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At least 973 records · Page 54Linked to original sources
USGS2017

What can volunteer angler tagging data tell us about the status of the Giant Trevally (ulua aukea) Caranx ignobilis fishery in Hawaii: revisiting data collected during Hawaii’s Ulua and Papio Tagging Project 2000-2016

Giant Trevally (ulua aukea) Caranx ignobilis is one of the most highly prized and frequently targeted nearshore species. However, there is very little information on its current status in Hawaiian waters. This study uses mark-recapture data collected as part of recreational angler tagging program conducted by the Hawaii Department of Land and Natural Resources-Division of Aquatic Resources during 2000-2012. Mark-recapture data were used to estimate von Bertalanffy growth curve parameters and survivorship. Growth curves generated from the markrecapture data suggested that Giant Trevally from the main Hawaiian Islands may be growing faster and reach a smaller maximum size than individuals in the Northwest Hawaiian Islands, but there are a number of issues rendering this conclusion uncertain. The survivorship of Giant Trevally was positively associated with age, in part due to ontogenetic habitat shifts that result in older fish moving to offshore habitats where they are less vulnerable to anglers. When compared to stock assessments performed using commercial landings data and fisheries-independent visual surveys, the mark-recapture data produced similar estimates for the average length of exploited fish, a metric highly negatively correlated to fishing mortality. These results emphasize the need for additional information on the biology of Giant Trevally in Hawaiian waters and suggest that the data collected from this recreational angler tagging program may be useful to generate reliable estimates of mortality for stock assessment purposes.

Hawaii↗
USGS2024

Global assessment of aquatic Isoëtes species ecology

Isoëtes are iconic but understudied wetland plants, despite having suffered severe losses globally mainly because of alterations in their habitats. We therefore provide the first global ecological assessment of aquatic Isoëtes to identify their environmental requirements and to evaluate if taxonomically related species differ in their ecology. The assessment resulted in an extensive new database on aquatic Isoëtes , ecological niche analyses, and descriptive species accounts. We compiled a global database that includes all known environmental data collected from 1935 to 2023 regarding aquatic Isoëtes. We then evaluated the environmental drivers of 16 species using 2,179 global records. Additionally, we used hypervolume analysis to quantify the ecological niches of the two species with the greatest number of records, finding significant differences and evidence that Isoëtes echinospora occupies a wider ecological niche than Isoëtes lacustris . Fifty-nine species (30% of the c. 200 Isoëtes species known today) were categorised as aquatic and were mainly reported in the Americas and northern Europe. About 38% of the aquatic species are threatened with extinction or are endemic to a small region, according to the International Union for Conservation of Nature's Red List in 2023. Many species were determined to be sensitive to certain water physical and chemical factors, generally preferring oligotrophic conditions such as low total phosphorus, moderate total nitrogen, moderate to low pH, and low conductivity. This analysis includes ecological data in the assessment of rare/threatened aquatic plants globally. This new database and the ecological analyses completed defined the ecological requirements of several species and identified knowledge gaps, which can aid management actions and future research. This paper highlights ecological significance and environmental sensitivities of aquatic Isoëtes . The current level of knowledge is inadequate for a large proportion of known taxa. We affirm the extreme need to support global, collaborative initiatives on which to build future conservation strategies.

Freshwater Biology↗
USGS2013

Maintaining and restoring sustainable ecosystems in southern Nevada

Managers in southern Nevada are challenge with determining appropriate goals and objectives and developing viable approaches for maintaining and restoring sustainable ecosystems in a time of rapid socio-ecological and environmental change. Sustainable or "healthy" ecosystems supply clean air, water and habitat for a diverse array of plants and animals. As described in Chapter 1, sustainable ecosystems retain characteristic processes like hydrological flux and storage, geomorphic processes, biogeochemical cycling and storage, biological activity and productivity, and population regeneration and reproduction over the normal cycle of disturbance events (modified from Chapin and others 1996 and Christensen and others 1996). Ecological restoration of stressed or disturbed ecosystems in an integral part of managing for sustainable ecosystems. The Society of Ecological Restoration International (SERI) defines ecological restoration as the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed (SERI 2004). Many of the southern Nevada's ecosystems are being subjected to anthropogenic stressors that span global, regional, and local scales (Chapter 2)., and are crossing ecological thresholds to new alternative states (Chapter 4 and Chapter 5). These alternative states often represent novel communities with disturbance regimes that differ significantly from historic conditions. Past management and restoration goals often focused on returning ecosystems to pre-disturbance conditions (Harris and others 2006). This approach assumes stable or equilibrium conditions and ignores changes in ecosystems processes due to land uses, increases in CO 2 concentrations, and climate change. A more realistic approach is to base management and restoration goals on the current potential of an ecosystem to support a given set of ecological conditions, and on the likelihood of future change due to warming climate (Harris and others 2006). This approach requires understanding ecosystem resilience to anthropogenic disturbance and climate change, the alternative states that exist for ecosystems, and the factors that result in threshold crossing (Bestelmeyer and others 2009; Hobbs and Harris 2001; Stingham and others 2003; Whisemnant 1999). It also requires the ability to predict how climate is likely to influence ecosystems in the future (Harris and others 2006). This chapter addresses the restoration aspects of Sub-goal 1.3 in the SNAP Science Research Strategy which is to restore and sustain proper function of southern Nevada's watersheds and landscapes (able 1.3; Turner and others 2009). The effects of global, regional and local stresses on southern Nevada ecosystems are presented in Chapter 2. Here, we discuss appropriate objectives and develop guidelines for maintaining and restoring southern Nevada ecosystems. We then discuss the differences in ecological resilience to stress and disturbance and resistance to invasive species in southern Nevada ecosystems and describe restoration and management approaches for the different ecosystem types. We conclude with knowledge gaps and management implications.

Nevada↗
USGS2016

A morphological review of subspecies of the Asian box turtle, Cuora amboinensis (Testudines, Geomydidae)

The turtle Cuora amboinensis has an extensive distribution covering most of southern mainland Asia, Indonesia, and extending to the Philippine Islands. Unlike many species, C. amboinensis occurs on both sides of Wallace's Line separating Asian and Australian flora and fauna. Four subspecies are currently recognized; Cuora a . kamaroma (southern continental Asia, Java and the northern Philippines [introduced]), C. a . lineata (Kachin Province, Myanmar [Burma] and adjacent Yunnan Province, China), C. a . couro (Sumatra, Java, Sumbawa, and adjacent smaller Indonesian islands); and C. a . amboinensis (Moluccas, Sulawesi, Philippines). Five pattern and 33 morphological characters were examined for variation in 691 individuals from throughout the species' range. Our analyses suggest that only two presently recognized subspecies are valid: amboinensis and kamaroma . Neither couro nor lineata are supported by our analysis. We recommend that C. a . couro should be synonymized with the species C. amboinensis and C. a . lineata with the subspecies C. a . kamaroma .

Proceedings of the Biological Society of Washingto↗
USGS2016

Ecological requirements for pallid sturgeon reproduction and recruitment in the Missouri River—A synthesis of science, 2005 to 2012

This report is intended to synthesize the state of the scientific understanding of pallid sturgeon ecological requirements to provide recommendations for future science directions and context for Missouri River restoration and management decisions. Recruitment of pallid sturgeon has been low to non-existent throughout its range. Emerging understanding of the genetic structure of pallid sturgeon populations sets a broad framework for species and river management decisions, including decisions about managing the future genetic diversity of the species, but also decisions about where and what type of river restoration actions will be effective for subpopulations of this highly migratory species. Adult pallid sturgeon may migrate hundreds of kilometers (km) to spawn and their progeny may disperse even greater distances downstream as drifting free embryos. As a result of their complex life history pallid sturgeon naturally exploit a wide range of habitats during their life cycles. The construction of dams and reservoirs has fragmented habitats and may have shifted Missouri River subpopulations downstream. Research has not identified one primary biological or ecological constraint that appears to limit populations of the pallid sturgeon. With the present (2013) state of knowledge many life stages and life-stage transitions cannot be ruled out as contributing to recruitment failure. Biological opinions in 2000 (and amended in 2003) presented the dominant hypotheses for recruitment failure that existed at that time. Emphasis was on the role of the flow regime, specifically spring flow pulses (“spring rises”), to condition spawning substrate and cue reproductive aggregations and migrations, and on low flows and additional slow, shallow-water area to serve as rearing habitat for age-0 to juvenile pallid sturgeon. Studies on spawning habitat dynamics have documented that habitat patches selected for spawning by fish in the Lower Missouri River (Missouri River downstream from Gavins Point Dam to the confluence with the Mississippi River) are dominantly on outside, revetted bends in the deepest, fastest, and most turbulent water. Studies in more natural habitat on the Yellowstone River have documented spawning in convergent flow in the middle of the channel on discrete patches of gravel within a sand-dominated channel, an arrangement that may be more effective in attracting aggregations of reproductive fish compared to the nearly continuous revetment on the Lower Missouri River. Pallid sturgeon spawn in the spring and early summer during periods of increasing day length. Water temperature consistently exerts a threshold effect for spawning at 16–18 °C. In addition, the role of water temperature is indicated by pauses and reversals in upstream migrations that have been associated with cold weather fronts that create a transient decrease in water temperature. From 2005 to 2012 on the Lower Missouri River, no obvious relations between flow pulses and fish movements and spawning behaviors have been apparent. However, pallid sturgeon tracking at the Upper Missouri–Yellowstone confluence indicates that in most years, most telemetered pallid sturgeon migrate out of the Missouri River and into the Yellowstone River in the June–July timeframe in association with the spring pulse. This pattern was disrupted in 2011 when a high flow pulse with warm temperatures and high turbidity emanated from the Milk River, followed by record releases from Fort Peck Dam, and 36–39 percent of the telemetered population migrated up the Upper Missouri. This result supports the hypothesis that sufficiently large flow pulses may trigger migration and aggregation but it is not clear that functional pulses are within reservoir management authorities. Notably, a pallid sturgeon free embryo was captured on the Upper Missouri River in 2011 and another single, genetically confirmed embryo was captured on the Yellowstone River in 2012. Research on free-embryo drift has indicated the potential for hundreds of miles of downstream dispersal. Lack of distance to accommodate the extended downstream dispersal period of free embryos on the Upper Missouri and Yellowstone Rivers is the predominant hypothesis for recruitment failure in the upper basin. Long drift distances in the Lower Missouri River may be responsible for shifting Lower Missouri River sub-populations further into the Middle Mississippi River. Physical understanding of drift processes indicates that mean velocities could be slowed through decreased discharges or increased channel hydraulic radius (width and topographic diversity) to reduce free-embryo dispersal distances. In addition, the probability that free embryos are transported into and retained in channel-margin habitats is theoretically amenable to channel re-engineering that would increase cross-channel secondary currents in bends or channel expansions. Considerable uncertainty persists, however, about whether extended drift of Lower Missouri River larvae is responsible for recruitment failure. If drift distance is limiting, it is important to discern whether it would be advisable to retain larvae within the Missouri River, and where along the river restoration projects should be placed to optimize survival and growth of age-0 and juvenile sturgeon. Longitudinal differences in female pallid sturgeon fecundity lend support to the hypothesis that recruitment failure may be due, in part, to fish having insufficient nutrition to produce the numbers of gametes needed for the population to grow, perhaps because of simultaneous declines in prey-fish populations and their habitats. Establishing a chain of causality from habitat decline, to prey-fish populations, to sturgeon diets, to sturgeon fecundity, and to pallid sturgeon population growth presents a considerable scientific challenge. In addition to the dominant hypotheses relating pallid sturgeon populations to changes in flow regime and channel morphology, other factors have been identified that might be sources of stress and contribute to recruitment failure. Among these are water quality and contaminants. Ambient water-quality monitoring on the Missouri River has demonstrated summer episodes when dissolved oxygen dips below 5 milligrams per liter, a threshold that may be stressful especially to age-0 and juvenile sturgeon. Documented cases of intersex in shovelnose and pallid sturgeon indicate that agricultural and municipal sources of endocrine disrupting chemicals also may have a role in pallid sturgeon recruitment failure. Scientific understanding of the ecological requirements of pallid sturgeon has increased almost exponentially in the last two decades, and efforts are now turning from understanding fundamental biology of the species to quantifying how population dynamics relate to potential management actions. Progress in developing the science needed to inform management actions on the Missouri River may benefit from continuation of monitoring of reproductive cycles, reproductive movements, growth, and survival of telemetry tagged adults, increased emphasis on focused, complementary field and laboratory studies of factors influencing early life history, implementation of studies to resolve the role of food limitations in growth, survival, and reproductive condition, and implementation of studies designed specifically to parameterize models linking management to populations.

Missouri River↗
USGS2025

The functional traits behind fish rarity in an impounded river basin

Reservoirs alter flows and aquatic habitats, reordering rarity patterns of reservoir ichthyofauna by allowing certain fish traits to flourish while filtering others. We reviewed the composition of fish species in an impounded river basin (Tennessee River, USA) to identify traits that influence rarity. We delineate levels of rarity based on the number of occupied reservoirs and species distribution, compare traits across rarity levels, and pinpoint traits that influence species rarity inside reservoirs. Four rarity levels were designated to 212 fish species: absent from the reservoir, rare and restricted within the basin, rare and spread throughout the basin, and common throughout the basin. Common species had the most distinctive traits, suggesting highly filtered species. They exhibited higher fecundity, longevity, piscivory, potamodromy, and association with large woody debris, vegetation, slow current, and lacustrine habitats. Rare and spread and rare and restricted species were separated by a few macrohabitat traits, with the former tending to be more lowland, slow current, large river, and lacustrine-oriented whereas the latter more creek and lotic oriented. Only age at maturity, longevity, fecundity, and potamodromy—all of which were lower in absent species—separated the absent from the rare and restricted. About half of rare and restricted species were already rare and restricted pre-impoundment; the rest had wider distributions pre-impoundment denoting species vulnerable in reservoirs and needing conservation to prevent local extinctions. Signals gleaned from species traits and rarity analysis indicate that conservation of rare species may need to focus on enhancements to selected reservoir habitats and to basin-wide connectivity.

Alabama, Georgia, Kentucky, Tennessee↗
USGS2005

Leaf litter breakdown, microbial respiration and shredder production in metal-polluted streams

1. If species disproportionately influence ecosystem functioning and also differ in their sensitivities to environmental conditions, the selective removal of species by anthropogenic stressors may lead to strong effects on ecosystem processes. We evaluated whether these circumstances held for several Colorado, U.S.A. streams stressed by Zn. 2. Benthic invertebrates and chemistry were sampled in five second-third order streams for 1 year. Study streams differed in dissolved metal concentrations, but were otherwise similar in chemical and physical characteristics. Secondary production of leaf-shredding insects was estimated using the increment summation and size-frequency methods. Leaf litter breakdown rates were estimated by retrieving litter-bags over a 171 day period. Microbial activity on leaf litter was measured in the laboratory using changes in oxygen concentration over a 48 h incubation period. 3. Dissolved Zn concentrations varied eightfold among two reference and three polluted streams. Total secondary production of shredders was negatively associated with metal contamination. Secondary production in reference streams was dominated by Taenionema pallidum. Results of previous studies and the current investigation demonstrate that this shredder is highly sensitive to metals in Colorado headwater streams. Leaf litter breakdown rates were similar between reference streams and declined significantly in the polluted streams. Microbial respiration at the most contaminated site was significantly lower than at reference sites. 4. Our results supported the hypothesis that some shredder species contribute disproportionately to leaf litter breakdown. Furthermore, the functionally dominant taxon was also the most sensitive to metal contamination. We conclude that leaf litter breakdown in our study streams lacked functional redundancy and was therefore highly sensitive to contaminant-induced alterations in community structure. We argue for the necessity of simultaneously measuring community structure and ecosystem function in anthropogenically stressed ecosystems.

Freshwater Biology↗
USGS2012

A brief history and summary of the effects of river engineering and dams on the Mississippi River system and delta

The U.S. Geological Survey Forecast Mekong project is providing technical assistance and information to aid management decisions and build science capacity of institutions in the Mekong River Basin. A component of this effort is to produce a synthesis of the effects of dams and other engineering structures on large-river hydrology, sediment transport, geomorphology, ecology, water quality, and deltaic systems. The Mississippi River Basin (MRB) of the United States was used as the backdrop and context for this synthesis because it is a continental scale river system with a total annual water discharge proportional to the Mekong River, has been highly engineered over the past two centuries, and the effects of engineering have been widely studied and documented by scientists and engineers. The MRB is controlled and regulated by dams and river-engineering structures. These modifications have resulted in multiple benefits including navigation, flood control, hydropower, bank stabilization, and recreation. Dams and other river-engineering structures in the MRB have afforded the United States substantial socioeconomic benefits; however, these benefits also have transformed the hydrologic, sediment transport, geomorphic, water-quality, and ecologic characteristics of the river and its delta. Large dams on the middle Missouri River have substantially reduced the magnitude of peak floods, increased base discharges, and reduced the overall variability of intraannual discharges. The extensive system of levees and wing dikes throughout the MRB, although providing protection from intermediate magnitude floods, have reduced overall channel capacity and increased flood stage by up to 4 meters for higher magnitude floods. Prior to major river engineering, the estimated average annual sediment yield of the Mississippi River Basin was approximately 400 million metric tons. The construction of large main-channel reservoirs on the Missouri and Arkansas Rivers, sedimentation in dike fields, and protection of channel banks by revetments throughout the basin, have reduced the overall sediment yield of the MRB by more than 60 percent. The primary alterations to channel morphology by dams and other engineering projects have been (1) channel simplification and reduced dynamism; (2) lowering of channel-bed elevation; and (3) disconnection of the river channel from the flood plain, except during extreme flood events. Freshwater discharge from the Mississippi River and its associated sediment and nutrient loads strongly influence the physical and biological components in the northern Gulf of Mexico. Ninety percent of the nitrogen load reaching the Gulf of Mexico is from nonpoint sources with about 60 percent coming from fertilizer and mineralized soil nitrogen. Much of the phosphorus is from animal manure from pasture and rangelands followed by fertilizer applied to corn and soybeans. Increased nutrient enrichment in the northern Gulf of Mexico has resulted in the degradation of water quality as more phytoplankton grow, which increases turbidity and depletes oxygen in the lower depths creating what is known as the "dead zone." In 2002, the dead zone was 22,000 square kilometers (km2), an area similar to the size of the State of Massachusetts. Changes in the flow regime from engineered structures have had direct and indirect effects on the fish communities. The navigation pools in the upper Mississippi River have aged, and these overwintering habitats, which were created when the pools filled, have declined as sedimentation reduces water depth. Reproduction of paddlefish may have been adversely affected by dams, which impede access to suitable spawning habitats. Fishes that inhabit swift-current habitats in the unimpounded lower Mississippi River have not declined as much as in the upper Mississippi River. The decline of the pallid sturgeon may be attributable to channelization of the Missouri River above St. Louis, Missouri. The Missouri River supports a rich fish community and remains relatively intact. Nevertheless, the widespread and long history of human intervention in river discharge has contributed to the declines of about 25 percent of the species. The Mississippi River Delta Plain is built from six delta complexes composed of a massive area of coastal wetlands that support the largest commercial fishery in the conterminous United States. Since the early 20th century, approximately 4,900 km2 of coastal lands have been lost in Louisiana. One of the primary mechanisms of wetland loss on the Plaquemines-Balize complex is believed to be the disconnection of the river distributary network from the delta plain by the massive system of levees on the delta top, which prevent overbank flooding and replenishment of the delta top by sediment and nutrient deliveries. Efforts by Federal and State agencies to conserve and restore the Mississippi River Delta Plain began over three decades ago and have accelerated over the past decade. Regardless of these efforts, however, land losses are expected to continue because the reduced upstream sediment supplies are not sufficient to keep up with the projected depositional space being created by the combined forces of delta plain subsidence and global sea-level rise.

Alabama;Alberta;Arkansas;Colorado;Georgia;Illinois↗
USGS2017

Fish Bioenergetics 4.0: An R-based modeling application

Bioenergetics modeling is a widely used tool in fisheries management and research. Although popular, currently available software (i.e., Fish Bioenergetics 3.0) has not been updated in over 20 years and is incompatible with newer operating systems (i.e., 64‐bit). Moreover, since the release of Fish Bioenergetics 3.0 in 1997, the number of published bioenergetics models has increased appreciably from 56 to 105 models representing 73 species. In this article, we provide an overview of Fish Bioenergetics 4.0 (FB4), a newly developed modeling application that consists of a graphical user interface (Shiny by RStudio) combined with a modeling package used in the R computing environment. While including the same capabilities as previous versions, Fish Bioenergetics 4.0 allows for timely updates and bug fixes and can be continuously improved based on feedback from users. In addition, users can add new or modified parameter sets for additional species and formulate and incorporate modifications such as habitat‐dependent functions (e.g., dissolved oxygen, salinity) that are not part of the default package. We hope that advances in the new modeling platform will attract a broad range of users while facilitating continued application of bioenergetics modeling to a wide spectrum of questions in fish biology, ecology, and management.

Fisheries Magazine↗
USGS1999

Time course of salinity adaptation a strongly euryhaline estuarine teleost, Fundulus Heteroclitus: A multivariable approach

Freshwater-adapted killifish ( Fundulus heteroclitus ) were transferred directly from soft fresh water to full-strength sea water for periods of 1 h, 3 h, 8 h and 1, 2, 7, 14 and 30 days. Controls were transferred to fresh water for 24 h. Measured variables included: blood [Na + ], osmolality, glucose and cortisol levels, basal and stimulated rates of ion transport and permeability of in vitro opercular epithelium, gill Na + /K + -ATPase and citrate synthase activity and chloride cell ultrastructure. These data were compared with previously published killifish cystic fibrosis transmembrane conductance regulator (kfCFTR) expression in the gills measured over a similar time course. Plasma cortisol levels peaked at 1 h, coincident with a rise in plasma [Na + ]. At 8 h after transfer to sea water, a time at which previous work has shown kfCFTR expression to be elevated, blood osmolality and [Na + ] were high, and cortisol levels and opercular membrane short-circuit current ( I sc ; a measure of Cl − secretion rate) were low. The 24 h group, which showed the highest level of kfCFTR expression, had the highest plasma [Na + ] and osmolality, elevated plasma cortisol levels, significantly lower opercular membrane resistance, an increased opercular membrane ion secretion rate and collapsed tubule inclusions in mitochondria-rich cells, but no change in gill Na + /K + -ATPase and citrate synthase activity or plasma glucose levels. Apparently, killifish have a rapid (<1 h) cortisol response to salinity coupled to subsequent (8–48 h) expression of kfCFTR anion channel proteins in existing mitochondria-rich cells that convert transport from ion uptake to ion secretion.

Journal of Experimental Biology↗
USGS2001

Population persistence in Florida torreya: Comparing modeled projections of a declining coniferous tree

The Florida torreya ( Torreya taxifolia ) is a coniferous tree endemic to a 35-km stretch of bluffs and ravines along the east side of the Apalachicola River in northern Florida and southern Georgia. This formerly locally abundant tree has declined as a result of disease during the 1950s and is on the U.S. endangered species list. With no seed production in the wild, this species is headed toward extinction. We conducted a survey on roughly 200 trees from 1988 to 1996 and used these data to estimate the likelihood of population persistence during the next several decades. We compared a stage-class transition matrix model ( RAMAS) and an individual-based stochastic model ( TORSIM) of growth and mortality to project future populations. Given the current lack of seed production in the wild, all models predict extinction. The question of concern is the imminence of this predicted extinction. Differing predicted times to extinction would suggest different immediate management recommendations. Both models predicted an over 90% likelihood of persistence during the next 50 years. Predictions differed in that the transition matrix model was less optimistic than the individual-based model regarding persistence. Model sensitivity analysis showed that the results were robust to significant decreases in growth and sprouting probabilities. Submodels identified different persistence likelihoods in different populations. Nonetheless, unless management of the population can facilitate maturation and seed production, extinction of this species in the wild is inevitable.

Conservation Biology↗
USGS2008

Examining differences between recovered and declining endangered species

Between 1973 and 1999, 43 species in the United States were reclassified from endangered to threatened or removed entirely from the Endangered Species List. Of these, 23 were identified as recovered. In 1999 the U.S. Fish and Wildlife Service ( USFWS) published a list of 33 additional species for possible reclassification and/or delisting. We initiated this study to examine why some endangered species recover but others continue to decline and to identify differences in management activities between these two groups. We defined recovered/recovering species as previously recovered species and the additional recovered/recovering species listed by the USFWS. We defined declining species as those identified as declining in the most recent USFWS Report to Congress. Information on recovered/recovering and declining species was gathered from relevant literature, recovery plans, U.S. Federal Register documents, and individuals responsible for the recovery management of each species. We used this information to examine (1) the percentage of current and historic range covered by management activities; (2) threats affecting the species; (3) population sizes at the time of listing; (4) current versus historic range size; and (5) percentage of recovery management objectives completed. Although few statistical analyses provided significant results, those that did suggest the following differences between recovered/recovering and declining species: (1) recovered/recovering species face threats that are easier to address; (2) recovered/recovering species occupy a greater percentage of their historic range; and (3) recovered/recovering species have a greater percentage of their recovery management objectives completed. Those species with threats easier to address and that occupy a greater percentage of their historic range are recovered/recovering. In contrast, declining species face threats more difficult to address and occupy significantly less of their historic range. If this remains true, future species recovery may require more time and resources.

Conservation Biology↗
USGS2007

Southwest Exotic Mapping Program 2007: Occurrence summary and maps of select invasive, non-native plants in Arizona

An important aspect of management of invasive, non-native plants (invasive plants) is information on the type, location, and magnitude of infestations. Regional development of this information requires an integrated program of data collection, management, and delivery. The Southwest Exotic Plant Mapping Program (SWEMP), coordinated through the U.S. Geological Survey’s Southwest Biological Science Center, annually compiles occurrence records for infestations of invasive plants. Operating since 1998, the SWEMP team has accepted occurrence records contributed voluntarily by federal, tribal, state, and private collaborators and has compiled these contributions accumulatively with previous versions of SWEMP. The SWEMP 2007 regional database update, SWEMP07, contains 62,000 records for 221 plant species with records dating as far back as 1911 and up to December, 2006. Records include invasive plants in Arizona, eastern California, Colorado, New Mexico, and Utah. SWEMP07 is available through the Southwest Exotic Plant Information Clearinghouse ( http://sbsc.wr.usgs.gov/research/projects/swepic/swepic.asp , click SWEMP). Not all invasive plants are non-native and not all invasive plants are even invasive. The Arizona Invasive Species Advisory Council (2006) defined an invasive species as “a species that is (1) non-native to the ecosystem under consideration and, (2) whose introduction causes or is likely to cause economic or environmental harm, or harm to human health”. SWEMP uses the U.S. Department of Agriculture PLANTS database ( http://plants.usda.gov/ ) to determine if a plant is native or not to Arizona. As SWEMP does not independently assess the current or potential impact of invasive plants, we include most non-native plant records contributed. We have not included agricultural crops that are non-native, for example apples, oranges, etc. In this open-file-report, we use the SWEMP07 update to summarize the occurrence of invasive plants in Arizona and present distribution maps for a select invasive plants in Arizona. We use the word occurrence purposefully instead of the word distribution. The SWEMP07 database only provides an estimate of the actual distribution of invasive plants in Arizona. The information provided is a first approximation of the state-wide extent of invasive plant distribution.

Open-File Report↗
USGS2014

Spatial distribution of loggerhead turtle ( Caretta caretta ) emergences along a highly dynamic beach in the northern Gulf of Mexico

As coastlines change due to sea level rise and an increasing human presence, understanding how species, such as marine turtles, respond to alterations in habitat is necessary for proper management and conservation. Survey data from a major nesting beach in the northern Gulf of Mexico, where a revetment was installed, was used to assess spatial distribution of loggerhead emergences. Through use of Quadrat analysis and piecewise linear regression with breakpoint, we present evidence to suggest that nest site selection in loggerheads is determined in the nearshore environment, and by characteristics such as wave height, alongshore currents, depth and patterns of erosion and accretion. Areas of relatively dense nesting were found in areas with relatively strong alongshore currents, relatively small waves, a steep offshore slope and the largest historical rates of erosion. Areas of relatively dense nesting also corresponded to areas of low nesting success. Both nesting and non-nesting emergences were clustered immediately adjacent to the revetment and at other eroding sites along the beach. These results suggest that alterations to the nearshore environment from activities such as construction of a jetty, dredging or installation of pilings, may impact sea turtle nest distribution alongshore. We also show that piecewise linear regression with breakpoint is a technique that can be used with geomorphological and oceanographic data to predict locations of nest clumping and may be useful for managers at other nesting beaches.

Florida↗
USGS2017

Conservation, biodiversity and infectious disease: scientific evidence and policy implications

Habitat destruction and infectious disease are dual threats to nature and people. The potential to simultaneously advance conservation and human health has attracted considerable scientific and popular interest; in particular, many authors have justified conservation action by pointing out potential public health benefits . One major focus of this debate—that biodiversity conservation often decreases infectious disease transmission via the dilution effect—remains contentious. Studies that test for a dilution effect often find a negative association between a diversity metric and a disease risk metric, but how such associations should inform conservation policy remains unclear for several reasons. For one, diversity and infection risk have many definitions, making it possible to identify measures that conform to expectations. Furthermore, the premise that habitat destruction consistently reduces biodiversity is in question, and disturbance or conservation can affect disease in many ways other than through biodiversity change. To date, few studies have examined the broader set of mechanisms by which anthropogenic disturbance or conservation might increase or decrease infectious disease risk to human populations. Due to interconnections between biodiversity change, economics and human behaviour, moving from ecological theory to policy action requires understanding how social and economic factors affect conservation. This Theme Issue arose from a meeting aimed at synthesizing current theory and data on ‘biodiversity, conservation and infectious disease’ (4–6 May 2015). Ecologists, evolutionary biologists, economists, epidemiologists, veterinary scientists, public health professionals, and conservation biologists from around the world discussed the latest research on the ecological and socio-economic links between conservation, biodiversity and infectious disease, and the open questions and controversies in these areas. By combining ecological understanding with insights from the social and economic sciences, the papers in this Theme Issue address the complex relationships, patterns and ecological mechanisms that influence conservation, infectious disease, and the policy options available to protect nature and human health.

Philosophical Transactions of the Royal Society B:↗
USGS2016

Toward a quantitative and empirical dissolved organic carbon budget for the Gulf of Maine, a semienclosed shelf sea

A time series of organic carbon export from Gulf of Maine (GoM) watersheds was compared to a time series of biological, chemical, bio-optical, and hydrographic properties, measured across the GoM between Yarmouth, NS, Canada, and Portland, ME, U.S. Optical proxies were used to quantify the dissolved organic carbon (DOC) and particulate organic carbon in the GoM. The Load Estimator regression model applied to river discharge data demonstrated that riverine DOC export (and its decadal variance) has increased over the last 80 years. Several extraordinarily wet years (2006–2010) resulted in a massive pulse of chromophoric dissolved organic matter (CDOM; proxy for DOC) into the western GoM along with unidentified optically scattering material (<0.2 μm diameter). A survey of DOC in the GoM and Scotian Shelf showed the strong influence of the Gulf of Saint Lawrence on the DOC that enters the GoM. A deep plume of CDOM-rich water was observed near the coast of Maine which decreased in concentration eastward. The Forel-Ule color scale was derived and compared to the same measurements made in 1912–1913 by Henry Bigelow. Results show that the GoM has yellowed in the last century, particularly in the region of the extension of the Eastern Maine Coastal Current. Time lags between DOC discharge and its appearance in the GoM increased with distance from the river mouths. Algae were also a significant source of DOC but not CDOM. Gulf-wide algal primary production has decreased. Increases in precipitation and DOC discharge to the GoM are predicted over the next century.

Gulf of Maine↗
USGS2020

Assessing the vulnerability of military installations in the coterminous United States to potential biome shifts resulting from rapid climate change

Climate change impacts to Department of Defense (DoD) installations will challenge future military mission and natural resource stewardship efforts by increasing vulnerability to flooding, drought, altered fire regimes, invasive species, etc. We developed biome classifications based on current climate for the coterminous United States using the Holdridge Life Zone system to assess potential change on DoD lands. We validated classifications using comparisons to existing ecoregional classifications, the distribution of major forest types and tree species in eastern North America. We projected future life zones for mid- and late century time periods under three greenhouse gas emission scenarios (low - B1, moderate - A1B and high - A2) using an ensemble of global climate models. To assess vulnerability of installations (n = 529), we analyzed biome shifts using spatial cluster analysis to characterize interregional variation and identified representative installations for subsequent landscape-level analyses. Although mean annual temperatures are expected to increase, installations located in the Northeast, Lake States and western Great Plains are likely to experience the largest proportional increases in temperature relative to historical conditions. Accordingly, forest and grassland communities at these installations managed to support a wide range of military training and environmental objectives may be adversely affected by altered disturbance regimes, heat and moisture stress. However, precipitation is projected to increase in the Northeast and Lake States mitigating some effects of increased atmospheric temperatures on biological communities. Given the uncertain response to climate change in the coming decades in different ecoregions, additional environmental and stewardship attributes are needed within a decision support framework to understand vulnerabilities and provide appropriate responses.

Arizona, Arkansas, California, Colorado, Connectic↗
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↗