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At least 937 records · Page 52Linked to original sources

USGS2007

Significant findings from a water-quality study on Prairie Band Potawatomi Reservation, northeastern Kansas, June 1996 through August 2006

Water-quality samples were collected from surface- (stream-) and ground-water sites on and near the Prairie Band Potawatomi Reservation in northeastern Kansas (fig. 1) from June 1996 through August 2006 as part of a cooperative study between the U.S. Geological Survey (USGS) and the Prairie Band Potawatomi Nation (Schmidt and others, 2007). Surface- and ground-water quality were evaluated using applicable drinking-water standards to consider whether these resources can be used in the future to supply drinking water for the reservation. Presently (2007), drinking water on the reservation is purchased from Rural Water District #3 in Jackson County (Sharon Bosse, Prairie Band Potawatomi Nation Department of Planning and Environmental Protection, oral commun., 2007). Results of water-quality analyses are summarized in the following sections. Water-quality activities for this study are documented in several reports (Trombley, 1999, 2001; Schmidt, 2004; Schmidt and others, 2007).

Kansas↗

USGS1985

Hydrologic effects of ground- and surface-water withdrawals in the Milford area, Elkhart and Kosciusko counties, Indiana

Agricultural irrigation in northern Indiana has increased rapidly since 1975 and might double by the year 2000. A 16.5 square-mile area in north-central Indiana was studied to determine possible effects of increased irrigation on local water supply. In 1982, an average of 2 inches of water was used to irrigate 975 acres of sandy soil overlying highly transmissive outwash deposits. Irrigational pumpage was 75 percent of the summer water use but was less than potential irrigational pumpage because (1) only one-third of the suitable land was irrigated, and (2) precipitation was near normal for the year. A three-dimensional digital flow model, calibrated with data collected in 1982, was used to simulate four hypothetical pumping plans representing various irrigational schemes and possible rainfall conditions: (1) 1982 acreage irrigated and 1982 (above normal) precipitation; (2) 1982 acreage irrigated and below-normal precipitation; (3) maximum acreage irrigated and normal precipitation; and (4) maximum acreage irrigated and below-normal precipitation. A fifth pumping plan was used to simulate maximum year-round water use. Plan 5 was not designed to simulate irrigational development but rather a maximum rate of withdrawal sustainable year-round until steady-state is reached. Of the four pumping plans that simulated irrigational pumpage, plan 4 had the greatest effect on ground- and surface-water supply. Compared with 1982 pumpage, this plan represented a thirteenfold increase in the volume of water pumped for irrigation from wells and from Turkey Creek, a stream bordering the area of study. The model predicted a potentiometric decline of as much as 20.7 feet over an 8-acre area of the aquifer. This decline was one-fourth of the available drawdown and would not dewater the source aquifer. Streamflow in Turkey Creek would be reduced 39 percent by simulated ground-water and surface-water pumpage but remaining flow would still be twice the 7-day, 10-year low flow. However, the model predicted that flow in two smaller streams would be reduced to zero. The rate of pumping used in plan 5 was nearly 4 times the pumping rate in 1982. Potentiometric decline for plan 5 was as much as 40 percent of available drawdown, and predicted streamflow reduction would cause flow in Turkey Creek to decrease below the 7-day, 10-year low flow. Results of plans 1, 2, 3, and 4 indicate that the outwash system provides adequate water for current (1982) needs and substantial growth for irrigation. However, maximum irrigational development might cause temporary, local competition for water in several parts of the area. Plan 5 indicates .that water use could increase substantially before effects of pumping would prevail year-round.

Indiana↗

USGS2011

Water-level surface in the Chicot equivalent aquifer system in southeastern Louisiana, 2009

The Chicot equivalent aquifer system is an important source of freshwater in southeastern Louisiana. In 2005, about 47 million gallons per day (Mgal/d) were withdrawn from the Chicot equivalent aquifer system in East Baton Rouge, East Feliciana, Livingston, Tangipahoa, St. Helena, St. Tammany, Washington, and West Feliciana Parishes. Concentrated withdrawals exceeded 5 Mgal/d in Bogalusa, the city of Baton Rouge, and in northwestern East Baton Rouge Parish. In the study area, about 30,000 wells screened in the Chicot equivalent aquifer system were registered with the Louisiana Department of Transportation and Development (LaDOTD). These wells were constructed for public-supply, industry, irrigation, and domestic uses. Most of the wells were registered as domestic-use wells and are small-diameter, low-yielding wells. Total withdrawal from the Chicot equivalent aquifer system for domestic use was estimated to be 12 Mgal/d in 2005. This report documents the 2009 water-level surface of the Chicot equivalent aquifer system in southeastern Louisiana. The report also shows differences in water-level measurements for the years 1991 and 2009 at selected sites. Understanding changes and trends in water levels is important for continued use, planning, and management of groundwater resources. The U.S. Geological Survey, in cooperation with the Louisiana Department of Transportation and Development, conducted this study of the water-level surface of the Chicot equivalent aquifer system as part of an ongoing effort to monitor groundwater levels in aquifers in Louisiana.

Louisiana↗

USGS2020

Assessment of bridge scour countermeasures at selected bridges in the United States, 2014–18

Erosion of the streambed, known also as scour, around pier 3 of the New York State Thruway bridge over Schoharie Creek caused the pier to fail, which ultimately resulted in bridge failure during the flooding event of April 5, 1987. The Federal Highway Administration (FHWA) responded to the need for better guidance on the evaluation of bridge scour and the selection and installation of scour countermeasures with the release of several Hydraulic Engineering Circulars. Although this information has been available, used, and updated over the years, an evaluation of the current conditions of scour countermeasures has not been performed. Therefore, the U.S. Geological Survey, in cooperation with the FHWA, began a study in 2013 to assess the current conditions of bridge scour countermeasures at selected sites around the country. The bridge scour countermeasure site assessments included reviewing countermeasure design plans, field inspections, traditional surveys, motion-compensated terrestrial light detection and ranging technology (lidar), high-resolution multi-beam bathymetry scanning, underwater video imaging, and a review of the peak and daily streamflow history for the associated river or stream. A total of 34 bridge scour countermeasure sites were selected in 11 states for this study. The types of countermeasures installed at the bridge scour study sites ranged from riprap, the most common countermeasure in the study, to A-Jacks and cabled-concrete mattresses. The installed countermeasures were generally exposed to hydraulic forces from floods that equaled or exceeded the 1-percent, and even the 0.2-percent, annual exceedance probability at some of the study sites, but not all. The field inspections and countermeasure evaluations identified areas of shifting, slumping, and some scour holes and damage or washouts to the countermeasures, but generally most remained in place. The high-resolution laser scanner data, photo imaging and traditional survey data, and field notes were provided to the FHWA for expert evaluation of the bridge scour countermeasure performance.

Alabama, Florida, Idaho, Illinois, Indiana, Iowa, ↗

USGS1999

Preliminary geologic map of the Chugach National Forest special study area, Alaska

In 1990, both the U.S. Geological Survey and U.S. Bureau of Mines were contacted by the Chugach National Forest (CNF) for the purpose of providing mineral resource information for the CNF Master Plan during the planning period fiscal years 1991-1994. This information is to address the terms and requirements of the 1986 Settlement Agreement and to provide mineral and geologic information useful to the CNF for making land-use decisions. In early 1992 an Interagency Agreement between the U.S. Geological Survey, the U.S. Bureau of Mines and the Chugach National Forest was signed. In this agreement the U.S. Geological Survey is to provide a report which estimates the undiscovered mineral endowments of the 'special' study area and to identify the potential for mineral discovery and development. The U.S. Bureau of Mines was to prepare a report updating the discovered mineral endowment of the Special Study Area. These reports are now published (Roe and Balen, 1994; Nelson and others, 1994). This geologic map is a component of the U.S. Geological Survey contribution to the overall project.

Alaska↗

USGS2016

Evaluation of National Atmospheric Deposition Program measurements for colocated sites CO89 and CO98 at Rocky Mountain National Park, water years 2010–14

Atmospheric wet-deposition monitoring in Rocky Mountain National Park included precipitation depth and aqueous chemical measurements at colocated National Atmospheric Deposition Program/National Trends Network (NADP/NTN) sites CO89 and CO98 (Loch Vale) during water years 2010–14 (study period). The colocated sites were separated by approximately 6.5 meters horizontally and 0.5 meter in elevation, in accordance with NADP siting criteria. Assessment of the 5-year record of colocated data is intended to inform man-agement decisions pertaining to the achievement of nitrogen deposition reduction goals of the Rocky Mountain National Park Nitrogen Deposition Reduction Plan. The data at site CO98 met NADP completeness criteria for the first time in 29 years of operation in 2011 and then again in 2012. During the study period, data at site CO89 met completeness criteria in 2012. Median weekly relative precipitation-depth differences between sites CO89 and CO98 ranged from 0 to 0.25 millimeter during the study period. Median weekly absolute percent differences in sample volume ranged from 5 to 10 percent. Median relative concentration differences for weekly ammonium (NH 4 + ) and nitrate (NO 3 - ) concentrations were near the NADP Central Analytical Laboratory’s method detection limits and thus were considered small. Absolute percent differences for water-year 2010–14 precipitation-weighted mean concentrations of NH 4 + , NO 3 - , and inorganic nitrogen (N inorg ) ranged from 0.0 to 25.7 percent. Absolute percent differences for water-year 2010–14 NH 4 + , NO 3 - , and N inorg deposition ranged from 2.1 to 18.9 percent, 3.3 to 24.5 percent, and 0.3 to 17.4 percent, respectively.

Colorado↗

USGS2022

Voluntary Guidance for States to Incorporate Climate Adaptation in State Wildlife Action Plans and Other Management Plans

The Voluntary Guidance for States to Incorporate Climate Adaptation into State Wildlife Actions Plans and other Management Plans aims to help state fish and wildlife agencies incorporate climate change adaptation for fish and wildlife and their habitats into State Wildlife Action Plans (SWAPs) and other natural resource management plans. This update to the original 2009 Voluntary Guidance reflects the advancements in climate science and in our understanding and implementation of climate adaptation developed over the past 13 years. The document provides principles and tools that can be used to plan for and implement climate change adaptation, voluntary guidance for incorporating climate change into the existing required elements of SWAPs, and case studies to demonstrate adaptation strategies deployed by states in their management efforts. Climate change continues to be a significant issue for wildlife and natural systems and for the people who rely on the ecosystem services they provide. There is now a well-established and growing scientific literature on the impacts of climate change on wildlife and their habitats, including climate-driven range shifts, population changes, and even species extinctions. At the same time, efforts to address climate change impacts can be made in cooperation with efforts to address other threats, including habitat loss/fragmentation from development, introduction of invasive species, water pollution, and wildlife diseases, many of which may be exacerbated by climate change. Since climate change is a complex and often politically charged issue, it is understood that the decision to revise SWAPs, or other plans, to address climate change rests solely with each state fish and wildlife agency. All states are required to update their SWAPs by 2025 to qualify for federal funding. Although consideration of climate change is not a requirement for this revision of SWAPs, assessing the impacts of climate change and identifying species and habitats vulnerable to those impacts can help states meet the required eight elements for the revision and prepare for funding opportunities that can support climate adaptation efforts. The Inflation Reduction Act of 2022 and the Recovering America’s Wildlife Act, if passed by the Senate, would provide billions of dollars to states to implement SWAPs, including addressing climate change impacts on fish and wildlife. The Voluntary Guidance Document introduces and explains seven overarching principles for incorporating climate adaptation into SWAPs. These principles (found in Chapter 2) are: 1. Fully integrate climate change into SWAPs 2. Adopt forward-looking goals 3. Explicitly link actions to climate vulnerabilities 4. Manage for change, not just persistence 5. Consider broader landscapes and longer timeframes 6. Address uncertainty by considering future scenarios and use of adaptive management 7. Engage diverse partners with climate experience and expertise

Report↗

USGS2013

Perception, experience, and indigenous knowledge of climate change and variability: the case of Accra, a sub-Saharan African city

Several recent international assessments have concluded that climate change has the potential to reverse the modest economic gains achieved in many developing countries over the past decade. The phenomenon of climate change threatens to worsen poverty or burden populations with additional hardships, especially in poor societies with weak infrastructure and economic well-being. The importance of the perceptions, experiences, and knowledge of indigenous peoples has gained prominence in discussions of climate change and adaptation in developing countries and among international development organizations. Efforts to evaluate the role of indigenous knowledge in adaptation planning, however, have largely focused on rural people and their agricultural livelihoods. This paper presents the results of a study that examines perceptions, experiences, and indigenous knowledge relating to climate change and variability in three communities of metropolitan Accra, which is the capital of Ghana. The study design is based on a three-part conceptual framework and interview process involving risk mapping, mental models, and individual stressor cognition. Most of the residents interviewed in the three communities of urban Accra attributed climate change to the combination of deforestation and the burning of firewood and rubbish. None of the residents associated climate change with fossil fuel emissions from developed countries. Numerous potential adaptation strategies were suggested by the residents, many of which have been used effectively during past drought and flood events. Results suggest that ethnic residential clustering as well as strong community bonds in metropolitan Accra have allowed various groups and long-settled communities to engage in the sharing and transmission of knowledge of weather patterns and trends. Understanding and building upon indigenous knowledge may enhance the design, acceptance, and implementation of climate change adaptation strategies in Accra and urban regions of other developing nations.

Accra↗

USGS2020

Water balance as an indicator of natural resource condition: Case studies from Great Sand Dunes National Park and Preserve

Managing climate impacts to natural resources in protected areas can be hampered by lack of monitoring data, poor understanding of natural resource responses to climate, or lack of timely condition assessments that can inform management actions. Here we demonstrate the utility of water balance as a tool for understanding natural resource responses to climate by developing case studies focused on stream flow, vegetation production, and wildfire ignition at Great Sand Dunes National Park and Preserve (GSDNP), U.S.A. The efficacy of water balance to predict these responses stems from the explicit integration of climate with site conditions that modify the effects of climate. This in turn results in estimates of water availability, water use, and water need that are proximal drivers of aquatic and terrestrial natural resource conditions. The water balance model successfully forecasted stream flow (r 2 = 0.69, P < 0.001); determined the critical water needs for maintaining annual vegetation production in different vegetation types spanning a large environmental gradient (r 2 = 0.18–0.71); and predicted proportion of historic wildfire ignitions in forest (r 2 = 0.96–0.99) and non-forest (r 2 = 0.96–0.97) vegetation types. Collectively, these case studies demonstrate practical approaches to translate climate data into assessments of natural resource condition that inform long-term planning and near-term strategic actions needed for conservation of protected areas.

Great Sand Dunes National Park and Preserve↗

USGS2020

Influence of demand and capacity in transportation simulations of short-notice, distant-tsunami evacuations

Distant tsunamis require short-notice evacuations in coastal communities to minimize threats to life safety. Given the available time to evacuate and potential distances out of hazard zones, coastal transportation planners and emergency managers can expect large proportions of populations to evacuate using vehicles. A community-wide, short-notice, distant-tsunami evacuation is challenging because it creates a sudden, significant, and concentrated demand on road-network systems. Transportation planners and emergency managers need methods to help them determine if a road network can handle an evacuation surge and if not, where interventions can best reduce overall clearance times. We use the coastal community of Bay Farm Island (City of Alameda, California, USA) and the distant-tsunami threat posed by Aleutian-Alaskan earthquakes as a case study to explore the use of agent-based, transportation simulation to support short-notice, tsunami-evacuation planning. Results demonstrate how vehicle simulation can characterize network performance during a tsunami evacuation in the absence of real-world measurements of vehicle demand and flow. Changes in vehicle demand had the greatest influence on reductions in clearance times and recommended reductions varied based on time of day. Doubling the capacity of certain road segments based on traditional vehicle-capacity ratios and level-of-service thresholds reduced overall clearance time in some cases but increased it in other cases. The proposed simulation approach can serve as an analytical foundation for future efforts to characterize distant-tsunami evacuations in other coastal communities throughout the world.

California↗

USGS2018

Description of disparate responses of two indoor feral bee colonies

As is sometimes the case, field research does not always go according to plan. This is especially true when the research involves free-ranging animals. We recently conducted a preliminary field study that involved placing a beehive in a tent and individually releasing marked honey bees (Apis mellifera) outdoors to study their ability to locate sugar water rewards by following olfactory cues. Herein, we relay our experiences with two beehives and their disparate responses to being held in tents We believe our observations, although anecdotal, can provide much needed guidance to researchers and beekeepers who may need to temporarily hold honey bee colonies in tents or other enclosures.

Bee World↗

USGS2001

Subspecific affinity of black bears in the White River National Wildlife Refuge

The black bear population of the White River National Wildlife Refuge (NWR) is adjacent to populations of black bear in Louisiana ( Urusus americanus luteolus ) which are listed as threatened under the U.S. Endangered Species Act. Wildlife management plans can pose restrictions on bear harvests and timber extraction; therefore the management plan for the White River NWR is sensitive to subspecific classification of its bear population. The objective of this study was to analyze genetic variation in the White River NWR and seven adjacent populations of black bears to assess the subspecific affinity of the White River NWR population. Here we report the variation at seven microsatellite DNA loci among eight black bear populations. The patterns of genetic variation gave strong support for distinguishing a southern group of black bears comprised of the White River, Arkansas; Tensas River, Louisiana; Upper Atchafalaya, Louisiana; Lower Atchafalaya, Louisiana; and Alabama/Mississippi populations. Phylogenetic analysis of individual variation suggested that historical black bear introductions into Arkansas and Louisiana affected gene pools of certain southern receiving populations, but did not significantly change interpopulation relatedness. Phylogenetic inferences at both the population and individual levels support the hypothesis that the White River NWR population of black bears belongs to the U. a. luteolus subspecies.

Arkansas↗

USGS2025

Alaskan hydrology in transition: Changing precipitation and evapotranspiration patterns are projected to reshape seasonal streamflow and water temperature by midcentury (2035-2064)

High spatial and temporal resolution models are essential for understanding future climate impacts and developing effective climate resilience plans. However, existing regional and global river models often lack the resolution needed to accurately capture local conditions. This study uses a series of high-resolution models, including the Regional Arctic System Model, mizuRoute, and the river basin model, to analyze Arctic and sub-Arctic Alaskan hydrology. We compare a historical baseline (1991–2020) with six midcentury (2035–64) futures: two pseudo–global warming scenarios based on historical meteorology and four direct dynamically downscaled global climate models. The six futures reveal significant uncertainty in future annual discharge and peak flows, although a widespread increase in discharge during April (+63%) and October (+31%) is consistently shown across models. Projected increases in rain and shifting weather patterns lead to a transition from snow to rain in spring and autumn, reducing the fraction of snowmelt contributing to river discharge. Rising evapotranspiration moderates discharge changes, particularly in autumn, by offsetting precipitation increases. Average summer river temperatures are projected to increase by approximately 1.5°C, doubling the number of river segments that experience 18°C days, a critical threshold for salmon survival, and intensifying the heat flux to the ocean adding an average of 3.3 × 10 12 MJ yr −1 . These changes in the hydrologic cycle could profoundly impact riverine and oceanic ecosystems, posing substantial challenges to communities reliant on these environments.

Alaska, Yukon↗

USGS2011

Migration and spawning of radio-tagged zulega Prochilodus argenteus in a dammed Brazilian river

It is difficult for agencies to evaluate the impacts of the many planned dams on Sa??o Francisco River, Brazil, migratory fishes because fish migrations are poorly known. We conducted a study on zulega Prochilodus argenteus, an important commercial and recreational fish in the Sa??o Francisco River, to identify migrations and spawning areas and to determine linear home range. During two spawning seasons (2001-2003), we radio-tagged fish in three main-stem reaches downstream of Tre??s Marias Dam (TMD), located at river kilometer (rkm) 2,109. We tagged 10 fish at Tre??s Marias (TM), which is 5 km downstream of TMD; 12 fish at Pontal, which is 28 km downstream of TMD and which includes the mouth of the Abaete?? River, and 10 fish at Cilga, which is 45 km downstream of TMD. Late-stage (ripe) adults tagged in each area during the spawning season remained at or near the tagging site, except for four Cilga fish that went to Pontal and probably spawned. The Pontal area at the Abaete?? River mouth was the most important spawning site we found. Prespawning fish moved back and forth between main-stem staging areas upstream of the Abaete?? River mouth and Pontal for short visits. These multiple visits were probably needed as ripe fish waited for spawning cues from a flooding Abaete?? River. Some fish homed to prespaw ning staging areas, spawning areas, and nonspawning areas. The migratory style of zulega was dualistic, with resident and migratory fish. Total linear home range was also dualistic, with small (<26-km) and large (53-127-km) ranges. The locations of spawning areas and home ranges suggest that the Pontal group (which includes Cilga fish) is one population that occupies about 110 km. The Pontal population overlaps a short distance with a population located downstream of Cilga. Movements of late-stage TM adults suggest that the TM group is a separate population, possibly with connections to populations upstream of TMD. ?? Copyright by the American Fisheries Society 2006.

Transactions of the American Fisheries Society↗

USGS1997

Regional landslide-hazard evaluation using landslide slopes, Western Wasatch County, Utah

Landsliding has historically been one of the most damaging geologic hazards in western Wasatch County, Utah. Accordingly, we mapped and analyzed landslides (slumps and debris slides) in the area to provide an empirical basis for regional landslide-hazard evaluation. The 336 landslides in the 250-sq-mi (650-km 2 ) area involve 20 geologic units, including Mississippian- to Quaternary-aged rock and unconsolidated deposits. Landsliding in western Wasatch County is characterized by a strong correlation between geologic material and landslide-slope inclination. From a simple statistical analysis of overall slope inclinations of late Holocene landslides, we determined “critical” slope inclinations above which late Holocene landsliding has typically occurred and used these as the primary basis for defining relative landslide hazard. The critical slopes vary for individual geologic units and range from 15 to 50 percent (9°–27°). The critical slope values and landslide locations were used in conjunction with geologic and slope maps to construct qualitative landslide-susceptibility maps for use by county planners. The maps delineate areas of low, moderate, and high relative hazard and indicate where studies should be completed prior to development to evaluate site-specific slope-stability conditions. Critical slopes as determined in this study provide a consistent empirical reference that is useful for evaluating relative landslide hazard and guiding land-use-planning decisions in large, geologically complex areas.

Utah↗

USGS1969

Water resources investigation program for Rio Aconcagua Valley, Chile

This report, prepared at the request of the Government of Chile under the auspices of the U. S. Agency for International Development (US AID), is based on a 2-month assignment (Oct. 22 to Dec. 31, 1969) of the author and outlines a program of water resources studies. The study program, if followed to its conclusion, will provide the basic hydrologic and hydrogeologic information and analysis essential for planning optimum future development and use of the water resources of the valley.

Open-File Report↗

USGS2003

Ecosystem history of southern and central Biscayne Bay: Summary report on sediment core analyses

During the last century, the environs of Biscayne Bay have been greatly affected by anthropogenic alteration through urbanization of the Miami/Dade County area. The sources, timing, delivery, and quality of freshwater flow into the Bay have been changed by construction of a complex canal system that controls movement of water throughout south Florida. Changes in shoreline and sub-aquatic vegetation and marine organisms have been observed and changes in water delivery are believed to be the cause. Current restoration goals are attempting to restore natural flow of fresh water into Biscayne and Florida Bays and to restore the natural fauna and flora, but first we need to determine pre-alteration baseline conditions in order to establish targets and performance measures for restoration. This research is part of an ongoing study designed to address the needs of the Biscayne Bay Coastal Wetlands Project (BBCW) of the Comprehensive Everglades Restoration Plan (CERP). By establishing the natural patterns of temporal change in salinity, water quality, vegetation, and benthic fauna in Biscayne Bay and the nearby wetlands over the last 100- 500 years the USGS, in collaboration with our partners, will provide the data necessary to set realistic targets to achieve the BBCW Project goals. Six cores from three sites in Biscayne Bay were collected in April 2002 for multidisciplinary multi-proxy analyses. This report details the results of these analyses and compares the 2002 cores to cores collected in 1997. The following are our significant findings to date: The salinity of central Biscayne Bay has become increasingly marine and increasingly stable over the last 100 years. At No Name Bank, prior to approximately 1915, the inter-decadal and decadal salinity fluctuations appear to have been greater than after 1915 when salinities stabilized at that site. Continental shelf/open marine influence on the sites has increased during the 20th century. There is no indication of inter-decadal salinity extremes or periods of hypersalinity. Freshwater and mesohaline salinities have had a minor influence on No Name bank throughout the time of deposition. At Featherbed Bank, the influence is reduced to mesohaline salinities. Card Bank has experienced relatively large swings in salinity over multi-decadal and centennial timescales, compared to central Biscayne Bay, but marine influence at the site has increased over the last century. Indications of regional scale patterns have been found, especially in the shell chemistry data and the pollen assemblages. These regional patterns indicate that the changes are not site specific and may not be limited to Biscayne Bay. Sub-aquatic vegetation has undergone bay-wide patterns of change over the last 200-500 years, which includes expansion prior to 1900 and declines during the last century in central Biscayne Bay. Thalassia appears to have increased at all three core sites sometime between 1550 and 1750 AD. A decline in Thalassia appears to have occurred after 1950 at No Name Bank and slightly earlier in the 20th century at Featherbed Bank. Card Bank does not appear to have experienced any declines in vegetation on an inter-decadal scale during the 20th century. Molluscan faunal abundance and diversity have undergone significant changes in central Biscayne Bay. Indicators of increased organic-rich sediments at No Name occur between 1869 to 1888 and between the 1930’s to 1975. These changes may correlate to human activities (settlement, population growth). These findings represent a first step towards the project’s goal to reconstruct the history of Biscayne Bay and they provide us with a working model to be tested at other sites. It is clear from our findings that Biscayne Bay has been a dynamic environment over the last 500 years, with natural changes occurring in salinity and benthic habitats. However, several significant changes have occurred in the 20th century: 1) increased stabilization of marine salinities; 2) declines in seagrass in central Biscayne Bay; 3) dramatic changes in molluscan abundance and diversity in central Biscayne Bay. The question remains - how do we better differentiate natural cycles of change from anthropogenic change within these observed trends? The preliminary implications from our research are that changes in salinity and benthic habitats have occurred naturally in Biscayne Bay on inter-decadal to centennial scales, perhaps due to climatic changes, changes in sea level, bank migrations, or a combination of factors. However, further work needs to be done to determine which components of change in the 20th century are human-induced and which are natural. By examining the historical records preserved in the sediments of Biscayne Bay, we can provide restoration trust agencies with the information necessary to set realistic targets and performance measures for Biscayne Bay.

Florida↗

USGS2007

Field-based evaluations of sampling techniques to support long-term monitoring of riparian ecosystems along wadeable streams on the Colorado Plateau

To better plan for and implement long-term ecological monitoring, we measured riparian vegetation and fluvial geomorphic features at pilot study sites on four wadeable perennial stream reaches, representative of drainages across the Colorado Plateau. Our primary objectives were to (1) collect field data, (2) evaluate the efficiency and effectiveness of various ecological measures and measurement techniques for riparian ecosystems, and (3) use field-based sampling to inform and refine the development of standard operating procedures for use in implementing integrated, long-term monitoring of riparian ecosystems. Ultimately, this work was aimed at providing NPS staff with some of the information and methods needed to design and implement long-term monitoring of NPS riparian resources, which is both relevant to management, and fully operational within institutional resource constraints. Our results suggest that selecting sampling reaches and establishing a sampling frame of 11 transects, across a range of stream types, is feasible given a limited set of decision rules. A distinctive feature of richness across all sites was the high percentage of rare species, defined here as species having a single occurrence at a site. Rare species represented from 33 percent to 47 percent of the species total across the four pilot sites. Our data show that the two smallest quadrat sizes, 0.01 m 2 and 0.1 m 2 , rarely had any species that occurred in the desired frequency range and can be omitted from the monitoring protocol. Few species fell within the 30–70 percent range in the 1-m 2 quadrats, but this quadrat size appears to be useful at the Tsaile Creek (CACH) site. We recommend continuing to collect information at the 1-m 2 scale and reevaluating its usefulness after more data are available from different types of sites. The 10-m 2 quadrat is adequate for monitoring changes in frequencies of very common species at all sites. Based on pilot study results, we conclude that at sites with low total species numbers (< 60 species), 40–60, 10-m 2 quadrats, would be sufficient to characterize overall species diversity for relatively common species. At sites with higher total numbers of species (> 100), 60–80, 10-m 2 quadrats would be required to characterize overall species diversity. Rare species of interest should be monitored using alternative approaches, such as a site inventory and/or mapping (see Elzinga and others, 1998). A large number of the systematically placed 10-m 2 quadrats span two or more geomorphic surfaces, especially adjacent to the channel. This makes resolution of species affinities with distinct geomorphic landforms difficult. Thus, we provide an amendment to improve characterization of herbaceous and shrub species on narrow, near-channel surfaces by sampling additional 0.5-m by 1-m quadrats on those surfaces. It appears that for sites in narrow valley settings where riparian zones average less than approximately 40 m, the number of 10-m 2 quadrats systematically placed on 11 transects will not provide shrub cover estimates at 20 percent precision. In such cases, additional sample reaches should be added in order to attain a minimum of 130 to 140 10-m 2 shrub quadrats. The line-intercept technique can provide a relatively rapid, reach-scale quantification of proportional cover for woody vegetation and geomorphic surface types and that variance in these measures stabilizes by the eighth or ninth transect sampled. An overlay of the distribution of geomorphic surface data derived from line-intercept sampling on topographic survey information indicates that delineation of geomorphic surfaces could be done in conjunction with the topographic survey of each transect, obviating the need to record surface breaks using the line intercept. To include geomorphic surface identifications with the topographic survey, surface breaks and transitional surfaces should be included and identified in the survey, in addition to systematically placed survey points. Compared to 5-m by 20-m tree quadrats, belt transects were shown to provide similar estimates of stand structure (stem density and stand basal area) in less than 30 percent of the time. Further, for the streams sampled, there were no statistically significant differences in stem density and basal area estimates between 10-m and 20-m belt transects and the smaller belts took approximately half the time to sample. There was, however, high variance associated with estimates of stand structure for infrequently occurring stems, such as large, relict or legacy riparian trees. Legacy riparian trees occurred in limited numbers at all sites sampled. A reachscale population census of these trees indicated that the 10-m belt transects tended to underestimate both stem density and basal area for these riparian forest elements and that a complete reach-scale census of legacy trees averaged less than one hour per site.

Colorado Plateau↗