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At least 559 records · Page 31Linked to original sources

USGS2010

Fix success and accuracy of GPS radio collars in old-growth temperate coniferous forests

Global Positioning System (GPS) telemetry is used extensively to study animal distribution and resource selection patterns but is susceptible to biases resulting from data omission and spatial inaccuracies. These data errors may cause misinterpretation of wildlife habitat selection or spatial use patterns. We used both stationary test collars and collared free-ranging American black bears ( Ursus americanus ) to quantify systemic data loss and location error of GPS telemetry in mountainous, old-growth temperate forests of Olympic National Park, Washington, USA. We developed predictive models of environmental factors that influence the probability of obtaining GPS locations and evaluated the ability of weighting factors derived from these models to mitigate data omission biases from collared bears. We also examined the effects of microhabitat on collar fix success rate and examined collar accuracy as related to elevation changes between successive fixes. The probability of collars successfully obtaining location fixes was positively associated with elevation and unobstructed satellite view and was negatively affected by the interaction of overstory canopy and satellite view. Test collars were 33% more successful at acquiring fixes than those on bears. Fix success rates of collared bears varied seasonally and diurnally. Application of weighting factors to individual collared bear fixes recouped only 6% of lost data and failed to reduce seasonal or diurnal variation in fix success, suggesting that variables not included in our model contributed to data loss. Test collars placed to mimic bear bedding sites received 16% fewer fixes than randomly placed collars, indicating that microhabitat selection may contribute to data loss for wildlife equipped with GPS collars. Horizontal collar errors of >800 m occurred when elevation changes between successive fixes were >400 m. We conclude that significant limitations remain in accounting for data loss and error inherent in using GPS telemetry in coniferous forest ecosystems and that, at present, resource selection patterns of large mammals derived from GPS telemetry should be interpreted cautiously.

Washington↗

USGS2018

Hawai‘i and U.S.-Affiliated Pacific Islands

The U.S. Pacific Islands are culturally and environmentally diverse, treasured by the 1.9 million people who call them home. Pacific islands are particularly vulnerable to climate change impacts due to their exposure and isolation, small size, low elevation (in the case of atolls), and concentration of infrastructure and economy along the coasts. A prevalent cause of year-to-year changes in climate patterns around the globe and in the Pacific Islands region is the El Niño –Southern Oscillation (ENSO). The El Niño and La Niña phases of ENSO can dramatically affect precipitation, air and ocean temperature, sea surface height, storminess, wave size, and trade winds. It is unknown exactly how the timing and intensity of ENSO will continue to change in the coming decades, but recent climate model results suggest a doubling in frequency of both El Niño and La Niña extremes in this century as compared to the 20th century under scenarios with more warming, including the higher scenario (RCP8.5). On islands, all natural sources of freshwater come from rainfall received within their limited land areas. Severe droughts are common, making water shortage one of the most important climate-related risks in the region. As temperature continues to rise and cloud cover decreases in some areas, evaporation is expected to increase, causing both reduced water supply and higher water demand. Streamflow in Hawai‘i has declined over approximately the past 100 years, consistent with observed decreases in rainfall. The impacts of sea level rise in the Pacific include coastal erosion, episodic flooding, permanent inundation, heightened exposure to marine hazards, and saltwater intrusion to surface water and groundwater systems. Sea level rise will disproportionately affect the tropical Pacific and potentially exceed the global average. Invasive species , landscape change, habitat alteration, and reduced resilience have resulted in extinctions and diminished ecosystem function. Inundation of atolls in the coming decades is projected to impact existing on-island ecosystems. Wildlife that relies on coastal habitats will likely also be severely impacted. In Hawaiʻi, coral reefs contribute an estimated $477 million to the local economy every year. Under projected warming of approximately 0.5°F per decade, all nearshore coral reefs in the Hawai‘i and Pacific Islands region will experience annual bleaching before 2050. An ecosystem -based approach to international management of open ocean fisheries in the Pacific that incorporates climate-informed catch limits is expected to produce more realistic future harvest levels and enhance ecosystem resilience. Indigenous communities of the Pacific derive their sense of identity from the islands. Emerging issues for Indigenous communities of the Pacific include the resilience of marine-managed areas and climate-induced human migration from their traditional lands. The rich body of traditional knowledge is place-based and localized and is useful in adaptation planning because it builds on intergenerational sharing of observations. Documenting the kinds of governance structures or decision-making hierarchies created for management of these lands and waters is also important as a learning tool that can be shared with other island communities. Across the region, groups are coming together to minimize damage and disruption from coastal flooding and inundation as well as other climate-related impacts. Social cohesion is already strong in many communities, making it possible to work together to take action. Early intervention can lower economic, environmental, social, and cultural costs and reduce or prevent conflict and displacement from ancestral land and resources.

Report↗

USGS2025

Understanding and managing introduction pathways into protected areas in a changing climate

The Kunming-Montreal Global Biodiversity Framework 2030 calls for the conservation of 30% of the world’s ecosystems, focusing on protecting areas vital to biodiversity, identifying and managing invasive species introduction pathways, and minimizing the impacts of climate change on biodiversity. While protected areas (PAs) have historically limited the introduction, establishment, and spread of non-native species, climate change is likely to increase their susceptibility to invasion. Yet we know little about how pathways may shift in the future, making it difficult for managers to plan appropriately. This paper explores how climate change may affect primary and secondary pathways of introduction and presents an adaptive management approach to avoid, minimize, and mitigate impacts. Climate change has influenced introduction pathways by modifying human behaviors (e.g., forced migration and shifting travel and vacation destinations), and by altering transportation routes, natural dispersal mechanisms, and the environmental conditions along these pathways and in donor and receiver regions. These changes increase the risk of non-native species introductions and their subsequent spread within PAs. Implementing climate-smart adaptive biosecurity, an iterative process that includes the incorporation of new technologies and perspectives, will become increasingly important for invasive species prevention and management of PAs as it provides flexibility in management response and maximizes positive outcomes when resources are limited.

Biological Invasions↗

USGS2019

Migration routes, foraging behavior, and site fidelity of loggerhead sea turtles (Caretta caretta) satellite tracked from a globally important rookery

The Archie Carr National Wildlife Refuge, Florida, USA (27.946°N, − 80.494°W) represents one of the largest loggerhead turtle ( Caretta caretta ) nesting sites in the Western Hemisphere. Surprisingly, little work has been conducted to determine females’ post-nesting migratory behavior and characteristics of their foraging areas. Between 2008 and 2017, satellite telemetry was used to trace the locations and movements of 45 post-nesting loggerhead turtles. A switching state-space model was employed to estimate the behavioral state of each location. Internesting, migrating and foraging activity periods were determined for 38 loggerheads based on the SSSM. Seven environmental variables were extracted from remote sensing imagery for each location to compare values among behaviors. Core primary foraging areas ranged in size from 5.89 to 4572.80 km 2 . Four foraging types (primary, secondary, seasonal, and loops) were observed. Most turtles resided at a primary foraging area year round. A few individuals conducted foraging loops away from a primary foraging area. Both seasonal and loop movements were associated with changes in sea surface temperature as turtles moved to avoid temperatures that could cause cold-stunning or mortality. Turtle size and nesting beach offshore currents may play a role in foraging area selection, and date of departure from the nesting beach may be linked to foraging destination. By making the connection among oceanic features, foraging areas, and the influence of environmental variables on these areas, it is possible to identify and characterize critically important feeding areas and migration corridors for loggerheads nesting on the east coast of Florida.

Marine Biology↗

USGS2017

Genomics of Arctic cod

The Arctic cod (Boreogadus saida) is an abundant marine fish that plays a vital role in the marine food web. To better understand the population genetic structure and the role of natural selection acting on the maternally-inherited mitochondrial genome (mitogenome), a molecule often associated with adaptations to temperature, we analyzed genetic data collected from 11 biparentally-inherited nuclear microsatellite DNA loci and nucleotide sequence data from from the mitochondrial DNA (mtDNA) cytochrome b (cytb) gene and, for a subset of individuals, the entire mitogenome. In addition, due to potential of species misidentification with morphologically similar Polar cod (Arctogadus glacialis), we used ddRAD-Seq data to determine the level of divergence between species and identify species-specific markers. Based on the findings presented here, Arctic cod across the Pacific Arctic (Bering, Chukchi, and Beaufort Seas) comprise a single panmictic population with high genetic diversity compared to other gadids. High genetic diversity was indicated across all 13 protein-coding genes in the mitogenome. In addition, we found moderate levels of genetic diversity in the nuclear microsatellite loci, with highest diversity found in the Chukchi Sea. Our analyses of markers from both marker classes (nuclear microsatellite fragment data and mtDNA cytb sequence data) failed to uncover a signal of microgeographic genetic structure within Arctic cod across the three regions, within the Alaskan Beaufort Sea, or between near-shore or offshore habitats. Further, data from a subset of mitogenomes revealed no genetic differentiation between Bering, Chukchi, and Beaufort seas populations for Arctic cod, Saffron cod (Eleginus gracilis), or Walleye pollock (Gadus chalcogrammus). However, we uncovered significant differences in the distribution of microsatellite alleles between the southern Chukchi and central and eastern Beaufort Sea samples of Arctic cod. Finally, using ddRAD-Seq data, we identified species-specific markers and in conjunction with mitogenome data, identified an Arctic cod x Polar cod hybrid in western Canadian Beaufort Sea. Overall, the lack of genetic structure among Arctic cod within the Bering, Chukchi and Beaufort seas of Alaska is concordant with the absence of geographic barriers to dispersal and typical among marine fishes. Arctic cod may exhibit a genetic pattern of isolation-by-distance, whereby populations in closer geographic proximity are more genetically similar than more distant populations. As this signal is only found between our two fartherest localities, data from populations elsewhere in the species’ global range are needed to determine if this is a general characteristic. Further, tests for selection suggested a limited role for natural selection acting on the mitochondrial genome of Arctic cod, but do not exclude the possibility of selection on genes involved in nuclear-mitogenome interactions. Unlike previous genetic assessment of Arctic cod sampled from the Chukchi Sea, the high levels of genetic diversity found in Arctic cod assayed in this study, across regions, suggests that the species in the Beaufort and Chukchi seas does not suffer from low levels of genetic variation, at least at neutral genetic markers. The large census size of Arctic cod may allow this species to retain high levels of genetic diversity. In addition, we discovered the presence of hybridization between Arctic and Polar cod (although low in frequency). Hybridization is expected to occur when environmental changes modify species distributions that result in contact between species that were previously separated. In such cases, hybridization may be an evolutionary mechanism that promotes an increase in genetic diversity that may provide species occupying changing environments with locally-adapted genotypes and, therefore, phenotypes. Natural selection can only act on the standing genetic variation present within a population. Therefore, given its higher levels of genetic diversity in combination with a large population size, Arctic cod may be resilient to current and future environmental change, as high genetic diversity is expected to increase opportunities for positive selection to act on genetic variants beneficial in different environments, regardless of the source of that genetic variation.

OCS Study↗

USGS2013

Dynamics of land-use change and conservation in the Prairie Pothole Region of the United States: environmental and economic implications with linkages to rural community well-being

Rural America has changed dramatically over the last century, from having over half the population living in rural settings to only 20 percent residing in a rural area today, and outmigration of younger populations from rural communities remains a constant issue for local governing officials. A declining tax base and concurrent rising costs for maintenance and repair of aging infrastructure add further challenges to policy decisions. Reduced enrollment has caused school closures or mergers. Farm consolidation and technical advances reduced the demand for local labor. On the positive side, however, record-high commodity prices have amplified farm income to new heights. The increased revenues can lead to farmers spending additional money within the local region, while at the same time increased transportation of products has impacted local infrastructure such as roads and bridges. Such dynamics present challenges for municipal leaders charged with promoting economic development and balanced spending, while at the same time maintaining the way of life and rural character that are so important to area residents. The Prairie Pothole Region (PPR) of the United States covers much of the Northern Great Plains, including parts of North and South Dakota, Minnesota, Iowa, and a small part of Montana, and extends across a broad swath of Alberta and Saskatchewan. The region is defined largely by its rural character but has experienced extensive land conversion over the last century, with agricultural areas replacing native prairie habitat. Additional pressures arise from oil and gas development, global markets for agricultural production, and increased demands for biofuel feedstocks. Record-high commodity prices increase pressure on the native prairie as farmers look for new cropland acres. The volatility of commodity prices has raised fears over the intensity of land conversion to row-crop agriculture, the economic health and resiliency of rural communities, and ultimately, population dynamics and outmigration of younger generations. Land-use pressures are increased by the exponential growth of oil and gas production in the region, where some 8,200 wells are now in production within the Williston Basin of North Dakota, accompanied by increased population pressures on housing and municipal services. The U.S. Department of Agriculture’s Conservation Reserve Program (CRP)--a cropland retirement program with close to 4.8 million acres enrolled in the PPR--faces uncertainty in upcoming legislative actions, with a large majority of property enrollments scheduled to expire by 2017. The CRP historically has provided improved habitat conditions, reductions of soil damage through erosion and loss of nutrients, and sequestration of millions of tons of atmospheric carbon. In turn, wildlife-related recreation levels have increased in many parts of the PPR, with money spent in local communities. Contemporary resource-management and rural-development planning increasingly emphasize the need for diversification and integration of resource-extractive industries with nonmarket-based recreational and amenity values that tie into quality of life. Ultimately, each community is unique in its environmental, social, economic, and fiscal endowments. One rural-development policy may work better in one community than another. In addition, rural-development issues such as migration, job growth, and taxes are diverse in themselves. The goal of this report is to qualitatively and quantitatively discuss the economic impacts of land-use decisions in rural areas, particularly in the PPR.

Professional Paper↗

USGS2023

Multi-level thresholds of residential and agricultural land use for elk avoidance across the Greater Yellowstone Ecosystem

1. Conversion of land for settlements and agriculture is increasing globally and can influence wildlife space use. However, there is limited research to identify the thresholds of land-use change that incur wildlife avoidance and how these thresh-olds might vary across levels of selection. 2. We evaluated multi-level avoidance thresholds of elk Cervus canadensis impacted by residential development and irrigated agriculture across the Greater Yellowstone Ecosystem in Idaho, Montana and Wyoming. Using GPS data from765 elk in 21 herds, we estimated habitat selection in relation to development and agriculture at three levels (home range selection, within home range selection and movement path selection). Next, using individual selection covariates and as-sociated measures of land-use availability, we used functional-response models to evaluate how selection varied based on availability, and in turn, to estimate avoidance thresholds. 3. We found individual and level-specific variation in elk responses to environmental factors. Elk exhibited stronger responses (either selection or avoidance) when selecting home range locations (i.e. second-order selection) than when selecting areas within home ranges (i.e. third-order selection) or selecting movement paths (i.e. fourth-order selection). Importantly, elk avoidance of development and agriculture changed as the amount of land in these categories changed. Across all levels of selection elk exhibited neutral selection for human development at low levels of availability (<1.1%–2.2% developed) but avoided areas that were >1.1%–2.2% developed. Conversely, elk selected positively for irrigated agriculture at low to moderate levels of availability (<52.0%–66.2% agriculture) but exhibited neutral selection in areas that were >52.0%–66.2% agriculture. 4. Synthesis and applications . Elk avoidance of low levels of human development suggests conservation efforts such as restrictions on future development or conservation easements could focus on areas that are still below 2% developed. Additionally, because elk selection was strongest at the landscape scale, conservation actions that are based on information about the overall landscape structure may be most impactful. Our results highlight the importance of under-standing variability in wildlife habitat selection at multiple levels, particularly in relation to land-use change, and highlight how functional response modelling can help inform landscape conservation.

Montana, Wyoming↗

USGS2016

Effects of Lead Exposure, Environmental Conditions, and Metapopulation Processes on Population Dynamics of Spectacled Eiders.

Spectacled eider Somateria fischeri numbers have declined and they are considered threatened in accordance with the US Endangered Species Act throughout their range. We synthesized the available information for spectacled eiders to construct deterministic, stochastic, and metapopulation models for this species that incorporated current estimates of vital rates such as nest success, adult survival, and the impact of lead poisoning on survival. Elasticities of our deterministic models suggested that the populations would respond most dramatically to changes in adult female survival and that the reductions in adult female survival related to lead poisoning were locally important. We also examined the sensitivity of the population to changes in lead exposure rates. With the knowledge that some vital rates vary with environmental conditions, we cast stochastic models that mimicked observed variation in productivity. We also used the stochastic model to examine the probability that a specific population will persist for periods of up to 50 y. Elasticity analysis of these models was consistent with that for the deterministic models, with perturbations to adult female survival having the greatest effect on population projections. When used in single population models, demographic data for some localities predicted rapid declines that were inconsistent with our observations in the field. Thus, we constructed a metapopulation model and examined the predictions for local subpopulations and the metapopulation over a wide range of dispersal rates. Using the metapopulation model, we were able to simulate the observed stability of local subpopulations as well as that of the metapopulation. Finally, we developed a global metapopulation model that simulates periodic winter habitat limitation, similar to that which might be experienced in years of heavy sea ice in the core wintering area of spectacled eiders in the central Bering Sea. Our metapopulation analyses suggested that no subpopulation is independent and that future management actions may be improved through a metapopulation framework. For example, management actions could include displacement of breeding females from"sink" areas that reduce the growth potential of the population as a whole. However, this action is contingent upon dispersal among local populations, for which there is limited information. Thus, we recommend that researchers examine dispersal behavior among areas on the Yukon-Kuskokwim Delta in western Alaska. The metapopulation framework could also be applied at the rangewide scale to address the density-dependent limitation of available polynya habitat during winter that may limit the recovery of small subpopulations, such as that on the Yukon-Kuskokwim Delta. Reductions in other subpopulations may be necessary to ensure an increase in the Yukon-Kuskokwim Delta population. Thus, we recommend that managers consider the interpopulation dynamics of spectacled eiders at different spatial scales in future management actions.

Alaska↗

USGS2018

Millennial soil retention of terrestrial organic matter deposited in the Bengal Fan

The abundance of organic carbon (OC) in vegetation and soils (~2,600 PgC) compared to carbon in the atmosphere (~830 PgC) highlights the importance of terrestrial OC in global carbon budgets. The residence time of OC in continental reservoirs, which sets the rates of carbon exchange between land and atmosphere, represents a key uncertainty in global carbon cycle dynamics. Retention of terrestrial OC can also distort bulk OC- and biomarker-based paleorecords, yet continental storage timescales remain poorly quantified. Using “bomb” radiocarbon (14C) from thermonuclear weapons testing as a tracer, we model leaf-wax fatty acid and bulk OC 14C signatures in a river-proximal marine sediment core from the Bay of Bengal in order to constrain OC storage timescales within the Ganges-Brahmaputra (G-B) watershed. Our model shows that 79-83% of the leaf-waxes in this core were stored in continental reservoirs for an average of 1,000-1,200 calendar years, while the remainder was stored for an average of 15 years. This age structure distorts high-resolution organic paleorecords across geologically rapid events, highlighting that compound-specific proxy approaches must consider storage timescales. Furthermore, these results show that future environmental change could destabilize large stores of old - yet reactive - OC currently stored in tropical basins.

Scientific Reports↗

USGS2020

Building adaptive capacity in a coastal region experiencing global change

Coastal ecosystems in the eastern U.S. have been severely altered by human development, and climate change and other stressors are now further degrading the capacity of those ecological and social systems to remain resilient in the face of such disturbances. We sought to identify potential ways in which local conservation interests in the Lowcountry of South Carolina (USA) could participate in a social process of adaptation planning, and how that process might ultimately be broadened to engage a more diverse set of partners. We engaged participants through a combination of informal meetings, workshops, and other collaborative interactions to explore how the conservation community perceives and pursues its various missions, and how that community might confront the threats and opportunities in its future. Coproduction of knowledge and meaning were facilitated by collaborative scenario planning and strategic planning evaluation, which illuminated how the conservation community is integral to the broader governance of the region and highlighted how responses to forces of change are mediated through local culture, economics, and politics. We suggest an interpretation of conservation in which the fundamental objectives of both social and ecological systems might be prioritized in tandem, rather than narrowly focusing on environmental protection without consideration of the social landscape. Ultimately, adaptive capacity depends on the ability to act collectively, and social capital, trust, and organization greatly influence the capacity to act. Thus, we conclude that the presence of strong social networks, coordination and deliberation among diverse stakeholders, mechanisms for experiential feedback, and emphasis on social learning are key elements needed to build adaptive capacity. Central to the evolving perspective of governance of the commons is recognition that social and ecological systems are coupled; the issues and problems of one cannot be addressed without considering the consequences for the other. Moreover, a dominant theme emerging from our research and that of other scholars is the importance of culture and place attachment, which generates social cohesion and facilitates problem solving. These ideas have important implications for when, where, and how stakeholders are engaged to address the rapid changes being experienced by social-ecological systems.

South Carolina↗

USGS2017

Evidence for millennial-scale climate change during marine isotope stages 2 and 3 at Little Lake, Western Oregon, U.S.A.

Pollen and geochemical data from Little Lake, western Oregon, suggest several patterns of millennial-scale environmental change during marine isotope stage (MIS) 2 (14,100-27,600 cal yr B.P.) and the latter part of MIS 3 (27,600-42,500 cal yr B.P.). During MIS 3, a series of transitions between warm- and cold-adapted taxa indicate that temperatures oscillated by ca. 2??-4??C every 1000-3000 yr. Highs and lows in summer insolation during MIS 3 are generally associated with the warmest and coldest intervals. Warm periods at Little Lake correlate with warm sea-surface temperatures in the Santa Barbara Basin. Changes in the strength of the subtropical high and the jet stream may account for synchronous changes at the two sites. During MIS 2, shifts between mesic and xeric subalpine forests suggest changes in precipitation every 1000-3000 yr. Increases in Tsuga heterophylla pollen at 25,000 and 22,000 cal yr B.P. imply brief warmings. Minimum summer insolation and maximum global ice-volumes during MIS 2 correspond to cold and dry conditions. Fluctuations in precipitation at Little Lake do not correlate with changes in the Santa Barbara Basin and may be explained by variations in the strength of the glacial anticyclone and the position of the jet stream. ?? 2001 University of Washington.

Quaternary Research↗

USGS1996

Potential role of vegetation feedback in the climate sensitivity of high-latitude regions: A case study at 6000 years B.P.

Previous climate model simulations have shown that the configuration of the Earth's orbit during the early to mid-Holocene (approximately 10–5 kyr) can account for the generally warmer-than-present conditions experienced by the high latitudes of the northern hemisphere. New simulations for 6 kyr with two atmospheric/mixed-layer ocean models (Community Climate Model, version 1, CCMl, and Global ENvironmental and Ecological Simulation of Interactive Systems, version 2, GENESIS 2) are presented here and compared with results from two previous simulations with GENESIS 1 that were obtained with and without the albedo feedback due to climate-induced poleward expansion of the boreal forest. The climate model results are summarized in the form of potential vegetation maps obtained with the global BIOME model, which facilitates visual comparisons both among models and with pollen and plant macrofossil data recording shifts of the forest-tundra boundary. A preliminary synthesis shows that the forest limit was shifted 100–200 km north in most sectors. Both CCMl and GENESIS 2 produced a shift of this magnitude. GENESIS 1 however produced too small a shift, except when the boreal forest albedo feedback was included. The feedback in this case was estimated to have amplified forest expansion by approximately 50%. The forest limit changes also show meridional patterns (greatest expansion in central Siberia and little or none in Alaska and Labrador) which have yet to be reproduced by models. Further progress in understanding of the processes involved in the response of climate and vegetation to orbital forcing will require both the deployment of coupled atmosphere-biosphere-ocean models and the development of more comprehensive observational data sets.

Global Biogeochemical Cycles↗

USGS2017

Sea turtles, light pollution, and citizen science: A preliminary report

Sea turtles are an important ecological resource for Gulf Islands National Seashore’s (Gulf Islands) waters and shorelines. Regionally, sea turtles face anthropogenic threats from situations such as entanglement in fishing gear and ingestion of marine debris, as well as possible changes in sex ratios due to increasing temperatures related to human-induced global warming. Locally, light pollution from residential, commercial, and industrial neighborhoods from nearby cities impacts the entirety of Gulf Islands, which spans 160 miles along the Gulf Coast, from Florida to Mississippi, and includes critical habitat for threatened and endangered sea turtles. Because light pollution has been hypothesized to negatively impact sea turtle nesting and hatchling survival, Gulf Islands undertook an effort to understand the relationship between light pollution and sea turtles and create unique educational and outreach opportunities by launching a citizen science program called Turtle Teens Helping in the Seashore (Turtle THIS). At the onset, the Turtle THIS program had two primary goals: quantify the association between light pollution and sea turtle nesting and hatching events using rigorous scientific methods; and initiate a citizen science volunteer program to provide youth with hands-on science and environmental stewardship roles, where they also gain employable skills and career opportunities. With multiple scientific hypotheses to consider, the development of a citizen science program became crucial. Such circumstances allowed Turtle THIS to grow a volunteer and intern program, quantify hypothesized light effects on sea turtles through developed methods, and begin to gather preliminary findings.

Florida↗

USGS2013

Geochemical monitoring for potential environmental impacts of geologic sequestration of CO 2

Carbon dioxide sequestration is now considered an important component of the portfolio of options for reducing greenhouse gas emissions to stabilize their atmospheric levels at values that would limit global temperature increases to the target of 2 °C by the end of the century (Pacala and Socolow 2004; IPCC 2005, 2007; Benson and Cook 2005; Benson and Cole 2008; IEA 2012; Romanak et al. 2013). Increased anthropogenic emissions of CO2 have raised its atmospheric concentrations from about 280 ppmv during pre-industrial times to ~400 ppmv today, and based on several defined scenarios, CO2 concentrations are projected to increase to values as high as 1100 ppmv by 2100 (White et al. 2003; IPCC 2005, 2007; EIA 2012; Global CCS Institute 2012). An atmospheric CO2 concentration of 450 ppmv is generally the accepted level that is needed to limit global temperature increases to the target of 2 °C by the end of the century. This temperature limit likely would moderate the adverse effects related to climate change that could include sea-level rise from the melting of alpine glaciers and continental ice sheets and from the ocean warming; increased frequency and intensity of wildfires, floods, droughts, and tropical storms; and changes in the amount, timing, and distribution of rain, snow, and runoff (IPCC 2007; Sundquist et al. 2009; IEA 2012). Rising atmospheric CO2 concentrations are also increasing the amount of CO2 dissolved in ocean water lowering its pH from 8.1 to 8.0, with potentially disruptive effects on coral reefs, plankton and marine ecosystems (Adams and Caldeira 2008; Schrag 2009; Sundquist et al. 2009). Sedimentary basins in general and deep saline aquifers in particular are being investigated as possible repositories for the large volumes of anthropogenic CO2 that must be sequestered to mitigate global warming and related climate changes (Hitchon 1996; Benson and Cole 2008; Verma and Warwick 2011).

Reviews in Mineralogy and Geochemistry↗

USGS2017

High pressure size exclusion chromatography (HPSEC) determination of dissolved organic matter molecular weight revisited: Accounting for changes in stationary phases, analytical standards, and isolation methods

We reassessed the molecular weight of dissolved organic matter (DOM) determined by high pressure size exclusion chromatography (HPSEC) using measurements made with different columns and various generations of polystyrenesulfonate (PSS) molecular weight standards. Molecular weight measurements made with a newer generation HPSEC column and PSS standards from more recent lots are roughly 200 to 400 Da lower than initial measurements made in the early 1990s. These updated numbers match DOM molecular weights measured by colligative methods and fall within a range of values calculated from hydroxyl radical kinetics. These changes suggest improved accuracy of HPSEC molecular weight measurements that we attribute to improved accuracy of PSS standards and changes in the column packing. We also isolated DOM from wetlands in the Prairie Pothole Region (PPR) using XAD-8, a cation exchange resin, and PPL, a styrene-divinylbenzene media, and observed little difference in molecular weight and specific UV absorbance at 280 nm (SUVA 280 ) between the two solid phase extraction resins, suggesting they capture similar DOM moieties. PPR DOM also showed lower SUVA 280 at similar weights compared to DOM isolates from a global range of environments, which we attribute to oxidized sulfur in PPR DOM that would increase molecular weight without affecting SUVA 280 .

Environmental Science & Technology↗

USGS2025

Calcareous nannofossil biostratigraphy and floral response to environmental changes recorded in the Pliocene Yorktown Formation, southeastern Virginia, USA

The Pliocene Yorktown Formation, deposited on the U.S. Mid-Atlantic Coastal Plain, has played an important role in advancing our knowledge of Pliocene paleoclimate. To refine the age and paleoenvironment of the Yorktown Formation, we analyzed the calcareous nannofossil assemblage and compared it with variations in lithology and calculated sea surface temperature (SST) from previous studies. The Yorktown Formation in the studied sections consists of, in ascending order, the Sunken Meadow, Rushmere, Morgarts Beach, and Moore House members. Sediment samples were collected from these units and analyzed for calcareous nannoplankton assemblages. The last occurrences of both Reticulofenestra pseudoumbilicus (3.82 Ma) and Sphenolithus spp. (3.61 Ma) were recognized within the Sunken Meadow Member. Discoaster tamalis and Discoaster surculus sporadically occurred within the Rushmere Member, but no specimens of the genus Sphenolithus were recorded, suggesting that this unit was deposited sometime between 3.61–2.76Ma. Rare occurrences of the genus Discoaster made it difficult to constrain the age of the Morgarts Beach and Moore House members, but they are most likely deposited before re-entrance of small Gephyrocapsa (ca. 2.5 Ma), supporting previous age estimates based on planktic foraminiferal biostratigraphy and variation in alkenone-based sea-surface temperature estimates. The abrupt decline of both cold-water species ( Coccolithus pelagicus ) and coastal species ( Helicosphaera spp.) is associated with a rise in SST within the Rushmere Member just below the Morgarts Beach Member, and it may reflect a rapid transgression following the global sea-level low stand associated with Marine Isotope Stage (MIS)M2.

Virginia↗

USGS2021

Twenty-five essential research questions to inform the protection and restoration of freshwater biodiversity

Freshwater biodiversity is declining at an unprecedented rate. Freshwater conservationists and environmental managers have enough evidence to demonstrate that action must not be delayed but have insufficient evidence to identify those actions that will be most effective in reversing the current trend. Here, the focus is on identifying essential research topics that, if addressed, will contribute directly to restoring freshwater biodiversity through supporting ‘bending the curve’ actions (i.e. those actions leading to the recovery of freshwater biodiversity, not simply deceleration of the current downward trend). The global freshwater research and management community was asked to identify unanswered research questions that could address knowledge gaps and barriers associated with ‘bending the curve’ actions. The resulting list was refined into six themes and 25 questions. Although context-dependent and potentially limited in global reach, six overarching themes were identified: (i) learning from successes and failures; (ii) improving current practices; (iii) balancing resource needs; (iv) rethinking built environments; (v) reforming policy and investments; and (vi) enabling transformative change. Bold, efficient, science-based actions are necessary to reverse biodiversity loss. We believe that conservation actions will be most effective when supported by sound evidence, and that research and action must complement one another. These questions are intended to guide global freshwater researchers and conservation practitioners, identify key projects and signal research needs to funders and governments. Our questions can act as springboards for multidisciplinary and multisectoral collaborations that will improve the management and restoration of freshwater biodiversity.

Aquatic Conservation: Marine and Freshwater Ecosys↗

USGS2024

Post-fire reference densities for giant sequoia seedlings in a new era of high-severity wildfires

Many forests globally are experiencing increases in large, high-severity wildfires, often with increasingly inadequate post-fire tree regeneration. To identify areas that might need post-fire planting, forest managers have a growing need for seedling reference densities – the natural seedling densities expected to be adequate to regenerate a forest – to compare with observed post-fire seedling densities. The most useful reference densities will meet five criteria: they will (1) be specific to natural post-fire reproduction rather than planted seedlings (because planted seedlings can have substantially greater survival than natural seedlings, thus underestimating adequate natural reproduction), (2) apply to the first few years following fire (when management decisions and actions are most likely), (3) be specific to each of those post-fire years (because post-fire seedling densities can change rapidly with time since fire), (4) be associated with estimates of uncertainty, and (5) include consideration of novel environmental conditions during management applications (because most reference densities will be based on data collected under more environmentally benign conditions). The world’s most massive tree species, the giant sequoia ( Sequoiadendron giganteum ) of California’s Sierra Nevada, recently experienced historically unprecedented wildfires that killed an estimated 13–19% of mature sequoias across their native range. Seedlings germinating after these fires then experienced exceptional summer heat and the two most severe summer droughts of the 121-year historical record. To help inform management responses to these events, we used seedling censuses from past fires (mostly prescribed fires) to calculate sequoia seedling reference densities meeting the five criteria. The reference densities had three striking features, which are partly attributable to giant sequoia’s status as a pioneer species. First, despite being inherently conservative, the reference densities were quite high. For example, mean first-year reference density was 172,599 seedlings ha −1 . Second, reference densities declined precipitously with time since fire: the mean fifth-year reference density was only 5% of the mean first-year density. Third, the reference densities were associated with relatively substantial uncertainty, a consequence of density variations among seedling plots; for example, the 95% credible interval for first-year reference density was 64,377 to 313,438 seedlings ha −1 . Despite this uncertainty, a case-study sequoia grove that recently burned in a high-severity wildfire had second-year post-fire seedling densities that were significantly (and dramatically) lower than the corresponding second-year reference density, suggesting inadequate post-fire reproduction. Our results highlight the value of the five criteria for reference densities – criteria that, in current practice, are rarely all met.

Forest Ecology and Management↗