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At least 523 records · Page 29Linked to original sources

USGS2006

Groundwater dolocretes from the Upper Triassic of the Paris Basin, France: A case study of an arid, continental diagenetic facies

Thick dolomite-cemented horizons (dolocretes) occur within a fluvial sandstone-mudstone sequence of Late Triassic age in the western part of the Paris Basin, France. Two types of dolomites can be distinguished: (a) nodular dolomitic beds less than a few metres thick, which formed within mottled overbank siltstones and mudstones; and (b) massive dolomite up to 16 m thick, which occurs in coarse grained channel sandstones and conglomerates. The majority of the dolomite consists of a finely crystalline groundmass of dolomicrospar and, less commonly, dolomicrite. Glaebules, irregular spar-filled cracks, spheroidal dolomite, silicification and vuggy porosity are locally abundant in the massive dolomite. In contrast, biologically induced micromorphological features such as rhizocretions and alveolar-septal fabrics were observed in the thin, nodular dolomite beds. The dolomite is near stoichiometric, well ordered and non-ferroan. 18O values range from −7·7 to −0·4%o PDB and 18O values range from −5·1 to + 1·8%0 PDB and no obvious difference in the stable isotopic composition between both types of dolomites was observed. Sr isotope ratios range from 0·7101 to 0·7126 and are invariably higher than the contemporary Triassic sea water. A vadose—pedogenic origin for the thin dolocrete layers is indicated by the occurrence of rhizocretions and other biological structures. Several features, however, argue against a pedogenic origin for the massive carbonates, most notably the absence of biologically induced structures, the occurrence in coarse grained channel (and not overbank) deposits, and the great thickness. These units are thus interpreted as groundwater in origin. Phreatic calcretes of Quaternary age, widespread in inland Australia, are regarded as a modern analogue for the Triassic Paris Basin dolocretes. Petrographic observations argue in favour of primary (proto)dolomite precipitation, although early diagenetic replacement of calcite by (proto)dolomite cannot be ruled out. Strontium and carbon isotope data of early diagenetic dolocrete cements and oxygen isotope data of early diagenetic silica indicate an entirely non-marine, continental origin for the groundwaters. The poorly ordered and non-stoichiometric protodolomite probably underwent stabilization upon further burial resulting in a near-stoichiometric, well ordered dolomite that clearly lacks evidence for pervasive recrystallization.

Paris↗

USGS2015

California State Waters Map Series — Offshore of Bolinas, California

Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology. The Offshore of Bolinas map area is located in northern California, on the Pacific Coast of Marin County about 10 kilometers north of the Golden Gate. The town of Bolinas, named after a local indigenous tribe, is the largest population center along this section of coast, with a population of approximately 1,600 people. Bolinas is situated at the end of a southeast-trending terrain on the west side of the San Andreas Fault that also protects a natural harbor. The harbor lies in Bolinas Lagoon, which is separated from Bolinas Bay by a spit. The coastal lands within the Offshore of Bolinas map area lie entirely within the Point Reyes National Seashore, which limits development and allows existing ranching and farming to continue. The Offshore of Bolinas map area lies offshore of the northwest-trending Coast Ranges, which lie east of, and are roughly parallel to, the San Andreas Fault Zone. The western margin of North America is the only continental margin in the world delineated largely by transform faults such as the San Andreas Fault. The coastal geomorphology is controlled by late Pleistocene to Holocene slip along the fault. Bolinas Bay and Lagoon have formed where a regional depression along the fault zone intersects the coast. A northward bend in the San Andreas Fault to the north, combined with right-lateral movement, has caused regional extension and the formation of a sediment basin on the continental shelf in, and southeast of, Bolinas Bay. With the exception of the area adjacent to Bolinas Bay, the coast in the map area consists of high coastal bluffs and vertical sea cliffs. The uplifted headland upon which the town of Bolinas is situated is part of a larger uplifted area that includes exposed bedrock offshore. Uplift in this map area has resulted in relatively shallow depths within California’s State Waters (0 to 40 m) and, thus, little accommodation space for sediment accumulation. Sediment is found in the extensional basin southeast of Bolinas, as well as on the shelf offshore of uplifted coastal areas, where, within California’s State Waters, depths can exceed 40 m. Wave energy keeps the uplifted bedrock areas clear of sediment, and rippled sediment in the outer shelf indicates some mobility. Coastal sediment transport in the Offshore of Bolinas map area is characterized by north-to-south littoral transport of sediment that is derived mainly from ephemeral streams and local coastal erosion. Beyond California’s State Waters, canyons that incise the slope have been disconnected from coastal streams by rising sea level, which has risen about 125 m since the lowstand associated with the Last Glacial Maximum about 18,000 to 20,000 years ago. In the map area, no major submarine canyons extend up past the shelf break and into the nearshore to receive littoral drift. The coastline in the map area is characterized as high risk because of its steep cliffs and large-scale landsliding. The sand spit that separates Bolinas Lagoon from Bolinas Bay is highly developed, and its homes are at risk during storms, especially those from the south. The benthic species observed in the Offshore of Bolinas map area are natives of the cold-temperate biogeographic zone named either the “Oregonian province” or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, an eastern limb of the North Pacific subtropical gyre that flows from Oregon to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 425 km south of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off central California has seen a warming over the last 50 years that is driving an ecosystem shift from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of Bolinas map area, which lies within the Shelf (continental shelf) megahabitat, range from, in the nearshore, sandy seafloor in the southeast and significant rocky outcrops that support kelp-forest communities in the northwest to, in deeper water, rocky-reef communities. Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. The large extent of exposed inner shelf bedrock in the northeast supports large forests of “bull kelp,” which is well adapted for high wave-energy environments. Common fish species found in the kelp beds and rocky reefs include lingcod and various species of greenling and rockfish.

California↗

USGS1999

Processes governing phytoplankton blooms in estuaries. II: The role of horizontal transport

The development and distribution of phytoplankton blooms in estuaries are functions of both local conditions (i.e. the production-loss balance for a water column at a particular spatial location) and large-scale horizontal transport. In this study, the second of a 2-paper series, we use a depth-averaged hydrodynamic-biological model to identify transport-related mechanisms impacting phytoplankton biomass accumulation and distribution on a system level. We chose South San Francisco Bay as a model domain, since its combination of a deep channel surrounded by broad shoals is typical of drowned-river estuaries. Five general mechanisms involving interaction of horizontal transport with variability in local conditions are discussed. Residual (on the order of days to weeks) transport mechanisms affecting bloom development and location include residence time/export, import, and the role of deep channel regions as conduits for mass transport. Interactions occurring on tidal time scales, i.e. on the order of hours) include the phasing of lateral oscillatory tidal flow relative to temporal changes in local net phytoplankton growth rates, as well as lateral sloshing of shoal-derived biomass into deep channel regions during ebb and back into shallow regions during flood tide. Based on these results, we conclude that: (1) while local conditions control whether a bloom is possible, the combination of transport and spatial-temporal variability in local conditions determines if and where a bloom will actually occur; (2) tidal-time-scale physical-biological interactions provide important mechanisms for bloom development and evolution. As a result of both subtidal and tidal-time-scale transport processes, peak biomass may not be observed where local conditions are most favorable to phytoplankton production, and inherently unproductive areas may be regions of high biomass accumulation.

Marine Ecology Progress Series↗

USGS2014

Nutrient additions to mitigate for loss of Pacific salmon: consequences for stream biofilm and nutrient dynamics

Mitigation activities designed to supplement nutrient and organic matter inputs to streams experiencing decline or loss of Pacific salmon typically presuppose that an important pathway by which salmon nutrients are moved to fish (anadromous and/or resident) is via nutrient incorporation by biofilms and subsequent bottom-up stimulation of biofilm production, which is nutrient-limited in many ecosystems where salmon returns have declined. Our objective was to quantify the magnitude of nutrient incorporation and biofilm dynamics that underpin this indirect pathway in response to experimental additions of salmon carcasses and pelletized fish meal (a.k.a., salmon carcass analogs) to 500-m reaches of central Idaho streams over three years. Biofilm standing crops increased 2–8-fold and incorporated marine-derived nutrients (measured using 15 N and 13 C) in the month following treatment, but these responses did not persist year-to-year. Biofilms were nitrogen (N) limited before treatments, and remained N limited in analog, but not carcass-treated reaches. Despite these biofilm responses, in the month following treatment total N load was equal to 33–47% of the N added to the treated reaches, and N spiraling measurements suggested that as much as 20%, but more likely 2–3% of added N was taken up by microbes. Design of biologically and cost-effective strategies for nutrient addition will require understanding the rates at which stream microbes take up nutrients and the downstream distance traveled by exported nutrients.

Idaho↗

USGS2012

The United States National Climate Assessment - Alaska Technical Regional Report

The Alaskan landscape is changing, both in terms of effects of human activities as a consequence of increased population, social and economic development and their effects on the local and broad landscape; and those effects that accompany naturally occurring hazards such as volcanic eruptions, earthquakes, and tsunamis. Some of the most prevalent changes, however, are those resulting from a changing climate, with both near term and potential upcoming effects expected to continue into the future. Alaska's average annual statewide temperatures have increased by nearly 4°F from 1949 to 2005, with significant spatial variability due to the large latitudinal and longitudinal expanse of the State. Increases in mean annual temperature have been greatest in the interior region, and smallest in the State's southwest coastal regions. In general, however, trends point toward increases in both minimum temperatures, and in fewer extreme cold days. Trends in precipitation are somewhat similar to those in temperature, but with more variability. On the whole, Alaska saw a 10-percent increase in precipitation from 1949 to 2005, with the greatest increases recorded in winter. The National Climate Assessment has designated two well-established scenarios developed by the Intergovernmental Panel on Climate Change (Nakicenovic and others, 2001) as a minimum set that technical and author teams considered as context in preparing portions of this assessment. These two scenarios are referred to as the Special Report on Emissions Scenarios A2 and B1 scenarios, which assume either a continuation of recent trends in fossil fuel use (A2) or a vigorous global effort to reduce fossil fuel use (B1). Temperature increases from 4 to 22°F are predicted (to 2070-2099) depending on which emissions scenario (A2 or B1) is used with the least warming in southeast Alaska and the greatest in the northwest. Concomitant with temperature changes, by the end of the 21st century the growing season is expected to lengthen by 15-25 days in some areas of Alaska, with much of that corresponding with earlier spring snow melt. Future projections of precipitation (30-80 years) over Alaska show an increase across the State, with the largest changes in the northwest and smallest in the southeast. Because of increasing temperatures and growing season length, however, increased precipitation may not correspond with increased water availability, due to temperature related increased evapotranspiration. The extent of snow cover in the Northern Hemisphere has decreased by about 10 percent since the late 1960s, with stronger trends noted since the late 1980s. Alaska has experienced similar trends, with a strong decrease in snow cover extent occurring in May. When averaged across the State, the disappearance of snow in the spring has occurred from 4 to 6 days earlier per decade, and snow return in fall has occurred approximately 2 days later per decade. This change appears to be driven by climate warming rather than a decrease in winter precipitation, with average winter temperatures also increasing by about 2.5°F. The extent of sea ice has been declining, as has been widely published in both national and scientific media outlets, and is projected to continue to decline during this century. The observed decline in annual sea ice minimum extent (September) has occurred more rapidly than was predicted by climate models and has been accompanied by decreases in ice thickness and in the presence of multi-year ice. This decrease was first documented by satellite imagery in the late 1970s for the Bering and Chukchi Seas, and is projected to continue, with the potential for the disappearance of summer sea ice by mid- to late century. A new phenomenon that was not reported in previous assessments is ocean acidification. Uptake of carbon dioxide (CO2) by oceans has a significant effect on marine biogeochemistry by reducing seawater pH. Ocean acidification is of particular concern in Alaska, because cold sea water absorbs CO2 more rapidly than warm water, and a decrease in sea ice extent has allowed increased sea surface exposure and more uptake of CO2 into these northern waters. Ocean acidification will likely affect the ability of organisms to produce and maintain shell material, such as aragonite or calcite (calcium carbonate minerals structured from carbonate ions), required by many shelled organism, from mollusks to corals to microscopic organisms at the base of the food chain. Direct biological effects in Alaska further along the food chain have yet to be studied and may vary among organisms. Some of the potentially most significant changes to Alaska that could result from a changing climate are the effects on the terrestrial cryosphere - particularly glaciers and permafrost. Alaskan glaciers are changing at a rapid rate, the primary driver appearing to be temperature. Statewide, glaciers lost 13 cubic miles of ice annually from the 1950s to the 1990s, and that rate doubled in the 2000s. However, like temperature and precipitation, glacier ice loss is not spatially uniform; most glaciers are losing mass, yet some are growing (for example Hubbard Glacier in southeast Alaska). Alaska glaciers with the most rapid loss are those terminating in sea water or lakes. With this increasing rate of melt, the contribution of surplus fresh water entering into the oceans from Alaska's glaciers, as well as those in neighboring British Columbia, Canada, is approximately 20 percent of that contributed by the Greenland Ice Sheet. Permafrost degradation (that is, the thawing of ice-rich soils) is currently (2012) impacting infrastructure and surface-water availability in areas of both discontinuous and continuous ground ice. Over most of the State, the permafrost is warming, with increasing temperatures broadly consistent with increasing air temperatures. On the Arctic coastal plain of Alaska, permafrost temperatures showed some cooling in the 1950s and 1960s but have been followed by a roughly 5°F increase since the 1980s. Many areas in the continuous permafrost zone have seen increases in temperature in the seasonally active layer and a decrease in re-freezing rates. Changes in the discontinuous permafrost zone are initially much more observable due to the resulting thermokarst terrain (land surface formed as ice rich permafrost thaws), most notable in boreal forested areas. Climate warming in Alaska has potentially broad implications for human health and food security, especially in rural areas, as well as increased risk for injury with changing winter ice conditions. Additionally, such warming poses the potential for increasing damage to existing water and sanitation facilities and challenges for development of new facilities, especially in areas underlain by permafrost. Non-infectious and infectious diseases also are becoming an increasing concern. For example, from 1999 to 2006 there was a statistically significant increase in medical claims for insectbite reactions in five of six regions of Alaska, with the largest percentage increase occurring in the most northern areas. The availability and quality of subsistence foods, normally considered to be very healthy, may change due to changing access, changing habitats, and spoilage of meat in food storage cellars. These and other trends and potential outcomes resulting from a changing climate are further described in this report. In addition, we describe new science leadership activities that have been initiated to address and provide guidance toward conducting research aimed at making available information for policy makers and land management agencies to better understand, address, and plan for changes to the local and regional environment. This report cites data in both metric and standard units due to the contributions by numerous authors and the direct reference of their data.

Alaska↗

USGS2002

Multibeam bathymetry and selected perspective views of main part of Glacier Bay, Alaska

Glacier Bay is a diverse fjord ecosystem with multiple tidewater glaciers and complex biological, geological, and oceanographic patterns that vary greatly along its length. The bay was completely glaciated prior to the 1700's, and subsequently experienced the fastest glacial retreat recorded in historical times. As a result, some of the highest rates of glacial sedimentation and uplift are observed here. Glacier Bay is the deepest silled fjord in Alaska, with depths of over 450 meters. The variety of physical processes and depths creates many diverse habitats within a relatively small area. Mapping benthic (seafloor) habitats is thus crucial to understanding and managing Glacier Bay's complex marine ecosystem and the marine species therein. High-resolution multibeam mapping of the bay, funded jointly by USGS and the National Park System, provides an unprecedented new baseline for resource and habitat assessment. Full integration of the new data set will require additional ground-truthing data (sampling) and analysis. The USGS goal is to develop integrated geological and oceanographic habitat models for the marine benthos in Glacier Bay, as a step toward determining the habitat relationships of critical species and resources within the Park.

Alaska↗

USGS1998

The last interglaciation at Owens Lake, California; Core OL-92

Owens Lake, located at the eastern base of the central Sierra Nevada (Fig. 1), was the terminus of the Owens River prior to the lake's complete desiccation shortly after 1913 due to river diversion by the City of Los Angeles. During earlier wetter cycles, the lake overflowed to fill a series of downstream basins including China Lake Basin, Searles Valley, Panamint Valley, and ultimately, Death Valley (Smith and Street-Perrott, 1983). In 1992 the U.S. Geological Survey drilled a 323-m-deep core (OL-92) into Owens Lake sediments near the depocenter of the basin to obtain a continuous record of silty-clay sediment spanning the last 800,000 yrs. A multi-parameter reconnaissance study of the entire core (ca 7000-yr resolution), was reported in a 13-chapter summary volume (Smith and Bischoff, 1997). A document containing the numerical and other detailed forms of raw data collected by that volume's authors was prepared earlier (Smith and Bischoff, 1993). The reconnaissance study provided an approximate time-depth model for the entire core, based on radiocarbon dates from the top 31m, the Bishop Ash (759,000 yrs) at 304 m, ten within-Brunhes paleomagnetic excursions, and a compaction-corrected mass-accumulation rate of 51.4 g/cm/l000yr (Bischoff et al., 1997a). Application of this model to observed sediment parameters indicates that Owens Lake was saline, alkaline, and biologically productive at times of decreased water-flow, and was generally hydrologically flushed and relatively unproductive during times of increased water-flow. Grain size, abundance of CaCO 3 , organic carbon, clay mineralogy, cation-exchange capacity of the clay fraction, fossil pollen, fish, ostracodes, and diatoms (see summary by Smith et al., 1997) all show cyclic variation down the core. CaCO 3 abundance, in particular, strongly reflects an approximately 100 ka dominant cycle, characteristic of global ice-volume indicated by the MIS δ 18 O record. Four of the last five marine isotope terminations are clearly shown in the OL-92 record.

California↗

USGS2008

Trace fossils and sedimentary facies from a Late Cambrian‐Early Ordovician tide‐dominated shelf (Santa Rosita Formation, northwest Argentina): Implications for ichnofacies models of shallow marine successions

The Santa Rosita Formation is one the most widely distributed lower Paleozoic units of northwest Argentina. At the Quebrada del Salto Alto section, east of Purmamarca, Jujuy Province, it is represented by four sedimentary facies: thick‐bedded planar cross‐stratified quartzose sandstones (A), thin‐bedded planar cross‐stratified quartzose sandstones and mudstones (B), wave‐rippled sandstones and bioturbated mudstones (C), and black and greenish gray shales (D). Paleocurrent data, sandstone architecture, and sedimentary structures from faciès A and B indicate bipolar/bimodal paleoflows, suggesting the action of tidal currents. The succession is interpreted as that of a tide‐dominated shelf, with only secondary influence of wave processes. Trace fossils are restricted to facies B and C. The Cruziana ichnocoenosis is preserved on the soles of thin‐bedded planar cross‐stratified quartzose sandstones (faciès B). This ichnocoenosis consists of Conostichus isp., Cruziana omanica, C. semiplicata, C. cf. tortworthi, Cruziana isp. Helminthopsis abeli, Monomorphichnus bilinearis, M. multilineatus, Palaeophycus tubularis, Rusophycus carbonarias, R. latus , and R. isp. The occurrence of Cruziana semiplicata , C. omanica, C. cf. tortworthi , and Rusophycus latus supports a Late Cambrian‐Tremadoc age. Slabbing of Cruziana shows complex interactions between biologic and sedimentologic processes, and suggests a predominance of exhumed traces, washed out and recast by tractive sand deposition. Sandstone soles are densely packed with biogenic structures and exhibit distinctive clusters of Rusophycus isp. that most likely represent trilobite nesting burrows. The Cruziana ichnocoenosis records the resident fauna of a protected, lower intertidal to subtidal interbar setting. The Skolithos ichnocoenosis is represented by high to low density vertical burrows of Skolithos linearis , which extend downwards to the quartzose sandstone soles of faciès B and cross the Cruziana ichnocoenosis. The Skolithos ichnocoenosis represents colonization by suspension‐feeding organisms following a major change in environmental conditions, related to the migration of lower intertidal to subtidal sandwaves. The Planolites ichnocoenosis consists exclusively of Planolites montanus within mudstones overlying wave‐rippled sandstones (facies C). The Planolites ichnocoenosis records opportunistic colonization by inf aunal deposit feeders that mined the organic‐rich fine‐grained sediment during the waning phase of storms that scoured organic detritus from the sea bottom. The section records, from base to top, a Cruziana‐Skolithos ichnofacies zone, a Skolithos ichnofacies zone and an unbioturbated zone typified by the thick‐bedded cross‐stratified quartzose sandstone (fades A). This trend reflects progressively higher energy conditions linked to the establishment of a large sand wave complex. The presence of a mixed Cruziana‐Skolithos ichnofacies in the lower interval reflects changes in substrate and energy levels, rather than water depth. Accordingly, contrasting ichnocoenoses from interbars (Cruziana) and sandwaves (Skolithos) must be considered an example of ichnofacies controlled by local parameters instead of general bathymétrie trends. Conversely, the vertical replacement of the Cruziana ichnofacies by the Skolithos ichnofacies towards the middle interval of the section reflects the environmental changes associated with the transition between the intertidal and subtidal zones. As overall tidal energy increases from supratidal to subtidal settings, the Skolithos ichnofacies tends to occur seaward of the Cruziana ichnofacies in tide‐dominated shallow marine environments. Therefore, onshore‐offshore ichnofacies replacement in tide‐dominated shallow seas is opposite to that in wave‐dominated marine settings.

Ichnos: An International Journal for Plant and Ani↗

USGS2013

Anaerobic methane oxidation in low-organic content methane seep sediments

Sulfate-dependent anaerobic oxidation of methane (AOM) is the key sedimentary microbial process limiting methane emissions from marine sediments and methane seeps. In this study, we investigate how the presence of low-organic content sediment influences the capacity and efficiency of AOM at Bullseye vent, a gas hydrate-bearing cold seep offshore of Vancouver Island, Canada. The upper 8 m of sediment contains < 0.4 wt% total organic carbon (OC) and primarily consists of glacially-derived material that was deposited 14,900 to 15,900 yrs BP during the retreat of the late Quaternary Cordilleran Ice Sheet. We hypothesize this aged and exceptionally low-OC content sedimentary OM is biologically refractory, thereby limiting degradation of non-methane OM by sulfate reduction and maximizing methane consumption by sulfate-dependent AOM. A radiocarbon-based dissolved inorganic carbon (DIC) isotope mass balance model demonstrates that respired DIC in sediment pore fluids is derived from a fossil carbon source that is devoid of 14 C. A fossil origin for the DIC precludes remineralization of non-fossil OM present within the sulfate zone as a significant contributor to pore water DIC, suggesting that nearly all sulfate is available for anaerobic oxidation of fossil seep methane. Methane flux from the SMT to the sediment water interface in a diffusion-dominated flux region of Bullseye vent was, on average, 96% less than at an OM-rich seep in the Gulf of Mexico with a similar methane flux regime. Evidence for enhanced methane oxidation capacity within OM-poor sediments has implications for assessing how climate-sensitive reservoirs of sedimentary methane (e.g., gas hydrate) will respond to ocean warming, particularly along glacially-influenced mid and high latitude continental margins.

Geochimica et Cosmochimica Acta↗

USGS1998

Estimates of annual survival probabilities for adult Florida manatees ( Trichechus manatus latirostris )

The population dynamics of large, long-lived mammals are particularly sensitive to changes in adult survival. Understanding factors affecting survival patterns is therefore critical for developing and testing theories of population dynamics and for developing management strategies aimed at preventing declines or extinction in such taxa. Few studies have used modern analytical approaches for analyzing variation and testing hypotheses about survival probabilities in large mammals. This paper reports a detailed analysis of annual adult survival in the Florida manatee (Trichechus manatus latirostris), an endangered marine mammal, based on a mark-recapture approach. Natural and boat-inflicted scars distinctively 'marked' individual manatees that were cataloged in a computer-based photographic system. Photo-documented resightings provided 'recaptures.' Using open population models, annual adult-survival probabilities were estimated for manatees observed in winter in three areas of Florida: Blue Spring, Crystal River, and the Atlantic coast. After using goodness-of-fit tests in Program RELEASE to search for violations of the assumptions of mark-recapture analysis, survival and sighting probabilities were modeled under several different biological hypotheses with Program SURGE. Estimates of mean annual probability of sighting varied from 0.948 for Blue Spring to 0.737 for Crystal River and 0.507 for the Atlantic coast. At Crystal River and Blue Spring, annual survival probabilities were best estimated as constant over the study period at 0.96 (95% CI = 0.951-0.975 and 0.900-0.985, respectively). On the Atlantic coast, where manatees are impacted more by human activities, annual survival probabilities had a significantly lower mean estimate of 0.91 (95% CI = 0.887-0.926) and varied unpredictably over the study period. For each study area, survival did not differ between sexes and was independent of relative adult age. The high constant adult-survival probabilities estimated for manatees in the Blue Spring and Crystal River areas were consistent with current mammalian life history theory and other empirical data available for large, long-lived mammals. Adult survival probabilities in these areas appeared high enough to maintain growing populations if other traits such as reproductive rates and juvenile survival were also sufficiently high lower and variable survival rates on the Atlantic coast are cause for concern.

Ecology↗

USGS1999

Sand lance: A review of biology and predator relations and annotated bibliography

Six species of sand lance ( Ammodytes ) in temperate and boreal regions are currently recognized. Sand lance can occupy a wide range of environmental conditions, but all appear to be dormant predominantly in winter, and one species is in summer also. They lack a swim bladder and spend much of their time buried in specific substrates. Copepods are the primary food. Spawning usually occurs in fall or winter (although some species also spawn in spring), eggs are demersal, and larvae may hatch at times of low food abundance. Sand lance usually occur in schools and are regarded as a relatively high-quality forage fish. Sand lance constitute a major prey for at least some populations of over 100 species of consumer, including 40 species of birds, 12 species of marine mammals, 45 species of fishes, and some invertebrates. Variation in the availability of sand lance (and other forage fishes) can have major effects on the breeding success and survival of their predators. Commercial fishing and other pressures on sand lance populations potentially have ramifying effects on many species of wildlife. The bibliography contains over 1,700 references on the family Ammodytidae, with an emphasis on the genus Ammodytes . Keywords are provided for each reference and have been further organized into taxonomic, geographic, subject, and predator indexes.

Research Paper↗

USGS2016

California State Waters map series — Offshore of Aptos, California

Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar bathymetric data (the undersea equivalent of satellite remote-sensing data in terrestrial mapping), acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology. The Offshore of Aptos map area is located on the Pacific Coast, on the north side of Monterey Bay, about 105 km southeast of San Francisco. The largest incorporated city in the map area, Capitola, and numerous unincorporated towns including Aptos, lie on uplifted marine terraces between the shoreline, and the northwest-trending Santa Cruz Mountains, part of California’s Coast Ranges. The map area includes the northernmost part of Santa Cruz Harbor, and Moss Landing Harbor is located about 10 km south of the map area. The offshore part of the map area is entirely within California’s State Waters and is also part of the Monterey Bay National Marine Sanctuary. In the southern part of the map area, the Soquel Canyon State Marine Conservation Area extends eastward from the limit of California’s State Waters across Soquel Canyon. The Offshore of Aptos map area is on the western margin of North American Plate—the only continental margin in the world delineated largely by transform faults. The San Andreas Fault Zone cuts through the Santa Cruz Mountains just 3.5 km northeast of the map area. The San Gregorio Fault Zone, another major plate-boundary structure, cuts through Monterey Canyon about 13 km southwest of the map area. Ongoing deformation associated with and between these major fault zones has uplifted the Santa Cruz Mountains and formed well-developed sets of marine terraces that characterize almost the entire coastal zone of the map area. The offshore part of the map area consists of relatively flat and shallow continental shelf which is underlain by variable amounts (0 to 30 m) of upper Quaternary shelf, estuarine, and fluvial sediments deposited as sea level fluctuated in the late Pleistocene. Along the southern edge of the map area, the shelf is incised by the head of Soquel Canyon, a northeast-trending tributary to the west-trending Monterey Canyon. During the last sea-level lowstand (the Last Glacial Maximum [LGM], about 21,000 years ago) Soquel Creek flowed through a paleochannel across the emergent shelf into the head of Soquel Canyon. This canyon was disconnected from its onshore watershed during the post-LGM sea-level rise of about 125 m; the abandoned paleochannel was subsequently filled with marine sediment. Coastal sediment in the Offshore of Aptos map area is supplied by coastal watersheds and bluff erosion. Sediment transport in this part of the Santa Cruz littoral cell is primarily from the northwest to the southeast and terminates in the submarine Monterey Canyon. Longshore drift is impeded by jetties at Santa Cruz Harbor, resulting in high beach erosion rates east of the harbor. Sediment dredged from the harbor mouth (estimated 300,000 yds 3 /yr) is currently being used to nourish beaches directly to the east. Farther downcoast, the rapidly eroding beach at Capitola was stabilized by construction of an about 75-m-long groin. This part of central California is exposed to large North Pacific swells from the northwest throughout the year. North Pacific swell heights range from 2 to 10 meters, with larger swells occurring from October to May. During El Niño-Southern Oscillation (ENSO) events, winter storms track farther south than they do in normal (non-ENSO) years, thereby impacting the map area more frequently and with waves of larger heights. Bedrock exposed in coastal cliffs is relatively erosion-resistant, and significant erosional events primarily are restricted to storm-wave activity that also erodes the overlying unconsolidated marine-terrace sediments. The Offshore of Aptos map area lies within the cold-temperate biogeographic zone that is called either the “Oregonian” province or the “northern California ecoregion.” This biogeographic province is maintained by the long-term stability of the southward-flowing California Current, the eastern limb of the North Pacific subtropical gyre that flows from southern British Columbia to Baja California. At its midpoint off central California, the California Current transports subarctic surface (0–500 m deep) waters southward, about 150 to 1,300 km from shore. Seasonal northwesterly winds that are, in part, responsible for the California Current, generate coastal upwelling. The south end of the Oregonian province is at Point Conception (about 310 km southeast of the map area), although its associated phylogeographic group of marine fauna may extend beyond to the area offshore of Los Angeles in southern California. The ocean off of central California has experienced a warming over the last 50 years that is driving an ecosystem shift away from the productive subarctic regime towards a depopulated subtropical environment. Seafloor habitats in the Offshore of Aptos map area lie within the “Shelf” Megahabitat class and include patchy rocky habitats, gravel-rich scour depressions, minor bedrock habitat, and predominantly sandy inner shelf. Sandy shelf habitats grade offshore to mud-dominated habitats on the midshelf in deeper water. Biological productivity resulting from coastal upwelling supports populations of Sooty Shearwater, Western Gull, Common Murre, Cassin’s Auklet, and many other less populous bird species. In addition, an observable recovery of Humpback and Blue Whales has occurred in the area; both species are dependent on coastal upwelling to provide nutrients. California sea lions and Pacific harbor seals are abundant in the map area. Common bottlenose dolphins are often observed very close to shore and in the surf zone. The large extent of exposed inner shelf bedrock supports large forests of “bull kelp,” which is well adapted for high-wave-energy environments. The kelp beds are the northernmost known habitat for the population of southern sea otters. Common fish species found in the kelp beds and rocky reefs include blue rockfish, black rockfish, olive rockfish, kelp rockfish, gopher rockfish, black-and-yellow rockfish, painted greenling, kelp greenling, and lingcod.

California↗

USGS2006

Taxonomic considerations in listing subspecies under the U.S. Endangered Species Act

The U.S. Endangered Species Act (ESA) allows listing of subspecies and other groupings below the rank of species. This provides the U.S. Fish and Wildlife Service and the National Marine Fisheries Service with a means to target the most critical unit in need of conservation. Although roughly one-quarter of listed taxa are subspecies, these management agencies are hindered by uncertainties about taxonomic standards during listing or delisting activities. In a review of taxonomic publications and societies, we found few subspecies lists and none that stated standardized criteria for determining subspecific taxa. Lack of criteria is attributed to a centuries-old debate over species and subspecies concepts. Nevertheless, the critical need to resolve this debate for ESA listings led us to propose that minimal biological criteria to define disjunct subspecies (legally or taxonomically) should include the discreteness and significance criteria of distinct population segments (as defined under the ESA). Our subspecies criteria are in stark contrast to that proposed by supporters of the phylogenetic species concept and provide a clear distinction between species and subspecies. Efforts to eliminate or reduce ambiguity associated with subspecies-level classifications will assist with ESA listing decisions. Thus, we urge professional taxonomic societies to publish and periodically update peer-reviewed species and subspecies lists. This effort must be paralleled throughout the world for efficient taxonomic conservation to take place.

Conservation Biology↗

USGS1979

Biogenic and thermogenic gas in gas-charged sediment of Norton Sound, Alaska

Chemical and isotopic compositions of sediment gas from Norton Sound have been determined for near-surface, gas-charged sediments at two sites identified in acoustic profiles and bottom observations. At one site air-driven vibracorer penetrated sediment saturated with methane. The isotopic value suggests that the methane originated from active biological processes operating on peat in the top 4 m of sediment. At the other site, characterized by a large subsurface acoustic anomaly , smaller near-surface acoustic anomalies and active seepage of gas, the vibracorer obtained sediment saturated with gas composed of 98% CO2. Associated with the CO2 are minor concentrations of petroleum-like light hydrocarbons. The carbon isotopic compositions of CO2 and methane along with the chemical distribution of gaseous hydrocarbons indicate that at this site these gases are derived from thermal processes operating at depth in Norton Basin. Apparently CO2 from the decarbonation of marine limestone acts as a carrier for hydrocarbon gases that have been generated from organic matter buried in the basin. The gases reach the surface by faults and escape at the seafloor as a submarine seep. The presence of near-surface gas-charged sediment in Norton Sound reduces the stability of the seafloor. Areas where sediments are charged with gas may pose potential hazards for engineering developments.

Alaska↗

USGS2015

Pollen and spores of terrestrial plants

Pollen and spores are valuable tools in reconstructing past sea level and climate because of their ubiquity, abundance, and durability as well as their reciprocity with source vegetation to environmental change (Cronin, 1999; Traverse, 2007; Willard and Bernhardt, 2011). Pollan is found in many sedimentary environments, from freshwater to saltwater, terrestrial to marine. It can be abundant in a minimal amount of sample material, for example half a gram, as concentrations can be as high as four million grains per gram (Traverse, 2007). The abundance of pollen in a sample lends it to robust statistical analysis for the quantitative reconstruction of environments. The outer cell wall is resistant to decay in sediments and allows palynomorphs (pollen and spores) to record changes in plant communities and sea level over millions of years. These characteristics make pollen and spores a powerful tool to use in sea-level research. This chapter describes the biology of pollen and spores and how they are transported and preserved in sediments. We present a methodology for isolating pollen from sediments and a general language and framework to identify pollen as well as light micrographs of a selection of common pollen grains, We then discuss their utility in sea-level research.

Book chapter↗

USGS2019

Estimating connectivity of hard clam (Mercenaria mercenaria) and eastern oyster (Crassostrea virginica) larvae in Barnegat Bay

Many marine organisms have a well-known adult sessile stage. Unfortunately, our lack of knowledge regarding their larval transient stage hinders our understanding of their basic ecology and connectivity. Larvae can have swimming behavior that influences their transport within the marine environment. Understanding the larval stage provides insight into population connectivity that can help strategically identify areas for restoration. Current techniques for understanding the larval stage include modeling that combines particle attributes (e.g., larval behavior) with physical processes of water movement to contribute to our understanding of connectivity trends. This study builds on those methods by using a previously developed retention clock matrix (RCM) to illustrate time dependent connectivity of two species of shellfish between areas and over a range of larval durations. The RCM was previously used on physical parameters but we expand the concept by applying it to biology. A new metric, difference RCM (DRCM), is introduced to quantify changes in connectivity under different scenarios. Broad spatial trends were similar for all behavior types with a general south to north progression of particles. The DRCMs illustrate differences between neutral particles and those with behavior in northern regions where stratification was higher, indicating that larval behavior influenced transport. Based on these findings, particle behavior led to small differences (north to south movement) in transport patterns in areas with higher salinity gradients (the northern part of the system) compared to neutral particles. Overall, the dominant direction for particle movement was from south to north, which at times was enhanced by winds from the south. Clam and oyster restoration in the southern portion of Barnegat Bay could serve as a larval supply for populations in the north. These model results show that coupled hydrodynamic and particle tracking models have implications for fisheries management and restoration activities.

New Jersey↗

USGS1994

Indicators of sewage contamination in sediments beneath a deep-ocean dump site off New York

The world's largest discharge of municipal sewage sludge to surface waters of the deep sea has caused measurable changes in the concentration of sludge indicators in sea-floor sediments, in a spatial pattern which agrees with the predictions of a recent sludge deposition model. Silver, linear alkylbenzenes, coprostanol, and spores of the bacterium Clostridium perfringens, in bottom sediments and in near-bottom suspended sediment, provide evidence for rapid settling of a portion of discharged solids, accumulation on the sea floor, and biological mixing beneath the water sediment interface. Biological effects include an increase in 1989 of two species of benthic polychaete worm not abundant at the dump site before sludge dumping began in 1986. These changes in benthic ecology are attributed to the increased deposition of utilizable food in the form of sludge-derived organic matter.

New Jersey, New York↗

USGS2004

Chapter 11 The phosphoria formation: A model for forecasting global selenium sources to the environment

Mining of the Permian Phosphoria Formation — a marine, oil-generating, phosphatic shale — provided the selenium (Se) source implicated in the recent deaths of livestock in southeast Idaho. Field studies and the geohydrologic balance of Se in southeast Idaho confirm risk to animals from exposure to Se through leaching of mined waste shale into streams, discharge of regional drainage, and impoundment of drainage in wetland areas. Forage grown to stabilize waste rock contoured into hills or used as cross-valley fill provides an additional mechanism of Se exposure for the environment (Mackowiak et al., Chapter 19). The average Se concentration of the Meade Peak Member of the Phosphoria Formation is an order of magnitude higher than those of other exploited marine shales that have been linked to incidences of Se toxicosis via oil refining and irrigation in the western United States. The Phosphoria Formation accumulated in an environment that preserved organic matter and contributed to the formation of economic-grade phosphate and oil deposits. The addition of this phosphate-mining case study enables a comprehensive approach to the identification of marine sedimentary Se sources and a more complete range of ecotoxic field studies on which to establish the conditions and anthropogenic connections that determine uptake, release, and recycling of Se in food webs. A constructed conceptual model of Se pollution indicates that ancient organic-rich depositional marine basins, unre- stricted by age, are linked to the contemporary global distribution of Se source rocks. A global plot shows (a) the areal association of major basins hosting phosphate deposits and petroleum source rocks and (b) the importance of paleo-latitudinal setting in influencing the composition of the deposits. Given the geographic patterns, Se emerges as a contami- nant within specific regions of the globe that may limit phosphate mining, oil refining, and drainage of agricultural lands because of potential ecological risks to vulnerable food webs. Selenium also may serve as a geochemical exploration tool that signals an ancient productive biological environment.

Handbook of Exploration and Environmental Geochemi↗