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

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At least 955 records · Page 53Linked to original sources
USGS2018

Comparison of microbiomes of cold-water corals Primnoa pacifica and Primnoa resedaeformis, with possible link between microbiome composition and host genotype

Cold-water corals provide critical habitats for a multitude of marine species, but are understudied relative to tropical corals. Primnoa pacifica is a cold-water coral prevalent throughout Alaskan waters, while another species in the genus, Primnoa resedaeformis , is widely distributed in the Atlantic Ocean. This study examined the V4-V5 region of the 16S rRNA gene after amplifying and pyrosequencing bacterial DNA from samples of these species. Key differences between the two species’ microbiomes included a robust presence of bacteria belonging to the Chlamydiales order in most of the P. pacifica samples, whereas no more than 2% of any microbial community from P. resedaeformis comprised these bacteria. Microbiomes of P. resedaeformis exhibited higher diversity than those of P. pacifica , and the two species largely clustered separately in a principal coordinate analysis. Comparison of P. resedaeformis microbiomes from samples collected in two submarine canyons revealed a significant difference between locations. This finding mirrored significant genetic differences among the P. resedaeformis from the two canyons based upon population genetic analysis of microsatellite loci. This study presents the first report of microbiomes associated with these two coral species.

Scientific Reports↗
USGS2018

Contribution of hurricane-induced sediment resuspension to coastal oxygen dynamics

Hurricanes passing over the ocean can mix the water column down to great depths and resuspend massive volumes of sediments on the continental shelves. Consequently, organic carbon and reduced inorganic compounds associated with these sediments can be resuspended from anaerobic portions of the seabed and re-exposed to dissolved oxygen (DO) in the water column. This process can drive DO consumption as sediments become oxidized. Previous studies have investigated the effect of hurricanes on DO in different coastal regions of the world, highlighting the alleviation of hypoxic conditions by extreme winds, which drive vertical mixing and re-aeration of the water column. However, the effect of hurricane-induced resuspended sediments on DO has been neglected. Here, using a diverse suite of datasets for the northern Gulf of Mexico, we find that in the few days after a hurricane passage, decomposition of resuspended shelf sediments consumes up to a fifth of the DO added to the bottom of the water column during vertical mixing. Despite uncertainty in this value, we highlight the potential significance of this mechanism for DO dynamics. Overall, sediment resuspension likely occurs over all continental shelves affected by tropical cyclones, potentially impacting global cycles of marine DO and carbon.

Scientific Reports↗
USGS2020

Morphological, elemental, and boron isotopic insights into pathophysiology of diseased coral growth anomalies

Growth anomalies (GAs) impact both coral skeleton and soft tissues and are detrimental to reef health. This tumor-like disease is increasingly found throughout the tropics and is commonly associated with high human population density, yet little is known about the etiology, pathology, or calcification behavior of the disease. Here, we investigate potential mechanisms involved in the development of GAs through chemical and morphological characterization of GA skeletons in Porites compressa from a site of high disease prevalence (Coconut Island, Hawaii). A comprehensive suite of trace elements and boron isotopes (δ11B) were measured in skeletal GAs to assess calcification behavior and uptake of essential and toxic metals. Scanning electron microscopy of GA skeleton revealed it to be highly porous consisting of a matrix with a disorganized crystal structure, in contrast to the dense well-organized normal skeleton of P. compressa. Elemental analyses revealed decreased Mg/Ca and increased U/Ca in GA skeletons relative to paired unaffected samples, suggesting a decreased abundance of rapidly accreting microstructures “centers of calcification” in the GAs. Estimates of carbonate system parameters based on δ11B and B/Ca measurements indicate reduced pH (–0.05 units) and [CO32–] within the calcifying fluid of GAs, which may have implications for GA calcification. Higher levels of essential (V/Ca and Mo/Ca) elements in GAs potentially indicate increased abundance of holobiont-associated, nitrogen-fixing bacteria and higher Sb/Ca and Nd/Ca indicate alteration in the accumulation/depuration of these toxic metals. In aggregate, our findings show that dystrophic calcification processes could explain structural differences seen in GA vs unaffected skeletons and highlight the use of approaches herein to shed light on disease pathophysiology in corals.

Scientific Reports↗
USGS2023

Upwelling, climate change, and the shifting geography of coral reef development

The eastern tropical Pacific is oceanographically unfavorable for coral-reef development. Nevertheless, reefs have persisted there for the last 7000 years. Rates of vertical accretion during the Holocene have been similar in the strong-upwelling Gulf of Panamá (GoP) and the adjacent, weak-upwelling Gulf of Chiriquí (GoC); however, seasonal upwelling in the GoP exacerbated a climate-driven hiatus in reef development in the late Holocene. The situation is now reversed and seasonal upwelling in the GoP currently buffers thermal stress, creating a refuge for coral growth. We developed carbonate budget models to project the capacity of reefs in both gulfs to keep up with future sea-level rise. On average, the GoP had significantly higher net carbonate production rates than the GoC. With an estimated contemporary reef-accretion potential (RAP) of 5.5 mm year −1 , reefs in the GoP are projected to be able to keep up with sea-level rise if CO 2 emissions are reduced, but not under current emissions trajectories. With an estimated RAP of just 0.3 mm year −1 , reefs in the GoC are likely already unable to keep up with contemporary sea-level rise in Panamá (1.4 mm year −1 ). Whereas the GoP has the potential to support functional reefs in the near-term, our study indicates that their long-term persistence will depend on reduction of greenhouse gases.

Scientific Reports↗
USGS2023

Intraspecific trait variability facilitates tree species persistence along riparian forest edges in Southern Amazonia

Tropical forest fragmentation from agricultural expansion alters the microclimatic conditions of the remaining forests, with effects on vegetation structure and function. However, little is known about how the functional trait variability within and among tree species in fragmented landscapes influence and facilitate species’ persistence in these new environmental conditions. Here, we assessed potential changes in tree species’ functional traits in riparian forests within six riparian forests in cropland catchments (Cropland) and four riparian forests in forested catchments (Forest) in southern Amazonia. We sampled 12 common functional traits of 123 species across all sites: 64 common to both croplands and forests, 33 restricted to croplands, and 26 restricted to forests. We found that forest-restricted species had leaves that were thinner, larger, and with higher phosphorus (P) content, compared to cropland-restricted ones. Tree species common to both environments showed higher intraspecific variability in functional traits, with leaf thickness and leaf P concentration varying the most. Species turnover contributed more to differences between forest and cropland environments only for the stem-specific density trait. We conclude that the intraspecific variability of functional traits (leaf thickness, leaf P, and specific leaf area) facilitates species persistence in riparian forests occurring within catchments cleared for agricultural expansion in Amazonia.

Scientific Reports↗
USGS2023

Evolutionary and ecological correlates of thiaminase in fishes

Thiamine (vitamin B 1 ) is required by all living organisms in multiple metabolic pathways. It is scarce in natural systems, and deficiency can lead to reproductive failure, neurological issues, and death. One major cause of thiamine deficiency is an overreliance on diet items containing the enzyme thiaminase. Thiaminase activity has been noted in many prey fishes and linked to cohort failure in salmonid predators that eat prey fish with thiaminase activity, yet it is generally unknown whether evolutionary history, fish traits, and/or environmental conditions lead to production of thiaminase. We conducted literature and GenBank BLAST sequence searches to collect thiaminase activity data and sequence homology data in expressed protein sequences for 300 freshwater and marine fishes. We then tested whether presence or absence of thiaminase could be predicted by evolutionary relationships, trophic level, omega-3 fatty acid concentrations, habitat, climate, invasive potential, and body size. There was no evolutionary relationship with thiaminase activity. It first appears in Class Actinoptergyii (bony ray-finned fishes) and is present across the entire Actinoptergyii phylogeny in both primitive and derived fish orders. Instead, ecological factors explained the most variation in thiaminase: fishes were more likely to express thiaminase if they fed closer to the base of the food web, were high in polyunsaturated fatty acids, lived in freshwater, and were from tropical climates. These data provide a foundation for understanding sources of thiaminase leading to thiamine deficiency in fisheries and other organisms, including humans that eat uncooked fish.

Scientific Reports↗
USGS2025

Modeling seawater intrusion along the Alabama coastline using physical and machine learning models to evaluate the effects of multiscale natural and anthropogenic stresses

Seawater intrusion threatens groundwater resources in coastal regions, including southern Baldwin County, Alabama, where the freshwater-saltwater interface dynamics remain poorly understood. To address this gap, this study uses combined physics-based and machine-learning models to quantify seawater intrusion caused by natural (storm surges) and anthropogenic (human activities) perturbations. The long short-term memory network and wavelet analysis were used to assess vertical aquifer vulnerabilities, revealing that the shallow part of the Coastal lowlands aquifer system (CL1) in the southern Baldwin County region is more susceptible to sea level rise and groundwater extraction than deeper aquifers. Based on these findings, a cross-sectional numerical model (physics approach) for the CL1 aquifer was developed to evaluate tidal and storm surge effects, using Tropical Storm Claudette (June 2021) as a case study. Results showed that tidal fluctuations had a minimal impact on the saltwater-freshwater interface location, whereas storm surges caused substantial inland movement, with effects lasting for nine months. The steady-state version of the three-dimensional (3D) physical model predicted seawater intrusion across the entire area, and convolutional neural network-based modeling further validated the model results. The 3D physical model was also applied to a smaller area to assess human impact on the saltwater interface due to two groundwater pumping scenarios (± 50% of the baseline pumping rate). Results revealed that a 50% increase in groundwater withdrawals caused seawater to advance ~ 320 m inland, whereas a 50% reduction led to a ~ 270-meter retreat. This study highlights the vulnerability of Alabama’s shallow coastal aquifers to seawater intrusion due to storm surges and human activities, and demonstrates that combining physics-based models with machine learning approaches can improve groundwater predictions, though its accuracy depends on the availability of site-specific data.

Alabama↗
USGS2024

Decomposition of physical processes controlling EASM precipitation changes during the mid-Piacenzian: New insights into data–model integration

The mid-Piacenzian warm period (MPWP, ~3.264–3.025 Ma) has gained widespread interest due to its partial analogy with future climate. However, quantitative data–model comparison of East Asian Summer Monsoon (EASM) precipitation during the MPWP is relatively rare, especially due to problems in decoding the imprint of physical processes to climate signals in the records. In this study, pollen-based precipitation records are reconstructed and compared to the multi-model ensemble mean of the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). We find spatially consistent precipitation increase in most simulations but a spatially divergent change in MPWP records. We reconcile proxy data and simulation by decomposing physical processes that control precipitation. Our results 1) reveal thermodynamic control of an overall enhancement of EASM precipitation and 2) highlight a distinct control of thermodynamic and dynamical processes on increases of tropical and subtropical EASM precipitation, reflecting the two pathways of water vapor supply that enhance EASM precipitation, respectively.

npj Climate and Atmospheric Science↗
USGS2024

Wind-wave climate changes and their impacts

Wind-waves have an important role in Earth system dynamics through air–sea interactions and are key drivers of coastal and offshore hydro-morphodynamics that affect communities, ecosystems, infrastructure and operations. In this Review, we outline historical and projected changes in the wind-wave climate over the world’s oceans, and their impacts. Historical trend analysis is challenging owing to the presence of temporal inhomogeneities from increased numbers and types of assimilated data. Nevertheless, there is general agreement over a consistent historical increase in mean wave height of 1–3 cm yr −1 in the Southern and Arctic Oceans, with extremes increasing by >10 cm yr −1 for the latter. By 2100, mean wave height is projected to rise by 5–10% in the Southern Ocean and eastern tropical South Pacific, and by >100% in the Arctic Ocean. By contrast, reductions in mean wave height up to 10% are expected in the North Atlantic and North Pacific, with regional variability and uncertainty for changes in extremes. Differences between 1.5 °C and warmer worlds reveal the potential benefit of limiting anthropogenic warming. Resolving global-scale climate change impacts on coastal processes and atmospheric–ocean–wave interactions requires a step-up in observational and modeling capabilities, including enhanced spatiotemporal resolution and coverage of observations, more homogeneous data products, multidisciplinary model improvement, and better sampling of uncertainty with larger ensembles.

Nature Reviews Earth & Environment↗
USGS2026

Persistence of coral reef structures into the twenty-first century

Coral reefs provide important socioecological services but are vulnerable to climate change, which shifts the balance between the production and erosion of calcium carbonate (CaCO 3 ). In this Review, we summarize understanding of reef accretion, describe the mechanisms of carbonate production and erosion, and consider the effects of future ocean warming and acidification on key reef-building and eroding taxa. The combined stressors of climate change substantially reduce net carbonate production, with a more pronounced effect on calcifying algae than corals. However, declining coral cover driven by marine heatwaves and mass bleaching will probably be the dominant determinant of future reef carbonate budgets, and thus only reefs with thermally adapted populations are predicted to maintain the ability to sustain positive CaCO 3 production under climate change, even if calcareous algal cover increases. As carbonate budgets become net negative in the future, the longevity of pre-existing reef frameworks remains unknown and understudied owing to the timescales required to meaningfully assess framework removal rates. Improving estimates of the rates of biologically driven framework loss and chemical dissolution will also be important in better predicting future reef persistence. Key knowledge gaps exist in understanding the effects of deoxygenation on coral reefs, as well as the influence of climate change on understudied sediment-producing taxa such as foraminifera and tropical molluscs.

Nature Reviews Earth & Environment↗
USGS2024

Modern coral range expansion off southeast Florida falls short of Late Holocene baseline

As thermal stress and disease outbreaks decimate coral reefs throughout the tropics, there is growing evidence that higher latitude marine environments may provide crucial refuges for many at-risk, temperature-sensitive coral species. However, our understanding of how coral populations expand into new areas and sustain themselves over time is constrained by the limited scope of modern observations. Here, we provide geological insights into coral range expansions by reconstructing the composition of a Late Holocene-aged subfossil coral death assemblage on the southeast Florida reef tract and comparing it to modern reefs throughout the region. Our findings show that the Late Holocene coral assemblages were dominated by now critically endangered Acropora species between ~3500 and 1800 years before present, mirroring classic zonation patterns characteristic of healthy pre-1970s Caribbean reefs. In contrast, the modern reefs off southeast Florida are becoming increasingly dominated by stress-tolerant species like Porites astreoides and Siderastrea siderea despite modest expansions of Acropora cervicornis over the past several decades. Our results suggest that ongoing anthropogenic stressors, not present during the Late Holocene, are likely limiting the ability of modern higher latitude reefs in Florida to function as long-term climate refugia.

Florida↗
USGS2014

The carbon cycle and hurricanes in the United States between 1900 and 2011

Hurricanes cause severe impacts on forest ecosystems in the United States. These events can substantially alter the carbon biogeochemical cycle at local to regional scales. We selected all tropical storms and more severe events that made U.S. landfall between 1900 and 2011 and used hurricane best track database, a meteorological model (HURRECON), National Land Cover Database (NLCD), U. S. Department of Agirculture Forest Service biomass dataset, and pre- and post-MODIS data to quantify individual event and annual biomass mortality. Our estimates show an average of 18.2 TgC/yr of live biomass mortality for 1900–2011 in the US with strong spatial and inter-annual variability. Results show Hurricane Camille in 1969 caused the highest aboveground biomass mortality with 59.5 TgC. Similarly 1954 had the highest annual mortality with 68.4 TgC attributed to landfalling hurricanes. The results presented are deemed useful to further investigate historical events, and the methods outlined are potentially beneficial to quantify biomass loss in future events.

Scientific Reports↗
USGS2015

Many atolls may be uninhabitable within decades due to climate change

Observations show global sea level is rising due to climate change, with the highest rates in the tropical Pacific Ocean where many of the world’s low-lying atolls are located. Sea-level rise is particularly critical for low-lying carbonate reef-lined atoll islands; these islands have limited land and water available for human habitation, water and food sources, and ecosystems that are vulnerable to inundation from sea-level rise. Here we demonstrate that sea-level rise will result in larger waves and higher wave-driven water levels along atoll islands’ shorelines than at present. Numerical model results reveal waves will synergistically interact with sea-level rise, causing twice as much land forecast to be flooded for a given value of sea-level rise than currently predicted by current models that do not take wave-driven water levels into account. Atolls with islands close to the shallow reef crest are more likely to be subjected to greater wave-induced run-up and flooding due to sea-level rise than those with deeper reef crests farther from the islands’ shorelines. It appears that many atoll islands will be flooded annually, salinizing the limited freshwater resources and thus likely forcing inhabitants to abandon their islands in decades, not centuries, as previously thought.

Hawaii↗
USGS2001

Comparing global models of terrestrial net primary productivity (NPP): Global pattern and differentiation by major biomes

Annual and seasonal net primary productivity estimates (NPP) of 15 global models across latitudinal zones and biomes are compared. The models simulated NPP for contemporary climate using common, spatially explicit data sets for climate, soil texture, and normalized difference vegetation index (NDVI). Differences among NPP estimates varied over space and time. The largest differences occur during the summer months in boreal forests (50??to 60??N) and during the dry seasons of tropical evergreen forests. Differences in NPP estimates are related to model assumptions about vegetation structure, model parameterizations, and input data sets.

Global Change Biology↗
USGS2012

11 things a geologist thinks an engineer should know about carbonate beaches

This is a review of the geological aspects of carbonate beaches that a geologist thinks may be useful for an engineer. Classical geologic problems of carbonate beaches, for example how ancient examples are recognized in rock sequences, are of little interest to engineers. Geologists not involved in engineering problems may find it difficult to know what an engineer should understand about carbonate beaches. Nevertheless, there are at least eleven topics that are potentially very useful for engineers to keep in mind. These eleven are chosen with as much thought going into what has been omitted as has been given to the eleven included topics. Some qualifications are in order: First, this paper does not discuss certain kinds of carbonate shorelines that are beyond the scope of engineering issues. For example, this review does not discuss very high-energy carbonate boulder beaches. These beaches are comprised of pieces of carbonate material ganging in size from ten centimeters to meters. Typically, these are high-energy storm deposits formed from pieces of either eroded carbonate rock or other large carbonate pieces such as pieces of large corals. This paper focuses on sand-sized (0.0625–2.0 mm) coastal carbonate deposits. Second, offshore beaches will not be discussed. There are many carbonate beaches that form on banks or shoals exposed at low tide, but our discussion is confined to what most people think of when they go to some tropical island and/or resort and walk out to lay on the beach. Third, this paper does not consider mixed carbonate/quartz sand beaches. While mixed beaches are common, only the end member of purely carbonate sand beaches is considered. Fourth, there will be no order of preference of the eleven topics. And lastly, these eleven topics are not consensus items. These are simply one geologist s thoughts about the aspects of carbonate beaches that would be useful for engineering colleagues to keep in mind. Where possible, general reference is made to textbooks that will lead the reader to extensive literature on carbonate sediments. Several of the topics are not so broad as to have had a large general treatment in texts, and in those cases some original literature is cited.

Conference Paper↗
USGS2001

El Niño and its impact on fire weather conditions in Alaska

Examining the relationship of El Niño to weather patterns in Alaska shows wide climate variances that depend on the teleconnection between the tropics and the northern latitudes. However, the weather patterns exhibited in Alaska during and just after moderate to strong El Niño episodes are generally consistent: above normal temperature and precipitation along the Alaskan coast, and above normal temperature and below normal precipitation in the interior, especially through the winter. The warm, dry conditions in the Alaskan interior increase summer wildfire potential. Statistics on the area burned since 1940 show that 15 out of 17 of the biggest fire years occurred during a moderate to strong El Niño episode. These 15 years account for nearly 63% of the total area burned over the last 58 years. Evidence points to increased dry thunderstorms and associated lightning activity during an El Niño episode; the percentage of total area burned by lightning caused fires during five episodes increased from a normal of less than 40% to a high of about 96%.

International Journal of Wildland Fire↗
USGS2022

The effect of scent lures on detection is not equitable among sympatric species

Context: Camera trapping is an effective tool for cost-efficient monitoring of species over large temporal and spatial scales and it is becoming an increasingly popular method for investigating wildlife communities and trophic interactions. However, camera trapping targeting rare and elusive species can be hampered by low detection rates, which can decrease the accuracy and precision of results from common analytical approaches (e.g., occupancy modeling, capture-recapture). Consequently, researchers often employ attractants to increase detection without accounting for how attractants influence detection of species among trophic levels. Aims: We aimed to evaluate the influences of a commonly used non-species-specific olfactory lure (i.e. sardines) and sampling design on detection of four species (i.e. bobcat [ Lynx rufus ], coyote [ Canis latrans ], raccoon [ Procyon lotor ], and eastern cottontail [ Sylvilagus floridanus ]) that represented a range of foraging guilds in an agricultural landscape. Methods: We set 180 camera stations, each for ∼28 days, during the summer of 2019. We set cameras with one of three lure treatments: (1) olfactory lure, (2) no olfactory lure, or (3) olfactory lure only during the latter half of the survey. We evaluated the influence of the lure at three temporal scales of detection (i.e. daily probability of detection, independent sequences per daily detection, and triggers per independent sequence). Key results: The lure tended to positively influence detection of coyotes and raccoons but negatively influenced detection of bobcats and eastern cottontails. The influence of the lure varied among temporal scales of detection. Conclusions: Scent lures can differentially influence detection of species within or among tropic levels, and the influence of a scent lure may vary among temporal scales. Implications: Our results demonstrate the importance of evaluating the influence of an attractant for each focal species when using camera data to conduct multi-species or community analyses, accounting for variation in sampling strategies across cameras, and identifying the appropriate species-specific temporal resolution for assessing variation in detection data. Furthermore, we highlight that care should be taken when using camera data as an index of relative abundance (e.g. as is commonly done with prey species) when there is variation in the use of lures across cameras.

Wildlife Research↗
USGS2004

Pacific and Atlantic Ocean influences on multidecadal drought frequency in the United States

More than half (52%) of the spatial and temporal variance in multidecadal drought frequency over the conterminous United States is attributable to the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). An additional 22% of the variance in drought frequency is related to a complex spatial pattern of positive and negative trends in drought occurrence possibly related to increasing Northern Hemisphere temperatures or some other unidirectional climate trend. Recent droughts with broad impacts over the conterminous U.S. (1996, 1999-2002) were associated with North Atlantic warming (positive AMO) and north-eastern and tropical Pacific cooling (negative PDO). Much of the long-term predictability of drought frequency may reside in the multidecadal behavior of the North Atlantic Ocean. Should the current positive AMO (warm North Atlantic) conditions persist into the upcoming decade, we suggest two possible drought scenarios that resemble the continental-scale patterns of the 1930s (positive PDO) and 1950s (negative PDO) drought.

Proceedings of the National Academy of Sciences of↗