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USGS1999

The ecological condition of estuaries in the Gulf of Mexico

The Gulf of Mexico is a vast natural resource encompassing the coastal areas of western Florida, Alabama, Mississippi, Louisiana, and Texas, as well as a portion of Mexico. Many estuaries flow into the Gulf of Mexico and serve as nursery grounds for fish, habitat for a wide variety of wildlife, shipping routes, and a source of recreation. Estuarine-dependent species constitute more than 95 percent of the commercial fishery harvests from the Gulf of Mexico, and many important recreational fishery species depend on estuaries during some part of their life cycle. Gulf estuaries are diverse and productive ecosystems that provide a variety of valuable resources, including fish and shellfish, recreation, transportation, and water supply. Assessing the overall condition of Gulf of Mexico estuaries required incorporating data from other federal, state, and local monitoring programs to augment the information on ecological indicators collected by the U.S. Environmental Protection Agency’s (USEPA) Environmental Monitoring and Assessment Program (EMAP). The resulting document would provide a synthesis of the available knowledge about the condition of Gulf of Mexico estuaries. This document is intended for use by scientists and other citizens concerned with the ecological condition of estuaries, as well as by managers and lawmakers interested in the sustained use of estuaries for commercial and recreational purposes. It also addresses public concerns about the aesthetic quality of coastal areas vital to tourism and recreation. By producing this report on the ecological condition of estuaries in the Gulf of Mexico, we have taken one step in assessing the health of this environmental resource. We have produced an environmental “report card” to be used as a guide in the evaluation of management decisions and research directions. This report is organized in three parts: (1) an introduction that gives background information on the Gulf of Mexico, estuarine ecology, and the factors that impact estuaries in the gulf, (2) the main section on priority ecological indicators used to measure the condition of estuaries in the gulf and (3) an ecological report card that summarizes the data on ecological indicators and provides a rating of the condition of estuaries in each gulf state and for gulf estuaries overall. Many of the ratings were based on the percent area of estuaries in each state exhibiting degraded or adverse levels of an indicator. Eutrophication, a condition of high nutrients often resulting in low oxygen levels and other adverse effects, is an important water quality concern for estuaries along the gulf coast. The National Oceanic and Atmospheric Administration (NOAA) has compared the Gulf of Mexico to other coastal regions like the middle Atlantic and has ranked the Gulf of Mexico as having the highest number of point sources of nutrients and the highest percentage of land use devoted to agriculture. We evaluated monitoring data for nitrogen, chlorophyll, and dissolved oxygen as indicators of eutrophication. Although most of the estuaries exhibited high nitrogen or chlorophyll or low dissolved oxygen concentrations at least once during a survey, many times these conditions were observed in small rivers or bayous rather than in the entire estuary. Often, the percent area affected was low. The gulf estuaries had moderate conditions overall for nutrients and dissolved oxygen. Definite nutrient problems were observed in >25% of the estuarine area in Louisiana and Texas and definite dissolved oxygen problems were observed in Alabama. Contaminants in estuarine sediments provide evidence of the accumulation of chemicals from anthropogenic sources. We compared the concentrations of sediment contaminants to established guideline values to determine the proportion of estuarine area that could have potential adverse effects on living organisms. Although detectable levels of contaminants were measured in almost every estuary in the Gulf of Mexico, <25% of the estuarine area in all states had contaminant concentrations that exceeded these guidelines. Wetlands are integral parts of estuarine systems. Declining acreage means habitat loss that may be the result of commercial and residential development, hydrologic alterations, or dredge and fill operations. The Gulf of Mexico region contains more than 50% of the coastal wetland acreage in the U.S. and yet it also has the highest rate of coastal wetland loss. Nine of the top ten estuarine drainage areas ranked by total wetland area are in the Gulf of Mexico region. The most current estimates of total wetland loss over the past 200 years range from 41% to 54% for the gulf states. Although coastal wetlands continue to be altered or destroyed, some estimates indicate that the rate of loss has slowed. All gulf states were rated as having severe problems with wetland loss. The condition of benthic (bottom-dwelling) invertebrates, fish and shellfish, birds, and threatened and endangered species was used to evaluate the health of estuarine fauna. Degraded benthic communities inhabited <25% of the estuarine area in all gulf states except for Texas. Commercial fish and shellfish landings may be used as an indicator of population stability while fish biomarkers are used to measure the health of individuals in the population. Commercial landings of the top four fisheries (shrimp, menhaden, blue crab, and oyster) are stable in the gulf states while fish biomarkers indicate fair to poor fish health in Alabama and Texas and good fish health elsewhere. Coastal and marine bird populations appear to be in good condition throughout the gulf. Four threatened or endangered species inhabit coastal areas in the Gulf of Mexico: brown pelican, Gulf sturgeon, manatee, and Kemp’s ridley sea turtle. In general, populations of these species are in good to fair condition in the gulf states. Public health indicators include shellfish bed closures and chemicals found in edible fish tissue. Harvest of shellfish (primarily oyster in the Gulf of Mexico) is restricted or prohibited when concentrations of bacteria or other pathogens reach levels that could impair human health. The gulf states contain the most acreage of shellfish-growing waters in the U.S. but also have the most acreage restricted for harvest. All gulf states except Mississippi have >25% of their shellfish-growing waters restricted for harvest, mostly due to pollution from wastewater treatment plants or other upstream sources. Advisories may be issued that limit consumption when the concentrations of chemicals in fish tissue exceed levels known to be harmful to humans. Although seafood consumption advisories have been issued in all gulf states, the percent of the fish population with high concentrations of contaminants is relatively low in the gulf overall.

Alabama, Florida, Louisiana, Mississippi, Texas↗

USGS2025

Estimated average annualized tsunami losses for the United States

Tsunami hazards are substantial threats to coastal communities across the United States (U.S.) and its territories. U.S. states and territories collaborate through the National Tsunami Hazard Mitigation Program (NTHMP) to develop their own tsunami-hazard information for outreach and evacuation planning. An effort to curate this tsunami-hazard information to support comprehensive risk analysis at the national level has not yet been completed. In support of this effort, the Federal Emergency Management Agency (FEMA) collaborated with the NTHMP, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Geological Survey (USGS) starting in 2023. This collaboration included the collection and analysis of existing tsunami hazard data and methods in the U.S. Tsunami subject matter experts identified and selected scientifically defensible methods for estimating the risks to buildings and populations in coastal communities. These efforts may support decision making regarding resilience policies, priorities, strategies and funding levels. Tsunamis can be triggered by earthquakes, subaerial or submarine landslides, volcanic eruptions, glacial calving, near-earth objects, weather or other events. These events can cause severe destruction, injuries, and loss of life due to powerful currents and flooding. Tsunamis pose a substantial threat to the western United States and all U.S. territories, as described below. ■ Hawaii is threatened by distant tsunamis due to its central location in the Pacific Ocean basin and has a history of local events. ■ Alaska, particularly the Aleutian Islands, faces local tsunami threats due to proximity to the Alaska-Aleutian Subduction Zone, as well as distant tsunamis from around the Pacific Ocean basin. ■ The western coast of the U.S. is threatened by distant tsunamis from around the Pacific Ocean basin and local source tsunamis from earthquakes generated within the Cascadia Subduction Zone in the Pacific Northwest. ■ American Samoa faces local tsunami threats from earthquakes generated in the nearby Tonga Trench, as well as distant tsunami threats. ■ Guam and the Commonwealth of the Northern Mariana Islands are threatened by local tsunamis from the nearby Mariana Subduction Zone, as well as distant sources from around the Pacific Ocean Basin. ■ Puerto Rico and the United States Virgin Islands are threatened by multiple local and distant tsunami sources, such as the Puerto Rico Trench (PRT), given their location in the complex seismic region of the Caribbean Sea. Several historical events stand out because of their catastrophic impacts. ■ In the Pacific Northwest, the 1700 Cascadia earthquake caused a tsunami that affected coastal Native American communities, though the extent of the damage is not fully documented (Ludwin, et al., 2005). ■ In Puerto Rico, the 1918 earthquake triggered a tsunami that caused $77 million in damage in 2022 dollars and 116 fatalities, primarily along the western coast (Coffman et al., 1982). ■ The 1946 Aleutian Islands earthquake triggered a massive tsunami that devastated Hilo, Hawaii, killing 158 people and resulting in approximately $375 million in damage (adjusted to 2022 dollars) (Fisher et al., 2023). ■ The 1964 Alaska earthquake (M 9.2) generated tsunamis that caused severe destruction in some communities across Alaska, Oregon, and California. This disaster led to a total of 124 fatalities and approximately $2.9 billion in property damage (adjusted to 2022 dollars) (Brocher et al., 2014) (Alaska Science Center, 2024). ■ In American Samoa, a tsunami generated by the 2009 Samoa earthquake (Mw 8.1) caused widespread devastation, resulting in 34 confirmed fatalities (Apatu et al., 2013) and economic losses exceeding $160 million (adjusted to 2022 dollars) (DHS, 2011). More recent events, including the 2010 Chile earthquake, the 2011 Japan earthquake, and the 2022 Tonga volcanic eruption, resulted in millions of dollars in damage to numerous ports and harbors in the U.S. South Pacific territories, Hawaii, and along the west coast of the U.S. (Lynett, et al., 2022) (Wilson, et al., 2013). Since these events, the expansion of the built environment in lowlying areas along the coast has increased the exposure of buildings and people, thereby further escalating community risk from tsunamis. This report provides a comprehensive national assessment of earthquake-generated tsunami risk. It does not include impacts from tsunamis generated by landslides, volcanic eruptions, glacial calving, near-earth objects, weather, or other events. This study is based on the best available hazard data from the U.S. Pacific Coast (California, Oregon and Washington), Alaska, Hawaii, U.S. Pacific Territories (American Samoa, Guam and Commonwealth of the Northern Mariana Islands) and Caribbean Territories (Puerto Rico and United States Virgin Islands). Tsunami risks associated with states along the East Coast, Gulf Coast, and Great Lakes are not included in this study because Hazus 6.1 software (FEMA 2024a) does not currently include the ability to analyze tsunami risk in those states. Once modeling capabilities and tsunami hazard data become available for additional states, FEMA may incorporate these data into future editions of this study.

Alaska, California, Hawaii Oregon, Washington↗

USGS2017

Rare earth element behavior during groundwater – seawater mixing along the Kona Coast of Hawaii

Groundwater and seawater samples were collected from nearshore wells and offshore along the Kona Coast of the Big Island of Hawaii to investigate rare earth element (REE) behavior in local subterranean estuaries. Previous investigations showed that submarine groundwater discharge (SGD) is the predominant flux of terrestrial waters to the coastal ocean along the arid Kona Coast of Hawaii. Groundwater and seawater samples were filtered through 0.45 μm and 0.02 μm pore-size filters to evaluate the importance of colloidal and soluble (i.e., truly dissolved ionic species and/or low molecular weight [LMW] colloids) fractions of the REEs in the local subterranean estuaries. Mixing experiments using groundwater collected immediately down gradient from a wastewater treatment facility (WWTF) proximal to the Kaloko-Hanokohau National Historic Park, and more “pristine” groundwater from a well constructed in a lava tube at Kiholo Bay, were mixed with local seawater to study the effect of solution composition (i.e., pH, salinity) on the concentrations and fractionation behavior of the REEs as groundwater mixes with seawater in Kona Coast subterranean estuaries. The mixed waters were also filtered through 0.45 or 0.02 μm filters to ascertain the behavior of colloidal and soluble fractions of the REEs across the salinity gradient in each mixing experiment. Concentrations of the REEs were statistically identical (two-tailed Student t -test, 95% confidence) between the sequentially filtered sample aliquots, indicating that the REEs occur as dissolved ionic species and/or LMW colloids in Kona Coast groundwaters. The mixing experiments revealed that the REEs are released to solution from suspended particles or colloids when Kona Coast groundwater waters mix with local seawater. The order of release that accompanies increasing pH and salinity follows light REE (LREE) > middle REE (MREE) > heavy REE (HREE). Release of REEs in the mixing experiments is driven by decreases in the free metal ion activity in solution and the concomitant increase in the amount of each REE that occurs in solution as dicarbonato complexes [i.e., Ln(CO 3 ) 2 - ] as pH increases across the salinity gradient. Input-normalized REE patterns of Kona Coast groundwater and coastal seawater are nearly identical and relatively flat compared to North Pacific seawater, indicating that SGD is the chief source of these trace elements to the ocean along the Kona Coast. Additionally, REE concentrations of the coastal seawater are between 10 and 50 times higher than previously reported open-ocean seawater values from the North Pacific, further demonstrating the importance of SGD fluxes of REEs to these coastal waters. Taken together, these observations indicate that large-scale removal of REEs, which characterizes the behavior of REEs in the low salinity reaches of many surface estuaries, is not a feature of the subterranean estuary along the Kona Coast. A large positive gadolinium (Gd) anomaly characterizes groundwater from the vicinity of the WWTF. The positive Gd anomaly can be traced to the coastal ocean, providing further evidence of the impact of SGD on the coastal waters. Estimates of the SGD fluxes of the REEs to the coastal ocean along the Kona Coast (i.e., 1.3 – 2.6 mmol Nd day -1 ) are similar to recent estimates of SGD fluxes of REEs along Florida’s east coast and to Rhode Island Sound, all of which points to the importance of SGD as significant flux of REEs to the coastal ocean.

Hawaii↗

USGS1972

Reconnaissance engineering geology of the Skagway area, Alaska, with emphasis on evaluation of earthquake and other geologic hazards

A program to study the engineering geology of most of the larger Alaska coastal communities and to evaluate their earthquake and other geologic hazards was started promptly after the 1964 Alaska earthquake; this report is a product of that program. Field-study methods were largely reconnaissance, and thus the interpretations in the report are subject to revision as further information becomes available. The report provides broad guidelines for planners and engineers when considering geologic factors during preparation of land-use plans. The use of this information should lead to minimizing future loss of life and property, especially during major earthquakes. Skagway was established in 1897 as a seaport near the head of Taiya Inlet fiord in the northern part of southeastern Alaska. Rugged mountains, steep-walled valleys, fiords, and numerous glaciers and icefields characterize the landscape of the area. Valley floors are narrow and most carry large streams, which end in tidewater deltas. Skagway is situated on the delta and lower valley floor of the Skagway River. Glaciers became vastly enlarged during the Pleistocene Epoch and presumably covered the area at least several times. The last major deglaciation probably occurred about 10,000 years ago. Subsequently, there was minor expansion and then partial retreat of glaciers; land rebound because of glacial melting is still going on today. Bedrock is composed predominantly of plutonic intrusive rocks, chiefly quartz diorite and granodiorite, some metamorphic rocks and a few dikes are present. Most bedrock is of Jurassic and Cretaceous age. An assortment of surficial deposits of Quaternary age form the valley bottoms and locally part of the valley walls. Thick deposits of sand and gravel have accumulated as deltas at the heads of fiords and as alluvium in the main stream valleys; deposits may be as much as S8S feet thick at Skagway. Locally, thin deposits mantle some of the steep bedrock slopes and also form some moderately to gently sloping ground. Manmade fill covers much of the top of the delta and floor of the Skagway valley. The fill is composed chiefly of gravel and sand. Quarried blocks of granodiorite are used as riprap to face river dikes and on fill areas exposed to waves of Taiya Inlet. The geologic structure of the area is imperfectly known. However, it appears that plutonic rocks intruded metamorphic rocks in Jurassic and Cretaceous time. Extensive faulting is strongly indicated by the strikingly linear or curvilinear pattern of fiords and many large and small valleys, but no major faults have been positively identified because of concealment by water or surficial deposits. Inferred faults include those coincident with the lower Skagway valley, Taiya Inlet-Taiya valley, and the Katzehin River delta-Upper Dewey Lake. Principal fault movements probably occurred in middle Tertiary time but some movement might have been in late Tertiary or possibly early Quaternary time. Local faults appear to join the Chilkat River fault, a segment of the important Denali fault system, one of the major tectonic elements of southeastern Alaska. One fault segment of this system shows evidence of movement within the last several hundred years. Southeastern Alaska's other major fault system is the active Fairweather-Queen Charlotte Islands fault system'near the coast of the Pacific Ocean. This fault system passes to within about 100 miles of Skagway. At its northwest end the fault system merges with the Chugach-St. Elias fault. One hundred twenty-two earthquakes, some of them strong, have been felt or possibly felt at Skagway during the years 1898 through 1969. The closest large earthquake (magnitude about 8) causing some damage at Skagway occurred July 10, 1958. Its epicenter was about 100 miles to the southwest. Other earthquakes, as much as 150 miles away, also have caused slight to moderate damage. The closest instrumentally recorded earthquake (magnitude 6) had its epicenter about 30 miles to the west of Skagway. Most earthquakes in southeastern Alaska have occurred southwest, west, or northwest of Skagway, near the coast of the Pacific Ocean. They appear to be related to movement along the Fairweather-Queen Charlotte Islands fault system or the Chugach-St. Elias fault. Most have had their epicenters offshore. Some earthquakes may be related to movement at depth along the Denali fault system. The probability of destructive earthquakes at Skagway is unknown because the tectonics of the region have not been studied in detail. However, on the basis of the seismic record and limited tectonic evidence, we suggest that sometime in the future an earthquake of at least magnitude 6 probably will occur very close to the city, a magnitude 7 earthquake might occur in the general area, and an earthquake of magnitude 8 probably will occur at some distance to the southwest, west, or northwest. Effects from nearby large earthquakes could cause extensive damage at Skagway. Nine principal effects are considered. 1. Surface displacement. Displacement of ground caused by fault movement would affect only structures built athwart the fault. However, a sudden tectonic uplift of land of as much as a few feet might affect a wide area and necessitate extensive dredging and wharf rebuilding. On the other hand, a subsidence of several feet would allow tidewater to reach inland and flood part of the harbor facilities and the business district. 2. Ground shaking. Because intensity of ground shaking during earthquakes largely depends on type and water content of the geologic material being shaken, the geologic materials are separated into three categories. Those considered susceptible to strongest shaking are grouped into category 1 (containing materials that are saturated, loose, and of medium- to fine-grain sizes); those of intermediate susceptibility in category 2; and those least susceptible to shaking in category 3. 3. Compaction of some medium-grained sediments during strong earthquake shaking could cause local settling of alluvial and deltaic surfaces. Also, some manmade fills near the harbor might undergo marked differential settling. 4. Liquefaction of saturated beds of uniform, fine sand commonly occurs during strong earthquakes. Few such beds, however, are positively identified at Skagway; some may occur within deltaic and alluvial deposits. If present, these beds might liquefy and cause local settling or trigger landslides. 5. Ejection of water-sediment mixtures from earthquake-induced fractures or from point sources, plus some associated ground subsidence, is common during major earthquakes where saturated sand and fine gravel deposits are confined beneath generally impermeable beds. Some alluvial and deltaic deposits at Skagway probably are susceptible to these processes. Locally, ejecta might cover roads and areas between buildings and fill low-lying areas. Associated ground fracturing might damage roadways, foundations of buildings, and other facilities. 6. Subaerial and subaqueous slides occur frequently during earthquakes. Saturated loose sediments on steep slopes are especially susceptible to sliding. During a major earthquake, surficial deposits forming such slopes along the southeast side of the Skagway valley probably would be subject to sliding or earthflowing on an extensive scale. Some sliding might extend onto the valley floor and damage or destroy buildings and part of the railroad. Rockfalls would be numerous and locally very large rockslides might occur. Subaqueous sliding of the Skagway delta is potentially the most damaging of earthquake effects. Sliding may have occurred there during the earthquake of September 16, 1899; any future major earthquake close to the city would cause extensive sliding, possibly triggered in part by liquefaction. If shaking continued for several minutes, successive slides might progressively remove large portions of the delta and allow extensive land spreading and fracturing of Skagway River alluvium as much as several thousand feet landward from the shoreline. 7. Glacier surfaces commonly receive extensive snow avalanches and rockslides during seismic shaking. In the Skagway area, glaciers may be disrupted at their margins, and resulting blocked streams might form lakes in a few places. If these lakes drained suddenly, downstream areas would he flooded. No long-term effects, such as glacier expansion, are expected. 8. Ground- and surface-water levels often are affected during and after strong earthquake shaking. At Skagway, ground-water levels probably would be lowered, but there would be no permanent change in water quality. Earthquake-triggered landslides could dam the Skagway River; the sudden failure of the dams might cause severe flooding. 9. Waves generated by earthquakes include tsunamis, seiche waves, and waves caused by subaerial and submarine sliding and tectonic displacement of land. Damage in the Skagway area would depend on wave height, tidal stage, and warning time. Some waves triggered by subaerial and subaqueous slides have a strong possibility of reaching heights of as much as 60 feet--or possibly even higher. Tsunamis from the open ocean must travel 160 miles of fiords before reaching Skagway, which allows sufficient time for appraisal of expectable wave height and, if necessary, evacuation of the harbor area and other low-lying ground. Geologic hazards other than those hazards associated with earthquakes include nonearthquake-induced subaerial and subaqueous slides, floods, and slow uplift (rebound) of land. Landslides of moderate size are known to have occurred from time to time during heavy rains such as those of September 1967. Subaqueous slides happen intermittently during the normal growth of deltas. Submarine cables on the floor of northern Taiya Inlet presumably were broken by such slides on September 10, 1927. Flooding by the Skagway River has inundated parts of the city many times, usually during heavy rains in the fall. Two floods were reported to have been caused by the sudden draining of glacier-dammed lakes. Dikes protect the city from many smaller floods, but heightening and broadening is needed to give full protection. Slow land uplift at Skagway, because of regional glacioisostatic rebound, averages 0.059 foot per year. On this basis, the shoreline theoretically shifted seaward 500 feet and the harbor shoaled 4.4 feet between 1897 and 1972. It is recommended that future geologic study of the Skagway area include: detailed geologic mapping and collection of data on geologic materials, joints, faults, and slope stability; complete evaluation of earthquake probability and response of materials to shaking; and collection and evaluation of periodic soundings and sediment data from Skagway and Taiya deltas to assist in forecasting the stability of the delta front.

Alaska↗

USGS2013

2010 Joint United States-Canadian Program to explore the limits of the Extended Continental Shelf aboard U.S. Coast Guard Cutter Healy--Cruise HLY1002

In August and September 2010, the U.S. Geological Survey, in cooperation with Natural Resources Canada, Geological Survey of Canada, conducted bathymetric and geophysical surveys in the Beaufort Sea and eastern Arctic Ocean aboard the U.S. Coast Guard Cutter Healy. The principal objective of this mission to the high Arctic was to acquire data in support of a delineation of the outer limits of the U.S. and Canadian Extended Continental Shelf in the Arctic Ocean, in accordance with the provisions of Article 76 of the United Nations Convention on the Law of the Sea. The Healy was accompanied by the Canadian Coast Guard icebreaker Louis S. St-Laurent. The scientific parties on board the two vessels consisted principally of staff from the U.S. Geological Survey (Healy), and the Geological Survey of Canada and the Canadian Hydrographic Service (Louis). The crew also included marine-mammal observers, Native-community observers, ice observers, and biologists conducting research of opportunity in the Arctic Ocean. Despite interruptions necessitated by three medical emergencies, the joint survey proved largely successful. The Healy collected 7,201 trackline-kilometers of swath (multibeam) bathymetry (47,663 square kilometers) and CHIRP subbottom data, with accompanying marine gravity measurements, and expendable bathythermograph data. The Louis acquired 3,673 trackline-kilometers of multichannel seismic (airgun) deep-penetration reflection data along 25 continuous profiles, as well as 34 sonobuoy refraction stations and 9,500 trackline-kilometers of single-beam bathymetry. The coordinated efforts of the two vessels resulted in seismic-reflection-profile data that were of much higher quality and continuity than if the data had been acquired with a single vessel alone. The equipment-failure rate of the seismic equipment aboard the Louis was greatly reduced when the Healy led as the ice breaker. When ice conditions proved too severe to deploy the seismic system, the Louis led the Healy, resulting in much improved quality of the swath bathymetric and CHIRP subbottom data in comparison with data collected either by the Healy in the lead or the Healy working alone. During periods when the Healy was operating alone (principally when the Louis was diverted for emergency medical evacuations or ship repairs), the Healy was able to deploy a piston-core-sampler (10 meters maximum potential recovery depending on configuration). The coring operations resulted in recovery of cores at five locations ranging from 2.4 to 5.7 meters in length from water depths ranging from 1,157 to 3,700 meters. One of these cores sited on the Alaskan margin recovered the first reported occurrence of methane hydrate from the Arctic Ocean. Ancillary science objectives, including ice observations and deployment of ice-monitoring buoys and water-column sampling to measure acidification of Arctic waters were successfully conducted. The water-column sampling included using 10 full-ocean-depth, water-sampling casts with accompanying conductivity-temperature-depth measurements. Except for the data deemed proprietary, data from the cruise have been archived and are available for download at the National Geophysical Data Center and at cooperating organizations. Outreach staff and guest teachers aboard the two vessels provided near-real-time connection between the research activities and the public through online blogs, web pages, and other media.

Open-File Report↗

USGS2021

Black Scoter habitat use along the southeastern coast of the United States

While the Atlantic Coast of the United States and Canada is a major wintering area for sea ducks, knowledge about their wintering habitat use is relatively limited. Black Scoters have a broad wintering distribution and are the only open water species of sea duck that is abundant along the southeastern coast of the United States. Our study identified variables that affected Black Scoter ( Melanitta americana ) distribution and abundance in the Atlantic Ocean along the southeastern coast of the United States. We used aerial survey data from 2009 to 2012 provided by the United States Fish and Wildlife Service to identify variables that influenced Black Scoter distribution. We used indicator variable selection to evaluate relationships between Black Scoter habitat use and a variety of broad- and fine-scale oceanographic and weather variables. Average time between waves, ocean floor slope, and the interaction of bathymetry and distance to shore had the strongest association with southeastern Black Scoter distribution.

Florida, Georgia, North Carolina, South Carolina, ↗

USGS2017

Regional acidification trends in Florida shellfish estuaries: A 20+ year look at pH, oxygen, temperature, and salinity

Increasing global CO 2 and local land use changes coupled with increased nutrient pollution are threatening estuaries worldwide. Local changes of estuarine chemistry have been documented, but regional associations and trends comparing multiple estuaries latitudinally have not been evaluated. Rapid climate change has impacted the annual and decadal chemical trends in estuaries, with local ecosystem processes enhancing or mitigating the responses. Here, we compare pH, dissolved oxygen, temperature, and salinity data from 10 Florida shellfish estuaries and hundreds of shellfish bed stations. Over 80,000 measurements, spanning from 1980 to 2008, taken on Atlantic Ocean and West Florida coast showed significant regional trends of consistent pH decreases in 8 out of the 10 estuaries, with an average rate of decrease on the Gulf of Mexico side estuaries of Florida of 7.3 × 10 −4 pH units year −1 , and average decrease on the Atlantic Coast estuaries of 5.0 × 10 −4 pH units year −1 . The rates are approximately 2–3.4 times slower than observed in pH decreases associated with ocean acidification in the Atlantic and Pacific. Other significant trends observed include decreasing dissolved oxygen in 9 out of the 10 estuaries, increasing salinity in 6 out of the 10, and temperature increases in 3 out of the 10 estuaries. The data provide a synoptic regional view of Florida estuary trends which reflect the complexity of changing climate and coastal ocean acidification superimposed on local conditions. These data provide context for understanding, and interpreting the past and predicting future of regional water quality health of shellfish and other organisms of commercial and ecological significance along Florida’s coasts.

Estuaries and Coasts↗

USGS1982

Preliminary study of methods for upgrading USGS Antarctic seismological capability

The purpose of this study is to evaluate potential methods for obtaining higher quality seismic data from Antarctica. Currently, USGS-sponsored WWSSN stations are located at Scott Base, Sanae Base, and at South Pole Station. Scott and Sanae Stations are located near the coast; data obtained from coastal installations are normally degraded by noise generated by ocean wave action on the coast. Operations at South Pole are rather difficult because of the severe environmental characteristics and the extended logistics which are required to provide supplies and operating personnel to its remote location. Short-period data quality from Pole Station has been moderately high with a short-period magnification of 100K at 1Hz.

Open-File Report↗

USGS2021

Establishing the foundation for the global observing system for marine life

Maintaining healthy, productive ecosystems in the face of pervasive and accelerating human impacts including climate change requires globally coordinated and sustained observations of marine biodiversity. Global coordination is predicated on an understanding of the scope and capacity of existing monitoring programs, and the extent to which they use standardized, interoperable practices for data management. Global coordination also requires identification of gaps in spatial and ecosystem coverage, and how these gaps correspond to management priorities and information needs. We undertook such an assessment by conducting an audit and gap analysis from global databases and structured surveys of experts. Of 371 survey respondents, 203 active, long-term (>5 years) observing programs systematically sampled marine life. These programs spanned about 7% of the ocean surface area, mostly concentrated in coastal regions of the United States, Canada, Europe, and Australia. Seagrasses, mangroves, hard corals, and macroalgae were sampled in 6% of the entire global coastal zone. Two-thirds of all observing programs offered accessible data, but methods and conditions for access were highly variable. Our assessment indicates that the global observing system is largely uncoordinated which results in a failure to deliver critical information required for informed decision-making such as, status and trends, for the conservation and sustainability of marine ecosystems and provision of ecosystem services. Based on our study, we suggest four key steps that can increase the sustainability, connectivity and spatial coverage of biological Essential Ocean Variables in the global ocean: (1) sustaining existing observing programs and encouraging coordination among these; (2) continuing to strive for data strategies that follow FAIR principles (findable, accessible, interoperable, and reusable); (3) utilizing existing ocean observing platforms and enhancing support to expand observing along coasts of developing countries, in deep ocean basins, and near the poles; and (4) targeting capacity building efforts. Following these suggestions could help create a coordinated marine biodiversity observing system enabling ecological forecasting and better planning for a sustainable use of ocean resources.

Frontiers in Marine Science↗

USGS2005

Resource inventory of marine and estuarine fishes of the West Coast and Alaska: A checklist of North Pacific and Arctic Ocean species from Baja California to the Alaska - Yukon border

This is a comprehensive inventory of the fish species recorded in marine and estuarine waters between the Alaska–Yukon Territory border in the Beaufort Sea and Cabo San Lucas at the southern end of Baja California and out about 300 miles from shore. Our westernmost range includes the eastern Bering Sea and Aleutian Islands. In addition, we have also included our best impressions of the species that might reasonably be expected to be members of the West Coast ichthyofauna but have not yet been captured or reported within our study area. These species are marked with an asterisk (*) and have been reported (1) in the western Bering Sea; (2) off Canada’s Yukon Territory and adjacent portions of the Northwest Territories; (3) along the southern-eastern tip (non-Pacific side) of Baja California; and (4) in waters somewhat beyond 300 miles from shore. Although the term West Coast usually refers to the coast of the continuous western states, our usage herein means the entire study area. The West Coast inventory within this range encompasses fish fauna from 44 orders, 232 families, and a minimum of 1,450 species. Please note that introduced and invasive fish species are marked by double asterisks (**) and that their scientific names are highlighted in gray. We have compiled this document because the most geographically inclusive previous inventories (Jordan and Evermann 1896a, Jordan et al. 1930) are largely of historical interest and are out of date. More recent lists and compilations have either focused on relatively narrow taxonomic groups (e. g., Kramer et al. 1995, Love et al. 2002), are regional in scope (e. g., Hart 1973, Hubbs et al. 1979, Mecklenburg et al. 2002), or focus on commonly observed species (e. g., Miller and Lea 1972, Eschmeyer and Herald 1983). With the explosion of coastal research and environmental assessments, beginning in the 1970s, and more recently, renewed scientific interest in biodiversity (e.g., effects of global climate change), our own studies on related subjects regarding fish populations, assemblages, and biological habitats, suggested this was the appropriate time to update and summarize our knowledge.

Report↗

USGS2013

Refinement of late-Early and Middle Miocene diatom biostratigraphy for the east coast of the United States

Integrated Ocean Drilling Program (IODP) Expedition 313 continuously cored Lower to Middle Miocene sequences at three continental shelf sites off New Jersey, USA. The most seaward of these, Site M29, contains a well-preserved Early and Middle Miocene succession of planktonic diatoms that have been independently correlated with the geomagnetic polarity time scale derived in studies from the equatorial and North Pacific. Shallow water diatoms (species of Delphineis, Rhaphoneis, and Sceptroneis) dominate in onshore sequences in Maryland and Virginia, forming the basis for the East Coast Diatom Zones (ECDZ). Integrated study of both planktonic and shallow water diatoms in Hole M29A as well as in onshore sequences in Maryland (the Baltimore Gas and Electric Company well) and Delaware (the Ocean Drilling Program Bethany Beach corehole) allows the refinement of ECDZ zones into a high-resolution biochronology that can be successfully applied in both onshore and offshore regions of the East Coast of the United States. Strontium isotope stratigraphy supports the diatom biochronology, although for much of the Middle Miocene it suggests ages that are on average 0.4 m.y. older. The ECDZ zonal definitions are updated to include evolutionary events of Delphineis species, and regional occurrences of important planktonic diatom marker taxa are included. Updated taxonomy, reference to published figures, and photographic images are provided that will aid in the application of this diatom biostratigraphy.

East Coast↗

USGS2017

Overview of the U.S. Nuclear Regulatory Commission collaborative research program to assess tsunami hazard for nuclear power plants on the Atlantic and Gulf Coasts

In response to the 2004 Indian Ocean Tsunami, the United States Nuclear Regulatory Commission (US NRC) initiated a long-term research program to improve understanding of tsunami hazard levels for nuclear facilities in the United States. For this effort, the US NRC organized a collaborative research program with the United States Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA) with a goal of assessing tsunami hazard on the Atlantic and Gulf Coasts of the United States. Necessarily, the US NRC research program includes both seismic- and landslide-based tsunamigenic sources in both the near and the far fields. The inclusion of tsunamigenic landslides, an important category of sources that impact tsunami hazard levels for the Atlantic and Gulf Coasts is a key difference between this program and most other tsunami hazard assessment programs. The initial phase of this work consisted of collection, interpretation, and analysis of available offshore data, with significant effort focused on characterizing offshore near-field landslides and analyzing their tsunamigenic potential and properties. In the next phase of research, additional field investigations will be conducted in key locations of interest and additional analysis will be undertaken. Simultaneously, the MOST tsunami generation and propagation model used by NOAA will first be enhanced to include landslide-based initiation mechanisms and then will be used to investigate the impact of the tsunamigenic sources identified and characterized by the USGS. The potential for probabilistic tsunami hazard assessment will also be explore in the final phases of the program.

Conference Paper↗

USGS2010

Cenozoic plate motions and the volcano-tectonic evolution of western Oregon and Washington

A refined northeast Pacific plate-motion model provides a framework for analysis of the Tertiary volcanic and tectonic history of western Oregon and Washington. We examine three possible models for the origin of the allochthonous Paleocene and Eocene oceanic basalt basement of the Coast Range: (1) accretion to the continent of hot spot generated linear seamount chains; (2) accretion of thick oceanic crust and seamounts generated during Farallon-Kula spreading reorganizations between 61 and 48 Ma; and (3) eruption of basalt during oblique rifting of the continental margin as it overrode an active Yellowstone hot spot on the Kula-Farallon ridge. The plate model suggests that microplate rotation and accretion of hot spot generated linear aseismic ridges cannot be easily reconciled with rapid northeast motion of the KuIa and Farallon plates and the well-established paleomagnetic rotations. Following emplacement of the Coast Range basement, changes in the character of forearc, back arc and Cascade arc volcanism correlate with a marked decrease in the rate of Farallon-North America convergence between 43 and and 28 Ma. This slowdown may be responsible for (1) westward stepping of the volcanic arc front from the Challis axis to a Cascade axis at about 42 Ma; (2) a subsequent episode of increased ash flow tuff volcanism and extension in the Cascade arc between 37 and 18 Ma that correlates with the “ignimbrite flare-up” in the Basin and Range; and (3) a period of extensional basaltic and alkalic volcanism and intrusion in the Coast Range between 44 and 28 Ma. Reduction of the convergence rate and westward stepping of the flexure in the subducted slab may have reduced the horizontal compressive stress on the continent, allowing increased injection of magma into the crust, development of large, shallow magma chambers, and the outbreak of extensional volcanism over a large area behind the Farallon-North America subduction zone.

Oregon, Washington↗

USGS2009

Coastal ocean transport patterns in the central Southern California Bight

In the past decade, several large programs that monitor currents and transport patterns for periods from a few months to a few years were conducted by a consortium of university, federal, state, and municipal agencies in the central Southern California Bight, a heavily urbanized section of the coastal ocean off the west coast of the United States encompassing Santa Monica Bay, San Pedro Bay, and the Palos Verdes shelf. These programs were designed in part to determine how alongshelf and cross-shelf currents move sediments, pollutants, and suspended material through the region. Analysis of the data sets showed that the current patterns in this portion of the Bight have distinct changes in frequency and amplitude with location, in part because the topography of the shelf and upper slope varies rapidly over small spatial scales. However, because the mean, subtidal, and tidal-current patterns in any particular location were reasonably stable with time, one could determine a regional pattern for these current fields in the central Southern California Bight even though measurements at the various locations were obtained at different times. In particular, because the mean near-surface flows over the San Pedro and Palos Verdes shelves are divergent, near-surface waters from the upper slope tend to carry suspended material onto the shelf in the northwestern portion of San Pedro Bay. Water and suspended material are also carried off the shelf by the mean and subtidal flow fields in places where the orientation of the shelf break changes abruptly. The barotropic tidal currents in the central Southern California Bight flow primarily alongshore, but they have pronounced amplitude variations over relatively small changes in alongshelf location that are not totally predicted by numerical tidal models. Nonlinear internal tides and internal bores at tidal frequencies are oriented more across the shelf. They do not have a uniform transport direction, since they move fine sediment from the shelf to the slope in Santa Monica Bay, but carry suspended material from the mid-shelf to the beach in San Pedro Bay. It is clear that there are a large variety of processes that transport sediments and contaminants along and across the shelf in the central Southern California Bight. However, because these processes have a variety of frequencies and relatively small spatial scales, the dominant transport processes tend to be localized and have dissimilar characteristics even in adjacent regions of this small part of the coastal ocean. ?? 2009 The Geological Society of America.

Special Paper of the Geological Society of America↗

USGS2012

Cultured fungal associates from the deep-sea coral Lophelia pertusa

The cold-water coral Lophelia pertusa provides important habitat to many deep-sea fishes and invertebrates. Studies of the microbial taxa associated with L. pertusa thus far have focused on bacteria, neglecting the microeukaryotic members. This is the first study to culture fungi from living L. pertusa and to investigate carbon source utilization by the fungal associates. Twenty-seven fungal isolates from seven families, including both filamentous and yeast morphotypes, were cultured from healthy L. pertusa colonies collected from the northern Gulf of Mexico, the West Florida Slope, and the western Atlantic Ocean off the Florida coast. Isolates from different sites were phylogenetically closely related, indicating these genera are widely distributed in association with L. pertusa. Biolog™ Filamentous Fungi microtiter plates were employed to determine the functional capacity of a subset of isolates to grow on varied carbon sources. While four of the isolates exhibited no growth on any provided carbon source, the rest ( n =10) grew on 8.3–66.7% of carbon sources available. Carbohydrates, carboxylic acids, and amino acids were the most commonly metabolized carbon sources, with overlap between the carbon sources used and amino acids found in L. pertusa mucus. This study represents the first attempt to characterize a microeukaryotic group associated with L. pertusa. However, the functional role of fungi within the coral holobiont remains unclear.

Florida↗

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↗

USGS2001

Density structure of the lithosphere in the southwestern United States and its tectonic significance

We calculate a density model of the lithosphere of the southwestern United States through an integrated analysis of gravity, seismic refraction, drill hole, and geological data. Deviations from the average upper mantle density are as much as ?? 3%. A comparison with tomographic images of seismic velocities indicates that a substantial part (>50%) of these density variations is due to changes in composition rather than temperature. Pronounced mass deficits are found in the upper mantle under the Basin and Range Province and the northern part of the California Coast Ranges and adjacent ocean. The density structure of the northern and central/southern Sierra Nevada is remarkably different. The central/southern part is anomalous and is characterized by a relatively light crust underlain by a higher-density upper mantle that may be associated with a cold, stalled subducted plate. High densities are also determined within the uppermost mantle beneath the central Transverse Ranges and adjoining continental slope. The average density of the crystalline crust under the Great Valley and western Sierra Nevada is estimated to be up to 200 kg m~3 higher than the regional average, consistent with tectonic models for the obduction of oceanic crust and uppermost mantle in this region.

Journal of Geophysical Research B: Solid Earth↗

USGS2026

Widespread terrestrial ecosystem disruption at the onset of the Paleocene–Eocene Thermal Maximum

The Paleocene–Eocene Thermal Maximum (PETM, ~56 Mya) interval was marked by massive 13 C-depleted carbon emissions into the ocean/atmosphere system, manifested as a negative carbon isotope excursion (CIE) in sedimentary components, and ~5 °C global average warming. Episodes of hydrological perturbations and soil-erosion have been widely documented for the PETM but their link with vegetation- and carbon cycle changes remain poorly constrained. Here, we present organic microfossil evidence showing a strong increase in fern-dominated pioneer vegetation that replaced coniferous forests on the margin of the Norwegian Sea during the first millennia of the CIE. With the present stratigraphic constraints, the “fern spike” occurred simultaneously in terrestrial settings along the North Sea, Arctic Ocean, the US east coast and in southern Australia, indicating that pioneer vegetation persisted for several millennia following a partial collapse of previously stable terrestrial ecosystems. Both the ferns and influx of microcharcoal imply recurrent physical disturbance, including soil destabilization and erosion, potentially linked to droughts, wildfires, and strong hydrological forcing resulting from extreme climate change. Together with evidence for reworked clay minerals and ancient organic matter (kerogen), these findings show that highly disturbed terrestrial ecosystems were widespread across mid- and high-latitude regions globally. Carbon cycle model simulations suggest that a substantial loss of standing and buried biomass, along with oxidation of soil organic matter, acted as important positive feedbacks during the onset of the CIE. Additionally, enhanced kerogen weathering likely contributed as another major positive feedback throughout both the onset and main phase of the CIE.

Proceedings of the National Academy of Sciences↗