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USGS2002

Riparian vegetation response to altered disturbance and stress regimes

Management of terrestrial carbon fluxes is being proposed as a means of increasing the amount of carbon sequestered in the terrestrial biosphere. This approach is generally viewed only as an interim strategy for the coming decades while other longer-term strategies are developed and implemented — the most important being the direct reduction of carbon emissions. We are concerned that the potential for rapid, disturbance-induced losses may be much greater than is currently appreciated, especially by the decision-making community. Here we wish to: (1) highlight the complex and threshold-like nature of disturbances — such as fire and drought, as well as the erosion associated with each — that could lead to carbon losses; (2) note the global extent of ecosystems that are at risk of such disturbance-induced carbon losses; and (3) call for increased consideration of and research on the mechanisms by which large, rapid disturbance-induced losses of terrestrial carbon could occur . Our lack of ability as a scientific community to predict such ecosystem dynamics is precluding the effective consideration of these processes into strategies and policies related to carbon management and sequestration. Consequently, scientists need to do more to improve quantification of these potential losses and to integrate them into sound, sustainable policy options.

Arizona↗
USGS2002

Transforming the Rockies: Human forces, settlement patterns, and ecosystem effects

The current ecological condition of the Rocky Mountains can be viewed from two somewhat opposing perspectives. The first is that human occupation has had relatively little effect on the Rockies: large natural, if not pristine, areas remain, and the region's open spaces provide wildlife habitat, majestic scenery, and a sense of wildness. Unlike the situation in, say, the Swiss Alps, where even high-elevation meadows have been mown and grazed intensively for as long as 500 years and many large mammals have been extirpated, most elements of Rocky Mountain landscapes and biota are reasonably unaltered. Even the presumption that Native Americans changed regional landscapes with deliberately set fires has been challenged by Baker and Ehle (2001) and others who think that most fires were lightning-caused or accidental ignitions. The second view is that humans have dramatically transformed the Rockies, at least since Euro-American settlement in the mid- to late 1800s. The slaughter of vast buffalo herds, the clearing of timber for railroad ties, and even the removal of whole hillsides in hydraulic placer mining represented substantial transformation. Ranch, resort, and residential development marks the latest incarnation of this transformation. Numerous, complex layers of land use have left landscape legacies, some of which may be unrecognized or underappreciated in modern assessments (Wohl 2001). Here we consider both perspectives because we are impressed with both the many effects of human use of the Rockies and the region's remaining wild landscapes. Ironically, much of the recent population growth and development in the Rockies is driven by the region's wild landscapes, which make the present widespread transformation seem all the more significant. It is, of course, the rapid clip of current human transformation—high population growth rates, pervasive rural residential development, and landscape fragmentation (Baron, Theobald, and Fagre 2000)—that worries ecologists and others concerned with Rocky Mountain ecosystems. So although we offer an overview of historical changes in the Rockies, especially since the 1800s, much of our attention here is on land uses, economies, and settlement patterns since the 1970s and on their future trends.

Book chapter↗
USGS2012

Spatial and temporal diet patterns of subadult and small adult striped bass in Massachusetts estuaries: Data, a synthesis, and trends across scales

Subadult and small adult (375–475 mm total length) striped bass Morone saxatilis are abundant and represent an important component of the recovered U.S. Atlantic coast stocks. However, little is known about these large aggregations of striped bass during their annual foraging migrations to New England. A quantitative understanding of trends in the diets of subadult and small adult migrants is critical to research and management. Because of the complexity of the Massachusetts coast, we were able to compare diets at multiple spatial, temporal, and taxonomic scales and evaluate which of these provided the greatest insights into the foraging patterns of this size of fish. Specifically, during spring through autumn, we quantified the diets of 797 migratory striped bass collected from 13 Massachusetts estuaries distributed among three geographic regions in two biogeographic provinces. Our data provided three useful results. First, subadult and young adult striped bass ate a season-specific mixture of fish and invertebrates. For example, more juvenile Atlantic herring Clupea harengus were eaten in spring than in summer or autumn, more juvenile Atlantic menhaden Brevoortia tyrannus were eaten in autumn than in spring or summer, amphipods were eaten primarily in the southern biogeographic province, and shrimp Crangon sp. were eaten in all locations and seasons. Second, examining diets by season was essential because of the temporal variability in striped bass prey. Grouping prey by fish and invertebrates revealed the potential for predictable differences in growth across geographic locations and seasons, based on the output from simple bioenergetics simulations. Third, of the three spatial scales examined, region provided the most quantitative and interpretable ecological trends. Our results demonstrate the utility of comparing multiple scales to evaluate the best way to depict diet trends in a migrating predator that seasonally uses different geographic locations.

Massachusetts↗
USGS2012

Effects of spatial subsidies and habitat structure on the foraging ecology and size of geckos

While it is well established that ecosystem subsidies—the addition of energy, nutrients, or materials across ecosystem boundaries—can affect consumer abundance, there is less information available on how subsidy levels may affect consumer diet, body condition, trophic position, and resource partitioning among consumer species. There is also little information on whether changes in vegetation structure commonly associated with spatial variation in subsidies may play an important role in driving consumer responses to subsidies. To address these knowledge gaps, we studied changes in abundance, diet, trophic position, size, and body condition of two congeneric gecko species ( Lepidodactylus spp.) that coexist in palm dominated and native (hereafter dicot dominated) forests across the Central Pacific. These forests differ trongly both in the amount of marine subsidies that they receive from seabird guano and carcasses, and in the physical structure of the habitat. Contrary to other studies, we found that subsidy level had no impact on the abundance of either gecko species; it also did not have any apparent effects on resource partitioning between species. However, it did affect body size, dietary composition, and trophic position of both species. Geckos in subsidized, dicot forests were larger, had higher body condition and more diverse diets, and occupied a much higher trophic position than geckos found in palm dominated, low subsidy level forests. Both direct variation in subsidy levels and associated changes in habitat structure appear to play a role in driving these responses. These results suggest that variation in subsidy levels may drive important behavioral responses in predators, even when their numerical response is limited. Strong changes in trophic position of consumers also suggest that subsidies may drive increasingly complex food webs, with longer overall food chain length.

Palmyra Atoll↗
USGS2015

Groundwater and surface-water interaction and effects of pumping in a complex glacial-sediment aquifer, phase 2, east-central Massachusetts

The U.S. Geological Survey, in cooperation with the Town of Framingham, Massachusetts, has investigated the potential of proposed groundwater withdrawals at the Birch Road well site to affect nearby surface water bodies and wetlands, including Lake Cochituate, the Sudbury River, and the Great Meadows National Wildlife Refuge in east-central Massachusetts. In 2012, the U.S. Geological Survey developed a Phase 1 numerical groundwater model of a complex glacial-sediment aquifer to synthesize hydrogeologic information and simulate potential future pumping scenarios. The model was developed with MODFLOW-NWT, an updated version of a standard USGS numerical groundwater flow modeling program that improves solution of unconfined groundwater flow problems. The groundwater model and investigations of the aquifer improved understanding of groundwater–surface-water interaction and the effects of groundwater withdrawals on surface-water bodies and wetlands in the study area. The initial work also revealed a need for additional information and model refinements to better understand this complex aquifer system. In this second phase of the study, the original groundwater flow model was revised to improve representation of groundwater and surface-water hydrology, stabilize the model, and reduce model error. The model was simplified by reducing the number of layers from 5 to 3 and adding the MODFLOW lake package (LAK) to simulate Lake Cochituate and Pod Meadow Pond and better represent interaction between the lakes and the aquifer. Model revisions improved stability and shortened run times, allowing use of automated parameter estimation software (PEST) to further refine the model hydraulic parameters and reduce simulation errors. Model simulations indicate that under average base-flow conditions, the Birch Road wells have a small effect on flow in the Sudbury River during most months, even at the maximum pumping rate of 4.9 ft 3 /s (3.17 Mgal/d). Maximum percent streamflow depletion in the Sudbury River caused by simulated pumping takes place during simulated drought conditions, when streamflow decreased by as much as 21 percent under maximum continuous pumping. Simulations also indicate that groundwater withdrawals at the Birch Road site could be managed so that adverse streamflow impacts are substantially ameliorated. Under the most ecologically conservative simulated drought conditions, simulated streamflow depletion was reduced from 21 percent to 3 percent by pumping at the maximum rate for 6 months rather than for 12 months. Simulations that return 10 percent of the Birch Road well withdrawals to Pod Meadow Pond indicate a modest reduction in the Sudbury River streamflow depletion and provide a larger percentage increase to streamflow just downstream of the pond. The groundwater model also indicates that well locations can have a large effect on the sustainable pumping rate and so should be chosen carefully. The model provides a tool for evaluating alternative pumping rates and schedules not included in this analysis.

Massachusetts↗
USGS2025

Demographic mechanisms of snowshoe hare population cycles in Yukon, Canada

One hundred years have elapsed since Charles Elton (1924) described the periodic fluctuations in North American snowshoe hare abundance, yet mechanisms underlying 9–11-year population cycles in snowshoe hares continue to be debated. We applied multistate capture–mark–recapture models to long-term field data (1977–2020) based on >20,000 captures of >7000 unique snowshoe hares ( Lepus americanus ) from Kluane Lake, Yukon, Canada, to estimate and model state-specific demographic parameters. Juveniles had the lowest and reproductive adult females the highest apparent survival. Apparent survival of all sex-age classes was highest during the mid- and late-breeding seasons and was generally better during the increase phase. Conditional probability of females transitioning from non-reproductive to reproductive state, and reproductive females remaining in the reproductive state, increased substantially as the population transitioned from low to increase phase throughout the breeding season. Analysis of stage-structured matrix population models revealed that population-dynamic characteristics were strongly phase-specific, and also varied across seasons, with the increase phases being characterized by high monthly asymptotic population growth rate. Snowshoe hares experienced short stage-specific generation time during the early breeding season across all phases; they experienced relatively long generation time during the increase and low phase of the mid-breeding season, and the increase and peak phase of the late breeding season. Elasticity analyses showed that asymptotic population growth rate was proportionately most sensitive to changes in survival of adult females across all phases and seasons. However, retrospective life table response experiment analysis showed that rapid growth of the snowshoe hare populations during the increase phase was due to improvements in reproductive transitions and pre-weaning survival, whereas population declines are caused primarily by reduced survival (primarily, pre-weaning survival), with reduced reproductive transitions and smaller litter sizes playing a secondary role. Our results suggest that cyclic populations of snowshoe hares are characterized by complex demographic and population-dynamic patterns, depending on phase of the cycle and reproductive season, and that different demographic mechanisms underlie rapid population growth during the increase phase, and swift population declines as the population transitions from the peak to the decline phase. Because our study represents the first comprehensive demographic and population-dynamic study of a cyclic population, similar studies would be needed to test the generalities of our conclusions. Whereas density-dependent predation has been shown to be the primary cause of phase-related changes in survival, future research should focus on identifying mechanisms underlying phase-related changes in reproductive parameters.

Yukon↗
USGS2026

Small creatures, big challenge: A review of current knowledge and assessment of research needs to inform water withdrawal management for the Duck River's freshwater mussel fauna

The Duck River is a remarkable national resource, boasting outstanding biodiversity (Ahlstedt et al. 2017). It contains 151 fish species, over 60 mussel species, and 22 snail species, many of which are federally listed (Etnier and Starnes 1993; Johnson et al. 2013; Ahlstedt et al. 2017; Womble and Rosenberger 2025a). The Duck River watershed is at a pivotal time in its management and ecological history due to significant growth in human population and economic activity. The consequent increase in surface water demand presents challenges for sustainable water resource management. The Tennessee Department of Environment and Conservation (TDEC) has permitted or proposed to permit eight water utilities to withdraw over 77 million gallons per day (mgd) from the Duck River, representing > 40% increase from previously permitted amounts (USFWS 2025). On November 20, 2024, Tennessee Governor Bill Lee signed Executive Order No 108 to ensure long-term stability of the Duck River watershed through balancing economic growth, water resource management, and environmental conservation. Some primary components of this plan are the creation of a Comprehensive Regional Drought Management Plan, the development of a Habitat Conservation Plan, and the establishment of the Duck River Watershed Planning Partnership (DRWPP). Although the planning partnership is not focused on a sole aspect of the Duck River, but the watershed as a whole, the mussel assemblages of the Duck River have been a particular focus due to their importance in providing ecosystem services, sensitivity to water quality, conservation status, and sensitivity to periodic drought conditions in this system. With multiple state and federal agencies involved in managing the Duck River’s unique water resources, a focused review on how future water management could affect the freshwater mussel communities in the Duck River will contribute to this process. Our objectives of this review are to: 1. Review the effects of changing flow regimes on mussels, with emphasis on the effect of droughts/low flows, highlighting key processes/factors affecting mussels. 2. Highlight critical data gaps that could allow future, evidence-based water management decisions in this system. 3. Propose research topics to address critical data gaps and enable evidence-based water management decisions that consider the needs of freshwater mussels. Freshwater mussels are a critical component of riverine ecosystems, providing ecosystem services including water filtration, nutrient cycling, and habitat provision (Vaughn et al. 2004; Haag 2012) that benefit human communities. Environmental flows, also referred to as ecological or e-flows, refer to the quantity, timing, and quality of water flows necessary to maintain the ecological health of rivers, wetlands, and other aquatic ecosystems (Acreman and Dunbar 2004; Acreman 2016). For freshwater mussels, environmental flows include maintaining a flow regime and associated water quality regimes that are favorable for both juveniles and adults while also seasonally supporting host fish and the survival of settling glochidia (i.e., larval mussels) in suitable environments (Gates et al. 2015). Freshwater mussels are adapted to the natural flow regime of their native streams, including seasonal variability in flows. As sedentary filter feeders, mussels require adequate water flow to provide oxygen and food (Allen and Vaughn 2009); however, they also require periods of low flow to increase access to fish hosts and to ensure juveniles are not displaced (Gates et al 2015). Mussels are sensitive to water quality conditions, including pollutants, sedimentation, and artificial alterations of temperature and pH (Strayer and Malcom 2012). Mussel community characteristics, including presence, abundance, and species richness, generally increase with stream size (e.g., stream order); however, responses to changes in flow conditions are often species-specific, and the magnitude and timing of extreme flow conditions have more predictive power for mussel community response than general changes in flow (Lopez and Vaughn 2021). Complex hydraulic variables, such as relative shear stress and Reynolds number, can be strong predictors of mussel community responses because they combine simple hydraulic variables (e.g., velocity, depth) with stream channel characteristics, such as substrate composition and dynamics. Droughts directly and indirectly affect mussels by influencing their physiology, behavior, reproduction, and ecosystem roles. Mass mussel die-offs during droughts and low water conditions are widely documented (Vaughn et al. 2015; Sousa et al. 2018; Dubose et al. 2019). Droughts can also lead to a shift in mussel community composition, with drought-tolerant species becoming more dominant while more sensitive species experience declines (Galbraith et al, 2010; Lopez et al. 2022; Vaughn and Atkinson 2025). Droughts affect mussels through direct mortality from stranding as well as physiological stress from altered water temperature and quality, reduced habitat and food availability and quality, increased predation and competition, disruption of reproductive cycles, and increased susceptibility to disease and pathogens. Although the effects of droughts, water withdrawals, and low flow conditions on mussels are an increasing area of study, there is a general paucity of data-driven consensus regarding optimal mitigation approaches and strategies (Cushway et al. 2024). Long-term management decisions regarding water withdrawals, particularly during extended or multi-year drought conditions, may consider factors beyond direct mortality such as the sublethal effects of drought and low flow conditions on freshwater mussels for a comprehensive understanding of the effects of prolonged low flows on freshwater mussels and aquatic communities.

Tennessee↗
USGS2019

Review of Sky dance of the woodcock: The habits and habitats of a strange little bird by Greg Hoch

American Woodcock ( Scolopax minor ) have enthralled conservationists (including Aldo Leopold), bird watchers, wildlife enthusiasts, hunters, and others interested in the natural world for centuries. No doubt, woodcock also have enthralled humans in North America for millennia prior to written descriptions of the woodcock’s courtship displays, habitat preferences, and curious behavior and anatomy. As perhaps the most extensively studied species of shorebird in the world, there is a rich and extensive literature, both scientific and popular, focused on woodcock ecology, behavior, and hunting. To that extensive body of literature, Sky Dance of the Woodcock provides an updated summary of their natural history, habitat relations, and conservation. Sky Dance of the Woodcock takes its title from the courtship display of male woodcock, which consists of an elaborate aerial flight incorporating sound produced both vocally and mechanically via highly modified flight feathers. The aerial displays are accompanied by similarly unusual behavior on the ground, including a distinctive ‘peent’ call. This courtship display happens across much of eastern North America each spring, and Hoch uses this wonder to capture the imagination of the readers of his text. Hoch begins the book with an overview of some of the mystery and fascination surrounding woodcock and builds from that opening to describe woodcock anatomy, natural history, and behavior, before describing their courtship display in greater detail. From there, Hoch describes woodcock-habitat relations, provides a historical overview of woodcock hunting, identifies current threats to woodcock populations, summarizes past and recent woodcock research, and finally, presents an updated overview of woodcock conservation and habitat management. Throughout, there is sometimes surprising information about things as simple as what woodcock eat, to more complex assessment of how woodcock use landscapes and migrate to and from spring and summer breeding areas. This book will undoubtedly appeal to woodcock enthusiasts of a variety to stripes. Woodcock hunters and bird watchers alike will learn something about woodcock-habitat relations, behavior, and conservation. Professional biologists and researchers will benefit from Hoch’s synthesis of a wide range of information about woodcock, and landowners and managers can use some of the concepts in this book to inform their decisions about how to manage lands under their control. Along the way, everyone who reads Sky Dance of the Woodcock is likely to come away with an enhanced appreciation of this captivating bird.

Prairie Naturalist↗
USGS2025

UAS-based geomorphic change detection of incised montane meadow stream channels with low-tech process-based restoration treatments

Context Montane meadows play an important hydrologic role in headwater catchments, but past land use has largely degraded their condition. Low-tech restoration methods, such as beaver dam analogs (BDAs), are increasingly used to support recovery of incised streams by promoting key geomorphic processes. However, there remains a need for studies that leverage UAS for monitoring low-tech restoration treatments in incised meadow systems. Objectives This study maps and characterizes geomorphic changes in two incised meadow stream channels in Red Clover Valley, CA with installed beaver dam analog structures. We used UAS-based photogrammetric surveys to track changes over a three-year period (2021–2023). Methods Geomorphic change was assessed using DEM differencing with error thresholding, repeat geomorphic unit (GU) classification, and Shannon Diversity Index (SHDI) to measure spatial shifts in geomorphic complexity. Results Geomorphic responses varied by site and survey period. The subchannel B (SCB) site exhibited net deposition, while the lower Dixie Creek (LDC) site showed net erosion. BDAs appeared to enhance geomorphic activity, particularly in LDC, where near BDA areas showed greater sediment deposition and localized erosion compared to reference sites. SHDI values were positively correlated with erosion at both sites, suggesting that erosional processes may have promoted geomorphic diversity by creating or reorganizing GU in the incised channels. Conclusions UAS-SfM surveys captured erosion and deposition patterns and revealed the influence of BDAs and local channel characteristics on geomorphic change and unit diversity. These findings highlight the utility of UAS methods for monitoring restoration impacts in incised montane meadow streams.

California↗
USGS2019

Integrated modeling reveals shifts in waterfowl population dynamics under climate change

1. Climate change has been identified as one of the most important drivers of wildlife populations. The development of appropriate conservation strategies relies on reliable predictions of population responses to climate change, which require in-depth understanding of the complex relationships between climate and population dynamics through density dependent demographic processes. Integrated population models (IPMs) are a type of modeling approach that unify the analyses of demography and abundance data, providing opportunities to understand and predict population demography and dynamics under climate change. 2. In this study we developed dynamic N-mixture models for large scale population estimates, which became an important component of the IPM we used in data analysis. We then analyzed four decades (1974-2014) of Mallard ( Anas platyrhynchos ) breeding population survey, band-recovery, and climate data covering a large spatial extent from North American prairies through boreal habitat to Alaska. Our goals were to examine the complex relationships among climate, density dependent processes, waterfowl population demography and dynamics, identify the key demographic parameters that are sensitive to climate change and are influential to population growth, and forecast population responses to climate change. 3. Our results revealed the interactive effects of temperature and density dependent processes on Mallard recruitment and to a less extent apparent survival. We also found that recruitment explained more variance of population growth than apparent survival. We then forecasted a decrease in Mallard breeding population density in the Northern Prairie Potholes and an increase in Mallard breeding population density in the northern part of our study area, indicating potential shifts in Mallard population dynamics under future climate change. 4. Synthesis and applications Different strategies need to be considered across regions to conserve waterfowl populations under climate change. Strategies that facilitate recruitment are essential for high-density populations that are relatively vulnerable to climate change. By contrast, low-density populations are relatively resilient to climate change and their habitats may serve as future climate refugia. Adaptive management is essential for evaluating management consequences. Our modelling framework approach can be easily adapted for other species and thus has wide applications in ecology and conservation.

Ecography↗
USGS2024

Physics to fish—Understanding the factors that create and sustain native fish habitat in the San Francisco Estuary

Executive Summary The Bureau of Reclamation (Reclamation) operates the Central Valley Project (CVP), one of the nation’s largest water projects. Reclamation has an ongoing need to improve the scientific basis for adaptive management of the CVP and, by extension, joint operations with California’s State Water Project. The U.S. Geological Survey (USGS) works cooperatively with the Bureau of Reclamation to provide scientific support for the management of Reclamation’s CVP project. Major habitat restoration efforts and a new water-diversion point are planned to benefit delta smelt ( Hypomesus transpacificus ) and other species of concern while ensuring the reliability of water supply. In addition, various flow actions and management activities have been identified as possible methods to increase populations of delta smelt and salmonid ( Oncorhynchus spp.) runs of concern. The overarching goal of this cooperative project was to provide Reclamation with the scientific information needed to evaluate the efficacy of ongoing and future adaptive management actions and to improve the scientific basis for more flexible CVP operations that would achieve water-supply reliability and fish protection. The research and monitoring described in this report comprises the period 2015–19 and focuses on management issues related to native fish species of concern, especially delta smelt. Conserving the delta smelt population while providing a reliable water supply is a primary management and policy issue in California. Our approach for this cooperative project is based on the “physics to fish” concept, the idea that high-quality habitat is generated and sustained by the interaction between physical processes and the landscape. These interactions create a template for chemical and biological processes that can change across a variety of spatial and temporal scales. Following this concept, this project (hereafter referred to as “the physics to fish project”) included monitoring and studies of water flows, sediments, water quality, and invertebrate and fish dynamics across a range of spatial and temporal scales and in regions relevant to resource managers tasked with managing water supplies and ecosystem health in the San Francisco Estuary. The intent of this approach was to document the habitat conditions, important processes, and interactions among them that create high-quality habitat for native fishes so that the likely effects of future management actions (for example, habitat restoration) can be objectively assessed at the local (site-specific), regional (within subregions of the estuary), and landscape (across the entire estuary and beyond) scales. Hydrodynamically, the upper estuary (landward of Carquinez Strait) is characterized by a fixed volume of tidally exchanged water (for example, tidal prism) that interacts with the existing channel network and bathymetry to create regions with differing hydrodynamics. Our results indicate that careful study of construction or reoperation of existing infrastructure to perform management actions can help (1) improve the accuracy of hydrodynamic models; (2) further understanding of ecological effects; and (3) enhance abilities to predict ecological outcomes. At the local scale, we developed a new concept called the Lagrangian to Eulerian (LE) ratio that can be used as a tool for understanding the importance of various hydrodynamic processes in specific channels or channel networks and for forecasting transport dynamics. Channels with LE ratios<1 in a channel network or in a dead-end slough are hydrodynamically able to develop an exchange zone between two parcels of water that may have different chemical and physical properties. In a dead-end channel, there is a landward region with long residence time (no-exchange zone) and a seaward region with short residence time (high-exchange zone) that are well mixed with seaward waters. At the transition (exchange zone) between the high and no-exchange regions, a gradient will form in water-quality constituents that differ in concentration between the landward and seaward waters. Turbidity affects fish habitat and has declined through time in the San Francisco Estuary. Average turbidity across the Sacramento–San Joaquin Delta (hereafter referred to as “the Delta”) is dependent on annual hydrology. In dry years, the region around Cache Slough (known regionally as the “Cache Slough Complex”) in the northern Delta is generally more turbid than Suisun Bay and the lower Sacramento River. When the Yolo By-Pass (known regionally as “Yolo Bypass”), a large flood bypass that runs parallel to the Sacramento River in the northern Delta, is not flooding and river flows are lower, sediment is usually transported into the Cache Slough Complex because flood tides dominate ebb tides, resulting in transport of suspended sediment from seaward areas of the upper estuary into the Cache Slough Complex. These hydrodynamic conditions also favor the formation of turbidity maximums (TMs) in the Cache Slough Complex. The TMs are areas of higher suspended-sediment concentration, providing higher-turbidity habitat favored by some fishes, including delta smelt, and they can also concentrate other constituents, including phytoplankton and organic carbon that can be important in food webs. Pelagic primary production by phytoplankton is the basis for Delta food webs supporting pelagic fishes such as delta smelt; however, phytoplankton abundance in the Delta has declined during recent decades. We examined how nutrients, hydrodynamics, and other factors affect phytoplankton blooms. Based on our results, we developed three new concepts of phytoplankton bloom formation in the Delta, each associated with a distinct set of hydrologic conditions. First, productivity cascades highlighted how local processes can contribute to phytoplankton blooms observed at the regional scale. Second, we observed phytoplankton blooms in the upper San Francisco Estuary that were associated with transport out of Yolo By-Pass (transport blooms). Third, we also documented a series of phytoplankton blooms that were in the confluence area at the landward edge of Suisun Bay. The conditions leading to creation of confluence phytoplankton blooms are not yet understood, but the confluence region connects the Cache Slough Complex with Suisun Marsh. Therefore, blooms in this area have the potential to spread to large areas of the Delta. At the landscape scale, the distribution of the invasive clams ( Potamocorbula amurensis and Corbicula fluminea , hereafter referred to as “ Corbicula ”) is driven by salinity. At smaller spatial scales, the distribution of either species is sensitive to multiple factors affecting survival and reproduction, complicating efforts to predict distribution and abundance without considering local-scale conditions across the area of interest. In the Cache Slough Complex, the area landward of the exchange zone in regions with LE ratio<1 were characterized by low abundances of Corbicula probably because recruits from seaward areas are not transported past the exchange zone and because there are no landward tributaries with adult Corbicula to provide an upstream source of recruits. Corbicula biomass was highest near or downstream from the exchange zone consistent with Corbicula grazing on phytoplankton produced in the exchange zone or transported from the no-exchange zone. The severity of Corbicula grazing could be reduced by manipulating the hydrodynamic characteristics of waterways; however, the beneficial and harmful effects on the organisms meant to benefit from increased phytoplankton production, including zooplankton and fish species of concern, should be thoroughly examined before manipulating hydrodynamic characteristics. The distribution of fishes at the landscape scale is generally driven by the position of the salinity field in the estuary. The physics to fish project compared distributions of fishes at Ryer Island, a tidal wetland in Suisun Bay and a region of variable salinity, with fish distributions at the Cache Slough Complex, a freshwater region. At Ryer Island, there was an absence of freshwater invasive species and an abundance of native species, such as Sacramento splittail ( Pogonichthys macrolepidotus ), tule perch ( Hysterocarpus traskii ), and Sacramento pikeminnow ( Ptychocheilus grandis ). The native species were almost exclusively captured in wetland and nearshore shallow-water habitat regardless of water-quality conditions. In the Cache Slough Complex, our regional scale objective was to elucidate how hydrodynamic-physical habitat interactions drive fish-community structure. Our studies showed that dendritic channel systems were better able to support native species, while intertidal habitats supported those species best able to exploit the transient character of the habitat. Habitats upstream from the exchange zone were especially important in supporting high numbers of native fishes relative to within or downstream from the exchange zone. Many of the native species were associated with tidal marsh in the no-exchange zone. More pelagic-oriented, mobile species, such as Striped Bass ( Morone saxatilis ), threadfin shad ( Dorosoma petenense ), and Sacramento pikeminnow, were more affected by water-quality conditions, such as turbidity. The physics to fish concept developed in this project provides a framework for designing individual projects and for considering the cumulative effects of multiple projects in a region, using the LE ratio as a guiding metric. The physics to fish concept may also provide a suitable framework for coordinating management actions. Tidal wetlands can function in several ways in the hydrodynamic framework. Relatively small tidal wetlands with short channel networks and with LE ratios>1 are not able to maintain a landward no-exchange zone or an exchange zone. This likely means that any contributions to pelagic food webs would be limited to resources derived from wetland vegetation, which can include dissolved and particulate organic matter (detritus) and populations of consumers that can increase in abundance based on those resources. The fate of the contributed production from these channels depends on the characteristics of the receiving waters seaward of the tidal wetland. If these channels join a large system such as Suisun Bay, then any contribution is likely to be rapidly dispersed in the larger volume; however, the channel junction might provide a focal point for consumers, such as fishes, to congregate and feed on material leaving the wetland on ebb tides before it is dispersed in the larger volume. Fishes might also access these resources by entering the wetland. The physics to fish project has established a foundation and several new concepts for understanding how habitat restoration can benefit native fish populations at the local and regional levels. Many of the ideas regarding habitat restoration and channel modifications outlined in this report could help guide management actions that could improve conditions for native fishes at little or no water cost beyond water already dedicated to other management actions. A complete list of products originating from this work is provided in appendix 1.

California↗
USGS2003

Composition, complexity, and tree mortality in riparian forests in the central Western Cascades of Oregon

Riparian forests contribute to the diversity and function of both terrestrial and aquatic ecosystems. To assess some of these contributions, we compared tree composition, stand complexity, and temporal patterns of tree mortality on permanent plots in seven mature and old-growth stands representing upland forests and forests along low- and mid-order streams in the Western Cascade Range of Oregon. We also assessed recruitment of large wood into stream channels due to tree mortality, both by direct measurement and by estimation from tree mortality and location data. Stands differed in composition due to both stream order and successional stage. Stands on mid-order streams had high abundance of hardwood trees and/or Thuja plicata . Stand complexity (variability in tree diameters, tree life-form diversity, and tree species diversity), was high in stands on mid-order streams and in the upland, old-growth stand. Tree mortality was exceptionally high in six of the seven stands in 1996, the year in which the largest flood during the study occurred. However, only in the one stand on an unconstrained reach of a mid-order stream was mortality primarily due to flooding. Estimated recruitment of wood was much higher from the stand on the unconstrained reach than from the other stands on mid-order streams, suggesting that unconstrained reaches may be important for efforts to maintain or restore large wood in streams.

Oregon↗
USGS2019

Trade-offs relating to grassland and forest mine reclamation approaches in the central Appalachian region and its implications for the songbird community

Surface mining in the Appalachian region, USA, converts large areas of mature forest to early-successional habitat. This shift in landscape structure has the potential to reduce habitat availability and suitability for forest-dwelling songbirds by reducing and fragmenting mature forest, but also to increase habitat availability for grassland and shrubland-associated songbirds. We examined the influence of mountaintop mining/valley fill (MTMVF) reclamation habitats (grassland, shrubland, and remnant forest) on songbird community composition and abundance at three former MTMVF mines in southwestern West Virginia, relative to intact forest. We quantified the songbird community in 1999 and 2000 using point counts arranged throughout the mine complexes to assess landscape composition of the songbird community. Community analysis showed songbirds had strong associations with their respective guild based on species’ habitat preferences. Although remnant and intact forest treatments had similar species compositions, the forest interior guild had greater richness in intact than remnant forest. Total species richness was greatest in the reclaimed shrubland treatment. Focal species analysis followed similar trends as community assessments, as species’ abundances within treatment types were strongly associated with species’ habitat preferences. Our study indicates reclamation habitat decisions (i.e. grasslands versus forests) can have large effects on avian community composition. Determining appropriate mine restoration actions depends on the suite of species desired for long-term occupancy and their conservation priority.

Appalachian Basin↗
USGS2014

Character, distribution, and ecological significance of storm wave-induced scour in Rhode Island Sound, USA

Multibeam bathymetry, collected during NOAA hydrographic surveys in 2008 and 2009, is coupled with USGS data from sampling and photographic stations to map the seabed morphology and composition of Rhode Island Sound along the US Atlantic coast, and to provide information on sediment transport and benthic habitats. Patchworks of scour depressions cover large areas on seaward-facing slopes and bathymetric highs in the sound. These depressions average 0.5-0.8 m deep and occur in water depths reaching as much as 42 m. They have relatively steep well-defined sides and coarser-grained floors, and vary strongly in shape, size, and configuration. Some individual scour depressions have apparently expanded to combine with adjacent depressions, forming larger eroded areas that commonly contain outliers of the original seafloor sediments. Where cobbles and scattered boulders are present on the depression floors, the muddy Holocene sands have been completely removed and the winnowed relict Pleistocene deposits exposed. Low tidal-current velocities and the lack of obstacle marks suggest that bidirectional tidal currents alone are not capable of forming these features. These depressions are formed and maintained under high-energy shelf conditions owing to repetitive cyclic loading imposed by high-amplitude, long-period, storm-driven waves that reduce the effective shear strength of the sediment, cause resuspension, and expose the suspended sediments to erosion by wind-driven and tidal currents. Because epifauna dominate on gravel floors of the depressions and infauna are prevalent in the finer-grained Holocene deposits, it is concluded that the resultant close juxtaposition of silty sand-, sand-, and gravel-dependent communities promotes regional faunal complexity. These findings expand on earlier interpretations, documenting how storm wave-induced scour produces sorted bedforms that control much of the benthic geologic and biologic diversity in Rhode Island Sound.

Rhode Island↗
USGS1995

Vine maple clone growth and reproduction in managed and unmanaged coastal Oregon Douglas-fir forests

Vine maple (Acer circinatum Pursh.) clone development, expansion, and regeneration by seedling establishment were studied in 5-240 yr old managed and unmanaged Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in coastal Oregon. Stem length, number of stems, and crown area were all significantly (P ≤ 0.01) related to stand age, and clone development was most rapid during the first 50 yr of stand development. Following clear-cutting, clones were clumps of 1-3 m long upright stems. Fifty years after disturbance, clones consisted of 5-15 drooping aerial stems >10 m long and basal sprouts 1-2 m long; some stems had been pinned to the forest floor by fallen trees or branches and had layered. In stands >120 yr in age, clones were often quite complex, composed of several decumbent stems each of which connected the ramets of 1-10 new aerial stems. Vine maple clone expansion occurs by the layering of long aerial stems. Over 95% of the layered stems we observed had been pinned to the forest floor by fallen debris. Unsevered stems that we artificially pinned to the forest floor initiated roots within 1 yr. Thinning may favor clonal expansion because fallen slash from thinning often causes entire clones to layer, not just individual stems. Clonal vine maple seed production and seedling establishment occurred in all stages of stand development except dense, young stands following crown closure. There were more seedlings in thinned stands than in unthinned stands and in unburned clearcuts than in burned clearcuts.

Ecological Applications↗
USGS2012

Science to support the understanding of Ohio's water resources

Ohio’s water resources support a complex web of human activities and nature—clean and abundant water is needed for drinking, recreation, farming, and industry, as well as for fish and wildlife needs. The distribution of rainfall can cause floods and droughts, which affects streamflow, groundwater, water availability, water quality, recreation, and aquatic habitats. Ohio is bordered by the Ohio River and Lake Erie and has over 44,000 miles of streams and more than 60,000 lakes and ponds (State of Ohio, 1994). Nearly all the rural population obtain drinking water from groundwater sources. The U.S. Geological Survey (USGS) works in cooperation with local, State, and other Federal agencies, as well as universities, to furnish decisionmakers, policymakers, USGS scientists, and the general public with reliable scientific information and tools to assist them in management, stewardship, and use of Ohio’s natural resources. The diversity of scientific expertise among USGS personnel enables them to carry out large- and small-scale multidisciplinary studies. The USGS is unique among government organizations because it has neither regulatory nor developmental authority—its sole product is reliable, impartial, credible, relevant, and timely scientific information, equally accessible and available to everyone. The USGS Ohio Water Science Center provides reliable hydrologic and water-related ecological information to aid in the understanding of use and management of the Nation’s water resources, in general, and Ohio’s water resources, in particular. This fact sheet provides an overview of current (2012) or recently completed USGS studies and data activities pertaining to water resources in Ohio. More information regarding projects of the USGS Ohio Water Science Center is available at http://oh.water.usgs.gov/.

Ohio↗
USGS2001

Spatial paradigms of lotic diatom distribution: A landscape ecology perspective

Spatial distributional patterns of benthic diatoms and their relation to current velocity were investigated in an unshaded cobble-bottom reach of White Creek (Washington County, NY). On 27 August 1999, diatoms were sampled and current velocity and depth were measured on a regular square sampling grid with a grain size of 0.01 m2, interval of 0.5 m, and extent of 16 m2. The relative abundance of the 18 common diatom species enumerated in the 81 samples was subjected to detrended correspondence analysis (DCA). The first axis (DCA1) explained 51% of the variance in diatom data and separated the samples according to current regimes. The spatial autocorrelation of DCA1 sample scores in deposition and erosion regions of White Creek was determined by Moran's I statistic to indicate patch size. In White Creek the patch length of all diatom communities was more than 3.1 m, whereas the patch width was 1 m in the deposition region and 0.5 m in the erosion region. There were 5 dominant diatom taxa, Achnanthes minutissima Ku??tz. et vars, Fragilaria capucina Dezmazie??res et vars, F. crotonensis Kitt., Diatoma vulgaris Bory, and Synedra ulna (Nitz.) Ehr. et vars. The patch length of the dominant species varied from 1 to more than 4.1 m, whereas the patch width, if defined, was 0.5 m. Achnanthes minutissima and F. capucina, the two diatom species with the highest relative abundance, displayed spatially structured patches of low abundance and comparatively random patches of high abundance, suggesting broad scale abiotic control of species performance in low abundance regions and finer scale biotic control of high abundance areas. Another objective of this study was to test the hypothesis that higher current velocities, which generally impede immigration, would increase randomness and complexity (i.e. homogeneity of diatom distributional patterns). The spatial complexity in low versus high velocity transects was determined by calculating the respective fractal dimension (D) of DCA1 scores. D of DCA1 was higher in the higher current velocity transects, suggesting that spatial complexity and homogeneity of diatom communities increased in faster currents. Partial canonical correspondence analysis was conducted on diatom, environmental, and spatial data to assess how much of the variance in species distribution could be attributed to environmental (current velocity and depth) versus spatial factors. The variance of species data, explained by the environment (exclusively current velocity), was 38%; whereas space alone contributed only 10%, indicating that 1) current velocity was the major factor that controlled diatom distribution in streams and 2) there were other spatially dependent variables, most likely biotic, but their role in shaping diatom communities was minor.

Journal of Phycology↗
USGS2014

Self-recognition in corals facilitates deep-sea habitat engineering

The ability of coral reefs to engineer complex three-dimensional habitats is central to their success and the rich biodiversity they support. In tropical reefs, encrusting coralline algae bind together substrates and dead coral framework to make continuous reef structures, but beyond the photic zone, the cold-water coral Lophelia pertusa also forms large biogenic reefs, facilitated by skeletal fusion. Skeletal fusion in tropical corals can occur in closely related or juvenile individuals as a result of non-aggressive skeletal overgrowth or allogeneic tissue fusion, but contact reactions in many species result in mortality if there is no ‘self-recognition’ on a broad species level. This study reveals areas of ‘flawless’ skeletal fusion in Lophelia pertusa , potentially facilitated by allogeneic tissue fusion, are identified as having small aragonitic crystals or low levels of crystal organisation, and strong molecular bonding. Regardless of the mechanism, the recognition of ‘self’ between adjacent L. pertusa colonies leads to no observable mortality, facilitates ecosystem engineering and reduces aggression-related energetic expenditure in an environment where energy conservation is crucial. The potential for self-recognition at a species level, and subsequent skeletal fusion in framework-forming cold-water corals is an important first step in understanding their significance as ecological engineers in deep-seas worldwide.

Scientific Reports↗