Geology topics

E. S. Bernhardt

Publications and source records attributed to E. S. Bernhardt.

3 recordsLinked to original sources

USGS2018

Understanding how microbiomes influence the systems they inhabit

Translating the ever-increasing wealth of information on microbiomes (environment, host, or built environment) to advance the understanding of system-level processes is proving to be an exceptional research challenge. One reason for this challenge is that relationships between characteristics of microbiomes and the system-level processes they influence are often evaluated in the absence of a robust conceptual framework and reported without elucidating the underlying causal mechanisms. The reliance on correlative approaches limits the potential to expand the inference of a single relationship to additional systems and advance the field. We propose that research focused on how microbiomes influence the systems they inhabit should work within a common framework and target known microbial processes that contribute to the system-level processes of interest. Here we identify three distinct categories of microbiome characteristics (microbial processes, microbial community properties, and microbial membership) and propose a framework to empirically link each of these categories to each other and the broader system level processes they affect. We posit that it is particularly important to distinguish microbial community properties that can be predicted from constituent taxa (community aggregated traits) from and those properties that are currently unable to be predicted from constituent taxa (emergent properties). Existing methods in microbial ecology can be applied to more explicitly elucidate properties within each of these categories and connect these three categories of microbial characteristics with each other. We view this proposed framework, gleaned from a breadth of research on environmental microbiomes and ecosystem processes, as a promising pathway with the potential to advance discovery and understanding across a broad range of microbiome science.

Nature Microbiology↗

USGS2012

The interactive effects of excess reactive nitrogen and climate change on aquatic ecosystems and water resources of the United States

Nearly all freshwaters and coastal zones of the US are degraded from inputs of excess reactive nitrogen (Nr), sources of which are runoff, atmospheric N deposition, and imported food and feed. Some major adverse effects include harmful algal blooms, hypoxia of fresh and coastal waters, ocean acidification, long-term harm to human health, and increased emissions of greenhouse gases. Nitrogen fluxes to coastal areas and emissions of nitrous oxide from waters have increased in response to N inputs. Denitrification and sedimentation of organic N to sediments are important processes that divert N from downstream transport. Aquatic ecosystems are particularly important denitrification hotspots. Carbon storage in sediments is enhanced by Nr, but whether carbon is permanently buried is unknown. The effect of climate change on N transport and processing in fresh and coastal waters will be felt most strongly through changes to the hydrologic cycle, whereas N loading is mostly climate-independent. Alterations in precipitation amount and dynamics will alter runoff, thereby influencing both rates of Nr inputs to aquatic ecosystems and groundwater and the water residence times that affect Nr removal within aquatic systems. Both infrastructure and climate change alter the landscape connectivity and hydrologic residence time that are essential to denitrification. While Nr inputs to and removal rates from aquatic systems are influenced by climate and management, reduction of N inputs from their source will be the most effective means to prevent or to minimize environmental and economic impacts of excess Nr to the nation’s water resources.

Biogeochemistry↗

USGS2007

River and riparian restoration in the southwest: Results of the National River Restoration Science Synthesis project

Restoration activity has exponentially increased across the Southwest since 1990. Over 37,000 records were compiled into the National River Restoration Science Synthesis (NRRSS) database to summarize restoration trends and assess project effectiveness. We analyzed data from 576 restoration projects in the Southwest (NRRSS-SW). More than 50% of projects were less than or equal to 3 km in length. The most common restoration project intent categories were riparian management, water quality management, in-stream habitat improvement, and flow modification. Common project activities were well matched to goals. Conservative estimates of total restoration costs exceeded $500 million. Most restoration dollars have been allocated to flow modification and water quality management. Monitoring was linked to 28% of projects across the Southwest, as opposed to just 10% nationwide. Mean costs were statistically similar whether or not projects were monitored. Results from 48 telephone interviews provided validation of NRRSS-SW database analyses but showed that project costs are often underreported within existing datasets. The majority of interviewees considered their projects to be successful, most often based upon observed improvements to biota or positive public reaction rather than evaluation of field data. The efficacy of restoration is difficult to ascertain given the dearth of information contained within most datasets. There is a great need for regional entities that not only track information on project implementation but also maintain and analyze monitoring data associated with restoration. Agencies that fund or regulate restoration should reward projects that emphasize monitoring and evaluation as much as project implementation. ?? 2007 Society for Ecological Restoration International.

Restoration Ecology↗