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USGS2015

Fire history of Everglades National Park and Big Cypress National Preserve, southern Florida

Fire occurs naturally in the environment on most continents, including Africa (Ryan and Williams, 2011), Asia (Kauhanen, 2008), Australia (Kutt and Woinarski, 2007), Europe (Eshel and others, 2000), South America (Fidelis and others, 2010), and North America (Van Auken, 2000). Antarctica appears to be the only continent that has no reported natural fires, although fire is common in grasslands of Patagonia and on islands in the Subantarctic region (Gonzalez and others, 2005; McGlone and others, 2007). Natural fires also have occurred over thousands of years, and the frequencies of these natural fires have changed (Power and others, 2008). This has resulted in altered ecosystems at landscape scales. Recent evidence suggests that the treeless desert pastures of Tibet once were forests and woodlands, and charcoal deposits indicate that fire was more frequent in the past (Miehe and others, 2006). Human cultural development has been influenced by changes in natural fire frequencies. Zong and others (2007) reported that human suppression of fires in coastal areas of China allowed the development of rice paddy cultivation and, thus, increased the size of human populations. In addition to its almost world-wide occurrence, fire plays a role in a wide variety of ecosystem types. Grassland, savanna, steppe, woodland, forest, and wetland ecosystems all have fire as part of their natural ecology (Veblen and Lorenz, 1988; Chokkalingam and others, 2007; Miller and others, 2009, Keith and others, 2010; Staver and others, 2011). Fires affect these ecosystems in various ways, the most obvious of which is the direct effect on plant biomass (for example, Van Wilgen, 1982; Mack and others, 2008). However, fire has many other effects on ecosystems. Plant species richness, diversity, and functional types can change in response to fire (Peterson and Reich, 2008). All properties of the surface soils (such as bulk density, particle size distribution, pH, and organic carbon and nitrogen content) can be altered by the frequency and severity of fire (Boerner and others, 2009). Faunal communities will respond to fire, with some species increasing (Fuhlendorf and others, 2006) and other species decreasing, after the fire (Vasconcelos and others, 2009).The position of the ecotone between differing ecosystems also is influenced by fire occurrence (Heisler and others, 2003; Briggs and others, 2005; Smith and others, 2013). Fire has been used as a management tool in various ecosystems around the world. Prairies, grasslands, and savannas are fire-maintained ecosystems where fire is used to deter invasion by shrubs and trees (Grant and others, 2009; Scheintaub and others, 2009). Similarly, fire plays an important role in woodlands and forests by influencing species composition and succession such, as the use of fire in coniferous forests to prevent encroachment by hardwoods (Phillippe and others, 2011). Fire also has been used to manage wetland ecosystems for more than 50 years (Lynch, 1941; Frost, 1995). Uses have included returning marshes to early successional states, increasing forage for wildlife (Lynch, 1941). In all fire-influenced ecosystems, prescribed burns are routinely used to reduce fuel loads, reducing the possibility of catastrophic fires.

Florida↗

USGS2015

Global Cropland Area Database (GCAD) derived from Remote Sensing in Support of Food Security in the Twenty-first Century: Current Achievements and Future Possibilities

The precise estimation of the global agricultural cropland- extents, areas, geographic locations, crop types, cropping intensities, and their watering methods (irrigated or rainfed; type of irrigation) provides a critical scientific basis for the development of water and food security policies (Thenkabail et al., 2012, 2011, 2010). By year 2100, the global human population is expected to grow to 10.4 billion under median fertility variants or higher under constant or higher fertility variants (Table 1) with over three quarters living in developing countries, in regions that already lack the capacity to produce enough food. With current agricultural practices, the increased demand for food and nutrition would require in about 2 billion hectares of additional cropland, about twice the equivalent to the land area of the United States, and lead to significant increases in greenhouse gas productions (Tillman et al., 2011). For example, during 1960-2010 world population more than doubled from 3 billion to 7 billion. The nutritional demand of the population also grew swiftly during this period from an average of about 2000 calories per day per person in 1960 to nearly 3000 calories per day per person in 2010. The food demand of increased population along with increased nutritional demand during this period (1960-2010) was met by the “green revolution” which more than tripled the food production; even though croplands decreased from about 0.43 ha/capita to 0.26 ha/capita (FAO, 2009). The increase in food production during the green revolution was the result of factors such as: (a) expansion in irrigated areas which increased from 130 Mha in 1960s to 278.4 Mha in year 2000 (Siebert et al., 2006) or 399 Mha when you do not consider cropping intensity (Thenkabail et al., 2009a, 2009b, 2009c) or 467 Mha when you consider cropping intensity (Thenkabail et al., 2009a; Thenkabail et al., 2009c); (b) increase in yield and per capita food production (e.g., cereal production from 280 kg/person to 380 kg/person and meat from 22 kg/person to 34 kg/person (McIntyre, 2008); (c) new cultivar types (e.g., hybrid varieties of wheat and rice, biotechnology); and (d) modern agronomic and crop management practices (e.g., fertilizers, herbicide, pesticide applications). However, some of the factors that lead to the green revolution have stressed the environment to limits leading to salinization and decreasing water quality. For example, from 1960 to 2000, the phosphorous use doubled from 10 million tons to 20 MT, pesticide use tripled from near zero to 3 MT, and nitrogen use as fertilizer increased to a staggering 80 MT from just 10 MT (Foley et al., 2007; Khan and Hanjra, 2008). Further, diversion of croplands to bio-fuels is already taking water away from food production; the economics, carbon sequestration, environmental, and food security impacts of biofuel production are net negative (Lal and Pimentel, 2009), leaving us with a carbon debt (Gibbs et al., 2008; Searchinger et al., 2008). Climate models predict that in most regions of the world the hottest seasons on record will become the norm by the end of the century-an outcome that bodes ill for feeding the world (Kumar and Singh, 2005). Also, crop yield increases of the green revolution era have now stagnated (Hossain et al., 2005). Thereby, further increase in food production through increase in cropland areas and\or increased allocations of water for croplands are widely considered unsustainable and\or infeasible. Indeed, cropland areas have even begun to decrease in many 3 parts of the World due to factors such as urbanization, industrialization, and salinization. Furthermore, ecological and environmental imperatives such as biodiversity conservation and atmospheric carbon sequestration have put a cap on the possible expansion of cropland areas to other lands such as forests and rangelands. Other important factors limit food security. These include factors such as diversion of croplands to biofuels (Bindraban et al., 2009), limited water resources for irrigation expansion (Turral et al., 2009), limits on agricultural intensifications, loss of croplands to urbanization (Khan and Hanjra, 2008), increasing meat consumption (and associated demands on land and water) (Vinnari and Tapio, 2009), environmental infeasibility for cropland expansion (Gordon et al., 2009), and changing climate have all put pressure on our continued ability to sustain global food security in the twenty-first century. So, how does the World continue to meet its food and nutrition needs?. Solutions may come from bio-technology and precision farming, however developments in these fields are not currently moving at rates that will ensure global food security over next few decades. Further, there is a need for careful consideration of possible harmful effects of bio-technology. We should not be looking back 30– 50 years from now, like we have been looking back now at many mistakes made during the green revolution. During the green revolution the focus was only on getting more yield per unit area. Little thought was put about serious damage done to our natural environments, water resources, and human health as a result of detrimental factors such as uncontrolled use of herbicides-pesticides-nutrients, drastic groundwater mining, and salinization of fertile soils due to over irrigation. Currently, there is talk of a “second green revolution” or even an “ever green revolution”, but clear ideas on what these terms actually mean are still debated and are evolving. One of the biggest issues that are not given adequate focus is the use of large quantities of water for food production. Indeed, an overwhelming proportion (60-90%) of all human water use in India goes for producing their food (Falkenmark, M., & Rockström, 2006). But such intensive water use for food production is no longer tenable due to increasing pressure for water use alternatives such as increasing urbanization, industrialization, environmental flows, bio-fuels, and recreation. This has brought into sharp focus the need to grow more food per drop of water leading to a “blue revolution”

Book chapter↗

USGS2025

Desert ecosystems shape diversification in glossy snakes (genus Arizona) requiring a re-alignment of evolutionary and conservation units

Subspecies are often targets for conservation, yet many lack the genetic data necessary to validate their status as distinctive evolutionary lineages. In 2016, conservationists faced this issue when designating the California glossy snake, Arizona elegans occidentalis , as a Species of Special Concern in California, a decision prompted by population declines and habitat loss but absent of genetic information about its evolutionary integrity. To address this knowledge gap, we collected genomic and mitochondrial data from a rangewide sample of the Arizona elegans complex ( n = 257) and characterized genetic structure at varying spatial scales. We confirmed an east–west phyletic division within the A. elegans complex that correlates with an ecotone between the Sonoran and Chihuahuan Deserts and pinpoint the separation to a ∼20 km area in southeastern Arizona, USA. Individuals recognized as A. e. occidentalis do not form a genetically cohesive unit within a more inclusive western clade that is sister to the endemic Arizona pacata in Baja California, México. We synonymize four subspecies circumscribed by the western clade and recognize a new species Arizona occidentalis to re-align the taxonomy with the phylogeographic structure. Most of the diversity within A. occidentalis occurs in California, with three major lineages corresponding separate desert biomes. We revise the conservation units within A. occidentalis to mirror these lineages and address concerns regarding habitat loss in transitional environments along the western edge of its range. This work underscores the importance of aligning taxonomy, evolutionary identity, and management units to design the most effective conservation strategies.

Molecular Phylogenetics and Evolution↗

USGS2026

Fish introductions related to strong and diversifying effects on zooplankton assemblages in high-elevation mountain lakes

Freshwater environments are threatened by multiple anthropogenic stressors. High-elevation mountain lakes are particularly vulnerable to introduced nonnative fish and nutrient deposition because they were historically fishless and typically oligotrophic. To understand the potential effects of fish introduction and nutrient levels on high-elevation lake ecosystems, we assessed differences in zooplankton size, biomass, and density in 76 alpine and subalpine lakes in the Wind River Range, Wyoming, USA, and related those differences to the presence of introduced trout and to food quality (seston nutrient content) and quantity (chlorophyll a concentration). Trout presence, and to a lesser extent trout species, were the strongest predictors of zooplankton composition. Fishless lakes were dominated by low densities of copepods and other large-bodied taxa, and lakes with introduced trout were dominated by high densities of cladocerans, rotifers, and other small-bodied taxa. These assemblage differences are likely because trout reduce or eliminate all large zooplankton taxa by size-selective predation, including predation on Hesperodiaptomus shoshone (S. A. Forbes, 1893), a keystone species that effectively controls populations of rotifers and small crustacean zooplankton taxa. In contrast, the quantity and quality of seston was not associated with zooplankton assemblages. Zooplankton composition in lakes with Rocky Mountain Cutthroat Trout Oncorhynchus virginalis (Girard, 1856) or Golden Trout Oncorhynchus aguabonita (Jordan, 1892) was highly variable, but in lakes with primarily Brook Trout Salvelinus fontinalis (Mitchill, 1814), zooplankton composition was consistently distinct from that in fishless lakes, suggesting that Brook Trout introductions altered the zooplankton assemblage to a greater extent than Cutthroat or Golden trout did. These results contribute to global evidence that predatory fish introductions fundamentally restructure alpine lake food webs. The slow or incomplete recovery of native zooplankton assemblages following fish removal suggests long-term ecological legacies of fish introductions and highlights the importance of understanding factors that promote resilience in high-elevation lake ecosystems.

Wyoming↗

USGS2013

Basin-scale phenology and effects of climate variability on global timing of initial seaward migration of Atlantic salmon (Salmo salar)

Migrations between different habitats are key events in the lives of many organisms. Such movements involve annually recurring travel over long distances usually triggered by seasonal changes in the environment. Often, the migration is associated with travel to or from reproduction areas to regions of growth. Young anadromous Atlantic salmon ( Salmo salar ) emigrate from freshwater nursery areas during spring and early summer to feed and grow in the North Atlantic Ocean. The transition from the freshwater (‘parr’) stage to the migratory stage where they descend streams and enter salt water (‘smolt’) is characterized by morphological, physiological and behavioural changes where the timing of this parr-smolt transition is cued by photoperiod and water temperature. Environmental conditions in the freshwater habitat control the downstream migration and contribute to within- and among-river variation in migratory timing. Moreover, the timing of the freshwater emigration has likely evolved to meet environmental conditions in the ocean as these affect growth and survival of the post-smolts. Using generalized additive mixed-effects modelling, we analysed spatio-temporal variations in the dates of downstream smolt migration in 67 rivers throughout the North Atlantic during the last five decades and found that migrations were earlier in populations in the east than the west. After accounting for this spatial effect, the initiation of the downstream migration among rivers was positively associated with freshwater temperatures, up to about 10 °C and levelling off at higher values, and with sea-surface temperatures. Earlier migration occurred when river discharge levels were low but increasing. On average, the initiation of the smolt seaward migration has occurred 2.5 days earlier per decade throughout the basin of the North Atlantic. This shift in phenology matches changes in air, river, and ocean temperatures, suggesting that Atlantic salmon emigration is responding to the current global climate changes.

Global Change Biology↗

USGS2013

Riverine habitat dynamics

The physical habitat template is a fundamental influence on riverine ecosystem structure and function. Habitat dynamics refers to the variation in habitat through space and time as the result of varying discharge and varying geomorphology. Habitat dynamics can be assessed at spatial scales ranging from the grain (the smallest resolution at which an organism relates to its environment) to the extent (the broadest resolution inclusive of all space occupied during its life cycle). In addition to a potentially broad range of spatial scales, assessments of habitat dynamics may include dynamics of both occupied and nonoccupied habitat patches because of process interactions among patches. Temporal aspects of riverine habitat dynamics can be categorized into hydrodynamics and morphodynamics. Hydrodynamics refers to habitat variation that results from changes in discharge in the absence of significant change of channel morphology and at generally low sediment-transport rates. Hydrodynamic assessments are useful in cases of relatively high flow exceedance (percent of time a flow is equaled or exceeded) or high critical shear stress, conditions that are applicable in many studies of instream flows. Morphodynamics refers to habitat variation resulting from changes to substrate conditions or channel/floodplain morphology. Morphodynamic assessments are necessary when channel and floodplain boundary conditions have been significantly changed, generally by relatively rare flood events or in rivers with low critical shear stress. Morphodynamic habitat variation can be particularly important as disturbance mechanisms that mediate population growth or for providing conditions needed for reproduction, such as channel-migration events that erode cutbanks and provide new pointbar surfaces for germination of riparian trees. Understanding of habitat dynamics is increasing in importance as societal goals shift toward restoration of riverine ecosystems. Effective investment in restoration strategies requires that the role of physical habitat is correctly diagnosed and that restoration activities address true habitat limitations, including the role of dynamic habitats.

Book chapter↗

USGS2002

A Geochemical Trophic Cascade in Yellowstone's Geothermal Environments

We contrast the geochemistry of the Madison drainage, which has high concentrations of geothermal features, with the Lamar drainage of Yellowstone National Park, USA, and trace the consequences of geochemical differences through abiotic and biotic linkages in the ecosystem. Waters in the geothermal-dominated drainage contained anomalously high levels of fluoride (F) and silica (SiO 2 ). Soils, stream sediments, and surface waters that interact or mix with geothermal waters, in turn, had elevated F and SiO 2 concentrations compared to similar samples from the Lamar drainage. The geochemical differences were reflected in the chemistry of forage plants, with some plants from geothermally influenced areas containing four- to eightfold higher concentrations of F and SiO 2 than similar plants in the Lamar drainage. Geothermal heat reduced snowpack, and we found that elk (Cervus elaphus) concentrated in these refugia as snowpack increased each winter. The consequent high dietary intake of F in animals associated with the geothermal areas was confirmed by the finding that bone samples from elk living in the Madison drainage contained sixfold higher concentrations of F than samples collected from animals wintering in the Lamar drainage. High F exposure resulted in compromised dentition due to fluoride toxicosis, which was undoubtedly exacerbated by the abrasive action of silica. The consequent accelerated and aberrant tooth wear resulted in early onset of senescence, reduced life span, and an abbreviated age structure. We speculate that these altered demographics, combined with spatial heterogeneity of snowpack, will result in increased vulnerability of this large herbivore population to wolf predation and less resiliency to compensate demographically for predation.

Wyoming↗

USGS2026

Growth, movement, and survival of precocial shorebird chicks are constrained by their environment.

Young animals are often less mobile than adults, while also having high energetic demands. They may therefore be more vulnerable to local-scale changes in environmental conditions. In particular, when 1 sex must grow more rapidly than the other to achieve a larger adult size, that sex may experience especially dramatic reductions in growth and survival in the face of suboptimal environmental conditions. In order to investigate the flexibility of individuals in response to local-scale environmental variation during development, we studied the sex-specific growth, movement, and survival of Hudsonian Godwit ( Limosa haemastica ) chicks—a sexually dimorphic, precocial shorebird that breeds in the sub-Arctic and exhibits a male-skewed adult sex ratio. We found that female chicks—which must grow to a larger adult size—reached their maximum growth rates at a later age, but had similar growth rates to males before that and survived equally well to 21 days. We also found that, irrespective of sex, chicks had reduced movement rates when they were young and/or temperatures were cold, and only weakly increased their movement rates when invertebrate abundances remained low across an entire week. Early in life, godwit chicks may therefore be constrained from increasing their foraging efforts by local environmental conditions, forcing females to sustain higher growth rates late in the season past the local resource peak. Such sex-specific vulnerabilities could lead to lower early-life survival and, in turn, skewed adult sex ratios, which have important implications for population dynamics and persistence.

Behavioral Ecology↗

USGS2024

Retention of p-Chip microtransponders and posttagging survival of small-bodied stream fishes

Objective Obtaining demographic rates often requires complex open-population capture–mark–recapture (CMR) study designs. Conducting such studies for small-bodied fishes has been limited in part by excessive mortality after tagging procedures and poor tag retention. As new tag types emerge, information regarding fish survival and tag retention over varying time scales may benefit resource managers to effectively plan future CMR studies. The p-Chip microtransponder is a 500- × 500- × 100-μm tag that is inserted subcutaneously and is read with a handheld laser. Each tag contains a nine-digit unique identification number. P-Chip microtransponder tags have been used on a limited number of small-bodied fishes, with relatively high rates observed for fish survival and tag retention. Information on posttagging survival and retention of p-Chip microtransponder tags across a range of small-bodied fish species and tagging locations is needed to inform their effectiveness in future CMR studies. Methods We quantified survival and tag retention after p-Chip microtransponder implantation in Creek Chub Semotilus atromaculatus and Northern Pearl Dace Margariscus nachtriebi in a laboratory environment, and retention of p-Chip microtransponder tags in Northern Pearl Dace was also quantified over a year-long field study. We marked 56 Creek Chub and 9 Northern Pearl Dace in the laboratory with p-Chip microtransponder tags and compared them to an equal number of unmarked individuals over 90 days. We marked 1990 Northern Pearl Dace and conducted recapture events through four seasons (June, September, and October 2022 and June 2023) in four headwater streams of Nebraska. Result Survival for Creek Chub was 85% (standard error [SE] = 5.9) and did not differ from control fish survival (95%; SE = 3.2) in the 90-day laboratory experiment. Survival for Northern Pearl Dace was 89% (SE = 11.0) and did not differ from that of control fish (100%) in the laboratory experiment. Tag retention was 89% (SE = 4.6) for Creek Chub and 100% for Northern Pearl Dace in the laboratory. The p-Chip microtransponder performed well during the CMR field study, with tag retention for Northern Pearl Dace at 94% across 374 days. Conclusion Our results suggest that the p-Chip microtransponder minimally affected small-bodied fish survival and had high tag retention in both the laboratory and field studies. Thus, the p-Chip microtransponder tag may be appropriate for use in small-bodied fishes when individual identification is needed in a CMR study.

North American Journal of Fisheries Management↗

USGS2015

Variability of intertidal foraminferal assemblages in a salt marsh, Oregon, USA

We studied 18 sampling stations along a transect to investigate the similarity between live (rose Bengal stained) foraminiferal populations and dead assemblages, their small-scale spatial variations and the distribution of infaunal foraminifera in a salt marsh (Toms Creek marsh) at the upper end of the South Slough arm of the Coos Bay estuary, Oregon, USA. We aimed to test to what extent taphonomic processes, small-scale variability and infaunal distribution influence the accuracy of sea-level reconstructions based on intertidal foraminifera. Cluster analyses have shown that dead assemblages occur in distinct zones with respect to elevation, a prerequisite for using foraminifera as sea-level indicators. Our nonparametric multivariate analysis of variance showed that small-scale spatial variability has only a small influence on live (rose Bengal stained) populations and dead assemblages. The dissimilarity was higher, however, between live (rose Bengal stained) populations in the middle marsh. We observed early diagenetic dissolution of calcareous tests in the dead assemblages. If comparable post-depositional processes and similar minor spatial variability also characterize fossil assemblages, then dead assemblage are the best modern analogs for paleoenvironmental reconstructions. The Toms Creek tidal flat and low marsh vascular plant zones are dominated by Miliammina fusca , the middle marsh is dominated by Balticammina pseudomacrescens and Trochammina inflata , and the high marsh and upland–marsh transition zone are dominated by Trochamminita irregularis . Analysis of infaunal foraminifera showed that most living specimens are found in the surface sediments and the majority of live (rose Bengal stained) infaunal specimens are restricted to the upper 10 cm, but living individuals are found to depths of 50 cm. The dominant infaunal specimens are similar to those in the corresponding surface samples and no species have been found living solely infaunally. The total numbers of infaunal foraminifera are small compared to the total numbers of dead specimens in the surface samples. This suggests that surface samples adequately represent the modern intertidal environment in Toms Creek.

Oregon↗

USGS2017

Interactive effects of water temperature and salinity on growth and mortality of eastern oysters, Crassostrea virginica: A meta-analysis using 40 years of monitoring data

Despite nearly a century of exploitation and scientific study, predicting growth and mortality rates of the eastern oyster ( Crassostrea virginica ) as a means to inform local harvest and management activities remains difficult. Ensuring that models reflect local population responses to varying salinity and temperature combinations requires locally appropriate models. Using long-term (1988 to 2015) monitoring data from Louisiana's public oyster reefs, we develop regionally specific models of temperature- and salinity-driven mortality (sack oysters only) and growth for spat (<25 mm), seed (25–75 mm), and sack (>75 mm) oyster size classes. The results demonstrate that the optimal combination of temperature and salinity where Louisiana oysters experience reduced mortality and fast growth rates is skewed toward lower salinities and higher water temperatures than previous models have suggested. Outside of that optimal range, oysters are commonly exposed to combinations of temperature and salinity that are correlated with high mortality and reduced growth. How these combinations affect growth, and to a lesser degree mortality, appears to be size class dependent. Given current climate predictions for the region and ongoing large-scale restoration activities in coastal Louisiana, the growth and mortality models are a critical step toward ensuring sustainable oyster reefs for long-term harvest and continued delivery of the ecological services in a changing environment.

Louisiana↗

USGS1975

Water and the South Florida environment

Ecological problems are a major concern to Florida as well as to the Nation. National attention was focused on these problems in September 1968, when the Port Authority of Dade County began to con- struct a jetport for supersonic aircraft on a 39-square-mile tract 6 miles north of Everglades National Park and on the east edge of the Big Cypress Swamp. Conservation groups and citizens raised questions as to the effects of a regional jetport and the attendant satellite growth on the water resources and biological communities of the National Park. The Department of the Interior began studies to investigate the situation. One study, Leopold (1969), reported on the unfavorable ecological effects of the attendant satellite growth. Then Secretary of the Interior, Walter J. Hickel, directed the U.S. Geological Survey to study the water resources of the Big Cypress to determine which parts of the Big Cypress contribute the major part of the water necessary to maintain adequate water supplies for Everglades National Park. This was done in a report by Klein and others (1970). At about the same time, the Departments of interior and Transportation, the State of Florida, and the Dade County Port Authority con-curred in assigning to the Secretary of the Interior certain responsibilities for planning, developing, and coordinating an ecological study of south Florida. A primary objective of the ecological study is to provide information that will assist in the formulation of land-use policy consistent with the protection of the environment of Everglades National Park, the adjacent estuaries, and the public water supplies. The part of the investigation describing the surface-water and ground-water resources of south Florida was assigned to the Geological Survey. The quantity and quality of surface water and ground water and their interrelation with estuarine and marine waters are here considered. Also considered are the problems, present or future, related to the hydrologic environment that involve human, animal, and plant life. Changes taking place, apparent trends, and projections for the future are also considered, as well as alternatives for water management. The Geological Survey effort began in January 1971, when aerial photography and selected qualitative hydrologic data were obtained. However, most of the information upon which this report Is based was obtained by the Geological Survey in cooperative programs with several local, State, and Federal agencies since about 1940. The long-term support of the U.S. Army Corps of Engineers, the National Park Service, U.S. Navy, Florida Department of Natural Resources, Central and Southern Florida Flood Control District, Dade, Broward, Palm Beach and Collier Counties, Miami and Miami Beach, Ft. Lauderdale, Naples and others in the collection of data is gratefully acknowledged. A prolonged drought throughout south Florida from September 1970 to May 1971 accentuated the importance and timeliness of the study. The drought brought about a readvance of sea-water intrusion in many coastal areas, which necessitated restrictions on water use. The effect of drought on the regional water supply, continued population growth and increased water demands, and deterioration of the water quality in many of the canals and waterways of the urban areas accentuated the need for improved water management and land-use planning. As a result of the water crisis, the Governor of Florida called a special conference in September 1971. The conference, attended by foremost scientific and government personnel, proposed creation of an agency that would develop and implement comprehensive land and water-use plans for south Florida that would minimize environmental degradation.

Florida↗

USGS2009

Rebuttal of "Polar bear population forecasts: a public-policy forecasting audit"

Observed declines in the Arctic sea ice have resulted in a variety of negative effects on polar bears ( Ursus maritimus ). Projections for additional future declines in sea ice resulted in a proposal to list polar bears as a threatened species under the United States Endangered Species Act. To provide information for the Department of the Interior's listing-decision process, the US Geological Survey (USGS) produced a series of nine research reports evaluating the present and future status of polar bears throughout their range. In response, Armstrong et al. [Armstrong, J. S., K. C. Green, W. Soon. 2008. Polar bear population forecasts: A public-policy forecasting audit. Interfaces 38 (5) 382–405], which we will refer to as AGS, performed an audit of two of these nine reports. AGS claimed that the general circulation models upon which the USGS reports relied were not valid forecasting tools, that USGS researchers were not objective or lacked independence from policy decisions, that they did not utilize all available information in constructing their forecasts, and that they violated numerous principles of forecasting espoused by AGS. AGS (p. 382) concluded that the two USGS reports were "unscientific and inconsequential to decision makers." We evaluate the AGS audit and show how AGS are mistaken or misleading on every claim. We provide evidence that general circulation models are useful in forecasting future climate conditions and that corporate and government leaders are relying on these models to do so. We clarify the strict independence of the USGS from the listing decision. We show that the allegations of failure to follow the principles of forecasting espoused by AGS are either incorrect or are based on misconceptions about the Arctic environment, polar bear biology, or statistical and mathematical methods. We conclude by showing that the AGS principles of forecasting are too ambiguous and subjective to be used as a reliable basis for auditing scientific investigations. In summary, we show that the AGS audit offers no valid criticism of the USGS conclusion that global warming poses a serious threat to the future welfare of polar bears and that it only serves to distract from reasoned public-policy debate.

Interfaces↗

USGS2006

Ecology of a population of subsidized predators: Common ravens in the central Mojave Desert, California

Human subsidies have resulted in the rapid growth of populations of common ravens (Corvus corax) in the Mojave Desert. This is a management concern because ravens prey on threatened desert tortoises (Gopherus agassizii). We conducted weekly counts for 29 months at 10 sites on the US Army's National Training Center, Fort Irwin, California to evaluate factors affecting the distribution of ravens. Raven abundance varied seasonally, diurnally, and with human abundance. It was greatest near resource subsidies, specifically the landfill and sewage ponds. Although other studies have documented heavy use of landfills by ravens, the use of sewage ponds had not been previously reported in the published literature. We suggest that raven management should focus on reducing access to anthropogenic resources. ?? 2006.

Journal of Arid Environments↗

USGS2013

The impact of small irrigation diversion dams on the recent migration rates of steelhead and redband trout ( Oncorhynchus mykiss )

Barriers to migration are numerous in stream environments and can occur from anthropogenic activities (such as dams and culverts) or natural processes (such as log jams or dams constructed by beaver ( Castor canadensis )). Identification of barriers can be difficult when obstructions are temporary or incomplete providing passage periodically. We examine the effect of several small irrigation diversion dams on the recent migration rates of steelhead ( Oncorhynchus mykiss ) in three tributaries to the Methow River, Washington. The three basins had different recent migration patterns: Beaver Creek did not have any recent migration between sites, Libby Creek had two-way migration between sites and Gold Creek had downstream migration between sites. Sites with migration were significantly different from sites without migration in distance, number of obstructions, obstruction height to depth ratio and maximum stream gradient. When comparing the sites without migration in Beaver Creek to the sites with migration in Libby and Gold creeks, the number of obstructions was the only significant variable. Multinomial logistic regression identified obstruction height to depth ratio and maximum stream gradient as the best fitting model to predict the level of migration among sites. Small irrigation diversion dams were limiting population interactions in Beaver Creek and collectively blocking steelhead migration into the stream. Variables related to stream resistance (gradient, obstruction number and obstruction height to depth ratio) were better predictors of recent migration rates than distance, and can provide important insight into migration and population demographic processes in lotic species.

Washington↗

USGS2019

Environmental DNA (eDNA) detection of nonnative bullseye snakehead in southern Florida

Bullseye Snakehead Channa marulius (Hamilton 1822) was first detected in the southern Florida town of Tamarac in 2000 and has been expanding its geographic range since. Environmental DNA (eDNA) analysis is a newly-developed technique used to noninvasively detect cryptic or low-density species or those that are logistically difficult-to-study. Genetic material shed into the environment through tissue and body fluids is concentrated from water samples and analyzed for the presence of target species eDNA. To help delineate Bullseye Snakehead’s geographic range, we developed and validated a species-specific eDNA assay for both quantitative and droplet digital PCR (ddPCR). We then used ddPCR to assess 16 locations in southeast Florida using 222 water samples collected from 2015 to 2018. Positive eDNA detections were obtained at all six locations that were within the known geographic range of Bullseye Snakehead. Furthermore, eDNA was detected in six of 10 locations that were previously thought to be outside the periphery of the range but hydrologically connected through the extensive canal system. Over the four years of sampling, estimated occurrence rates (ψ) remained stable and relatively high (ψ = 0.67 [95% credible interval (CI) 0.33–0.95]) near Tamarac, Florida, as compared to the most southern sampling locations (ψ = 0.0–0.37). Bulls- eye Snakehead eDNA estimated occurrence rates in the middle region increased between 2016 (0.28 [95% CI 0.03–0.94]) and 2017 (0.66 [95% CI 0.24–0.98]), potentially reflecting eDNA detections related to a growing or expanding population. Bullseye Snakehead eDNA was detected at low concentrations on the northern and eastern borders of Everglades National Park, which is an important conservation area and UNESCO World Heritage Site. Despite extensive sampling via electrofishing, no Bullseye Snakehead were visually detected in several locations that yielded positive eDNA samples. It is unclear whether eDNA was transported through flowing water or another vector. To date, collection records for this species are confined to urban canals; however, Bullseye Snakehead may use the interconnected system of canals to disperse to natural conservation areas such as Everglades National Park, Big Cypress National Preserve, and Water Conservation Areas, where it may impact native species via predation and competition.

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USGS1994

Waterfowl botulism--a brief summary

Botulism is a food poisoning caused by the ingestion of the toxin produced by the bacterium Clostridium botulinum of any of six strains, designated A through F. The disease, as it occurs in epidemic proportion in wild birds, is most commonly of the C type, although outbreaks caused by type E botulism have been observed on the Great Lakes. C. botulinum is a widely distributed anaerobic bacterium which is capable of existence for many years in spore form. Its vegetative cells grow and synthesize toxin, whenever and wherever the proper conditions exist in their environment. Outbreaks of botulism occur when aquatic birds consume this toxin which has been preformed in their food. Botulism is, therefore, an intoxication rather than an infection and is not a contagious disease. Botulism can be diagnosed conclusively only by demonstration of the toxin in the blood or serum of live affected birds, and a diagnostic laboratory should be contacted to confirm field diagnoses. A conclusive diagnosis cannot be reached by demonstrating the toxin or the organism in dead animals. The 'microenvironment concept' assumes that C. botulinum produces toxin in small, discrete, particulate food items which provide the requirements for growth of the bacteria independent of the surrounding wetland environment and which protect the toxin from dilution or inactivation. Optimum conditions for C. botulinum growth and toxin production include the absence of oxygen, a temperature of 76 deg. to 98 deg. F and suitable organic media, especially those composed of animal protein. Such conditions may be met in decaying invertebrate carcasses even though external conditions are unfavorable for toxin production. Vertebrate carcasses also may provide suitable conditions for the production of toxin, and maggots collected from duck carcasses during botulism outbreaks frequently contain extremely high levels of toxin. In determining the specific source of toxin and recommending control measures in the dynamic, complex, and diverse conditions of specific wetland ecosystem where botulism occurs, one's conclusions must necessarily become more speculative. Possibilities for reducing waterfowl losses due to botulism--Complete elimination of the causative organism, C. botulinum , from the wetland ecosystem is neither practical nor possible. Control methods may sometimes be profitably directed at prevention of toxin production, and the quantity of suitable media can be influenced. Rising water levels may drown terrestrial invertebrates, or flood vegetation thereby releasing nutrients which stimulate the increase in aquatic invertebrate populations to unstable levels which collapse. In other situations decreasing water levels may increase the numbers of invertebrate carcasses by increasing water temperatures or salinity which had been marginal for survival of previously thriving invertebrate populations or by stranding invertebrates on mud flats subject to periodic wind flooding. Therefore, a basic and important step in controlling botulism is stabilization of the wetland ecosystem in order to avoid the accumulation of decaying animal protein, especially during periods when temperatures are favorable for toxin production in these media. This can sometimes be accomplished by water level manipulation. If toxin production cannot be controlled by reducing the quantity of suitable media, another step is to prevent the ingestion of the toxic food items. Birds may be chased or lured from areas of toxin source or areas can be made less attractive by rapid and complete drainage, or draw down to a stable shoreline, where wind flooding does not occur. Removal of vertebrate carcasses, especially those of birds dying during the outbreak, reduces the availability of toxic maggots but carcass removal must be carried out frequently and diligently.Prevention of the effects of the toxin can be accomplished in some instances. Some degree of active immunity can be produced by injections of specific toxoi

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USGS2010

Southeast Regional Assessment Project for the National Climate Change and Wildlife Science Center, U.S. Geological Survey

The Southeastern United States spans a broad range of physiographic settings and maintains exceptionally high levels of faunal diversity. Unfortunately, many of these ecosystems are increasingly under threat due to rapid human development, and management agencies are increasingly aware of the potential effects that climate change will have on these ecosystems. Natural resource managers and conservation planners can be effective at preserving ecosystems in the face of these stressors only if they can adapt current conservation efforts to increase the overall resilience of the system. Climate change, in particular, challenges many of the basic assumptions used by conservation planners and managers. Previous conservation planning efforts identified and prioritized areas for conservation based on the current environmental conditions, such as habitat quality, and assumed that conditions in conservation lands would be largely controlled by management actions (including no action). Climate change, however, will likely alter important system drivers (temperature, precipitation, and sea-level rise) and make it difficult, if not impossible, to maintain recent historic conditions in conservation lands into the future. Climate change will also influence the future conservation potential of non-conservation lands, further complicating conservation planning. Therefore, there is a need to develop and adapt effective conservation strategies to cope with the effects of climate and landscape change on future environmental conditions. Congress recognized this important issue and authorized the U.S. Geological Survey (USGS) National Climate Change and Wildlife Science Center (NCCWSC; http://nccw.usgs.gov/) in the Fiscal Year 2008. The NCCWSC will produce science that will help resource management agencies anticipate and adapt to climate change impacts to fish, wildlife, and their habitats. With the release of Secretarial Order 3289 on September 14, 2009, the mandate of the NCCWSC was expanded to address climate change-related impacts on all Department of the Interior (DOI) resources. The NCCWSC will establish a network of eight DOI Regional Climate Science Centers (RCSCs) that will work with a variety of partners to provide natural resource managers with tools and information that will help them anticipate and adapt conservation planning and design for projected climate change. The forecasting products produced by the RCSCs will aid fish, wildlife, and land managers in designing suitable adaptive management approaches for their programs. The DOI also is developing Landscape Conservation Cooperatives (LCCs) as science and conservation action partnerships at subregional scales. The USGS is working with the Southeast Region of the U.S. Fish and Wildlife Service (FWS) to develop science collaboration between the future Southeast RCSC and future LCCs. The NCCWSC Southeast Regional Assessment Project (SERAP) will begin to develop regional downscaled climate models, land cover change models, regional ecological models, regional watershed models, and other science tools. Models and data produced by SERAP will be used in a collaborative process between the USGS, the FWS (LCCs), State and federal partners, nongovernmental organizations, and academia to produce science at appropriate scales to answer resource management questions. The SERAP will produce an assessment of climate change, and impacts on land cover, ecosystems, and priority species in the region. The predictive tools developed by the SERAP project team will allow end users to better understand potential impacts of climate change and sea level rise on terrestrial and aquatic populations in the Southeastern United States. The SERAP capitalizes on the integration of five existing projects: (1) the Multi-State Conservation Grants Program project "Designing Sustainable Landscapes," (2) the USGS multidisciplinary Science Thrust project "Water Availability for Ecological Needs," (3) the USGS Southeast Pilot Project "Climate Change in the Southeastern U.S. and its Impacts on Bird Distributions and Habitats," (4) a sea-level rise impacts study envisioned jointly with the National Oceanic and Atmospheric Administration (NOAA), and (5) two USGS sea-level rise impact assessment projects that address inundation hazards and provide probabilistic forecasts of coastal geomorphic change. The SERAP will expand on these existing projects and include the following tasks, which were initiated in summer 2009: * Regionally downscaled probabilistic climate-change projections * Integrated coastal assessment * Integrated terrestrial assessment * Multi-resolution assessment of potential climate change effects on biological resources: aquatic and hydrologic dynamics * Optimal conservation strategies to cope with climate change The SERAP seeks to formally integrate these tasks to aid conservation planning and design so that ecosystem management decisions can be optimized for providing desirable outcomes across a range of species and environments. The following chapters detail SERAP's efforts in providing a suite of regional climate, watershed, and landscape-change analyses and develop the interdisciplinary framework required for the biological planning phases of adaptive management and strategic conservation. The planning phase will include the identification of conservation alternatives, development of predictive models and decision support tools, and development of a template to address similar challenges and goals in other regions. The project teams will explore and develop ways to link the various ecological models arising from each component. The SERAP project team also will work closely with members of the LCCs and other partnerships throughout the life of the project to ensure that the objectives of the project meet resources mangers needs in the Southeast.

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