<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Hardison, Amber K.</style></author><author><style face="normal" font="default" size="100%">Canuel, E.</style></author><author><style face="normal" font="default" size="100%">Tobias, C.R.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Veuger, B.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Carbon and nitrogen dynamics in shallow photic systems: Interactions between macroalgae, microalgae, and bacteria</style></title><secondary-title><style face="normal" font="default" size="100%">Limnology &amp; Oceanography</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2011</style></year></dates><volume><style face="normal" font="default" size="100%">56</style></volume><pages><style face="normal" font="default" size="100%">1489-1503</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><issue><style face="normal" font="default" size="100%">4</style></issue><accession-num><style face="normal" font="default" size="100%">LTER.2011-86148</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Hardison, A</style></author><author><style face="normal" font="default" size="100%">Tobias, C</style></author><author><style face="normal" font="default" size="100%">Stanhope, J. W.</style></author><author><style face="normal" font="default" size="100%">Canuel, E.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">An experimental apparatus for laboratory and field-based perfusion of sediment porewater with dissolved tracers</style></title><secondary-title><style face="normal" font="default" size="100%">Estuaries and Coasts</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2011</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">DOI 10.1007/s12237-010-9285-2</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">34</style></volume><pages><style face="normal" font="default" size="100%">243-255</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2011-85874</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Giordano, J. P.</style></author><author><style face="normal" font="default" size="100%">Brush, M. J.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Quantifying annual nitrogen loads to Virginias coastal lagoons: sources and water quality response</style></title><secondary-title><style face="normal" font="default" size="100%">Estuaries and  Coasts</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2011</style></year></dates><volume><style face="normal" font="default" size="100%">34</style></volume><pages><style face="normal" font="default" size="100%">297-309</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2011-87103</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>5</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Christian, Robert R.</style></author><author><style face="normal" font="default" size="100%">Camacho-Ibar, V.</style></author><author><style face="normal" font="default" size="100%">Voss, C. M.</style></author><author><style face="normal" font="default" size="100%">Bondavalli, C.</style></author><author><style face="normal" font="default" size="100%">Viaroli, P.</style></author><author><style face="normal" font="default" size="100%">Naldi, M.</style></author><author><style face="normal" font="default" size="100%">Tyler, A. Christy</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">McGlathery, K. J.</style></author><author><style face="normal" font="default" size="100%">Ulanowicz, R. E.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Paerl, H.</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Ecosystem Health Indexed through Networks of Nitrogen Cycling</style></title><secondary-title><style face="normal" font="default" size="100%">Coastal Lagoons: Critical Habitats of Environmental Change</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2010</style></year></dates><publisher><style face="normal" font="default" size="100%">Taylor &amp; Francis Group LLC.</style></publisher><pub-location><style face="normal" font="default" size="100%">Boca Raton, FL</style></pub-location><pages><style face="normal" font="default" size="100%">73-91</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2010-85869</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Hardison, Amber K.</style></author><author><style face="normal" font="default" size="100%">Canuel, E. A.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Veuger, B.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Fate of macroalgae in benthic systems: carbon and nitrogen cycling within the microbial community</style></title><secondary-title><style face="normal" font="default" size="100%">Mar. Ecol. Prog. Ser.</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2010</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">doi:10.3354/meps08720</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">414</style></volume><pages><style face="normal" font="default" size="100%">41-55</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2010-85875</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>5</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Stanhope, J. W.</style></author><author><style face="normal" font="default" size="100%">Hardison, Amber K.</style></author><author><style face="normal" font="default" size="100%">McGlathery, K. J.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Paerl, H.</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Sources and Fates of Nitrogen in Virginia Coastal Bays</style></title><secondary-title><style face="normal" font="default" size="100%">Coastal Lagoons: Critical Habitats of Environmental Change</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2010</style></year></dates><publisher><style face="normal" font="default" size="100%">CRC Press</style></publisher><pub-location><style face="normal" font="default" size="100%">Boca Raton FL</style></pub-location><pages><style face="normal" font="default" size="100%">43-72</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2010-85852</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Stanhope, J. W.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Reay, William G.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Base Flow Nutrient Discharges from Lower Delmarva Peninsula Watersheds of Virginia, USA.</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Environmental Quality</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year></dates><volume><style face="normal" font="default" size="100%">38</style></volume><pages><style face="normal" font="default" size="100%">2070-2083</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2009-82622</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>5</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Joye, S. B.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Mjulholland, M.</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Nitrogen cycling in Estuarine and Nearshore Sediments</style></title><secondary-title><style face="normal" font="default" size="100%">Nitrogen in the Marine Environment</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2008</style></year></dates><publisher><style face="normal" font="default" size="100%">Springer Verlag</style></publisher><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Nitrogen (N) availability is frequently cited as the factor limiting primary production in marine systems over annual time scales (Capone and Kiene, 1988; Ryther and Dunstan, 1971; Vitousek and Howarth, 1991) though phosphorus (P), silica (Si) limitation or co-limitation by N, P, and/or Si sometimes occur on seasonal time scales (Conley et al., 1993; Malone et al., 1996; Officer and Ryther, 1980). In offshore waters, the presence of bioavailable iron can also regulate primary productivity, particularly that by diatoms (Coale et al., 1996; Hutchins and Bruland, 1998; Martin et al., 1994). Sediment N pools reflect a balance between inputs (external or internal) and outputs (sedimentation, denitrification (DNF), long-term burial, or export), and this balance is affected by a variety of environmental and physiological factors ( Joye, 2002). Within the sediment, N is cycled primarily by microbiallymediated redox reactions between more highly oxidized forms (nitrate, NO3, or nitrite, NO2) and more reduced forms (ammonium, NH4</style></abstract><accession-num><style face="normal" font="default" size="100%">LTER.2008-82601</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Aranibar, J. N.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Epstein, H. E.</style></author><author><style face="normal" font="default" size="100%">Feral, C. J. W.</style></author><author><style face="normal" font="default" size="100%">Swap, R. J.</style></author><author><style face="normal" font="default" size="100%">Ramontso, J.</style></author><author><style face="normal" font="default" size="100%">Stephen  Macko,</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Nitrogen isotope composition of soils, C3 and C4 plants along land use gradients in southern Africa</style></title><secondary-title><style face="normal" font="default" size="100%">J. Arid Environ.</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2008</style></year></dates><volume><style face="normal" font="default" size="100%">72</style></volume><pages><style face="normal" font="default" size="100%">326-337</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2008-82592</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">McGlathery, K. J.</style></author><author><style face="normal" font="default" size="100%">Sundback, K.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Eutrophication in shallow coastal bays and lagoons: the role of plants in the coastal filter</style></title><secondary-title><style face="normal" font="default" size="100%">Marine Ecology-Progress Series</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">&lt;Go to ISI&gt;://000251203500001</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">348</style></volume><pages><style face="normal" font="default" size="100%">1-18</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2007-60549</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Neubauer, Scott C.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Neikirk, B. B.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Nitrogen cycling and ecosystem exchanges in a Virginia tidal freshwater marsh.</style></title><secondary-title><style face="normal" font="default" size="100%">Estuaries</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2005</style></year></dates><volume><style face="normal" font="default" size="100%">28</style></volume><pages><style face="normal" font="default" size="100%">909-922</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Tidal freshwater marshes are diverse habitats that differ both within and between marshes in terms of plant community composition, sediment type, marsh elevation, and nutrient status. Because our knowledge of the nitrogen (N) biogeochemistry of tidal freshwater systems is limited, it is difficult to assess how these marshes will respond to long-term progressive nutrient loading due to watershed development and urbanization. We present a process-based mass balance model of N cycling in Sweet Hall marsh, a pristine (i.e., low nutrient) Peltandra virginica-Pontederia cordata dominated tidal freshwater marsh in the York River estuary, Virginia. The model, which was based on a combination of field and literature data, revealed that N cycling in the system was largely conservative. The mineralization of organic N to NH4+ provided almost twice as much inorganic N as was needed to support marsh macrophyte and benthic microalgal primary production. Efficient utilization of porewater NH4+ by nitrifiers and other microbes resulted in low rates of tidal NH4+ export from the marsh and little accumulation of NH4+ in marsh porewaters. Inputs of N from the estuary and atmosphere were not critical in supporting marsh primary production, and served to balance N losses due to denitrification and burial. A comparison of these results with the literature suggests that the relative importance of tidal freshwater marsh N cycling processes, including plant productivity, organic matter mineralization, microbial immobilization, and coupled nitrification-denitrification, are largely independent of small changes in water column N loading. Although very high (millimolar) concentrations of dissolved inorganic N can affect processes including denitrification and plant productivity, the factors that cause the switch from efficient N recycling to a more open N cycle have not yet been identified</style></abstract><accession-num><style face="normal" font="default" size="100%">LTER.2005-82611</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>5</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">McGlathery, K. J.</style></author><author><style face="normal" font="default" size="100%">Sundback, K.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Pedersen, M. F.</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">The importance of pimary producers for benthic N and P cycling</style></title><secondary-title><style face="normal" font="default" size="100%">The Influence of Primary Producers on Estuarine Nutrient Cycling</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2004</style></year></dates><publisher><style face="normal" font="default" size="100%">Klluwer Academic Publishers</style></publisher><pages><style face="normal" font="default" size="100%">232-263</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2004-60548</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Tyler, A Christy.</style></author><author><style face="normal" font="default" size="100%">McGlathery, I. C.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Benthic algae control sediment-water column fluxes of organic and inorganic  nitrogen compounds in a temperate lagoon.</style></title><secondary-title><style face="normal" font="default" size="100%">Limnology and Oceanography</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2003</style></year></dates><volume><style face="normal" font="default" size="100%">48</style></volume><pages><style face="normal" font="default" size="100%">2125-2137</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2003-49288</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">McGlathery, K. J.</style></author><author><style face="normal" font="default" size="100%">Tyler, A Christy.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Microbial mediation of reactive nitrogen transformations in a temperate lagoon</style></title><secondary-title><style face="normal" font="default" size="100%">Marine Ecology-Progress Series</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2003</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">&lt;Go to ISI&gt;://000181085100005</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">246</style></volume><pages><style face="normal" font="default" size="100%">73-84</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Coastal lagoons positioned along the land margin may play an important role in removing or transforming reactive nitrogen during its transport from land to the ocean. Hog Island Bay is a shallow, coastal lagoon located on the ocean-side of the Delmarva Peninsula in Virginia (USA). External nitrogen inputs are derived primarily from agriculturally enriched groundwater, and these support, in part, the high production of benthic macroalgae and microalgae as the dominant primary producers. This study focuses on processes in the water column (phytoplankton and bacterial) and in the sediments (microalgal and bacterial) responsible for transformations of dissolved inorganic and organic nitrogen (N). Sediment-water exchanges of dissolved inorganic and organic N were measured as well as sediment gross and net mineralization of organic N. Net changes in dissolved inorganic nitrogen concentrations were greater in the water-column incubations than in the incubations including sediment and water. In the water column, metabolism resulted in net uptake of NH4+ during all seasons and in net uptake of NO3- during most seasons. In the sediments, gross mineralization, which ranged from 0.9 to 6.5 mmol N m(-2) d(-1), resulted in short turnover times (&lt; 1 d) for the sediment NH4+ pool; however, sediment-water fluxes of both NH4+ and NO3- were either negligible or directed into the sediments. The NH4+ produced by gross mineralization was rapidly consumed in the dark. Biological processes potentially responsible for removal of sediment NH4+ and NO3- include coupled nitrification- denitrification, dark uptake by benthic microalgae, and immobilization by heterotrophic bacteria. In the absence of dark uptake of NH4+ by benthic microalgae, potential nitrification calculated as the difference between gross mineralization and NH4+ fluxes, would range from 1.5 to 6.4 mmol N m(-2) d(-1), similar to rates observed in a range of other systems. Similarly, potential denitrification rates estimated as the difference between calculated nitrification rates and measured NO3- fluxes would vary from 1.88 to 5.16 mol N m(-2) d(-1) and fall within the range of rates reported for similar systems. However, since calculated benthic microalgal N demand (2.51 to 16.11 mmol N m(-2) d(-1)) exceeded NH4+ release by gross mineralization at all sites and during all seasons, this suggests that dark benthic microalgal uptake was likely to be an important sink for mineralized N. Finally, sediment bacterial N immobilization may also be important given the relatively high C/N of sediment organic matter. These estimates of the potential consumptive processes for mineralized sediment N indicate that the lagoon is likely to retard and or remove reactive N during its transport to the coastal ocean.</style></abstract><accession-num><style face="normal" font="default" size="100%">LTER.2003-48871</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Kopacek, J.</style></author><author><style face="normal" font="default" size="100%">Stuchlik, E.</style></author><author><style face="normal" font="default" size="100%">Vesely, J.</style></author><author><style face="normal" font="default" size="100%">Schaumburg, J.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Fott, J.</style></author><author><style face="normal" font="default" size="100%">Hejzlar, J.</style></author><author><style face="normal" font="default" size="100%">Vrba, J.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Hysteresis in reversal of Central European mountain lakes from atmospheric acidification</style></title><secondary-title><style face="normal" font="default" size="100%">Water, Air, and Soil Pollution</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year></dates><volume><style face="normal" font="default" size="100%">2</style></volume><pages><style face="normal" font="default" size="100%">91-114</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><issue><style face="normal" font="default" size="100%">2</style></issue><accession-num><style face="normal" font="default" size="100%">LTER.2002-49078</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Neubauer, Scott C.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Constantine, J. A.</style></author><author><style face="normal" font="default" size="100%">Kuehl, S. A.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Sediment deposition and accretion in a mid-Atlantic (U.S.A) tidal freshwater marsh</style></title><secondary-title><style face="normal" font="default" size="100%">Estuarine Coastal and Shelf Science</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year></dates><volume><style face="normal" font="default" size="100%">54</style></volume><pages><style face="normal" font="default" size="100%">713-727</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2002-49125</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Miller, W D.</style></author><author><style face="normal" font="default" size="100%">Neubauer, Scott C.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Effects of sea level induced disturbances on high salt marsh metabolism</style></title><secondary-title><style face="normal" font="default" size="100%">Estuaries</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><volume><style face="normal" font="default" size="100%">24</style></volume><pages><style face="normal" font="default" size="100%">357-367</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The rate of sea-level rise is predicted to increase as a result of global warming. As sea level rises there will also be an increase in frequency and duration of disturbances associated with higher sea level. Salt marshes, which provide a transition between the aquatic and terrestrial environments around much of the temperate world, will be the first to feel the effects of an increased rate of sea-level rise. This study examines the metabolic response of a high salt marsh to the disturbances of increased inundation and wrack deposition that are associated with sea-level rise. We measured changes in community and sediment photosynthesis and respiration by analyzing carbon dioxide fluxes in the light and dark. Data from the seasonal flux measurements were combined with continuously measured light and temperature data to develop a model that estimated annual production and respiration. Results suggest that increased inundation will reduce both production and respiration and yield a moderate net loss of organic carbon to the high marsh. The model also predicts a substantial loss of organic carbon to wrack affected areas. The consequence of decreased organic carbon input to the marsh is a reduced ability to accrete material, which is necessary in order to maintain elevation relative to sea level.</style></abstract><accession-num><style face="normal" font="default" size="100%">LTER.2001-49109</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Tyler, A Christy.</style></author><author><style face="normal" font="default" size="100%">McGlathery, K. J.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Macroalgae mediation of dissolved organic nitrogen fluxes in a temperate coastal lagoon</style></title><secondary-title><style face="normal" font="default" size="100%">Estuarine Coastal and Shelf Science</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">&lt;Go to ISI&gt;://000171125500004</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">53</style></volume><pages><style face="normal" font="default" size="100%">155-168</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The activity of the benthos, including benthic plants, is important in driving the overall system dynamics in shallow lagoons, due to the high ratio of sediment surface area relative to water volume. In Hog Island Bay, benthic macroalgae appear to be a key regulator of DON dynamics, both while alive and following senescence. We investigated the role of macroalgae in mediating water column concentrations and sediment-water column fluxes of DON across a nutrient gradient in Hog Island Bay, a shallow macroalgal-dominated back-barrier lagoon located on the Virginia Coast. Sediment-water column exchanges of DON, urea and DIN were measured in sediment cores with and without macroalgae (Ulva lactuca) at three subtidal sites from the mainland to the barrier islands in the fall of 1997 and the spring and summer of 1998. The summer sampling dates bracketed a large macroalgal bloom in the mid-lagoon. Dissolved organic nitrogen was an important component (52-98%) of the total dissolved nitrogen pool in Hog Island Bay waters and made up the majority of the sediment N flux to the water column. Macroalgae impacted benthic-pelagic coupling by preventing diffusion of DIN from the water column to the sediments and by intercepting urea fluxes from the sediment to the water column. Closest to the mainland and closest to the barrier islands, at sites with low macroalgal biomass, sediment-water column fluxes of DIN and urea-free DON were negligible or directed into the sediments. Fluxes of urea from the sediment to the water column were significant at both sites, and may play an important role in satisfying macroalgal N demand, especially at the low N island site. Overall, urea was 32% of the mean DON flux from the sediments to the water column. Fluxes of urea-free DON were highest in the mid-lagoon, where macroalgal biomass was highest. The highest overall flux rates of DON (&gt;38 mmol m(-2) d(-1)) and DIN (&gt; 33 mmol m(-2) d(-1)) were measured following an isolated crash of a large macroalgal mat. These release rates were not sustained for long, however, and we estimated that the majority of the N contained in the decomposing macroalgal tissues disappeared in &lt;2 weeks. In addition to release of organic N following senescence, macroalgae leak DON into the water column during active growth; release of DON increased by 250% in cores incubated with U. lactuca relative to cores with sediment only. These algae function as a conduit whereby water-column DIN and sediment urea are taken up and released to the water column as DON over relatively short (hours) time scales. This conversion of bioavailable dissolved N to PON and DON by macroalgae is likely to be important to overall system metabolism and to the retention of N within the lagoon. (C) 2001 Academic Press.</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><accession-num><style face="normal" font="default" size="100%">LTER.2001-49286</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">McGlathery, K. J.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Tyler, A Christy.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Magnitude and variability of benthic and pelagic metabolism in a temperate coastal lagoon</style></title><secondary-title><style face="normal" font="default" size="100%">Marine Ecology-Progress Series</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">&lt;Go to ISI&gt;://000170395500001</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">216</style></volume><pages><style face="normal" font="default" size="100%">1-15</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">In shallow coastal systems where most of the seafloor lies within the photic zone, benthic photoautotrophy is likely to play a key role in regulating carbon and nitrogen cycling. We measured dissolved inorganic carbon exchanges in seasonal microcosm incubations to determine the relative importance of benthic (with and without macroalgae) and water column metabolism at 3 sites located along a nutrient gradient in a coastal barrier-island lagoon on the eastern shore of Virginia. When coupled with data on in situ biomass, the incubations clearly indicated a seasonality in the dominance of primary producers at the sites, with benthic primary producers being the most important early and late in the growing season and phytoplankton dominating following a mid-summer period of macroalgal decay and the release of algal-bound nutrients to the water column. The benthos was always net autotrophic, and differences in community metabolism at the 3 sites appeared to be largely due to variation in macroalgal biomass, Macroalgae accumulated to a greater extent in the mid-lagoon and accounted for up to 96 % of benthic production. The water column was net heterotrophic throughout the lagoon except following the mid- summer macroalgal collapse, when phytoplankton biomass was highest at the 2 sites closest to the mainland, Benthic microalgal production also increased in importance following the macroalgal decline, suggesting that competition for light and possibly nutrients limited benthic microalgal production when macroalgal densities were high. Overall, there was a distinct seasonality in patterns of total metabolism within the bay, where all sites were net autotrophic in the spring and summer and net heterotrophic in the fall. Up to 8 g N m(-2) accumulated in macroalgal biomass throughout spring and early summer at the mid-lagoon shoal site, slowing nutrient transport through the lagoon. Nutrient turnover rates were higher during the period when phytoplankton and benthic microalgae were the dominant primary producers. This study illustrates the functional importance of different primary producer communities to carbon metabolism and to the temporary retention of nutrients in lagoonal land-margin ecosystems.</style></abstract><accession-num><style face="normal" font="default" size="100%">LTER.2001-49102</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Tobias, C.R.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Canuel, E. A.</style></author><author><style face="normal" font="default" size="100%">Stephen  Macko,</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Nitrogen cycling through a fringing marsh-aquifer ecotone</style></title><secondary-title><style face="normal" font="default" size="100%">Marine Ecology Progress Series</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><volume><style face="normal" font="default" size="100%">210</style></volume><pages><style face="normal" font="default" size="100%">25-39</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2001-49276</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Tobias, C.R.</style></author><author><style face="normal" font="default" size="100%">Harvey, J.W.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Quantifying  groundwater discharge through fringing wetlands to estuaries:  Seasonal variability, methods comparison, and implications for  wetland-estuary exchange</style></title><secondary-title><style face="normal" font="default" size="100%">Limnology and Oceanography</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><volume><style face="normal" font="default" size="100%">46</style></volume><pages><style face="normal" font="default" size="100%">604-615</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2001-49277</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Tobias, C.R.</style></author><author><style face="normal" font="default" size="100%">Stephen  Macko,</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Canuel, E. A.</style></author><author><style face="normal" font="default" size="100%">Harvey, J.W.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Tracking the fate of a high concentration groundwater nitrate plume through a fringing marsh: A combined groundwater tracer and in situ isotope enrichment study</style></title><secondary-title><style face="normal" font="default" size="100%">Limnology and Oceanography</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">&lt;Go to ISI&gt;://000172466500012</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">46</style></volume><pages><style face="normal" font="default" size="100%">1977-1989</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">A groundwater plume enriched in (NO3-)-N-15 was created upgradient of a mesohaline salt marsh. By measuring the changes in concentration and isotopic enrichment of NO3-, N2O, N-2, NH4+, and particulate organic nitrogen (PON) during plume transport through the marsh, in situ rates of dissimilatory nitrate reduction to ammonium (DNRA) and denitrification (DNF) were estimated, as well as N storage in the reduced N pools. For groundwater discharge within the top 10 cm of marsh, NO3- removal was 90% complete within the 50 cm of marsh nearest the upland border. The peak NO3- loss rate from the plume ranged from 208 to 645 muM d(-1). Rates of DNRA (180 muM d(-1)) and DNF (387-465 muM d(-1)) processed 30% and 70% of the NO3- load, respectively. Terminal N2O production was approximately equal to N-2 production rates during DNE Comparison of N-15 lost from the O-15(3)- pool and N-15 gained in each of the reduced products accounted for only 22% of the reduced N-15, thus indicating N export from the system. Despite high rates of DNRA, the NH+ produced was not a long-term repository for the groundwater-derived N but was instead rapidly immobilized into marsh PON and retained on longer timescales. The small inventory of N-15 in the N2O and N-2 pools relative to DNF rates, coincident with an undersaturation of dissolved argon, indicated that denitrified N was exported to the atmosphere on short timescales. The relative magnitudes of DNF and DNRA in conjunction with the immobilization of NH4+ and evasion of N gases dictated the extent of export versus retention of the groundwater NO3- load.</style></abstract><issue><style face="normal" font="default" size="100%">8</style></issue><accession-num><style face="normal" font="default" size="100%">LTER.2001-49278</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Neubauer, Scott C.</style></author><author><style face="normal" font="default" size="100%">Miller, W D.</style></author><author><style face="normal" font="default" size="100%">Anderson, I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Carbon cycling in a tidal freshwater marsh ecosystem: a carbon gas flux study</style></title><secondary-title><style face="normal" font="default" size="100%">Marine Ecology Progress Series</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2000</style></year></dates><volume><style face="normal" font="default" size="100%">199</style></volume><pages><style face="normal" font="default" size="100%">13-30</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><accession-num><style face="normal" font="default" size="100%">LTER.2000-49124</style></accession-num></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Anderson, I.</style></author><author><style face="normal" font="default" size="100%">Tobias, C.R.</style></author><author><style face="normal" font="default" size="100%">Neikirk, R.</style></author><author><style face="normal" font="default" size="100%">Wetzel, B. B.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Development of a Process-based Nitrogen Mass Balance Model for a Virginia Spartina alterniflora Salt Marsh: Implications for Net DIN Flux</style></title><secondary-title><style face="normal" font="default" size="100%">Marine Ecology Progress Series</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">VCR</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1997</style></year></dates><volume><style face="normal" font="default" size="100%">159</style></volume><pages><style face="normal" font="default" size="100%">13-27</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Primary production is nitrogen limited in most salt marshes with the possible exception of those impacted by high anthropogenic inputs of nitrogen. It is hypothesized that mature salt marshes which receive only small inputs of &quot;new&quot; nitrogen from the atmosphere, surface water runoff, groundwater, tidal creek, and nitrogen-fixation will have a conservative nitrogen cycle. We have developed a process-based N mass balance model for a short form Spartina alterniflora marsh in Virginia. Data for the model included rates of gross mineralization, nitrification, denitrification, nitrogen fixation, above- and below-ground macrophyte production, and benthic microalgal production. The annual balance between sources (mineralization, nitrogen fixation, tidal creek flux, atmospheric deposition, and sediment input) and sinks (above- and below-ground macrophyte uptake, sediment microalgal uptake, sediment burial, microbial immobilization, denitrification, and nitrification) of dissolved inorganic nitrogen (DIN) was determined for both interior S.  alterniflora -vegetated sites and unvegetated creek bank sites.  Sediment/water exchanges of DIN species, predicted by results of the mass balance analysis, were compared to measured exchanges. Annually sources and sinks of DIN in the vegetated marsh were in close balance.  The vegetated marsh imported DIN from the adjacent creek during most of the year; the unvegetated creek bank exported NH4+ to overlying tidal water during July and imported NH4+ during other seasons. The net flux of DIN was 5.7 gN m-2 y-1 from overlying water into the marsh; however, this flux was small relative to rates of internal N-cycling processes.  The sediment NH4+ pool turned over rapidly as a result of the high rate of gross mineralization (84 gN m-2 y-1). Other microbial N-cycling rates were low (0.6 - 4 gN m-2 y-1). The NH4+ supplied by mineralization was more than sufficient to support both macrophyte (33 gN m-2 y-1) and benthic microalgal (5 gN m-2 y-1) uptake. We propose that in order to maintain steady state in the system approximately half of the DIN mineralized is immobilized into a readily remineralizable particulate organic N pool. Since mineralization and macrophyte uptake are temporally out of phase the labile organic N pool may serve to temporarily sequester NH4+ until it is required for plant uptake.</style></abstract><accession-num><style face="normal" font="default" size="100%">LTER.1997-48870</style></accession-num></record></records></xml>