Glenn Guntenspergen, Ph.D.
Science and Products
The Challenge: Accelerations in sea-level rise and changing environmental stressors have important implications for the integrity of coastal wetlands and for efforts to restore and protect the ecosystem services they provide. Their persistence and adaptation to these stressors depends on the net effects of changes in physical processes and biotic responses. Future planning by decision makers will require scientifically sound forecasts of potential impacts, knowledge of sea-level rise thresholds, and indications of the potential effectiveness of various adaptation strategies.
The Challenge: The integrity and sustainability of salt marshes in National Park units of the Northeast Coastal and Barrier Network (NCBN) are severely threatened by human activities. These marshes provide critical fish and wildlife habitat and essential ecosystem services in the northeastern coastal zone, and are a high priority for NCBN Vital Signs monitoring. Biennial monitoring of nekton (i.e., fish and free-swimming crustaceans) and vegetation has been conducted in NCBN parks since 2008. There is now a critical need for tools to integrate Vital Signs measures in a way that allows assessment of the overall condition of park salt marshes.
The Challenge: The high winds and storm surge associated with Hurricane Sandy impacted coastal wetlands from Virginia to Maine. Understanding the ecological and geological impacts of hurricanes on coastal wetlands and their interactive effects with local conditions is important for identifying resilience of these communities to predicted global sea-level rise. Given the projected increase in number and intensity of hurricanes, we need to understand the impact of physical and chemical stressors associated with hurricanes in order to efficiently and effectively protect and restore these critical habitats. Storm-related sediment deposition and erosion are two of the potential long-term impacts of severe storms such as Hurricane Sandy on marsh surface elevation and resilience. But wetland impacts are unique for every major storm because of each storm’s unique characteristics (wind speed, angle of approach, tidal stage).
We measured the response of plants to disturbance across a gradient in inundation times by transplanting tussocks of Schoenoplectus americanus into mesocosms of different elevation in two marsh organ platforms.
This dataset is comprised of eight files related to salt marsh monitoring data or measures of of human disturbance (i.e. human impacts in terms of physical, chemical, and land-use stressors) collected at 33 marsh study units (MSUs) in five National Parks within the NPS Northeast Coastal and Barrier Network (NCBN) along the NE coast of the US.
Balanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes
Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes...Rosencranz, Jordan A.; Ganju, Neil K.; Ambrose, Richard F.; Brosnahan, Sandra M.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; MacDonald, Glen M.; Takekawa, John Y.; Thorne, Karen M.
Effects of climate change on tidal marshes along a latitudinal gradient in California
Public SummaryThe coastal region of California supports a wealth of ecosystem services including habitat provision for wildlife and fisheries. Tidal marshes, mudflats, and shallow bays within coastal estuaries link marine, freshwater and terrestrial habitats, and provide economic and recreational benefits to local communities. Climate change...Thorne, Karen M.; MacDonald, Glen M.; Ambrose, Rich F.; Buffington, Kevin J.; Freeman, Chase M.; Janousek, Christopher N.; Brown, Lauren N.; Holmquist, James R.; Guntenspergen, Glenn R.; Powelson, Katherine W.; Barnard, Patrick L.; Takekawa, John Y.
Potential effects of sea-level rise on plant productivity: Species-specific responses in northeast Pacific tidal marshes
Coastal wetland plants are adapted to varying degrees of inundation. However, functional relationships between inundation and productivity are poorly characterized for most species. Determining species-specific tolerances to inundation is necessary to evaluate sea-level rise (SLR) effects on future marsh plant community composition, quantify...Janousek, Christopher; Buffington, Kevin J.; Thorne, Karen M.; Guntenspergen, Glenn R.; Takekawa, John Y.; Dugger, Bruce D.
Overestimation of marsh vulnerability to sea level rise
Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sea level rise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or...Kirwan, Matthew L.; Temmerman, Stijn; Skeehan, Emily E.; Guntenspergen, Glenn R.; Fagherazzi, Sergio
Greenhouse gas fluxes from salt marshes exposed to chronic nutrient enrichment
We assessed the impact of nutrient additions on greenhouse gas fluxes using dark static chambers in a microtidal and a macrotidal marsh along the coast of New Brunswick, Canada approximately monthly over a year. Both were experimentally fertilized for six years with varying levels of N and P. For unfertilized, N and NPK treatments, average yearly...Chmura, Gail L.; Kellman, Lisa; van Ardenne, Lee; Guntenspergen, Glenn R.
Impacts of climate change on land-use and wetland productivity in the Prairie Pothole Region of North America
Wetland productivity in the Prairie Pothole Region (PPR) of North America is closely linked to climate. A warmer and drier climate, as predicted, will negatively affect the productivity of PPR wetlands and the services they provide. The effect of climate change on wetland productivity, however, will not only depend on natural processes (e.g.,...Rashford, Benjamin S.; Adams, Richard M.; Wu, JunJie; Voldseth, Richard A.; Guntenspergen, Glenn R.; Werner, Brett; Johnson, W. Carter
Non-linear responses of glaciated prairie wetlands to climate warming
The response of ecosystems to climate warming is likely to include threshold events when small changes in key environmental drivers produce large changes in an ecosystem. Wetlands of the Prairie Pothole Region (PPR) are especially sensitive to climate variability, yet the possibility that functional changes may occur more rapidly with warming than...Johnson, W. Carter; Werner, Brett; Guntenspergen, Glenn R.
Sediment transport-based metrics of wetland stability
Despite the importance of sediment availability on wetland stability, vulnerability assessments seldom consider spatiotemporal variability of sediment transport. Models predict that the maximum rate of sea level rise a marsh can survive is proportional to suspended sediment concentration (SSC) and accretion. In contrast, we find that SSC and...Ganju, Neil K.; Kirwan, Matthew L.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; Cahoon, Donald R.; Kroeger, Kevin D.
Response of plant productivity to experimental flooding in a stable and a submerging marsh
Recent models of tidal marsh evolution rely largely on the premise that plants are most productive at an optimal flooding regime that occurs when soil elevations are somewhere between mean sea level and mean high tide. Here, we use 4 years of manipulative “marsh organ” flooding experiments to test the generality of this conceptual...Kirwan, Matthew L.; Guntenspergen, Glenn R.
Use of structured decision making to identify monitoring variables and management priorities for salt marsh ecosystems
Most salt marshes in the USA have been degraded by human activities, and coastal managers are faced with complex choices among possible actions to restore or enhance ecosystem integrity. We applied structured decision making (SDM) to guide selection of monitoring variables and management priorities for salt marshes within the National Wildlife...Neckles, Hilary A.; Lyons, James E.; Guntenspergen, Glenn R.; Shriver, W. Gregory; Adamowicz, Susan C.
Connecting the dots: a collaborative USGS-NPS effort to expand the utility of monitoring data
The Natural Resource Challenge (National Park Service 1999) was a call to action. It constituted a mandate for monitoring based on the twin premises that (1) natural resources in national parks require active management and stewardship if we are to protect them from gradual degradation, and (2) we cannot protect what we do not understand. The...Grace, James B.; Schoolmaster, Donald R.; Schweiger, E. William; Mitchell, Brian R.; Miller, Kathryn; Guntenspergen, Glenn R.
Threshold concepts: implications for the management of natural resources
Threshold concepts can have broad relevance in natural resource management. However, the concept of ecological thresholds has not been widely incorporated or adopted in management goals. This largely stems from the uncertainty revolving around threshold levels and the post hoc analyses that have generally been used to identify them. Natural...Guntenspergen, Glenn R.; Gross, John