Paul Mayer

Regenerative stormwater conveyance (RSC), a relatively new stormwater management approach, is extensively implemented throughout the mid-Atlantic for nutrient control, but little is known of its pollutant reduction capabilities and controlling factors. This study examined effects of organic carbon (C) quantity and quality on stream water quality and nutrient retention at two RSCs near Annapolis, Maryland, USA by comparing longitudinal changes in water quality at paired restored and unrestored stream reaches, and conducting lab experiments simulating RSC processes. Results showed that RSCs consistently had lower dissolved oxygen saturation (DO%) and pH relative to nearby unrestored streams, probably due to release of labile dissolved organic carbon (DOC). At one RSC, with high nitrate (NO) inputs, retention of N (16-37%) and release of DOC (18-54%) were observed with the highest retention of N during summer, and the rates of N retention and DOC release were larger than that of the ad...

Land use and climate change can accelerate the depletion of freshwater resources that support humans and ecosystem services on a global scale. Here, we briefly review studies from around the world, and highlight those in this special issue. We identify stages that characterize increasing interaction between land use and climate change. During the first stage, hydrologic modifications and the built environment amplify overland flow via processes associated with runoff-dominated ecosystems (e.g., soil compaction, impervious surface cover, drainage, and channelization). During the second stage, changes in water storage impact the capacity of ecosystems to buffer extremes in water quantity and quality (e.g., either losses in snowpack, wetlands, and groundwater recharge or gains in water and nutrient storage behind dams in reservoirs). During the third stage, extremes in water quantity and quality contribute to losses in ecosystem services and water security (e.g., clean drinking water, ...

Land cover change and stream channel loss are two related global environmental changes that are expanding and intensifying. Here, we examine how different types and transitions of land cover change impact stream channel loss across a large urbanizing watershed. We present historical land cover in the 666-km(2) Lake Thunderbird watershed in central Oklahoma (USA) over a 137year period and coinciding stream channel length changes for the most recent 70years of this period. Combining these two datasets allowed us to assess the interaction of land cover changes with stream channel loss. Over this period, the upper third of the watershed shifted from predominantly native grassland to an agricultural landscape, followed by widespread urbanization. The lower two-thirds of the watershed changed from a forested landscape to a mosaic of agriculture, urban, forest, and open water. Most channel length lost in the watershed over time was replaced by agriculture. Urban development gradually increased channel loss and disconnection from 1942 to 2011, particularly in the headwaters. Intensities of channel loss for both agriculture and urban increased over time. The two longest connected segments of channel loss came from the creation of two large impoundments, resulting in 46km and 25km of lost stream channel, respectively. Overall, the results from this study demonstrate that multiple and various land-use changes over long time periods can lead to rapid losses of large channel lengths as well as gradual (but increasing) losses of small channel lengths across all stream sizes. When these stream channel losses are taken into account, the environmental impacts of anthropogenic land-use change are compounded.

Survival was estimated for the Great Plains population of the threatened/en- dangered Piping Plover (Charadrius melodus) from resightings of 352 (214 adult, 138 juvenile) uniquely color-banded individuals in 1984-1990. One hundred one (47.2%) adults and 19 (13.8%) juveniles returned to the North Dakota study site in years after banding. Low return rates of juveniles precluded estimation of survival for that

... Medium-sized mammals, such as carnivores and lagomorphs, may spread red cedar seeds at scales approaching that of birds because of longer gut retention times and movements exceeding 1 km (Chavez-Ramirez and Slack, 1993; Chambers et al., 1999). ...

Identifying the biotic (e.g. decomposers, vegetation) and abiotic (e.g. temperature, moisture) mechanisms controlling litter decomposition is key to understanding ecosystem function, especially where variation in ecosystem structure due to successional processes may alter the strength of these mechanisms. To identify these controls and feedbacks, I measured mass loss and N flux in herbaceous, leaf, and wood litter along a successional gradient of ecosystem types (old field, transition forest, old-growth forest) while manipulating detritivore access to litter. Ecosystem type, litter type, and decomposers contributed directly and interactively to decomposition. Litter mass loss and N accumulation was higher while litter C:N remained lower in old-growth forests than in either old fields or transition forest. Old-growth forests influenced litter dynamics via microclimate (coolest and wettest) but also, apparently, through a decomposer community adapted to consuming the large standing stocks of leaf litter, as indicated by rapid leaf litter loss. In all ecosystem types, mass loss of herbaceous litter was greater than leaf litter which, in turn was greater than wood. However, net N loss from wood litter was faster than expected, suggesting localized N flux effects of wood litter. Restricting detritivore access to litter reduced litter mass loss and slowed the accumulation of N in litter, suggesting that macro-detritivores affect both physical and chemical characteristics of litter through selective grazing. These data suggest that the distinctive litter loss rates and efficient N cycling observed in old-growth forest ecosystems are not likely to be realized soon after old fields are restored to forested ecosystems.

We assessed ecosystem integrity in restored prairie wetlands in eastern South Dakota, U.S.A., by examining the relationship between and diatom diversity and production. We asked three questions: (1) Is production related to species diversity? (2) Can production-diversity relationships be used to distinguish between restored and reference wetlands with the purpose of assessing ecological integrity? (3) Are production-diversity relationships influenced by

ABSTRACT Background/Question/Methods Large river floodplains are poor nitrate pollution buffers when polluted groundwater moves beneath biogeochemically retentive zones prior to entering the main channel. However, in floodplain regions with extensive backwaters and organic carbon accumulation, surface waters may interact with groundwater to support enhanced denitrification in the subsurface and provide a sink for nitrate pollution. Here, we evaluate the spatial heterogeneity and patterns of nitrate and denitrification in the shallow groundwater of a large river floodplain to determine the controls and find predictable indicators of enhanced denitrification to better identify habitats for restoration and preservation that enhance pollution removal. Green Island, part of the Willamette River floodplain, near Coburg, Oregon is under active restoration, led by the McKenzie River Trust, to hydrologically re-connect the Willamette to its historic floodplain and re-establish native vegetation. We measured rates of denitrification using an in-situ push-pull technique with 15N isotopic tracers injected into shallow groundwater ~0.5m below the water table across the floodplain from 0.5-4m below the sediment surface. These denitrification rates, combined with quarterly sampled nutrient concentration, ambient isotopes of N and O in nitrate, and evaluation of subsurface hydrology will help identify habitats that support enhanced denitrification and guide future restoration activities in the region. Results/Conclusions Subsurface denitrification rates at Green Island span three orders of magnitude across the floodplain (Mean 57.1±17.8 µMol Kg-1D-1n=31) with the greatest rates beneath wet habitats (Max 307.7) and lowest in those areas with the greatest depth to groundwater (Min 3.65 to below detection). Denitrification rates in the subsurface are correlated negatively with elevation (ρ=-0.48 p<0.01) and positively with both dissolved organic carbon (0.45 p<0.01) and iron (0.44 p<0.01). These results suggest that obvious areas of groundwater and surface water interaction with reduced conditions, like backwater sloughs and wetlands, are indicators of subsurface denitrification and may govern subsurface processes. We found that several measures that typically indicate denitrification like enriched 15N-NO3 and N2O concentration are not correlated with measured denitrification rates, owing to the integrative nature of those measures along diverse flow paths compared to the site specificity of push-pull measurements. Based on these preliminary results, lower elevation wet regions that contribute organic carbon to the subsurface possess greater potential to denitrify nitrate at Green Island and are an indicator of a potentially valuable nitrate sink in floodplain restoration. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.

Understanding the connection between road salts and water quality is essential to assess the implications for human health and ecosystem services. To assess the effects of the restoration on water quality, surface and ground water have been monitored at Minebank Run, MD since 2001. Stream gauges and piezometers were installed in the stream channel and floodplain of Minebank Run along multiple transects above and below the I-695 Beltway. In our preliminary data analysis, we found a trend of increasing salt concentrations downstream of the Beltway in the surface water. This downstream site also has significantly greater surface water salinity than upstream of the Beltway. Ground water salt concentrations suggest that the ground water acts as a continuous source of salts to the surface water. The potential for road salt deicers to impact stream restoration efforts by increasing salinity levels in urbanizing watersheds will be discussed along with the possibility for drinking water impacts.

Friday, August 7, 2009 - 8:40 AM COS 125-3: Low elevation inland habitats of the Willamette River floodplain support enhanced denitrification. Kenneth J. Forshay, Barton R. Faulkner, Paul Mayer, and Steven P. Cline. United States Environmental Protection Agency. ...

We assessed ecosystem integrity in restored prairie wetlands in eastern South Dakota, U.S.A., by examining the relationship between and diatom diversity and production. We asked three questions: (1) Is production related to species diversity? (2) Can production-diversity relationships be used to distinguish between restored and reference wetlands with the purpose of assessing ecological integrity? (3) Are production-diversity relationships influenced by

In the Baltimore Ecosystem Study, one of two urban long-term ecological research (LTER) projects funded by the U.S. National Science Foundation, we are using "the watershed approach" to integrate ecological, physical and social sciences. Watersheds are a natural (and well-used) physical unit for ecological research and can also function as a focus for human-environment interactions. Suburban watershed input/output budgets for nitrogen (N) have shown surprisingly high retention which has led to detailed analysis of sources and sinks in these watersheds. Home lawns, thought to be a major source of N in suburban watersheds have more complex coupled carbon (C) and N dynamics than previously thought, and are likely the site of much N retention. Levels of soil organic matter, microbial biomass and respiration are similar in home lawns and forests, leading to relatively low inorganic N pools in soil and low hydrologic losses of inorganic N from lawns. Riparian zones, thought to be an important sink for N in many watersheds, have turned out be N sources in urban watersheds due to hydrologic changes that disconnect streams from their surrounding landscape. High storm flows lead to stream incision which lowers riparian water tables which stimulates aerobic production (nitrification) and decreases anaerobic consumption (denitrification) of inorganic N. In-stream processing of N is also affected by these hydrologic changes, with important effects (both positive and negative) on retention. Geomorphic stream restoration designed to reverse structural degradation caused by urban runoff can increase in-stream retention by creating features with high denitrification potential. Organic debris dams and hyporheic zones exposed to nitrate-rich stream water can function as hotspots of denitrification in restored streams. Considering human goals in stream restoration can help to establish connections between people and streams, which can lead to improvements in water quality as people become monitors and advocates for stream ecosystem integrity. Creating positive feedbacks between ecological restoration and human preferences can be key for achieving specific biogeosociochemical goals in urban and suburban watersheds.