Marsh Water Research Articles

Experimental adsorption studies on different materials selected for developing a permeable reactive barrier for radiocesium retention

ABSTRACTCs-137 was accidentally spilled in an industrial waste repository located in a salt marsh in southern Spain, and a permeable reactive barrier was proposed to retain it. Cs adsorption properties of different natural clayey materials were analyzed. The salt marsh waters show high salinity and high chemical variability, therefore Cs adsorption was also analyzed in the presence of competitive ions, especially K+ and NH4+.Cs adsorption was non-linear in all the analyzed materials, indicating more than one adsorption sites with different selectivity. It was shown that in mixed clay systems with illite, montmorillonite and kaolinite, the presence of illite favors Cs retention at low and medium Cs loadings and montmorillonite at high Cs loadings. In the presence of illite and montmorillonite, kaolinite plays almost no role in Cs retention. The presence of K+ and NH4+ significantly hinders cesium adsorption.

Using in situ ultraviolet‐visual spectroscopy to measure nitrogen, carbon, phosphorus, and suspended solids concentrations at a high frequency in a brackish tidal marsh

The collection of high frequency water quality data are key to making the next leap in hydrological and biogeochemical sciences. Commercially available in situ ultraviolet‐visual (UV‐Vis) spectrometers make possible the long‐term collection of absorption spectra multiple times per hour. This technology has proven useful for measuring nitrate, dissolved organic carbon, and total suspended solids in many environments, but has not been tested in tidal marsh conditions where upstream freshwater mixes with estuarine waters, resulting in rapid changes in concentrations and salinity. These three parameters encompass only a portion of the nutrients that are of interest in these systems. To test the potential of spectroscopy to measure these and other nutrient concentrations, spectrometers were installed in a constructed brackish tidal marsh and absorbance spectra were compared to lab analyses for coinciding discrete samples. Variable selection techniques, including partial least squares regression, lasso regression, and stepwise regression, were used to develop models with which nitrate, total kjeldahl nitrogen, dissolved organic carbon, phosphate, total phosphorus, total suspended solids, and salinity in brackish marsh waters can be predicted from UV‐Vis spectrometer measurements. Significant relationships between the absorption spectra and the laboratory measured concentrations were observed for all of the parameters. Phosphate and total phosphorus were the only nutrients which had R2 values less than 0.86 for their best calibrations. This study shows the potential to collect multiple water quality parameters at a high frequency in brackish waters using in situ spectrometers and gives the tools to replicate this analysis in all environments.

Siderite ‘clumped’ isotope thermometry: A new paleoclimate proxy for humid continental environments

Clumped isotope measurements can be used to exploit the paleoclimatic potential of pedogenic siderite (FeCO3); however, the applicability of this method is held back by the lack of clumped isotope calibrations of mineralogies other than calcite and aragonite. Here we present an inorganic calibration of siderites grown in the laboratory between 21 and 51°C. Linear regression of Δ47 values and temperature (106/T2, K) yields the following relationship (r2=0.997):Δ47-RF=(0.0356±0.0018)×106T2+(0.172±0.019)We demonstrate that this calibration is indistinguishable from calcite at current levels of analytical precision. Our observations suggest that there is likely no large systematic bias in the clumped isotope acid fractionation factors between the two different carbonate minerals. We also present clumped isotope measurements of a natural siderite collected from Holocene sediments of the Mississippi River Delta. We find that siderites record warm season marsh water temperatures instead of mean annual temperatures as it has long been presumed. This finding has important implications for the accuracy of siderite stable isotope and clumped isotope based climate reconstructions.

Addressing the fouling of in situ ultraviolet-visual spectrometers used to continuously monitor water quality in brackish tidal marsh waters.

The introduction of portable in situ ultraviolet-visual spectrometers has made possible the collection of water quality parameters at a high frequency in dynamic systems such as tidal marshes. The usefulness of this technology is inhibited by fouling of the instrument's optics. In this study, a spectrometer fitted with manufacturer-recommended compressed air optical cleaning was installed in a brackish marsh to determine if fouling interfered with measurements between bi-weekly servicing. During a 2-wk period, the absorbance measured in air at 220 nm increased from 9 to 549 m, indicating major fouling. An antifouling system was developed that reduced the time of exposure of the optics to stream water and used a pressurized fresh water cleaning. After implementation of the system, the absorbance in air increased to at most 63 m after 2 wk of data collection. The dramatic reduction in fouling will allow quality long-term data to be collected using this technology.

Multi‐tissue stable isotope analysis and acoustic telemetry reveal seasonal variability in the trophic interactions of juvenile bull sharks in a coastal estuary

Understanding how natural and anthropogenic drivers affect extant food webs is critical to predicting the impacts of climate change and habitat alterations on ecosystem dynamics. In the Florida Everglades, seasonal reductions in freshwater flow and precipitation lead to annual migrations of aquatic taxa from marsh habitats to deep-water refugia in estuaries. The timing and intensity of freshwater reductions, however, will be modified by ongoing ecosystem restoration and predicted climate change. Understanding the importance of seasonally pulsed resources to predators is critical to predicting the impacts of management and climate change on their populations. As with many large predators, however, it is difficult to determine to what extent predators like bull sharks (Carcharhinus leucas) in the coastal Everglades make use of prey pulses currently. We used passive acoustic telemetry to determine whether shark movements responded to the pulse of marsh prey. To investigate the possibility that sharks fed on marsh prey, we modelled the predicted dynamics of stable isotope values in bull shark blood and plasma under different assumptions of temporal variability in shark diets and physiological dynamics of tissue turnover and isotopic discrimination. Bull sharks increased their use of upstream channels during the late dry season, and although our previous work shows long-term specialization in the diets of sharks, stable isotope values suggested that some individuals adjusted their diets to take advantage of prey entering the system from the marsh, and as such this may be an important resource for the nursery. Restoration efforts are predicted to increase hydroperiods and marsh water levels, likely shifting the timing, duration and intensity of prey pulses, which could have negative consequences for the bull shark population and/or induce shifts in behaviour. Understanding the factors influencing the propensity to specialize or adopt more flexible trophic interactions will be an important step in fully understanding the ecological role of predators and how ecological roles may vary with environmental and anthropogenic changes.

Evaluation of DNA Damage in Eurasian Marsh Frogs (Pelophylax ridibundus) by Comet Assay for Determination of Possible Pollution in the Different Lakes in Central Anatolia, Turkey

In the present study, adult Eurasian marsh frogs, Pelophylax ridibundus, and water samples were collected from a reference lake and three water bodies in central Anatolia, Turkey, to evaluate the water for chemical pollutants and possible effects of pollutants on the DNA of frog erythrocytes by using a comet assay. The results for DNA damage parameters of the comet assay (total comet length, tail intensity, and olive tail moment) and their statistical analysis by ANOVA demonstrated that P. ridibundus and the comet assay together represent an useful approach for the early detection of polluted water bodies.

Tree Island Response to Fire and Flooding in the Short-Hydroperiod Marl Prairie Grasslands of the Florida Everglades, USA

Within the marl prairie grasslands of the Florida Everglades, USA, the combined effects of fire and flooding usually lead to very significant changes in tree island structure and composition. Depending on fire severity and post-fire hydroperiod, these effects vary spatially and temporally throughout the landscape, creating a patchy post-fire mosaic of tree islands with different successional states. Through the use of the Normalized Difference Vegetation Index (NDVI) and three predictor variables (marsh water table elevation at the time of fire, post-fire hydroperiod, and tree island size), along with logistic regression analysis, we examined the probability of tree island burning and recovering following the Mustang Corner Fire (May to June 2008) in Everglades National Park. Our data show that hydrologic conditions during and after fire, which are under varying degrees of management control, can lead to tree island contraction or loss. More specifically, the elevation of the marsh water table at the time of the fire appears to be the most important parameter determining the severity of fire in marl prairie tree islands. Furthermore, in the post-fire recovery phase, both tree island size and hydroperiod during the first year after the fire played important roles in determining the probability of tree island recovery, contraction, or loss.

Interaction between continental and estuarine waters in the wetlands of the northern coastal plain of Samborombón Bay, Argentina

On the Samborombón Bay coastline, located in the Río de la Plata estuary in Buenos Aires province (Argentina), a complex hydrological system has developed at the interface between continental and estuarine water, where significant wetlands develop. The main hydrogeological units, namely the shell ridges, the tidal plain and the marsh areas, have been identified using geomorphological criteria. Water table, hydrochemical and isotopic data have been used to determine their hydrological features, as well as those of the streams and canals. Evaporation processes, in particular, have been considered when depicting chemical and isotopic changes in surface waters in streams and marsh areas. The shell ridges represent a hydrogeological unit in which rainwater is stored, constituting a lens-shaped freshwater aquifer. In this unit, just as in the tidal plain, carbonate dissolution and ion exchange are the main processes regulating water chemistry. On the other hand, in the marsh and surface waters, processes such as mixing with estuarine water and evaporation predominate. These processes control water fluxes and the salinity of the wetland areas and, consequently, their ability to preserve the existing biodiversity. This study shows the importance of knowledge of hydrochemical processes in any proposal concerning the management and preservation of this type of wetland.

Suppression of cyanobacterial growth of Aphanizomenon flos-aquae by vascular plant decomposition products in Upper Klamath Lake, Oregon

Upper Klamath Lake in southwestern Oregon has experienced harmful algal blooms of the nitrogen-fixing cyanobaterium Aphanizomenon flos-aquae for 5 decades. The appearance of A. flos-aquae coincided with loss of wetlands to agricultural use starting at the end of the 19th century. Plant degradation produces colored dissolved organic matter (CDOM) or humic substances that affect algal and cyanobacterial growth. We conducted a series of controlled laboratory assays and an in situ limnocorral experiment to assess the effectiveness of plant materials that contribute high levels of CDOM upon decomposition (i.e., barley straw, barley straw extracts, marsh water, and wetland plants) to suppress growth of the cyanobacterium A. flos-aquae. Our results indicate that the application of barley straw or dried wetland plants were most effective at suppressing growth or causing mortality of A. flos-aquae. Mortality was dependent on the amount of CDOM released and incident ultraviolet (UV) light. We hypothesize that mortality is due to the well-known production of reactive oxygen species from the absorption of UV light by CDOM. In general, direct application of plant material under high UV exposure resulted in near complete A. flos-aquae mortality within 24 hours. Because the mortality was rapid, these results are consistent with toxicosis and not the binding of essential nutrients. We suggest that fringing wetlands may play an important role in regulating harmful cyanobacterial blooms by providing CDOM and that this role should be considered when determining wetland value.

Fluxes of water, sediments, and biogeochemical compounds in salt marshes

Tidal oscillations systematically flood salt marshes, transporting water, sediments, organic matter, and biogeochemical elements such as silica. Here we present a review of recent studies on these fluxes and their effects on both ecosystem functioning and morphological evolution of salt marshes. We reexamine a simplified model for the computation of water fluxes in salt marshes that captures the asymmetry in discharge between flood and ebb. We discuss the role of storm conditions on sediment fluxes both in tidal channels and on the marsh platform. We present recent methods and field instruments for the measurement of fluxes of organic matter. These methods will provide long-term data sets with fine temporal resolution that will help scientists to close the carbon budget in salt marshes. Finally, the main processes controlling fluxes of biogenic and dissolved silica in salt marshes are explained, with particular emphasis on the uptake by marsh macrophytes and diatoms.

Implications of multi-scale sea level and climate variability for coastal resources

While secular changes in regional sea levels and their implications for coastal zone management have been studied extensively, less attention is being paid to natural fluctuations in sea levels, whose interaction with a higher mean level could have significant impacts on low-lying areas, such as wetlands. Here, the long record of sea level at Key West, FL is studied in terms of both the secular trend and the multi-scale sea level variations. This analysis is then used to explore implications for the Everglades National Park (ENP), which is recognized internationally for its ecological significance, and is the site of the largest wetland restoration project in the world. Very shallow topographic gradients (3–6 cm per km) make the region susceptible to small changes in sea level. Observations of surface water levels from a monitoring network within ENP exhibit both the long-term trends and the interannual-to-(multi)decadal variability that are observed in the Key West record. Water levels recorded at four long-term monitoring stations within ENP exhibit increasing trends approximately equal to or larger than the long-term trend at Key West. Time- and frequency-domain analyses highlight the potential influence of climate mechanisms, such as the El Nino/Southern Oscillation and the North Atlantic Oscillation (NAO), on Key West sea levels and marsh water levels, and the potential modulation of their influence by the background state of the North Atlantic Sea Surface Temperatures. In particular, the Key West sea levels are found to be positively correlated with the NAO index, while the two series exhibit high spectral power during the transition to a cold Atlantic Multidecadal Oscillation (AMO). The correlation between the Key West sea levels and the NINO3 Index reverses its sign in coincidence with a reversal of the AMO phase. Water levels in ENP are also influenced by precipitation and freshwater releases from the northern boundary of the Park. The analysis of both climate variability and climate change in such wetlands is needed to inform management practices in coastal wetland zones around the world.

Sustainability of a Tidal Freshwater Marsh Exposed to a Long-term Hydrologic Barrier and Sea Level Rise

A 115-year-old railroad levee bisecting a tidal fresh- water marsh perpendicular to the Patuxent River (Maryland) channel has created a northern, upstream marsh and a southern, downstream marsh. The main purpose of this study was to determine how this levee may affect the ability of the marsh system to gain elevation and to determine the levee's impact on the marsh's long-term sustainability to local relative sea level rise (RSLR). Previously unpublished data from 1989 to 1992 showed that suspended solids and short-term sediment deposi- tion were greater in the south marsh compared to the north marsh; wetland surface elevation change data (1999 to 2009) showed significantly higher elevation gain in the south marsh compared to the north (6±2 vs. 0±2 mm year −1 , respectively). However, marsh surface accretion (2007 to 2009) showed no significant differences between north and south marshes (23± 8 and 26±7 mm year −1 , respectively), and showed that shallow subsidence wasan important process in both marshes. A strong seasonal effect was evident for both accretion and elevation change, with significant gains during the growing season and elevation loss during the non-growing season. Sediment trans- port, deposition and accretion decreased along the intertidal gradient, although no clear patterns in elevation change were recorded. Given the range in local RSLR rates in the Chesa- peake Bay (2.9 to 5.8 mm year −1 ), only the south marsh is keeping pace with sea level at the present time. Although one would expect the north marsh to benefit from high accretion of abundant riverine sediments, these results suggest that long- term elevation gain is a more nuanced process involving more than riverine sediments. Overall, other factors such as infrequent episodic coastal events may be important in allowing the south marsh to keep pace with sea level rise. Finally, caution should be exercised when using data sets spanning only a couple of years to estimate wet- land sustainability as they may not be representative of long- term cumulative effects. Two years of data do not seem to be enough to establish long-term elevation change rates at Jug Bay, but instead a decadal time frame is more appropriate.

Development of a Reproducible Method for Determining Quantity of Water and its Configuration in a Marsh Landscape

ABSTRACT Suir, G.M.; Evers, D.E.; Steyer, G.D., and Sasser C.E., 2013. Development of a reproducible method for determning quantity of water and its configuration in a marsh landscape. In: Brock, J.C.; Barras, J.A., and Williams, S.J. (eds.), Understanding and Predicting Change in the Coastal Ecosystems of the Northern Gulf of Mexico, Journal of Coastal Research, Special Issue No. 63, pp. 110–117, Coconut Creek (Florida), ISSN 0749-0208. Coastal Louisiana is a dynamic and ever-changing landscape. From 1956 to 2010, over 3,734 km2 of Louisiana's coastal wetlands have been lost due to a combination of natural and human-induced activities. The resulting landscape constitutes a mosaic of conditions from highly deteriorated to relatively stable with intact landmasses. Understanding how and why coastal landscapes change over time is critical to restoration and rehabilitation efforts. Historically, changes in marsh pattern (i.e., size and spatial distribution of marsh landmasses and water bodies) have been disti...

Greenhouse Experimental Methods Towards in-situ Burial and Restoration of Contaminated Sites in Submerged Wetlands

As a result of commercial and industrial activit ies conducted in the absence of environmental regulations and enforcement in the past, sediments contaminated by organic compounds, heavy metals, and other potentially to xic chemicals have accu mulated in many of the world's deepwater and wet land environ ments. These sediment-borne contaminants can eventually become incorporated into aquatic food webs and adversely affect ecological receptors like benthic organisms and fish, and u ltimately pose a risk to hu man health. This laboratory research tested a commercial product AquaBlok TM (patented, composite-aggregate technology comprised of a solid core, an outer layer of clay material, and polymers) as an in-situ capping technology that could be used to remediate and/or manage contaminated sediments in the New Jersey Hackensack Meadowlands, a superfund site. In a greenhouse setting, tubs containing representative Meadowland marsh soil and water were capped with AquaBlok. This research not only examined the potential use of this product as an in-situ capping material and possible substrate for flora co lonization, but also examined the imp rovements of the same patented, clay mineral-based composite aggregate technology (SubmerSeed TM ) as an alternative to tradit ional means of wetland p lant propagation. At the end of a two-year period, both the sediment/cap and vegetation plant tissues were examined for metallic contaminants (including Cd, Cr, Cu, Pb, Hg, and Zn). Overall, capping provided a less contaminated substrate. Results indicated that AquaBlok cap alone did not allow contaminants in the sediment belo w to breakthrough. Nevertheless, vegetation colonization was restricted to a limited number of plant species. Furthermore, plants growing in AquaBlok were less robust with lower dry weight and s maller root system than plants growing in uncapped sediments despite the fact that their tissue contained smaller amounts of metallic contaminants. The improvements of the clay mineral-based composite aggregate technology (Sub merSeeds) as an alternative to trad itional means of plant propagation worked very well in successfully delivering aquatic plant seeds into permanently inundated conditions.

Brief Summary of Jetty Island History

More than 50,000 people annually come to a two-mile long, man-made island in Everett, Washington to relax on sandy beaches, wade in warm and shallow water, join guided nature hikes, watch wildlife, kayak around the perimeter and kite board with steady afternoon winds. Jetty Island is recognized today as one of Snohomish County’s top recreational and wildlife resources but if the founders of Everett had achieved their goals then the riprap jetty would have more closely resembled Seattle’s Harbor Island. Today’s Jetty Island is not only a top tourist destination but also a wildlife conservation area. Its sandy beaches, mud flat and salt water marshes provide important habitat not as readily available elsewhere in Snohomish River delta. It supports an abundance of wildlife, including bald eagles, Chinook salmon, osprey, bull trout, and blue heron. In fact, observers have identified 115 species of birds in the vicinity of the island. Everett’s treasured island may not have realized the potential envisioned by city founders but it stands in sharp contrast to Seattle’s Harbor Island, an industrialized and toxic Superfund site.

Quantifying groundwater discharge from different sources into a Mediterranean wetland by using 222Rn and Ra isotopes

► 222 Rn and Ra proved to be a suitable tracer of groundwater discharge to coastal wetlands. ► 222 Rn, 226 Ra and salinity allowed estimating the contribution of different groundwater sources. ► Ra isotopes allowed estimating the wetland water age. ► Monthly groundwater inflows from two aquifers were successfully monitored. Groundwater discharge constitutes the main water inflow of many coastal wetlands. Despite the potential of Ra isotopes and 222 Rn as tracers of groundwater discharge, the use of these radionuclides to quantify the groundwater inflow in coastal wetlands has been only scarcely addressed in the literature. The main goal of this study is to evaluate the use of 222 Rn and Ra isotopes to estimate the contribution of distinct groundwater sources into a Mediterranean coastal wetland (the Peníscola marsh, Castelló, Spain). The Peníscola marsh is a small shallow wetland nourished by groundwater coming from four different flowpaths: (i) a deep flow from the regional carbonate aquifer of El Maestrat, (ii) a shallow flow and (iii) an intermediate flow, both from the Irta Range and the detritic Vinaròs-Peníscola aquifer, and (iv) seawater intrusion. Data on 226 Ra, 222 Rn and salinity obtained in summer 2007 revealed that the deep groundwater contribution was 15% of the total water inflow, whereas the shallow and intermediate flow paths represented 32% and 48%, respectively. Seawater accounted only for the remaining 5% inputs to the wetland. Ra isotopes also allowed estimating the marsh water age in 1.2 days. Both the groundwater contributions derived from 222 Rn measurements and the Ra-derived marsh water age agreed well with the direct measurements obtained using propeller flow meters, evidencing the effectiveness of the used methods. An interannual comparison between the estimated groundwater inflow and the precipitation revealed that shallow groundwater flows respond to local precipitation, whereas the deep groundwater flow from the carbonate aquifer is dominated by a constant baseflow.

Herbiciding invasive reed: indirect effects on habitat conditions and snail–algal assemblages one year post-application

Invasive common reed (Phragmites australis) can rapidly form expansive, near-monotypic stands, and thereby lower plant diversity and change marsh habitat structure. Consequently, North American wetland managers often use herbicides, such as glyphosate-based AquaNeat® and imazypr-based Habitat®, to control its establishment and spread. However, herbiciding might indirectly affect benthic community structure by directly altering habitat structure, and habitat alterations may vary with herbicide and concentration. These effects may be particularly pronounced ≥1 year post-herbiciding when dead above-ground biomass collapses and submerges. To evaluate how herbicide-caused alterations in habitat affect key trophic linkages, we compared snail and epiphytic algal assemblages, and habitat conditions, among 20- × 20-m replicated plots of reed treated with either AquaNeat® (30 % solution), Habitat® (5 % solution), or left herbicide-free (i.e., controls) in an eutrophic Lake Erie coastal marsh 1-y post-herbiciding. Both herbicides equally reduced reed above-ground growth by >90 % relative to controls. Fossaria spp. and Gyraulus parvus snails were more abundant in herbicide-treated plots than in controls, but Shannon-Wiener diversity was similar (H′ ≈ 1.0) across treatments. All snails collected were pulmonates, suggesting habitat drying might be driving assemblage structure. Snails were denser in plots with metaphyton (mostly Spirogyra) than without, and metaphyton was more abundant in herbicide-treated plots with higher incident light levels and warmer water temperatures than in controls. Snail biomass was positively related to amount of benthic macro-organic matter but not epiphytic algal biomass, which was similar among treatments. Diatoms dominated algal communities in all treatments. In June, Navicula spp. was dominant in controls, whereas Nitzschia palea and Aulacoseira italic, and Nitzschia spp., were dominant in AquaNeat® and Habitat® treatments, respectively. However, algal and diatom assemblages were similar in treatments by early-July when marsh water levels significantly decreased and nitrate levels were <1 μg/L. Marsh hydrologic patterns may mediate herbiciding’s indirect effects on trophic structure.

Deterioration of bioplastic carrier bags in the environment and assessment of a new recycling alternative

Increasing environmental concerns and the introduction of technologies based on renewable resources have stimulated the replacement of persistent petroleum-derived plastics with biodegradable plastics from biopolymers. As a consequence, a variety of products are currently manufactured from bioplastic, including carrier bags. This series of studies investigated the deterioration of carrier bags made with Mater-Bi (MB), a starch-based bioplastic, in soil, compost and two aquatic ecosystems, a littoral marsh and seawater. Results from the laboratory study indicated that bioplastic carrier bags were rapidly deteriorated in soil and compost. After three months of incubation, weight loss of specimens was of 37% and 43% in soil and compost, respectively. Conversely, little deterioration was observed in specimens buried in soil under field conditions or exposed to water of a littoral marsh and of the Adriatic Sea. These findings were consistent with the greater number of bacteria and especially fungi capable of degrading MB that were recovered from soil and compost with respect to the two aquatic ecosystems. Considering that a variety of microbial isolates are capable of using MB as a source of carbon, a new alternative to recycle these MB-based carrier bags was explored. More specifically, starchy residues from bags were fermented by the fungus Rhizopus oryzae to produce up to 35mg of lactic acid per g of bag residues.

Marsh construction techniques influence net plant carbon capture by emergent and submerged vegetation in a brackish marsh in the northwestern Gulf of Mexico

Coastal marshes play an important role in global carbon cycles, yet coastal development has led to widespread losses of marsh habitat. To address this problem, many coastal wetlands have been restored or created over the past several decades using a variety of construction techniques, but it is unclear if net plant carbon capture in constructed marshes is equal to that of reference marshes, or if rates of plant carbon capture are influenced by marsh construction techniques. To comparatively assess relative carbon capture by emergent and submerged vegetation in constructed and reference marshes, we measured standing biomass and carbon content in above- and belowground emergent plant tissue and submerged vegetation in three constructed areas (2–3 years old) and one reference area in a brackish marsh in the northwestern Gulf of Mexico in 2009 and 2010. We also used aerial photographs to construct a GIS database of emergent and submerged vegetation coverage. These data were combined to estimate net annual plant carbon capture per square meter of marsh vegetation in each constructed and reference area. This index of carbon input to wetland vegetation suggests that rates of carbon capture by emergent aboveground vegetation and submerged aquatic vegetation were similar in constructed and reference areas. However, submerged vegetation captured less carbon (0.1–0.3kgm−2) than emergent vegetation (0.2–1.7kgm−2), and constructed areas contained an order of magnitude less emergent habitat than the reference area. Consequently, the annual carbon production of entire constructed areas (emergent+submerged vegetation; 0.1–1.2kgm−2) was always less than half that of the reference area (0.8–2.5kgm−2). Therefore, although productivity of emergent and submerged vegetation in constructed and reference areas was similar, the smaller ratio of land to water in the constructed areas reduced their annual rate of plant carbon capture at a larger spatial scale. To more closely mimic rates of plant carbon capture in reference marsh habitats, constructed marsh designs should aim to replicate the ratio of land to water in adjacent reference marshes.

Integrated Marsh Management (IMM): a new perspective on mosquito control and best management practices for salt marsh restoration

Salt marsh management often embraces diverse goals, ranging from the restoration of degraded marshes through re-introduction of tidal flow to the control of salt marsh mosquito production by altering marsh surface topography through Open Water Marsh Management (OMWM). However, rarely have these goals been incorporated in one project. Here we present the concept of Integrated Marsh Management (IMM), which combines the best management practices of salt marsh restoration and OMWM. Although IMM offers a comprehensive approach to ecological restoration and mosquito control, research evaluating this concept’s practical implementations has been inadequate. A long-term IMM project at Wertheim National Wildlife Refuge located in a highly urbanized watershed on Long Island, New York, USA was designed to fill this knowledge gap. A combination of restoration and OMWM techniques was employed at two treatment marshes, the results monitored before and after alterations, and compared to two adjacent control marshes. The treatment marshes experienced decreased mosquito production, reduced cover of the invasive common reed (Phragmites australis), expansion of native marsh vegetation, increased killifish and estuarine nekton species abundance, as well as increased avian species diversity and waterbird abundance. This demonstration project validated the IMM conceptual approach and may serve as a case study for similar IMM projects in the future.