more localized low pressure systems responsible for many of the remaining drought breaks.

California;Oregon;Washington↗
USGS2023

A characterization of the deep-sea coral and sponge community along the Oregon Coast using a remotely operated vehicle on the EXPRESS 2022 expedition

Deep-sea coral and sponge (DSCS) communities serve as essential fish habitat (EFH) by providing shelter and nursery habitat, increasing diversity, and increasing prey availability (Freese and Wing, 2003; Bright, 2007; Baillon et al., 2012; Henderson et al., 2020). Off the U.S. West Coast, threats to these long-lived, fragile organisms from bottom contact fishing gear, potential offshore renewable energy development, and ocean warming and acidification have been the subject of recent research (Gomez et al., 2018; Salgado et al., 2018; Yoklavich, et al., 2018; Gugliotti et al., 2019). Other DSCS studies have reported new species (Yoklavich and Love, 2005), analyzed species distribution and abundance (Tissot et al., 2006, Watters et al., 2022), developed predictive distribution models (Huff et al., 2013; Rooper et al., 2017; Kreidler, 2020), and discovered medicinal uses for corals and sponges (Essack et al., 2011; Shrestha et al., 2018). Due to the vast area of unexplored seafloor within the territorial waters and the U.S. exclusive economic zone (EEZ; 12-200 nautical miles off the coast) and the technological requirements and expense of deep-sea research, there is still much to learn about the distributions and biology of DSCS. This information is critical to resource managers for effective conservation and management of DSCS habitats. In order to minimize the adverse impacts of fishing on EFH, the Pacific Fishery Management Council (PFMC) and National Marine Fisheries Service (NMFS) designated several seafloor habitat areas as EFH conservation areas (EFHCA), first in 2006 (as part of Amendment 19 to the Pacific coast groundfish fishery management plan) and then again in 2020 (as part of Amendment 28). These areas are closed to bottom trawl fishing at a minimum, and in some cases to all bottom contact fishing gears. In addition to protections afforded by EFH-related regulations, the National Marine Sanctuary Program prohibits certain non-fishing activities within areas designated as national marine sanctuaries, such as oil and gas exploration or extraction, cable laying, and other forms of seabed alteration or construction that disturb benthic communities. NOAA’s Deep-Sea Coral and Research Technology Program (DSCRTP) began a 4-yr funding initiative for the U.S. West Coast in 2017. The goals of the West Coast Deep-Sea Coral Initiative (WCDSCI) were to: 1) gather baseline information on areas subject to fishing regulation changes prior to the implementation of Amendment 28; 2) improve our understanding of known DSCS bycatch “hot spots”; and 3) explore and assess DSCS resources within NOAA National Marine Sanctuaries with emphasis on areas of sanctuary resource protection and management concerns. As part of the WCDSCU, an 11-day expedition (3 Sep – 13 Sep 2022) was launched from the NOAA Ship Bell M. Shimada, beginning and ending in Newport, OR. The science team assembled for this cruise were members of the EXpanding Pacific Research and Exploration of Submerged Systems (EXPRESS) campaign, which brings together researchers from federal and nonfederal institutions to collaborate on scientific expeditions targeting the deepwater areas off California, Oregon, and Washington. EXPRESS supports researchers leveraging funding, resources, personnel, and expertise to accomplish more science than would have been possible by a single entity alone. The 2022 expedition included research partners from National Marine Fisheries Service (NMFS) Southwest Fisheries Science Center (SWFSC) and Northwest Fisheries Science Center (NWFSC), Bureau of Ocean Energy Management (BOEM), U.S. Geological Survey (USGS), Pacific Fisheries Management Council Habitat Committee, and Woods Hole Oceanographic Institution.

Report↗
USGS2013

Trends and shifts in streamflow in Hawaii, 1913-2008

This study addresses a need to document changes in streamflow and base flow (groundwater discharge to streams) in Hawai'i during the past century. Statistically significant long-term (1913-2008) downward trends were detected (using the nonparametric Mann-Kendall test) in low-streamflow and base-flow records. These long-term downward trends are likely related to a statistically significant downward shift around 1943 detected (using the nonparametric Pettitt test) in index records of streamflow and base flow. The downward shift corresponds to a decrease of 22% in median streamflow and a decrease of 23% in median base flow between the periods 1913-1943 and 1943-2008. The shift coincides with other local and regional factors, including a change from a positive to a negative phase in the Pacific Decadal Oscillation, shifts in the direction of the trade winds over Hawai'i, and a reforestation programme. The detected shift and long-term trends reflect region-wide changes in climatic and land-cover factors. A weak pattern of downward trends in base flows during the period 1943-2008 may indicate a continued decrease in base flows after the 1943 shift. Downward trends were detected more commonly in base-flow records than in high-streamflow, peak-flow, and rainfall records. The decrease in base flow is likely related to a decrease in groundwater storage and recharge and therefore is a valuable indicator of decreasing water availability and watershed vulnerability to hydrologic changes. Whether the downward trends will continue is largely uncertain given the uncertainty in climate-change projections and watershed responses to changes.

Hawai'i↗
USGS2007

S-33 constraints on the seawater sulfate contribution in modern seafloor hydrothermal vent sulfides

Sulfide sulfur in mid-oceanic ridge hydrothermal vents is derived from leaching of basaltic-sulfide and seawater-derived sulfate that is reduced during high temperature water rock interaction. Conventional sulfur isotope studies, however, are inconclusive about the mass-balance between the two sources because 34S/32S ratios of vent fluid H2S and chimney sulfide minerals may reflect not only the mixing ratio but also isotope exchange between sulfate and sulfide. Here, we show that high-precision analysis of S-33 can provide a unique constraint because isotope mixing and isotope exchange result in different ??33S (?????33S-0.515 ??34S) values of up to 0.04??? even if ??34S values are identical. Detection of such small ??33S differences is technically feasible by using the SF6 dual-inlet mass-spectrometry protocol that has been improved to achieve a precision as good as 0.006??? (2??). Sulfide minerals (marcasite, pyrite, chalcopyrite, and sphalerite) and vent H2S collected from four active seafloor hydrothermal vent sites, East Pacific Rise (EPR) 9-10??N, 13??N, and 21??S and Mid-Atlantic Ridge (MAR) 37??N yield ??33S values ranging from -0.002 to 0.033 and ??34S from -0.5??? to 5.3???. The combined ??34S and ??33S systematics reveal that 73 to 89% of vent sulfides are derived from leaching from basaltic sulfide and only 11 to 27% from seawater-derived sulfate. Pyrite from EPR 13??N and marcasite from MAR 37??N are in isotope disequilibrium not only in ??34S but also in ??33S with respect to associated sphalerite and chalcopyrite, suggesting non-equilibrium sulfur isotope exchange between seawater sulfate and sulfide during pyrite precipitation. Seafloor hydrothermal vent sulfides are characterized by low ??33S values compared with biogenic sulfides, suggesting little or no contribution of sulfide from microbial sulfate reduction into hydrothermal sulfides at sediment-free mid-oceanic ridge systems. We conclude that 33S is an effective new tracer for interplay among seawater, oceanic crust and microbes in subseafloor hydrothermal sulfur cycles. ?? 2006 Elsevier Inc. All rights reserved.

Geochimica et Cosmochimica Acta↗