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At least 289 records · Page 16Linked to original sources

USGS1999

GIXAFS study of Fe3+ sorption and precipitation on natural quartz surfaces

Grazing-incidence EXAFS has been used to characterize the structure of Fe 3+ sorbed onto natural single crystal quartz surfaces. Fe 3+ sorption at ca. 5% monolayer coverage on a natural crystal allowed to equilibrate in air resulted in formation of hematite nuclei with strong texturing on r-and m-planes. EXAFS calculations suggests that both O and Fe backscattering is necessary to yield acceptable structural models, that about 50% of the sorbed iron resides in nuclei, and that the approximate dimensions of the nuclei can be estimated via Feff 7.0 calculations of various nuclei sizes and shapes.

Journal of Synchrotron Radiation↗

USGS2017

Effects of host species and environment on the skin microbiome of Plethodontid salamanders

The amphibian skin microbiome is recognized for its role in defence against pathogens, including the deadly fungal pathogen Batrachochytrium dendrobatidis (Bd). Yet, we have little understanding of evolutionary and ecological processes that structure these communities, especially for salamanders and closely related species. We investigated patterns in the distribution of bacterial communities on Plethodon salamander skin across host species and environments. Quantifying salamander skin microbiome structure contributes to our understanding of how host-associated bacteria are distributed across the landscape, among host species, and their putative relationship with disease. We characterized skin microbiome structure (alpha-diversity, beta-diversity and bacterial operational taxonomic unit [OTU] abundances) using 16S rRNA gene sequencing for co-occurring Plethodon salamander species (35 Plethodon cinereus , 17 Plethodon glutinosus , 10 Plethodon cylindraceus ) at three localities to differentiate the effects of host species from environmental factors on the microbiome. We sampled the microbiome of P. cinereus along an elevational gradient ( n = 50, 700–1,000 m a.s.l.) at one locality to determine whether elevation predicts microbiome structure. Finally, we quantified prevalence and abundance of putatively anti-Bd bacteria to determine if Bd-inhibitory bacteria are dominant microbiome members. Co-occurring salamanders had similar microbiome structure, but among sites salamanders had dissimilar microbiome structure for beta-diversity and abundance of 28 bacterial OTUs. We found that alpha-diversity increased with elevation, beta-diversity and the abundance of 17 bacterial OTUs changed with elevation (16 OTUs decreasing, 1 OTU increasing). We detected 11 putatively anti-Bd bacterial OTUs that were present on 90% of salamanders and made up an average relative abundance of 83% ( SD ± 8.5) per salamander. All salamanders tested negative for Bd. We conclude that environment is more influential in shaping skin microbiome structure than host differences in these congeneric species, and suggest that environmental characteristics that covary with elevation influence microbiome structure. High prevalence and abundance of anti-Bd bacteria may contribute to low Bd levels in these populations of Plethodon salamanders.

Journal of Animal Ecology↗

USGS2020

A test of the Niche Variation Hypothesis in a ruminant herbivore

Despite the shared prediction that the width of a population's dietary niche expands as food becomes limiting, the Niche Variation Hypothesis (NVH) and Optimal Foraging Theory (OFT) offer contrasting views about how individuals alter diet selection when food is limited. Classical OFT predicts that dietary preferences do not change as food becomes limiting, so individuals expand their diets as they compensate for a lack of preferred foods. In contrast, the NVH predicts that among-individual variation in cognition, physiology or morphology create functional trade-offs in foraging efficiency, thereby causing individuals to specialize on different subsets of food as food becomes limiting. To evaluate (a) the predictions of the NVH and OFT and (b) evidence for physiological and cognitive-based functional trade-offs, we used DNA microsatellites and metabarcoding to quantify the diet, microbiome and genetic relatedness (a proxy for social learning) of 218 moose Alces alces across six populations that varied in their degree of food limitation. Consistent with both the NVH and OFT, dietary niche breadth increased with food limitation. Increased diet breadth of individuals—rather than increased diet specialization—was strongly correlated with both food limitation and dietary niche breadth of populations, indicating that moose foraged in accordance with OFT. Diets were not constrained by inheritance of the microbiome or inheritance of diet selection, offering support for the little-tested hypothesis that functional trade-offs in food use (or lack thereof) determine whether populations adhere to the predictions of the NVH or OFT. Our results indicate that both the absence of strong functional trade-offs and the digestive physiology of ruminants provide contexts under which populations should forage in accordance with OFT rather than the NVH. Also, because dietary niche width increased with increased food limitation, OFT and the NVH provide theoretical support for the notion that plant–herbivore interaction networks are plastic rather than static, which has important implications for understanding interspecific niche partitioning. Lastly, because population-level dietary niche breadth and calf recruitment are correlated, and because calf recruitment can be a proxy for food limitation, our work demonstrates how diet data can be employed to understand a populations' proximity to carrying capacity.

Colorado, Utah, Wyoming↗

USGS2021

Age-related reproductive performance of the Adélie penguin, a long-lived seabird exhibiting similar outcomes regardless of individual life-history strategy

Age-related variation in reproductive performance in long-lived iteroparous vertebrate species is common, with performance being influenced by within-individual processes, such as improvement and senescence, in combination with among-individual processes, such as selective appearance and disappearance. Few studies of age-related reproductive performance have compared the role of these drivers within a metapopulation, subject to varying degrees of resource competition. We accounted for within- and among-individual changes among known-aged Adélie penguins Pygoscelis adeliae during 17 years (1997-2013), at three clustered colonies of disparate size, to understand patterns in age-related reproductive success during early and late adulthood. Age at first reproduction (AFR) was lowest, and number of breeding attempts highest, at the largest colony. Regardless of AFR, success improved with early post-recruitment experience. For both oldest and youngest recruitment groups, peak performance occurred at the end of their reproductive life span indicating a possible cost of reproduction. Intermediate recruitment groups reached peak performance in their mid-reproductive life span and with intermediate breeding experience, before decreasing. Breeding success was lowest for the initial breeding attempt regardless of AFR, but we observed subsequent variation relative to recruitment age. Gaining experience by delaying recruitment positively influenced reproductive performance early in the reproductive life span and was most evident for the youngest breeders. Oldest recruits had the highest initial and peak breeding success. Differences in AFR resulted in trade-offs in reproductive life span or timing of senescence but not in the overall number of breeding attempts. Patterns differed as a function of colony size, and thus competition for resources. Early life improvement in performance at the larger colonies was primarily due to within-individual factors and at the largest colony, AFR. Regardless of colony size late-life performance was positively related to the age at last reproduction, indicating selective disappearance of lower performing individuals. These results highlight that different life-history strategies were equally successful, indicating that individuals can overcome potential trade-offs associated with early- and late-life performance. These results have important implications for understanding the evolution of life-history strategies responsible for driving population change.

Beaufort Island ,Ross Island↗

USGS2022

Behavioural adjustments in the social associations of a precocial shorebird mediate the costs and benefits of grouping decisions

Animals weigh multiple costs and benefits when making grouping decisions. The cost-avoidance grouping framework proposes that group density, information quality and risk affect an individual’s preference for con or heterospecific groups. However, this assumes the cost–benefit balance of a particular grouping is constant spatiotemporally, which may not always be true. Investigating how spatiotemporal context influences grouping choices is therefore key to understanding how animals contend with changing conditions. Changes in body size during development lead to variable conditions for individuals over short time-scales that can influence their ecological interactions. Hudsonian godwits Limosa haemastica , for instance, form a protective nesting association with a major predator of young godwit chicks, colonial short-billed gulls Larus brachyrhynchus . Godwit broods may avoid areas of higher gull densities when chicks are susceptible to gull predation but likely experience higher risk from alternative predators as a result. Associating with conspecifics could allow godwits to buffer these costs but requires enough other broods with whom to group. To determine how age-dependent predation risk and conspecific density influence godwit grouping behaviours, we first quantified the time-dependent effects of con- and heterospecific interactions on the mortality risk for godwit chicks throughout development. We then determined how godwit density and chick age affected their associations with con- and heterospecific. We found that younger godwit chicks' survival improved with closer association with conspecifics, earlier hatch dates and lower gull densities, whereas older chicks survived better with earlier hatch dates, though this effect was less clear. Concomitantly, godwit broods avoided gulls early in development and when godwit densities were high but maintained loose associations with conspecifics throughout development. We identified how individuals can optimally shift with whom they group according to risks that vary spatially and temporally. Investigating the effects of a species' ecological interactions across spatiotemporal contexts in this way can shed light on how animals adjust their associations according to the costs and benefits of each association.

Journal of Animal Ecology↗

USGS2022

Using piecewise regression to identify biological phenomena in biotelemetry datasets

1. Technological advances in the field of animal tracking have greatly expanded the potential to remotely monitor animals, opening the door to exploring how animals shift their behavior over time or respond to external stimuli. A wide variety of animal-borne sensors can provide information on an animal’s location, movement characteristics, external environmental conditions, and internal physiological status. 2. Here, we demonstrate how piecewise regression can be used to identify the presence and timing of potential shifts in a variety of biological responses using GPS telemetry and other biologging data streams. Different biological latent states can be inferred by partitioning a time-series into multiple segments based on changes in modeled responses (e.g., their mean, variance, trend, degree of autocorrelation) and specifying a unique model structure for each interval. 3. We provide six example applications highlighting a variety of taxonomic species, data streams, timescales and biological phenomena. These examples include a short-term behavioural response (flee and return) by a trumpeter swan Cygnus buccinator following a GPS collar deployment; remote identification of parturition based on movements by a pregnant moose Alces alces ; a physiological response (spike in heart-rate) in a black bear Ursus americanus to a stressful stimulus(presence of a drone); a mortality event of a trumpeter swan signalled by changes in collar temperature and overall dynamic body acceleration; an unsupervised method for identifying the onset, return, duration and staging use of sandhill crane Antigone canadensis migration; and estimation of the transition between incubation and brood-rearing (i.e. hatching) for a breeding trumpeter swan. 4. We implement analyses using the MCP package in R, which provides functionality for specifying and fitting a wide variety of user-defined model structures in a Bayesian framework and methods for assessing and comparing models using information criteria and cross-validation measures.

Journal of Animal Ecology↗

USGS2024

A ‘how-to’ guide for estimating animal diel activity using hierarchical models

Animal diel activity patterns can aid understanding of (a) how species behaviourally adapt to anthropogenic and natural disturbances, (b) mechanisms of species co-existence through temporal partitioning, and (c) community or ecosystem effects of diel activity shifts. Activity patterns often vary spatially, a feature ignored by the kernel density estimators (KDEs) currently used for estimating diel activity. Ignoring this source of heterogeneity may lead to biased estimates of uncertainty and misleading conclusions regarding the drivers of diel activity. Thus, there is a need for more flexible statistical approaches for estimating activity patterns and testing hypotheses regarding their biotic and abiotic drivers. We illustrate how trigonometric terms and cyclic cubic splines combined with hierarchical models can provide a valuable alternative to KDEs. Like KDEs, these models accommodate circular data, but they can also account for site-to-site and other sources of variability, correlation amongst repeated measures, and variable sampling effort. They can also more readily quantify and test hypotheses related to the effects of covariates on activity patterns. Through empirical case studies, we illustrate how hierarchical models can quantify changes in activity levels due to seasonality and in response to biotic and abiotic factors (e.g. anthropogenic stressors and co-occurrence). We also describe frequentist and Bayesian approaches for quantifying site-specific (conditional) and population-averaged (marginal) activity patterns. We provide guidelines and tutorials with detailed step-by-step instructions for fitting and interpreting hierarchical models applied to time-stamped data, such as those recorded by camera traps and audio recorders. We conclude that this approach offers a viable, flexible, and effective alternative to KDEs when modelling animal activity patterns.

Journal of Animal Ecology↗

USGS2015

Spatial occupancy models for predicting metapopulation dynamics and viability following reintroduction

The reintroduction of a species into its historic range is a critical component of conservation programmes designed to restore extirpated metapopulations. However, many reintroduction efforts fail, and the lack of rigorous monitoring programmes and statistical models have prevented a general understanding of the factors affecting metapopulation viability following reintroduction. Spatially explicit metapopulation theory provides the basis for understanding the dynamics of fragmented populations linked by dispersal, but the theory has rarely been used to guide reintroduction programmes because most spatial metapopulation models require presence–absence data from every site in the network, and they do not allow for observation error such as imperfect detection. We develop a spatial occupancy model that relaxes these restrictive assumptions and allows for inference about metapopulation extinction risk and connectivity. We demonstrate the utility of the model using six years of data on the Chiricahua leopard frog Lithobates chiricahuensis , a threatened desert-breeding amphibian that was reintroduced to a network of sites in Arizona USA in 2003. Our results indicate that the model can generate precise predictions of extinction risk and produce connectivity maps that can guide conservation efforts following reintroduction. In the case of L. chiricahuensis , many sites were functionally isolated, and 82% of sites were characterized by intermittent water availability and high local extinction probabilities (0·84, 95% CI: 0·64–0·99). However, under the current hydrological conditions and spatial arrangement of sites, the risk of metapopulation extinction is estimated to be <3% over a 50-year time horizon. Low metapopulation extinction risk appears to result from the high dispersal capability of the species, the high density of sites in the region and the existence of predator-free permanent wetlands with low local extinction probabilities. Should management be required, extinction risk can be reduced by either increasing the hydroperiod of existing sites or by creating new sites to increase connectivity. Synthesis and applications . This work demonstrates how spatio-temporal statistical models based on ecological theory can be applied to forecast the outcomes of conservation actions such as reintroduction. Our spatial occupancy model should be particularly useful when management agencies lack the funds to collect intensive individual-level data.

Arizona, New Mexico↗

USGS2016

Habitat drives dispersal and survival of translocated juvenile desert tortoises

1.In spite of growing reliance on translocations in wildlife conservation, translocation efficacy remains inconsistent. One factor that can contribute to failed translocations is releasing animals into poor quality or otherwise inadequate habitat. 2.Here we used a targeted approach to test the relationship of habitat features to post-translocation dispersal and survival of juvenile Mojave desert tortoises Gopherus agassizii . 3.We selected three habitat characteristics—rodent burrows, substrate texture (prevalence and size of rocks), and washes (ephemeral river beds)–that are tied to desert tortoise ecology. At the point of release, we documented rodent burrow abundance, substrate texture, and wash presence and analysed their relationship to maximum dispersal. We also documented relative use by each individual for each habitat characteristic and analysed their relationships with survival and fatal encounters with a predator in the first year after release. 4.In general, the presence of refugia or other areas that enabled animals to avoid detection, such as burrows and substrate, decreased overall mortality as well as predator-mediated mortality. The presence of washes and substrate that enhanced the tortoises’ ability to avoid detection also associated with reduced dispersal away from the release site. These results indicate an important role for all three measured habitat characteristics in driving dispersal, survival, or fatal encounters with a predator in the first year after translocation. 5. Synthesis and applications . Resource managers using translocations as a conservation tool should prioritize acquiring data linking habitat to fitness. In particular, for species that depend on avoiding detection, refuges such as burrows and habitat that improved concealment had notable ability to improve survival and dispersal. Our study on juvenile Mojave desert tortoises showed that refuge availability or the distributions of habitat appropriate for concealment are important considerations for identifying translocation sites for species highly dependent on crypsis, camouflage, or other forms of habitat matching.

Journal of Applied Ecology↗

USGS2018

Decision making for mitigating wildlife diseases: From theory to practice for an emerging fungal pathogen of amphibians

Conservation science can be most effective in its decision‐support role when seeking answers to clearly formulated questions of direct management relevance. Emerging wildlife diseases, a driver of global biodiversity loss, illustrate the challenges of performing this role: in spite of considerable research, successful disease mitigation is uncommon. Decision analysis is increasingly advocated to guide mitigation planning, but its application remains rare. Using an integral projection model, we explored potential mitigation actions for avoiding population declines and the ongoing spatial spread of the fungus Batrachochytrium salamandrivorans ( Bsal ). This fungus has recently caused severe amphibian declines in north‐western Europe and currently threatens Palearctic salamander diversity. Available evidence suggests that a Bsal outbreak in a fire salamander ( Salamandra salamandra ) population will lead to its rapid extirpation. Treatments such as antifungals or probiotics would need to effectively interrupt transmission (reduce probability of infection by nearly 90%) in order to reduce the risk of host extirpation and successfully eradicate the pathogen. Improving the survival of infected hosts is most likely to be detrimental as it increases the potential for pathogen transmission and spread. Active removal of a large proportion of the host population has some potential to locally eradicate Bsal and interrupt its spread, depending on the presence of Bsal reservoirs and on the host's spatial dynamics, which should therefore represent research priorities. Synthesis and applications . Mitigation of Batrachochytrium salamandrivorans epidemics in susceptible host species is highly challenging, requiring effective interruption of transmission and radical removal of host individuals. More generally, our study illustrates the advantages of framing conservation science directly in the management decision context, rather than adapting to it a posteriori .

Journal of Applied Ecology↗

USGS2022

Primary production responses to extreme changes in North American Monsoon precipitation vary by elevation and plant functional composition through time

Primary production in dryland ecosystems is limited by water availability and projected to be strongly affected by future shifts in seasonal precipitation. Warm-season precipitation derived from the North American Monsoon contributes 40% of annual precipitation to dryland ecosystems in the southwestern U.S. and is projected to become more variable. However, there is large uncertainty on whether this variability will be expressed as either extreme wet or dry years and how primary production of different plant functional types will respond across widespread elevation gradients in this region. We experimentally imposed extreme drought and water addition treatments from 2016 – 2020, during which ambient warm-season precipitation declined to reach historic lows, to understand production sensitivity of dominant plant functional types along a 1,000 m elevation gradient. We found that the production responses of plant functional types to monsoon precipitation extremes were dependent on the number of treatment years that occurred across sites along the elevation gradient. C 4 perennial grasses were most responsive to precipitation manipulation treatments, followed by C 3 perennial grasses and annuals, while perennial forbs and shrubs had weak or no responses. C 4 perennial grass reductions due to extreme drought were generally stronger or occurred earlier at low elevation sites, while multi-year extreme drought extended negative effects to C 3 perennial grasses at high elevation, and all sites showed delayed responses to multi-year water addition. We found that the sensitivity of C 3 perennial grass production differed for extreme drought and water addition compared to ambient precipitation at one site, but other sites and plant functional types had similar sensitivities to the different treatment types. Synthesis . The upward advance of primary production responsiveness from single- to multi-year extreme changes in warm-season precipitation suggests more immediate shifts in functional composition and carbon cycling at low elevation, while high elevation ecosystems may become less resistant as the effects of extreme precipitation compound through time.

Arizona↗

USGS2017

Spatiotemporal variability of snow depletion curves derived from SNODAS for the conterminous United States, 2004-2013

Assessment of water resources at a national scale is critical for understanding their vulnerability to future change in policy and climate. Representation of the spatiotemporal variability in snowmelt processes in continental-scale hydrologic models is critical for assessment of water resource response to continued climate change. Continental-extent hydrologic models such as the U.S. Geological Survey National Hydrologic Model (NHM) represent snowmelt processes through the application of snow depletion curves (SDCs). SDCs relate normalized snow water equivalent (SWE) to normalized snow covered area (SCA) over a snowmelt season for a given modeling unit. SDCs were derived using output from the operational Snow Data Assimilation System (SNODAS) snow model as daily 1-km gridded SWE over the conterminous United States. Daily SNODAS output were aggregated to a predefined watershed-scale geospatial fabric and used to also calculate SCA from October 1, 2004 to September 30, 2013. The spatiotemporal variability in SNODAS output at the watershed scale was evaluated through the spatial distribution of the median and standard deviation for the time period. Representative SDCs for each watershed-scale modeling unit over the conterminous United States ( n = 54,104) were selected using a consistent methodology and used to create categories of snowmelt based on SDC shape. The relation of SDC categories to the topographic and climatic variables allow for national-scale categorization of snowmelt processes.

Journal of the American Water Resources Associatio↗

USGS2018

Floodplain trapping and cycling compared to streambank erosion of sediment and nutrients in an agricultural watershed

Floodplains and streambanks can positively and negatively influence downstream water quality through interacting geomorphic and biogeochemical processes. Few studies have measured those processes in agricultural watersheds. We measured inputs (floodplain sedimentation and dissolved inorganic loading), cycling (floodplain soil nitrogen [N] and phosphorus [P] mineralization), and losses (bank erosion) of sediment, N, and P longitudinally in stream reaches of Smith Creek, an agricultural watershed in the Valley and Ridge physiographic province. All study reaches were net depositional (floodplain deposition > bank erosion), had high N and P sedimentation and loading rates to the floodplain, high soil concentrations of N and P, and high rates of floodplain soil N and P mineralization. High sediment, N, and P inputs to floodplains are attributed to agricultural activity in the region. Rates of P mineralization were much greater than those measured in other studies of nontidal floodplains that used the same method. Floodplain connectivity and sediment deposition decreased longitudinally, contrary to patterns in most watersheds. The net trapping function of Smith Creek floodplains indicates a benefit to water quality. Further research is needed to determine if future decreases in floodplain deposition, continued bank erosion, and the potential for nitrate leaching from nutrient-enriched floodplain soils could pose a long-term source of sediment and nutrients to downstream rivers.

Virginia↗

USGS2019

Modeling connectivity of non‐floodplain wetlands: Insights, approaches, and recommendations

Representing hydrologic connectivity of non‐floodplain wetlands (NFWs) to downstream waters in process‐based models is an emerging challenge relevant to many research, regulatory, and management activities. We review four case studies that utilize process‐based models developed to simulate NFW hydrology. Models range from a simple, lumped parameter model to a highly complex, fully distributed model. Across case studies, we highlight appropriate application of each model, emphasizing spatial scale, computational demands, process representation, and model limitations. We end with a synthesis of recommended “best modeling practices” to guide model application. These recommendations include: (1) clearly articulate modeling objectives, and revisit and adjust those objectives regularly; (2) develop a conceptualization of NFW connectivity using qualitative observations, empirical data, and process‐based modeling; (3) select a model to represent NFW connectivity by balancing both modeling objectives and available resources; (4) use innovative techniques and data sources to validate and calibrate NFW connectivity simulations; and (5) clearly articulate the limits of the resulting NFW connectivity representation. Our review and synthesis of these case studies highlights modeling approaches that incorporate NFW connectivity, demonstrates tradeoffs in model selection, and ultimately provides actionable guidance for future model application and development.

Journal of the American Water Resources Associatio↗

USGS2020

elfgen: A new instream flow framework for rapid generation and optimization of flow-ecology relations

Effective water resource management requires practical, data‐driven determination of instream flow needs. Newly developed, high‐resolution flow models and aquatic species databases provide enormous opportunity, but the volume of data can prove challenging to manage without automated tools. The objective of this study was to develop a framework of analytical methods and best practices to reduce costs of entry into flow–ecology analysis by integrating widely available hydrologic and ecological datasets. Ecological limit functions (ELFs) describing the relation between maximum species richness and stream size characteristics (streamflow or drainage area) were developed. Species richness is expected to increase with streamflow through a watershed up to a point where it either plateaus or transitions to a decreasing trend in larger streams. Our results show that identifying the location of this "breakpoint" is critical for producing optimal ELF model fit. We found that richness breakpoints can be estimated using automated low‐supervision methods, with high‐supervision providing negligible improvement in detection accuracy. Model fit (and predictive capability) was found to be superior in smaller hydrologic units. The ELF model ("elfgen" R package available on GitHub: https://github.com/HARPgroup/elfgen ) can be used to generate ELFs using built‐in datasets for the conterminous United States, or applied anywhere else streamflow and biodiversity data inputs are available.

Virginia↗

USGS2023

Progradational-to-retrogradational styles of Palaeogene fluvial fan successions in the San Juan Basin, New Mexico

Basin-scale outcrop analyses of fluvial architecture in the Palaeogene San Juan Basin, New Mexico, document lateral and vertical trends in channel, floodplain and palaeosol characteristics. Herein, the uppermost part of the Palaeocene Nacimiento Formation and lower Eocene Cuba Mesa and Regina Members of the San Jose Formation are identified as deposits of large fluvial fans based on trends observed across the basin. Stratigraphic trends suggest two packages originated by fluvial fan progradation. Progradation of the lower fan system provides a new explanation for the transitional nature of a disconformity at the Nacimiento–San Jose Formation contact, previously thought to be a low-angle unconformity. The two fan systems are separated by a retrogradational interval that culminates in a depositional hiatus at the contact between the Cuba Mesa and Regina Members. This, combined with poor age constraints, indicates that the duration of the disconformity at the base of the Cuba Mesa Member may have been overestimated. Furthermore, the succession is interpreted as deposits of variable-discharge rivers, based on the combined abundance of upper flow regime and high deposition rate sedimentary structures indicative of intense flooding events, preservation of in-channel bioturbation and paedogenic modification indicating periods of prolonged dryness, lack of identifiable bar strata and alternations of poorly drained and well-drained floodplain deposits with pedofacies indicating alternating wet–dry cycles. This dataset adds to a growing body of evidence linking the formation of large fluvial fans to discharge variability and thus to hydroclimates with significant inter- and intra-annual precipitation variability and intense rainfall. A long-term stratigraphic shift from poorly drained to well-drained floodplain deposits across two progradational fan successions indicates that a predictive model suggesting downstream decreases in soil drainage conditions is not encompassing of all large fan systems, and instead suggests a transition to a more arid climate across the Palaeocene–Eocene boundary.

New Mexico↗

USGS2007

Deep-water chaunacid and lophiid anglerfishes (Pisces: Lophiiformes) off the Southeastern United States

Recent research cruises to deep (80–910 m) reef habitats off the south-eastern U.S. and in the northern Gulf of Mexico have provided new information on the diagnostic characteristics, behaviours, colour patterns in life, bottom associations, distributions and maximum sizes of species of the anglerfish genera Chaunax , Lophiodes and Sladenia . Chaunax stigmaeus occurred much further south than previously known (Blake Plateau off South Carolina), and all C. stigmaeus observed were found associated with dense beds of dead coral ( Lophelia pertusa ) rubble or on broken hard bottom. In contrast, Chaunax suttkusi was found on soft bottoms. Chaunax stigmaeus and C. suttkusi appear to be sympatric over a major portion of their ranges. Because knowledge of pigmentation in live or freshly caught Chaunax is critical to distinguish some members of the genus, changes in the colouration of C. suttkusi were noted and documented photographically immediately after death and after fixation. The yellow spots found on some, but not all specimens, temporarily disappeared completely after death, but they reappeared after fixation, slowly disappearing thereafter along with other carotenoid pigments. Lophiodes beroe and Lophiodes monodi were collected for the first time off the Atlantic coast of the U.S., being previously known only from the Gulf of Mexico, Caribbean Sea and the northern coast of South America. For both species ( L. beroe and L. monodi ), the collections included the two largest known representatives of the species (400 and 325 mm standard length, respectively). Lophiodes beroe commonly occurred on L. pertusa rubble, and seemed to prefer this habitat. Occupying such a habitat that is deep and difficult to sample probably explains how this common species escaped detection. Only a single L. monodi was collected or observed, so this species appears to be uncommon in this geographic area or at least so on coral rubble habitat. Detailed aspects of the colour patterns of both species were noted. In particular, L. beroe displayed a characteristic pattern of white patches in life that were not apparent after death. The first photographic documentation of the colour pattern in life and of the pharyngeal pigmentation of Lophiodes reticulatus is provided. The third known specimen of Sladenia shaefersi , and the first to be taken in U.S. waters was collected from coral rubble near the base of a steep 200 m scarp on the Blake Plateau.

Gulf of Mexico↗

USGS2008

A bioenergetic model for zebrafish Danio rerio (Hamilton)

A bioenergetics model was developed from observed consumption, respiration and growth rates for zebrafish Danio rerio across a range (18-32?? C) of water temperatures, and evaluated with a 50 day laboratory trial at 28?? C. No significant bias in variable estimates was found during the validation trial; namely, predicted zebrafish mass generally agreed with observed mass. ?? 2008 The Authors.

Journal of Fish Biology↗