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At least 1,153 records · Page 64Linked to original sources
USGS2016

Relationships of three species of bats impacted by white-nose syndrome to forest condition and management

Forest management activities can have substantial effects on forest structure and community composition and response of wildlife therein. Bats can be highly influenced by these structural changes, and understanding how forest management affects day-roost and foraging ecology of bats is currently a paramount conservation issue. With populations of many cave-hibernating bat species in eastern North America declining as a result of white-nose syndrome (WNS), it is increasingly critical to understand relationships among bats and forest-management activities. Herein, we provide a comprehensive literature review and synthesis of: (1) responses of northern long-eared ( Myotis septentrionalis ) and tri-colored ( Perimyotis subflavus ) bats—two species affected by WNS that use forests during summer—to forest management, and (2) an update to a previous review on the ecology of the endangered Indiana bat ( Myotis sodalis ).

General Technical Report↗
USGS2013

California State Waters Map Series: Offshore of Carpinteria, California

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Offshore of Carpinteria map area lies within the central Santa Barbara Channel region of the Southern California Bight. This geologically complex region forms a major biogeographic transition zone, separating the cold-temperate Oregonian province north of Point Conception from the warm-temperate California province to the south. The map area is in the southern part of the Western Transverse Ranges geologic province, which is north of the California Continental Borderland. Significant clockwise rotation—at least 90°—since the early Miocene has been proposed for the Western Transverse Ranges province, and the region is presently undergoing north-south shortening. The small city of Carpinteria is the most significant onshore cultural center in the map area; the smaller town of Summerland lies west of Carpinteria. These communities rest on a relatively flat coastal piedmont that is surrounded on the north, east, and west by hilly relief on the flanks of the Santa Ynez Mountains. El Estero, a salt marsh on the coast west of Carpinteria, is an ecologically important coastal estuary. Southeast of Carpinteria, the coastal zone is narrow strip containing highway and railway transportation corridors and a few small residential clusters. Rincon Point is a well-known world-class surf break, and Rincon Island, constructed for oil and gas production, lies offshore of Punta Gorda. The steep bluffs backing the coastal strip are geologically unstable, and coastal erosion problems are ongoing in the map area; most notably, landslides in 2005 struck the small coastal community of La Conchita, engulfing houses and killing ten people. The Offshore of Carpinteria map area lies in the central part of the Santa Barbara littoral cell, whose littoral drift is to the east-southeast. Drift rates have been estimated to be about 400,000 tons/yr at Santa Barbara Harbor (about 15 km west of Carpinteria). At the east end of the littoral cell, eastward-moving sediment is trapped by Hueneme and Mugu Canyons and then transported to the deep-water Santa Monica Basin. Sediment supply to the western and central part of the littoral cell is largely from relatively small transverse coastal watersheds, which have an estimated cumulative annual sediment flux of 640,000 tons/yr. The much larger Ventura and Santa Clara Rivers, the mouths of which are about 25 to 30 km southeast of Carpinteria, yield an estimated 3.4 million tons of sediment annually, the coarser sediment load generally moving southeast, down the coast, and the finer sediment load moving both upcoast and offshore. The offshore part of the map area consists of a relatively flat and shallow continental shelf, which dips so gently (about 0.4° to 0.5°) that water depths at the 3-nautical-mile limit of California’s State Waters are 40 to 45 m. This part of the Santa Barbara Channel is relatively well protected from large Pacific swells from the north and northwest by Point Conception and from the south and southwest by offshore islands and banks. Fair-weather wave base is typically shallower than 20-m water depth, but winter storms are capable of resuspending fine-grained sediments in 30 m of water, and so shelf sediments in the map area probably are remobilized on an annual basis. The shelf is underlain by variable amounts of upper Quaternary shelf, estuarine, and fluvial sediments that thicken to the south. Seafloor habitats in the broad Santa Barbara Channel region consist of significant amounts of soft sediment and isolated areas of rocky habitat that support kelp-forest communities nearshore and rocky-reef communities in deep water. The potential marine benthic habitat types mapped in the Offshore of Carpinteria map area are directly related to its Quaternary geologic history, geomorphology, and active sedimentary processes. These potential habitats lie within the Shelf (continental shelf) megahabitat, dominated by a flat seafloor and substrates formed from deposition of fluvial and marine sediment during sea-level rise. This fairly homogeneous seafloor provides promising habitat for groundfish, crabs, shrimp, and other marine benthic organisms. The only significant interruptions to this homogeneous habitat type are the exposures of hard, irregular, and hummocky sedimentary bedrock and coarse-grained sediment where potential habitats for rockfish and related species exist.

California↗
USGS2017

Environmental Escherichia coli : Ecology and public health implications - A review

Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae . The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through feces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent fecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extra-intestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a fecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics provide the diversity and complexity of E. coli strains in various environments, affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments in regards to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia . The impact of environmental E. coli on water quality and public health is also discussed.

Journal of Applied Microbiology↗
USGS2020

Identification of management thresholds of urban development in support of aquatic biodiversity conservation

Urbanization degrades stream ecosystems and causes loss of bodiversity. Using benthic macroinvertebrates as a surragate for overall aquatic diversity, we conducted a series of analytical approaches to derive management thresholds of urban development designed to link ecological responses to the primary management goal of protecting aquatic diversity in streams within the Delaware Water Gap National Recreation Area (USA). We were particularly interested in identifying urban thresholds that represent the early phases of biological impact to support cost-effect management and mitigation interventions. We used taxa-specific modeling approaches within a spatially-explicit framework to develop sensitive thresholds that anticipate and demark the onset of taxa loss and provide a foundation for investigating alternative mechanisms driving biological change. We identified an early-warning threshold of 1.5% urban development in the contributing watershed where 15% of the 107 taxa evaluated exhibited significant declines in abundance but prior to any evidence of extirpation, and an extirpation threshold of 6% urban development where nearly 3% of taxa are likely to be lost locally. These thresholds of urban development are substantially lower than response thresholds typically reported based upon traditional modeling approaches that rely on spatially-implicit summaries of land cover and univariate metrics or composite indices. An analysis of ecological and functional trait composition of taxa determined to be sensitive suggests that reduced storage of benthic organic matter caused by flashier hydrographs may be the primary mechanism driving biological changes observed at relatively low levels of urbanization. Although the extent to which stream communities respond to stressor gradients in a non-linear fashion continues to be debated, we show that threshold approaches can be applied in support of aquatic resource management irrespective of whether or not stress-response functions are non-linear.

New Jersey, Pennsylvania↗
USGS2024

The influence of grazing on the spatiotemporal activity patterns of a primary sage-grouse nest predator

Perturbations in ecological processes can occur when wildlife alter their spatiotemporal activity patterns to avoid human activities that they perceive as a risk. Such perturbations can have cascading effects throughout wildlife communities. For greater sage-grouse ( Centrocercus urophasianus ; hereafter sage-grouse), nest predation plays an important role in population dynamics. Domestic cattle ( Bos taurus ) grazing has been hypothesized to increase nest predation by reducing grass height, and therefore reducing nest concealment, which may facilitate nest detection by predators. Grass height is lower on grazed pastures, but sage-grouse nest success appears similar on pastures grazed at varying intensities in several recent studies. Any reductions in nest concealment caused by grazing could potentially be offset by a localized response of one or more nest predators to the presence of cattle (i.e., the cattle avoidance hypothesis). A reduction in nest predator density or relative use within pastures could explain similar patterns of nest success on pastures grazed at varying intensities. Also, wildlife can potentially partition themselves temporally to avoid risks associated with human activities. For example, a shift in diel activity patterns by nest predators in response to cattle could result in predators being active during portions of the day when they are less efficient at locating sage-grouse nests. Thus, the effects of grazing could be offset by a temporal avoidance of cattle by predators. We deployed motion sensor cameras across six pastures to evaluate whether coyotes ( Canis latrans ; a primary sage-grouse nest predator) altered spatiotemporal activity patterns in response to cattle. We found that the probability of detecting coyotes had a positive relationship with cattle detections at camera sites (β = 0.22; 95% CI = 0.14,0.30). We also found that coyotes did not shift their diel activity patterns in response to cattle being in the pastures. Thus, in our system, similar sage-grouse nest success among pastures with different grazing intensities cannot be explained by the cattle avoidance hypothesis, at least for coyotes.

Idaho↗
USGS2020

Testing the interactive effects of flooding and salinity on tidal marsh plant productivity

Tidal wetlands support plant communities that facilitate carbon storage, accrete soil, and provide habitat for terrestrial and aquatic species. Climate change is likely to alter estuaries through sea-level rise and changing precipitation patterns, although the ecological responses are uncertain. We were interested in plant responses to physiological stress induced by elevated water salinity and flooding conditions, which may be more prevalent under climate change. . We used a greenhouse experiment and factorial flooding (1, 12, 24, and 48 % time) and salinity (0, 5, 15, 30 PSU) treatments to evaluate the productivity responses of three emergent herbaceous species ( Carex lyngbyei, Triglochin maritima, and Argentina pacifica ) common to tidal marshes of the Pacific Northwest, USA. We measured weekly changes in plant height and final above and belowground biomass for all species after 10 weeks. Increased salinity reduced final above and belowground biomass significantly in all three species, with A. pacifica responding the most, followed by C. lyngbyei and T. maritima . Increased flooding also reduced total biomass in A. pacifica and T. maritima . There was a significant response in C. lyngbyei aboveground biomass and A. pacifica height to the flooding-salinity interaction. These results indicate emergent plant community composition may change in response to novel climate conditions in estuaries, driven by distinct physiological tolerances to salinity and flooding, and highlight the importance of considering multiple climate drivers when projecting ecosystem change. This may be especially true for estuaries that currently have prolonged freshwater phases like those in the Pacific Northwest.

Aquatic Botany↗
USGS2018

Hydrological regime and climate interactively shape riparian vegetation composition along the Colorado River, Grand Canyon

Question How closely do riparian plant communities track hydrological and climatic variation in space, and how do interactions among hydrological and climatic filters influence success of flow management strategies? Location Grand Canyon, Arizona, USA. Methods Multi‐year vegetation surveys were conducted across three hydrological zones – active channel, active floodplain and inactive floodplain – within each of 42 sandbars that vary geographically in temperature and precipitation along a 400‐km river segment. Ecological niche models were used to estimate locally optimal conditions of maximum inundation duration, elevation above daily peak flow, mean annual precipitation, and mean maximum and minimum temperature for 16 of the most abundant woody and 58 most abundant herbaceous plant species. These estimates were used to calculate community‐weighted mean (CWM) environmental preferences, which were used to determine how closely vegetation preferences tracked local variation in environmental factors, and to assess interactive responses of species and communities to variation in hydrology and climate. Results Communities closely tracked hydrological variation across zones, but less so within zones. Communities tracked variation in minimum temperature more closely than maximum temperature or precipitation. At the species level, woody plants that were more abundant in wetter hydrological conditions were also more abundant in wetter climatic conditions, and vice versa. This relationship was even stronger at the community level, where there were significant negative relationships between CWM preferences of inundation duration and temperature for both woody and herbaceous vegetation. Conclusions The climate‐hydrology linkages found in this system suggest that increasing temperatures and drought are likely to reduce the inundation tolerance of riparian vegetation within the Grand Canyon. Increasing the duration of high flow events would likely reduce the abundance of encroaching woody vegetation, but could also reduce the resilience of remaining vegetation to heat waves and drought. The reinforcing effects of climatic and hydrological filters are likely to generally result in greater sensitivity of species composition to environmental change than if those environmental filters acted independently. These results have implications for predicting resource responses to environmental change, as well as prescriptions for direct vegetation management to enhance resilience.

Colorado River, Grand Canyon↗
USGS2023

Understanding ecological response to physical characteristics in side channels of a large floodplain-river ecosystem

Side channels in large floodplain rivers serve a variety of important ecological roles, particularly in reaches where habitat conditions have been degraded or diminished. We developed hypotheses regarding side channel ecological structure whereby we expected species richness of young-of-year fishes to generally be higher in shallower, more physically heterogeneous side channels with lower velocities, with differences based on reproductive guild. We also hypothesized species richness of adult fishes to be higher in side channels with greater heterogeneity that could support diverse foraging resources and provide refugia during extreme flow conditions. To test these hypotheses, we used a 28-year fish community dataset from the Upper Mississippi and Illinois Rivers. Across six study reaches, we assessed metrics of side channel physical size, heterogeneity, and connectivity that were hypothesized to explain variance of fish community response, while accounting for site-level factors across 52 side channels using multilevel models. We then used these side channel-level characteristics in a K-means cluster analysis to classify 1126 side channels across 32 reaches of the river system. Our results indicated that the relative explanatory contributions of physical metrics varied by response variable, providing varying evidence in support of our hypotheses, and indicating that different forms of heterogeneity matter in different ways. Side channel-level factors were more explanatory of fish community responses in side channels of upstream reaches compared to downstream reaches and percent wet forest was the most explanatory side channel-level factor of fish community responses across all models. Our classification of side channels indicated strong spatial contrasts in the abundance and diversity of side channels across reaches. Scaling up to understand how the diversity and abundance of different types of side channels contributes to landscape-scale ecological functions and processes would be useful for establishing targets for reach-scale physical heterogeneity.

Upper Mississippi River and Illinois River↗
USGS2009

Identifying across‐system sources of variation in a generalist freshwater fish: Correlates of total and size‐specific abundance of yellow perch

Variation in fish abundance across systems presents a challenge to our understanding of fish populations because it limits our ability to predict and transfer basic ecological principles to applied problems. Yellow perch ( Perca flavescens ) is an ideal species for exploring environmental and biotic correlates across system because it is widely distributed and physiologically tolerant. In 16 small, adjacent systems that span a wide range of environmental and biotic conditions, yellow perch were sampled with a standard suite of gear. Water quality, morphometry, vegetation, invertebrates and fish communities were concurrently measured. Multimodel inference was used to prioritise regressors for the entire yellow perch sample and three size groups (35-80, 81-180, ≥181 mm TL). Across systems, pH and fish richness were identified as the key drivers of yellow perch abundance. At very low pH (<4.0), few fish species and few yellow perch individuals were found. At ponds with moderately low pH (4.0–4.8), numbers of yellow perch increased. Ponds with high pH (>4.8) had many other species and few yellow perch. Similar patterns for pH and fish community were observed for the two largest‐size classes. Negative interactions were observed between the medium‐ and large‐sized yellow perch and between the largest and smallest yellow perch, although interspecific interactions were weaker than expected. This examination of variability for an indicator species and its component‐size classes provides ecological understanding that can help frame the larger‐scale sampling programs needed for the conservation of freshwater fish.

Ecology of Freshwater Fish↗
USGS2014

ARkStorm@Tahoe: Stakeholder perspectives on vulnerabilities and preparedness for an extreme storm event in the greater Lake Tahoe, Reno, and Carson City region

Atmospheric rivers (ARs) are strongly linked to extreme winter precipitation events in the Western U.S., accounting for 80 percent of extreme floods in the Sierra Nevada and surrounding lowlands. In 2010, the U.S. Geological Survey developed the ARkStorm extreme storm scenario for California to quantify risks from extreme winter storms and to allow stakeholders to better explore and mitigate potential impacts. To explore impacts on natural resources and communities in montane and adjacent environments, we downscaled the scenario to the greater Lake Tahoe, Reno and Carson City region of northern Nevada and California. This ArkStorm@Tahoe scenario was presented at six stakeholder meetings, each with a different geographic and subject matter focus. Discussions were facilitated by the ARkStorm@Tahoe team to identify social and ecological vulnerabilities to extreme winter storms, science and information needs, and proactive measures that might minimize impacts from this type of event. Information collected in these meetings was used to develop a tabletop emergency response exercise and set of recommendations for increasing resilience to extreme winter storm events in both Tahoe and the downstream communities of Northern Nevada. Over 300 individuals participated in ARkStorm@Tahoe stakeholder meetings and the emergency response exercise, including representatives from emergency response, natural resource and ecosystem management, health and human services, public utilities, and businesses. Interruption of transportation, communications, and lack of power and backup fuel supplies were identified as the most likely and primary points of failure across multiple sectors and geographies, as these interruptions have cascading effects on natural and human systems by impeding emergency response efforts. Other key issues that arose in discussions included contamination risks to water supplies and aquatic ecosystems, especially in the Tahoe Basin and Pyramid Lake, interagency coordination, credentialing, flood management, and coordination of health and human services during such an event. Mitigation options were identified for each of the key issues. Several science needs were identified, particularly the need for improved flood inundation maps. Finally, key lessons learned were identified and may help to increase preparedness, response and recovery from extreme storms in the future.

Report↗
USGS2008

A test of the cross-scale resilience model: Functional richness in Mediterranean-climate ecosystems

Ecological resilience has been proposed to be generated, in part, in the discontinuous structure of complex systems. Environmental discontinuities are reflected in discontinuous, aggregated animal body mass distributions. Diversity of functional groups within body mass aggregations (scales) and redundancy of functional groups across body mass aggregations (scales) has been proposed to increase resilience. We evaluate that proposition by analyzing mammalian and avian communities of Mediterranean-climate ecosystems. We first determined that body mass distributions for each animal community were discontinuous. We then calculated the variance in richness of function across aggregations in each community, and compared observed values with distributions created by 1000 simulations using a null of random distribution of function, with the same n, number of discontinuities and number of functional groups as the observed data. Variance in the richness of functional groups across scales was significantly lower in real communities than in simulations in eight of nine sites. The distribution of function across body mass aggregations in the animal communities we analyzed was non-random, and supports the contentions of the cross-scale resilience model. ?? 2007 Elsevier B.V. All rights reserved.

Ecological Complexity↗
USGS2022

What is a biocrust? A refined, contemporary definition for a broadening research community

Studies of biological soil crusts (biocrusts) have proliferated over the last few decades. The biocrust literature has broadened, with more studies assessing and describing the function of a variety of biocrust communities in a broad range of biomes and habitats and across a large spectrum of disciplines, and also by the incorporation of biocrusts into global perspectives and biogeochemical models. As the number of biocrust researchers increases, along with the scope of soil communities defined as ‘biocrust’, it is worth asking whether we all share a clear, universal, and fully articulated definition of what constitutes a biocrust. In this review, we synthesize the literature with the views of new and experienced biocrust researchers, to provide a refined and fully elaborated definition of biocrusts. In doing so, we illustrate the ecological relevance and ecosystem services provided by them. We demonstrate that biocrusts are defined by four distinct elements: physical structure, functional characteristics, habitat, and taxonomic composition. We describe outgroups, which have some, but not all, of the characteristics necessary to be fully consistent with our definition and thus would not be considered biocrusts. We also summarize the wide variety of different types of communities that fall under our definition of biocrusts, in the process of highlighting their global distribution. Finally, we suggest the universal use of the Belnap, Büdel & Lange definition, with minor modifications: Biological soil crusts (biocrusts) result from an intimate association between soil particles and differing proportions of photoautotrophic (e.g. cyanobacteria , algae , lichens , bryophytes) and heterotrophic (e.g. bacteria , fungi , archaea) organisms , which live within , or immediately on top of , the uppermost millimetres of soil. Soil particles are aggregated through the presence and activity of these often extremotolerant biota that desiccate regularly , and the resultant living crust covers the surface of the ground as a coherent layer. With this detailed definition of biocrusts, illustrating their ecological functions and widespread distribution, we hope to stimulate interest in biocrust research and inform various stakeholders (e.g. land managers, land users) on their overall importance to ecosystem and Earth system functioning.

Biological Reviews↗
USGS2005

Fire as a global ‘herbivore’: the ecology and evolution of flammable ecosystems

It is difficult to find references to fire in general textbooks on ecology, conservation biology or biogeography, in spite of the fact that large parts of the world burn on a regular basis, and that there is a considerable literature on the ecology of fire and its use for managing ecosystems. Fire has been burning ecosystems for hundreds of millions of years, helping to shape global biome distribution and to maintain the structure and function of fire-prone communities. Fire is also a significant evolutionary force, and is one of the first tools that humans used to re-shape their world. Here, we review the recent literature, drawing parallels between fire and herbivores as alternative consumers of vegetation. We point to the common questions, and some surprisingly different answers, that emerge from viewing fire as a globally significant consumer that is analogous to herbivory.

Trends in Ecology and Evolution↗
USGS2022

The hydroclimate niche: A tool for predicting and managing riparian plant community responses to streamflow seasonality

Habitat suitability is a consequence of interacting environmental factors. In riparian ecosystems, suitable plant habitat is influenced by interactions between stream hydrology and climate, hereafter referred to as “hydroclimate”. We tested the hypothesis that hydroclimate variables would improve the fit of ecological niche models for a suite of riparian species using occurrence data from the western United States. We focus on the climate conditions (temperature, precipitation and vapor pressure deficit) during the months of lowest and highest streamflow as integrative hydroclimate metrics of resource and stress levels. We found that the inclusion of hydroclimate variables improved model fit for all species in the western USA dataset. We then tested the utility of the improved habitat suitability models by projecting them onto a regulated segment of the Colorado River to assess potential impacts of streamflow seasonality on vegetation metrics of management concern. Species frequency derived from independent survey data in the Colorado River segment was significantly higher for species with predicted suitable habitat than for species without predicted suitable habitat. Under different simulated hydrographs for the Colorado River, overall species richness was predicted to be greatest with peak streamflows during summer, and native-to-non-native species ratios were predicted to be greatest with lowest streamflows in winter. Summer high flows were particularly associated with higher predicted habitat suitability for species that have increased in cover over recent decades (e.g., Pluchea sericea, Baccharis species). We conclude that hydroclimate covariates can be useful tools for predicting how riparian vegetation communities respond to changes in the seasonal timing of low and high streamflows.

River Research and Applications↗
USGS2011

Predator-induced demographic shifts in coral reef fish assemblages

In recent years, it has become apparent that human impacts have altered community structure in coastal and marine ecosystems worldwide. Of these, fishing is one of the most pervasive, and a growing body of work suggests that fishing can have strong effects on the ecology of target species, especially top predators. However, the effects of removing top predators on lower trophic groups of prey fishes are less clear, particularly in highly diverse and trophically complex coral reef ecosystems. We examined patterns of abundance, size structure, and age-based demography through surveys and collection-based studies of five fish species from a variety of trophic levels at Kiritimati and Palmyra, two nearby atolls in the Northern Line Islands. These islands have similar biogeography and oceanography, and yet Kiritimati has ∼10,000 people with extensive local fishing while Palmyra is a US National Wildlife Refuge with no permanent human population, no fishing, and an intact predator fauna. Surveys indicated that top predators were relatively larger and more abundant at unfished Palmyra, while prey functional groups were relatively smaller but showed no clear trends in abundance as would be expected from classic trophic cascades. Through detailed analyses of focal species, we found that size and longevity of a top predator were lower at fished Kiritimati than at unfished Palmyra. Demographic patterns also shifted dramatically for 4 of 5 fish species in lower trophic groups, opposite in direction to the top predator, including decreases in average size and longevity at Palmyra relative to Kiritimati. Overall, these results suggest that fishing may alter community structure in complex and non-intuitive ways, and that indirect demographic effects should be considered more broadly in ecosystem-based management.

PLoS ONE↗
USGS2019

Responses of biological soil crusts to rehabilitation strategies

Biological soil crusts (biocrusts) are common to dryland ecosystems and can influence a broad suite of soil ecological functions including stability and surface hydrology. Due to long recovery times following disturbance, there is a clear need for rehabilitation strategies to enhance the recovery of biocrust communities. Essential to biocrust recovery are exopolysaccharides (EPS): secretions comprised mainly of high molecular weight polymers that protect cyanobacteria from harsh environmental conditions. We examined whether biocrust rehabilitation strategies (inoculation in combination with surface shading and artificial soil stabilization) promote EPS production. To test if responses varied by soil texture, we measured biocrust recovery on two fine-textured soil types (clay and sandy clay loam) in a cool desert ecosystem. Shade coupled with inoculum addition resulted in the highest biocrust recovery, especially on clay soils. Independent of rehabilitation strategies, natural recovery of biocrusts occurred more rapidly on clay soils, reflected by greater increases in chlorophyll a (chl a). Chl a, a proxy for cyanobacterial biomass, was correlated to EPS amounts, suggesting that cyanobacteria are significant contributors to EPS production in biocrust development. Despite the role of EPS in biocrust establishment, EPS amounts had negligible effects on soil stability due inherent properties of fine soil texture.

Utah↗
USGS2022

Loss of phylogenetic diversity under landscape change

Habitat alteration and destruction are primary drivers of biodiversity loss. However, the evolutionary dimensions of biodiversity loss remain largely unexplored in many systems. For example, little is known about how habitat alteration/loss can lead to phylogenetic deconstruction of ecological assemblages at the local level. That is, while species loss is evident, are some lineages favored over others? Using a long-term dataset of a globally, ecologically important guild of invertebrate consumers, stream leaf “shredders,” we created a phylogenetic tree of the taxa in the regional species pool, calculated mean phylogenetic distinctiveness for >1000 communities spanning >10 year period, and related species richness, phylogenetic diversity, and distinctiveness to watershed-scale impervious cover. Using a combination of changepoint and compositional analyses, we learned that increasing impervious cover produced marked reductions in all three measures of diversity. These results aid in understanding both phylogenetic diversity and mean assemblage phylogenetic distinctiveness. Our findings indicate that, not only are species lost when there is an increase in watershed urbanization, as other studies have demonstrated, but that those lost are members of more distinct lineages relative to the community as a whole.

Science of the Total Environment↗
USGS2008

Effects of salinity on freshwater fishes in coastal plain drainages in the southeastern U.S.

This review focuses on the influence of salinity on freshwater fishes in coastal rivers and estuaries of the southeastern U.S. Influences of salinity on freshwater fish species can be explained partly through responses evidenced by behavior, physiology, growth, reproduction, and food habits during all aspects of life history. Factors influencing the rate of salinity change affect the community structure and dynamics of freshwater fishes in brackish environments. Our understanding of the relation between salinity and the life history of freshwater fishes is limited because little ecological research has been conducted in low-salinity habitats that we consider an “interface” between freshwater streams and the estuary proper. Much of the available data are descriptive in nature and describe best general patterns, but more specific studies are required to better determine the influence of salinity on freshwater fishes. Improved understanding of the influence of human-induced changes on the productivity and viability of these important systems will require a new research focus.

Reviews in Fisheries Science↗