Despite the recognized importance of wetlands as habitat for fishes and the growing need to assess and manage human impacts on that habitat, there is little information on patterns and variability of habitat within Great Lakes coastal wetlands. Our goal was to describe wetland aquatic habitat patterns and the natural factors that organize them as a step towards developing habitat assessment schemes and identifying experimental design elements for future synoptic surveys. We analyzed data on aquatic vegetation structure, water chemistry, and water movement (inferred from gypsum plug dissolution) in relation to hydrology and morphology in inundated segments of ten relatively un-impacted coastal marshes of western Lake Superior. Spatial differences in aquatic habitat within wetlands were as large or larger than differences among wetlands, and habitat patterns were strongly associated with morphology and hydrology. Back-bay segments tended to have greater vegetation cover and structural complexity and lower levels of water movement, and they were prone to high water temperatures and low dissolved oxygen levels in wetlands having little seiche activity. Increasing seiche inputs tended to homogenize habitat elements among wetland segments, while increasing tributary inputs tended to increase spatial variability. Patterns in emergent vegetation differed from patterns in submerged/floating vegetation, and different assessment metrics may be needed for different plant zones. Segment-scale sampling schemes like those used in this study have the potential to elucidate habitat patterns within inundated portions of wetlands with a reasonable level of effort. Human impacts on coastal wetland fish habitat must be interpreted in the context of natural spatial heterogeneity as structured by wetland morphology and magnitude of seiche and tributary inputs.

The purpose of this experiment was to investigate the survival and biomass accumulation of wetland plant species under different water depths in controlled microcosms. In the greenhouse, two-week-old seedlings were randomly assigned to one of seven water-depth treatments (−6, −4, −2, 0, 2, 4, and 6 cm relative to the soil surface) and allowed to grow for six months. Species included five perennial sedges, four perennial and one annual grasses, and two perennial and two annual forbs. Twelve of the species had their lowest biomass and lowest survivorship at water depths greater than 0 cm. The root:shoot ratio, however, did not change across water-depth treatments. Biomass accumulation differed by plant form (sedges>forbs>grasses). Annuals had the greatest biomass values across the widest range of water depths compared to perennials. Of the fourteen plants tested, Lythrum salicaria (purple loosestrife), one of the two invasive, non-native species tested, had the greatest biomass at water depths from −6 to 2, whereas Phalaris arundinacea (reed canarygrass), the other invasive, had comparatively small mean biomass values. Ranking of biomass between species was highly concordant between non-flooded treatments but not significantly concordant between flooded treatments indicating that plant species have distinct responses to flooding. This research suggests that newly established plant seedlings in wetland restorations should not be submerged, or if submergence is unavoidable, annuals and sedges may be more tolerant of prolonged flooding.

This study analyzes the phytoplankton structure and dynamics, as well as the main limnological characteristics in Los Coipos Lake, located in the Reserva Ecológica Costanera Sur (Buenos Aires, Argentina). Phytoplankton generic composition was studied before (April–June 1998), during (July 1998–December 1999), and after (January–October 2003) pumping from the Puelche aquifer waters, characterized by extremely high conductivity values. The capacity of natural recovery from salt contamination was analyzed. The 1998–1999 parameters were obtained from a technical database (Aguas Argentinas water supply company), while two-monthly samples were collected and analyzed between January and October 2003. Decrease and replacement of genera was related to the conductivity increase; recovery of the number of genera was recorded once the input ceased. Chlorophyceae and Cyanophyceae were responsible for the greatest phytoplankton densities. During ground-water input, four high phytoplankton density events were recorded. One hundred fifty-three infrageneric phytoplanktonic and tichoplanktonic taxa were registered during 2003, together with high total phytoplankton densities. Phytoplankton structure and dynamics did not seem to be regulated by dissolved salt content in the post-pumping period.

Bat activity in the southeastern United States is concentrated over riparian areas and wetland habitats. The restoration and creation of wetlands for mitigation purposes is becoming common in the Southeast. Understanding the effects of these restoration efforts on wetland flora and fauna is thus becoming increasingly important. Because bats (Order: Chiroptera) consist of many species that are of conservation concern and are commonly associated with wetland and riparian habitats in the Southeast (making them a good general indicator for the condition of wetland habitats), we monitored bat activity over restored and reference Carolina bays surrounded by pine savanna (Pinus spp.) or mixed pine-hardwood habitat types at the Savannah River Site in South Carolina. In order to determine how wetland restoration efforts affected the bat community, we monitored bat activity above drained Carolina bays pre- and post-restoration. Our results indicate that bat activity was greater over reference (i.e., undrained) than drained bays prior to the restorative efforts. One year following combined hydrologic and vegetation treatment, however, bat activity was generally greater over restored than reference bays. Bat activity was also greater over both reference and restored bays than in random, forested interior locations. We found significantly more bat activity after restoration than prior to restoration for all but one species in the treatment bays, suggesting that Carolina bay restoration can have almost immediate positive impacts on bat activity.

We present an analysis of modern pollen and diatom assemblages in surficial sediments in a coastal marsh at Rondeau Provincial Park, on the northern shore of Lake Erie in southwestern Ontario, Canada. The objectives of the study were (1) to determine how pollen and diatom assemblages in surface sediments vary as a function of the dominant vegetation community and moisture availability at the sampling site and (2) to analyze pollen-vegetation relationships of four dominant wetland plants: Cephalanthus occidentalis, Phragmites australis, Typha spp., and Zizania aquatica, in order to improve interpretations of fossil sequences. Canonical variate analysis (CVA) was used to compare pollen and diatom spectra from sampling sites in three marsh zones delineated on the basis of moisture availability. Using the pollen or the diatom datasets, the resulting discriminant functions correctly classified 86% of the wettest sites, 72% of those with intermediate moisture availability, and only 25% of the sites in the driest parts of the wetland. Since 35% of the sampling sites were misclassified by the CVA on the basis of pollen assemblages, a representation factor approach is needed to complement the comparative approach when analyzing pollen datasets from wetland contexts. Percent cover vegetation data at sediment sampling sites are used to illustrate pollen-vegetation relationships for the ecologically important wetland plants at the site. Phragmites australis and Typha spp. produce small amounts of pollen relative to their abundance, while Cephalanthus occidentalis and Zizania aquatica produce abundant pollen, which is deposited highly locally in the case of Cephalanthus. These data will enable improved interpretations of fossil pollen and diatom sequences from wetland contexts.

We undertook a survey of the vegetational ecology of 94 peatlands at Duck Mountain, Manitoba to discriminate differences among peatland types at the southeastern edge of the boreal plain, especially black spruce swamps, and to clarify boreal swamp terminology. The majority of peatlands surveyed were wooded, relatively small (mean = 1.8 ha), and in depressions on the landscape. A classification and indicator species analysis identified the dominant peatland types as moderate-rich fens, with bogs and extreme-rich fens as rare. Black spruce swamps were relatively common and often found on gentle slopes. They were distinguished from wooded fens by larger trees (mean height = 9.7 m; diameter = 12.6 cm), denser overstory (68%), shallower peat depth (90 cm), and small size (1.6 ha). Although most similar to wooded moderate-rich fens by vegetation, black spruce swamps have a denser bryophyte layer and more mesic plant species. Significant indicator species on hummocks and drier areas include Pleurozium schreberi, Hylocomium splendens, Equisetum sylvaticum, Petasites frigidus var. palmatus, Cornus canadensis, Linnaea borealis, Rosa acicularis, Moneses uniflora, Geocaulon lividum, Orthillia secunda, Equisetum arvense, Listera cordata, and Mertensia paniculata. Species characteristically found in black spruce swamp hollows include Rhizomnium pseudopunctatum, Rhizomnium gracile, and Plagiochila porelloides. We discuss conifer swamp terminology globally, and recommend that black spruce swamps be recognized as a peatland type distinct from eastern white cedar-dominated boreal swamps found in the eastern boreal region, wooded fens, and black spruce-dominated uplands. The environmental gradients most strongly associated with an ordination of the Duck Mountain peatland plant community data were forest mensuration variables, e.g., overstory density (range = 7–80%), peat depth (0.4– 3.0 m), peat C:N (14–67), organic C (54–98%), bulk density (0.19–64.00 g/cc), surface-water temperature (3.0–19.5 °C), specific conductivity (0–989 μS/cm), and Ca² (1.8–111.4 mg/L). Wooded bogs were distinguished from the other peatland types based on mean pH (3.8), alkalinity (0.2 mg/L), Ca² (5.0 mg/L) and other cations, but there was much overlap among the fens and black spruce swamp. A number of isolated, topographically high, open peatlands were characterized by plant species with affinities to open moderate-rich fens, including Drepanocladus aduncus, Helodium blandowii, Salix discolor, Equisetum fluviatile, and Calamagrostis canadensis, but mean surface water pH (5.4), Ca² (13 mg/L), DOC (47 mg/L), and NH₄ (188 μg/L) were more similar to wooded bogs. This may be the consequence of fluctuating water levels. The potential impact of climate change, in addition to current impacts from logging, emphasizes the importance of understanding the vegetation and environmental variables in southern boreal peatlands.

Unregulated river floodplains are dynamic environments, and invertebrates living in these wetlands must be able to respond to fluctuating water levels. As water levels decrease in the floodplain, aquatic and semi-aquatic invertebrates may either move with the receding water or remain and become exposed to drying on non-inundated floodplain soil. Invertebrates inhabiting floodplains may use several strategies to cope with exposed (non-inundated) conditions; they may survive exposure by forming desiccation-resistant stages, emerging as adults (insects only), or living in a non-dormant state in exposed soil. To investigate invertebrate responses to a receding water line, benthic core samples were collected in exposed and inundated floodplain soil at successively lower water levels after a flood in the Sipsey River floodplain, west central Alabama. Insect emergence was also compared on inundated and exposed floodplain. Some invertebrate groups moved with the receding water line (aquatic chironomids, ostracods, cladocerans, copepods, Acari, and stratiomyids), while others did not (semi-aquatic/terrestrial chironomids, collembolans, oligochaetes, nematodes, diplurans, proturans, tenebrionids, and sciarids). Chironomids were the dominant emerging insect (73%), and adults emerged from both inundated (33 individuals m⁻² d⁻¹) and exposed floodplain soil (15 individuals m⁻² d⁻¹). These results document the importance of at least two survival strategies for aquatic invertebrates: moving with decreasing water levels and emerging from exposed floodplain soil (insects only). The semi-aquatic taxa not responding to receding water can survive in both exposed and inundated soil, at least for the short period observed in this study. Thus, many floodplain invertebrates in small-to-medium sized rivers are able to cope with a dynamic and unpredictable inundation pattern, which likely enhances wetland productivity.

Forms, amounts, and accumulation of soil phosphorus (P) were measured in natural and recently restored marshes surrounding Upper Klamath Lake located in south-central Oregon, USA to determine rates of P accumulation in natural marshes and to assess changes in P pools caused by long-term drainage in recently restored marshes. Soil cores were collected from three natural marshes and radiometrically dated to determine recent (¹³⁷Cs-based) and long-term (²¹⁰Pb-based) rates of peat accretion and P accumulation. A second set of soil cores collected from the three natural marshes and from three recently restored marshes was analyzed using a modification of the Hedley procedure to determine the forms and amounts of soil P. Total P in the recently restored marshes (222 to 311 μg cm⁻³) was 2–3 times greater than in the natural marshes (103 to 117 μg cm⁻³), primarily due to greater bulk density caused by soil subsidence, a consequence of long-term marsh drainage. Occluded Fe- and Al-bound P_i, calcium-bound P_i and residual P were 4 times, 22 times, and 5 times greater, respectively, in the recently restored marshes. More than 67% of the P pool in both the natural and recently restored marshes was present in recalcitrant forms (humic-acid P_o and residual P) that provide long-term P storage in peat. Phosphorus accumulation in the natural marshes averaged 0.45 g m⁻² yr⁻¹ (¹³⁷Cs) and 0.40 g m⁻² yr⁻¹ (²¹⁰Pb), providing a benchmark for optimizing P sequestration in the recently restored marshes. Effective P sequestration in the recently restored marshes, however, will depend on re-establishing equilibrium between the P-enriched soils and the P concentration of floodwaters and a hydrologic regime similar to the natural marshes.

The Floristic Quality Index (FQI) is a tool used to assess the conservation value of natural areas and monitor restoration success. Each native plant species is assigned a coefficient of conservatism, a subjective rating that describes its affinity for remnant natural areas. To calculate FQI, mean coefficient of conservatism (mean C) at a site is multiplied by the square root of native species richness. However, use of FQI is sometimes problematic, mainly because it incorporates species richness, which often varies with factors other than site conservation value. We surveyed 231 wetlands in a contiguous landscape that included the Beaucoup Creek floodplain in southern Illinois, USA and investigated the influence of landscape and site characteristics on species richness, mean C, FQI, and the proportion of site floras made up by wetland species and exotic species. Species richness and FQI increased significantly with site area or perimeter, indicating a bias toward higher assessments of quality in larger areas. Species richness and FQI in emergent wetlands increased with sampling date, suggesting that these sites should only be surveyed late in the growing season. Mean C and the proportion of site flora made up by wetland species decreased with increasing inter-wetland distance, indicating that isolation affects species composition. Both decreasing area and increasing inter-wetland distance were associated with lower FQI scores. Mean C, although not completely area-independent, was less strongly correlated with sampling date or area and may provide a more robust indicator of relative site conservation value than FQI when using the metrics to evaluate conservation value of jurisdictionally delineated plant communities.

Temperature effects on soil microbiological activity were well-documented in the first half of the 20^th century, and many workers recognized that most (mesophyllic) soil microbes became relatively inactive at temperatures below 5° to 10° C. The term biologic zero first was published in the soil science literature in the first edition of Soil Taxonomy, where it was described as the temperature (5° C) below which biological activity is sufficiently low that reducing conditions do not readily develop in saturated soils. While acknowledged as a generalization and simplification, this microbiologically based concept has continued to be affirmed by numerous workers in soil and wetland science. In the last two decades, the term has worked its way into numerous regulatory documents, usually associated with the concept or definition of growing season. Most recently, a new definition of biologic zero has been introduced by the National Technical Committee for Hydric Soils (NTCHS), which no longer is related primarily to soil microorganisms but, rather, is tied to higher plants. The new definition binds biologic zero to measurements taken at a specified depth (50 cm) and appears to be driven by an interest to modify and define better the concept of growing season for cooler climates. This change represents a fundamental departure from the long-held concept of biologic zero and may have significant ramifications on wetland regulatory issues.

In the Okavango Delta in Botswana, dissolved organic matter (DOM) transport is controlled by the slow movement of an annual flood ‘pulse’ across permanently and seasonally flooded wetlands, known respectively as the Permanent Swamp and Seasonal Swamp. We studied temporal and spatial variations in fluorescence index (FI) and specific UV absorbance (SUVA) of DOM to identify DOM sources and fate during the flood. Dissolved organic carbon (DOC) concentrations ranged from 2 to 25 mg C L⁻¹ in channels of the Delta, with seasonal floodplains having consistently higher concentrations. Chemical indices, such as DOC concentrations, conductivity, specific UV absorbance (SUVA), fluorescence, total dissolved nitrogen, and chlorophyll a, were analyzed for channel and floodplain sites in the Seasonal Swamp. DOC concentrations increased during the rising limb of the flood in the Seasonal Swamp. SUVA of whole water samples and fluorescence index (FI) of fulvic acids isolated from channel and floodplain sites changed in a manner indicating the release of DOM by leaching of plant litter during the flood. After the flood receded, DOC concentrations and fulvic acid content decreased, and microbially-derived sources of organic matter dominated. Along two river reaches, measuring over 400 km each, variations in DOC concentrations were primarily due to geomorphology, with the effects of the annual flood overprinted atop the spatial controls. Increasing downstream DOC concentrations were found to be a product of inundation of DOC-rich seasonal floodplains and evaporation-enriched waters downstream. Increasing SUVA, dissolved nitrogen, and fulvic acid content, and decreasing FI downstream suggested microbial processing of terrestrial DOM and possible release of nutrients incorporated in the DOM.

Colonization by common reed (Phragmites australis) is often assumed to be driven mainly by vegetative growth of rhizomes. Seedlings are rarely observed in the field despite the annual flowering, the large seed production, and germination potential. We considered that this was mainly a consequence of the rare occurrence of the regeneration window of reed but, provided the suitable conditions were created, reed could efficiently colonize empty space by seedling establishment. We analyzed the relative importance of sexual and asexual propagation in a reed-dominated marsh in Southern France using past aerial photographs to reconstruct the reedbed dynamics over the last 25 years and a full-scale experiment simulating a rarely occurring low water level in spring. We observed phases of slow colonization corresponding to vegetative growth and periods of rapid closure of mudflats by reed. Reedbed dynamics were a combination of slow vegetative growth and a few phases of seedling establishment. The preservation of stable water levels favored colonization by vegetative growth. The experimental spring drawdown led to a 25% increase in reed area with up to 40 m progressions. Such rare events with low water levels in spring favor sexual colonization. Sexual reproduction plays an important role in the pioneer stage of reedbeds, allowing both fast progression and establishment of genetically diverse stands.

Vegetation pattern and dynamics were characterized across a mid-Texas, USA coastal marsh ecotone subjected to snow goose herbivory, drought, and salt-water pulses. For eight years following snow goose feeding, species cover was evaluated in heavy and light goose-use patches at increasing distances from tidal influence. Just prior to and for two years after the feeding event, drought, and several salt-water pulses associated with tropical storms typified the hydrologic dynamics of the marsh. Herbivory history was more important than distance from tidal influence, salinity, or flooding in explaining spatial and temporal vegetation pattern for three years. Precipitation variation influenced vegetation dynamics in areas heavily used by geese. Recovery to pre-herbivory composition and abundance required six years without further snow goose feeding. Extremes of annual precipitation, salinities, and water levels impacted cover of Spartina patens dominated patches little unless feeding snow geese uprooted vegetation. Schoenoplectus americanus was more impacted by extremes of environmental dynamics than S. patens but even more impacted by synergistic effects of uprooting and environmental extremes. During this period, the ecotone could be characterized as patchy, with a gulfward waxing and waning of S. americanus.

Human alterations of the hydrologic regime during the past century have threatened the integrity of the subtropical Everglades. The monumental government-sponsored effort that is currently underway to restore the structure and function of this ecosystem has the rebirth of reasonably natural water flows as a major focus. However, this wet season-dry season system also is hostage to natural rainfall events and frequent tropical cyclones, which periodically cause severe flooding. This study examined the effect of severe high water levels, resulting from above normal summer rainfall and a fall tropical storm in 1994–1995, on white-tailed deer (Odocoileus virginianus seminolus), an important prey base for the endangered Florida panther (Puma concolor coryi) and other endemic carnivores. Flood waters at depths exceeding 60 cm, the generally accepted depth at which deer mobility is compromised, existed from November 1994 through the early half of 1995. Of 51 radiocollared deer alive at the onset of the flood on 1 November 1994, 25 (50%) died prior to 31 March 1995. The annual death rate of adult deer during the flood year was approximately double that of pre-flood years. Fawn production in 1995 appeared to be reduced approximately 10-fold from that in 1994, the pre-flood year. High water levels restricted use by deer of wet prairie habitat (87%), characterized by higher quality forage, and forced them to the slightly elevated tree islands (7%), characterized by lower quality forage. These findings demonstrate that severe high water events are detrimental to growth and maintenance of white-tailed populations in the Everglades. As a management safeguard, it is recommended that the water-depth levels considered to influence deer populations negatively in the Everglades system be lowered to 50 cm from the previously published level of about 60 cm. Strategies to restore functional hydrologic regimes to enhance floral and faunal benefits in the Everglades also must include consideration of the effects of natural weather events.

Prescribed burning is often used in wetlands to remove plant litter, decrease woody or invasive species, and increase use by wetland birds. However, little is known about the within-season, short-term response of wetland birds to prescribed burning, especially during spring migration. We surveyed use of 19 burned and 19 unburned (reference) wetlands by migratory birds in the Rainwater Basin region of Nebraska, USA during three spring migrations, 2002–2004. We calculated the change in avian abundance and species richness, as well as generating the Sørenson's similarity index for burned and reference wetlands in the weeks immediately before and after burning. We compared Sørenson's index values and percent change in abundance and species richness between burned and reference wetlands using an analysis of covariance with week and wetland area as covariates to account for migration chronology and differences in the area of experimental units. Following removal of effects due to wetland area and week, burning had no effect on the percent change in avian abundance and species richness. Sørenson's index also did not differ between burned and reference wetlands. Prescribed burning did not improve use of wetlands by migratory birds in the short term. Understanding the immediate and long-term effects of prescribed burning on migratory avian abundance, species richness, and community composition is imperative for management decisions.

The fate of vascular plant detritus and the microbial communities and processes involved during the decomposition of litter are important aspects in elucidating energy flow and nutrient cycling in wetlands. Therefore, we collected and identified conspicuous fungal sporocarps in situ and isolated microfungi from living and dead Typha latifolia (cattail) leaf tissues. Cattail is a dominant plant species in southern boreal and temperate marshes and abundant in the Low Boreal Mixedwood ecoregion in central Alberta, Canada. Following two successive field collections in early and late summer 2001, 45 different fungal taxa were identified. There were 26 ascomycetes, five basidiomycetes, and 14 anamorphic taxa, most of them with putative ascomycetous affinities. Twenty-four taxa represented new records for T. latifolia, 12 were new to Canada, and seven were new to North America. Also, five taxa were new reports outside of the country of the type locality. To elucidate their roles in the decomposition of T. latifolia leaves, we examined 33 taxa for their ability to use cellulose, gelatin, starch, tannic acid, and lignin as carbon sources (based on calorimetric tests), as well as to cause mass losses of sterile T. latifolia leaves. The number of fungi using cellulose and gelatin as carbon sources was significantly greater than those using starch, tannic acid, or lignin. Mass losses of T. latifolia leaf tissues by ascomycetes and basidiomycetes ranged from 1.3 to 54.6% and −0.4 to 52.1%, respectively. There was a positive relationship between mass loss of T. latifolia leaves and cellulose degradation but not between mass loss and any of the other carbon sources. Our data showed that a taxonomically diverse suite of fungi effectively degrades this plant material; however, additional studies examining the decomposer communities of other dominant wetland plants are necessary to gain a better understanding of nutrient and energy dynamics in wetlands at the ecosystem level.

Pattern and zonation of peatland vegetation are regulated by environmental gradients, as well as by effects of biomass and competitive exclusion on distribution of species richness. The interplay of these factors has not been closely examined in calcareous prairie fens, which are isolated, species rich, calcareous peatlands in the Prairie Peninsula region of North America. We used multivariate analyses to classify vegetation and to quantify species richness in relation to substrate conditions and vegetation structure in a 23-ha calcareous prairie fen in northeast Illinois, USA. Plant assemblages formed a floristic continuum across sedge meadow, graminoid fen, calcareous seep, marl flat, and spring run vegetation, with complete dissimilarity between spring run and sedge meadow. These vegetation zones corresponded to gradients of decreasing organic content and cation exchange capacity, and increasing pH, Na, Mg, and total Ca concentrations, which reach extremes in spring run and marl flats. Species richness was unimodal across the fen gradient, fitting an expected model of low richness in vegetation either with large biomass (as shown by low light penetration in tall sedge meadow) or with environmentally harsh conditions and low biomass (shown by high light penetration in short marl flat and spring run vegetation). These biotic and abiotic factors, as well as hydrology, mediate vegetation pattern across the fen.

Insufficient water supply and poor water quality are major problems in the Klamath Basin of southern Oregon and northern California, USA. Various land-management practices and competing demands for water in much of the basin have led to degraded environmental conditions and poor water quality (excessive nutrients, warm temperatures, high pH, low dissolved oxygen). Of particular interest are the water-quality impacts of wetland management at Lower Klamath National Wildlife Refuge. Wetlands in the refuge are intensely managed through a system of canals, drains, and water-control structures, but the impacts of this management are not known. Data for inflows, outflows, field water-quality parameters, and nutrient concentrations were collected and analyzed in 1999 and 2000. Water budgets and nutrient loads were developed for the refuge. Water-quality impacts from wetland management include higher conductivity and water temperatures but lower turbidity. Outflow nutrient concentrations of N and P are generally increased relative to inflow concentrations, but nutrient loads are reduced. From 55 to 77% of the mass of N and 19 to 51% of the mass of P entering the refuge wetlands is retained. Seasonal wetlands retain less P than permanent wetlands or farmed units, possibly because of the annual drying cycle, the later drainage dates, and predominance of annual vegetation. For all refuge wetlands, dissolved inorganic N is retained more efficiently than particulate N, and particulate P is retained more efficiently than soluble reactive P. The ultimate effect of refuge wetland management is to decrease net N and P loads but increase the ratio of bioavailable P to bioavailable N in the refuge outflow.

Most studies on the decomposition of Phragmites australis have concentrated on permanently submerged or standing litter. The present study examines the dynamics of leaf and stem litter breakdown in seasonally flooded and permanently exposed areas in a managed reedbed. Seasonal flooding and summer drawdown are employed as part of the management to prevent litter accumulation. Fine mesh (0.25 mm) and modified design, coarse mesh (5-mm) bags were used. In the permanently exposed area, leaf and stem material lost 42% of their dry weight after 18 months and 47% after 30 months. In the seasonally flooded area, depending on mesh size, leaf material lost 74–79% and stem material 60–79% of its dry weight over the same time periods. Examination of individual breakdown rates demonstrated that fastest weight losses occurred following summer drawdown, with well-oxygenated, warm, damp litter. Drying of the litter and re-flooding of the reedbed led to slowing or complete cessation of breakdown. Maintenance of damp conditions throughout the summer exposure period would maximize breakdown rates.

I reviewed information from 73 sources on soil animals in flooded grassland, focusing on soil macrofauna: snails and slugs (Gastropoda), earthworms (Lumbricidae), potworms (Enchytraeidae), woodlice (Isopoda), millipedes (Chilopoda, Diplopoda), Diptera, and other insect larvae. While the database on earthworms was rather comprehensive, studies on all other soil fauna groups, especially regarding their role in wetlands were few and showed major research needs. The survival strategies of the groups were compared systematically. Annelids and insect larvae had the best physiological adaptations, other groups only reacted with evasion by active or passive movement and by recolonization and reproduction from resistant stages. There were no typical “wetland species” in soil macrofauna, only tolerant hygrophilous species. Flooding of grassland immediately reduced diversity, abundance, and biomass of all groups of soil macrofauna. Their community structure was altered, and well-adapted species, often wide-spread opportunists, became more abundant while others disappeared. The effects increased with the duration of flooding and rising temperature but were usually compensated for during the next soil-dry period. A meta-analysis classified sites according to duration, frequency, and seasonality of inundation. In general, species numbers and abundances of earthworms, woodlice, and millipedes tended to be lower in frequently and/or extensively flooded sites. Only gastropods are favored by moderate winter flooding. In bogs, even when they are waterlogged the entire year, species numbers are distinctly higher than the most frequently flooded sites. The impact of episodic summer flooding events is transitional and less pronounced than that of regular winter flooding. Earthworms re-establish soil structure after flooding, and they are, next to dipteran larvae, an important prey for wetland birds. Slow, moderate flooding in winter, waterlogging in spring, and a landscape mosaic with non-flooded refuge sites is recommended for water management policies favorable for both soil fauna and wetland birds.

Vegetation in intermittently flooded wetlands is strongly affected by the influence of hydrologic condition on species establishment and survival. The vegetation of four herbaceous depression meadow Carolina bay wetlands on the Upper Coastal Plain in the southeastern USA was sampled while systems were flooded in 1999 and again in 2002, near the end of a multi-year drought during which all bays were dry. The seed banks of these bays were sampled in the spring of 2000 and their relationship to the extant vegetation at both ends of the hydrologic spectrum examined. All bays lost previously abundant perennial aquatic species during the drought, and grasses, especially a rhizomatous perennial, Panicum hemitomon, expanded. While approximately half the species in the vegetation were also found in the seed bank, more than 60% of species in the seed bank were never detected in the vegetation. Also, widespread species in the vegetation, especially grasses and aquatic herbs, were rare or absent in the seed bank. The results of the study were consistent with a cyclic model of herbaceous Carolina bay vegetation dynamics in which aquatic and grass species dominate in turn as climate oscillates between wet and dry periods. Further, it appears that, in herbaceous Carolina bays, a handful of dominant aquatic and grass species in the vegetation may influence composition more strongly than widespread recruitment from the seed bank as hydrologic condition fluctuates.

In a system with mercury contamination, there are trade-offs between beneficial functions of a wetland and environmental risk of methyl mercury (MeHg) production. This project used five wetland mesocosms with three different experimental designs to assess the potential for nutrient, sediment, and total mercury (THg) removal and MeHg production associated with a proposed a large-scale wetland system. The latter was suggested for the mouth of Steamboat Creek (Nevada, USA) at the confluence with the Truckee River. Steamboat Creek has been documented to have high mercury concentrations and is a major source of nutrients to the river. Mesocosms that had creek sediments as the base and creek water as inflows resulted in decreasing THg concentration by 72–82%. Average percent nitrogen and phosphorus and suspended solids removal were 43%, 30%, and 70%, respectively. Net MeHg production was observed during spring, summer, and fall months; however, in the winter, these mesocosms acted as a sink. One wetland mesocosm with sediments low in mercury and creek water showed similar trends. Mesocosms with creek sediments and water low in mercury were a source of MeHg year round, with outflow concentrations 10 to 200 times that in the inflow. Based on the developed data, the environmental risk of the proposed large-scale wetland would be an increase of methyl mercury concentration in creek water that reaches the Truckee River by as much as 20 to 75%. However, the wetland would also be a significant sink for nutrients, suspended solids, and total mercury, decreasing the amount of mercury available for methylation downstream.

Cheyenne Bottoms, Kansas, USA has been designated by the Ramsar convention as a Wetland of International Importance. However, since that 1988 designation, cattail (Typha spp.) has become the dominant plant within the basin, and migratory bird use has decreased. We examined the effects of different cattail-management treatments (burned, disked, and grazed by 5 and 20 head of cattle) on macroinvertebrates used as food resources by migratory birds. We found few differences in diversity, biomass, or density of macroinvertebrates among treatments. When differences existed, diversity, biomass, and density were greater within the control or more heavily vegetated treatments (e.g., burned) than within less vegetated treatments (e.g., disked). Macroinvertebrate densities, particularly Chironomidae, ranged from 154 to 681/m²; however, they were up to seven times lower than historic densities and well below the 5000/m² that has been suggested for supporting large numbers (0.5 million) of migratory waterbirds. Thus, Cheyenne Bottoms' capacity to support migratory waterbirds may currently be reduced due to low macroinvertebrate densities in areas where cattail has invaded, as well as in areas where cattail has been managed. Research and management should be targeted at restoring the hydrology and dependent biotic communities that support migratory birds.

Wetlands are abundant throughout the prairie pothole region (PPR), an area comprising over 700,000 km² in central North America. Prairie wetland communities are strongly influenced by regional physiography and climate, resulting in extreme spatial and temporal variability relative to other aquatic ecosystems. Given the strong influence of abiotic factors, PPR wetland communities have been viewed traditionally in the context of their responses to chemical and physical features of landscape and climate. Although useful, this physical-chemical paradigm may fail to account for ecosystem variability due to biotic influences, particularly those associated with presence of fish. Spatial and temporal variability in fish populations, in turn, may reflect anthropogenic activities, landscape characteristics, and climate-mediated effects on water levels, surface connectivity, and hydroperiods. We reviewed studies assessing influences of fish on prairie wetlands and examined precipitation patterns and biological data from PPR wetlands in east-central North Dakota and western Minnesota, USA. Our review and analysis indicated that native fish influence many characteristics of permanently flooded prairie wetlands, including water clarity and abundance of phytoplankton, submerged macrophytes, and aquatic invertebrates. We suggest that ecologists and managers will benefit from conceptual paradigms that better meld biotic interactions associated with fish, and perhaps other organisms, with chemical and physical influences on prairie wetland communities.

About 700,000 mangroves, chiefly Avicennia marina, were grown in the tree-less mud flats of Eritrea by a newly developed technology that provides required nitrogen, phosphorus, and iron. A method of fertilization was devised that eliminates the possibility of fertilizer runoff. Novel methods have been developed for planting seeds at the final site and protecting seedlings from uprooting by wave action and encircling wrasse. Methods were developed for preserving mangrove seeds by sun-drying, which results in a stable grain-like product. However, dried mangrove seeds and foliage are insufficient for supporting good growth of sheep, which was a desired outcome. Supplementation of mangrove material with small quantities of a stress food for sheep, consisting of fat-soluble vitamins and minerals renders the mangroves an adequate food. Together, these findings are capable of forming a profitable sea water agriculture and relieving hunger and poverty in many regions of the world.

This study analyzed change of a coastal wetland using remote sensing, image processing, and GIS techniques. Aerial photographs from 1928, 1945, 1975, and 1994 were acquired for San Dieguito Lagoon, in San Diego County, California, USA. The photographs were scanned and the landscape classified as wetland or non-wetland. A GIS model quantified and indicated trends in wetland change. Results show that, in 1928, 50% (366 ha) of the study area was comprised of wetlands. By 1994, the total wetland area decreased to 15% (109 ha) of the study site area. The annualized loss reveals a continual decrease in the rate of loss over all three time periods, which corresponds to the national decline in the rate of wetland loss. The greatest loss rate occurred from 1928 to 1945 (3% per year), and the lowest rate of loss occurred from 1975 to 1994 (0.3% per year).