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USGS2016

Seasonal flows of international British Columbia-Alaska rivers: The nonlinear influence of ocean-atmosphere circulation patterns

The northern portion of the Pacific coastal temperate rainforest (PCTR) is one of the least anthropogenically modified regions on earth and remains in many respects a frontier area to science. Rivers crossing the northern PCTR, which is also an international boundary region between British Columbia, Canada and Alaska, USA, deliver large freshwater and biogeochemical fluxes to the Gulf of Alaska and establish linkages between coastal and continental ecosystems. We evaluate interannual flow variability in three transboundary PCTR watersheds in response to El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Arctic Oscillation (AO), and North Pacific Gyre Oscillation (NPGO). Historical hydroclimatic datasets from both Canada and the USA are analyzed using an up-to-date methodological suite accommodating both seasonally transient and highly nonlinear teleconnections. We find that streamflow teleconnections occur over particular seasonal windows reflecting the intersection of specific atmospheric and terrestrial hydrologic processes. The strongest signal is a snowmelt-driven flow timing shift resulting from ENSO- and PDO-associated temperature anomalies. Autumn rainfall runoff is also modulated by these climate modes, and a glacier-mediated teleconnection contributes to a late-summer ENSO-flow association. Teleconnections between AO and freshet flows reflect corresponding temperature and precipitation anomalies. A coherent NPGO signal is not clearly evident in streamflow. Linear and monotonically nonlinear teleconnections were widely identified, with less evidence for the parabolic effects that can play an important role elsewhere. The streamflow teleconnections did not vary greatly between hydrometric stations, presumably reflecting broad similarities in watershed characteristics. These results establish a regional foundation for both transboundary water management and studies of long-term hydroclimatic and environmental change.

Alaska, British Columbia↗

USGS2004

Formation, evolution, and stability of coastal cliffs: Status and trends

The Ocean Studies Board of the National Research Council recently reviewed the U.S. Geological Survey's Coastal and Marine Geology (USGS-CMG) program. One of the Board's primary recommendations was that CMG prepare comprehensive assessments of the nation's coastal and marine regions, drawing on expertise not only from within the USGS, but also from outside agencies and academic institutions. In response to that recommendation, this report assesses the status and trends of coastal cliffs along the shorelines of the conterminous United States and the Great Lakes. By "status" is meant the present distribution and character of coastal cliffs, as well as their current relevance to social issues such as coastal development. By "trends" is meant the changes in status caused by both geological forces and human activities. Coastal cliffs are steep escarpments at the coastline. They commonly form during times of rising sea level, such as the present, as the shoreline advances landward and erodes the elevated landmass. Coastal cliffs are a common landform, particularly on the west, northeast, and Great Lakes coasts of the United States, as well as within large estuaries. The land adjacent to coastal cliffs has been heavily developed along much of the coast, particularly in urban areas where the natural instability and progressive retreat of the cliffs pose a threat to life and property. Coastal land is permanently lost when coastal cliffs collapse and retreat landward, which is an important national issue in coastal planning, management, and engineering. The content of this report was derived from the personal expertise of the authors and from the extensive scientific literature concerned with coastal cliffs. As a report to the Nation, it is intended for a broad audience. Both topical and regional aspects are presented. It is important to recognize that the emphasis of this report is on the geology of coastal cliffs; engineering, land-use, and regulatory issues are addressed only where there is a clear link to the geologic nature of coastal cliffs. The editors appreciate the thorough and careful review of the entire manuscript by Alan Trenhaile and Laura Moore. Their editing, comments, and questions greatly improved the content and clarity of the final report.

Professional Paper↗

USGS2010

Kittlitz’s and Marbled Murrelets in Kenai Fjords National Park, south-central Alaska: At-sea distribution, abundance, and foraging habitat, 2006–08

Kittlitz’s murrelets ( Brachyramphus brevirostris ) and marbled murrelets ( B. marmoratus ) are small diving seabirds and are of management concern because of population declines in coastal Alaska. In 2006–08, we conducted a study in Kenai Fjords National Park, south-central Alaska, to estimate the recent population size of Brachyramphus murrelets, to evaluate productivity based on juvenile to adult ratios during the fledgling season, and to describe and compare their use of marine habitat. We also attempted a telemetry study to examine Kittlitz’s murrelet nesting habitat requirements and at-sea movements. We estimated that the Kittlitz’s murrelet population was 671 ± 144 birds, and the marbled murrelet population was 5,855 ± 1,163 birds. Kittlitz’s murrelets were limited to the heads of three fjords with tidewater glaciers, whereas marbled murrelets were more widely distributed. Population estimates for both species were lower in 2007 than in 2006 and 2008, possibly because of anomalous oceanographic conditions that may have delayed breeding phenology. During late season surveys, we observed few hatch-year marbled murrelets and only a single hatch-year Kittlitz’s murrelet over the course of the study. Using radio telemetry, we found a likely Kittlitz’s murrelet breeding site on a mountainside bordering one of the fjords. We never observed radio-tagged Kittlitz’s murrelets greater than 10 kilometer from their capture sites, suggesting that their foraging range during breeding is narrow. We observed differences in oceanography between fjords, reflecting differences in sill characteristics and orientation relative to oceanic influence. Acoustic biomass, a proxy for zooplankton and small schooling fish, generally decreased with distance from glaciers in Northwestern Lagoon, but was more variable in Aialik Bay where dense forage fish schools moved into glacial areas late in the summer. Pacific herring ( Clupea pallasii ), capelin ( Mallotus villosus ) and Pacific sand lance ( Ammodytes hexapterus ) were important forage species for murrelets in Kenai Fjords. Euphausiids also may have been an important forage resource for Kittlitz’s murrelets in turbid glacial outflows in shallow waters during daytime. Marbled murrelets generally were more tolerant to a wider range of foraging habitat conditions although they tended to avoid the ice-covered silty waters close to glaciers. In contrast, Kittlitz’s murrelets preferred areas where the influence of tidewater glaciers was the greatest and where their distribution was determined largely by prey availability. This work highlights an important link between interannual variability in murrelet counts at sea and mesoscale oceanographic conditions that influence marine productivity and prey distribution.

Open-File Report↗

USGS2007

Effect of storms on barrier island dynamics, Core Banks, Cape Lookout National Seashore, North Carolina, 1960-2001

The effect of storms on long-term dynamics of barrier islands was evaluated on Core Banks, a series of barrier islands that extend from Cape Lookout to Okracoke Inlet in the Cape Lookout National Seashore, North Carolina. Shoreline and elevation changes were determined by comparing 77 profiles and associated reference markers established by the U.S. Army Corps of Engineers (USACE) on Core Banks from June 1960 to July 1962 to a follow-up survey by Godfrey and Godfrey (G&G) in 1971 and a survey by the Department of Geology at East Carolina University (ECU) in 2001, in which 57 of the original 77 profiles were located. Evaluation of the baseline data associated with the USACE study supplies an important record of barrier island response to two specific storm events—Hurricane Donna in September 1960 and the Ash Wednesday extra-tropical cyclone in March 1962. The 1962 USACE survey was followed by 9 years characterized by no major storms; this low-energy period was captured by the G&G survey in 1971. The G&G survey was followed by 22 years characterized by occasional small to moderate storms. Starting in 1993, however, and continuing through 1999, the North Carolina coast experienced a major increase in storm activity, with seven major hurricanes impacting Core Banks. Both the USACE 1960–1962 and G&G 1962–1971 surveys produced short-term data sets that reflected very different sets of weather conditions. The ECU 2001 survey data were then compared with the USACE 1960 survey data to develop a long-term (41 years) data set for shoreline erosion on Core Banks. Those resulting long-term data were compared with the long-term (52 years) data sets by the North Carolina Division of Coastal Management (NCDCM) from 1940–1992 and 1946–1998; a strong positive correlation and very similar rates of average annual erosion resulted. However, the ECU and NCDCM long-term data sets did not correlate with either of the USACE and G&G short-term survey data and had very different average annual erosion rates. The average annual long-term rate of shoreline erosion for all of Core Banks and for both the ECU 1960–2001 and the NCDCM 1946–1998 surveys was -5 feet per year (ft/yr). These long-term rates of shoreline recession are in strong contrast with the short-term, storm-dominated rates of shoreline erosion for all of Core Banks developed by the USACE 1960–1961 and USACE 1961–1962 surveys, which have average annual erosion rates of -40 ft/yr and -26 ft/yr, respectively, and range from -226 feet (ft) to +153 ft. The combined short-term, storm-dominated shoreline erosion rate for the USACE surveys (1960–1962) was -36 ft/yr. In contrast, the average annual short-term, non-stormy period G&G 1962–1971 survey demonstrated shoreline accretion for all of Core Banks with an average annual rate of +12 ft/yr. In general, North Core Banks has higher erosion and accretion rates than South Core Banks. In the 1961 survey, the USACE installed 231 reference markers (RM-0 is closest to the ocean and RM-2 is farthest from the ocean) along the 77 profiles, as well as 33 reference markers labeled RM-4, RM-6, and RM-8 in the wider portions of the islands. The G&G survey recovered a total of 141 reference markers (61 percent), and the ECU survey recovered a total of 83 reference markers (36 percent) of the RM-0, RM-1, and RM-2 markers. The average ground elevation measured by the USACE in 1961 was RM-0 = +5.8 ft, RM-1 = +5.2 ft, and RM-2 = +4.8 ft. The G&G 1970 survey measured average ground elevations of RM-0 = +6.7 ft, RM-1 = +6.4 ft, and RM-2 = +6.1 ft, and the average ground elevation measured by ECU in 2001 was RM-0 = +10.1 ft, RM-1 = +9.1 ft, and RM-2 = +8.5 ft. The latter numbers represent approximately an overall 72-percent increase in island elevation from 1961 to 2001. Based on aerial photographic time-slice analyses, it is hypothesized that this increase in island elevation occurred during the post-1962 period with storm overwash systematically raising the island elevation through time, which in turn led to decreased numbers of overwash events. The latter processes and responses in turn led to a substantial increase in vegetative growth on the barrier island, as well as submerged aquatic vegetation on the back-barrier sand shoals. Integration of the USACE, G&G, ECU, and NCDCM shoreline erosion data for Core Banks shows several important points about shoreline recession. (1) The ECU and NCDCM data sets demonstrate that there is an ongoing net, long-term, but small-scale shoreline recession associated with Core Banks; (2) the USACE short-term data sets demonstrate that processes associated with individual storm events or sets of events produce extremely large-scale changes that include both erosion and accretion; (3) the short-term, non-stormy period data set of G&G demonstrates that if given enough time between storm events, barriers can rebuild to their pre-storm period conditions; and (4) the post-storm response generally tends to approach the pre-storm location, but rarely reaches it before the next storm or stormy period sets in. The result is the net long-term change documented by both the ECU 1960–2001 and NCDCM 1946–1998 Core Banks data sets that resulted in erosion rates ranging from 0 to -30 ft/yr with net annual average recession rates of -5 ft/yr. Analysis and comparison of these data sets supply important information for understanding the dynamics and responses of barrier island systems through time. In addition, the results of the present study on Core Banks supply essential process-response information that can be used to design and implement management plans for the Cape Lookout and Cape Hatteras National Seashores and for other seashores in the U.S. National Park Service system.

North Carolina↗

USGS1997

California salmon and steelhead: Beyond the crossroads

Virtually all California salmon (Oncorhynchus spp.) and steelhead (O. mykiss) stocks have declined to record or near-record low levels during 1980-95. Escapement of naturally spawning Klamath and Sacramento basin fall-run chinook salmon (O. tshawytscha) stocks has fallen consistently below the goals of 35,000 adults (Klamath) and 120,000 adults (Sacramento) established by the Pacific Fishery Management Council. These two stocks constitute the primary management units for ocean harvest regulations in California and southern Oregon. This decline triggered a mandatory review of ocean harvest and inland production conditions in each basin. The Sacramento winter-run chinook salmon, once numbering >100,000 adult spawners, was listed as threatened in 1990 and endangered in 1994 under the Endangered Species Act. The listing occurred as a result of a precipitous decline in abundance (to <200 adult spawners) and significant threats to this stock’s continued existence. Spring-run chinook salmon, historically an abundant component of California’s inland fish fauna with >500,000 adult spawners, has been extirpated from the San Joaquin River basin. However, remnant populations of this naturally spawning stock remain within the Klamath, Smith, and Sacramento river basins. Unfortunately, annual counts of 3,000-25,000 spawners in the Sacramento River basin during the past 25 years are largely of hatchery origin. Recent steelhead data from the same region indicate that many stocks are close to extinction, and nearly all steel-head in the Sacramento River are also of hatchery origin. Both spring-run chinook salmon and summer steelhead are considered to be species of special concern by the California Department of Fish and Game because of their limited distributions and sensitivities to degraded habitat conditions. The southern race of winter steelhead south of Point Conception is nearly extinct and remnant populations have been recently recorded in only 9 streams. Coastal cutthroat trout (O. clarki) , which are restricted to lowland drainages from the Eel River northward, are greatly depleted. Coho salmon (O. kisutch) ,which once probably numbered close to 1,000,000 fish per year in coastal California streams, have dwindled to —5,000 natural spawners per year. Chum salmon (O. keta) , never a significant part of the state’s native fish fauna, are currently restricted to <10 spawners in three different streams in the Sacramento River basin and occasionally in the South Fork of the Trinity River. The historically small runs of pink salmon (O. gorbuscha) in the Sacramento and Russian rivers are probably now extirpated. Anadromous sockeye salmon (O. nerka) are only recorded as strays. In response to serious declines in salmon and steelhead stocks, numerous legislative and congressional actions have been undertaken and California has embarked on an ambitious planto restore riparian habitats, improve fish passage, and increase natural production. Additionally, many currently unlisted California salmon and steelhead stocks are potential candidates for protection under the Endangered Species Act. These include coho, chum, spring-run chinook, and San Joaquin fall-run chinook salmon, as well as summer steelhead and the southern race of winter steelhead.

Book chapter↗

USGS2014

Diverse coral communities in mangrove habitats suggest a novel refuge from climate change

Risk analyses indicate that more than 90% of the world's reefs will be threatened by climate change and local anthropogenic impacts by the year 2030 under "business-as-usual" climate scenarios. Increasing temperatures and solar radiation cause coral bleaching that has resulted in extensive coral mortality. Increasing carbon dioxide reduces seawater pH, slows coral growth, and may cause loss of reef structure. Management strategies include establishment of marine protected areas with environmental conditions that promote reef resiliency. However, few resilient reefs have been identified, and resiliency factors are poorly defined. Here we characterize the first natural, non-reef coral refuge from thermal stress and ocean acidification and identify resiliency factors for mangrove–coral habitats. We measured diurnal and seasonal variations in temperature, salinity, photosynthetically active radiation (PAR), and seawater chemistry; characterized substrate parameters; and examined water circulation patterns in mangrove communities where scleractinian corals are growing attached to and under mangrove prop roots in Hurricane Hole, St. John, US Virgin Islands. Additionally, we inventoried the coral species and quantified incidences of coral bleaching, mortality, and recovery for two major reef-building corals, Colpophyllia natans and Diploria labyrinthiformis , growing in mangrove-shaded and exposed (unshaded) areas. Over 30 species of scleractinian corals were growing in association with mangroves. Corals were thriving in low-light (more than 70% attenuation of incident PAR) from mangrove shading and at higher temperatures than nearby reef tract corals. A higher percentage of C. natans colonies were living shaded by mangroves, and no shaded colonies were bleached. Fewer D. labyrinthiformis colonies were shaded by mangroves, however more unshaded colonies were bleached. A combination of substrate and habitat heterogeneity, proximity of different habitat types, hydrographic conditions, and biological influences on seawater chemistry generate chemical conditions that buffer against ocean acidification. This previously undocumented refuge for corals provides evidence for adaptation of coastal organisms and ecosystem transition due to recent climate change. Identifying and protecting other natural, non-reef coral refuges is critical for sustaining corals and other reef species into the future.

Biogeosciences↗

USGS2023

Accuracy of shoreline forecasting using sparse data

Sandy beaches are important resources providing recreation, tourism, habitat, and coastal protection. They evolve over various time scales due to local winds, waves, storms, and changes in sea level. A common method used to monitor change in sandy beaches is to measure the movement of the shoreline over time. Typically, the rate of change is estimated by fitting a linear regression through a time series of shoreline positions. To best manage the valuable resources within a coastal environment, accurate forecasts of shoreline position are needed. A simple way to estimate future shoreline position is to extrapolate a linear regression into the future, this method is often used to establish management guidelines like construction setback lines. A more recently developed shoreline forecasting technique utilizes the Kalman filter to assimilate shoreline data and modify the linear regression. This paper calculates the uncertainty and accuracy of both the extrapolated linear regression and Kalman filter forecasting methods for 10- and 20-year hindcasts using data collected at five diverse study areas. These data are inherently sparse (8–10 measurements per location, collected over 150 years) and are representative of the observed historical data available for the continental United States for this timeframe. Both methods produced similar results and had regionally averaged forecast accuracies of 5–16 m. We determined that the inaccuracy of the forecasts is largely due to the effects of shorter time scale variability. This variability is roughly proportional to the standard error of the linear regression, which is a useful measure of forecast uncertainty.

Florida, Georgia, Massachusetts↗

USGS2017

Five-year external reviews of the eight Department of Interior Climate Science Centers: Southeast Climate Science Center

In 2008, the U.S. Congress authorized the establishment of the National Climate Change and Wildlife Science Center (NCCWSC) within the U.S. Department of Interior (DOI). Housed administratively within the U.S. Geological Survey (USGS), NCCWSC is part of the DOI’s ongoing mission to meet the challenges of climate change and its effects on wildlife and aquatic resources. From 2010 through 2012, NCCWSC established eight regional DOI Climate Science Centers (CSCs). Each of these regional CSCs operated with the mission to “synthesize and integrate climate change impact data and develop tools that the Department’s managers and partners can use when managing the Department’s land, water, fish and wildlife, and cultural heritage resources” (Salazar 2009). The model developed by NCCWSC for the regional CSCs employed a dual approach of a federal USGS-staffed component and a parallel host-university component established competitively through a 5-year cooperative agreement with NCCWSC. At the conclusion of this 5-year agreement, a review of each CSC was undertaken, with the Southeast Climate Science Center (SE CSC) review in February 2016. The SE CSC is hosted by North Carolina State University (NCSU) in Raleigh, North Carolina, and is physically housed within the NCSU Department of Applied Ecology along with the Center for Applied Aquatic Ecology, the North Carolina Cooperative Fish and Wildlife Research Unit (CFWRU), and the North Carolina Agromedicine Institute. The U.S. Department of Agriculture Southeast Regional Climate Hub is based at NCSU as is the National Oceanic and Atmospheric Administration (NOAA) Southeast Regional Climate Center, the North Carolina Institute for Climate Studies, the North Carolina Wildlife Resources Commission, the NOAA National Weather Service, the State Climate Office of North Carolina, and the U.S. Forest Service Eastern Forest Environmental Threat Assessment Center. This creates a strong core of organizations operating in close proximity focused on climate issues. The geographic area covered by the SE CSC represents all or part of 16 states and the Caribbean Islands and has overlapping boundaries with seven Landscape Conservation Cooperatives (LCCs): Appalachian LCC, Eastern Tallgrass Prairie and Big Rivers LCC, Gulf Coast Prairie LCC, Gulf Coastal Plains and Ozarks LCC, Peninsular Florida LCC, South Atlantic LCC, and Caribbean LCC. The SE CSC region also encompasses 134 U.S. Fish and Wildlife Service refuges and 89 National Park Service (NPS) units and is home to 11 federally recognized and 54 state recognized tribes.

Report↗

USGS2004

Integrating digital information for coastal and marine sciences

A pilot distributed geolibrary, the Marine Realms Information Bank (MRIB), was developed by the U.S. Geological Survey Coastal and Marine Geology Program and the Woods Hole Oceanographic Institution, to classify, integrate, and facilitate access to scientific information about oceans, coasts, and lakes. The MRIB is composed of a categorization scheme, a metadata database, and a specialized software backend, capable of drawing together information from remote sources without modifying their original format or content. Twelve facets are used to classify information: location, geologic time, feature type, biota, discipline, research method, hot topics, project, agency, author, content type, and file type. The MRIB approach allows easy and flexible organization of large or growing document collections for which centralized repositories would be impractical. Geographic searching based on the gazetteer and map interface is the centerpiece of the MRIB distributed geolibrary. The MRIB is one of a very few digital libraries that employ georeferencing -- a fundamentally different way to structure information from the traditional author/title/subject/keyword approach employed by most digital libraries. Lessons learned in developing the MRIB will be useful as other digital libraries confront the challenges of georeferencing.

Journal of Digital Information Management↗

USGS2008

Global daily reference evapotranspiration modeling and evaluation

Accurate and reliable evapotranspiration (ET) datasets are crucial in regional water and energy balance studies. Due to the complex instrumentation requirements, actual ET values are generally estimated from reference ET values by adjustment factors using coefficients for water stress and vegetation conditions, commonly referred to as crop coefficients. Until recently, the modeling of reference ET has been solely based on important weather variables collected from weather stations that are generally located in selected agro-climatic locations. Since 2001, the National Oceanic and Atmospheric Administration’s Global Data Assimilation System (GDAS) has been producing six-hourly climate parameter datasets that are used to calculate daily reference ET for the whole globe at 1-degree spatial resolution. The U.S. Geological Survey Center for Earth Resources Observation and Science has been producing daily reference ET (ETo) since 2001, and it has been used on a variety of operational hydrological models for drought and streamflow monitoring all over the world. With the increasing availability of local station-based reference ET estimates, we evaluated the GDAS-based reference ET estimates using data from the California Irrigation Management Information System (CIMIS). Daily CIMIS reference ET estimates from 85 stations were compared with GDAS-based reference ET at different spatial and temporal scales using five-year daily data from 2002 through 2006. Despite the large difference in spatial scale (point vs . ∼100 km grid cell) between the two datasets, the correlations between station-based ET and GDAS-ET were very high, exceeding 0.97 on a daily basis to more than 0.99 on time scales of more than 10 days. Both the temporal and spatial correspondences in trend/pattern and magnitudes between the two datasets were satisfactory, suggesting the reliability of using GDAS parameter-based reference ET for regional water and energy balance studies in many parts of the world. While the study revealed the potential of GDAS ETo for large-scale hydrological applications, site-specific use of GDAS ETo in complex hydro-climatic regions such as coastal areas and rugged terrain may require the application of bias correction and/or disaggregation of the GDAS ETo using downscaling techniques.

Journal of the American Water Resources Associatio↗

USGS2018

Analysis of multi-decadal wetland changes, and cumulative impact of multiple storms 1984 to 2017

Land-cover classification analysis using Landsat satellite imagery acquired between 1984 and 2017 quantified short- (post-Hurricane Sandy) and long-term wetland-change trends along the Maryland and Virginia coasts between Metompkin Bay, VA and Ocean City, MD. Although there are limited options for upland migration of wetlands in the study area, regression analysis showed that wetland area increased slightly between 1984 and 2011, indicating that marsh aggradation rates were sufficient to maintain wetland elevation relative to mean sea level. Following Hurricane Irene (August 2011), the Halloween Nor’Easter (October 2011), and Hurricane Sandy (October 2012), wetland area decreased by more than 7 km 2 compared with average pre-storm extents. We assume that Hurricane Sandy had the greatest impact due to the size and intensity of the storm. However, the cumulative effects of multiple storms within a short time period likely contributed to the greater observed losses in coastal wetlands relative to earlier periods. Five years after Hurricane Sandy, wetland area had not significantly recovered, but more time may be necessary to assess if the observed wetland losses will persist or if new growth within flooded marsh areas will be sufficient for the wetlands to recover to pre-storm extents. Comparisons of long-term and storm-driven wetland changes can lead to improved accuracy of habitat vulnerability models and greater understanding of potential impacts of future storms and SLR to coastal wetlands.

Wetlands Ecology and Management↗

USGS2018

Inland waters

1. The total flux of carbon—which includes gaseous emissions, lateral flux, and burial—from inland waters across the conterminous United States (CONUS) and Alaska is 193 teragrams of carbon (Tg C) per year. The dominant pathway for carbon movement out of inland waters is the emission of carbon dioxide gas across water surfaces of streams, rivers, and lakes (110.1 Tg C per year), a flux not identified in the First State of the Carbon Cycle Report (SOCCR1; CCSP 2007). Second to gaseous emissions are the lateral fluxes of carbon through rivers to coastal environments (59.8 Tg C per year). Total carbon burial in lakes and reservoirs represents the smallest flux for CONUS and Alaska (22.5 Tg C per year) (medium confidence). 2. Based on estimates presented herein, the carbon flux from inland waters is now understood to be four times larger than estimates presented in SOCCR1. The total flux of carbon from inland waters across North America is estimated to be 507 Tg C per year based on a modeling approach that integrates high-resolution U.S. data and continental-scale estimates of water area, discharge, and carbon emissions. This estimate represents a weighted average of 24 grams of carbon per m2 per year of continental area exported and removed through inland waters in North America (low confidence). 3. Future research can address critical knowledge gaps and uncertainties related to inland water carbon fluxes. This chapter, for example, does not include methane emissions, which cannot be calculated as precisely as other carbon fluxes because of significant data gaps. Key to reducing uncertainties in estimated carbon fluxes is increased temporal resolution of carbon concentration and discharge sampling to provide better representations of storms and other extreme events for estimates of total inland water carbon fluxes. Improved spatial resolution of sampling also could potentially highlight anthropogenic influences on the quantity and quality of carbon fluxes in inland waters and provide information for land-use planning and management of water resources. Finally, uncertainties could likely be reduced if the community of scientists working in inland waters establishes and adopts standard measurement techniques and protocols similar to those maintained through collaborative efforts of the International Ocean Carbon Coordination Project and relevant governmental agencies from participating nations.

Book chapter↗

USGS2015

Spatial and temporal variation in marine birds in the north Gulf of Alaska: The value of marine bird monitoring within Gulf Watch Alaska

Birds offer useful insights into marine ecosystems. Marine birds are responsive to spatial and temporal variation in the environment, that often originates with fluctuations in oceanographic and climatic drivers and permeates up through food webs to conspicuous top predators such as seabirds (Coyle and Pinchuk 2005, Speckman et al. 2005, Gonzales-Solis et al. 2009, Cushing et al., this report). In that way, marine birds are excellent assimilators, samplers, and indicators of the status of marine environments (Montevecchi 1993, Piatt et al. 2007b, Zador et al. 2013). Marine bird responses to dynamic marine ecosystems can be detected in a variety of metrics, including abundance, distribution, and productivity. For example, in the northern Gulf of Alaska (GOA), decadal-scale variation in oceanographic conditions has been associated with dramatic shifts in prey composition and abundance (Anderson and Piatt 1999). In turn, these shifts were more closely correlated with changes in abundance of fish-eating birds of Prince William Sound (PWS), such as pigeon guillemots (Golet et al. 2002) and marbled and Kittlitz’s murrelets (Kuletz et al. 2011a, 2011b), than in the abundance of species that primarily consume plankton or benthic prey (Agler et al. 1999, Cushing et al., this report). Birds also are responsive to anthropogenic influences in marine environments, including commercial fishing, contamination, introduction of non-native species, coastal development, offshore resource extraction, and vessel traffic. A major anthropogenic perturbation in the northern GOA was the 1989 Exxon Valdez oil spill, in which marine birds suffered high immediate mortality (Piatt and Ford 1996). Additionally, several species showed long-term evidence of declines in the oiled areas of PWS (Lance et al. 2001), as well as impacts to reproductive success years later (Golet et al. 2002). However, the degree of direct impact and vulnerability to chronic injury, which was related to exposure to lingering oil, varied widely among species (see Esler et al., this report). Research and monitoring directed at documenting the timelines and mechanisms of wildlife recovery following the Exxon Valdez oil spill led to an unprecedented understanding of oil spill effects on marine birds, as well as previously unknown information about marine bird ecology in the northern GOA. Quantifying effects of anthropogenic influences requires an understanding of variation in marine bird abundance, distribution, and productivity, in relation to naturally occurring dynamics in marine environments continued marine bird work as part of Gulf Watch Alaska will facilitate this. In addition to their value as indicators of marine conditions and anthropogenic influences, marine birds are protected under the Migratory Bird Treaty Act and are managed by the U.S. Fish and Wildlife Service (USFWS). Marine birds have high societal value from a wide variety of interests (e.g., tourism, bird watching, hunting, mythology), and are an important source of subsistence foods in Alaska (Naves and Braem 2014). Because of the conservation interest in marine birds, as well as their value for indicating the status of marine ecosystems, monitoring of marine birds is an important component of many ocean monitoring programs, including Gulf Watch Alaska.

Alaska↗

USGS2007

New Jersey Tide Telemetry System

Each summer the population of the barrier-island communities of New Jersey increases by tens of thousands. When a coastal storm threatens these communities, the limited number of bridges and causeways that connect the islands with the mainland become overcrowded, making evacuations from the barrier islands to the mainland difficult. Timely evacuation depends on well-defined emergency evacuation plans used in conjunction with accurate flood forecasting and up to the minute (real-time) tide-level information. The 'Great Nor'easter' storm that struck the coastal areas of New Jersey on December 11, 1992, caused about $270 million in insured damages to public and private property (Dorr and others, 1995). Most of the damage was due to tidal flooding and storm surge, which were especially severe along the back bay areas. Comprehensive and reliable tide-level and meteorological data for the back bays was needed to make accurate flood forecasts. Collection of tidal data for the ocean and large bays was adequately covered by the National Oceanic and Atmospheric Administration's National Ocean Service (NOAA's NOS), but in New Jersey little to no data are available for the back-bay areas. The back bays behave quite differently than the ocean as a result of the complex interaction between the winds and the geometry of the inlets and bays. A slow moving Nor'easter can keep tide levels in back bays several feet higher than the ocean tide by not allowing tides to recede, resulting in flooding of bridges and causeways that link the barrier islands to the mainland. The U.S. Geological Survey (USGS), in cooperation with the New Jersey Department of Transportation (NJDOT), designed and installed the New Jersey Tide Telemetry System (NJTTS) with assistance from NOAA's NOS in 1997. This system is part of a statewide network of tide gages, weather stations, and stream gages that collect data in real time. The NJTTS supplies comprehensive, reliable real-time tide-level and meteorological data for flood-prone areas along the New Jersey shore and back bays. These data are transmitted to computer base stations located at offices of the National Weather Service, New Jersey State Police (NJSP), NJDOT, county emergency management agencies, other critical decision-making centers, and the World Wide Web (WWW). This fact sheet describes the NJTTS and identifies its benefits.

Fact Sheet↗

USGS2018

Does what go up also come down? Using a recruitment model to balance alewife nutrient import and export

Migrating adult Alewives Alosa pseudoharengus are a source of marine-derived nutrients on the East Coast of North America, importing nitrogen and phosphorus into freshwater habitats. Juvenile migrants subsequently transport freshwater-derived nutrients into the ocean. We developed a deterministic model to explore the theoretical nutrient dynamics of Alewife migrations at differing spawner abundances. Net nutrient balance was calculated relative to these abundances along the spawner–recruit curve. The ecological consequences of these subsidies in a particular watershed depend on the magnitude of adult escapement relative to the habitat’s carrying capacity for juveniles. At low escapement levels and assuming complete habitat access, the number of recruits produced per spawner was high and juvenile nutrient export dominated. At high escapement levels, fewer recruits were produced per spawner because recruitment is density dependent. As a result, adult nutrient import dominated. At varying levels of freshwater productivity and fisheries mortality for upstream spawners, this trend remained the same while the magnitude of the endpoints changed. Productivity level was the major determinant of export, while fisheries mortality had the strongest effect on adult import. The dynamics of this nutrient trade-off are important for managers to consider as a recovering population will likely shift from net export to net import as escapement increases. This transition will be sensitive to both harvest rates and to fish passage efficacy at dams and other barriers.

Marine and Coastal Fisheries: Dynamics, Management↗

USGS2016

Evaluation of reproductive status in Atlantic Tripletail by traditional and nonlethal approaches

Reproductive biology information is an important tool for fishery management actions such as the identification of spawning areas and the development of protective size limits, bag limits, and seasons. Such information for the management of Atlantic Tripletail Lobotes surinamensis is currently limited, particularly in the western Atlantic Ocean, as information regarding the reproductive biology of this species is sparse in the published literature. To this end, we determined the reproductive status of tripletail and compared the results of a nonlethal sampling method, plasma vitellogenin (VTG) analysis, with those of two traditional (lethal) methods, gonadosomatic index (GSI) and gonad histology. A total of 223 (122 male and 101 female) tripletail were sampled over 2 years near Jekyll Island, Georgia. Gonad histology indicated that 107 (94%) of the male tripletail were in the spawning-capable reproductive phase. Female tripletail were found in all reproductive phases, but only nine (8.9%) were in the spawning-capable phase. Plasma VTG was strongly related to GSI in females ( R 2 = 0.832, n = 77), and female GSI differed significantly among reproductive phases ( p < 0.0001). The estimated length at which 50% (L50) of female tripletail reached maturity was 463 mm; however, the L50 for male tripletail could not be determined because of the lack of immature fish within the study sample. Our study provides valuable information for the management of tripletail and indicates that a nonlethal approach (plasma VTG) may be useful for differentiating developing and spawning-capable females from males and from females in other reproductive phases.

Georgia↗

USGS2016

Potential effects of alterations to the hydrologic system on the distribution of salinity in the Biscayne aquifer in Broward County, Florida

To address concerns about the effects of water-resource management practices and rising sea level on saltwater intrusion, the U.S. Geological Survey in cooperation with the Broward County Environmental Planning and Community Resilience Division, initiated a study to examine causes of saltwater intrusion and predict the effects of future alterations to the hydrologic system on salinity distribution in eastern Broward County, Florida. A three-dimensional, variable-density solute-transport model was calibrated to conditions from 1970 to 2012, the period for which data are most complete and reliable, and was used to simulate historical conditions from 1950 to 2012. These types of models are typically difficult to calibrate by matching to observed groundwater salinities because of spatial variability in aquifer properties that are unknown, and natural and anthropogenic processes that are complex and unknown; therefore, the primary goal was to reproduce major trends and locally generalized distributions of salinity in the Biscayne aquifer. The methods used in this study are relatively new, and results will provide transferable techniques for protecting groundwater resources and maximizing groundwater availability in coastal areas. The model was used to (1) evaluate the sensitivity of the salinity distribution in groundwater to sea-level rise and groundwater pumping, and (2) simulate the potential effects of increases in pumping, variable rates of sea-level rise, movement of a salinity control structure, and use of drainage recharge wells on the future distribution of salinity in the aquifer. Results from the simulation of historical conditions indicate that the model generally represents the observed greater westward extent of elevated salinity in the central part of the intruded area relative to the northern and southernmost parts of the intruded area. Results of sensitivity testing indicate that the extent of elevated salinity is most sensitive to pumping in areas where the source of saltwater is largely offshore, from the Atlantic Ocean, and is most sensitive to sea-level rise in areas where the source of salinity is downward leakage of brackish water from canals. Simulations of future scenarios indicate that increases in pumping near the existing interface may cause the interface to advance and decreases in pumping may cause it to retreat. Climatic effects, such as periods of prolonged drought or high precipitation, may augment or counteract long-term effects of changes in pumping on aquifer salinity at well fields. With increasing rates of sea-level rise, the freshwater-saltwater interface advances progressively inland, and flow-averaged salinities at well fields near the existing interface increase commensurately. Hypothetical southeastward (downstream) re-positioning of the existing G–54 salinity-control structure may prevent the interface from moving northwestward along and near the North New River canal, but beneficial effects are localized. Implementation of freshwater recharge wells in the city of Hallandale Beach may also have only a localized freshening effect in the aquifer and little appreciable effect on the freshwater-saltwater interface or on concentrations of salinity at well fields. Model accuracy and use are limited by uncertainty in the physical properties and boundary conditions of the system, uncertainty in historical and future conditions, and generalizations made in the mathematical relationships used to describe the physical processes of groundwater flow and transport. Because of these limitations, model results should be considered in relative rather than absolute terms. Nonetheless, model results do provide useful information on the relative scale of response of the system to changes in pumping distribution, sea-level rise, and mitigation activities.

Florida↗

USGS2010

Relation of carbon 14 concentrations to saline water contamination of coastal aquifers

Naturally occurring stable or radioactive isotopes may be used in some places to identify the origin of saline water that contaminates some coastal aquifers. In a recent study to determine the origin of saline water in the Ocala Limestone aquifer near Brunswick, Georgia, the following sources were analyzed for C 14 and deuterium concentrations: potable water from the Ocala Limestone, contaminated water from the Ocala Limestone, saune water from the underlying Claiborne Group, and nearby ocean water. The chloride concentration of the groundwater ranges from about 25 ppm in the potable water to more than 2000 ppm in the deeper part of the Claiborne Group. From an interpretation of piezometric maps and other hydrologic data, previous investigators had concluded that the source of the contaminating water was the Claiborne Group and not the nearby ocean. The essentially uniform range of low values of −965 to −987‰ of the modern standard (National Bureau Standard C 14 oxalic acid) for the C 14 activity of the groundwater samples (regardless of the degree of contamination) is in agreement with this conclusion. If recent ocean water, which had a C 14 value of +285‰, were the source of contamination, the contaminated water would have had a C 14 activity higher than the activity of the fresh water. Deuterium analyses are not inconsistent with the interpretation that water from the Claiborne Group, rather than recent ocean water, is the source of the contaminating water. The concurrence of the hydrologic and the isotopic data in this area where the hydrology is well known suggests that isotopic analysis may be used to identify the origin of water in different portions of a hydrologic environment.

Georgia↗